Rheumatoid arthritis (RA) is a highly prevalent chronic inflammatory rheumatic disorder leading to functional impairment and sequels. The search for new biomarkers helping in detecting RA subjects of high risk of functional disability is required. Studies showing high follistatin levels in RA have been described; however, none of them have placed focus on the role of follistatin as marker of deteriorated functionality. We aim to identify whether follistatin concentrations could be a potential biomarker of physical disability and disease activity in RA patients. Fifty-seven female RA subjects and 20 age–gender-matched controls were included in a cross-sectional evaluation. An assessment of clinical characteristics, grip strength, gait speed, and muscle mass was conducted. In RA subjects, disability was assessed using HAQ-DI and active disease using the DAS28-ESR. Follistatin levels were measured by ELISA. We compared (a) RA + functional disability and (b) RA + preserved physical function. Serum follistatin levels were increased in RA subjects compared to controls (175 ± 119 vs. 133 ± 47; p = 0.030). Follistatin levels correlated with deteriorated physical function levels (r = 0.491; p < 0.001) and severe activity (r = 0.344; p = 0.009). The RA + functional disability group, as compared to the RA + preserved physical function group, had higher serum follistatin levels (218 ± 159 vs. 141 ± 59; p = 0.030), lower grip strength (7.9 ± 4.6 vs. 14.5 ± 5.1; p < 0.001), reduced gait speed (0.77 ± 0.20 vs. 0.92 ± 0.20; p = 0.010), as well as higher proportions of tender joints ≥4 (48% vs. 16%; p = 0.008), and higher disease activity scores (3.8 ± 1.5 vs. 2.8 ± 1.2; p = 0.008). We concluded that higher follistatin levels are associated with physical functional impairment and the severity of disease activity in women with RA. Future studies are required to evaluate whether these follistatin levels can be related to other outcomes such as labor disability, hospitalization, and falls.

Stress is increasingly recognized as a complex, multidimensional phenomenon shaped by interacting biological, psychological, and social factors, and it has been linked to numerous physical conditions. Several inflammatory and oxidative stress markers have been correlated with perceived stress. However, the combined association of biochemical variables, inflammatory and oxidative stress biomarkers, and DNA methylation with perceived stress has not yet been examined in the Mexican population. Therefore, the objective of this study was to determine such an association in a sample of non-representative Mexican adult individuals. A total of 157 individuals were included, of whom 83 (53%) were women. Women showed higher values of stress than men. In the bivariate correlations, perceived stress correlated negatively with sleep quality, age, total cholesterol, monthly earnings and waist-to-hip ratio and positively with morbidity count, leucocytes and platelets. In the multivariable analyses, additional variables were associated with perceived stress, including a positive correlation with IL-1β in the total sample, a positive correlation with 8-isoprostane in the women’s sample, and a negative correlation with this molecule in the men’s sample. Similarly, perceived stress correlated positively with DNA global methylation in the men’s sample and negatively with this variable in the women’s sample. In conclusion, perceived stress showed correlations with many variables, including sociodemographic and behavioral ones, such as sex, age and sleep quality; biochemical variables, including serum lipids, platelets and leukocytes; and inflammation (IL-1β), oxidative stress (8-isoprostane) and DNA methylation (global DNA methylation) biomarkers, some of them showing opposite correlations in each sex.