Histological and serological features of acute liver injury after SARS-CoV-2 vaccination

Background & Aims Liver injury with autoimmune features after vaccination against Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2) is increasingly reported. We investigated a large international cohort of patients with acute hepatitis arising after SARS-CoV-2 vaccination, focusing on histological and serological features. Approach & Results Patients without known pre-existing liver diseases and transaminase levels ≥5x the upper limit of normal within 3 months after any anti-SARS-CoV-2 vaccine and available liver biopsy are included. Fifty-nine patients were recruited;35 females;median age 54 years;they were exposed to various combinations of mRNA, vectorial, inactivated and protein-based vaccines. Liver histology showed predominantly lobular hepatitis in 45 (76%) cases, predominantly portal hepatitis in 10 (17%), and other patterns in four (7%);seven had fibrosis Ishak stage ≥3, associated with more severe interface hepatitis. Autoimmune serology, centrally tested in 31 cases, showed anti-antinuclear antibody in 23 (74%), anti-smooth muscle antibody in 19 (61%), anti-gastric parietal cells in 8 (26%), anti-liver kidney microsomal in 4 (13%), anti-mitochondrial antibody in 4 (13%). Ninety-one percent were treated with steroids, ± azathioprine. Serum transaminase levels improved in all cases, and were normal in 24/58 (41%) after three months, and in 30/46 (65%) after six months. One patient required liver transplantation. Re-exposure to SARS-CoV-2 vaccines of 15 patients resulted in three relapses. Conclusion Acute liver injury arising after SARS-CoV-2 vaccination is frequently associated with lobular hepatitis and positive autoantibodies. Whether there is a causal relationship between liver damage and SARS-CoV-2 vaccines remains to be established. A close follow-up is warranted to assess the long-term outcome of this condition. Lay summary Cases of liver injury after vaccination against Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2) have been published. We investigated a large international cohort of patients with acute hepatitis after SARS-CoV-2 vaccination, focusing on liver biopsy findings and autoantibodies: liver biopsy frequently shows inflammation of the lobule, which is typical of recent injury, and autoantibodies are frequently positive. Whether there is a causal relationship between liver damage and SARS-CoV-2 vaccines remains to be established. Close follow-up is warranted to assess the long-term outcome of this condition.

Clinical, radiological and pathological findings in patients with persistent lung disease following SARS-CoV-2 infection.

Some patients experience pulmonary sequelae after SARS-CoV-2 infection, ranging from self-limited abnormalities to major lung diseases. Morphological analysis of lung tissue may help our understanding of pathogenic mechanisms and help to provide consistent personalised management. The aim of this study was to ascertain morphological and immunomolecular features of lung tissue. Transbronchial lung cryobiopsy was carried out in patients with persistent symptoms and computed tomography suggestive of residual lung disease after recovery from SARS-CoV-2 infection. 164 patients were referred for suspected pulmonary sequelae after COVID-19; 10 patients with >5% parenchymal lung disease underwent lung biopsy. The histological pattern of lung disease was not homogeneous and three different case clusters could be identified, which was mirrored by their clinical and radiological features. Cluster 1 ("chronic fibrosing") was characterised by post-infection progression of pre-existing interstitial pneumonias. Cluster 2 ("acute/subacute injury") was characterised by different types and grades of lung injury, ranging from organising pneumonia and fibrosing nonspecific interstitial pneumonia to diffuse alveolar damage. Cluster 3 ("vascular changes") was characterised by diffuse vascular increase, dilatation and distortion (capillaries and venules) within otherwise normal parenchyma. Clusters 2 and 3 had immunophenotypical changes similar to those observed in early/mild COVID-19 pneumonias (abnormal expression of STAT3 in hyperplastic pneumocytes and PD-L1, IDO and STAT3 in endothelial cells). This is the first study correlating histological/immunohistochemical patterns with clinical and radiological pictures of patients with post-COVID lung disease. Different phenotypes with potentially different underlying pathogenic mechanisms have been identified.

The pathogenic role of epithelial and endothelial cells in early-phase COVID-19 pneumonia: victims and partners in crime.

Current understanding of the complex pathogenesis of COVID-19 interstitial pneumonia pathogenesis in the light of biopsies carried out in early/moderate phase and histology data obtained at postmortem analysis is discussed. In autopsies the most observed pattern is diffuse alveolar damage with alveolar-epithelial type-II cell hyperplasia, hyaline membranes, and frequent thromboembolic disease. However, these observations cannot explain some clinical, radiological and physiopathological features observed in SARS-CoV-2 interstitial pneumonia, including the occurrence of vascular enlargement on CT and preserved lung compliance in subjects even presenting with or developing respiratory failure. Histological investigation on early-phase pneumonia on perioperative samples and lung biopsies revealed peculiar morphological and morpho-phenotypical changes including hyper-expression of phosphorylated STAT3 and immune checkpoint molecules (PD-L1 and IDO) in alveolar-epithelial and endothelial cells. These features might explain in part these discrepancies.

Covid-19 Interstitial Pneumonia: Histological and Immunohistochemical Features on Cryobiopsies.

BACKGROUND: The pathogenetic steps leading to Covid-19 interstitial pneumonia remain to be clarified. Most postmortem studies to date reveal diffuse alveolar damage as the most relevant histologic pattern. Antemortem lung biopsy may however provide more precise data regarding the earlier stages of the disease, providing a basis for novel treatment approaches. OBJECTIVES: To ascertain the morphological and immunohistochemical features of lung samples obtained in patients with moderate Covid-19 pneumonia. METHODS: Transbronchial lung cryobiopsy was carried out in 12 Covid-19 patients within 20 days of symptom onset. RESULTS: Histopathologic changes included spots of patchy acute lung injury with alveolar type II cell hyperplasia, with no evidence of hyaline membranes. Strong nuclear expression of phosphorylated STAT3 was observed in >50% of AECII. Interalveolar capillaries showed enlarged lumen and were in part arranged in superposed rows. Pulmonary venules were characterized by luminal enlargement, thickened walls, and perivascular CD4+ T-cell infiltration. A strong nuclear expression of phosphorylated STAT3, associated with PD-L1 and IDO expression, was observed in endothelial cells of venules and interstitial capillaries. Alveolar spaces macrophages exhibited a peculiar phenotype (CD68, CD11c, CD14, CD205, CD206, CD123/IL3AR, and PD-L1). CONCLUSIONS: Morphologically distinct features were identified in early stages of Covid-19 pneumonia, with epithelial and endothelial cell abnormalities different from either classical interstitial lung diseases or diffuse alveolar damage. Alveolar type II cell hyperplasia was a prominent event in the majority of cases. Inflammatory cells expressed peculiar phenotypes. No evidence of hyaline membranes and endothelial changes characterized by IDO expression might in part explain the compliance and the characteristic pulmonary vasoplegia observed in less-advanced Covid-19 pneumonia.