Papers by Samuel Belgique
JAMA Surgery, 2021
IMPORTANCE Inhaled nitric oxide (iNO) is commonly administered for selectively inhaled pulmonary ... more IMPORTANCE Inhaled nitric oxide (iNO) is commonly administered for selectively inhaled pulmonary vasodilation and prevention of oxidative injury after lung transplant (LT). Inhaled epoprostenol (iEPO) has been introduced worldwide as a cost-saving alternative to iNO without high-grade evidence for this indication. OBJECTIVE To investigate whether the use of iEPO will lead to similar rates of severe/grade 3 primary graft dysfunction (PGD-3) after adult LT when compared with use of iNO. DESIGN, SETTING, AND PARTICIPANTS This health system-funded, randomized, blinded (to participants, clinicians, data managers, and the statistician), parallel-designed, equivalence clinical trial included 201 adult patients who underwent single or bilateral LT between May 30, 2017, and March 21, 2020. Patients were grouped into 5 strata according to key prognostic clinical features and randomized per stratum to receive either iNO or iEPO at the time of LT via 1:1 treatment allocation. INTERVENTIONS Treatment with iNO or iEPO initiated in the operating room before lung allograft reperfusion and administered continously until cessation criteria met in the intensive care unit (ICU). MAIN OUTCOMES AND MEASURES The primary outcome was PGD-3 development at 24, 48, or 72 hours after LT. The primary analysis was for equivalence using a two one-sided test (TOST) procedure (90% CI) with a margin of 19% for between-group PGD-3 risk difference. Secondary outcomes included duration of mechanical ventilation, hospital and ICU lengths of stay, incidence and severity of acute kidney injury, postoperative tracheostomy placement, and in-hospital, 30-day, and 90-day mortality rates. An intention-to-treat analysis was performed for the primary and secondary outcomes, supplemented by per-protocol analysis for the primary outcome. RESULTS A total of 201 randomized patients met eligibility criteria at the time of LT (129 men [64.2%]). In the intention-to-treat population, 103 patients received iEPO and 98 received iNO. The primary outcome occurred in 46 of 103 patients (44.7%) in the iEPO group and 39 of 98 (39.8%) in the iNO group, leading to a risk difference of 4.9% (TOST 90% CI,-6.4% to 16.2%; P = .02 for equivalence). There were no significant between-group differences for secondary outcomes. CONCLUSIONS AND RELEVANCE Among patients undergoing LT, use of iEPO was associated with similar risks for PGD-3 development and other postoperative outcomes compared with the use of iNO.
The International Journal of Developmental Biology, 2015
Claudin 6 (Cldn6) is a tetraspanin protein expressed by barrier epithelial cells. In order to ass... more Claudin 6 (Cldn6) is a tetraspanin protein expressed by barrier epithelial cells. In order to assess the effects of persistent tight junctions involving Cldn6 during lung development, a doxycycline (dox)-inducible conditional transgenic mouse was generated that up-regulates Cldn6 in the distal lung. Pups had unlimited access to dox from conception until sacrifice date at embryonic day (E) 18.5. Quantitative PCR, immunoblotting, and immunohistochemistry revealed significantly elevated Cldn6 expression in transgenic mice compared to non-transgenic controls. There were no differences in terms of lung size, lung weight, or whole body weight at the time of necropsy. Histological evaluations led to the discovery that E18.5 Cldn6 transgenic pups appeared to be in the early canalicular stage of development coincident with fewer, thickened respiratory airspaces. In contrast, controls appeared to have entered the saccular stage characterized by thin airspace walls and spherical architecture. Immunostaining for transcriptional regulators including TTF-1 and FoxA2 was conducted to assess cell differentiation and specific cell types were identified via staining for pro-surfactant protein C (alveolar type II epithelial cells) or Clara Cell Secretory Protein (cub or Clara cells). Lastly, cell turnover was qualitatively measured via staining for cell proliferation or apoptosis. These data suggest that Cldn6 is an important junctional protein potentially involved in the programming of epithelial cells during lung development. Furthermore, genetic down-regulation of Cldn6 as development proceeds may influence differentiation observed in the transition from the canalicular to the saccular lung.
Experimental lung research, Jan 16, 2016
Chronic obstructive pulmonary disease is a condition involving perturbed barrier integrity coinci... more Chronic obstructive pulmonary disease is a condition involving perturbed barrier integrity coincident with both emphysema and inflammation of the airways, and smoking is considered a major risk factor. Claudins (Cldns) stabilize barriers and contribute to tight junctions by preventing paracellular transport of extracellular fluid constituents. To determine Cldn6 was differentially influenced by tobacco smoke, Cldn6 was evaluated in cells and tissues by q-PCR, immunoblotting, and immunohistochemistry following exposure. Cldn6 transcriptional regulation was also assessed using luciferase reporter constructs. Q-PCR and immunoblotting revealed that Cldn6 was decreased in alveolar type II-like epithelial cells (A549) and primary small airway epithelial cells when exposed to cigarette smoke extract (CSE). Cldn6 was also markedly decreased in the lungs of mice exposed to acute tobacco smoke delivered by a nose-only automated smoke machine compared to controls. Luciferase reporter assays in...
Respiratory Research, 2014
Background: Claudins are transmembrane proteins expressed in tight junctions that prevent paracel... more Background: Claudins are transmembrane proteins expressed in tight junctions that prevent paracellular transport of extracellular fluid and a variety of other substances. However, the expression profile of Claudin-6 (Cldn6) in the developing lung has not been characterized. Methods and results: Cldn6 expression was determined during important periods of lung organogenesis by microarray analysis, qPCR and immunofluorescence. Expression patterns were confirmed to peak at E12.5 and diminish as lung development progressed. Immunofluorescence revealed that Cldn6 was detected in cells that also express TTF-1 and FoxA2, two critical transcriptional regulators of pulmonary branching morphogenesis. Cldn6 was also observed in cells that express Sox2 and Sox9, factors that influence cell differentiation in the proximal and distal lung, respectively. In order to assess transcriptional control of Cldn6, 0.5, 1.0, and 2.0-kb of the proximal murine Cldn6 promoter was ligated into a luciferase reporter and co-transfected with expression vectors for TTF-1 or two of its important transcriptional co-regulators, FoxA2 and Gata-6. In almost every instance, TTF-1, FoxA2, and Gata-6 activated gene transcription in cell lines characteristic of proximal airway epithelium (Beas2B) and distal alveolar epithelium (A-549). Conclusions: These data revealed for the first time that Cldn6 might be an important tight junctional component expressed by pulmonary epithelium during lung organogenesis. Furthermore, Cldn6-mediated aspects of cell differentiation may describe mechanisms of lung perturbation coincident with impaired cell junctions and abnormal membrane permeability.
Purpose: Chronic obstructive pulmonary disease is a condition involving perturbed barrier integri... more Purpose: Chronic obstructive pulmonary disease is a condition involving perturbed barrier integrity coincident with both emphysema and inflammation of the airways, and smoking is considered a major risk factor. Claudins (Cldns) stabilize barriers and contribute to tight junctions by preventing paracellular transport of extracellular fluid constituents. Methods: To determine Cldn6 was differentially influenced by tobacco smoke, Cldn6 was evaluated in cells and tissues by q-PCR, immunoblotting, and immunohistochemistry following exposure. Cldn6 transcriptional regulation was also assessed using luciferase reporter constructs. Results: Q-PCR and immunoblotting revealed that Cldn6 was decreased in alveolar type II-like epithelial cells (A549) and primary small airway epithelial cells when exposed to cigarette smoke extract (CSE). Cldn6 was also markedly decreased in the lungs of mice exposed to acute tobacco smoke delivered by a nose-only automated smoke machine compared to controls. Luciferase reporter assays incorporating 0.5-kb, 1.0-kb, or 2.0-kb of the Cldn6 promoter revealed decreased transcription of Cldn6 following exposure to CSE. Cldn6 transcriptional regulation was also assessed in hypoxic conditions due to low oxygen tension observed during smoking. Hypoxia and hypoxia inducible factor-1 alpha caused decreased transcription of the Cldn6 gene via interactions with putative response elements in the proximal promoter sequence. Conclusions: These data reveal that tight junctional proteins such as Cldn6 are differentially regulated by tobacco-smoke exposure and that Cldns are potentially targeted when epithelial cells respond to tobacco smoke. Further research may show that Cldns expressed in tight junctions between parenchymal cells contribute to impaired structural integrity of the lung coincident with smoking.
Claudin 6 (Cldn6) is a tetraspanin protein expressed by barrier epithelial cells. In order to ass... more Claudin 6 (Cldn6) is a tetraspanin protein expressed by barrier epithelial cells. In order to assess the effects of persistent tight junctions involving Cldn6 during lung development, a doxycycline (dox)-inducible conditional transgenic mouse was generated that up-regulates Cldn6 in the distal lung. Pups had unlimited access to dox from conception until sacrifice date at embryonic day (E) 18.5. Quantitative PCR, immunoblotting, and immunohistochemistry revealed significantly elevated Cldn6 expression in transgenic mice compared to non-transgenic controls. There were no differences in terms of lung size, lung weight, or whole body weight at the time of necropsy. Histological evaluations led to the discovery that E18.5 Cldn6 transgenic pups appeared to be in the early canalicular stage of development coincident with fewer, thickened respiratory airspaces. In contrast, controls appeared to have entered the saccular stage characterized by thin airspace walls and spherical architecture. Immunostaining for transcriptional regulators including TTF-1 and FoxA2 was conducted to assess cell differentiation and specific cell types were identified via staining for pro-surfactant protein C (alveolar type II epithelial cells) or Clara Cell Secretory Protein (cub or Clara cells). Lastly, cell turnover was qualitatively measured via staining for cell proliferation or apoptosis. These data suggest that Cldn6 is an important junctional protein potentially involved in the programming of epithelial cells during lung development. Furthermore, genetic down-regulation of Cldn6 as development proceeds may influence differentiation observed in the transition from the canalicular to the saccular lung.
Background
Claudins are transmembrane proteins expressed in tight junctions that prevent paracel... more Background
Claudins are transmembrane proteins expressed in tight junctions that prevent paracellular transport of extracellular fluid and a variety of other substances. However, the expression profile of Claudin-6 (Cldn6) in the developing lung has not been characterized.
Methods and results
Cldn6 expression was determined during important periods of lung organogenesis by microarray analysis, qPCR and immunofluorescence. Expression patterns were confirmed to peak at E12.5 and diminish as lung development progressed. Immunofluorescence revealed that Cldn6 was detected in cells that also express TTF-1 and FoxA2, two critical transcriptional regulators of pulmonary branching morphogenesis. Cldn6 was also observed in cells that express Sox2 and Sox9, factors that influence cell differentiation in the proximal and distal lung, respectively. In order to assess transcriptional control of Cldn6, 0.5, 1.0, and 2.0-kb of the proximal murine Cldn6 promoter was ligated into a luciferase reporter and co-transfected with expression vectors for TTF-1 or two of its important transcriptional co-regulators, FoxA2 and Gata-6. In almost every instance, TTF-1, FoxA2, and Gata-6 activated gene transcription in cell lines characteristic of proximal airway epithelium (Beas2B) and distal alveolar epithelium (A-549).
Conclusions
These data revealed for the first time that Cldn6 might be an important tight junctional component expressed by pulmonary epithelium during lung organogenesis. Furthermore, Cldn6-mediated aspects of cell differentiation may describe mechanisms of lung perturbation coincident with impaired cell junctions and abnormal membrane permeability.
Claudin 6 (Cldn6) is a tetraspanin protein expressed by barrier epithelial cells. In order to ass... more Claudin 6 (Cldn6) is a tetraspanin protein expressed by barrier epithelial cells. In order to assess the effects of persistent tight junctions involving Cldn6 during lung development, a doxycycline (dox)-inducible conditional transgenic mouse was generated that up-‐regulates Cldn6 in the distal lung. Pups had unlimited access to dox from conception until sacrifice date at embryonic day (E) 18.5. Quantitative PCR, immunoblotting, and immunohistochemistry revealed significantly elevated Cldn6 expression in transgenic mice compared to non-‐transgenic controls. There were no differences in terms of lung size, lung weight, or whole body weight at the time of necropsy. Histological evaluations led to the discovery that E18.5 Cldn6 transgenic pups appeared to be in the early canalicular stage of development coincident with fewer, thickened respiratory airspaces. In contrast, controls appeared to have entered the saccular stage characterized by thin airspace walls and spherical architecture. Immunostaining for transcriptional regulators including TTF‐1 and FoxA2 was conducted to assess cell differentiation and specific cell types were identified via staining for pro‐surfactant protein C (alveolar type II epithelial cells) or Clara Cell Secretory Protein (cub or Clara cells). Lastly, cell turnover was qualitatively measured via staining for cell proliferation or apoptosis. These data suggest that Cldn6 is an important junctional protein potentially involved in the programming of epithelial cells during lung development. Furthermore, genetic down‐regulation of Cldn6 as development proceeds may influence differentiation observed in the transition from the canalicular to the saccular lung.
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Papers by Samuel Belgique
Claudins are transmembrane proteins expressed in tight junctions that prevent paracellular transport of extracellular fluid and a variety of other substances. However, the expression profile of Claudin-6 (Cldn6) in the developing lung has not been characterized.
Methods and results
Cldn6 expression was determined during important periods of lung organogenesis by microarray analysis, qPCR and immunofluorescence. Expression patterns were confirmed to peak at E12.5 and diminish as lung development progressed. Immunofluorescence revealed that Cldn6 was detected in cells that also express TTF-1 and FoxA2, two critical transcriptional regulators of pulmonary branching morphogenesis. Cldn6 was also observed in cells that express Sox2 and Sox9, factors that influence cell differentiation in the proximal and distal lung, respectively. In order to assess transcriptional control of Cldn6, 0.5, 1.0, and 2.0-kb of the proximal murine Cldn6 promoter was ligated into a luciferase reporter and co-transfected with expression vectors for TTF-1 or two of its important transcriptional co-regulators, FoxA2 and Gata-6. In almost every instance, TTF-1, FoxA2, and Gata-6 activated gene transcription in cell lines characteristic of proximal airway epithelium (Beas2B) and distal alveolar epithelium (A-549).
Conclusions
These data revealed for the first time that Cldn6 might be an important tight junctional component expressed by pulmonary epithelium during lung organogenesis. Furthermore, Cldn6-mediated aspects of cell differentiation may describe mechanisms of lung perturbation coincident with impaired cell junctions and abnormal membrane permeability.
Claudins are transmembrane proteins expressed in tight junctions that prevent paracellular transport of extracellular fluid and a variety of other substances. However, the expression profile of Claudin-6 (Cldn6) in the developing lung has not been characterized.
Methods and results
Cldn6 expression was determined during important periods of lung organogenesis by microarray analysis, qPCR and immunofluorescence. Expression patterns were confirmed to peak at E12.5 and diminish as lung development progressed. Immunofluorescence revealed that Cldn6 was detected in cells that also express TTF-1 and FoxA2, two critical transcriptional regulators of pulmonary branching morphogenesis. Cldn6 was also observed in cells that express Sox2 and Sox9, factors that influence cell differentiation in the proximal and distal lung, respectively. In order to assess transcriptional control of Cldn6, 0.5, 1.0, and 2.0-kb of the proximal murine Cldn6 promoter was ligated into a luciferase reporter and co-transfected with expression vectors for TTF-1 or two of its important transcriptional co-regulators, FoxA2 and Gata-6. In almost every instance, TTF-1, FoxA2, and Gata-6 activated gene transcription in cell lines characteristic of proximal airway epithelium (Beas2B) and distal alveolar epithelium (A-549).
Conclusions
These data revealed for the first time that Cldn6 might be an important tight junctional component expressed by pulmonary epithelium during lung organogenesis. Furthermore, Cldn6-mediated aspects of cell differentiation may describe mechanisms of lung perturbation coincident with impaired cell junctions and abnormal membrane permeability.