Objective Erythropoietin (EPO) known as an erythrocyte-stimulating factor is increased in patients with rheumatoid arthritis (RA). Nevertheless, the function of EPO in the process of RA and relative mechanism needs to be further clarified. Methods The level of EPO in serum and synovial fluid from patients with RA and healthy controls was determined by . Collagen-induced arthritis (CIA) mice were constructed to confirm the role of EPO on RA pathogenesis. Differentially expressed genes (DEGs) of EPO-treated fibroblast-like synoviocyte (FLS) were screened by transcriptome sequencing. The transcription factor of neuraminidase 3 (NEU3) of DEGs was verified by double luciferase reporting experiment, DNA pulldown, electrophoretic mobility shift assay and chromatin immunoprecipitation-quantitative PCR (qPCR) assay. Results The overexpression of EPO was confirmed in patients with RA, which was positively associated with Disease Activity Score 28-joint count. Additionally, EPO intervention could significantly aggravate the joint destruction in CIA models. The upregulation of NEU3 was screened and verified by transcriptome sequencing and qPCR in EPO-treated FLS, and signal transducer and activator of transcription 5 was screened and verified to be the specific transcription factor of NEU3. EPO upregulates NEU3 expression via activating the Janus kinase 2 (JAK2)-STAT5 signalling pathway through its receptor EPOR, thereby to promote the desialylation through enhancing the migration and invasion ability of FLS, which is verified by JAK2 inhibitor and NEU3 inhibitor. Conclusion EPO, as a proinflammatory factor, accelerates the process of RA through transcriptional upregulation of the expression of NEU3 by JAK2/STAT5 pathway.

Rheumatoid arthritis (RA) is the most common chronic autoimmune disease worldwide. Although progress has been made in RA treatment in recent decades, remission cannot be effectively achieved for a considerable proportion of RA patients. Thus, novel potential targets for therapeutic strategies are needed. Semaphorin 5A (SEMA5A) plays a pivotal role in RA progression by facilitating pannus formation, and it is a promising therapeutic target. In this study, we sought to develop an antibody treatment strategy targeting SEMA5A and evaluate its therapeutic effect using a collagen-induced arthritis (CIA) model. We generated SYD12-12, a fully human SEMA5A blocking antibody, through phage display technology. SYD12-12 intervention effectively inhibited angiogenesis and aggressive phenotypes of RA synoviocytes in vitro and dose-dependently inhibited synovial hyperplasia, pannus formation, bone destruction in CIA mice. Notably, SYD12-12 also improved the Treg/Th17 imbalance in CIA mice. We confirmed through immunofluorescence and molecular docking that SYD12-12 integrated with the unique TSP-1 domain of SEMA5A. In conclusion, we developed and characterized a fully human SEMA5A-blocking antibody for the first time. SYD12-12 effectively alleviated disease progression in CIA mice by inhibiting pannus formation and improving the Treg/Th17 imbalance, demonstrating its potential for the RA treatment.

The 2A protease (2A ^pro ) encoded by enterovirus 71 (EV71) serves as an accessory protein with significant involvement in the regulation of EV71 infection and viral replication. EV71-2A ^pro exhibits the ability to suppress various host factors, thereby disrupting the cellular antiviral immune response. However, whether host factors downregulate EV71-2A ^pro remains largely unknown. Here, we discovered that the speckle-type POZ protein (SPOP), functioning as a host E3 ubiquitin ligase, triggers ubiquitination modifications and subsequent degradation of EV71-2A ^pro . SPOP interacts with EV71-2A ^pro and exhibits a dose-dependent downregulation of EV71-2A ^pro levels. Conversely, knockdown of endogenous SPOP upregulated EV71-2A ^pro levels. Subsequent investigations revealed that the SPOP facilitates the lysosome-dependent degradation of EV71-2A ^pro by inducing K48-linked polyubiquitination of EV71-2A ^pro , which ultimately restricts EV71 replication. These findings shed light on the ubiquitination and lysosome-dependent regulation of the crucial EV71-encoded protease, offering a potential therapeutic target for the treatment of EV71 infection. IMPORTANCE: EV71 poses a significant health threat to children aged 5 and below. The process of EV71 infection and replication is predominantly influenced by ubiquitination modifications. Our previous findings indicate that EV71 prompts the activation of host deubiquitinating enzymes, thereby impeding the host interferon signaling pathway as a means of evading the immune response. Nevertheless, the precise mechanisms by which the host employs ubiquitination modifications to hinder EV71 infection remain unclear. The present study demonstrated that the nonstructural protein 2A ^pro , which is encoded by EV71, exhibits ubiquitination and degradation mediated by the host E3 ubiquitin ligase SPOP. In addition, it is the first report, to our knowledge, that SPOP is involved in the host antiviral response.

Connective tissue growth factor (CTGF) has been recently acknowledged as an ideal biomarker in the early disease course, participating in the pathogenesis of pannus formation in rheumatoid arthritis (RA). However, existing approaches for the detection of or antagonist targeting CTGF are either lacking or unsatisfactory in the diagnosis and treatment of RA. To address this, we synthesized and screened high-affinity single-stranded DNA aptamers targeting CTGF through a protein-based SELEX procedure. The structurally optimized variant AptW2-1-39-PEG was characterized thoroughly for its high-affinity (KD 7.86 nM), sensitivity (minimum protein binding concentration, 2 ng), specificity (negative binding to other biomarkers of RA), and stability (viability-maintaining duration in human serum, 48 h) properties using various biochemical and biophysical assays. Importantly, we showed the antiproliferative and antiangiogenic activities of the aptamers obtained using functional experiments and further verified the therapeutic effect of the aptamers on joint injury and inflammatory response in collagen-induced arthritis (CIA) mice, thus advancing this study into actual therapeutic application. Furthermore, we revealed that the binding within AptW2-1-39-PEG/CTGF was mediated by the thrombospondin 1 (TSP1) domain of CTGF using robust bioinformatics tools together with immunofluorescence. In conclusion, our results revealed a novel aptamer that holds promise as an additive or alternative approach for CTGF-targeting diagnostics and therapeutics for RA.

Protein citrullination modification plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA), and anti-citrullinated protein antibodies (ACPAs) are extensively employed for clinical diagnosis of RA. However, there remains limited understanding regarding specific citrullinated proteins and their implications in the progression of RA. In this study, we screen and verify insulin-like growth factor-2 mRNA binding protein 1 (IGF2BP1) as a novel citrullinated protein with significantly elevated citrullinated level in RA. Autoantibodies against citrullinated IGF2BP1 are further detected in serum and synovial fluid samples from RA patients, which are positively correlated with erythrocyte sedimentation rate (ESR) and disease activity score 28 (DAS28). Transcriptomic sequencing and functional verification show that citrullination at the R167 site of IGF2BP1 promotes the proliferation, migration, and invasion of RA fibroblast-like synoviocytes (RA-FLSs) by improving the mRNA stability of Semaphorin 3D (SEMA3D). Experiments in collagen-induced arthritis (CIA) mice, the classical animal model of RA, show that IGF2BP1 R176K point mutation (Igf2bp1^R167K/R167K) mice exert reduced inflammatory response, clinical scores, and joint destruction. At a molecular level, citrullination of IGF2BP1 promotes the stability of SEMA3D mRNA by promoting the interaction between IGF2BP1 and its cofactor ELAV-like protein 1 (ELAVL1), thereby promoting the invasiveness of RA-FLSs. In this study, a new citrullinated protein of IGF2BP1 is discovered, and the molecular mechanism of its citrullinated modification promoting the progression of RA disease is elucidated, which provides theoretical basis for the diagnosis and treatment of RA.

Sepsis-induced acute lung injury (ALI) is a life-threatening condition associated with high mortality rates. While emerging evidence suggests that KIAA1199 (also known as cell migration-inducing protein, CEMIP) contributes to the pathogenesis of bacterial infections, its specific role in sepsis-induced ALI remains largely unexplored. In this study, we find that serum levels of KIAA1199 are significantly elevated in sepsis patients compared to healthy individuals, demonstrating a positive correlation with the SOFA scores. Additionally, we observe the expression of KIAA1199 increased in the lung tissue of septic mice, particularly in alveolar epithelial Type II (AT2) cells. We further generate AT2-specific KIAA1199 knockout mice on a male C57BL/6 J background and establish LPS-induced ALI model. The results indicate that KIAA1199-deficient mice exhibit improved survival rates, reduced lung injury, and decreased levels of proinflammatory cytokines. Transcriptomic analysis and functional validation reveal that KIAA1199 promotes pulmonary complement activation by downregulating complement factor H (CFH), a critical regulator of the alternative complement pathway. Mechanistically, KIAA1199 downregulates CFH expression by enhancing the ubiquitinated degradation of its transcription factor of p53. In conclusion, our data demonstrate that KIAA1199 exacerbates sepsis-induced ALI via promoting local complement activation through CFH suppression, which may serve as a potential therapeutic target for sepsis-induced ALI. The alternative text for this image may have been generated using AI.