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.

Efficacy and safety of tripterygium wilfordii Hook F plus TNF inhibitor for active rheumatoid arthritis: A multicentre, randomized, double-blind, triple-dummy controlled trial.

An investigator-initiated, multicentre, randomized, double-blind, triple-dummy, controlled trial was conducted at 14 tertiary rheumatology centers in China to evaluate the efficacy and safety of Tripterygium wilfordii Hook F (TwHF) with recombinant human TNF receptor IgGFc fusion protein (rhTNFR-Fc) in active Rheumatoid Arthritis (RA). Primary endpoint was the proportion of patients achieved a 50% improvement of American College of Rheumatology criteria (ACR50) in TwHF+rhTNFR-Fc vs. methotrexate (MTX) group at week 12. ACR50 was achieved in 57.1% (72/126), 41.3% (52/126), 23.0% (29/126), and 26.2% (33/126) patients receiving TwHF+rhTNFR-Fc, MTX + rhTNFR-Fc, TwHF and MTX monotherapy, respectively, at week 12 (TwHF+rhTNFR-Fc vs. other three groups, all p < 0.05). No statistical difference in serious adverse events or adverse events leading to discontinuation of study across all groups was documented. TwHF+rhTNFR-Fc was superior to MTX for active RA, and was more effective than MTX + rhTNFR-Fc on ACR50, with a similar safety profile. Trial registration:ClinicalTrials.govNCT03589833.

Interleukin 4-driven reversal of self-reactive B cell anergy contributes to the pathogenesis of systemic lupus erythematosus.

OBJECTIVES: Reactivation of anergic autoreactive B cells (BND cells) is a key aetiological process in systemic lupus erythematosus (SLE), yet the underlying mechanism remains largely elusive. This study aimed to investigate how BND cells participate in the pathogenesis of SLE and the underlying mechanism. METHODS: A combination of phenotypical, large-scale transcriptome and B cell receptor (BCR) repertoire profiling were employed at molecular and single cell level on samples from healthy donors and patients with SLE. Isolated naïve B cells from human periphery blood were treated with anti-CD79b mAb in vitro to induce anergy. IgM internalisation was tracked by confocal microscopy and was qualified by flow cytometer. RESULTS: We characterised the decrease and disruption of BND cells in SLE patients and demonstrated IL-4 as an important cytokine to drive such pathological changes. We then elucidated that IL-4 reversed B cell anergy by promoting BCR recycling to the cell surface via STAT6 signalling. CONCLUSIONS: We demonstrated the significance of IL-4 in reversing B cell anergy and established the scientific rationale to treat SLE via blocking IL-4 signalling, also providing diagnostic and prognostic biomarkers to identify patients who are most likely going to benefit from such treatments.

AOSD endotypes based on immune cell profiles: patient stratification with hierarchical clustering analysis.

OBJECTIVES: This study aimed to analyse the immune cell profiles of adult-onset Still's disease (AOSD) and to stratify disease-associated endotypes. METHODS: We included 95 cases of treatment-naïve patients with AOSD and 66 cases of healthy controls. Patients with AOSD were classified via an unbiased hierarchical cluster analysis based on circulating immune cells. Their clinical and laboratory characteristics, treatment management, systemic scores and outcomes were then analysed. RESULTS: The proportions of neutrophils and CD8+ T cells were significantly higher while monocytes and natural killer and CD4+ T cells were decreased in patients with AOSD (all P < 0.005). Unbiased hierarchical cluster analysis classified 95 AOSD into three endotype-based groups: group 1 had the highest percentage of neutrophils (neu-dominant group), group 2 had the highest percentage of monocytes (mono-dominant group) and group 3 had the highest percentage of CD8+ T cells (CD8-dominant group). Patients in group 3 had the highest systemic score at diagnosis and were more likely to have pulmonary infiltrates, pericarditis, splenomegaly and poorer treatment responses. A correlation study revealed that the CD4 to CD8 ratio was negatively correlated with the systemic score and positively correlated with treatment response in patients with AOSD (P = 0.001 and P = 0.0091). During the 24.6 (15.2) months of follow-up, the highest total number of disease flares occurred in group 3 (P < 0.0001). CONCLUSION: Hierarchical cluster analysis of peripheral immune cells classified AOSD into three disease-related endotypes. Group 3 showed higher systemic score and poorer treatment responses.

Longitudinal study of patients with antimelanoma differentiation-associated gene 5 antibody-positive dermatomyositis-associated interstitial lung disease.

OBJECTIVES: To describe the 8-year longitudinal study and long-term prognosis of a large inception cohort of anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive (MDA5+) DM-interstitial lung disease (ILD) patients. METHODS: In total, 216 patients diagnosed with MDA5+ DM-ILD were enrolled and followed up to analyse long-term survival rate. Demographic and clinical variables were collected at baseline and each temporal end point. Seventy patients who survived the first year were analysed for the long-term serological and respiratory outcomes. RESULTS: A total of 85 patients (39.3%) died during the follow-up period up to 96 months, with 89% of the deaths occurring in the first year after diagnosis. Long-term outcome was reported in 70 patients. Serological markers including anti-MDA5 antibody showed significant improvement with time. Radiographic findings and pulmonary function also improved notably in the follow-up period, especially in rapidly progressive ILD group, as measured by high-resolution computed tomography imaging scores, the estimated forced vital capacity, estimated diffusing capacity of lung carbon monoxide and dyspnoea scores. Early application of anti-fibrosis therapy helped to improve long-term pulmonary function. CONCLUSIONS: MDA5+ DM-ILD patients had a high mortality rate despite aggressive treatment. Patients who survived the first year usually showed a significant improvement in serological markers and pulmonary function during the long-term follow-up.

Serosal involvement in adult-onset Still's disease: A multicentre and retrospective study.

OBJECTIVES: This study evaluated the characteristics of serosal involvement in adult-onset Still's disease (AOSD). METHODS: Patients meeting the Yamaguchi classification criteria were classified into AOSD with and without serosal involvement according to their manifestations and sonography/radiography. Clinical data was retrospectively reviewed from 102 patients with AOSD in two centres. RESULTS: Forty-two patients (41.2%) had serosal involvement. The frequencies of pulmonary infiltrate and impaired liver function were significantly higher in patients with serosal involvement (p = .002 and p = .007, respectively), who also had a higher modified systemic score (p = .009). In addition, the percentages of CD3+ T cells (p < .001) and, especially, the CD8+ T cells (p = .004) were significantly increased in the peripheral blood of AOSD patients with serosal involvement. Notably, patients with serosal involvement were more likely to develop macrophage activation syndrome (p = .047) and a chronic pattern (p = .016) during the follow-up. CONCLUSIONS: Patients with serosal involvement demonstrated the more severe disease activity and different immune phenotypes; these patients were more likely to develop macrophage activation syndrome, and they may require more aggressive treatment at an early time to control their systemic inflammation.

Leflunomide versus azathioprine for maintenance therapy of lupus nephritis: a prospective, multicentre, randomised trial and long-term follow-up.

OBJECTIVES: Previous studies have compared mycophenolate mofetil and azathioprine as maintenance therapy for lupus nephritis (LN). Leflunomide is an immunosuppressant widely used in the treatment of rheumatoid arthritis. The aim of this investigator-initiated study was to compare the efficacy and safety of leflunomide versus azathioprine as maintenance therapy for LN. METHODS: 270 adult patients with biopsy-confirmed active LN from 7 Chinese Rheumatology Centres were enrolled. All patients received induction therapy with 6-9 months of intravenous cyclophosphamide plus glucocorticoids. Patients who achieved complete response (CR) or partial response (PR) were randomised to receive prednisone in combination with leflunomide or azathioprine as maintenance therapy for 36 months. The primary efficacy endpoint was the time to kidney flare. Secondary outcomes included clinical parameters, extrarenal flare and adverse effects. RESULTS: A total of 215 patients were randomly allocated to the leflunomide group (n=108) and azathioprine group (n=107). Kidney flares were observed in 17 (15.7%) leflunomide-treated patients and 19 (17.8%) azathioprine-treated patients. Time to kidney flare did not statistically differ (leflunomide: 16 months vs azathioprine: 14 months, p=0.676). 24-hour proteinuria, serum creatinine, serum albumin, serum C3 and serum C4 improved similarly. Extrarenal flare occurred in two patients from the azathioprine group and one patient from the leflunomide group. The incidence of adverse events was similar in the 2 groups: leflunomide 56.5% and azathioprine 58.9%. CONCLUSIONS: The efficacy and safety profile of leflunomide are non-inferior to azathioprine for maintenance therapy of LN. Leflunomide may provide a new candidate for maintenance therapy in patients with LN. TRIAL REGISTRATION NUMBER: NCT01172002.

Glycine increased ferroptosis via SAM-mediated GPX4 promoter methylation in rheumatoid arthritis.

OBJECTIVE: Over-proliferation of synovium is a key event of invasive pannus formation and cartilage damage in the progression of RA disease. At the same time, ferroptosis may play a pivotal role in maintaining the balance of proliferation and death of synovium. In this study, we firstly evaluated the ferroptosis level in RA fibroblast-like synoviocytes (FLS) and then explored the role of glycine in ferroptosis. METHODS: Ferroptosis was evaluated in RA synovium and FLS. The therapeutic effect of glycine on RA was evaluated by clinical and histopathological score and cytokine level in a CIA mouse model. The influence of glycine on ferroptosis was evaluated by mitochondrial morphology observation and membrane potential assay in RA FLS. Methylase expression was detected to explore the mechanism behind the effect of glycine on glutathione peroxidase 4 (GPX4) methylation. RESULTS: Compared with healthy controls, ferroptosis decreased in the RA synovium and FLS, with a decrease in Acyl Coenzyme A Synthetase Long Chain 4 (ACSL4) and an increase in Ferritin heavy chain 1 (FTH1), GPX4 and cystine/glutamate antiporter solute carrier family 7 member 11 (SLC7A11). Although both oxidation and antioxidation levels of lipids were higher in RA FLS than in healthy controls, the increase in antioxidation was slightly higher than oxidation. RNA-seq and verification showed that glycine regulated the ferroptosis pathway through increase S-adenosylmethionine (SAM) concentration and decrease the expression of GPX4 and FTH1 by promoting SAM-mediated GPX4 promoter methylation and reducing FTH1 expression in RA FLS. CONCLUSIONS: In summary, we confirmed a decline in ferroptosis in RA and explored that glycine enhanced ferroptosis via SAM-mediated GPX4 promoter methylation and ferritin decrease.

Attaining treat-to-target endpoints with metformin in lupus patients: a pooled analysis.

OBJECTIVES: Low disease activity status and remission are crucial treat-to-target (T2T) endpoints in systemic lupus erythematosus (SLE). To evaluate the efficacy of metformin add-on in attaining T2T among Chinese patients with mild-to-moderate lupus, a post-hoc analysis combining our previous two randomised trials was carried out. METHODS: Data from the open-labeled proof-of-concept trial (ChiCTR-TRC-12002419) and placebo-controlled trial (NCT02741960) were integrated together. Disease flares were compared between patients attaining T2T or not at baseline. The efficacy of metformin versus placebo/nil add-on to standard therapy in SLE patients who did not meet the T2T criteria at baseline was evaluated in terms of attaining T2T at 12-month follow-up. RESULTS: Of 253 SLE patients, 43.8% (n=89) attained T2T at baseline. During the 12 months, 15 patients flared in the T2T group, which was significantly lower than that in the non-T2T group (16.9% vs. 36.0%, p=0.001). For 164 patients who did not meet the T2T criteria at entry, 59.0% and 43.6% of the 78 patients taking metformin in this population attained the lupus low disease activity status (LLDAS) and remission endpoints at last visit, respectively, as compared to 37.2% and 24.4% of the 86 patients in the placebo/nil group (LLDAS p=0.008; remission p=0.013). Over time, metformin helped patients achieving T2T earlier and maintain longer T2T duration over placebo/nil (LLDAS duration: 44.9% vs. 26.4%, p=0.002; remission duration:19.1% vs. 10.7%, p=0.014). CONCLUSIONS: This post-hoc analysis suggested that metformin might be an adjuvant therapy in achieving treat-to-target in SLE patients.

Salt-and-pepper appearance with supravenous pigment retention in systemic sclerosis.

We read with great interest a recent article in Clinical and Experimental Dermatology that found up to 40% of patients with systemic sclerosis and salt-and-pepper appearance had sparing of the skin folds and creases. Herein we present a case with pigment retention over the frontal branches of superficial temporal vessels, as an important complement to the 'sparing phenomenon' stated in the original paper.

Janus kinase inhibitor treatment improved both subcutaneous and pulmonary sarcoidosis in a patient with glaucoma.

This is the first case to provide significant evidence that JAK inhibitor is an effective treatment for both subcutaneous and pulmonary sarcoidosis, and it is also the first case in which tofacitinib was used in a patient who has a contraindication for corticosteroid therapy.

RIPK1 downregulation enhances neutrophil extracellular traps in psoriasis.

Introduction: Psoriasis is an immune-mediated systemic disease. Neutrophils are enriched in psoriasis lesions and can form neutrophil extracellular traps (NETs) to activate keratinocytes. Receptor-interacting protein kinase RIPK1 and RIPK3 are involved in necroptosis and NET formation. Aim: To elucidate whether RIPK1 regulates circulating neutrophils to form NETs and inflammation in psoriasis. Material and methods: Blood samples of psoriasis patients (n = 20) and healthy controls (n = 20) were detected by flow cytometry. The expression level of RIPK1/3 in isolated circulating neutrophils from psoriasis patients (n = 17) and healthy controls (n = 17) was examined by quantitative real-time PCR. SYTOX Green dye and PicoGreen reagent were used to detect NET formation and DNA release in neutrophils under the stimulation of phorbol 12-myristate 13-acetate (PMA) and necrostain-1 (Nec-1). Correlation analysis was performed between RIPK1/3 expression and Psoriasis Area Severity Index (PASI), neutrophil-to-lymphocyte ratio (NLR). Results: RIPK1 and RIPK3 expression in protein levels were decreased in monocytes and neutrophils from peripheral blood of psoriasis patients. In isolated psoriasis neutrophils, RIPK1 and Caspase8 mRNA were downregulated while RIPK3 and MLKL mRNA were elevated, leading to the necroptosis pathway. In addition, RIPK1-inhitor-necrostatin-1 (Nec-1) enhanced NETosis in psoriasis neutrophils in vitro. More importantly, there is a negative correlation between RIPK1 and psoriasis disease severity. Conclusions: Our data demonstrated that downregulated RIPK1 expression in psoriasis neutrophils may enhance NET generation. RIPK1 may be identified as a novel therapeutic target in psoriasis.

Lupus gut microbiota transplants cause autoimmunity and inflammation.

BACKGROUND: The etiology of systemic lupus erythematosus (SLE) is multifactorial. Recently, growing evidence suggests that the microbiota plays a role in SLE, yet whether gut microbiota participates in the development of SLE remains largely unknown. To investigate this issue, we carried out 16 s rDNA sequencing analyses in a cohort of 18 female un-treated active SLE patients and 7 female healthy controls, and performed fecal microbiota transplantation from patients and healthy controls to germ-free (GF) mice. RESULTS: Compared to the healthy controls, we found no significant different microbial diversity but some significantly different species in SLE patients including Turicibacter genus and other 5 species. Fecal transfer from SLE patients to GF mice caused GF mice to develop a series of lupus-like phenotypic features, including increased serum autoimmune antibodies, imbalanced cytokines, altered distribution of immune cells in mucosal and peripheral immune response, and upregulated expression of genes related to SLE in recipient mice that received SLE fecal microbiota transplantation (FMT). Moreover, the metabolism of histidine was significantly altered in GF mice treated with SLE patient feces, as compared to those which received healthy fecal transplants. CONCLUSIONS: Overall, our results describe a causal role of aberrant gut microbiota in contributing to the pathogenesis of SLE. The interplay of gut microbial and histidine metabolism may be one of the mechanisms intertwined with autoimmune activation in SLE.

Prognostic values of anti-Ro52 antibodies in anti-MDA5-positive clinically amyopathic dermatomyositis associated with interstitial lung disease.

OBJECTIVE: Anti-Ro52 antibody often co-occurs with anti-Jo1 antibody in antisynthetase syndrome and their co-occurrence correlates with a more aggressive clinical phenotype and poorer prognosis. The strong association of anti-Ro52 antibody with anti-melanoma differentiation-associated protein-5 (anti-MDA5) antibody has been indicated in juvenile myositis. The aim of this study was to assess the clinical significance of anti-Ro52 antibody in a cohort of adult patients with anti-MDA5-positive clinically amyopathic dermatomyositis with interstitial lung disease (CADM-ILD). METHODS: We assessed a cohort of 83 consecutive patients with anti-MDA5-positive CADM-ILD. Anti-MDA5 antibodies and anti-Ro52 antibodies were detected in immunoblotting and semi-quantitatively analysed by densitometry. Clinical features and the 24 month survival were compared between anti-MDA5-positive patients with and without anti-Ro52 antibodies. RESULTS: Anti-Ro52 antibodies were found in 74.7% of anti-MDA5-positive CADM-ILD patients and were associated with an increased frequency of rapidly progressive interstitial lung disease (RP-ILD; 54.8% vs 23.8%; P = 0.014) and cutaneous ulcerations (27.4% vs 4.8%; P = 0.033). The cumulative 24 month survival rate tended to be lower in patients with anti-Ro52 antibodies than patients without (59.9% vs 85.7%; P = 0.051). The combination of anti-Ro52 antibody status and anti-MDA5 antibody levels further stratified patients' survival rates, showing that the survival rate of patients who were dual positive for anti-MDA5 antibody and anti-Ro52 antibody was significantly lower than patients with mild positive anti-MDA5 antibody alone (59.9% vs 100%; P = 0.019). CONCLUSION: Anti-Ro52 antibody is highly prevalent in anti-MDA5-positive CADM-ILD patients and their coexistence correlates with a subgroup of patients with more aggressive phenotypes. The combination of anti-MDA5 antibody levels and anti-Ro52 antibody status could help to predict patients' prognosis and guide risk-based therapy.

Anti-Ro52 antibodies in clinical practice: A single-centre experience.

INTRODUCTIONS: To analyse the clinical significance of anti-Ro52 autoantibodies that target TRIM21 protein and occur in a variety of connective tissue diseases (CTD), 4782 cases with blood tested positive for anti-Ro52 antibodies between January 2016 and September 2017 in Drum Tower Hospital were enrolled. METHODS: Anti-Ro52 and anti-Ro60 were measured using the immunoblotting method together with antibodies against other extractable nuclear antigens at the time of the patient's first visit. RESULTS: In this cohort, females accounted for the majority of all subjects (75.9%) and the average age was 47.25 years old. About 97.4% were diagnosed as having various diseases, in which around 2/3 were CTDs. The incidence of CTD in patients with merely anti-Ro52 was lower than those with both anti-Ro52 and anti-Ro60 (54.7% vs 85.5% for all patients and 53.3% vs 87.1% for inpatients, both P < .0001). Amongst CTDs, the incidence of systemic lupus erythematosus was significantly decreased, while the incidence of inflammatory myositis as well as undifferentiated connective tissue diseases was increased in anti-Ro52 single-positive group. For patients with either CTDs or non-CTDs, respiratory involvement was more common in patients with merely anti-Ro52 (67.6% vs 34.7%, P < .0001 and 53.2% vs 36.3%, P < .01). Sub-analysis revealed that both interstitial lung disease and pulmonary infection were related to anti-Ro52 in CTD inpatients (P < .0001 and P < .05). CONCLUSIONS: Our study shows that anti-Ro52 could occur in various clinical conditions. These antibodies may appear in the early stage of CTD with the lung an important target organ, thus their presence warrants long-term follow-up.

Understanding Fibrosis in Systemic Sclerosis: Novel and Emerging Treatment Approaches.

PURPOSE OF THE REVIEW: Over the years, our perceptions of fibrogenesis in systemic sclerosis (SSc) have advanced a lot. Herein, we review potential targets for SSc discovered in the past 3 years. RECENT FINDINGS: In recent years, metabolites have come into the limelight of SSc research. Anti-oxidants, promotor of adipogenesis, modulator of fatty acid metabolism, regulator of glucose homeostasis, and adenosine deaminase open a new door for SSc treatment. A mosaic of biolipids, especially cannabinoid receptor 2 agonist, represents a rational therapeutic approach in fibrosis. In terms of immune aspects, targeting chemokines or integrins for cell adhesion may become new approach to inhibiting fibrotic pathways. Epigenetic modulation of immune pathways has been uncovered much recently. Targeting histone modifications and lncRNAs has demonstrated therapeutic potential in SSc animal models. The classical JAK-STAT and interferon pathway drive great attention these years because of the promising potential for the drug repurposing of targeted therapies from arthritis to SSc. In fibrosis-associated developmental pathways, BMP, Hedgehog, and PU.1 are expected to offer new targets to restrain fibrosis. New targets involved in metabolic reprogramming, immunity, epigenetics together with developmental and apoptotic pathways open new avenues for therapeutic modulation in SSc.

A Role for Receptor-Interacting Protein Kinase-1 in Neutrophil Extracellular Trap Formation in Patients with Systemic Lupus Erythematosus: a Preliminary Study.

BACKGROUND/AIMS: Neutrophil extracellular traps (NETs) are known to play an important role in systemic lupus erythematosus (SLE) by triggering innate and adaptive immune responses. The molecular mechanisms responsible for their formation in SLE are still unclear. In this study, we aim to characterize the role of the receptor-interacting protein kinase-1 (RIPK1), a homologous serine/threonine kinase previously implicated in the regulation of necroptosis and tissue injury, in decreasing neutrophil death and formation of NETs, and to investigate the clinical implications of RIPK1 in SLE. METHODS: Patients with SLE (n = 50) and healthy donors (n = 35) were enrolled in in vitro studies. Management of SLE patients was evaluated using the SLE disease activity index 2000 (SLEDAI-2K) score and laboratory variables. The mRNA level of RIPKs was measured by quantitative polymerase chain reaction (qPCR). Intracellular RIPK1 and RIPK3 production by peripheral blood leukocytes was detected by four-color flow cytometry and confirmed by automatic western blotting. TNF-α, IFN-γ, IL-1ß, IL-2, IL-8, IL-18, and RIPK1 were measured by enzyme-linked immunosorbent assay. Cell death was assayed by Sytox green dye from peripheral neutrophils stimulated by RIPK-1-stabilizer necrostatin-1 (nec-1) and phorbol 12-myristate 13-acetate (PMA). Immunofluorescence staining and confocal microscopy were used to detect NET formation ex vivo. Quantification of NETs was determined by fluorescence spectrometry. RESULTS: IFN-γ, IL-1ß, IL-8, and IL-18 levels in serum were increased in SLE patients compared to controls. However, the expression of TNF-α, IL-2, and RIPK1 were decreased. In addition, we observed significant differences in the expression of RIPK1 in peripheral blood leukocytes. Of all the leukocytes, RIPK1 expression was significantly lower in neutrophils. Furthermore, we studied NETs formation in neutrophils of SLE with decreased RIPK1 expression, and these show increased susceptibility to NETosis, when stimulated with PMA and/or nec-1. Importantly, RIPK1 expression in neutrophils negatively correlated with ESR, CRP, 24-hour urine total protein, and the disease activity index in SLE. CONCLUSION: These data represent the first report of decreased RIPK1 expression in neutrophils of SLE patients and imply that RIPK1 may be involved in neutrophil death and NET formation. We suggest that RIPK1 is a potential biomarker to predict disease activity.