Dysregulation of RasGRP1 in rheumatoid arthritis and modulation of RasGRP3 as a biomarker of TNFα inhibitors

Abstract

BackgroundB and T cells play a key role in rheumatoid arthritis (RA) pathophysiology. RasGRP1 and RasGRP3 are involved in T and B cell receptors signaling, and belong to gene combination able to predict infliximab responsiveness, leading to the question of RasGRP1 and RasGRP3 involvement in RA.MethodsRasGRP1 and RasGRP3 expression levels were measured by qRT-PCR and/or western-blot in peripheral blood mononuclear cells (PBMCs), in T and B cells from untreated RA patients and in RA patients treated by TNFα inhibitors. T and B cells from healthy controls (HC) were cultured with TNFα, and TNFα receptors neutralizing antibodies to highlight the TNFα effects on RasGRP1 and RasGRP3 pathways. MAPK pathways and apoptosis were respectively analyzed using the Proteome Profiler arrays and flow cytometry.ResultsIn PBMCs from RA patients, gene expression levels of RasGRP1 were invariant while RasGRP3 was downregulated under TNFα inhibitors and upregulated under TNFα. In T cells from RA patients, RasGRP1 was decreased and its gene expression level was correlated with disease activity. In T cells from HC, TNFα stimulation increased RasGRP1 gene expression level while it reduced RasGRP1 protein expression level. Bryostatin-1 experiments have confirmed that the TNFα effect observed on T cells proliferation was due to the decrease of RasGRP1 expression. Besides, RasGRP3 expression level increased in PBMCs from RA patients under TNFα and in B cells from HC leading us to conclude that RasGRP3 in B cells was modulated by TNFα.ConclusionThis study demonstrates RasGRP1 dysregulation in RA patients while RasGRP3 is characterized as a biomarker linked to TNFα inhibitors. After binding to TNFR1, TNFα reduced RasGRP1 protein expression resulting in inhibition of T cell activation.Trial registrationClinicaltrials.gov NCT00234234, registered 04 November 2008; NCT00767325, registered 05 October 2005.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0894-9) contains supplementary material, which is available to authorized users.

Mechanistic Characterization of RASGRP1 Variants Identifies an hnRNP-K-Regulated Transcriptional Enhancer Contributing to SLE Susceptibility

“…A recent study reported a heterozygous mutation in RASGRP1 correlated with autoimmune lymphoproliferative syndrome (ALPS)-like disease (17). RASGRP1 expression in T-cells also correlated negatively with rheumatoid arthritis disease activity (18). Dysregulated expression of RASGRP1 has been observed in human SLE.…”

A Histidine pH sensor regulates activation of the Ras-specific guanine nucleotide exchange factor RasGRP1

“…A polymorphism (Arg 519 Gly) in Rasgrp1 in mice results in T cell abnormalities and autoimmunity ( Daley et al, 2013 ). Furthermore, several genetics studies have linked single nucleotide polymorphisms (SNPs) in RasGRP1 to human autoimmune disease ( Plagnol et al, 2011 ; Qu et al, 2009 ), and low RasGRP1 levels have been detected in T lymphocytes from patients with Systemic Lupus Erythematosus (SLE) ( Yasuda et al, 2007 ), and rheumatoid arthritis (RA) ( Golinski et al, 2015 ). Complete RasGRP1 deficiency in a patient leads to a novel primary immunodeficiency, with impaired activation and proliferation of the patient's T- and B- cells and defective killing by cytotoxic T cells and NK cells ( Roose, 2016 ; Salzer et al, 2016 ).…”

Genome-wide scans for signatures of selection in Mangalarga Marchador horses using high-throughput SNP genotyping

“…Other genes, TNPO2 and WDR83, were related to tumor development. One region on ECA1 harbored the gene RASGRP1, which was found in common between ROH and iHS and plays a key role in the development of T and B cells [40]. Studies have associated RASGRP with disease phenotypes in bovine animals [41,42] and dogs [43].…”