A study on the morbid histopathological changes in COVID-19 patients with or without comorbidities using minimally invasive tissue sampling.

COVID-19 causes morbid pathological changes in different organs including lungs, kidneys, liver, and so on, especially in those who succumb. Though clinical outcomes in those with comorbidities are known to be different from those without-not much is known about the differences at the histopathological level. To compare the morbid histopathological changes in COVID-19 patients between those who were immunocompromised (Gr 1), had a malignancy (Gr 2), or had cardiometabolic conditions (hypertension, diabetes, or coronary artery disease) (Gr 3), postmortem tissue sampling (minimally invasive tissue sampling [MITS]) was done from the lungs, kidney, heart, and liver using a biopsy gun within 2 hours of death. Routine (hematoxylin and eosin) and special staining (acid fast bacilli, silver methanamine, periodic acid schiff) was done besides immunohistochemistry. A total of 100 patients underwent MITS and data of 92 patients were included (immunocompromised: 27, malignancy: 18, cardiometabolic conditions: 71). In lung histopathology, capillary congestion was more in those with malignancy, while others like diffuse alveolar damage, microthrombi, pneumocyte hyperplasia, and so on, were equally distributed. In liver histopathology, architectural distortion was significantly different in immunocompromised; while steatosis, portal inflammation, Kupffer cell hypertrophy, and confluent necrosis were equally distributed. There was a trend towards higher acute tubular injury in those with cardiometabolic conditions as compared to the other groups. No significant histopathological difference in the heart was discerned. Certain histopathological features were markedly different in different groups (Gr 1, 2, and 3) of COVID-19 patients with fatal outcomes.

Non-coding RNA in idiopathic interstitial pneumonia and Covid-19 pulmonary fibrosis.

Pulmonary fibrosis is the key feature of majority of idiopathic interstitial pneumonias (IIPs) as well as many patients with post-COVID-19. The pathogenesis of pulmonary fibrosis is a complex molecular process that involves myriad of cells, proteins, genes, and regulatory elements. The non-coding RNA mainly miRNA, circRNA, and lncRNA are among the key regulators of many protein coding genes and pathways that are involved in pulmonary fibrosis. Identification and molecular mechanisms, by which these non-coding RNA molecules work, are crucial to understand the molecular basis of the disease. Additionally, elucidation of molecular mechanism could also help in deciphering a potential diagnostic/prognostic marker as well as therapeutic targets for IIPs and post-COVID-19 pulmonary fibrosis. In this review, we have provided the latest findings and discussed the role of these regulatory elements in the pathogenesis of pulmonary fibrosis associated with Idiopathic Interstitial Pneumonia and Covid-19.

ACE2 protein expression in lung tissues of severe COVID-19 infection.

Angiotensin-converting enzyme 2 (ACE2) is a key host protein by which severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) enters and multiplies within cells. The level of ACE2 expression in the lung is hypothesised to correlate with an increased risk of severe infection and complications in COrona VIrus Disease 2019 (COVID-19). To test this hypothesis, we compared the protein expression status of ACE2 by immunohistochemistry (IHC) in post-mortem lung samples of patients who died of severe COVID-19 and lung samples obtained from non-COVID-19 patients for other indications. IHC for CD61 and CD163 was performed for the assessment of platelet-rich microthrombi and macrophages, respectively. IHC for SARS-CoV-2 viral antigen was also performed. In a total of 55, 44 COVID-19 post-mortem lung samples were tested for ACE2, 36 for CD163, and 26 for CD61, compared to 15 non-covid 19 control lung sections. Quantification of immunostaining, random sampling, and correlation analysis were used to substantiate the morphologic findings. Our results show that ACE2 protein expression was significantly higher in COVID-19 post-mortem lung tissues than in controls, regardless of sample size. Histomorphology in COVID-19 lungs showed diffuse alveolar damage (DAD), acute bronchopneumonia, and acute lung injury with SARS-CoV-2 viral protein detected in a subset of cases. ACE2 expression levels were positively correlated with increased expression levels of CD61 and CD163. In conclusion, our results show significantly higher ACE2 protein expression in severe COVID-19 disease, correlating with increased macrophage infiltration and microthrombi, suggesting a pathobiological role in disease severity.

Non-Coding RNA in Idiopathic Interstitial Pneumonia and Covid-19 Pulmonary Fibrosis (preprint)

Pulmonary fibrosis is the major manifestation of idiopathic interstitial pneumonia as well as post-COVID-19 complications. The pathogenesis of PF is a complex molecular process that involves many types of cells, proteins, genes, and regulatory elements. The non-coding RNA is the main regulatory element in this process which mainly includes;miRNA, circRNA, and lncRNA. These regulatory elements control the expression of many important genes and various pathways that are involved in the pathogenesis of pulmonary fibrosis. Identification and molecular mechanisms by which these non-coding RNA molecules works are very important because they do not only help to understand the molecular basis of the disease but could also serve as a potential diagnostic/prognostic marker as well as therapeutic targets. In this review, we have provided the latest findings and discussed the role of these regulatory elements in various biological processes and pathways involved in the pathogenesis of pulmonary fibrosis associated with IIPs and Covid-19.

Clinico-pathological features in fatal COVID-19 infection: a preliminary experience of a tertiary care center in North India using postmortem minimally invasive tissue sampling.

OBJECTIVES: To study the histopathology of patients dying of COVID-19 using post-mortem minimally invasive sampling techniques. METHODS: This was a single-center observational study conducted at JPNATC, AIIMS. Thirty-seven patients who died of COVID-19 were enrolled. Post-mortem percutaneous biopsies were taken from lung, heart, liver, kidney and stained with hematoxylin and eosin. Immunohistochemistry was performed using CD61 and CD163. SARS-CoV-2 virus was detected using IHC with primary antibodies. RESULTS: The mean age was 48.7 years and 59.5% were males. Lung histopathology showed diffuse alveolar damage in 78% patients. Associated bronchopneumonia was seen in 37.5% and scattered microthrombi in 21% patients. Immunopositivity for SARS-CoV-2 was observed in Type II pneumocytes. Acute tubular injury with epithelial vacuolization was seen in 46% of renal biopsies. Seventy-one percent of liver biopsies showed Kupffer cell hyperplasia and 27.5% showed submassive hepatic necrosis. CONCLUSIONS: Predominant finding was diffuse alveolar damage with demonstration of SARS-CoV-2 protein in the acute phase. Microvascular thrombi were rarely identified in any organ. Substantial hepatocyte necrosis, Kupffer cell hypertrophy, microvesicular, and macrovesicular steatosis unrelated to microvascular thrombi suggested that liver might be a primary target of COVID-19.

COVID-19: An up-to-date review - from morphology to pathogenesis.

The entire world is under a devastating pandemic caused by COVID-19 with a high mortality rate. Knowledge of the viral structure, factors that help in its progression and spread, pathological findings, diagnostic methods and, treatment modalities helps in understanding the viral disease and also in treating the patients in a better way besides preventing the community spread of this deadly infection. The causative agent is a single- stranded RNA virus. The clinical spectrum varies in symptomatic and asymptomatic patients, who later become potential silent carriers, thus unknowingly spreading the virus. The virus constantly undergoes recombination, with reports of cross-species infections. Studies have indicated a strong immunological basis of COVID-19 infection. Not only does it weaken the immune system causing multi-organ involvement but also helps in its progression and spread to others.Multiple organs especially lungs, heart, kidney, gastrointestinal and hepatic system, brain and skin are affected varying in their severity. Similarly, persons with associated co-morbidities are likely to be affected more in terms of the number as well as in the severity. Real- time reverse transcription polymerase chain reaction confirms the presence of COVID-19 infection. Serological diagnosis helps in diagnosing an ongoing outbreak or retrospective infection. Furthermore, it also identifies individuals who have been infected or have recovered from the disease especially the asymptomatic. This helps in the development of an effective vaccine indicating the status of herd immunity in the community. Different treatment modalities are being tried and under trial. This review article thus highlights the global epidemiological status, characteristic of the virus, symptomatology of the patients, role of diagnostic tests available, organs affected including their morphological changes and the latest line of treatment of COVID-19.