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Titre : | Marqueurs de limmunité muqueuse bronchique dans le syndrome de détresse respiratoire aigüe |
Auteurs : | Priscilla Matumikina Kalueta, Auteur ; Charles Pr Pilette, Promoteur |
Type de document : | Travail de fin d'études |
Editeur : | Woluwe-Saint-Lambert : Haute École Léonard de Vinci, 2022 |
Langues: | Français |
Index. décimale : | TFE - Biologie médicale |
Descripteurs : |
HE Vinci Allergie et immunologie ; Immunité muqueuse ; Immunoglobulines ; Syndrome de détresse respiratoire |
Mots-clés: | immunoglobuline A |
Résumé : |
Background ARDS is a complex syndrome which has long been considered as a purely alveolar disease. Therefore, bronchial involvement is poorly characterized to date. Moreover, the impact of the alteration of the immune functions of the respiratory mucosa in the course of ARDS and in the development of complications remains unclear. Hence, the main objective of this study was to evaluate the immunity of the bronchial mucosa in patients with ARDS secondary to Covid-19 or not, by characterizing the bronchial damage observed in these patients. A particular focus will be put on Immunoglobulin A (IgA), and its carrier protein which allows the transcytosis of IgA throughout epithelial cells, polymeric Immunoglobulin Receptor (pIgR). IgA and pIgR are one of the frontline protections of the lungs against pathogens. Methods For this purpose, Tyramide Signal Amplification (TSA) immunolabeling and ELISA assays were performed. TSA was performed on human tissue, ELISA on serum and BAL. Two cohorts of patients with ARDS (secondary to Covid-19 or not) were compared to a cohort of control patients. ELISA results were obtained using a Bio-Rad absorbance spectrophotometer. Graphs were made on PRISM software. TSA images were obtained with a ZEISS fluorescent scanner. Results TSA: Based on a qualitative visual estimation, fluorescent scan images suggest that the bronchial epithelium is affected. In particular, p63 (basal cell marker) appears to be less expressed in ARDS and ARDS-Covid patients. In addition, the expression of IgA appeared to be increased in ARDS-Covid patients. TSA images will be quantified by Visiopharm software. ELISA assays: there is a significant increase in serum concentration of Secretory Component (SC, the extracellular part of pIgR), S-IgA1, S-IgA2 between ARDS patients (Covid or not) and controls. As these proteins are not expected to be found in blood, it could reflect a spilling to the blood from the bronchial lumen through a degraded epithelium. In comparison, the same trend was found for S-RAGE (marker of type I pneumocyte damage) and CC16 (marker of Club Cells). Besides, no significant difference in serum total IgA1 and IgA2 concentration was found between ARDS patients (Covid or not) and controls. This confirms that the difference observed for S-IgA1 and S-IgA2 is indeed epithelial. Furthermore, serum levels of SC and S-IgA1 are significantly higher in non-Covid ARDS patients compared to Covid ARDS, despite a similar severity between the two groups, suggesting that the bronchial epithelial dysfunction might be less severe in ARDS related to Covid. Finally, there was a significant increase in SC, S-IgA1 and S-IgA2 (as well as total IgA1) in Covid patients between day 1 and day 7, no change was observed in non-Covid ARDS patients. Conclusions: S-IgAs and SC were significantly increased in the blood of patients with ARDS, related to Covid or not, the increase being significantly larger in the latter group. This suggests a dysfunction of bronchial epithelium and should be confirmed by quantitative analysis of immunostainings of lung tissue of the same groups of patients. |
Accès : | Identifiez-vous avant d'accéder au document électronique |
Disponible en ligne : | Oui |
Lieu du stage : | UCL-IREC-Pneumologie |
Département : | Biologie médicale |
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TFE - Biologie médicale Adobe Acrobat PDF |