The mechanisms of mononuclear phagocyte death have been associated with the permissiveness and re... more The mechanisms of mononuclear phagocyte death have been associated with the permissiveness and resistance to mycobacterial replication, but it remains unknown whether or not they help predict the risk of developing TB. To describe the factors associated with the induction of monocyte mitochondrial and membrane damage in response to PPD as well as determine if this type of damage might predict the susceptibility of developing active tuberculosis in a cohort of household contacts (HHCs) from Medellin, Colombia from 2005 to 2008. The prospective cohort study contains 2060 HHCs patients with pulmonary tuberculosis who were meticulously followed for two years. A survey of the socio-demographic, clinical, epidemiological factors and blood samples were collected. Mononuclear cell cultures were stimulated with or without PPD and the type of monocyte death was determined by the flow of cytometry, an indicator was also used for its analysis. Logistic regression was adjusted by the Generalized...
Multifunctional T cells have been shown to be protective in chronic viral infections. In mycobact... more Multifunctional T cells have been shown to be protective in chronic viral infections. In mycobacterial infections, however, evidence for a protective role of multifunctional T cells remains inconclusive. Short-term cultures of peripheral blood mononuclear cells stimulated with the Mycobacterium tuberculosis RD1 antigens 6-kDa early secretory antigenic target (ESAT6) and 10-kDa culture filtrate antigen (CFP10), which are induced in the early infection phase, have been mainly used to assess T cell multifunctionality, although long-term culture assays have been proposed to be more sensitive than short-term assays for assessment of memory T cells, which are essential for long-term immunity. Here we used a long-term culture assay system to study the T cell immune responses to the M. tuberculosis latency-associated DosR antigens and reactivation-associated Rpf antigens, compared to ESAT6 and CFP10, in patients with pulmonary tuberculosis (PTB) and household contacts of PTB patients with l...
Our aim was to characterize glomerular monocytes (Mo) infiltration and to correlate them with per... more Our aim was to characterize glomerular monocytes (Mo) infiltration and to correlate them with peripheral circulating Mo subsets and severity of lupus nephritis (LN). Methods. We evaluated 48 LN biopsy samples from a referral hospital. Recognition of Mo cells was done using microscopic view and immunohistochemistry stain with CD14 and CD16. Based on the number of cells, we classified LN samples as low degree of diffuse infiltration (<5 cells) and high degree of diffuse infiltration (≥5 cells). Immunophenotyping of peripheral Mo subsets was done using flow cytometry. Results. Mean age was 34.0±11.7 years and the mean SLEDAI was 17.5±6.9. The most common SLE manifestations were proteinuria (91%) and hypocomplementemia (75%). Severe LN was found in 70% of patients (Class III, 27%; Class IV, 43%). Severe LN patients and patients with higher grade of CD16+ infiltration had lower levels of nonclassical (CD14+CD16++) Mo in peripheral blood. Conclusions. Our results might suggest that tho...
Archivum immunologiae et therapiae experimentalis, Jan 20, 2018
Diseases caused by dengue virus (DENV) are a major public health problem worldwide, considered on... more Diseases caused by dengue virus (DENV) are a major public health problem worldwide, considered one of the infections with more prevalence in tropical and subtropical zones of the world. Despite the intense research in the pathogenesis of DENV, this feature is not well understood. One of the main target cells for DENV infection is monocytes; these phagocytes can play a dual role, since they are essential to control viremia, but they also participate in the induction of tissue damage during DENV infection. Monocytes produce different pro-inflammatory cytokines and chemokines in response to infection, and also mediate endothelial damage. In peripheral blood, monocytes can be divided into three different subpopulations, namely classical, intermediate and non-classical, which differ in frequency, cytokine production, among others. Studies in the last years suggest that non-classical monocytes have higher affinity for microvasculature endothelium compared to other type of monocytes, which...
Microparticles (MPs) are vesicles derived from the plasma membrane of different cells, are consid... more Microparticles (MPs) are vesicles derived from the plasma membrane of different cells, are considered a source of circulating autoantigens, and can form immune complexes (MPs-ICs). The number of MPs and MPs-ICs increases in patients with systemic lupus erythematosus (SLE). MPs activate myeloid cells by inducing IL-6 and TNF-α in both SLE and other diseases. Therefore, we propose that the recognition of MPs-ICs by monocytes rather that MPs may define their phenotype and contribute to the inflammatory process in patients with SLE. Thus, the aims of this study were to evaluate the association among circulating MPs-ICs from different cell sources, alterations observed in monocyte subsets, and disease activity in patients with SLE and to establish whether monocytes bind and respond to MPs-ICs. Circulating MPs and monocyte subsets were characterized in 60 patients with SLE and 60 healthy controls (HCs) using multiparametric flow cytometry. Patients had higher MP counts and frequencies of ...
The evidence regarding the role of regulatory B cells (Breg) in atherosclerosis are scarce, and t... more The evidence regarding the role of regulatory B cells (Breg) in atherosclerosis are scarce, and there are contradictory data about their atheroprotective properties. Due to the demonstrated protective function of Breg in different inflammatory diseases mainly through interleukin-10 (IL-10) production, the knowledge of their participation in atherosclerosis immunopathology would be very valuable. To further study which B cell subsets participate in IL-10 production and their regulatory role, splenocytes from apolipoprotein-E-deficient mice were evaluated by ex vivo and in vitro cultures. Atherosclerotic mice had increased frequency of IL-10(+) B cells, which presented high CD1d, CD19, and IgM, but variable CD5, CD21, and CD23 expression. IL-10(+) B cells were not enriched in B cell subsets previously reported as Breg. Increased frequency of IL-10(+) B cells with transitional 1-like (T1-like) and follicular (FO) and reduced CD5(+) and marginal zone (MZ) phenotypes were observed ex viv...
The release of DNA into the extracellular milieu by neutrophil during a process called NETosis ha... more The release of DNA into the extracellular milieu by neutrophil during a process called NETosis has been postulated as an additional source of autoantigens; a process believed to be important in the pathogenesis of some autoimmune disease, such as Systemic Lupus Erythematosus (SLE). However, it is not established if the B and T cells undergo the release of DNA to the extracellular milleu, in response to different stimuli. In this study, it was observed that, the treatment of B and T cells with PMA, ionomycin, and the serum from patients with SLE induced the extracellular DNA presence in B and T cells. These findings suggest that the phenomenon were similar to those observed in neutrophil's Etosis; B and T cells also released their DNA into the extracellular milieu. The findings express that serum from patients with SLE and SLEDAI ≤ 8 triggers the release of extracellular DNA in neutrophils, B and T cells, that suggested the presence of soluble factors in the serum that favored th...
Patients with systemic autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus e... more Patients with systemic autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are prone to develop atherosclerosis and cardiovascular diseases five times more often than the general population; this increase in frequency could be partially explained by an increase in the macrovasculature endothelial damage. In these autoimmune diseases, a microvascular endothelial injury has also been reported in different organs and tissues, especially in sites where ultrafiltration processes occur. Different components that are characteristic to the immunopathology of RA and SLE could be involved in the endothelial cell activation, permeability increase, functional alteration, and vascular injury. Circulating immune complexes (IC) detected in SLE and RA have been proposed to participate in the endothelial injury. In the vascular environment, IC can generate different responses that could be mediated by monocytes, because these cells have patrolling and monitor...
Los fagocitos mononucleares, en particular los monocitos y los macrófagos, han sido considerados ... more Los fagocitos mononucleares, en particular los monocitos y los macrófagos, han sido considerados los blancos primarios de la infección por Mycobacterium tuberculosis y, a su vez, las principales células efectoras y reservorios de la micobacteria. La heterogeneidad de estas células, así como su plasticidad, hacen que las respuestas ante la infección sean diversas y complejas. Las diferencias que presentan los fagocitos mononucleares de animales naturalmente resistentes a la infección, la expresión de los genes asociados al control de las infecciones micobacterianas y las discrepancias que se observan entre los monocitos en circulación de los pacientes con tuberculosis y los controles sanos en la expresión de CD14, CD36 y HLA-DR, así como en la muerte celular, nos ha sugerido que puede haber alteraciones en la distribución de las subpoblaciones de monocitos o en su estado de madurez. En humanos, las subpoblaciones de monocitos de sangre periférica se definieron inicialmente de acuerdo con la expresión de las moléculas de superficie CD14 y CD16. Hay dos tipos principales de monocitos, unos con alta expresión de CD14 y carentes de CD16 (CD14 + CD16-) y otros con baja expresión de CD14 y que expresan CD16 (CD14 + CD16 +). En los pacientes con tuberculosis hay alteraciones en los recuentos de las subpoblaciones de monocitos, lo que nos hace considerar que el entendimiento de estos eventos podría ser fundamental en la comprensión de la inmunopatogénesis de esta enfermedad.
The heterogeneity of mononuclear phagocytes, partially explained by cell differentiation, influen... more The heterogeneity of mononuclear phagocytes, partially explained by cell differentiation, influences the activation of innate responses. It has been reported that Mycobacterium tuberculosis inhibits monocyte differentiation into either dendritic cells or macrophages. To evaluate whether the activation of effector mechanisms against M. tuberculosis differ between less and more differentiated mononuclear phagocytes, we compared monocytes differentiated in vitro for 24 h (MON24) and 120 h (MDM120) infected with M. tuberculosis H37Rv, H37Ra and the clinical isolate UT127 at different multiplicity of infection. MDM120 phagocytosed more M. tuberculosis, inhibited mycobacterial growth and did not die in response to the infection, compared with MON24. In contrast, MON24 become Annexin V and Propidium iodide positive after 36 h of M. tuberculosis infection. Although, there were striking differences between MON24 and MDM120, there were also some differences in the response to the mycobacterial strains used. Finally, in MDM120 infected with M. tuberculosis H37Rv, a lower percentage of mycobacterial phagosomes accumulated transferrin and a higher percentage co-localized with cathelicidin than in MON24. These results demonstrate that innate responses induced by M. tuberculosis depends upon the stage of differentiation of mononuclear phagocytes and support that terminally differentiated cells are more efficient anti-mycobacterial effectors than the less differentiated ones.
Monocytes from tuberculosis patients exhibit functional and phenotypical alterations compared wit... more Monocytes from tuberculosis patients exhibit functional and phenotypical alterations compared with healthy controls. To determine whether these discrepancies can be explained by changes in monocyte subsets, the expression of CD14 and CD16 was evaluated in tuberculosis patients and healthy controls; additionally, some markers related to the mononuclear phagocytes maturation, differentiation and function, such as CD1a, CD1c, CD11b, CD11c, CD13, CD33, CD36, CD40, CD64, CD68, CD80, CD83, CD86, HLA-DR, CCR2, CCR5, and non-specific esterases (NSE) were determined in monocyte subsets. Patients had increased percentage of circulating CD14(Hi)CD16(+) and CD14(Lo)CD16(+) monocytes. The percentage of monocytes expressing CD11b, CD36, CD64, CD68, CD80, CD86, CCR2 and NSE was lower in CD14(Hi)CD16(+) and CD14(Lo)CD16(+) cells than in CD14(Hi)CD16(-) monocytes. M. tuberculosis infected CD16(+) monocytes produced more TNF-α and less IL-10 than CD16(-) cells at 6 h post-infection. Isolated CD16(+) monocytes spontaneously underwent apoptosis during differentiation into macrophages; in contrast to CD16(-) monocytes that became differentiated into monocyte-derived macrophages (MDM) with a minimal induction of cell death. In addition, there were more Annexin V and propidium iodide positive monocytes in the CD16(+) subset infected with live M. tuberculosis at 24 h than CD16(-) monocytes. Under the culture conditions established for this study, the monocyte subsets did not differentiate into dendritic cells. These results show that tuberculosis patients have an augmented frequency of CD16(+) circulating monocytes which are more prone to produce TNF-α and to undergo cell death in response to M. tuberculosis infection.
Plants are often exposed to external biotic or abiotic agents that can damage cells. Biotic agent... more Plants are often exposed to external biotic or abiotic agents that can damage cells. Biotic agents include molecules produced by pathogens, and abiotic agents include ultraviolet radiation, heavy metals and xenobiotic agents such as herbicides. Because of the importance of abiotic stresses and the limited knowledge of the defense responses of plants to stresses, a study was conducted using flow cytometry to evaluate endocellular events in protoplasts of two tomato species, Lycopersicon hirsutum and Lycopersicon esculentum, following exposure to 10 mM CuCl 2 and 1% paraquat. During the first 30 min of exposure to 10 mM CuCl 2, mean fluorescence intensity values in both species decreased by more than 50% compared to the untreated control. During the first 30 min of paraquat treatment, the production of reactive oxygen species, evaluated as the incidence of protoplasts in which the superoxide anion was present, was 32.9 % and 25.4%, respectively, for L. hirsutum and L. esculentum. Hyperpolarization of the mitochondria for both tomatoes species was observed during the first 2 h. The absence of early membrane damage and the markedly detrimental effects of the treatments on the mitochondria suggest that additional mechanisms which lead to cell death may be involved in these processes, and that these mechanisms may be associated with apoptosis.
The mechanisms of mononuclear phagocyte death have been associated with the permissiveness and re... more The mechanisms of mononuclear phagocyte death have been associated with the permissiveness and resistance to mycobacterial replication, but it remains unknown whether or not they help predict the risk of developing TB. To describe the factors associated with the induction of monocyte mitochondrial and membrane damage in response to PPD as well as determine if this type of damage might predict the susceptibility of developing active tuberculosis in a cohort of household contacts (HHCs) from Medellin, Colombia from 2005 to 2008. The prospective cohort study contains 2060 HHCs patients with pulmonary tuberculosis who were meticulously followed for two years. A survey of the socio-demographic, clinical, epidemiological factors and blood samples were collected. Mononuclear cell cultures were stimulated with or without PPD and the type of monocyte death was determined by the flow of cytometry, an indicator was also used for its analysis. Logistic regression was adjusted by the Generalized...
Multifunctional T cells have been shown to be protective in chronic viral infections. In mycobact... more Multifunctional T cells have been shown to be protective in chronic viral infections. In mycobacterial infections, however, evidence for a protective role of multifunctional T cells remains inconclusive. Short-term cultures of peripheral blood mononuclear cells stimulated with the Mycobacterium tuberculosis RD1 antigens 6-kDa early secretory antigenic target (ESAT6) and 10-kDa culture filtrate antigen (CFP10), which are induced in the early infection phase, have been mainly used to assess T cell multifunctionality, although long-term culture assays have been proposed to be more sensitive than short-term assays for assessment of memory T cells, which are essential for long-term immunity. Here we used a long-term culture assay system to study the T cell immune responses to the M. tuberculosis latency-associated DosR antigens and reactivation-associated Rpf antigens, compared to ESAT6 and CFP10, in patients with pulmonary tuberculosis (PTB) and household contacts of PTB patients with l...
Our aim was to characterize glomerular monocytes (Mo) infiltration and to correlate them with per... more Our aim was to characterize glomerular monocytes (Mo) infiltration and to correlate them with peripheral circulating Mo subsets and severity of lupus nephritis (LN). Methods. We evaluated 48 LN biopsy samples from a referral hospital. Recognition of Mo cells was done using microscopic view and immunohistochemistry stain with CD14 and CD16. Based on the number of cells, we classified LN samples as low degree of diffuse infiltration (<5 cells) and high degree of diffuse infiltration (≥5 cells). Immunophenotyping of peripheral Mo subsets was done using flow cytometry. Results. Mean age was 34.0±11.7 years and the mean SLEDAI was 17.5±6.9. The most common SLE manifestations were proteinuria (91%) and hypocomplementemia (75%). Severe LN was found in 70% of patients (Class III, 27%; Class IV, 43%). Severe LN patients and patients with higher grade of CD16+ infiltration had lower levels of nonclassical (CD14+CD16++) Mo in peripheral blood. Conclusions. Our results might suggest that tho...
Archivum immunologiae et therapiae experimentalis, Jan 20, 2018
Diseases caused by dengue virus (DENV) are a major public health problem worldwide, considered on... more Diseases caused by dengue virus (DENV) are a major public health problem worldwide, considered one of the infections with more prevalence in tropical and subtropical zones of the world. Despite the intense research in the pathogenesis of DENV, this feature is not well understood. One of the main target cells for DENV infection is monocytes; these phagocytes can play a dual role, since they are essential to control viremia, but they also participate in the induction of tissue damage during DENV infection. Monocytes produce different pro-inflammatory cytokines and chemokines in response to infection, and also mediate endothelial damage. In peripheral blood, monocytes can be divided into three different subpopulations, namely classical, intermediate and non-classical, which differ in frequency, cytokine production, among others. Studies in the last years suggest that non-classical monocytes have higher affinity for microvasculature endothelium compared to other type of monocytes, which...
Microparticles (MPs) are vesicles derived from the plasma membrane of different cells, are consid... more Microparticles (MPs) are vesicles derived from the plasma membrane of different cells, are considered a source of circulating autoantigens, and can form immune complexes (MPs-ICs). The number of MPs and MPs-ICs increases in patients with systemic lupus erythematosus (SLE). MPs activate myeloid cells by inducing IL-6 and TNF-α in both SLE and other diseases. Therefore, we propose that the recognition of MPs-ICs by monocytes rather that MPs may define their phenotype and contribute to the inflammatory process in patients with SLE. Thus, the aims of this study were to evaluate the association among circulating MPs-ICs from different cell sources, alterations observed in monocyte subsets, and disease activity in patients with SLE and to establish whether monocytes bind and respond to MPs-ICs. Circulating MPs and monocyte subsets were characterized in 60 patients with SLE and 60 healthy controls (HCs) using multiparametric flow cytometry. Patients had higher MP counts and frequencies of ...
The evidence regarding the role of regulatory B cells (Breg) in atherosclerosis are scarce, and t... more The evidence regarding the role of regulatory B cells (Breg) in atherosclerosis are scarce, and there are contradictory data about their atheroprotective properties. Due to the demonstrated protective function of Breg in different inflammatory diseases mainly through interleukin-10 (IL-10) production, the knowledge of their participation in atherosclerosis immunopathology would be very valuable. To further study which B cell subsets participate in IL-10 production and their regulatory role, splenocytes from apolipoprotein-E-deficient mice were evaluated by ex vivo and in vitro cultures. Atherosclerotic mice had increased frequency of IL-10(+) B cells, which presented high CD1d, CD19, and IgM, but variable CD5, CD21, and CD23 expression. IL-10(+) B cells were not enriched in B cell subsets previously reported as Breg. Increased frequency of IL-10(+) B cells with transitional 1-like (T1-like) and follicular (FO) and reduced CD5(+) and marginal zone (MZ) phenotypes were observed ex viv...
The release of DNA into the extracellular milieu by neutrophil during a process called NETosis ha... more The release of DNA into the extracellular milieu by neutrophil during a process called NETosis has been postulated as an additional source of autoantigens; a process believed to be important in the pathogenesis of some autoimmune disease, such as Systemic Lupus Erythematosus (SLE). However, it is not established if the B and T cells undergo the release of DNA to the extracellular milleu, in response to different stimuli. In this study, it was observed that, the treatment of B and T cells with PMA, ionomycin, and the serum from patients with SLE induced the extracellular DNA presence in B and T cells. These findings suggest that the phenomenon were similar to those observed in neutrophil's Etosis; B and T cells also released their DNA into the extracellular milieu. The findings express that serum from patients with SLE and SLEDAI ≤ 8 triggers the release of extracellular DNA in neutrophils, B and T cells, that suggested the presence of soluble factors in the serum that favored th...
Patients with systemic autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus e... more Patients with systemic autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are prone to develop atherosclerosis and cardiovascular diseases five times more often than the general population; this increase in frequency could be partially explained by an increase in the macrovasculature endothelial damage. In these autoimmune diseases, a microvascular endothelial injury has also been reported in different organs and tissues, especially in sites where ultrafiltration processes occur. Different components that are characteristic to the immunopathology of RA and SLE could be involved in the endothelial cell activation, permeability increase, functional alteration, and vascular injury. Circulating immune complexes (IC) detected in SLE and RA have been proposed to participate in the endothelial injury. In the vascular environment, IC can generate different responses that could be mediated by monocytes, because these cells have patrolling and monitor...
Los fagocitos mononucleares, en particular los monocitos y los macrófagos, han sido considerados ... more Los fagocitos mononucleares, en particular los monocitos y los macrófagos, han sido considerados los blancos primarios de la infección por Mycobacterium tuberculosis y, a su vez, las principales células efectoras y reservorios de la micobacteria. La heterogeneidad de estas células, así como su plasticidad, hacen que las respuestas ante la infección sean diversas y complejas. Las diferencias que presentan los fagocitos mononucleares de animales naturalmente resistentes a la infección, la expresión de los genes asociados al control de las infecciones micobacterianas y las discrepancias que se observan entre los monocitos en circulación de los pacientes con tuberculosis y los controles sanos en la expresión de CD14, CD36 y HLA-DR, así como en la muerte celular, nos ha sugerido que puede haber alteraciones en la distribución de las subpoblaciones de monocitos o en su estado de madurez. En humanos, las subpoblaciones de monocitos de sangre periférica se definieron inicialmente de acuerdo con la expresión de las moléculas de superficie CD14 y CD16. Hay dos tipos principales de monocitos, unos con alta expresión de CD14 y carentes de CD16 (CD14 + CD16-) y otros con baja expresión de CD14 y que expresan CD16 (CD14 + CD16 +). En los pacientes con tuberculosis hay alteraciones en los recuentos de las subpoblaciones de monocitos, lo que nos hace considerar que el entendimiento de estos eventos podría ser fundamental en la comprensión de la inmunopatogénesis de esta enfermedad.
The heterogeneity of mononuclear phagocytes, partially explained by cell differentiation, influen... more The heterogeneity of mononuclear phagocytes, partially explained by cell differentiation, influences the activation of innate responses. It has been reported that Mycobacterium tuberculosis inhibits monocyte differentiation into either dendritic cells or macrophages. To evaluate whether the activation of effector mechanisms against M. tuberculosis differ between less and more differentiated mononuclear phagocytes, we compared monocytes differentiated in vitro for 24 h (MON24) and 120 h (MDM120) infected with M. tuberculosis H37Rv, H37Ra and the clinical isolate UT127 at different multiplicity of infection. MDM120 phagocytosed more M. tuberculosis, inhibited mycobacterial growth and did not die in response to the infection, compared with MON24. In contrast, MON24 become Annexin V and Propidium iodide positive after 36 h of M. tuberculosis infection. Although, there were striking differences between MON24 and MDM120, there were also some differences in the response to the mycobacterial strains used. Finally, in MDM120 infected with M. tuberculosis H37Rv, a lower percentage of mycobacterial phagosomes accumulated transferrin and a higher percentage co-localized with cathelicidin than in MON24. These results demonstrate that innate responses induced by M. tuberculosis depends upon the stage of differentiation of mononuclear phagocytes and support that terminally differentiated cells are more efficient anti-mycobacterial effectors than the less differentiated ones.
Monocytes from tuberculosis patients exhibit functional and phenotypical alterations compared wit... more Monocytes from tuberculosis patients exhibit functional and phenotypical alterations compared with healthy controls. To determine whether these discrepancies can be explained by changes in monocyte subsets, the expression of CD14 and CD16 was evaluated in tuberculosis patients and healthy controls; additionally, some markers related to the mononuclear phagocytes maturation, differentiation and function, such as CD1a, CD1c, CD11b, CD11c, CD13, CD33, CD36, CD40, CD64, CD68, CD80, CD83, CD86, HLA-DR, CCR2, CCR5, and non-specific esterases (NSE) were determined in monocyte subsets. Patients had increased percentage of circulating CD14(Hi)CD16(+) and CD14(Lo)CD16(+) monocytes. The percentage of monocytes expressing CD11b, CD36, CD64, CD68, CD80, CD86, CCR2 and NSE was lower in CD14(Hi)CD16(+) and CD14(Lo)CD16(+) cells than in CD14(Hi)CD16(-) monocytes. M. tuberculosis infected CD16(+) monocytes produced more TNF-α and less IL-10 than CD16(-) cells at 6 h post-infection. Isolated CD16(+) monocytes spontaneously underwent apoptosis during differentiation into macrophages; in contrast to CD16(-) monocytes that became differentiated into monocyte-derived macrophages (MDM) with a minimal induction of cell death. In addition, there were more Annexin V and propidium iodide positive monocytes in the CD16(+) subset infected with live M. tuberculosis at 24 h than CD16(-) monocytes. Under the culture conditions established for this study, the monocyte subsets did not differentiate into dendritic cells. These results show that tuberculosis patients have an augmented frequency of CD16(+) circulating monocytes which are more prone to produce TNF-α and to undergo cell death in response to M. tuberculosis infection.
Plants are often exposed to external biotic or abiotic agents that can damage cells. Biotic agent... more Plants are often exposed to external biotic or abiotic agents that can damage cells. Biotic agents include molecules produced by pathogens, and abiotic agents include ultraviolet radiation, heavy metals and xenobiotic agents such as herbicides. Because of the importance of abiotic stresses and the limited knowledge of the defense responses of plants to stresses, a study was conducted using flow cytometry to evaluate endocellular events in protoplasts of two tomato species, Lycopersicon hirsutum and Lycopersicon esculentum, following exposure to 10 mM CuCl 2 and 1% paraquat. During the first 30 min of exposure to 10 mM CuCl 2, mean fluorescence intensity values in both species decreased by more than 50% compared to the untreated control. During the first 30 min of paraquat treatment, the production of reactive oxygen species, evaluated as the incidence of protoplasts in which the superoxide anion was present, was 32.9 % and 25.4%, respectively, for L. hirsutum and L. esculentum. Hyperpolarization of the mitochondria for both tomatoes species was observed during the first 2 h. The absence of early membrane damage and the markedly detrimental effects of the treatments on the mitochondria suggest that additional mechanisms which lead to cell death may be involved in these processes, and that these mechanisms may be associated with apoptosis.
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Papers by Mauricio Rojas