IgG:IgM Ratios of Liver Plasma Cells Reveal Similar Phenotypes of Primary Biliary Cholangitis With and Without Features of Autoimmune Hepatitis

Multi-omics approaches for drug-response characterization in primary biliary cholangitis and autoimmune hepatitis variant syndrome

BACKGROUND

Primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) variant syndrome (VS) exhibit a complex overlap of AIH features with PBC, leading to poorer prognoses than those with PBC or AIH alone. The biomarkers associated with drug response and potential molecular mechanisms in this syndrome have not been fully elucidated.

METHODS

Whole-transcriptome sequencing was employed to discern differentially expressed (DE) RNAs within good responders (GR) and poor responders (PR) among patients with PBC/AIH VS. Subsequent gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted for the identified DE RNAs. Plasma metabolomics was employed to delineate the metabolic profiles distinguishing PR and GR groups. The quantification of immune cell profiles and associated cytokines was achieved through flow cytometry and immunoassay technology. Uni- and multivariable logistic regression analyses were conducted to construct a predictive model for insufficient biochemical response. The performance of the model was assessed by computing the area under the receiver operating characteristic (AUC) curve, sensitivity, and specificity.

FINDINGS

The analysis identified 224 differentially expressed (DE) mRNAs, 189 DE long non-coding RNAs, 39 DE circular RNAs, and 63 DE microRNAs. Functional pathway analysis revealed enrichment in lipid metabolic pathways and immune response. Metabolomics disclosed dysregulated lipid metabolism and identified PC (18:2/18:2) and PC (16:0/20:3) as predictors. CD4+ T helper (Th) cells, including Th2 cells and regulatory T cells (Tregs), were upregulated in the GR group. Pro-inflammatory cytokines (IFN-γ, TNF-α, IL-9, and IL-17) were downregulated in the GR group, while anti-inflammatory cytokines (IL-10, IL-4, IL-5, and IL-22) were elevated. Regulatory networks were constructed, identifying CACNA1H and ACAA1 as target genes. A predictive model based on these indicators demonstrated an AUC of 0.986 in the primary cohort and an AUC of 0.940 in the validation cohort for predicting complete biochemical response.

CONCLUSION

A combined model integrating genomic, metabolic, and cytokinomic features demonstrated high accuracy in predicting insufficient biochemical response in patients with PBC/AIH VS. Early recognition of individuals at elevated risk for insufficient response allows for the prompt initiation of additional treatments.

Guidelines on the Diagnosis and Management of Primary Biliary Cholangitis (2021)

In 2015, the Chinese Society of Hepatology and the Chinese Society of Gastroenterology published a consensus on primary biliary cholangitis (PBC). In the past years, numerous clinical studies have been published in the field of PBC. To guide the clinical diagnosis and management of PBC patients, the Chinese Society of Hepatology invited a panel of experts to assess the new clinical evidence and formulate the current guidelines.

Inflammasome and pyroptosis in autoimmune liver diseases

Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and IgG4-related sclerosing cholangitis (IgG4-SC) are the four main forms of autoimmune liver diseases (AILDs), which are all defined by an aberrant immune system attack on the liver. Most previous studies have shown that apoptosis and necrosis are the two major modes of hepatocyte death in AILDs. Recent studies have reported that inflammasome-mediated pyroptosis is critical for the inflammatory response and severity of liver injury in AILDs. This review summarizes our present understanding of inflammasome activation and function, as well as the connections among inflammasomes, pyroptosis, and AILDs, thus highlighting the shared features across the four disease models and gaps in our knowledge. In addition, we summarize the correlation among NLRP3 inflammasome activation in the liver-gut axis, liver injury, and intestinal barrier disruption in PBC and PSC. We summarize the differences in microbial and metabolic characteristics between PSC and IgG4-SC, and highlight the uniqueness of IgG4-SC. We explore the different roles of NLRP3 in acute and chronic cholestatic liver injury, as well as the complex and controversial crosstalk between various types of cell death in AILDs. We also discuss the most up-to-date developments in inflammasome- and pyroptosis-targeted medicines for autoimmune liver disorders.

The Inconvenient Truth of Primary Biliary Cholangitis/Autoimmune Hepatitis Overlap Syndrome

The term 'PBC/AIH-overlap' has been applied when features of autoimmune hepatitis (AIH), be they biochemical, serological or histological, coexist with primary biliary cholangitis (PBC), either at first presentation or sequentially during disease course. Several treatment paradigms have been proposed, extrapolated from those of the primary conditions. However, there are no randomised studies showing improved survival with combination therapy compared to bile acid monotherapy. In the absence of high-quality evidence, multidisciplinary patient-specific approaches must be used to individualise treatment pathways, with appreciation that disease phenotypes are not always static, differ in treatment responses, and have the potential to evolve over time.

IgG and IgM Immunohistochemistry in Primary Biliary Cholangitis (PBC) and Autoimmune Hepatitis (AIH) Liver Explants

OBJECTIVES

Primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) can be difficult to distinguish in end-stage liver disease. Previous studies have shown that immunoglobulin G (IgG) and immunoglobulin M (IgM) immunostaining can differentiate AIH from PBC in needle core biopsy specimens, and we seek to extend these data to cirrhotic liver explants, in which the histology of AIH or PBC may be indiscernible.

METHODS

Clinical data were reviewed for 20 patients with PBC cirrhosis and 16 with AIH cirrhosis. Immunohistochemistry for IgM and IgG was performed on representative blocks of explanted livers. Three high-power fields with the highest concentration of IgG- and IgM-positive plasma cells were counted and compared.

RESULTS

The average number of IgM-positive plasma cells was significantly higher in PBC explants (7.3) than in AIH (1.8) (P = .001). There was no significant difference in the average number of IgG-positive plasma cells in PBC (2.5) and AIH (2.8) (P = .8). The IgG/IgM ratio was more likely to be less than 1.0 in PBC (17/20, 85%) compared with AIH (7/16, 44%) (P = .01).

CONCLUSIONS

Our study demonstrates that the absolute number of IgM plasma cells is greater in explants of cirrhotic PBC compared with AIH. These findings may be helpful in the evaluation of cryptogenic cirrhosis.

We Are Not Immune: Racial and Ethnic Disparities in Autoimmune Liver Diseases

Autoimmune liver diseases are attributed to a complex interplay of biologic, acquired, and environmental factors. Increased prevalence, later stage at presentation, worse response to standard therapy, and transplant-related disparities have all been reported in racial and ethnic minorities such as Black and Latinx patients with autoimmune liver diseases. While biology and inherited genetic predispositions may partly explain these disparities, definitive and universal genetic variations underlying these differences in outcomes have not been defined. Nonetheless, socioeconomic status, access to health care, environmental and societal factors, and implicit provider bias can all contribute to poor patient outcomes. There remains an unmet need to understand and mitigate the factors contributing to health inequity in autoimmune liver diseases. In this review, we summarize the data on racial and ethnic disparities in presentation, treatment response, and outcomes pertaining to autoimmune liver diseases in minority populations, on the premise that understanding disparities is the first step toward reaching health equity.

The utility of immunoglobulin A/complement 3 and immunoglobulin G/immunoglobulin M ratios in the assessment of disease activation in patients with Behçet disease

OBJECTIVE

Pathogenesis of Behçet disease (BD) has not yet been clearly revealed and there is no ideal test for the estimation of disease activation at present. This study aimed to assess the efficiencies of IgG/IgM and IgA/C3 ratios in determining activation of BD.

METHOD

This retrospective cohort study consisted of 140 patients with BD. Patients were divided into two groups: (1) active BD (n = 89) and (2) inactive BD (n = 51) and were compared in terms of  demographic features, clinical characteristics and laboratory test results. IgA/C3 and IgG/IgM ratios were compared according to organ system involvement; receiver operating characteristic (ROC) curve analysis was performed in order to assess the performance of IgA/C3 and IgG/IgM ratios in determining patient disease status.

RESULTS

Significantly higher levels of erythrocyte sedimentation rate, C-reactive protein, IgA, G, C4, IgA/C3, IgG/IgM ratios (p = .007 for IgA and p < .001 for others) and significantly lower levels of IgM and C3 were observed in patients with active BD (p < .001). The IgG/IgM ratio was significantly higher in patients with vascular involvement (p = .017) and the IgA/C3 ratio was significantly higher in patients with arthritis (p = .007). Cut-off values of 0.019 (70.8% sensitivity, 62% specificity) and 7.08 (84.3% sensitivity, 80% specificity) were determined for IgA/C3 and IgG/IgM ratios, respectively.

CONCLUSION

IgA/C3 and IgG/IgM ratios may be used as additional parameters for the assessment of BD status.