ABSTRACT
Increasing number of severe COVID 19 patients develop pulmonary Fibrosis, but the management of this complication is still unclear due to a lack of clinical trials. Aim of this study was to characterize mesenchymal cells (MC) isolated from 10 broncho-alveolar lavage (BAL, at 2 months after discharge) from patients with COVID19 fibrosis (COVID19-f) and to compare them with those isolated from 8 patients with collagen tissue diseaseassociated interstitial fibrosis(CTD-ILD). BAL fluid (BALf) levels of TGFbeta, VEGF, TIMP2, RANTES, IL6, IL8, and PAI1 were assessed by ELISA. Primary MC foci were cultured and expanded in D-MEM +10% FBS, characterized by flow cytometry and osteogenic and adipogenic differentiation. Collagen 1 production (+/-TGF-beta) was tested by WB and mRNA expression. BALf cytokine and GF levels were comparable in the two groups. Efficiency of MC isolation from BAL was 100% in COVID-f compared to 65% in CTD-ILD. MC antigen surface expression of CD105, CD73, CD90 (>90%, respectively), CD45, CD34, CD19 and HLA-DR (<5%, respectively) was comparable. None of MC samples differentiated in adipocytes, while COVID19-f were positive for calcium deposition. COVID19-f MC showed at WB, higher Collagen 1 production with respect to CTD-ILD with TGF-beta stimulation. Our preliminary data suggest MC from COVID19-f share several features with CTD-ILD but might have a higher response to fibrogenic and differentiation signals.
ABSTRACT
Background: Systemic and pulmonary uncontrolled activation of pro-inflammatory pathways following severe acute respiratory syndrome coronavirus 2 (Sars-Cov-2) infection can lead to development of serious short- and long-term complications such as ARDS and lung fibrosis. Mounting evidence reveals a positive correlation between cytokine overexpression in bronchoalveolar lavage fluid (BALF) and the severity of respiratory involvement in Sars-Cov-2 patients. We aimed to compare levels of metalloprotease 9 (MMP9) and fibrogenic Growth factors (VEGF, a-CTGF, FGF, PDGF) in BALF of intermediate medicine ward (IMW) Sars-Cov-2 and Intensive Care Unit (ICU) mechanically ventilated patients. Method(s): Sars-Cov-2 infection was diagnosed by Reverse transcriptase-polymerase chain reaction (RT-PCR) on respiratory samples. 10 IMW and 10 ICU patients were enrolled. ELISA assay was used to quantify growth factors and MMP9 on UV rays inactivated BAL fluid samples. Result(s): BALFs collected from ICU patients showed higher levels of Connective Tissue Growth Factor (CTGF;p<0.05) and MMP-9 (p<0,05) whereas inward patients with moderate pneumonia displayed higher titles of Vascular Endothelial Growth Factor (VEGF;p<0,05). FGF values were below detection limit in 90% of samples. No statistical difference in Platelet Derived Growth Factor (PDGF) levels were found between the two groups. Conclusion(s): Analogously to what observed for pro-inflammatory cytokines, early alveolar expression of MMP9 and CTGF are associated to a more severe outcome and might play a role in determining fibrotic evolution while VEGF does not seem to play a major role.