Betsy J. Barnes, United States of America
Feinstein Institute for Medical Research Center for Autoimmune Musculoskeletal and Hematopoietic DiseasePresenter of 2 Presentations
INHIBITION OF IRF5 HYPER-ACTIVATION PROTECTS FROM LUPUS ONSET AND SEVERITY
Abstract
Background and Aims
The transcription factor interferon regulatory factor 5 (IRF5) is a central mediator of innate and adaptive immunity. Genetic variations within IRF5 associate with risk of systemic lupus erythematosus (SLE) and mice lacking Irf5 are protected from lupus onset and severity, but how IRF5 functions in the context of SLE disease progression remains unclear.
Methods
Buffy coats were prepared from fresh blood drawn from consented male and female healthy donors and SLE patients. SLE patients fulfilled at least four of the classification criteria for SLE as defined by the ACR. IRF5 activation was determined by imaging flow cytometry on an Amnis Imagestream X Mark II. In vivo studies were performed in NZB/W F1 and MRL/lpr models of murine lupus. IL6 and anti-dsDNA Ig levels were measure by ELISA. Proteinuria was measured by test strip and Bradford protein assay. Serum auto-antibodies were measured by ANA-HEp-2.
Results
In NZB/W F1 mice, we show that murine Irf5 is hyper-activated before clinical onset in a cell type-specific manner. In SLE patients, IRF5 hyper-activation correlated with SLEDAI and dsDNA titers. Treatment of NZB/W F1 and MRL/lpr mice with IRF5 inhibitor attenuated lupus pathology by reducing serum ANA and dsDNA titers, which alleviated kidney pathology and improved overall survival. In ex vivo human studies, inhibitor blocked SLE serum-induced IRF5 activation and reversed basal IRF5 hyper-activation in SLE immune cells.
Conclusions
Altogether, this study provides the first in vivo pre-clinical support for treating SLE patients with an IRF5 inhibitor.
IRF5 GENETIC RISK VARIANTS DRIVE MYELOID-SPECIFIC IRF5 HYPER-ACTIVATION AND PRE-SYMPTOMATIC SLE
Abstract
Background and Aims
Genetic variants within/near the interferon regulatory factor 5 (IRF5) locus associate with systemic lupus erythematosus (SLE) across ancestral groups. The major IRF5-SLE risk haplotype is common across populations, yet immune functions for the risk haplotype are undefined.
Methods
Healthy donors carrying the major IRF5-SLE risk haplotype in European Caucasians (rs2004640, rs10954213, rs10488631, and rs142738614 (CGGGG indel)) were identified from the Feinstein Genotype and Phenotype (GaP) Registry after genotyping on the Illumina Human Immunochip. Participants carried either the major IRF5 homozygous risk or non-risk haplotype and had no personal/family history of autoimmune/inflammatory diseases or cancer. Immuno-phenotypes were characterized by ELISA, flow cytometry, ex vivo co-culture and RNA-sequencing.
Results
Contrary to previous studies in B lymphoblastoid cell lines and SLE immune cells, IRF5 genetic variants had little effect on IRF5 protein levels in healthy donors. Instead, we detected basal IRF5 hyper-activation in the myeloid compartment of risk donors that drives an SLE immune-phenotype. Risk donors were ANA positive with anti-Ro and -MPO specificity, had increased circulating plasma cells and plasmacytoid dendritic cells, and enhanced spontaneous NETosis. The IRF5-SLE immune-phenotype was conserved over time and probed mechanistically by ex vivo co-culture, indicating that risk neutrophils are drivers of the global immune-phenotype. RNAseq of risk neutrophils revealed increased IRF5 transcript expression, IFN pathway enrichment and decreased expression of ROS pathway genes.
Conclusions
Altogether, data support that individuals carrying the IRF5-SLE risk haplotype are more susceptible to environmental/stochastic influences that trigger chronic immune activation, predisposing to the development of autoimmune diseases, such as SLE.