Todd and Atamas: Survival in pulmonary fibrosis combined with emphysema: likely defined by charac... more Todd and Atamas: Survival in pulmonary fibrosis combined with emphysema: likely defined by characteristics of specific patient subpopulations. Fibrogenesis & Tissue Repair 2011 4:17.
Interleukin-4 (IL-4) acts on cultured cells in a species-specific fashion, although several repor... more Interleukin-4 (IL-4) acts on cultured cells in a species-specific fashion, although several reports have suggested that human (h) IL-4 may be functionally active in rodents in vivo. The latter finding, if true, would not only offer possibilities for pre-clinical testing of novel hIL-4-targeting therapies in animals, but also suggests new opportunities for mechanistic studies of IL-4 and its receptors. Conventional IL-4 is encoded by four exons, whereas its poorly studied alternatively spliced isoform is encoded by exons 1, 3 and 4 (IL-4d2). Replication-deficient adenovirus-mediated gene delivery of hIL-4 isoforms (hIL-4 or hIL-4d2) to mouse lungs caused similar pulmonary infiltration of T and B lymphocytes, but not eosinophils. There were significant differences in the changes of pulmonary cytokine milieu induced by hIL-4 compared with hIL-4d2, with hIL-4d2 inducing higher levels of pro-inflammatory (tumour necrosis factor-a, IL-1, and monocyte chemotactic protein-1) and T helper type 1 (IL-12 and interferon-c) cytokines. There was no elevation in endogenous mouse (m) IL-4 or mIL-4d2 mRNAs, and germ-line deficiency of mIL-4 did not affect the degree of pulmonary infiltration. When combined with an ovalbumin model of asthma, hIL-4d2 stimulated a greater accumulation of lymphocytes than did hIL-4. Pulmonary infiltration of lymphocytes induced by expression of hIL-4 or hIL-4d2 was attenuated, but not completely abrogated, by germ-line deficiency of mIL-4Ra or murine signal transducer and activator of transcription 6, suggesting that these signalling molecules mediate the in vivo effects of hIL-4 isoforms in mice. These findings suggest that splice isoforms of human IL-4 are functionally active in vivo in mice, and partially share the effects of the corresponding species-specific isoforms.
To gain insight into sialic acid biology and sialidase/neuraminidase (NEU) expression in mature h... more To gain insight into sialic acid biology and sialidase/neuraminidase (NEU) expression in mature human neutrophil (PMN)s, we studied NEU activity and expression in PMNs and the HL60 promyelocytic leukemic cell line, and changes that might occur in PMNs undergoing apoptosis and HL60 cells during their differentiation into PMN-like cells. Mature human PMNs contained NEU activity and expressed NEU2, but not NEU1, the NEU1 chaperone, protective protein/cathepsin A(PPCA), NEU3, and NEU4 proteins. In proapoptotic PMNs, NEU2 protein expression increased > 30.0-fold. Granulocyte colonystimulating factor protected against NEU2 protein upregulation, PMN surface desialylation and apoptosis. In response to 3 distinct differentiating agents, dimethylformamide, dimethylsulfoxide, and retinoic acid, total NEU activity in differentiated HL60 (dHL60) cells was dramatically reduced compared to that of nondifferentiated cells. With differentiation, NEU1 protein levels decreased > 85%, PPCA and NEU2 proteins increased > 12.0-fold, and 3.0-fold, respectively, NEU3 remained unchanged, and NEU4 increased 1.7-fold by day 3, and then returned to baseline. In dHL60 cells, lectin blotting revealed decreased α2,3-linked and increased α2,6-linked sialylation. dHL60 cells displayed increased adhesion to and migration across human bone marrow-derived endothelium and increased bacterial phagocytosis. Therefore, myeloid apoptosis and differentiation provoke changes in NEU catalytic activity and protein expression, surface sialylation, and functional responsiveness. Polymorphonuclear leukocyte (PMN)s are part of the first line of host defenses against invasive prokaryotic pathogens 4 . Myeloid progenitors undergo maturation within the bone marrow into mature PMNs 1,2 . These motile and highly deformable cells are capable of percolating through and exiting the bone marrow sinusoids, circulating through the intravascular compartment, and recognizing and engaging adhesion molecules surface-expressed on the endothelium. PMNs undergo profound shape changes permitting these cells to squeeze through the small caliber microvasculature and interendothelial cell junctions to enter extravascular tissues 3 , where they adhere to and engulf bacteria for successful phagocytosis and intracellular killing 4 . The HL60 promyelocytic leukemia cell line has been used as a model for myelopoiesis, and its differentiation towards PMN-like cells has been used as a surrogate for short-lived, difficult to manipulate PMNs 5-8 . For example, these same HL60 cells are regularly used in opsonophagocytic assays to establish opsonic activity of vaccine-induced antibodies 9 . Given the critical role of sialic acid (SA), neuraminidase/sialidase (NEU), and sialyltransferase (ST) expression in PMN function 10-13 , we examined their impact on HL60 cellular responsiveness. SAs comprise a family of 9-carbon sugars, each carboxylated on the C1 position . These SA residues are almost always located at the terminus of glycan chains, where they are strategically positioned to influence intermolecular and cell-cell interactions. SA on the cell surface imparts a negative surface charge that generates
Trait diversity -the substrate for natural selection -is necessary for adaptation through selecti... more Trait diversity -the substrate for natural selection -is necessary for adaptation through selection, particularly in populations faced with environmental changes that diminish population fitness. In habitats that remain unchanged for many generations, stabilizing selection maximizes exploitation of resources by reducing trait diversity to a narrow optimal range. One might expect that such ostensibly homogeneous populations would have a reduced potential for heritable adaptive responses when faced with fitness-reducing environmental changes. However, field studies have documented populations that, even after long periods of evolutionary stasis, can still rapidly evolve in response to changed environmental conditions. We argue that degeneracy, the ability of diverse population elements to function similarly, can satisfy both the current need to maximize fitness and the future need for diversity. Degenerate ensembles appear functionally redundant in certain environmental contexts and functionally diverse in others. We propose that genetic variation not contributing to the observed range of phenotypes in a current population, also known as cryptic genetic variation (CGV), is a specific case of degeneracy. We argue that CGV, which gradually accumulates in static populations in stable environments, reveals hidden trait differences when environments change. By allowing CGV accumulation, static populations prepare themselves for future rapid adaptations to environmental novelty. A greater appreciation of degeneracy's role in resolving the inherent tension between current stabilizing selection and future directional selection has implications in conservation biology and may be applied in social and technological systems to maximize current performance while strengthening the potential for future changes.
American Journal of Respiratory Cell and Molecular Biology, Sep 1, 2006
Human CC chemokine ligand (CCL)-18, also called pulmonary and activation-regulated chemokine (PAR... more Human CC chemokine ligand (CCL)-18, also called pulmonary and activation-regulated chemokine (PARC), macrophage inflammatory protein (MIP)-4, alternative macrophage activationassociated CC chemokine (AMAC)-1, dendritic cell chemokine (DC-CK1), and small secreted cytokine A (SCYA)-18, is produced at high levels in the lungs (1), particularly by alveolar macrophages that normally acquire alternatively activated phenotype (2). This chemokine is also produced, although to a lesser degree, by peripheral blood monocytes, tissue macrophages, and dendritic cells (3, 4). CCL18 attracts both naı ¨ve and activated CD4ϩ and CD8ϩ T cells, but not granulocytes or monocytes (1, 3). Increased levels of CCL18 mRNA and/or protein have been reported in the lungs of patients with pulmonary fibrosis, such as in scleroderma lung disease (5), hypersensitivity pneumonitis and idiopathic pulmonary fibrosis (6), pulmonary sarcoidosis (7), and in a primate model of allergic asthma (8). We recently
Cryptic Genetic Variation (CGV) and degeneracy paradigms for adaptation are integrated in this re... more Cryptic Genetic Variation (CGV) and degeneracy paradigms for adaptation are integrated in this review, revealing a common set of principles that support adaptation at multiple levels of biological organization. Using simulation studies, molecular-based experimental systems, and principles from population genetics, we demonstrate that CGV and degeneracy reflect complementary top-down and bottom-up, respectively, conceptualizations of the same phenomenon and capture a universal feature of biological adaptive processes. Degeneracy's role in resolving conflicts between stabilizing selection and directional selection has numerous applications. For instance, we consider improved measures of intraspecific biodiversity for conservation planning, adaptive therapeutic strategies for defeating evolvable pathogens and aggressive cancers, and the translation of degeneracy as a design principle for improving flexibility in a number of abiotic technologies.
Background: Pseudomonas aeruginosa flagellin binds to the membrane-tethered mucin, MUC1. Results:... more Background: Pseudomonas aeruginosa flagellin binds to the membrane-tethered mucin, MUC1. Results: Flagellin drives NEU1 to desialylate MUC1, thereby increasing its adhesiveness for Pseudomonas aeruginosa and its shedding. Conclusion: P. aeruginosa hijacks host NEU1 through its flagellin. Significance: P. aeruginosa mobilizes NEU1 to enhance its pathogenicity, but the host retaliates by releasing MUC1 as a hyperadhesive decoy receptor. Airway epithelia express sialylated receptors that recognize exogenous danger signals. Regulation of receptor responsiveness to these signals remains incompletely defined. Here, we explore the mechanisms through which the human sialidase, neuraminidase-1 (NEU1), promotes the interaction between the sialoprotein, mucin 1 (MUC1), and the opportunistic pathogen, Pseudomonas aeruginosa. P. aeruginosa flagellin engaged the MUC1 ectodomain (ED), increasing NEU1 association with MUC1. The flagellin stimulus increased the association of MUC1-ED with both NEU1 and its chaperone/transport protein, protective protein/cathepsin A. Scatchard analysis demonstrated NEU1-dependent increased binding affinity of flagellin to MUC1-expressing epithelia. NEU1-driven MUC1-ED desialylation rapidly increased P. aeruginosa adhesion to and invasion of the airway epithelium. MUC1-ED desialylation also increased its shedding, and the shed MUC1-ED competitively blocked P. aeruginosa adhesion to cell-associated MUC1-ED. Levels of desialylated MUC1-ED were elevated in the bronchoalveolar lavage fluid of mechanically ventilated patients with P. aeruginosa airway colonization. Preincubation of P. aeruginosa with these same ex vivo fluids competitively inhibited bacterial adhesion to airway epithelia, and MUC1-ED immunodepletion completely abrogated their inhibitory activity. These data indicate that a prokaryote, P. aeruginosa, in a ligand-specific manner, mobilizes eukaryotic NEU1 to enhance bacterial pathogenicity, but the host retaliates by releasing MUC1-ED into the airway lumen as a hyperadhesive decoy receptor.
Chronic inflammation and fibrosis are hallmarks of lung pathology of newborn Ureaplasma infection... more Chronic inflammation and fibrosis are hallmarks of lung pathology of newborn Ureaplasma infection. We hypothesized that antenatally acquired Ureaplasma stimulates a chronic inflammatory, profibrotic immune response that contributes to lung injury, altered developmental signaling, and fibrosis. Lung specimens from 125-d gestation baboon newborns ventilated for 14 d that were either infected antenatally with Ureaplasma serovar 1 or noninfected, and 125-d and 140-d gestational controls were obtained from the Baboon BPD Resource Center (San Antonio, TX). Trichrome stain to assess fibrosis and immunohistochemistry for ␣-smooth muscle actin (␣-SMA) and transforming growth factor  1 (TGF 1 ) were performed. Lung homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA) for cytokines [tumor necrosis factor ␣ (TNF␣), interleukin (IL)-1, TGF 1 , oncostatin M (OSM), IL-10, and interferon ␥ (IFN␥)] and the chemokine MCP-1 and by Western blot for Smad2, Smad3, and Smad7. Compared with noninfected ventilated and gestational controls, Ureaplasma-infected lungs demonstrated more extensive fibrosis, increased ␣-SMA and TGF 1 immunostain- ing, and higher concentrations of active TGF 1 , IL-1, and OSM, but no difference in IL-10 levels. There was a trend toward higher Smad2/Smad7 and Smad3/Smad7 ratios in Ureaplasma lung homogenates, consistent with up-regulation of TGF 1 signaling. Collectively, these data suggest that a prolonged proinflammatory response initiated by intrauterine Ureaplasma infection contributes to early fibrosis and altered developmental signaling in the immature lung.
Purpose of Review-Premature activation of aging-associated molecular mechanisms is emerging as an... more Purpose of Review-Premature activation of aging-associated molecular mechanisms is emerging as an important contributor to many diseases, including scleroderma. Among central regulators of the aging process are a group of histone deacetylases called sirtuins (SIRTs). Recent findings implicate these molecules as pathophysiological players in scleroderma skin and lung fibrosis. The goal of this article is to review recent studies on the involvement of SIRTs in scleroderma from the perspective of aging-related molecular mechanisms. Recent Findings-Despite a degree of controversy in this rapidly developing field, the majority of data suggest that SIRT levels are decreased in tissues from patients with scleroderma compared to healthy controls as well as in animal models of scleroderma. Molecular studies reveal several mechanisms through which declining SIRT levels contribute to fibrosis, with the most attention given to modulation of the TGF-β signaling pathway. Activation of SIRTs in cell culture and in animal models elicits antifibrotic effects. Summary-Declining SIRT levels and activity are emerging as pathophysiological contributors to scleroderma. Restoration of SIRTs may be therapeutic in patients with scleroderma.
American Journal of Respiratory Cell and Molecular Biology, Dec 1, 2013
The mechanisms of interstitial lung disease (ILD) remain incompletely understood, although recent... more The mechanisms of interstitial lung disease (ILD) remain incompletely understood, although recent observations have suggested an important contribution by IL-33. Substantial elevations in IL-33 expression were found in the lungs of patients with idiopathic pulmonary fibrosis and scleroderma lung disease, as well as in the bleomycin injury mouse model. Most of the observed IL-33 expression was intracellular and intranuclear, suggesting involvement of the full-length (fl) protein, but not of the proteolytically processed mature IL-33 cytokine. The effects of flIL-33 on mouse lungs were assessed independently and in combination with bleomycin injury, using recombinant adenovirusmediated gene delivery. Bleomycin-induced changes were not affected by gene deficiency of the IL-33 receptor T1/ST2. Combined flIL-33 expression and bleomycin injury exerted a synergistic effect on pulmonary lymphocyte and collagen accumulation, which could be explained by synergistic regulation of the cytokines transforming growth factor-b, IL-6, monocyte chemotactic protein-1, macrophage inflammatory protein-1a, and tumor necrosis factor-a. By contrast, no increase in the levels of the Th2 cytokines IL-4, IL-5, or IL-13 was evident. Moreover, flIL-33 was found to increase the expression of several heat shock proteins (HSPs) significantly, and in particular HSP70, which is known to be associated with ILD. Thus, flIL-33 is a synergistic proinflammatory and profibrotic regulator that acts by stimulating the expression of several non-Th2 cytokines, and activates the expression of HSP70.
tions after transplantation, we analyzed the T-cell repertoire expressed in bronchoalveolar lavag... more tions after transplantation, we analyzed the T-cell repertoire expressed in bronchoalveolar lavage fluids from eleven patients with graft-versus-host disease following BMT. A reverse transcriptase-polymerase chain reaction was used to amplify rearranged TCR transcripts in unfractionated, CD4+, and CD8+ T cells from bronchoalveolar lavage fluids. The relative expression of TCR variable (V) gene families and the diversity of junctional region lengths associated with different AV and BV gene families were analyzed. Nearly all TCR AV and BV gene families were detected in bronchoalveolar lavage cells from BMT recipients. Oligoclonal patterns of TCR junctional region lengths were observed in unfractionated, CD4+, and CD8+ bronchoalveolar T cells. The oligoclonal expansion of bronchoalveolar T cells in patients was confirmed by DNA sequencing. TCRV gene expression is almost completely restored in the lungs of BMT recipients as early as two weeks after transplantation. Increased oligoclonality among TCR gene families suggests either an incomplete restoration of TCR diversity or an antigen-driven expansion of T cells in the lungs of BMT recipients with graft-versus-host disease, not necessarily related to pulmonary infection. Am.
Interleukin (IL)-33 and its receptor ST2 have been recently implicated as critical regulators of ... more Interleukin (IL)-33 and its receptor ST2 have been recently implicated as critical regulators of responses to injury and of ensuing inflammation. The roles of IL-33 and ST2 in pulmonary inflammation and scarring remain unclear. We analyzed bronchoalveolar lavage (BAL) from patients with idiopathic pulmonary fibrosis (IPF), a disease characterized by inflammation, with known elevated levels of IL-8 and excessive collagen deposition in the lungs. IL-33 was not found in BAL from 5 controls but was found in 7 out of 11 IPF samples, at 10.0 ± 3.2 pg/ml. Soluble ST2 was found in BAL from healthy controls at 93.2 ± 82.1 pg/ml, and in all IPF samples at 352.1 ± 135.2 pg/ml (p < 0.05, Mann-Whitney U test). The elevation of IL-33 in BAL suggested that this cytokine may act directly on pulmonary epithelial cells and through this action contribute to inflammation. Cultured human primary pulmonary epithelial cells were stimulated with rhIL-33, and the levels of pro-inflammatory cytokines IL-6, IL-8, MIP-1α, and TNF-α in cell culture media were analyzed by ELISA. Of the analyzed cytokines, only the levels of IL-8 were increased by 2.0 ± 0.2 fold at 24 h and 1.7 ± 0.2 fold at 48 h. In conclusion, levels of IL-33 and ST2 are elevated in the lungs of IPF patients; IL-33 may contribute to inflammation and fibrosis by activating IL-8 production in pulmonary epithelium.
Previous reports have been inconsistent on whether Interleukin (IL)-33 necessarily promotes Th2 e... more Previous reports have been inconsistent on whether Interleukin (IL)-33 necessarily promotes Th2 effects in vivo. This diversity of findings may be due to post-synthetic processing of IL-33. We compared the in vivo effects of full-length mouse (flm) and mature mouse (mm) IL-33 utilizing replication-deficient adenovirus (AdV)-mediated gene delivery. mmIL-33 promoted pulmonary eosinophilia, neutrophilia, and significant elevations in IL-4, IL-5, and IL-13 compared to AdV-NULL-infected controls (p < 0.05 in all cases), whereas flmIL-33 had no such effects. A possibility was considered that flmIL-33 may modulate the effects of a prototypic Th2 cytokine, IL-4. The effects of AdV-mediated gene delivery of IL-4 were compared with the effects of combined flmIL-33 and mIL-4. In the latter case, a bicistronic AdV construct encoding flmIL-33 and mIL-4 was used to ensure co-localization of expression of both cytokines. On day 7 after instillation of the viral particles, IL-4-expressing mice had elevated eosinophils and neutrophils in their BAL, and animals expressing both flmIL-33 and IL-4 had yet significantly more BAL eosinophils and neutrophils compared with IL-4-expressing mice (p < 0.05). Similar potentiating effects of flmIL-33 were observed on IL-4-driven increases in pulmonary cytokines TNF-α, IL-5, IL-13, MCP-1, and in goblet cell hyperplasia. These results suggest that although full-length IL-33 has no independent pro-Th2 effect on the lung, it potentiates such effects of IL-4.
Interstitial lung disease, a combination of pulmonary inflammation and fibrosis, is deadly and oc... more Interstitial lung disease, a combination of pulmonary inflammation and fibrosis, is deadly and occurs idiopathically or as a complication of autoimmune rheumatic diseases (scleroderma, rheumatoid arthritis, poly- and dermatomyositis, lupus). T cells often accumulate in the lungs of such patients. Previous reports suggested that αV-containing integrins may activate TGF-β and facilitate fibrosis. Whether pulmonary T cells utilize such integrins in interstitial lung disease is not clear. Expression of integrins αVβ3 (ITGAVB3) or αVβ5 (ITGAVB5) on pulmonary T cells was observed by double-stain immunofluorescence confocal microscopy in six out of six patients with scleroderma lung disease, as well as in the animal models of pulmonary CCL18 overexpression that manifests in selective T lymphocytic infiltration of the lungs and T cell-dependent pulmonary fibrosis. Flow cytometry of bronchoalveolar lavage T cells confirmed expression of integrins on more than 10% (up to 50%) of pulmonary T cells in 14 of 25 scleroderma patients and in all CCL18-overexpressing mice; Q-PCR experiments confirmed elevated integrin mRNAs in purified BAL T cells. There was no expression of ITGAVB3 or ITGAVB5 on T cells from the lungs of healthy volunteers or control mice. Injections of anti-ITGB3 blocking antibody or genetic deficiency of ITGB3 protected mice from CC18-induced inflammation and fibrosis. Jurkat cells that were forced to overexpress ITGAVB3 or ITGAVB5 induced Smad2 phosphorylation and nuclear translocation, and increases in collagen and α-smooth muscle actin expression in co-cultures with primary lung fibroblasts. Blocking anti-TGF-β antibodies attenuated such regulation in cell co-cultures. Thus, expression of integrins on pulmonary T cells contributes to interstitial lung disease by promoting T cell infiltration, TGF-β activation, and fibrosis.
We have previously shown that IL-4δ2, a naturally occurring in humans and other species splice va... more We have previously shown that IL-4δ2, a naturally occurring in humans and other species splice variant of IL-4, competes with IL-4 for receptor binding and inhibits some of IL-4 effects on lymphocytes and monocytes. Numerous groups reported that the levels and the ratio of IL-4δ2 and IL-4 mRNAs change in immune, inflammatory, and infectious diseases. It has been suggested that recombinant human (rh) IL-4δ2 can be used therapeutically to neutralize the harmful effects of excess IL-4 in vivo, although it was not clear whether IL-4δ2 mRNA expressing cells secrete IL-4δ2 protein. Transfection of HEK293 or Jurkat cells with IL-4δ2-encoding constructs resulted in IL-4δ2 protein secretion confirmed by LC/MS, ELISA, and Western blotting. To investigate whether IL-4δ2 has no independent activity and acts only as an inhibitor of IL-4, we overexpressed human IL-4δ2 in mouse lungs. Adenovirus-mediated gene delivery of IL-4δ2 caused lymphocytic infiltration similar to that in IL-4-overexpressing mice, as well as proinflammatory/Th1 changes in pulmonary milieu, with the induced levels of TNF-α, IL-1, IFN-γ, IL-12p40, and MCP-1 significantly exceeding those induced by gene delivery of IL-4. Germline deficiency of STAT6 had no effect, whereas deficiency of IL-4Rα significantly attenuated IL-4δ2-induced or IL-4-induced changes in the lungs. Stimulation of primary human T cells or PBMC, but not fibroblasts or A549 cells, with rhIL-4δ2 induced phosphorylation of Jak1, Jak3, and Tyk2, but not of STAT6. IL-4δ2 potently induced production of MCP-1 in human T cells and upregulated IL-4δ2 mRNA production in an autocrine fashion by several hundred fold. Thus, IL-4δ2 is secreted as a protein, acts as a potent autocrine regulator of inflammation and immunity in an IL-4Rα-dependent STAT6-independent fashion, and is a potential novel target for future therapies.
Activities of T lymphocytes are centrally regulated by interactions between multiple members of t... more Activities of T lymphocytes are centrally regulated by interactions between multiple members of the TNF/TNF-R family. TRAIL is a member of the TNF family with pro-apoptotic activity. The only signaling TRAIL receptor in mice is death receptor (DR) 5. CCL18, a chemokine with selective chemotactic activity on T lymphocytes, is known for its involvement in pulmonary inflammation and fibrosis associated with autoimmune diseases. We measured soluble TRAIL in bronchoalveolar lavage (BAL) fluids. The levels of TRAIL were significantly elevated (p < 0.01, ANOVA) in BAL from 16 patients with scleroderma lung disease (211±110 pg/ml) compared to 16 patients without lung involvement (115±58 pg/ml), or 8 healthy controls (73±41 pg/ml). To determine whether TRAIL is important for CCL18-induced pulmonary infiltration of lymphocytes, recombinant adenovirus-mediated gene delivery of CCL18 was performed in TRAIL KO, DR5 KO, and WT mice. Overexpression of CCL18 caused profound pulmonary lymphocytic infiltration in WT and TRAIL KO mice, compared to control mice infected with AdV-NULL. In contrast, infiltration of T lymphocytes was completely abrogated in CCL18-expressing DR5 KO mice, based on lung histology. Thus, the levels of TRAIL are elevated in the lungs of patients with autoimmunity-associated inflammation and fibrosis, yet TRAIL does not appear to be involved in the CCL18-mediated T lymphocytic infiltration, whereas its receptor DR5 is required for such T cell response to CCL18.
Theoretical Biology and Medical Modelling, Dec 1, 2012
The theory of speciation is dominated by adaptationist thinking, with less attention to mechanism... more The theory of speciation is dominated by adaptationist thinking, with less attention to mechanisms that do not affect species adaptation. Degeneracythe imperfect specificity of interactions between diverse elements of biological systems and their environmentsis key to the adaptability of populations. A mathematical model was explored in which population and resource were distributed one-dimensionally according to trait value. Resource consumption was degenerateneither strictly location-specific nor location-independent. As a result, the competition for resources among the elements of the population was non-local. Two modeling approaches, a modified differential-integral Verhulstian equation and a cellular automata model, showed similar results: narrower degeneracy led to divergent dynamics with suppression of intermediate forms, whereas broader degeneracy led to suppression of diversifying forms, resulting in population stasis with increasing phenotypic homogeneity. Such behaviors did not increase overall adaptation because they continued after the model populations achieved maximal resource consumption rates, suggesting that degeneracy-driven distributed competition for resources rather than selective pressure toward more efficient resource exploitation was the driving force. The solutions were stable in the presence of limited environmental stochastic variability or heritable phenotypic variability. A conclusion was made that both dynamic diversification and static homogeneity of populations may be outcomes of the same processdistributed competition for resource not affecting the overall adaptationwith the difference between them defined by the spread of trait degeneracy in a given environment. Thus, biological degeneracy is a driving force of both speciation and stasis in biology, which, by themselves, are not necessarily adaptive in nature.
IL-4␦2 is a natural splice variant of IL-4 that lacks the region encoded by the second exon. Nume... more IL-4␦2 is a natural splice variant of IL-4 that lacks the region encoded by the second exon. Numerous reports have suggested that the expression levels of IL-4␦2 change in various diseases, especially those with pulmonary involvement, but the in vivo effects of this splice variant have never been studied. Replication-deficient, AdV-mediated gene delivery of mIL-4␦2 to mouse lungs in vivo was used, and the effects compared with similar adenoviral delivery of mIL-4 or with infection with a noncoding NULL viral construct. Overexpression of IL-4␦2 or IL-4 caused pulmonary infiltration by T and B lymphocytes, whereas in contrast to IL-4, IL-4␦2 did not induce eosinophilia or goblet cell hyperplasia. Microarray analysis of global gene expression revealed that IL-4␦2 and IL-4 had differential effects on gene expression. These splice variants also differentially regulated pulmonary levels of the cytokines TNF-␣, eotaxin, IL-1␣, IFN-␥, and MCP-1, whereas both tended to increase total lung collagen modestly. Pulmonary infiltration by lymphocytes in response to overexpression of IL-4␦2 was attenuated but not abrogated completely by germline deficiency of IL-4R␣ or STAT6, whereas deficiency of endogenous IL-4 had no effect. Thus, IL-4␦2 promotes lymphocytic inflammation in vivo (although differentially from IL-4, in part), and the effects of IL-4␦2 are not mediated by endogenous IL-4. Differential targeting of IL-4␦2 and IL-4 may therefore be considered in developing future therapeutic agents.
Todd and Atamas: Survival in pulmonary fibrosis combined with emphysema: likely defined by charac... more Todd and Atamas: Survival in pulmonary fibrosis combined with emphysema: likely defined by characteristics of specific patient subpopulations. Fibrogenesis & Tissue Repair 2011 4:17.
Interleukin-4 (IL-4) acts on cultured cells in a species-specific fashion, although several repor... more Interleukin-4 (IL-4) acts on cultured cells in a species-specific fashion, although several reports have suggested that human (h) IL-4 may be functionally active in rodents in vivo. The latter finding, if true, would not only offer possibilities for pre-clinical testing of novel hIL-4-targeting therapies in animals, but also suggests new opportunities for mechanistic studies of IL-4 and its receptors. Conventional IL-4 is encoded by four exons, whereas its poorly studied alternatively spliced isoform is encoded by exons 1, 3 and 4 (IL-4d2). Replication-deficient adenovirus-mediated gene delivery of hIL-4 isoforms (hIL-4 or hIL-4d2) to mouse lungs caused similar pulmonary infiltration of T and B lymphocytes, but not eosinophils. There were significant differences in the changes of pulmonary cytokine milieu induced by hIL-4 compared with hIL-4d2, with hIL-4d2 inducing higher levels of pro-inflammatory (tumour necrosis factor-a, IL-1, and monocyte chemotactic protein-1) and T helper type 1 (IL-12 and interferon-c) cytokines. There was no elevation in endogenous mouse (m) IL-4 or mIL-4d2 mRNAs, and germ-line deficiency of mIL-4 did not affect the degree of pulmonary infiltration. When combined with an ovalbumin model of asthma, hIL-4d2 stimulated a greater accumulation of lymphocytes than did hIL-4. Pulmonary infiltration of lymphocytes induced by expression of hIL-4 or hIL-4d2 was attenuated, but not completely abrogated, by germ-line deficiency of mIL-4Ra or murine signal transducer and activator of transcription 6, suggesting that these signalling molecules mediate the in vivo effects of hIL-4 isoforms in mice. These findings suggest that splice isoforms of human IL-4 are functionally active in vivo in mice, and partially share the effects of the corresponding species-specific isoforms.
To gain insight into sialic acid biology and sialidase/neuraminidase (NEU) expression in mature h... more To gain insight into sialic acid biology and sialidase/neuraminidase (NEU) expression in mature human neutrophil (PMN)s, we studied NEU activity and expression in PMNs and the HL60 promyelocytic leukemic cell line, and changes that might occur in PMNs undergoing apoptosis and HL60 cells during their differentiation into PMN-like cells. Mature human PMNs contained NEU activity and expressed NEU2, but not NEU1, the NEU1 chaperone, protective protein/cathepsin A(PPCA), NEU3, and NEU4 proteins. In proapoptotic PMNs, NEU2 protein expression increased > 30.0-fold. Granulocyte colonystimulating factor protected against NEU2 protein upregulation, PMN surface desialylation and apoptosis. In response to 3 distinct differentiating agents, dimethylformamide, dimethylsulfoxide, and retinoic acid, total NEU activity in differentiated HL60 (dHL60) cells was dramatically reduced compared to that of nondifferentiated cells. With differentiation, NEU1 protein levels decreased > 85%, PPCA and NEU2 proteins increased > 12.0-fold, and 3.0-fold, respectively, NEU3 remained unchanged, and NEU4 increased 1.7-fold by day 3, and then returned to baseline. In dHL60 cells, lectin blotting revealed decreased α2,3-linked and increased α2,6-linked sialylation. dHL60 cells displayed increased adhesion to and migration across human bone marrow-derived endothelium and increased bacterial phagocytosis. Therefore, myeloid apoptosis and differentiation provoke changes in NEU catalytic activity and protein expression, surface sialylation, and functional responsiveness. Polymorphonuclear leukocyte (PMN)s are part of the first line of host defenses against invasive prokaryotic pathogens 4 . Myeloid progenitors undergo maturation within the bone marrow into mature PMNs 1,2 . These motile and highly deformable cells are capable of percolating through and exiting the bone marrow sinusoids, circulating through the intravascular compartment, and recognizing and engaging adhesion molecules surface-expressed on the endothelium. PMNs undergo profound shape changes permitting these cells to squeeze through the small caliber microvasculature and interendothelial cell junctions to enter extravascular tissues 3 , where they adhere to and engulf bacteria for successful phagocytosis and intracellular killing 4 . The HL60 promyelocytic leukemia cell line has been used as a model for myelopoiesis, and its differentiation towards PMN-like cells has been used as a surrogate for short-lived, difficult to manipulate PMNs 5-8 . For example, these same HL60 cells are regularly used in opsonophagocytic assays to establish opsonic activity of vaccine-induced antibodies 9 . Given the critical role of sialic acid (SA), neuraminidase/sialidase (NEU), and sialyltransferase (ST) expression in PMN function 10-13 , we examined their impact on HL60 cellular responsiveness. SAs comprise a family of 9-carbon sugars, each carboxylated on the C1 position . These SA residues are almost always located at the terminus of glycan chains, where they are strategically positioned to influence intermolecular and cell-cell interactions. SA on the cell surface imparts a negative surface charge that generates
Trait diversity -the substrate for natural selection -is necessary for adaptation through selecti... more Trait diversity -the substrate for natural selection -is necessary for adaptation through selection, particularly in populations faced with environmental changes that diminish population fitness. In habitats that remain unchanged for many generations, stabilizing selection maximizes exploitation of resources by reducing trait diversity to a narrow optimal range. One might expect that such ostensibly homogeneous populations would have a reduced potential for heritable adaptive responses when faced with fitness-reducing environmental changes. However, field studies have documented populations that, even after long periods of evolutionary stasis, can still rapidly evolve in response to changed environmental conditions. We argue that degeneracy, the ability of diverse population elements to function similarly, can satisfy both the current need to maximize fitness and the future need for diversity. Degenerate ensembles appear functionally redundant in certain environmental contexts and functionally diverse in others. We propose that genetic variation not contributing to the observed range of phenotypes in a current population, also known as cryptic genetic variation (CGV), is a specific case of degeneracy. We argue that CGV, which gradually accumulates in static populations in stable environments, reveals hidden trait differences when environments change. By allowing CGV accumulation, static populations prepare themselves for future rapid adaptations to environmental novelty. A greater appreciation of degeneracy's role in resolving the inherent tension between current stabilizing selection and future directional selection has implications in conservation biology and may be applied in social and technological systems to maximize current performance while strengthening the potential for future changes.
American Journal of Respiratory Cell and Molecular Biology, Sep 1, 2006
Human CC chemokine ligand (CCL)-18, also called pulmonary and activation-regulated chemokine (PAR... more Human CC chemokine ligand (CCL)-18, also called pulmonary and activation-regulated chemokine (PARC), macrophage inflammatory protein (MIP)-4, alternative macrophage activationassociated CC chemokine (AMAC)-1, dendritic cell chemokine (DC-CK1), and small secreted cytokine A (SCYA)-18, is produced at high levels in the lungs (1), particularly by alveolar macrophages that normally acquire alternatively activated phenotype (2). This chemokine is also produced, although to a lesser degree, by peripheral blood monocytes, tissue macrophages, and dendritic cells (3, 4). CCL18 attracts both naı ¨ve and activated CD4ϩ and CD8ϩ T cells, but not granulocytes or monocytes (1, 3). Increased levels of CCL18 mRNA and/or protein have been reported in the lungs of patients with pulmonary fibrosis, such as in scleroderma lung disease (5), hypersensitivity pneumonitis and idiopathic pulmonary fibrosis (6), pulmonary sarcoidosis (7), and in a primate model of allergic asthma (8). We recently
Cryptic Genetic Variation (CGV) and degeneracy paradigms for adaptation are integrated in this re... more Cryptic Genetic Variation (CGV) and degeneracy paradigms for adaptation are integrated in this review, revealing a common set of principles that support adaptation at multiple levels of biological organization. Using simulation studies, molecular-based experimental systems, and principles from population genetics, we demonstrate that CGV and degeneracy reflect complementary top-down and bottom-up, respectively, conceptualizations of the same phenomenon and capture a universal feature of biological adaptive processes. Degeneracy's role in resolving conflicts between stabilizing selection and directional selection has numerous applications. For instance, we consider improved measures of intraspecific biodiversity for conservation planning, adaptive therapeutic strategies for defeating evolvable pathogens and aggressive cancers, and the translation of degeneracy as a design principle for improving flexibility in a number of abiotic technologies.
Background: Pseudomonas aeruginosa flagellin binds to the membrane-tethered mucin, MUC1. Results:... more Background: Pseudomonas aeruginosa flagellin binds to the membrane-tethered mucin, MUC1. Results: Flagellin drives NEU1 to desialylate MUC1, thereby increasing its adhesiveness for Pseudomonas aeruginosa and its shedding. Conclusion: P. aeruginosa hijacks host NEU1 through its flagellin. Significance: P. aeruginosa mobilizes NEU1 to enhance its pathogenicity, but the host retaliates by releasing MUC1 as a hyperadhesive decoy receptor. Airway epithelia express sialylated receptors that recognize exogenous danger signals. Regulation of receptor responsiveness to these signals remains incompletely defined. Here, we explore the mechanisms through which the human sialidase, neuraminidase-1 (NEU1), promotes the interaction between the sialoprotein, mucin 1 (MUC1), and the opportunistic pathogen, Pseudomonas aeruginosa. P. aeruginosa flagellin engaged the MUC1 ectodomain (ED), increasing NEU1 association with MUC1. The flagellin stimulus increased the association of MUC1-ED with both NEU1 and its chaperone/transport protein, protective protein/cathepsin A. Scatchard analysis demonstrated NEU1-dependent increased binding affinity of flagellin to MUC1-expressing epithelia. NEU1-driven MUC1-ED desialylation rapidly increased P. aeruginosa adhesion to and invasion of the airway epithelium. MUC1-ED desialylation also increased its shedding, and the shed MUC1-ED competitively blocked P. aeruginosa adhesion to cell-associated MUC1-ED. Levels of desialylated MUC1-ED were elevated in the bronchoalveolar lavage fluid of mechanically ventilated patients with P. aeruginosa airway colonization. Preincubation of P. aeruginosa with these same ex vivo fluids competitively inhibited bacterial adhesion to airway epithelia, and MUC1-ED immunodepletion completely abrogated their inhibitory activity. These data indicate that a prokaryote, P. aeruginosa, in a ligand-specific manner, mobilizes eukaryotic NEU1 to enhance bacterial pathogenicity, but the host retaliates by releasing MUC1-ED into the airway lumen as a hyperadhesive decoy receptor.
Chronic inflammation and fibrosis are hallmarks of lung pathology of newborn Ureaplasma infection... more Chronic inflammation and fibrosis are hallmarks of lung pathology of newborn Ureaplasma infection. We hypothesized that antenatally acquired Ureaplasma stimulates a chronic inflammatory, profibrotic immune response that contributes to lung injury, altered developmental signaling, and fibrosis. Lung specimens from 125-d gestation baboon newborns ventilated for 14 d that were either infected antenatally with Ureaplasma serovar 1 or noninfected, and 125-d and 140-d gestational controls were obtained from the Baboon BPD Resource Center (San Antonio, TX). Trichrome stain to assess fibrosis and immunohistochemistry for ␣-smooth muscle actin (␣-SMA) and transforming growth factor  1 (TGF 1 ) were performed. Lung homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA) for cytokines [tumor necrosis factor ␣ (TNF␣), interleukin (IL)-1, TGF 1 , oncostatin M (OSM), IL-10, and interferon ␥ (IFN␥)] and the chemokine MCP-1 and by Western blot for Smad2, Smad3, and Smad7. Compared with noninfected ventilated and gestational controls, Ureaplasma-infected lungs demonstrated more extensive fibrosis, increased ␣-SMA and TGF 1 immunostain- ing, and higher concentrations of active TGF 1 , IL-1, and OSM, but no difference in IL-10 levels. There was a trend toward higher Smad2/Smad7 and Smad3/Smad7 ratios in Ureaplasma lung homogenates, consistent with up-regulation of TGF 1 signaling. Collectively, these data suggest that a prolonged proinflammatory response initiated by intrauterine Ureaplasma infection contributes to early fibrosis and altered developmental signaling in the immature lung.
Purpose of Review-Premature activation of aging-associated molecular mechanisms is emerging as an... more Purpose of Review-Premature activation of aging-associated molecular mechanisms is emerging as an important contributor to many diseases, including scleroderma. Among central regulators of the aging process are a group of histone deacetylases called sirtuins (SIRTs). Recent findings implicate these molecules as pathophysiological players in scleroderma skin and lung fibrosis. The goal of this article is to review recent studies on the involvement of SIRTs in scleroderma from the perspective of aging-related molecular mechanisms. Recent Findings-Despite a degree of controversy in this rapidly developing field, the majority of data suggest that SIRT levels are decreased in tissues from patients with scleroderma compared to healthy controls as well as in animal models of scleroderma. Molecular studies reveal several mechanisms through which declining SIRT levels contribute to fibrosis, with the most attention given to modulation of the TGF-β signaling pathway. Activation of SIRTs in cell culture and in animal models elicits antifibrotic effects. Summary-Declining SIRT levels and activity are emerging as pathophysiological contributors to scleroderma. Restoration of SIRTs may be therapeutic in patients with scleroderma.
American Journal of Respiratory Cell and Molecular Biology, Dec 1, 2013
The mechanisms of interstitial lung disease (ILD) remain incompletely understood, although recent... more The mechanisms of interstitial lung disease (ILD) remain incompletely understood, although recent observations have suggested an important contribution by IL-33. Substantial elevations in IL-33 expression were found in the lungs of patients with idiopathic pulmonary fibrosis and scleroderma lung disease, as well as in the bleomycin injury mouse model. Most of the observed IL-33 expression was intracellular and intranuclear, suggesting involvement of the full-length (fl) protein, but not of the proteolytically processed mature IL-33 cytokine. The effects of flIL-33 on mouse lungs were assessed independently and in combination with bleomycin injury, using recombinant adenovirusmediated gene delivery. Bleomycin-induced changes were not affected by gene deficiency of the IL-33 receptor T1/ST2. Combined flIL-33 expression and bleomycin injury exerted a synergistic effect on pulmonary lymphocyte and collagen accumulation, which could be explained by synergistic regulation of the cytokines transforming growth factor-b, IL-6, monocyte chemotactic protein-1, macrophage inflammatory protein-1a, and tumor necrosis factor-a. By contrast, no increase in the levels of the Th2 cytokines IL-4, IL-5, or IL-13 was evident. Moreover, flIL-33 was found to increase the expression of several heat shock proteins (HSPs) significantly, and in particular HSP70, which is known to be associated with ILD. Thus, flIL-33 is a synergistic proinflammatory and profibrotic regulator that acts by stimulating the expression of several non-Th2 cytokines, and activates the expression of HSP70.
tions after transplantation, we analyzed the T-cell repertoire expressed in bronchoalveolar lavag... more tions after transplantation, we analyzed the T-cell repertoire expressed in bronchoalveolar lavage fluids from eleven patients with graft-versus-host disease following BMT. A reverse transcriptase-polymerase chain reaction was used to amplify rearranged TCR transcripts in unfractionated, CD4+, and CD8+ T cells from bronchoalveolar lavage fluids. The relative expression of TCR variable (V) gene families and the diversity of junctional region lengths associated with different AV and BV gene families were analyzed. Nearly all TCR AV and BV gene families were detected in bronchoalveolar lavage cells from BMT recipients. Oligoclonal patterns of TCR junctional region lengths were observed in unfractionated, CD4+, and CD8+ bronchoalveolar T cells. The oligoclonal expansion of bronchoalveolar T cells in patients was confirmed by DNA sequencing. TCRV gene expression is almost completely restored in the lungs of BMT recipients as early as two weeks after transplantation. Increased oligoclonality among TCR gene families suggests either an incomplete restoration of TCR diversity or an antigen-driven expansion of T cells in the lungs of BMT recipients with graft-versus-host disease, not necessarily related to pulmonary infection. Am.
Interleukin (IL)-33 and its receptor ST2 have been recently implicated as critical regulators of ... more Interleukin (IL)-33 and its receptor ST2 have been recently implicated as critical regulators of responses to injury and of ensuing inflammation. The roles of IL-33 and ST2 in pulmonary inflammation and scarring remain unclear. We analyzed bronchoalveolar lavage (BAL) from patients with idiopathic pulmonary fibrosis (IPF), a disease characterized by inflammation, with known elevated levels of IL-8 and excessive collagen deposition in the lungs. IL-33 was not found in BAL from 5 controls but was found in 7 out of 11 IPF samples, at 10.0 ± 3.2 pg/ml. Soluble ST2 was found in BAL from healthy controls at 93.2 ± 82.1 pg/ml, and in all IPF samples at 352.1 ± 135.2 pg/ml (p < 0.05, Mann-Whitney U test). The elevation of IL-33 in BAL suggested that this cytokine may act directly on pulmonary epithelial cells and through this action contribute to inflammation. Cultured human primary pulmonary epithelial cells were stimulated with rhIL-33, and the levels of pro-inflammatory cytokines IL-6, IL-8, MIP-1α, and TNF-α in cell culture media were analyzed by ELISA. Of the analyzed cytokines, only the levels of IL-8 were increased by 2.0 ± 0.2 fold at 24 h and 1.7 ± 0.2 fold at 48 h. In conclusion, levels of IL-33 and ST2 are elevated in the lungs of IPF patients; IL-33 may contribute to inflammation and fibrosis by activating IL-8 production in pulmonary epithelium.
Previous reports have been inconsistent on whether Interleukin (IL)-33 necessarily promotes Th2 e... more Previous reports have been inconsistent on whether Interleukin (IL)-33 necessarily promotes Th2 effects in vivo. This diversity of findings may be due to post-synthetic processing of IL-33. We compared the in vivo effects of full-length mouse (flm) and mature mouse (mm) IL-33 utilizing replication-deficient adenovirus (AdV)-mediated gene delivery. mmIL-33 promoted pulmonary eosinophilia, neutrophilia, and significant elevations in IL-4, IL-5, and IL-13 compared to AdV-NULL-infected controls (p < 0.05 in all cases), whereas flmIL-33 had no such effects. A possibility was considered that flmIL-33 may modulate the effects of a prototypic Th2 cytokine, IL-4. The effects of AdV-mediated gene delivery of IL-4 were compared with the effects of combined flmIL-33 and mIL-4. In the latter case, a bicistronic AdV construct encoding flmIL-33 and mIL-4 was used to ensure co-localization of expression of both cytokines. On day 7 after instillation of the viral particles, IL-4-expressing mice had elevated eosinophils and neutrophils in their BAL, and animals expressing both flmIL-33 and IL-4 had yet significantly more BAL eosinophils and neutrophils compared with IL-4-expressing mice (p < 0.05). Similar potentiating effects of flmIL-33 were observed on IL-4-driven increases in pulmonary cytokines TNF-α, IL-5, IL-13, MCP-1, and in goblet cell hyperplasia. These results suggest that although full-length IL-33 has no independent pro-Th2 effect on the lung, it potentiates such effects of IL-4.
Interstitial lung disease, a combination of pulmonary inflammation and fibrosis, is deadly and oc... more Interstitial lung disease, a combination of pulmonary inflammation and fibrosis, is deadly and occurs idiopathically or as a complication of autoimmune rheumatic diseases (scleroderma, rheumatoid arthritis, poly- and dermatomyositis, lupus). T cells often accumulate in the lungs of such patients. Previous reports suggested that αV-containing integrins may activate TGF-β and facilitate fibrosis. Whether pulmonary T cells utilize such integrins in interstitial lung disease is not clear. Expression of integrins αVβ3 (ITGAVB3) or αVβ5 (ITGAVB5) on pulmonary T cells was observed by double-stain immunofluorescence confocal microscopy in six out of six patients with scleroderma lung disease, as well as in the animal models of pulmonary CCL18 overexpression that manifests in selective T lymphocytic infiltration of the lungs and T cell-dependent pulmonary fibrosis. Flow cytometry of bronchoalveolar lavage T cells confirmed expression of integrins on more than 10% (up to 50%) of pulmonary T cells in 14 of 25 scleroderma patients and in all CCL18-overexpressing mice; Q-PCR experiments confirmed elevated integrin mRNAs in purified BAL T cells. There was no expression of ITGAVB3 or ITGAVB5 on T cells from the lungs of healthy volunteers or control mice. Injections of anti-ITGB3 blocking antibody or genetic deficiency of ITGB3 protected mice from CC18-induced inflammation and fibrosis. Jurkat cells that were forced to overexpress ITGAVB3 or ITGAVB5 induced Smad2 phosphorylation and nuclear translocation, and increases in collagen and α-smooth muscle actin expression in co-cultures with primary lung fibroblasts. Blocking anti-TGF-β antibodies attenuated such regulation in cell co-cultures. Thus, expression of integrins on pulmonary T cells contributes to interstitial lung disease by promoting T cell infiltration, TGF-β activation, and fibrosis.
We have previously shown that IL-4δ2, a naturally occurring in humans and other species splice va... more We have previously shown that IL-4δ2, a naturally occurring in humans and other species splice variant of IL-4, competes with IL-4 for receptor binding and inhibits some of IL-4 effects on lymphocytes and monocytes. Numerous groups reported that the levels and the ratio of IL-4δ2 and IL-4 mRNAs change in immune, inflammatory, and infectious diseases. It has been suggested that recombinant human (rh) IL-4δ2 can be used therapeutically to neutralize the harmful effects of excess IL-4 in vivo, although it was not clear whether IL-4δ2 mRNA expressing cells secrete IL-4δ2 protein. Transfection of HEK293 or Jurkat cells with IL-4δ2-encoding constructs resulted in IL-4δ2 protein secretion confirmed by LC/MS, ELISA, and Western blotting. To investigate whether IL-4δ2 has no independent activity and acts only as an inhibitor of IL-4, we overexpressed human IL-4δ2 in mouse lungs. Adenovirus-mediated gene delivery of IL-4δ2 caused lymphocytic infiltration similar to that in IL-4-overexpressing mice, as well as proinflammatory/Th1 changes in pulmonary milieu, with the induced levels of TNF-α, IL-1, IFN-γ, IL-12p40, and MCP-1 significantly exceeding those induced by gene delivery of IL-4. Germline deficiency of STAT6 had no effect, whereas deficiency of IL-4Rα significantly attenuated IL-4δ2-induced or IL-4-induced changes in the lungs. Stimulation of primary human T cells or PBMC, but not fibroblasts or A549 cells, with rhIL-4δ2 induced phosphorylation of Jak1, Jak3, and Tyk2, but not of STAT6. IL-4δ2 potently induced production of MCP-1 in human T cells and upregulated IL-4δ2 mRNA production in an autocrine fashion by several hundred fold. Thus, IL-4δ2 is secreted as a protein, acts as a potent autocrine regulator of inflammation and immunity in an IL-4Rα-dependent STAT6-independent fashion, and is a potential novel target for future therapies.
Activities of T lymphocytes are centrally regulated by interactions between multiple members of t... more Activities of T lymphocytes are centrally regulated by interactions between multiple members of the TNF/TNF-R family. TRAIL is a member of the TNF family with pro-apoptotic activity. The only signaling TRAIL receptor in mice is death receptor (DR) 5. CCL18, a chemokine with selective chemotactic activity on T lymphocytes, is known for its involvement in pulmonary inflammation and fibrosis associated with autoimmune diseases. We measured soluble TRAIL in bronchoalveolar lavage (BAL) fluids. The levels of TRAIL were significantly elevated (p < 0.01, ANOVA) in BAL from 16 patients with scleroderma lung disease (211±110 pg/ml) compared to 16 patients without lung involvement (115±58 pg/ml), or 8 healthy controls (73±41 pg/ml). To determine whether TRAIL is important for CCL18-induced pulmonary infiltration of lymphocytes, recombinant adenovirus-mediated gene delivery of CCL18 was performed in TRAIL KO, DR5 KO, and WT mice. Overexpression of CCL18 caused profound pulmonary lymphocytic infiltration in WT and TRAIL KO mice, compared to control mice infected with AdV-NULL. In contrast, infiltration of T lymphocytes was completely abrogated in CCL18-expressing DR5 KO mice, based on lung histology. Thus, the levels of TRAIL are elevated in the lungs of patients with autoimmunity-associated inflammation and fibrosis, yet TRAIL does not appear to be involved in the CCL18-mediated T lymphocytic infiltration, whereas its receptor DR5 is required for such T cell response to CCL18.
Theoretical Biology and Medical Modelling, Dec 1, 2012
The theory of speciation is dominated by adaptationist thinking, with less attention to mechanism... more The theory of speciation is dominated by adaptationist thinking, with less attention to mechanisms that do not affect species adaptation. Degeneracythe imperfect specificity of interactions between diverse elements of biological systems and their environmentsis key to the adaptability of populations. A mathematical model was explored in which population and resource were distributed one-dimensionally according to trait value. Resource consumption was degenerateneither strictly location-specific nor location-independent. As a result, the competition for resources among the elements of the population was non-local. Two modeling approaches, a modified differential-integral Verhulstian equation and a cellular automata model, showed similar results: narrower degeneracy led to divergent dynamics with suppression of intermediate forms, whereas broader degeneracy led to suppression of diversifying forms, resulting in population stasis with increasing phenotypic homogeneity. Such behaviors did not increase overall adaptation because they continued after the model populations achieved maximal resource consumption rates, suggesting that degeneracy-driven distributed competition for resources rather than selective pressure toward more efficient resource exploitation was the driving force. The solutions were stable in the presence of limited environmental stochastic variability or heritable phenotypic variability. A conclusion was made that both dynamic diversification and static homogeneity of populations may be outcomes of the same processdistributed competition for resource not affecting the overall adaptationwith the difference between them defined by the spread of trait degeneracy in a given environment. Thus, biological degeneracy is a driving force of both speciation and stasis in biology, which, by themselves, are not necessarily adaptive in nature.
IL-4␦2 is a natural splice variant of IL-4 that lacks the region encoded by the second exon. Nume... more IL-4␦2 is a natural splice variant of IL-4 that lacks the region encoded by the second exon. Numerous reports have suggested that the expression levels of IL-4␦2 change in various diseases, especially those with pulmonary involvement, but the in vivo effects of this splice variant have never been studied. Replication-deficient, AdV-mediated gene delivery of mIL-4␦2 to mouse lungs in vivo was used, and the effects compared with similar adenoviral delivery of mIL-4 or with infection with a noncoding NULL viral construct. Overexpression of IL-4␦2 or IL-4 caused pulmonary infiltration by T and B lymphocytes, whereas in contrast to IL-4, IL-4␦2 did not induce eosinophilia or goblet cell hyperplasia. Microarray analysis of global gene expression revealed that IL-4␦2 and IL-4 had differential effects on gene expression. These splice variants also differentially regulated pulmonary levels of the cytokines TNF-␣, eotaxin, IL-1␣, IFN-␥, and MCP-1, whereas both tended to increase total lung collagen modestly. Pulmonary infiltration by lymphocytes in response to overexpression of IL-4␦2 was attenuated but not abrogated completely by germline deficiency of IL-4R␣ or STAT6, whereas deficiency of endogenous IL-4 had no effect. Thus, IL-4␦2 promotes lymphocytic inflammation in vivo (although differentially from IL-4, in part), and the effects of IL-4␦2 are not mediated by endogenous IL-4. Differential targeting of IL-4␦2 and IL-4 may therefore be considered in developing future therapeutic agents.
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