Background Adipose tissue has the ability to release a wide range of mediators involved in the inflammatory response
Objectives To investigate spontaneous adipocytokine secretion by subcutaneous abdominal adipose tissue (SAAT) explants obtained from patients with rheumatoid arthritis (RA).
Methods SAAT explants were obtained by 18G needle biopsy from 84 RA patients (62F/22M, the mean age 58,9±12,5 years) dispersed and cultured in vitro (100mg tissue/ml). Selected adipocytokines: leptin, adiponectin, TNF, IL-6, IL-8, MIF concentrations were measured in culture supernatants using ELISA and in sera of patients. Body mass index (BMI), body composition measurements: percentage of body fat, fat mass index, (FMI) fat free mass index (FFMI), visceral fat index (VFI), systematic coronary risk evaluation index (SCORE), disease activity scores (DAS 28), x-ray Larsen scores, routine blood tests and basic demographic and clinical information were obtained. Associations of BMI, body composition parameters with DAS28, CRP levels, ESR, X-ray scores and concentrations of adipocytokines were evaluated using multiple linear regression. The spontaneous adipocytokine secretion from SAAT was compared with the serum levels of measured variables.
Results Disease activity of RA patients was high (DAS 28=5,4±1,1 SD, CRP levels 26,2±22). Mean disease duration was 11,6±10,5 years, patients BMI 26,3±5,3, body fat 29,2±9,2%, fat mass 21,2±10,7kg, visceral index 8,3±3,2. The SAAT secretion of IL-6 (3477±10205pg/ml), IL-8 (9896±20548pg/ml), MIF (2739±1749pg/ml) were significantly higher comparing to the serum levels of IL-6 (517±1235pg/ml), IL-8 (75±177pg/ml), MIF (581±629pg/ml). The SAAT leptin (1,325±0,97pg/ml) was significantly lower then the serum leptin levels (21,34±20,46pg/ml). BMI values of patients correlated positively with the serum leptin level (r=0,56, p<0,05) and negatively with the SAAT adiponectin concentration (r=-0,43 p<0,05). The SCORE values correlated positively with the SAAT MIF levels (r=0,3 p<0.05). We performed regression analysis for DAS28, cytokines concentrations and body composition parameters. In the first model DAS28 was positively and significantly associated with the SAAT IL-8 concentration and BMI, and inversely and significantly correlated with VFI. In the second model DAS28 was positively and significantly associated with the SAAT TNF secretion and BMI, and inversely and significantly associated with VFI.
Conclusions SAAT is a rich source of adipocytokines. Spontaneous secretion of some adipokines by adipose tissue correlates positively with disease activity (TNF, IL8), and MIF secretion correlates with SCORE, suggesting SAAT contribution to clinical manifestation of RA. Interestingly, in our study, serum adipocytokine levels fail to show such association.
Disclosure of Interest None declared