Follistatin-like protein 1 (FSTL1) is a proinflammation mediator implicated in arthritis in rodent animal models. The present study is aimed at assessing FSTL1 levels in systemic autoimmune diseases and correlating them with disease activity in patients with rheumatoid arthritis (RA). Serum FSTL1 levels from 487 patients with systemic autoimmune diseases and 69 healthy individuals were measured by enzyme-linked immunosorbent assay (ELISA). FSTL1 expression in synovial fluid (SF) and synovial tissues (STs) was determined by ELISA, immunohistochemistry, real-time polymerase chain reaction (RT-PCR) and western blot analysis in RA patients and trauma controls. FSTL1 levels in fibroblast-like synoviocytes (FLSs) from RA patients were determined by real-time PCR and western blot analysis. Serum FSTL1 levels were significantly elevated in patients with RA, ulcerative colitis, systemic lupus erythematosus, Sjögren's syndrome (SS), systemic sclerosis and polymyositis/dermatomyositis. Serum FSTL1 levels in the RA and secondary SS patients were substantially higher than those in other patients. Serum FSTL1 levels were increased in early RA, rheumatoid factor (RF)- and anti-cyclic citrullinated peptide antibody (ACPA)-negative patients compared to healthy controls. Moreover, serum FSTL1 concentrations were significantly higher in long-standing RA patients than in early RA patients and in the RF- and ACPA-positive RA patients than in RF- and ACPA-negative RA patients. Elevated FSTL1 levels in the STs and SF of RA patients were also observed. FSTL1 levels in serum were markedly higher than those in SF in RA patients. The strongest FSTL1 staining was detected in the cytoplasm of synovial and capillary endothelial cells from RA synovium. Furthermore, FSTL1 was induced in FLSs by inflammatory mediators. Importantly, serum FSTL1 levels were correlated with several important biologic and clinical markers of disease activity, including erythrocyte sedimentation rate, C-reactive protein, RF, ACPA, swollen joint count, patient global visual analogue scale score and Disease Activity Score 28 in the adult RA patient population. Notably, serum FSTL1 levels were significantly diminished following successful treatment and clinical improvement. Elevated FSTL1 levels reflect not only joint diseases but also inflammation and tissue degradation in systemic autoimmune diseases. Serum FSTL1 levels may thus serve as a serological inflammatory marker of disease activity in RA patients.

Microplastics (MPs) are defined as plastic particles smaller than 5 mm in size, and nanoplastics (NPs) are those MPs with a particle size of less than 1000 nm or 100 nm. The prevalence of MPs in the environment and human tissues has raised concerns about their potential negative effects on human health. Macrophages are the major defence against foreign substances in the intestine, and can be polarized into two types: the M1 phenotype and the M2 phenotype. However, the effect of NPs on the polarization of macrophages remains unclear. Herein, we selected polystyrene, one of the most plastics in the environment and controlled the particle sizes at 50 nm and 500 nm respectively to study the effects on the polarization of macrophages. We used mouse RAW264.7 cell line models in this macrophage-associated study. Experiments on cell absorption showed that macrophages could quickly ingest polystyrene nanoplastics of both diameters with time-dependent uptake. Compared to the untreated group and 10 μg/mL treatment group, macrophages exposed to 50 μg/mL groups (50 nm and 500 nm) had considerably higher levels of CD86, iNOS, and TNF-α, but decreased levels of aCD206, IL-10, and Arg-1. According to these findings, macrophage M1 and M2 polarization can both be induced and inhibited by 50 μg/mL 50 nm and 500 nm polystyrene nanoplastics. This work provided the first evidence of a possible MPs mode of action with appropriate concentration and size through the production of polarized M1, providing dietary and environmental recommendations for people, particularly those with autoimmune and autoinflammatory illnesses.

CD4+CD28− T cells exhibit autoreactive potential in autoimmune disorders, including rheumatoid arthritis (RA). It is not well known which costimulator functions as an alternative second signal in the activation of this subset after CD28 expression is downregulated. Tumor necrosis factor receptor superfamily member OX40 is a key costimulator in the activation of T cells. The aim of this study was to investigate the costimulatory effects of OX40 on CD4+CD28− T cells in autoimmune arthritis. Clinical samples were collected from patients with RA and control subjects. Collagen-induced arthritis (CIA) was induced with collagen type II (CII) in DBA/1 mice. The CD4+CD28−OX40+ T-cell subset and its cytokine production were detected by flow cytometry. After T-cell purification, adoptive transfer was performed in CIA mice. The regulatory role of OX40 was determined by blocking experiments in vitro and in vivo. OX40 and OX40L were abnormally expressed in patients with RA and CIA mice. Further analysis showed that CD4+CD28−OX40+ T cells accumulated in patients with RA and in animal models. These cells produced higher levels of proinflammatory cytokines and were closely correlated with the clinicopathological features of the affected individuals. Adoptive transfer of CII-specific CD4+CD28−OX40+ T cells remarkably aggravated arthritic development and joint pathology in CIA mice. Moreover, OX40 blockade significantly reduced the proinflammatory responses and ameliorated arthritis development. OX40 acts as an alternative costimulator of CD4+CD28− T cells and plays a pathogenic role in autoimmune arthritic development, suggesting that it is a potential target for immunomodulatory therapy of RA.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease involving multiple organs. It is often called “immortal cancer” due to the difficulties in disease treatment. As the cornerstone of immune regulation, the programmed cell death protein 1 (PD-1) has been extensively studied in the context of chronic inflammation due to its ability of regulating immune response and immunosuppression. Recently, more and more studies on rheumatic immune related complications have also focused on PD-1 and proposed that the use of PD-1 agonist could inhibit the activation of lymphocytes and alleviate SLE disease activity. In this review, we summarized the role of PD-1 in SLE, implicating its potential application as a biomarker to predict SLE disease activity; we also proposed that the combination of PD-1 agonist and low-dose IL-2 may have better therapeutic efficacy, shining light on a new direction for developing specific treatment approaches.

Rationale: Thrombotic thrombocytopenic purpura (TTP) is a rare, fatal disorder which could be caused by autoimmune diseases. However, TTP secondary to Sjögren syndrome (SS) is extremely rare. Patient concerns: A 47-year- old woman with an 8-year history of SS was admitted due to skin ecchymosis and bleeding gums. Then she gradually developed fever and headache. Diagnoses: Laboratory investigations suggested anemia, thrombocytopenia, increased lactic dehydrogenase, and a disintegrin-like metalloproteinase with thrombospondin motif type 1 member 13 (ADAMTS13) activity deficiency with high inhibitor titers. Acquired TTP was thus diagnosed. Interventions: Plasma exchange (PE) was the first choice for treatment, while glucocorticoid, cyclosporine A (CSA), rituximab, and intravenous immunoglobulin (IVIG) were used simultaneously. Bortezomib, a selective proteasome inhibitor and thereby inducing apoptosis in both B-cells and plasma cells, was added. Outcomes: She was discharged from the hospital and then treated with prednisone of 40 mg/d and hydroxychloroquine. The patient remained in full remission. Lessons: We conclude that bortezomib should be considered for patients with TTP refractory to PE, steroids, and rituximab due to its efficacy and relatively favorable side effect profile.

To explore the etiology of risk factors and quantify the mortality differences in systemic lupus erythematosus (SLE) patients with different initial disease activity. The Jiangsu Lupus database was established by collecting medical records from first-hospitalized SLE patients during 1999–2009 from 26 centers in Jiangsu province, China, and their survival status every five years. The initial SLEDAI scores [high (>12) vs. low–moderate (≤12)] differences in mortality attributable to risk factors were quantified using population attributable fraction (PAF), relative attributable risk (RAR) and adjusted relative risk (ARR). Among 2446 SLE patients, 83 and 176 deaths were observed in the low–moderate and high activity groups, with mortality rates of 7.7 and 14.0 per 1000 person years, respectively. Anemia was the leading contributor to mortality, with PAFs of 40.4 and 37.5 in the low–moderate and high activity groups, respectively, and explained 23.2% of the mortality differences with an ARR of 1.66 between the two groups. Cardiopulmonary involvement caused the highest PAFs in the low–moderate (20.5%) and high activity (13.6%) groups, explaining 18.3% of the mortality differences. The combination of anemia and cardiopulmonary involvement had the highest RAR, causing 39.8% of the mortality differences (ARR = 1.52) between the two groups. In addition, hypoalbuminemia and a decrease in the creatinine clearance rate accounted for 20–30% of deaths and explained 10–20% of the mortality differences between the two groups, while antimalarial drug nonuse accounted for about 35% of deaths and explained 3.6% of the mortality differences. Anemia, cardiopulmonary involvement and hypoalbuminemia may cause substantial mortality differences across disease activity states, suggesting additional strategies beyond disease activity assessment to monitor SLE outcomes.