Clinical phenotypes of adult-onset Behçet's syndrome: a comprehensive cross-sectional study in China.

Behçet's syndrome (BS) is a variant vasculitis that can involve multiple organs with inflammatory manifestations. This study aimed to provide a more comprehensive analysis of the clinical phenotypes and characteristics of BS patients. We enrolled 2792 BS patients referred from China nationwide to Huadong Hospital Affiliated to Fudan University from October 2012 to December 2022. Detailed assessments of demographic information, clinical manifestations, laboratory results, gastroscopy, and medical imaging were conducted. Cluster analysis was performed based on 13 variables to determine the clinical phenotypes, and each phenotype was characterized according to the features of BS patients. A total of 1834 BS patients were included, while 958 invalid patients were excluded. The median age at onset was 31 years (IQR, 24-40 years), and the median disease duration was 10 years (IQR, 5-15 years). Eight clusters were identified, including mucocutaneous (n = 655, 35.7%), gastrointestinal (n = 363, 19.8%), articular (n = 184, 10%), ocular (n = 223, 12.2%), cardiovascular (n = 119, 6.5%), neurological (n = 118, 6.4%), vascular (n = 114, 6.2%), and hematological phenotype (n = 58, 3.2%). Ocular (RR = 1.672 (95% CI, 1.327-2.106); P < 0.001), gastrointestinal (RR = = 1.194 (95% CI, 1.031-1.383); P = 0.018), cardiovascular (RR = = 2.582 (95% CI, 1.842-3.620); P < 0.001), and vascular (RR = = 2.288 (95% CI, 1.600-3.272); P < 0.001) involvement were more prevalent in male BS patients, while the hematological (RR = 0.528 (95% CI, 0.360-0.776); P = 0.001) involvement was more common among female patients. BS presents significant heterogeneity and gender differences. The eight phenotypes of BS patients we propose hold the potential to assist clinicians in devising more personalized treatment and follow-up strategies. Key Points • This cluster analysis divided adult-onset BS into eight clinical phenotypes. • BS demonstrates a high level of clinical heterogeneity and gender differences. • Hematologic phenotypes of BS present distinctive clinical characteristics.

PLK1-activating IFI16-STING-TBK1 pathway induces apoptosis of intestinal epithelial cells in patients with intestinal Behçet's syndrome.

Inflammatory signals from immunological cells may cause damage to intestinal epithelial cells (IECs), resulting in intestinal inflammation and tissue impairment. Interferon-γ-inducible protein 16 (IFI16) was reported to be involved in the pathogenesis of Behçet's syndrome (BS). This study aimed to investigate how inflammatory cytokines released by immunological cells and IFI16 participate in the pathogenesis of intestinal BS. RNA sequencing and real-time quantitative PCR (qPCR) showed that the positive regulation of tumor necrosis factor-α (TNF-α) production in peripheral blood mononuclear cells (PBMCs) of intestinal BS patients may be related to the upregulation of polo like kinase 1 (PLK1) in PBMCs (P = 0.012). The plasma TNF-α protein level in intestinal BS was significantly higher than in healthy controls (HCs; P = 0.009). PBMCs of intestinal BS patients and HCs were co-cultured with human normal IECs (NCM460) to explore the interaction between immunological cells and IECs. Using IFI16 knockdown, PBMC-NCM460 co-culture, TNF-α neutralizing monoclonal antibody (mAb), stimulator of interferon genes (STING) agonist 2'3'-cGAMP, and the PLK1 inhibitor SBE 13 HCL, we found that PLK1 promotes the secretion of TNF-α from PBMCs of intestinal BS patients, which causes overexpression of IFI16 and induces apoptosis of IECs via the STING-TBK1 pathway. The expressions of IFI16, TNF-α, cleaved caspase 3, phosphorylated STING (pSTING) and phosphorylated tank binding kinase 1 (pTBK1) in the intestinal ulcer tissue of BS patients were significantly higher than that of HCs (all P < 0.05). PLK1 in PBMCs of intestinal BS patients increased TNF-α secretion, inducing IEC apoptosis via activation of the IFI16-STING-TBK1 pathway. PLK1 and the IFI16-STING-TBK1 pathway may be new therapeutic targets for intestinal BS.

Iguratimod inhibits osteoclastogenesis by modulating the RANKL and TNF-α signaling pathways.

BACKGROUND: Iguratimod, a small molecular drug, has been proven to have effective bone protection for treatment of patients with bone loss-related diseases, such as rheumatoid arthritis (RA). However, the exact bone protective mechanism of iguratimod remains to be determined. The purpose of this study was to better explore the underlying mechanism of bone protection of iguratimod. METHODS: Bone marrow monocytes from C57/BL6 mice were stimulated with either RANKL or TNF-α plus M-CSF. The effects of iguratimod on morphology and function of osteoclasts were confirmed by TRAP staining and bone resorption assay, respectively. The expression of osteoclast related genes was detected by RT-PCR and the activation of signal pathway was detected by Western blotting. We used rodent models of osteoporosis (ovariectomy) and of arthritis (modified TNF-α-induced osteoclastogenesis) to evaluate the osteoprotective effect of iguratimod in vivo. RESULTS: Iguratimod potently inhibited osteoclast formation in a dose-dependent manner at the early stage of RANKL-induced osteoclastogenesis, whereas iguratimod had no effect on M-CSF-induced proliferation and RANK expression in bone marrow monocytes. Bone resorption was significantly reduced by both early and late addition of iguratimod. Administration of iguratimod prevented bone loss in ovariectomized mice. The blockage of osteoclastogenesis elicited by iguratimod results from abrogation of the p38、ERK and NF-κB pathways induced by RANKL. Importantly, Iguratimod also dampened TNF-α-induced osteoclastogenesis in vitro and attenuated osteoclasts generation in vivo through disrupting NF-κB late nuclear translocation without interfering with IκBα degradation. CONCLUSIONS: Iguratimod not only suppresses osteoclastogenesis by interfering with RANKL and TNF-α signals, but also inhibits the bone resorption of mature osteoclasts. These results provided promising evidence for the therapeutic application of iguratimod as a unique treatment option against RA and especially in prevention of bone loss.

Stattic inhibits RANKL-mediated osteoclastogenesis by suppressing activation of STAT3 and NF-κB pathways.

Tofacitinib, a small molecule JAK inhibitor, has been widely used to reduce inflammation and inhibit progression of bone destruction in rheumatoid arthritis. STAT3, a downstream signaling molecule of JAK, plays a key role in the activation of signaling in response to inflammatory cytokines. Thus, targeting STAT3 may be an inspiring strategy for treating osteoclast-related diseases such as rheumatoid arthritis. In this study, we first investigated the effects of Stattic, a STAT3 inhibitor, on receptor activator of NF-κB ligand (RANKL)-mediated osteoclastogenesis. Stattic inhibited osteoclast differentiation and bone resorption in RANKL-induced RAW264.7 cells in a dose-dependent manner. Stattic also suppressed RANKL-induced upregulation of osteoclast-related genes tartrate-resistant acid phosphatase, matrix metalloproteinase 9, cathepsin K, RANK, tumor necrosis factor receptor-associated factor 6, and osteoclast-associated receptor in RAW264.7 cells. Moreover, Stattic exhibited an inhibitory effect on cell proliferation and cell cycle progression at higher dosages. At the molecular level, Stattic inhibited RANKL-induced activation of STAT3 and NF-κB pathways, without significantly affecting MAPK signaling. In addition, Stattic inhibited RANKL-induced expression of osteoclast-related transcription factors c-Fos and NFATc1. Importantly, Stattic also prevented bone loss caused by ovariectomy. Together, our data confirm that Stattic restricts osteoclastogenesis and bone loss by disturbing RANKL-induced STAT3 and NF-κB signaling. Thus, Stattic represents a novel type of osteoclast inhibitor that could be useful for conditions such as osteoporosis and rheumatoid arthritis.