Figure 2. Elastin degradation in the lungs of the COVID-19 patients.
The quantitative measurement of elastin fibers length in μm. The elastin fibers present in the alveolar walls were measured using ImageJ analysis. (A) Among COVID-19 negative patients. Elastin fibers appear as bundles in the alveolar walls (red arrows). (B) In COVID-19 patients, fragmentation of elastin fibers was observed (open red arrow). (C) Lengths of elastin fibers in COVID-10 positive and COVID-19 negative patients. (D) Elastolysis (red arrowhead) in the perivascular regions of the COVID-19 patients compared to COVID-19 negative patients. To validate elastolysis observed in morphometric analyses, lung tissue lysates prepared from COVID-19 positive and COVID-19 negative patients were evaluated by western blot analysis. (E) The lung tissue lysates from COVID-19 negative (2-5 lanes) and COVID-positive (6-11 lanes), and soluble elastin (EL) (12) were probed with anti-elastin antibodies and the immunoblot shows a strong band at 70 kDa representing tropoelastin. Lung tissue lysates of COVID-19 patients show degradation of tropoelastin. (F) The densities of tropoelastin were normalized to the histone protein levels in the lung homogenates. The values of elastin fibers lengths were represented as means ± SD in lung sections from 8 COVID-19 patients and 6 non-COVID-19 patients (2C). Data was represented as mean ± SD from lung sections from 6 COVID-19 patients and 4 non-COVID-19 patients (2F). Scale bar=100 μm.