TNF antagonist sensitizes synovial fibroblasts to ferroptotic cell death in collagen-induced arthritis mouse models.

Ferroptosis is a nonapoptotic cell death process that requires cellular iron and the accumulation of lipid peroxides. In progressive rheumatoid arthritis (RA), synovial fibroblasts proliferate abnormally in the presence of reactive oxygen species (ROS) and elevated lipid oxidation. Here we show, using a collagen-induced arthritis (CIA) mouse model, that imidazole ketone erastin (IKE), a ferroptosis inducer, decreases fibroblast numbers in the synovium. Data from single-cell RNA sequencing further identify two groups of fibroblasts that have distinct susceptibility to IKE-induced ferroptosis, with the ferroptosis-resistant fibroblasts associated with an increased TNF-related transcriptome. Mechanistically, TNF signaling promotes cystine uptake and biosynthesis of glutathione (GSH) to protect fibroblasts from ferroptosis. Lastly, low dose IKE together with etanercept, a TNF antagonist, induce ferroptosis in fibroblasts and attenuate arthritis progression in the CIA model. Our results thus imply that the combination of TNF inhibitors and ferroptosis inducers may serve as a potential candidate for RA therapy.

Anti-Aging Effect of Chitosan Oligosaccharide on d-Galactose-Induced Subacute Aging in Mice.

Chitosan oligosaccharide (COS), a natural polysaccharide with good antioxidant and anti-inflammatory properties, is the depolymerized product of chitosan possessing various biological activities. The present study was designed to investigate the possible anti-aging effect of COS on the aging model mouse induced by d-galactose (d-gal) and explore the underlying mechanism. In the experiment, 48 male Kunming mice (KM mice) were randomly divided into the normal group, model group, positive group, and low-medium-high dose polysaccharide groups (300, 600, 1200 mg/kg/day). The results showed that COS, by intragastric gavage after subcutaneous injection of d-gal (250 mg/kg/day) into the neck of mice consecutively for eight weeks, gradually recovered the body weight, the activity of daily living, and organ indices of mice, as well as effectively ameliorated the histological deterioration of the liver and kidney in mice triggered by d-gal. To be specific, COS obviously improved the activities of antioxidant enzymes in liver and kidney of KM mice, including catalase (CAT), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD), as well as decreased malondialdehyde (MDA) levels when compared with those in model group mice. Furthermore, COS not only elevated the diminished levels of serum immunoglobulin G (IgG) and IgM induced by d-gal, but also significantly inhibited the d-gal-caused upregulation of serum alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), uric acid (UA) and creatinine (CREA) levels as compared with those of mice in the model group. These results demonstrate that COS has an obvious anti-aging activity in d-gal-induced subacute aging mice, the mechanism of which, to some extent, is associated with enhancing the antioxidant defenses, reducing oxidative stress, and improving the immune function of aging model mice.

High prevalence of hypovitaminosis D of patients with autoimmune rheumatic diseases in China.

We aimed to determine the prevalence of hypovitaminosis D in patients with autoimmune rheumatic diseases (ARDs) in China and its association with demographic characteristics of the patients. We recruited 384 patients in this cross-sectional study including 121 cases of systemic lupus erythematosus (SLE), 131 rheumatoid arthritis (RA), 102 spondyloarthritis (SpA) and 30 other ARDs. For each patient, demographic information was collected and serum concentration of 25OHD3 was measured by electrochemiluminescence immunoassay (ECLIA). The multivariate logistic regression model was used to investigate the association between vitamin D deficiency and patient characteristics. The mean serum vitamin D level of the 384 patients was 18.91 (8.12) ng/mL, and the median age was 37.33 (12.01) yrs. Among these patients, 222 (57.81%) and 127 (33.07%) were found to be vitamin D deficiency and insufficiency, respectively. From the disease perspective, the percentages of insufficiency and deficiency were as follow: 97.52% and 84.30% in SLE, 87.02% and 48.85% in RA, 88.24% and 40.20% in SpA, 90.89% and 57.81% in other ARDs patients. The causative factors for vitamin D deficiency included SLE per se (OR 12.54, P < 0.001) and high body mass index (BMI) (OR 1.88, P < 0.001). However, the seniors were less likely to have vitamin D deficiency (OR 0.95, P = 0.005). No correlation was disclosed between vitamin D deficiency and gender or disease duration. Hypovitaminosis D is highly prevalent among autoimmune rheumatic diseases population in China. The SLE per se and the obesity are the risk factors for vitamin D deficiency. Clinicians are advised to supplement vitamin D in these patients.