Hypoxia-Inducible Factor-2 Alpha Regulates the Migration of Fibroblast-like Synoviocytes via Oxidative Stress-Induced CD70 Expression in Patients with Rheumatoid Arthritis.

This study aimed to examine the role of CD70, which is highly expressed on fibroblast-like synoviocytes (FLS), in rheumatoid arthritis (RA) patients. FLS isolated from RA (n = 14) and osteoarthritis (OA, n = 4) patients were stimulated with recombinant interleukin-17 (IL-17; 5 ng/mL) and tumor necrosis factor alpha (TNF-α; 5 ng/mL) for 24 h. Expression of CD70, CD27/soluble CD27 (sCD27), and hypoxia-inducible factor-2 alpha (HIF-2α) was analyzed by RT-qPCR, flow cytometry, and ELISA assays, respectively. Reactive oxygen species (ROS) expression and cell migration were also examined. The HIF-2α inhibitor PT-2385 and CD70 inhibitor BU69 were used to specifically suppress these pathways. Stimulation with IL-17 and TNF-α significantly induced CD70 expression in RA FLS. Although the synovial fluids from patients with RA contained high levels of sCD27, surface expression of CD27, a ligand of CD70, was rarely detected in RA FLS. Cytokine-induced CD70 expression was significantly decreased following antioxidant treatment. Following HIF-2α inhibition, RA FLS had decreased expression of CD70 and ROS levels. Migration of RA FLS was also inhibited by inhibition of CD70 or HIF-2α. The surface expression of CD70 is regulated by HIF-2α and ROS levels and is a key contributor to cytokine-enhanced migration in RA FLS.

Elevated APE1/Ref-1 Levels of Synovial Fluids in Patients with Rheumatoid Arthritis: Reflection of Disease Activity.

There is growing evidence that apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) regulates inflammatory responses. Rheumatoid arthritis (RA) is an autoimmune disease, which is characterized with synovitis and joint destruction. Therefore, this study was planned to investigate the relationship between APE1/Ref-1 and RA. Serum and synovial fluid (SF) were collected from 46 patients with RA, 45 patients with osteoarthritis (OA), and 30 healthy control (HC) patients. The concentration of APE1/Ref-1 in serum or SF was measured using the sandwich enzyme-linked immunosorbent assay (ELISA). The disease activity in RA patients was measured using the 28-joint disease activity score (DAS28). The serum APE1/Ref-1 levels in RA patients were significantly increased compared to HC and OA patients (0.44 ± 0.39 ng/mL for RA group vs. 0.19 ± 0.14 ng/mL for HC group, p < 0.05 and vs. 0.19 ± 0.11 ng/mL for OA group, p < 0.05). Likewise, the APE1/Ref-1 levels of SF in RA patients were also significantly increased compared to OA patients (0.68 ± 0.30 ng/mL for RA group vs. 0.31 ± 0.12 ng/mL for OA group, p < 0.001). The APE1/Ref-1 concentration in SF of RA patients was positively correlated with DAS28. Thus, APE1/Ref-1 may reflect the joint inflammation and be associated with disease activity in RA.

Reduction of Oxidative Stress in Peripheral Blood Mononuclear Cells Attenuates the Inflammatory Response of Fibroblast-like Synoviocytes in Rheumatoid Arthritis.

The production and oxidation mechanism of reactive oxygen species (ROS) are out of balance in rheumatoid arthritis (RA). However, the correlation between ROS and T cell subsets in RA remains unclear. Peripheral blood mononuclear cells (PBMCs) from patients with RA (n = 40) and healthy controls (n = 10) were isolated from whole blood samples. Synovial tissues (n = 3) and synovial fluid (n = 10) were obtained from patients with RA. The repartition of T cell subsets and expression of ROS and cytokines were examined according to RA severity. Fibroblast-like synoviocytes (FLSs) from patients with RA were stimulated with PBMCs and the expression of inflammation-related molecules were measured by RT-PCR and cytokine array. Regulatory T cells from patients with moderate (5.1 > DAS28 ≥ 3.2) RA showed the highest expression of mitochondrial ROS among the groups based on disease severity. Although ROS levels steadily increased with RA severity, there was a slight decline in severe RA (DAS28 ≥ 5.1) compared with moderate RA. The expression of inflammatory cytokines in RA FLSs were significantly inhibited when FLSs were co-cultured with PBMCs treated with ROS inhibitor. These findings provide a novel approach to suppress inflammatory response of FLSs through ROS regulation in PBMCs.

Association between body mass index and fragility fracture in postmenopausal women: a cross-sectional study using Korean National Health and Nutrition Examination Survey 2008-2009 (KNHANES IV).

BACKGROUND: The present study examined the relationship between body mass index (BMI) and the risk for fragility fractures in postmenopausal Korean women. METHODS: Among subjects who participated in the 4th Korea National Health and Nutrition Examination Survey (2008-2009), 2114 women ≥ 40 years of age were included. BMI was based on standards set by the Korean Society for the Study of Obesity, as follows: < 18.5 kg/m2, underweight; 18.5 ≤ to < 25 kg/m2, normal weight; and ≥ 25 kg/m2, obese. Subjects were also divided into three groups according to the location of fragility fracture: spine, hip, or wrist. RESULTS: The mean (± SD) rate of fragility fracture was significantly different among the three groups: 5.9 ± 2.9% (underweight), 1.1 ± 0.3% (normal weight), and 3.0 ± 0.7% (obese) (p = 0.001). After correcting for age, family history, and treatment history of osteoporosis and rheumatoid arthritis, smoking and drinking status, and level of exercise, multivariable regression analysis revealed that the odds ratio for fragility fracture in the underweight group was 5.48 [95% confidence interval (CI) 1.80-16.73] and 3.33 (95% CI 1.61-6.87) in the obese group. After subdividing fragility fractures into vertebral and non-vertebral, the odds ratio for vertebral fracture in the underweight group was 5.49 (95% CI 1.31-23.09) times higher than that in the normal weight group; in the obese group, the non-vertebral fracture odds ratio was 3.87 (95% CI 1.45-10.33) times higher. Analysis of non-vertebral fractures in the obese group revealed an odds ratio for fracture 22.05 (95% CI 1.33-365.31) times higher for hip fracture and 3.85 (95% CI 1.35-10.93) times higher for wrist fracture. CONCLUSIONS: Obesity and underweight increased the risk for fragility fractures in postmenopausal Korean women.

The effect of nicotinamide adenine dinucleotide phosphate oxidase 4 on migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis.

BACKGROUND: Reactive oxygen species (ROS) regulate the migration and invasion of fibroblast-like synoviocytes (FLS), which are key effector cells in rheumatoid arthritis (RA) pathogenesis. Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) induces ROS generation and, consequently, enhances cell migration. Despite the important interrelationship between RA, FLS, and ROS, the effect of NOX4 on RA pathogenesis remains unclear. METHODS: FLS isolated from RA (n = 5) and osteoarthritis (OA, n = 5) patients were stimulated with recombinant interleukin 17 (IL-17; 10 ng/ml) and tumor necrosis factor alpha (TNF-α; 10 ng/ml) for 1 h. Cell migration, invasion, adhesion molecule expression, vascular endothelial growth factor (VEGF) secretion, and ROS expression were examined. The mRNA and protein levels of NOX4 were analyzed by RT-qPCR and western blotting, respectively. The NOX4 inhibitor GLX351322 and NOX4 siRNA were used to inhibit NOX4 to probe the effect of NOX4 on these cellular processes. RESULTS: Migration of RA FLS was increased 2.48-fold after stimulation with IL-17 and TNF-α, while no difference was observed for OA FLS. ROS expression increased in parallel with invasiveness of FLS following cytokine stimulation. When the expression of NOX was examined, NOX4 was significantly increased by 9.73-fold in RA FLS compared to unstimulated FLS. Following NOX4 inhibition, cytokine-induced vascular cell adhesion molecule 1 (VCAM1), VEGF, and migration and invasion capacity of RA FLS were markedly decreased to unstimulated levels. CONCLUSION: NOX4 is a key contributor to cytokine-enhanced migration and invasion via modulation of ROS, VCAM1, and VEGF in RA FLS.

Relationship between alcohol consumption and rheumatoid factor (RF) with alcohol-induced facial flushing response.

This study investigated the relationship between alcohol consumption with alcohol-induced facial flushing response and rheumatoid factor (RF) in adult men. The cohort comprised 1675 men who underwent a general medical check-up between July 2016 and June 2017, including 355 non-drinkers, 498 flushers, and 822 non-flushers. One drink was defined as 14 g of alcohol. RF was considered negative if the level was less than 18 IU/mL and positive if the level was greater than 18 IU/mL. Logistic regression analyses were used. Compared to non-drinkers, the odds ratio for a positive RF among non-flushers was 0.92 (95% confidence interval [CI], 0.37-2.29) for those with an average alcohol consumption of ≤4 drinks per week, 1.64 (95% CI, 0.67-3.98) for those consuming more than 4 drinks per week but fewer than or equal to 8 drinks per week, and 1.17 (95% CI, 0.55-2.50) for those consuming more than 8 drinks per week; the differences were not statistically significant. Compared to non-drinkers, flushers also had a non-significant odds ratio for positive RF of 1.26 (95% CI, 0.54-2.90) among those with an average alcohol consumption of ≤4 drinks per week. However, flushers showed a significantly higher odds ratio for a positive RF of 3.12 (95% CI, 1.18-8.24) among those consuming more than 4 but fewer than or equal to 8 drinks per week, and 3.27 (95% CI, 1.42-7.52) among those consuming more than 8 drinks per week. Additionally, flushers consuming more than 8 drinks per week were associated with significantly higher rates of positive RF than non-flushers (odds ratio, 2.38; 95% CI, 1.05-5.17). Our study revealed that flushers consuming more than 4 drinks per week showed a higher probability of positive RF than non-drinkers. Furthermore, flushers consuming more than 8 drinks per week had a higher probability of positive RF than non-flushers. Our results strongly indicate that the average weekly alcohol consumption level and the presence or absence of flushing should be considered when interpreting the results of RF examinations in healthy men.

Serum and synovial fluid concentrations of cold-inducible RNA-binding protein in patients with rheumatoid arthritis.

AIM: There is growing evidence that cold-inducible RNA-binding protein (CIRP) promotes inflammatory responses. This study investigated the relationship between CIRP and rheumatoid arthritis (RA). METHODS: Peripheral blood and synovial fluid were collected from 15 patients with RA and from 16 patients with osteoarthritis (OA). The concentration of CIRP was measured with the sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: The concentration of serum CIRP was significantly elevated in the RA patient group (RA patients = 26.39 ± 10.48 pg/mL, OA patients = 17.14 ± 7.24 pg/mL, P = 0.009). Furthermore, the RA patient group had a significantly higher CIRP concentration than that of the OA patient group in synovial fluid (153.56 ± 108.93 pg/mL vs. 23.63 ± 16.18 pg/mL, P < 0.001). The mean synovial fluid concentration of CIRP was significantly higher than that of the serum concentration in the RA patient group (serum concentration = 26.39 ± 10.48 pg/mL, synovial fluid = 153.56 ± 108.93 pg/mL, P < 0.001). Disease Activity Score of 28 joints (DAS28)-ESR (erythrocyte sedimentation rate) and DAS28-CRP (C-reactive protein) were positively correlated with the synovial fluid concentration of CIRP (DAS28-ESR: r = 0.582, P = 0.023; DAS28-CRP: r = 0.541, P = 0.037). CONCLUSION: The serum and synovial concentrations of CIRP in the RA patients were increased compared to the OA patients. Additionally, the synovial concentration of CIRP in RA patients correlated well with disease activity, that is, the DAS28-ESR/CRP. Based on these results, CIRP mediates inflammation and is a potential marker for synovial inflammation.