Hellstrom, C. | bioRxiv Science

bioRxiv2022

XIST ribonucleoproteins promote female sex-biased autoimmunity

Autoimmune diseases disproportionately affect females more than males. The XX sex chromosome complement is strongly associated with susceptibility to autoimmunity. Xist long noncoding RNA (lncRNA) is expressed only in females to randomly inactivate one of the two X chromosomes to achieve gene dosage compensation. Here, we show that the Xist ribonucleoprotein (RNP) complex, comprised of numerous autoantigenic components, is an important driver of sex-biased autoimmunity. Inducible transgenic expression of a non-silencing form of Xist in male mice introduced Xist RNP complexes and sufficed to produce autoantibodies. Male SJL/J mice expressing transgenic Xist developed more severe multiorgan pathology in pristane-induced model of lupus than wild-type males. Xist expression in males reprogrammed T and B cell population and chromatin states to more resemble wild type females. Human patients with autoimmune diseases displayed significant autoantibodies to multiple components of XIST RNP. Thus, a sex-specific lncRNA scaffolds ubiquitous RNP components to drive sex-biased immunity. HIGHLIGHTSO_LITransgenic mouse models inducibly express Xist in male animals. C_LIO_LIXist expression in males induce autoantibodies and autoimmune pathology. C_LIO_LIXist in males reprograms T and B cell populations to female-like patterns. C_LIO_LIAutoantibodies to Xist RNP characterize female-biased autoimmune diseases. C_LI

molecular biology↗

bioRxiv2022

Autoantigenic properties of the aminoacyl tRNA synthetase family in idiopathic inflammatory myopathies

ObjectivesAutoantibodies are thought to play a key role in the pathogenesis of idiopathic inflammatory myopathies (IIM). However, up to 40% of IIM patients, even those with clinical manifestations of anti-synthetase syndrome (ASSD), test seronegative to all known myositis-specific autoantibodies (MSAs). We hypothesized the existence of new potential autoantigens among human cytoplasmic aminoacyl tRNA synthetases (aaRS) in patients with IIM. MethodsPlasma samples and clinical data from 217 patients with, 50 patients with ASSD, 165 without, and two with unknown ASSD status were included retrospectively, as well as serum from 156 age/sex-matched population controls. Samples were screened using a multiplex bead array assay for presence of autoantibodies against a panel of 118 recombinant protein variants, representing 33 myositis-related proteins, including all 19 cytoplasmic aaRS. ResultsWe identified reactivity towards 16 aaRS in 72 of the 217 patients. Twelve patients displayed reactivity against nine novel aaRS. The novel autoantibody specificities were detected in four patients previously seronegative for MSAs and in eight with previously detected MSAs. We also confirmed reactivity to four of the most common aaRS (Jo1, PL12, PL7, and EJ (n=45)) and identified patients positive for anti-Zo, -KS, and -HA (n=10) that were not previously tested. A low frequency of anti-aaRS autoantibodies was detected in controls. ConclusionOur results suggest that most, if not all, cytoplasmic aaRS may become autoantigenic. Autoantibodies against new aaRS may be found in plasma of patients previously classified as seronegative with potential high clinical relevance.

immunology↗