Global and regional epidemiology of psoriatic arthritis in patients with psoriasis: A comprehensive systematic analysis and modelling study.

OBJECTIVES: To provide a comprehensive analysis and modelling of the global epidemiology of psoriatic arthritis (PsA) in patients with psoriasis. METHODS: We reviewed and analysed PsA epidemiology studies over the past 45 years. A Bayesian hierarchical linear mixed model was developed to provide comprehensive age- and sex-specific epidemiologic estimates in different countries and regions. RESULTS: Three hundred and sixty-three studies were systematically reviewed. The incidence of PsA in patients with psoriasis varied from 2.31 per 1000 person-years in the United Kingdom to 74.00 per 1000 person-years in several Western European countries. The global prevalence of PsA in patients with psoriasis is estimated to be 17.58% (3.33%, 43.69%). Regionally, the overall prevalence of PsA in patients with psoriasis varies from 7.62% (4.18%, 12.28%) in Australasia to 26.59% (18.89%, 35.76%) in North America. The Caribbean and Central Latin America also have relatively high prevalence and are estimated at 23.14% (14.06%, 35.17%) and 22.81% (14.36%, 32.25%), respectively. The prevalence of PsA is higher in adults than children (23.93% vs 8.59%) and also slightly higher in females than males (19.14% vs 16.01%). CONCLUSIONS: This study provides valuable insights into the global epidemiology of PsA. It also serves as a useful resource for researchers in areas lacking relevant studies. These findings have important implications for clinicians managing the course of PsA and for health policymakers in resource allocation.

Cannabinoid receptor 2 selective agonist alleviates systemic sclerosis by inhibiting Th2 differentiation through JAK/SOCS3 signaling.

Systemic sclerosis (SSc) poses a significant challenge in autoimmunology, characterized by the development of debilitating fibrosis of skin and internal organs. The pivotal role of dysregulated T cells, notably the skewed polarization toward Th2 cells, has been implicated in the vascular damage and progressive fibrosis observed in SSc. In this study, we explored the underlying mechanisms by which cannabinoid receptor 2 (CB2) highly selective agonist HU-308 restores the imbalance of T cells to alleviate SSc. Using a bleomycin-induced SSc (BLM-SSc) mouse model, we demonstrated that HU-308 effectively attenuates skin and lung fibrosis by specifically activating CB2 on CD4+ T cells to inhibit the polarization of Th2 cells in BLM-SSc mice, which was validated by Cnr2-specific-deficient mice. Different from classical signaling downstream of G protein-coupled receptors (GPCRs), HU-308 facilitates the expression of SOCS3 protein and subsequently impedes the IL2/STAT5 signaling pathway during Th2 differentiation. The deficiency of SOCS3 partially mitigated the impact of HU-308. Analysis of a cohort comprising 80 SSc patients and 82 healthy controls revealed an abnormal elevation in the Th2/Th1 ratio in SSc patients. The proportion of Th2 cells showed a significant positive correlation with mRSS score and positivity of anti-Scl-70. Administration of HU-308 to PBMCs and peripheral CD4+ T cells from SSc patients led to the upregulation of SOCS3, which effectively suppressed the aberrantly activated STAT5 signaling pathway and the proportion of CD4+IL4+ T cells. In conclusion, our findings unveil a novel mechanism by which the CB2 agonist HU-308 ameliorates fibrosis in SSc by targeting and reducing Th2 responses. These insights provide a foundation for future therapeutic approaches in SSc by modulating Th2 responses.

Deubiquitination of aryl hydrocarbon receptor (AhR) by USP21 negatively regulates Th17 cells differentiation.

Aryl hydrocarbon receptor (AhR) is a key transcription factor that modulates the differentiation of T helper 17 (Th17) cells. How AhR is regulated at the post-translational level in Th17 cells remains largely unclear. Here we identify USP21 as a newly defined deubiquitinase of AhR. We demonstrate that USP21 interacts with and stabilizes AhR by removing the K48-linked polyubiquitin chains from AhR. Interestingly, USP21 inhibits the transcriptional activity of AhR in a deubiquitinating-dependent manner. USP21 deubiquitinates AhR at the K432 residue, and the maintenance of ubiquitination on this site is required for the intact transcriptional activity of AhR. Moreover, the deficiency of USP21 promotes the differentiation of Th17 cells both in vitro and in vivo. Consistently, adoptive transfer of USP21 deficient naïve CD4+ T cells elicits more severe colitis in Rag1-/- recipients. Therefore, our study reveals a novel mechanism in which USP21 deubiquitinates AhR and negatively regulates the differentiation of Th17 cells.