A novel long noncoding RNA ENST00000597482 serves as a potential biomarker for disease activity and diagnosis of systemic lupus erythematosus.

OBJECTIVES: Emerging evidence indicate that long noncoding RNAs (lncRNAs) may play an important role in the pathogenesis of systemic lupus erythematosus (SLE) however, the contribution of lncRNAs to SLE remains largely unclear. Our study aimed to explore the lncRNA expression profiles in peripheral blood mononuclear cells (PBMCs) from SLE patients. METHODS: LncRNA sequencing was used to detect differentially expressed genes in PBMCs from 5 SLE-MIX samples and 3 healthy controls (HC)-MIX samples, and the expression of selected lncRNAs was further verified by real-time quantitative polymerase chain reaction (RT‒qPCR). The correlation of lncRNA expression with laboratory indicators as well the SLE disease activity index 2000 (SLEDAI‒2K) score from 72 SLE patients was assessed by Spearman's test. The association between lncRNA ENST00000597482 and organ involvement in SLE patients was determined by the Mann‒Whitney U test. Moreover, lymphocyte subsets in peripheral blood from SLE patients were measured by flow cytometry. In addition, the diagnostic value of lncRNAs in predicting SLE was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: The lncRNA expression profiles demonstrated 218 differentially expressed lncRNAs, including 121 upregulated genes and 97 downregulated genes, in PBMCs from SLE patients compared to HCs. Among the 10 candidate genes selected, only lncRNA ENST00000597482, which was lower in SLE PBMCs than in HCs, was consistent with the sequencing results. LncRNA ENST00000597482 expression was negatively correlated with SLEDAI-2K score and the titres of ANA antibodies and anti-double-stranded DNA (anti-dsDNA) antibodies. Of note, SLE patients with lower expression of lncRNA ENST00000597482 were prone to develop organ involvement. Furthermore, lncRNA ENST00000597482 exhibited potential diagnostic value in differentiating SLE patients from HCs. CONCLUSIONS: LncRNA ENST00000597482 expression was lower in PBMCs from SLE patients than HCs and was negatively correlated with the SLEDAI-2K score and autoantibody titres. In addition, lncRNA ENST00000597482 could act as a novel biomarker for disease activity and diagnosis of SLE.

FTO-mediated RNA m6A methylation regulates synovial aggression and inflammation in rheumatoid arthritis.

Fibroblast-like synoviocytes (FLS) plays an important role in synovial inflammation and joint damage in rheumatoid arthritis (RA). As the most abundant mRNA modification, N6-methyladenosine (m6A) is involved in the development of various diseases; however, its role in RA remains to be defined. In this study, we reported the elevated expression of the m6A demethylase fat mass and obesity-associated protein (FTO) in FLS and synovium from RA patients. Functionally, FTO knockdown or treatment with FB23-2, an inhibitor of the mRNA m6A demethylase FTO, inhibited the migration, invasion and inflammatory response of RA FLS, however, FTO-overexpressed RA FLS exhibited increased migration, invasion and inflammatory response. We further demonstrated that FTO promoted ADAMTS15 mRNA stability in an m6A-IGF2BP1 dependent manner. Notably, the severity of arthritis was significantly reduced in CIA mice with FB23-2 administration or CIA rats with intra-articular injection of FTO shRNA. Our results illustrate the contribution of FTO-mediated m6A modification to joint damage and inflammation in RA and suggest that FTO might be a potential therapeutic target in RA.

NAT10 promotes synovial aggression by increasing the stability and translation of N4-acetylated PTX3 mRNA in rheumatoid arthritis.

OBJECTIVE: Recent studies indicate that N-acetyltransferase 10 (NAT10)-mediated ac4C modification plays unique roles in tumour metastasis and immune infiltration. This study aimed to uncover the role of NAT10-mediated ac4C in fibroblast-like synoviocytes (FLSs) functions and synovial immune cell infiltration in rheumatoid arthritis (RA). METHODS: FLSs were obtained from active established patients with RA. Protein expression was determined by western blotting or immunohistochemistry or multiplexed immunohistochemistry. Cell migration was measured using a Boyden chamber. ac4C-RIP-seq combined with RNA-seq was performed to identify potential targets of NAT10. RNA immunoprecipitation was used to validate the interaction between protein and mRNA. NAT10 haploinsufficiency, inhibitor remodelin or intra-articular Adv-NAT10 was used to suppress arthritis in mice with delayed-type hypersensitivity arthritis (DYHA) and collagen II-induced arthritis (CIA) and rats with CIA. RESULTS: We found elevated levels of NAT10 and ac4C in FLSs and synovium from patients with RA. NAT10 knockdown or specific inhibitor treatment reduced the migration and invasion of RA FLSs. Increased NAT10 level in the synovium was positively correlated with synovial infiltration of multiple types of immune cells. NAT10 inhibition in vivo attenuated the severity of arthritis in mice with CIA and DTHA, and rats with CIA. Mechanistically, we explored that NAT10 regulated RA FLS functions by promoting stability and translation efficiency of N4-acetylated PTX3 mRNA. PTX3 also regulated RA FLS aggression and is associated with synovial immune cell infiltration. CONCLUSION: Our findings uncover the important roles of NAT10-mediated ac4C modification in promoting rheumatoid synovial aggression and inflammation, indicating that NAT10 may be a potential target for the treatment of RA, even other dysregulated FLSs-associated disorders.

Response to belimumab among patients with refractory lupus nephritis: a real-world observational retrospective multicenter study.

OBJECTIVES: Belimumab is a biological agent approved for the treatment of active lupus nephritis (LN), but its efficacy on refractory lupus nephritis (LN) is unknown. This study aims to evaluate the efficacy and safety of belimumab in Chinese patients with refractory LN. METHODS: This multicenter, observational, and retrospective study enrolled patients with refractory LN who failed induction therapy with steroids, cyclophosphamide, mycophenolate, and calcineurin inhibitors and received 24-week belimumab treatment before data analysis. Treatment outcomes include the overall clinical response (physician judgment, disease activity, organ damage) and renal response (complete renal response, partial renal response, no renal response). Laboratory indices and adverse events were recorded as well. RESULTS: Of the 45 patients enrolled in the study, 6 (13.3%) achieved complete renal response, 19 (42.2%) achieved partial renal response, and the overall renal response rate was 55.6%. Median rSLEDAI decreased from 12 (IQR 8-12) at baseline to 8 (IQR 4-8) (p < 0.0001), 4 (IQR 4-8) (p < 0.0001) at 12 and 24 weeks. Mean urinary protein decreased more than 50% from 3.2 g/24 h at baseline to 1.0 g/24 h at 24 weeks (p < 0.0001). The conditions of hypoalbuminemia and hypocomplementemia had also gradually improved. The levels of autoantibodies showed a significant downward trend. Additionally, 9 (20.0%) patients successfully reduced the dosage of prednisone to a safe range, and 3 of them achieved their treatment goal of prednisone cessation. The mean prednisone dosage decreased from 32.7 mg/day at baseline to 18.6 mg/day (p < 0.0001), 13.3 mg/day (p < 0.0001) at 12 and 24 weeks. There were 3 adverse events reported, including 2 cases of infection, and 1 case of allergy. No serious events occurred during the follow-up. CONCLUSIONS: Belimumab is effective and safe when used in clinical practice, which can be considered as an add-on therapy for refractory LN. Key Points • A multicenter observational study in the real clinical settings of China. • First revealed the efficacy and safety of belimumab in Chinese patients with refractory LN.

ALKBH5-Mediated RNA m6 A Methylation Regulates the Migration, Invasion, and Proliferation of Rheumatoid Fibroblast-Like Synoviocytes.

OBJECTIVE: Fibroblast-like synoviocytes (FLSs) are critical for promoting joint damage in rheumatoid arthritis (RA). N6 -methyladenosine (m6 A) modification plays key roles in various diseases, but its role in the pathogenesis of RA is largely unknown. Here, we investigate increased demethylase ALKBH5 promotion of proliferation, migration, and invasion of RA FLSs via regulating JARID2 expression. METHODS: ALKBH5 expression in FLSs was evaluated using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot. 5-ethynyl-2'-deoxyuridine, scratch wound healing, and transwell assays were implemented to determine the role of ALKBH5 on RA FLS proliferation, mobility, and migration. Then, m6 A sequencing combined with RNA sequencing was performed to identify the potential targets of ALKBH5. RNA immunoprecipitation and RNA pulldown were then used to validate the interaction between the protein and messenger RNA (mRNA). Collagen-induced arthritis (CIA) and delayed-type hypersensitivity arthritis (DTHA) models were further established to assess the therapeutic potency of ALKBH5 in vivo. RESULTS: We demonstrated that ALKBH5 expression was increased in FLSs and synovium from RA. Functionally, ALKBH5 knockdown inhibited the proliferation, migration, and invasion of RA FLSs, whereas overexpression of ALKBH5 displayed the opposite effect. Mechanistically, ALKBH5 mediated m6 A modification in the JARID2 mRNA and enhanced its mRNA stability in cooperation with IGF2BP3. Intriguingly, the severity of arthritis was attenuated in mice with DTHA and ALKBH5 knockout or rats with CIA and intra-articular injection of ALKBH5 short hairpin RNA. CONCLUSION: Our findings suggest that ALKBH5-mediated m6 A modification is crucial for synovial hyperplasia and invasion in RA. ALKBH5 might be a potential therapeutic target for RA and even for dysregulated fibroblasts in a wide range of diseases.

Schisandrin treatment suppresses the proliferation, migration, invasion, and inflammatory responses of fibroblast-like synoviocytes from rheumatoid arthritis patients and attenuates synovial inflammation and joint destruction in CIA mice.

BACKGROUND: Rheumatoid arthritis (RA) is a systemic autoimmune disease causing joint dysfunction. As disease-modifying anti-rheumatic drugs (DMARDs) have poor efficacy in 20% to 25% of RA patients, additional novel RA medications are urgently needed. Schisandrin (SCH) has multiple therapeutic effects. However, whether SCH is effective against RA remains unknown. PURPOSE: To investigate how SCH affects the abnormal behaviours of RA fibroblast-like synoviocytes (FLSs) and further elucidate the underlying mechanism of SCH in RA FLSs and collagen-induced arthritis (CIA) mice. METHODS: Cell Counting Kit-8 (CCK8) assays were used to characterize cell viability. EdU assays were performed to assess cell proliferation. Annexin V-APC/PI assays were used to determine apoptosis. Transwell chamber assays were used to measure cell migration and invasion in vitro. RT-qPCR was used to assess proinflammatory cytokine and MMP mRNA expression. Western blotting was used to detect protein expression. RNA sequencing was performed to explore the potential downstream targets of SCH. CIA model mice were used to assess the treatment efficacy of SCH in vivo. RESULTS: Treatments with SCH (50, 100, and 200 µΜ) inhibited RA FLSs proliferation, migration, invasion, and TNF-α-induced IL-6, IL-8, and CCL2 expression in a dose-dependent manner but did not affect RA FLSs viability or apoptosis. RNA sequencing and Reactome enrichment analysis indicated that SREBF1 might be the downstream target in SCH treatment. Furthermore, knockdown of SREBF1 exerted effects similar to those of SCH in inhibiting RA FLSs proliferation, migration, invasion, and TNF-α-induced expression of IL-6, IL-8, and CCL2. Both SCH treatment and SREBF1 knockdown decreased activation of the PI3K/AKT and NF-κB signalling pathways. Moreover, SCH ameliorated joint inflammation and cartilage and bone destruction in CIA model mice. CONCLUSION: SCH controls the pathogenic behaviours of RA FLSs by targeting SREBF1-mediated activation of the PI3K/AKT and NF-κB signalling pathways. Our data suggest that SCH inhibits FLS-mediated synovial inflammation and joint damage and that SCH might have therapeutic potential for RA.

Non-invasive left ventricular myocardial work identifies subclinical myocardial involvement in patients with systemic lupus erythematosus.

OBJECTIVE: Global myocardial work (MW) is a novel indicator that accounts for deformation and afterload, which may provide additional value for assessment of myocardial function. Non-invasive echocardiographic estimated left ventricular (LV) MW incorporates longitudinal strain curves and blood pressure data. This study sought to assess MW in systemic lupus erythematosus (SLE) patients with normal LV ejection fraction (LVEF) by two-dimensional speckle-tracking imaging (2D-STI) to reflect subclinical myocardial damage. METHODS: 98 SLE patients and 98 gender and age-matched healthy subjects were included. The patients with SLE were divided into mild activity (SLE disease activity index (SLEDAI) ≤ 4; n = 45), moderate activity (5 ≤ SLEDAI ≤ 9; n = 23), and high activity (SLEDAI ≥ 10; n = 30) subgroups. Standard transthoracic echocardiography was applied to evaluate the systolic myocardial function of the global LV. The parameters of non-invasive MW including global wasted work (GWW) and global work efficiency (GWE) were calculated from echocardiographic LV pressure-strain loops (PSL) and blood pressure at rest. RESULTS: The SLE group had a significantly higher GWW (75.7 ± 39.1 mmHg% vs 37.9 ± 18.0 mmHg%, P < 0.001) and decreased GWE ratio (95.5 ± 2.0% vs 97.4 ± 1.0%, P < 0.001) compared with the controls. Among the subgroups with elevating level of disease activity, SLE patients with preserved LVEF had a significantly higher GWW (61.6 ± 29.9 mmHg% to 96.2 ± 42.2 mmHg%, P for trend = 0.001) and markedly decreased GWE (96.4 ± 1.5% to 94.4 ± 2.0%, P for trend = 0.001). In two separate multiple linear regression analyses, SLEDAI were independently associated with GWW (ß = 0.271, P = 0.005) and GWE (ß = -0.354, P<0.001). CONCLUSION: GWW and GWE are promising novel tools for the early detection of subclinical LV dysfunction. GWW and GWE could distinguish distinct patterns in different grades of SLEDAI.

Long Noncoding RNA HAFML Promotes Migration and Invasion of Rheumatoid Fibroblast-like Synoviocytes.

The aggressive phenotype exhibited by fibroblast-like synoviocytes (FLSs) is critical for the progression of joint destruction in rheumatoid arthritis (RA). Long noncoding RNAs (lncRNAs) have crucial roles in the pathogenesis of diverse disorders; however, few have been identified that might be able to control the joint damage in RA. In this study, we identified an lncRNA, ENST00000509194, which was expressed at abnormally high levels in FLSs and synovial tissues from patients with RA. ENST00000509194 positively modulates the migration and invasion of FLSs by interacting with human Ag R (HuR, also called ELAVL1), an RNA-binding protein that mainly stabilizes mRNAs. ENST00000509194 binds directly to HuR in the cytoplasm to form a complex that promotes the expression of the endocytic adaptor protein APPL2 by stabilizing APPL2 mRNA. Knockdown of HuR or APPL2 impaired the migration and invasion of RA FLSs. Given its close association with HuR and FLS migration, we named ENST00000509194 as HAFML (HuR-associated fibroblast migratory lncRNA). Our findings suggest that an increase in synovial HAFML might contribute to FLS-mediated rheumatoid synovial aggression and joint destruction, and that the lncRNA HAFML might be a potential therapeutic target for dysregulated fibroblasts in a wide range of diseases.

SMOC2 promotes aggressive behavior of fibroblast-like synoviocytes in rheumatoid arthritis through transcriptional and post-transcriptional regulating MYO1C.

Fibroblast-like synoviocytes (FLSs), play a key role in perpetuating synovial inflammation and bone erosion in rheumatoid arthritis (RA), however, the underlying mechanism(s) of RA FLSs activation and aggression remain unclear. Identifying endogenous proteins that selectively target FLSs is urgently needed. Here, we systematically identified that secreted modular calcium-binding protein 2 (SMOC2), was significantly increased in RA FLSs and synovial tissues. SMOC2 knockdown specifically regulated cytoskeleton remodeling and decreased the migration and invasion of RA FLSs. Mechanistically, cytoskeleton-related genes were significantly downregulated in RA FLSs with reduced SMOC2 expression, especially the motor protein myosin1c (MYO1C). SMOC2 controlled MYO1C expression by SRY-related high-mobility group box 4 (SOX4) and AlkB homolog 5 (ALKHB5) mediated-m6A modification through transcriptional and post-transcriptional regulation. Furthermore, intra-articular Ad-shRNA-SMOC2 treatment attenuated synovial inflammation as well as bone and cartilage erosion in rats with collagen-induced arthritis (CIA). Our findings suggest that increased SMOC2 expression in FLSs may contribute to synovial aggression and joint destruction in RA. SMOC2 may serve as a potential target against RA. SMOC2-mediated regulation of the synovial migration and invasion in RA FLSs. In RA FLSs, SMOC2 is significantly increased, leading to the increased level of MYO1C via SOX4-mediated transcriptional regulation and ALKBH5-mediated m6A modification, thereby causing cytoskeleton remodeling and promoting RA FLSs migration and invasion. The Figure was drawn by Figdraw.

Myricitrin inhibits fibroblast-like synoviocyte-mediated rheumatoid synovial inflammation and joint destruction by targeting AIM2.

Objective: To explore the effect and underlying mechanism of Myricitrin (Myr) in regulating fibroblast-like synoviocyte (FLS)-mediated synovitis and joint destruction in RA. Methods: FLSs were isolated from synovial tissues from patients with RA. Gene expression was measured using quantitative RT-qPCR. Protein expression was detected by immunohistochemistry or Western blot. Cell apoptosis was performed by an Annexin-PI staining assay. EdU incorporation was used to assess the proliferation of RA FLS. Transwell assay was used to characterize the cell migration and invasion ability of RA FLS. The potential target of Myr was identified by RNA sequencing analysis. The in vivo effect of Myr was assessed in a collagen-induced arthritis (CIA) model. Results: Myr treatment inhibited the lamellipodia formation, migration, and invasion, but not the apoptosis and proliferation, of RA FLSs. Myr also reduced the expression of CCL2, IL-6, IL-8, MMP-1, MMP-3, and MMP-13 induced by TNF-α. The RNA-seq results indicated that AIM2 may be a target gene of Myr in RA FLSs. Furthermore, compared to healthy controls, AIM2 expression showed higher levels in synovial tissues and FLSs from RA patients. AIM2 knockdown also inhibited RA FLS migration, invasion, cytokine, and MMP expression. In addition, either Myr treatment or AIM2 knockdown reduced the phosphorylation of AKT induced by TNF-α stimulation. Importantly, Myr administration relieved arthritis symptoms and inhibited AIM2 expression in the synovium of CIA mice. Conclusion: Our results indicate that Myr exerts an anti-inflammatory and anti-invasion effect in RA FLSs and provide evidence of the therapeutic potential of Myr for RA.

Postsystolic shortening and early systolic lengthening for early detection of myocardial involvement in patients with systemic lupus erythematosus.

BACKGROUND: Cardiac involvement predicts a poor prognosis in patients with systemic lupus erythematosus (SLE). Two-dimensional speckle-tracking echocardiography (2D-STE) are used to identify subclinical myocardial involvement in various diseases. This study objected to evaluate postsystolic shortening (PSS) and early systolic lengthening (ESL) by 2D-STE for early detection of myocardial involvement in patients with SLE. METHODS: A total of 121 patients with preserved left ventricular ejection fraction (LVEF) in SLE and 30 healthy controls underwent standard 2D-STE in our study. According to SLE disease activity index (SLEDAI), we divided SLE patients into two groups: the group of inactive disease (SLEDAI ≤ 4) and active disease (SLEDAI ≥ 5). The maximum of postsystolic strain index (PSImax ) and early systolic strain index (ESImax ) were acquired from 17 segments of left ventricular (LV). We also compared the PSImax and ESImax of basal, medial, and apical segments between SLE patients and controls. RESULTS: Compared with healthy controls and the group of SLEDAI ≤ 4, the group of SLEDAI ≥ 5 had higher PSImax and ESImax value of global LV and basal segments. The absolute value of global longitudinal strain (GLS) had no difference between the group of active disease and inactive disease. Multivariate analysis demonstrated that PSS was independently associated with SLEDAI and diabetes mellitus. CONCLUSIONS: Detection of PSS and ESL enable to identify LV systolic impairment in SLE patients at an early stage.

cGAS/STING signaling in the regulation of rheumatoid synovial aggression.

Background: Fibroblast-like synoviocytes (FLSs) play a critical role in promoting synovial aggression and joint destruction in rheumatoid arthritis (RA). Cyclic GMP-AMP synthase (cGAS)/stimulator of interferon gene (STING) signaling plays an important role in controlling a series of cellular biological processes. However, it is still unclear whether cGAS/STING signaling regulates rheumatoid synovial aggression. Methods: Cell migration and invasion were detected using a Transwell chamber. Gene expression was measured using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and protein expression was detected by western blotting. Reactive oxygen species (ROS) levels were measured by 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) probe. F-actin staining and immunofluorescence assays were used to investigate lamellipodia formation and nuclear translocation, respectively. A severe combined immunodeficiency (SCID) mouse model was established to observe the migration and invasion of RA FLSs in vivo. Results: Our results showed that cytosolic double-stranded DNA (dsDNA)-induced cGAS/STING activation promoted the in vitro migration and invasion of RA FLSs. Moreover, RA FLSs treated with cGAS or STING short hairpin RNA (shRNA) exhibited reduced invasion into cartilage in the SCID model. Mechanistically, we determined that cGAS/STING activation leads to increased mitochondrial ROS levels, and thereby increases phosphorylation of mammalian sterile 20-like kinase 1 (MST1), a core component of the Hippo pathway, subsequently promoting activation of forkhead box1 (FOXO1). MST1 and FOXO1 knockdown also diminished the migration and invasion of RA FLSs. Conclusions: Our findings suggest that cGAS/STING signaling has an important role in regulating rheumatoid synovial aggression and that targeting cGAS/STING may represent a novel potential therapy for RA.

Impaired left ventricular systolic synchrony in patients with lupus Nephritis: A speckle tracking echocardiography study.

OBJECTIVES: We aimed to explore the value of two-dimensional speckle tracking echocardiography measurements of the global longitudinal strain (GLS) and left ventricular mechanical dispersion (LVMD) in the assessment of early stage left ventricular systolic dysfunction and heterogeneity of myocardial contraction in patients with lupus nephritis (LN). METHODS: Patients with LN and extra-renal systemic lupus erythematosus (SLE) and healthy participants in the control group underwent echocardiography for the traditional measurement of the left ventricular systolic and diastolic function and speckle tracking measurements of the GLS and LVMD. GLS was defined as the average value of the peak strain during systole of the left ventricular 17 segments, and LVMD was defined as the standard deviation. The demographic characteristics including age, sex, and body mass index (BMI) of all the participants were collected. The clinical and laboratory characteristics of the patients with LN were collected. RESULTS: We included 41 healthy control, 37 patients with extra-renal SLE, and 73 patients with LN. There were statistically significant differences in the GLS and LVMD between the extra-renal SLE and LN groups (GLS -19.36% vs. -17.61%, p < 0.001; LVMD 35.62 ms vs 42.96 ms, p<0.001). There was a statistically significant difference in the LVMD between the extral-renal SLE and control groups (35.62ms vs 25.51ms, p<0.001), but not in GLS (-19.36% vs -19.52%, p > 0.05). Multiple regression analyses were conducted in a subset of patients, and 24-hour proteinuria was independently associated with LVMD (ß [SE], 0.793 [0.302], p < .05). CONCLUSIONS: Patients with LN have more severe myocardial involvement than patients with extra-renal SLE. The asynchrony in myocardial contraction represented by the LVMD can be recognized earlier than that of the overall contractile functional impairment represented by GLS. In patients with LN, the 24-hour proteinuria was associated with LVMD. This indicates that the heterogeneity in the contractile function may be associated with the severity of renal damage.

The suppression of Brd4 inhibits peripheral plasma cell differentiation and exhibits therapeutic potential for systemic lupus erythematosus.

The mechanisms that control B cell terminal differentiation remain undefined. Here, we investigate the role of bromodomain-containing protein 4 (Brd4) in regulating B cell differentiation and its therapeutic potential for B cell-mediated autoimmune diseases including systemic lupus erythematosus (SLE). We showed that Brd4 inhibitor PFI-1 suppressed plasmablast-mediated plasma cell differentiation in healthy human CD19+ B cells. PFI-1 reduced IgG and IgM secretion in costimulation-induced human B cells. We also observed a reduced percentage of plasma cells in mice with B cell-specific deletion of the Brd4 gene (Brd4flox/floxCD19-cre+). Mechanistically, using the luciferase reporter assay and the chromatin immunoprecipitation, we explored that Brd4 regulates the expression of B lymphocyte-induced maturation protein 1 (BLIMP1), an important transcript factor that is involved in modulation of plasma cell differentiation. Interestingly, PFI-1 decreased the percentages of plasmablasts and plasma cells from patients with SLE. PFI-1 administration reduced the percentages of plasma cells, hypergammaglobulinemia, and attenuated nephritis in MRL/lpr lupus mice. Pristane-injected Brd4flox/floxCD19-cre+ mice exhibited improved nephritis and reduced percentages of plasma cells. These findings suggest an essential factor of Brd4 in regulating plasma cell differentiation. Brd4 inhibition may be a potential strategy for the treatment of B cell-associated autoimmune disorders.

Increased long noncoding RNA LINK-A contributes to rheumatoid synovial inflammation and aggression.

Fibroblast-like synoviocytes (FLSs) play a key role in controlling synovial inflammation and joint destruction in rheumatoid arthritis (RA). The contribution of long noncoding RNAs (lncRNAs) to RA is largely unknown. Here, we show that the lncRNA LINK-A, located mainly in cytoplasm, has higher-than-normal expression in synovial tissues and FLSs from patients with RA. Synovial LINK-A expression was positively correlated with the severity of synovitis in patients with RA. LINK-A knockdown decreased migration, invasion, and expression and secretion of matrix metalloproteinases and proinflammatory cytokines in RA FLSs. Mechanistically, LINK-A controlled RA FLS inflammation and invasion through regulation of tyrosine protein kinase 6-mediated and leucine-rich repeat kinase 2-mediated HIF-1α. On the other hand, we also demonstrate that LINK-A could bind with microRNA 1262 as a sponge to control RA FLS aggression but not inflammation. Our findings suggest that increased level of LINK-A may contribute to FLS-mediated rheumatoid synovial inflammation and aggression. LINK-A might be a potential therapeutic target for RA.

Nitidine chloride inhibits fibroblast like synoviocytes-mediated rheumatoid synovial inflammation and joint destruction by targeting KCNH1.

OBJECTIVE: Nitidine chloride (NC), a natural small molecular compound from traditional Chinese herbal medicine zanthoxylum nitidum, has been shown to exhibit anti-tumor effect. However, its role in autoimmune diseases such as rheumatoid arthritis (RA) is unknown. Here, we investigate the effect of NC in controlling fibroblast-like synoviocytes (FLS)-mediated synovial inflammation and joint destruction in RA and further explore its underlying mechanism(s). METHODS: FLSs were separated from synovial tissues obtained from patients with RA. Protein expression was analyzed by Western blot or immunohistochemistry. Gene expression was measured using quantitative RT-PCR. ELISA was used to measure the levels of cytokines and MMPs. Cell proliferation was detected using EdU incorporation. Migration and invasion were evaluated by Boyden chamber assay. RNA sequencing analysis was used to identify the target of NC. Collagen-induced arthritis (CIA) model was used to evaluate the in vivo effect of NC. RESULTS: NC treatment reduced the proliferation, migration, invasion, and lamellipodia formation but not apoptosis of RA FLSs. We also demonstrated the inhibitory effect of NC on TNF-α-induced expression and secretion of IL-6, IL-8, CCL-2, MMP-1 and MMP-13. Furthermore, we identified KCNH1, a gene that encodes ether-à-go-go-1 channel, as a novel targeting gene of NC in RA FLSs. KCNH1 expression was increased in FLSs and synovial tissues from patients with RA compared to healthy controls. KCNH1 knockdown or NC treatment decreased the TNF-α-induced phosphorylation of AKT. Interestingly, NC treatment ameliorated the severity of arthritis and reduced synovial KCNH1 expression in mice with CIA. CONCLUSIONS: Our data demonstrate that NC treatment inhibits aggressive and inflammatory actions of RA FLSs by targeting KCNH1 and sequential inhibition of AKT phosphorylation. Our findings suggest that NC might control FLS-mediated rheumatoid synovial inflammation and joint destruction, and be a novel therapeutic agent for RA.

Increased SUMO-activating enzyme SAE1/UBA2 promotes glycolysis and pathogenic behavior of rheumatoid fibroblast-like synoviocytes.

Fibroblast-like synoviocytes (FLSs) are critical to joint inflammation and destruction in rheumatoid arthritis (RA). Increased glycolysis in RA FLSs contributes to persistent joint damage. SUMOylation, a posttranslational modification of proteins, plays an important role in initiation and development of many diseases. However, the role of small ubiquitin-like modifier-activating (SUMO-activating) enzyme 1 (SAE1)/ubiquitin like modifier activating enzyme 2 (UBA2) in regulating the pathogenic FLS behaviors is unknown. Here, we found an increased expression of SAE1 and UBA2 in FLSs and synovial tissues from patients with RA. SAE1 or UBA2 knockdown by siRNA and treatment with GA, an inhibitor of SAE1/UBA2-mediated SUMOylation, resulted in reduced glycolysis, aggressive phenotype, and inflammation. SAE1/UBA2-mediated SUMOylation of pyruvate kinase M2 (PKM2) promoted its phosphorylation and nuclear translocation and decreased PK activity. Moreover, inhibition of PKM2 phosphorylation increased PK activity and suppressed glycolysis, aggressive phenotype, and inflammation. We further demonstrated that STAT5A mediated SUMOylated PKM2-induced glycolysis and biological behaviors. Interestingly, GA treatment attenuated the severity of arthritis in mice with collagen-induced arthritis and human TNF-α transgenic mice. These findings suggest that an increase in synovial SAE1/UBA2 may contribute to synovial glycolysis and joint inflammation in RA and that targeting SAE1/UBA2 may have therapeutic potential in patients with RA.

Infective patterns of cryptococcosis in patients with connective tissue disease: a retrospective study.

OBJECTIVES: To explore the clinical features and associated factors of cryptococcosis in patients with connective tissue disease (CTD) from Southern China. METHODS: Demographic and clinical data were collected between 2007 and 2018. Associated factors were analyzed by logistic regression analysis. RESULTS: A total of 6809 inpatients with CTD were included. Cryptococcosis was diagnosed in 30 patients (prevalence, 0.4%). Cryptococcosis was predominant in patients with ANCA-associated vasculitis (AAV) (prevalence, 6/530, 1.1%). Lung was commonly involved (18/30, 60.0%), followed by meninges (6/30, 20.0%), blood stream (5/30, 16.7%), and disseminated cryptococcosis (involved blood stream and meninges) (1/30, 3.3%). Infiltrates (10/18, 55.6%) and small nodules (8/18, 44.4%) were the main radiographic manifestation of pulmonary cryptococcosis (PC). The positive rate of serum cryptococcal antigen (CrAg) in patients with PC was 88.2%. Cryptococcus spp. were found in 75% (3/4) patients who underwent lung biopsy. Most of the patients with cryptococcal meningitis (CM) had elevated cerebrospinal fluid (CSF) opening pressure (6/7, 85.7%) and decreased CSF glucose level (5/7, 71.4%). Positive blood culture confirmed the diagnosis of cryptococcal sepsis (CS). Three patients died (10.0%), including one with CM and two with PC. Multivariate logistic regression analysis showed that accumulated dose of glucocorticoid (GC) [odds ratio (OR) = 1.42, 95% confidence interval (CI) 1.04-1.93, P = 0.03] was associated with cryptococcosis in patients with CTD. CONCLUSIONS: Cryptococcosis develops in various organs. Typical radiological manifestation accompanied with positive serum CrAg provides helpful clues for the diagnosis. Lumbar puncture is a critical diagnostic method to distinguish CM. The accumulated dose of GC is associated with cryptococcosis in patients with CTD. Key Points • Pulmonary cryptococcosis is suspected if pulmonary nodules adjacent to the pleura are present, with serum CrAg positive. • Cryptococcal meningitis has insidious onset and the diagnosis mainly depends on lumber puncture. • Cryptococcal sepsis is not rare and needs timely blood culture in suspected patients.

Accumulation of cytosolic dsDNA contributes to fibroblast-like synoviocytes-mediated rheumatoid arthritis synovial inflammation.

The accumulation of cytosolic dsDNA plays important roles in the regulation of cellular processes. However, whether cytosolic dsDNA is involved in the pathogenesis of rheumatoid arthritis (RA) is not clear. Therefore, the present study investigated the roles of cytosolic dsDNA in the modulation of inflammatory responses of fibroblast-like synoviocytes (FLS) in patients with RA. FLS were obtained from active RA patients. dsDNA accumulation in the cytosol was detected by immunofluorescence staining and the Qubit® dsDNA HS Assay. Immunohistochemistry was employed to detect the dsDNA and cGMP-AMP synthase (cGAS) expression in the synovium. Short hairpin RNA (shRNA) was used to knockdown the expression of cGAS and stimulator of interferon genes (STING). Protein expression was detected by Western blotting and immunofluorescence staining. We observed increased cytosolic dsDNA and cGAS expression in FLS and synovium from RA patients. dsDNA and cGAS expression correlated with the severity of rheumatoid synovitis. Transfection of dsDNA into the cytosol of RA FLS promoted pro-inflammatory cytokines production. DNaseII overexpression downregulated cytosolic dsDNA expression and inhibited dsDNA-induced cytokines secretion. We also found that dsDNA and TNF-α enhanced cGAS and STING expression, and dsDNA-induced cytokine secretion was reduced by cGAS or STING knockdown. Furthermore, we determined that the dsDNA-induced phosphorylation of IRF3 and NF-κBp65 was decreased by DNaseII overexpression or cGAS/STING knockdown. Overall, our findings show that increased cytosolic dsDNA level promoted inflammatory responses via the cGAS/STING pathway in RA FLS, which suggests that cytosolic dsDNA accumulation is an important contributor to FLS-mediated rheumatoid synovial inflammation.

Invasive mycoses in patients with connective tissue disease from Southern China: clinical features and associated factors.

BACKGROUND: A retrospective study was performed to investigate the clinical features and associated factors of invasive mycoses (IM) in patients with connective tissue disease (CTD) from Southern China. METHODS: Demographic and clinical data were recorded. Associated factors were analyzed by logistic regression analysis. RESULTS: A total of 6911 patients with CTD were included. IM was diagnosed in 32 patients (incidence, 0.5%). IM was predominant in patients with ANCA-associated vasculitis (AAV) (incidence, 1.5%, 7/480). Lung was commonly involved (30/32, 93.8%). Aspergillus spp. (81.3%) were the leading strain. The positive rate of fungi detection in sputum culture was 69.0%. Serum galactomannan (GM) test was positive in bronchoalveolar lavage fluid (BALF) from seven (7/10, 70.0%) patients. Ten patients died (31.3%), including three with AAV (42.9%) and seven with SLE (36.8%). Penicillium marneffei was the most fatal (mortality, 100%). Non-survivors had higher prevalence of leukopenia (30.0% vs 4.5%, P = 0.04), lymphopenia (100.0% vs 59.1%, P = 0.02), elevated serum creatinine (70.0% vs 27.3%, P = 0.02), and co-infection (70.0% vs 18.2%, P = 0.004) than survivors. Multivariate logistic regression analysis showed that lymphopenia [odds ratio (OR) = 3.28, 95% confidence interval (CI) 1.29-8.38, P = 0.01] and median-to-high dose of glucocorticoid (GC) [OR = 3.40, 95% CI 1.04-11.13, P = 0.04] were associated with IM in patients with CTD. CONCLUSIONS: IM tended to develop in patients with AAV, resulting in high mortality. Sputum culture and GM test in BALF were effective methods to distinguish IM. Vigilance against lymphopenia, impaired kidney function, and co-infection improved the prognosis of IM.