Dataset Information

Dual stimulation by autoantigen and CpG fosters the proliferation of exhausted rheumatoid factor-specific CD21^low B cells in hepatitis C virus-cured mixed cryoglobulinemia.

ABSTRACT:

Introduction

Hepatitis C virus (HCV) causes mixed cryoglobulinemia (MC) by driving clonal expansion of B cells expressing B cell receptors (BCRs), often encoded by the VH1-69 variable gene, endowed with both rheumatoid factor (RF) and anti-HCV specificity. These cells display an atypical CD21low phenotype and functional exhaustion evidenced by unresponsiveness to BCR and Toll-like receptor 9 (TLR9) stimuli. Although antiviral therapy is effective on MC vasculitis, pathogenic B cell clones persist long thereafter and can cause virus-independent disease relapses.

Methods

Clonal B cells from patients with HCV-associated type 2 MC or healthy donors were stimulated with CpG or heath-aggregated IgG (as surrogate immune complexes) alone or in combination; proliferation and differentiation were then evaluated by flow cytometry. Phosphorylation of AKT and of the p65 NF-kB subunit were measured by flow cytometry. TLR9 was quantified by qPCR and by intracellular flow cytometry, and MyD88 isoforms were analyzed using RT-PCR.

Discussion

We found that dual triggering with autoantigen and CpG restored the capacity of exhausted VH1-69pos B cells to proliferate. The signaling mechanism for this BCR/TLR9 crosstalk remains elusive, since TLR9 mRNA and protein as well as MyD88 mRNA were normally expressed and CpG-induced phosphorylation of p65 NF-kB was intact in MC clonal B cells, whereas BCR-induced p65 NF-kB phosphorylation was impaired and PI3K/Akt signaling was intact. Our findings indicate that autoantigen and CpG of microbial or cellular origin may unite to foster persistence of pathogenic RF B cells in HCV-cured MC patients. BCR/TLR9 crosstalk might represent a more general mechanism enhancing systemic autoimmunity by the rescue of exhausted autoreactive CD21low B cells.

SUBMITTER: Del Padre M

PROVIDER: S-EPMC9945227 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Publications

Dual stimulation by autoantigen and CpG fosters the proliferation of exhausted rheumatoid factor-specific CD21<sup>low</sup> B cells in hepatitis C virus-cured mixed cryoglobulinemia.

Del Padre Martina M Marrapodi Ramona R Minafò Ylenia A YA Piano Mortari Eva E Radicchio Giovanna G Bocci Chiara C Gragnani Laura L Camponeschi Alessandro A Colantuono Stefania S Stefanini Lucia L Basili Stefania S Carsetti Rita R Fiorilli Massimo M Casato Milvia M Visentini Marcella M

Frontiers in immunology 20230208

<h4>Introduction</h4>Hepatitis C virus (HCV) causes mixed cryoglobulinemia (MC) by driving clonal expansion of B cells expressing B cell receptors (BCRs), often encoded by the VH1-69 variable gene, endowed with both rheumatoid factor (RF) and anti-HCV specificity. These cells display an atypical CD21low phenotype and functional exhaustion evidenced by unresponsiveness to BCR and Toll-like receptor 9 (TLR9) stimuli. Although antiviral therapy is effective on MC vasculitis, pathogenic B cell clone ...[more]

PMID: 36845129

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Project description:BackgroundThe genetic risk associated with rheumatoid arthritis (RA) includes genes regulating DNA methylation, one of the hallmarks of epigenetic re-programing, as well as many T-cell genes, with a strong MHC association, pointing to immunogenetic mechanisms as disease triggers leading to chronicity. The aim of our study was to explore DNA methylation in early, drug-naïve RA patients, towards a better understanding of early events in pathogenesis.ResultMonocytes, naïve and memory CD4+ T-cells were sorted from 6 healthy controls and 10 RA patients. DNA methylation was assessed using a genome-wide Illumina 450K CpG promoter array. Differential methylation was confirmed using bisulfite sequencing for a specific gene promoter, ELISA for several cytokines and flow cytometry for cell surface markers. Differentially methylated (DM) CpGs were observed in 1047 genes in naïve CD4+ T-cells, 913 in memory cells and was minimal in monocytes with only 177 genes. Naive CD4+ T-cells were further investigated as presenting differential methylation in the promoter of > 500 genes associated with several disease-relevant pathways, including many cytokines and their receptors. We confirmed hypomethylation of a region of the TNF-alpha gene in early RA and differential expression of 3 cytokines (IL21, IL34 and RANKL). Using a bioinformatics package (DMRcate) and an in-house analysis based on differences in β values, we established lists of DM genes between health and RA. Publicly available gene expression data were interrogated to confirm differential expression of over 70 DM genes. The lists of DM genes were further investigated based on a functional relationship database analysis, which pointed to an IL6/JAK1/STAT3 node, related to TNF-signalling and engagement in Th17 cell differentiation amongst many pathways. Five DM genes for cell surface markers (CD4, IL6R, IL2RA/CD25, CD62L, CXCR4) were investigated towards identifying subpopulations of CD4+ T-cells undergoing these modifications and pointed to a subset of naïve T-cells, with high levels of CD4, IL2R, and CXCR4, but reduction and loss of IL6R and CD62L, respectively.ConclusionOur data provided novel conceptual advances in the understanding of early RA pathogenesis, with implications for early treatment and prevention.

Dataset Information

Dual stimulation by autoantigen and CpG fosters the proliferation of exhausted rheumatoid factor-specific CD21^low B cells in hepatitis C virus-cured mixed cryoglobulinemia.

Introduction

Methods

Discussion

Publications

Dual stimulation by autoantigen and CpG fosters the proliferation of exhausted rheumatoid factor-specific CD21<sup>low</sup> B cells in hepatitis C virus-cured mixed cryoglobulinemia.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Dual stimulation by autoantigen and CpG fosters the proliferation of exhausted rheumatoid factor-specific CD21low B cells in hepatitis C virus-cured mixed cryoglobulinemia.

Introduction

Methods

Discussion

Publications

Dual stimulation by autoantigen and CpG fosters the proliferation of exhausted rheumatoid factor-specific CD21<sup>low</sup> B cells in hepatitis C virus-cured mixed cryoglobulinemia.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dual stimulation by autoantigen and CpG fosters the proliferation of exhausted rheumatoid factor-specific CD21^low B cells in hepatitis C virus-cured mixed cryoglobulinemia.