Many drugs can induce liver injury; however, vaccine-induced liver injury is a rare phenomenon. SARS-CoV-2 messenger RNA (mRNA) vaccines are now widely administered, and clinical evidence of liver injury has been reported.

To characterize the histologic features of SARS-CoV-2 mRNA vaccine-associated liver injury.

Thirteen liver biopsies from 12 patients with elevated liver enzymes clinically favored to be secondary to SARS-CoV-2 mRNA vaccine were identified between 2021 and 2022. Demographics, clinical information, and histologic features of liver biopsies were reviewed.

All patients (median age, 58 years; M:F = 4:8) received at least 1 dose of SARS-CoV-2 mRNA vaccines (7 Pfizer and 5 Moderna). Four patients had a history of liver disease. Nine patients developed symptoms between 1 day and 2 months after receiving the vaccine dose. Viral serologies were negative. Drug-induced liver injury was thought to be less likely clinically in the 3 patients who had started new medications. Autoimmune antibodies were detected in 9 patients. Moderate to severe active hepatitis was the dominant histologic pattern of injury (9 of 13 biopsies; 69%). Resolving hepatitis, cholestatic hepatitic injury, and bile duct injury were identified in 1 biopsy each. All patients recovered spontaneously or with steroid therapy, except one patient who developed autoimmune hepatitis.

Moderate to severe active hepatitis is commonly observed in SARS-CoV-2 mRNA vaccine-associated liver injury, and female patients may be more susceptible to injury. Liver injury resolves spontaneously or with steroid treatment. In rare cases, these vaccines may trigger an underlying immune condition.

The immune response to SARS-CoV-2 has been implicated in the onset of multiple, seemingly unrelated, autoimmune diseases. The immune response to SARS-CoV-2 has also been implicated in the unmasking and/or production of multiple autoantibodies, even in the absence of clinical disease. Despite such data, it remains unclear whether antibodies targeting antiviral signaling proteins and mitochondrial antigens reflect bystander activation or alternatively contribute to de novo viral immune escape mechanisms. With these comments in mind, a variety of professional antibody presenting cells and including lung resident macrophages of COVID-19 infected patients are impacted and dependent on the uptake of antibody-opsonized virus by Fcγ receptors; yet infection is aborted via antibody-dependent effector mechanisms or pyroptosis, possibly leading to autoantibody production, and autoinflammatory manifestations, respectively. TRIM21/Ro52, a cytosolic E3-ubiquitin ligase with an Fc-gamma receptor domain, functions as an intracytoplasmic antibody receptor, directs immune complexes binding virions but also autoantigens to autophagy. During autophagy, Ig-virions-TRIM21/Ro52-autoantigens complexes bind directly to class II human leukocyte antigen in lysosomal compartment, leading to subsequent presentation on the cell surface. This process favors the development of a specific humoral immune response but has the potential to lead to loss of tolerance. Interestingly, TRIM21/Ro52 can also contribute to pyroptosis. We propose that TRIM21/Ro52 is well-placed at the crossroad between the inflammatory response and clinical autoimmunity.

In recent years, the novel coronavirus infectious disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has led to over 670 million infections and nearly 7 million deaths worldwide. The global pandemic of COVID-19 has precipitated a significant public health crisis. The prevalence of liver function abnormalities associated with SARS-CoV-2 is as high as 53% among healthy individuals or patients with autoimmune hepatitis (AIH) and shows a positive correlation with disease severity; moreover, specific adaptive immune responses can influence the trajectory and outcomes of COVID-19. For instance, SARS-CoV-2 may impact autoimmunity through mechanisms such as excessive stimulation of immune responses and molecular mimicry, particularly in genetically predisposed individuals. Currently, the overall mutational trend of SARS-CoV-2 indicates heightened infectivity and immune evasion capabilities. Consequently, vaccination remains crucial for universal protection against this disease. Nevertheless, alongside the widespread implementation of vaccination programs globally, an increasing number of cases have been documented where COVID-19 vaccination appears to trigger new-onset autoimmune hepatitis; yet definitive evidence is still pending elucidation regarding causality. In this review, we analyse the clinical-immunological characteristics, risks associated with severe disease progression, and prognosis for AIH patients infected with SARS-CoV-2; discuss the detrimental effects exerted by SARS-CoV-2 on hepatic function; summarise the mechanisms and attributes leading to new-onset AIH; as well as provide insights into how vaccination may interfere with autoimmunity processes. We continue to underscore the significance of vaccination while aiming to enhance awareness concerning potential risks associated with it-this could facilitate better management strategies for autoimmune diseases along with appropriate adjustments in vaccination protocols. Although the precise triggering mechanism linking COVID-19-related events to AIH remains unclear, existing evidence suggests that this relationship is far from coincidental.

Primary biliary cholangitis (PBC) is a cholestatic, autoimmune liver disease with the presence of characteristic autoantibodies. The aim of the work was to determine the level of antibodies directed against bacterial antigens: Chlamydia pneumoniae (anti-Cpn), Yersinia enterolitica (anti-Y.e), Helicobacter pylori (anti-Hp), Mycoplasma pneumoniae (anti- Mp.) and Escherichia coli (E.coli) in sera of PBC patients. We also performed in vitro studies on the impact of the bacterial peptides on the specific antigen-antibody binding.

We screened 92 Polish PBC patients and sera samples from healthy donors and pathological controls. Autoantibodies and anti-bacterial antibodies were determined by commercially available ELISA kits. Specific inhibition of antibody binding was also detected by the in house ELISA method.

Anti-Cpn, anti-Y. enterolitica, anti-Hp, anti-M. pneumoniae and anti-E. coli antibodies were significantly more common in the group of PBC patients than in the pathological and healthy control groups: 74%, 40%, 84%, 39% and 69% respectively. The mean level of anti-Cpn, anti- Y.e, anti-Hp and anti- M.p in the PBC group was significantly higher than those in the healthy group (p < 0.001). and in patients with other liver diseases. In sera of patients with the presence of positive anti-mitochondrial antibodies (AMA), specific for PBC, anti-bacterial antibodies have been found in 80% vs. 50% in sera with AMA negative. We observed inhibition of specific antigen-antibody binding by the bacterial peptide: EClpP (E. coli caseinolytic protease) and adenine glycosylase from E. coli caseinolytic protease P, ClpP Y.e from peptide of Y. enterolitica, Mp PDC from M. pneumonia peptide and adenine glycosylase of E. coli. Bacterial factors influence the specific binding of antibodies to pyruvate dehydrogenase (PDC-E2), gp210 and KLHL12 (kelch-like peptide 12) antigens.

Microbial mimics may be the major targets of cross-reactivity with human pyruvate dehydrogenase, gp210, and KLHL12 in PBC.

Recently, medical interest has been growing in SARS-CoV-2 infection and its multiorgan involvement, including the liver. Up until now, a few reports have described autoimmune hepatitis (AIH) triggered by SARS-CoV-2 infection, but no data are available about the specific liver inflammatory infiltrate and cluster of differentiation. We report a case of AIH triggered by SARS-CoV-2 infection, with a particular focus on its histological and mainly immunohistochemical features.

A 60-year-old man, with a history of paucisymptomatic SARS-CoV-2 infection that occurred one month earlier, was admitted for alterations of hepatocellular necrosis and cholestasis indexes. He completed vaccination for SARS-CoV-2 a year earlier. The serologies for hepatotropic viruses were negative. The anti- smooth muscle antibodies (ASMA) and antinuclear antibodies (ANA) results were positive. Anti-liver kidney microsome (anti-LKM) antibodies and antimitochondrial (AMA) were negative. By liver biopsy, haematoxylin-eosin staining highlighted severe portal inflammation with a rich CD38+ plasma cell component, while immunohistochemical staining showed low cell CD4+ count and prevalence of CD8+ and CD3+. After biopsy, the patient started an immunosuppressant regimen, with benefit.

We can conclude that the patient developed a type 1 AIH triggered by SARS-CoV-2 infection. The presence of CD8 T-cells at immunohistochemical examination suggests different mechanisms from classic AIH. Similar cases are described after AIH triggered by SARS-CoV-2 vaccination.

The AIH after SARS-CoV-2 infection developed by the patient showed a histological picture similar to a classic AIH for the abundant presence of plasma cells, and immunohistochemical features similar to those described after SARS-CoV-2-vaccination.

Recently, medical interest has been growing in SARS-CoV-2 infection and its multiorgan involvement, including the liver. Underlying mechanisms are not still clear, more likely consisting of an inflammatory and immune mediated process rather than a direct cytopathic damage.Our report describes a rare case of type 1 AIH triggered by SARS-CoV-2 infection, showing a peculiar histological pattern, different from classic AIH, conversely similar to AIH triggered by SARS-CoV-2 vaccination.The mechanisms underlying liver involvement in SARS-CoV-2 infection are still under investigation. Further studies should be encouraged to improve understanding on this focus and to support physicians in its management.

There is an increasing number of liver injury cases resembling autoimmune hepatitis (AIH) following SARS-CoV-2 vaccination; however, an association has not yet been established.

A literature review was performed to identify articles regarding the association of AIH with vaccination, emphasizing on SARS-CoV-2 vaccines, and the proposed mechanisms. We then performed a literature search for AIH-like cases following SARS-CoV-2 vaccination, and we evaluated the included cases for AIH diagnosis using simplified diagnostic criteria (SDC), and for vaccination causality using the Naranjo score for adverse drug reactions.

We identified 51 AIH-like cases following SARS-CoV-2 vaccination. Forty cases (80%) were characterized as "probable", "at least probable", or "definite" for AIH diagnosis according to SDC. Forty cases (78.4%) were characterized as "probable", four (7.8%) as "possible", and three (5.8%) as "definite" for vaccine-related AIH according to the Naranjo score.

SARS-CoV-2 vaccine-related AIH carries several phenotypes and, although most cases resolve, immunosuppressive therapy seems to be necessary. Early diagnosis is mandatory and should be considered in any patient with acute or chronic hepatitis after SARS-CoV-2 vaccination, especially in those with pre-existing liver disease.

Liver diseases post-COVID-19 vaccination is extremely rare but can occur. A growing body of evidence has indicated that portal vein thrombosis, autoimmune hepatitis, raised liver enzymes and liver injuries, etc., may be potential consequence of COVID-19 vaccines.

To describe the results of a systematic review for new-onset and relapsed liver disease following COVID-19 vaccination.

For this systematic review, we searched Proquest, Medline, Embase, PubMed, CINAHL, Wiley online library, Scopus and Nature through the Preferred Reporting Items for Systematic Reviews and Meta Analyses PRISMA guideline for studies on the incidence of new onset or relapsed liver diseases post-COVID-19 vaccination, published from December 1, 2020 to July 31, 2022, with English language restriction.

Two hundred seventy-five cases from one hundred and eighteen articles were included in the qualitative synthesis of this systematic review. Autoimmune hepatitis (138 cases) was the most frequent pathology observed post-COVID-19 vaccination, followed by portal vein thrombosis (52 cases), raised liver enzymes (26 cases) and liver injury (21 cases). Other cases include splanchnic vein thrombosis, acute cellular rejection of the liver, jaundice, hepatomegaly, acute hepatic failure and hepatic porphyria. Mortality was reported in any of the included cases for acute hepatic failure (n = 4, 50%), portal vein thrombosis (n = 25, 48.1%), splanchnic vein thrombosis (n = 6, 42.8%), jaundice (n = 1, 12.5%), raised liver enzymes (n = 2, 7.7%), and autoimmune hepatitis (n = 3, 2.2%). Most patients were easily treated without any serious complications, recovered and did not require long-term hepatic therapy.

Reported evidence of liver diseases post-COIVD-19 vaccination should not discourage vaccination against this worldwide pandemic. The number of reported cases is relatively very small in relation to the hundreds of millions of vaccinations that have occurred and the protective benefits offered by COVID-19 vaccination far outweigh the risks.