Adipocytokines in Untreated Newly Diagnosed Rheumatoid Arthritis: Association with Circulating Chemokines and Markers of Inflammation

Adipokines in Rheumatoid Arthritis: Emerging Biomarkers and Therapeutic Targets

Rheumatoid arthritis (RA) is a chronic inflammatory disease manifested by joint involvement, extra-articular manifestations, and general symptoms. Adipose tissue, previously perceived as an inert energy storage organ, has been recognised as a significant contributor to RA pathophysiology. Adipokines modulate immune responses, inflammation, and metabolic pathways in RA. Although most adipokines have a pro-inflammatory and aggravating effect on RA, some could counteract this pathological process. The coexistence of RA and sarcopenic obesity (SO) has gained attention due to its impact on disease severity and outcomes. Sarcopenic obesity further contributes to the inflammatory milieu and metabolic disturbances. Recent research has highlighted the intricate crosstalk between adipose tissue and skeletal muscle, suggesting potential interactions between these tissues in RA. This review summarizes the roles of adipokines in RA, particularly in inflammation, immune modulation, and joint destruction. In addition, it explores the emerging role of adipomyokines, specifically irisin and myostatin, in the pathogenesis of RA and their potential as therapeutic targets. We discuss the therapeutic implications of targeting adipokines and adipomyokines in RA management and highlight the challenges and future directions for research in this field.

Adipokines and risk of rheumatoid arthritis: A two-sample multivariable Mendelian randomisation study

Adiponectin, leptin, and resistin are thought to be involved in the pathogenesis of rheumatoid arthritis (RA). However, the causal relationship between these adipokines and the risk for RA is unclear. We performed a range of two-sample Mendelian randomisation (MR) analyses to assess the causal effect of circulating adiponectin, leptin, and resistin on RA risk in European and East Asian individuals. Different sets of adiponectin-, leptin-, and resistin-related genetic variants were used as instruments for genetically determined adipokine levels. As body mass index (BMI) is a risk factor for RA and affects adipokine levels, multivariable MR was used to calculate the causal effect of each adipokine on RA risk taking BMI into account. Several MR analyses revealed no evidence of a causal relationship between circulating adiponectin, leptin, or resistin levels and RA risk in either Europeans or East Asians. Similarly, multivariable MR did not provide evidence of any causal effect of adiponectin, leptin, or resistin on RA risk when taking BMI into account. This MR study shows for the first time that genetically determined levels of adiponectin, leptin, or resistin do not have a direct causal effect on the risk of developing RA after adjustment for BMI.

Inhibition of NUCB2 suppresses the proliferation, migration, and invasion of rheumatoid arthritis synovial fibroblasts from patients with rheumatoid arthritis in vitro

Rheumatoid arthritis (RA) is an autoimmune polyarthritis in which synovial fibroblasts (SF) play a major role in cartilage and bone destruction through tumorlike proliferation, migration, and invasion. Nesfatin-1, an 82-amino-acid-long peptide discovered by Oh-I in 2006, is derived from the precursor protein nucleobindin-2 (NUCB2). NUCB2/nesfatin-1 promotes cell proliferation, migration, and invasion in various tumors. We have previously shown that increased nesfatin-1 levels in the synovium may be associated with disease severity in patients with RA. However, the effect of NUCB2 on the tumorlike transformation of RASF has not yet been reported. The expression of NUCB2 mRNA in the synovium of RA and non-RA patients was further confirmed using three individual datasets from the NCBI GEO database. Gene set enrichment analysis (GSEA) was employed to explore the association between NUCB2 mRNA and RA-related gene signatures or signaling pathways in the GSE77298 dataset. Cell proliferation, migration, and invasion abilities were determined using Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), wound healing, and transwell assays, respectively. The results showed that the levels of NUCB2 mRNA in the synovium were significantly elevated in patients with RA. Moreover, GSEA showed that high expression of NUCB2 mRNA was related to gene signatures, including those involved in the cell cycle, DNA replication, extracellular matrix-receptor interaction, and focal adhesion. Furthermore, the results of CCK-8 and EdU assays indicated that inhibition of NUCB2 markedly repressed RASF proliferation. Additionally, the results of wound healing and transwell assays demonstrated that inhibition of NUCB2 significantly suppressed the migratory and invasive abilities of RASFs. Our findings are the first to demonstrate that the inhibition of NUCB2 suppresses the proliferation, migration, and invasion of RASFs in vitro.

Adipokines as targets in musculoskeletal immune and inflammatory diseases

Adipokines are the principal mediators in adipose signaling. Nevertheless, besides their role in energy storage, these molecules can be produced by other cells, such as immune cells or chondrocytes. Given their pleiotropic effects, research over the past few years has also focused on musculoskeletal diseases, showing that these adipokines might have relevant roles in worsening the disease or improving the treatment response. In this review, we summarize recent advances in our understanding of adipokines and their role in the most prevalent musculoskeletal immune and inflammatory disorders.

Fecal microbiota of adolescent and young adult cancer survivors and metabolic syndrome: an exploratory study

Metabolic syndrome and obesity occur commonly in long-term pediatric cancer survivors. The intestinal microbiome is associated with metabolic syndrome and obesity in the general population, and is perturbed during cancer therapy. We aimed to determine if long-term survivors of pediatric cancer would have reduced bacterial microbiome diversity, and if these findings would be associated with components of the metabolic syndrome, obesity, and chronic inflammation. We performed a cross-sectional exploratory study examining the intestinal microbiome via 16S amplicon sequencing, treatment history, clinical measurements (blood pressure, body mass index) and biomarkers (hemoglobin A1c, lipoproteins, adiponectin: leptin ratio, C-reactive protein, TNFα, Interleukin-6, and Interleukin-10) between 35 long-term survivors and 32 age, sex, and race matched controls. All subjects were aged 10-40 years, and survivors were at least five years from therapy completion. Survivors had lower alpha diversity compared to controls (Shannon index p = .001, Simpson index p = .032) and differently abundant bacterial taxa. Further, among survivors, those who received radiation (18/35) to the central nervous system or abdomen/pelvis had decreased alpha diversity compared to those who did not receive radiation (Shannon and Simpson p < .05 for both). Although, no specific component of metabolic syndrome or cytokine was associated with measures of alpha diversity, survivors with low adiponectin-lectin ratio, elevated body mass index, and elevated C-reactive protein had differently abundant taxa compared to those with normal measures. The microbiome of cancer survivors remains less diverse than controls even many years after diagnosis, and exposure to radiation may lead to further loss of diversity in survivors.Supplemental data for this article is available online at https://doi.org/10.1080/08880018.2022.2049937.

Adiponectin Is a Component of the Inflammatory Cascade in Rheumatoid Arthritis

Adiponectin is a secretory protein of adipocytes that plays an important role in pathological processes by participation in modulating the immune and inflammatory responses. The pro-inflammatory effect of adiponectin is observed in rheumatoid arthritis (RA). In this study, we examined adiponectin plasma levels and the expression of adiponectin in bone marrow tissue samples, synovium samples, and infrapatellar fat pad samples from patients with osteoarthritis (OA) and RA. Additionally we examined the expression of adiponectin receptors AdipoR1 and AdipoR2 in synovium samples and infrapatellar fat pad samples from patients with OA and RA. We also assessed the correlations between adiponectin plasma concentrations, adiponectin expression in bone marrow, synovium, infrapatellar fat pad, and plasma levels of selected cytokines. We found increased expression of adiponectin in synovium samples and infrapatellar fat pad samples from patients with RA as compared to patients with OA. There were no statistically significant differences of adiponectin plasma levels and adiponectin expression in bone marrow tissue samples between OA and RA patients. There were no differences in the expression of AdipoR1 and AdipoR2 at the mRNA level in synovial tissue and the infrapatellar fat pad between RA and OA patients. However, in immunohistochemical analysis in samples of the synovial membrane from RA patients, we observed very strong expression of adiponectin in intima cells, macrophages, and subintimal fibroblasts, such as synoviocytes, vs. strong expression in OA samples. Very strong expression of adiponectin was also noted in adipocytes of Hoffa’s fat pad of RA patients. Expression of AdipoR1 was stronger in RA tissue samples, while AdipoR2 expression was very similar in both RA and OA samples. Our results showed increased adiponectin expression in the synovial membrane and Hoffa’s pad in RA patients compared to that of OA patients. However, there were no differences in plasma adiponectin concentrations and its expression in bone marrow. The results suggest that adiponectin is a component of the inflammatory cascade that is present in RA. Pro-inflammatory factors enhance the expression of adiponectin, especially in joint tissues—the synovial membrane and Hoffa’s fat pad. In turn, adiponectin also increases the expression of further pro-inflammatory mediators.

Adiponectin is negatively associated with disease activity and Sharp score in treatment-naïve Han Chinese rheumatoid arthritis patients

The association and potential role of the protein hormone adiponectin in autoimmune diseases causing musculoskeletal disorders, including rheumatoid arthritis (RA), are controversial. Conflicting results may arise from the influences of confounding factors linked to genetic backgrounds, disease stage, disease-modifying anti-rheumatic drugs and patients' metabolic characteristics. Here, we examined serum level of adiponectin and its relationship with disease activity score 28 with erythrocytes sedimentation rate (DAS28[ESR]) and Sharp score in a treatment-naïve Han Chinese RA population. This cross-sectional study enrolled 125 RA patients. Serum level of total adiponectin was assessed by enzyme-linked immunosorbent assay (ELISA). Other important clinical and laboratory parameters were collected from the hospital database. DAS28(ESR) was calculated according to the equation previously published. Sharp score was evaluated based on hands radiographs by an independent radiologist. The correlation between serum adiponectin level and DAS28(ESR) or the Sharp score was investigated by univariate and multivariable linear regression analyses, respectively. Multiple imputation by chained equations was used to account for missing data. Univariate analyses showed a significant positive correlation between DAS28(ESR) and age or C-reactive protein (CRP) (both p = 0.003), while serum adiponectin level was negatively correlated with DAS28(ESR) (p = 0.015). The negative correlation between adiponectin level and DAS28(ESR) remained true in multivariable analyses adjusted for confounders. In addition, the univariate analyses revealed positive correlations of Sharp score to disease duration (p < 0.001), CRP (p = 0.023) and ESR (p < 0.001). In the multivariable model adjusted for confounders, adiponectin was negatively correlated with Sharp score (p = 0.013). In this single-institution cross-sectional study, serum adiponectin level in treatment-naive RA patients is negatively correlated with DAS28(ESR) and the Sharp score after adjustment for prominent identified confounders. Serum adiponectin may be potentially useful for assessing disease activity and radiographic progression of RA.

Elevated Nesfatin-1 Level in Synovium and Synovial Fluid is Associated with Pro-Inflammatory Cytokines in Patients with Rheumatoid Arthritis

Background

Adipocytokines have been proven to be involved in the progression of autoimmune diseases, including rheumatoid arthritis (RA). Nesfatin-1, a newly discovered adipokine, has recently been reported to possess potent anti-inflammatory, antiapoptotic, and antioxidative properties. However, its role in RA has not yet been reported. Therefore, this study aimed to determine nesfatin-1 levels in the synovium and synovial fluid (SF) of patients with RA and examine their correlation with clinical manifestations and proinflammatory cytokine levels.

Methods

Synovium and SF samples were collected from patients with RA and non-RA patients during joint surgery. Immunohistochemistry was used to measure nesfatin-1 protein expression in the synovium. Enzyme-linked immunosorbent assay was used to measure nesfatin-1, interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) levels in the synovium and SF. Pearson correlation analysis was used to evaluate the correlations between nesfatin-1 levels, RA clinical features, and proinflammatory cytokines. The diagnostic value of synovium nesfatin-1 for RA was assessed using receiver operating characteristic (ROC) curve analysis.

Results

The results showed that nesfatin-1, IL-1β, and TNF-α levels in the synovium were significantly higher in patients with RA than in controls, with age and body mass index as covariates. Moreover, the results of Pearson correlation analysis showed that nesfatin-1 levels were positively correlated with IL-1β and TNF-α levels in the synovium of patients with RA. Furthermore, there was a positive relationship between synovium nesfatin-1 levels and rheumatoid factor in patients with RA. Additionally, the results of the ROC curve analysis revealed an area under the curve of 0.733 with 77.5% sensitivity and 60.0% specificity for synovium nesfatin-1 in discriminating patients with RA from controls.

Conclusion

These findings suggest that increased nesfatin-1 levels in the synovium may be associated with proinflammatory cytokines and RA severity.

Adiponectin Associates with Rheumatoid Arthritis Risk in Overweight and Obesity Independently of Other Adipokines

We recently reported that increased serum adiponectin was associated with rheumatoid arthritis (RA) risk in subjects with obesity. We hereby aim to determine if other adipokines associate with RA risk and if the association between adiponectin and RA is independent of other adipokines. Two nested-case control studies were performed in two different cohorts: 82 participants of the Swedish Obese Subjects (SOS) study who developed RA during follow-up matched with 410 controls, and 88 matched pairs from the Medical Biobank of Northern Sweden. Baseline levels of circulating adipokines were measured using ELISA. In a multivariable analysis in the SOS cohort, higher adiponectin was associated with an increased risk of RA independently of other adipokines (OR for RA risk: 1.06, 95% CI: 1.01–1.12, p = 0.02). No association between leptin, resistin, and visfatin levels and the risk of RA was detected. In the cohort from the Medical Biobank of Northern Sweden, higher adiponectin was associated with an increased risk of RA only in participants with overweight/obesity (OR: 1.17, 95% CI: 1.01−1.36, p = 0.03), independently of other adipokines. Our results show that in individuals with overweight/obesity, higher circulating levels of adiponectin, but not leptin, resistin, or visfatin, were associated with an increased RA risk.