Histone modifications underlie monocyte dysregulation in patients with systemic sclerosis, underlining the treatment potential of epigenetic targeting.

BACKGROUND AND OBJECTIVE: Systemic sclerosis (SSc) is a severe autoimmune disease, in which the pathogenesis is dependent on both genetic and epigenetic factors. Altered gene expression in SSc monocytes, particularly of interferon (IFN)-responsive genes, suggests their involvement in SSc development. We investigated the correlation between epigenetic histone marks and gene expression in SSc monocytes. METHODS: Chromatin immunoprecipitation followed by sequencing (ChIPseq) for histone marks H3K4me3 and H3K27ac was performed on monocytes of nine healthy controls and 14 patients with SSc. RNA sequencing was performed in parallel to identify aberrantly expressed genes and their correlation with the levels of H3K4me3 and H3K27ac located nearby their transcription start sites. ChIP-qPCR assays were used to verify the role of bromodomain proteins, H3K27ac and STATs on IFN-responsive gene expression. RESULTS: 1046 and 534 genomic loci showed aberrant H3K4me3 and H3K27ac marks, respectively, in SSc monocytes. The expression of 381 genes was directly and significantly proportional to the levels of such chromatin marks present near their transcription start site. Genes correlated to altered histone marks were enriched for immune, IFN and antiviral pathways and presented with recurrent binding sites for IRF and STAT transcription factors at their promoters. IFNα induced the binding of STAT1 and STAT2 at the promoter of two of these genes, while blocking acetylation readers using the bromodomain BET family inhibitor JQ1 suppressed their expression. CONCLUSION: SSc monocytes have altered chromatin marks correlating with their IFN signature. Enzymes modulating these reversible marks may provide interesting therapeutic targets to restore monocyte homeostasis to treat or even prevent SSc.

Value of multidisciplinary reassessment in attribution of neuropsychiatric events to systemic lupus erythematosus: prospective data from the Leiden NPSLE cohort.

Objective: To determine the contribution of reassessment in the attribution process of neuropsychiatric (NP) events to SLE or other aetiologies in a large, prospective and multidisciplinary assessed NPSLE cohort and to compare these results with other available attribution models for NP events occurring in SLE. Methods: Three hundred and four consecutive SLE patients presenting NP events were evaluated. All subjects underwent standardized multidisciplinary medical, neuropsychological, laboratory and radiological examination on the inclusion and reassessment dates. Diagnosis was always established by multidisciplinary consensus. The final diagnosis after reassessment also took into account disease course and response to treatment. These data were compared with currently available attribution models for NP events in SLE. Results: A total of 463 NP events were established. After reassessment, attribution to SLE was discordant in 64 (13.8%) NP events when compared with the first visit. We show that 14.5% of NP events previously attributed to SLE reclassified as non-NPSLE. In 86.4% of these patients immunosuppressive therapy was started after the first visit. When reassessment and available attribution models were compared, NPSLE cases overlapped considerably. Although specificity was high for all comparisons (0.81-0.95), an important variation in sensitivity (0.39-0.83) and agreement estimates (κ = 0.29-0.68) was observed. The Italian algorithm showed the highest sensitivity and specificity (>0.80) and moderate agreement (0.59-0.64). Conclusion: In clinical practice NP events presenting in SLE are too often attributed to an immune-mediated origin. Multidisciplinary reassessment avoids misclassification in NPSLE. Multidisciplinary reassessment is the reference standard in NP events presenting in SLE and cannot be replaced by available attribution models.