Role of resistin as a marker of inflammation in systemic lupus erythematosus

Adiponectin and leptin serum concentrations in patients with rheumatoid arthritis

Adipose tissue is regarded as an active metabolic and endocrine organ producing adipokines. The purpose of the study was to evaluate adiponectin and leptin concentrations in rheumatoid arthritis (RA) patients (pts) in relation to disease duration and activity. The study group consisted of 80 RA pts. Serum adiponectin and leptin concentrations remained within normal ranges. Adiponectin concentration correlated positively both with the age and disease duration. Both adipokines levels correlated negatively with glomerular filtration rate. There were significant positive correlations between adipokines' concentrations and lipid profile components (between adiponectin and HDL-cholesterol, leptin and total cholesterol and LDL-cholesterol). In pts with long-standing RA, there was a negative correlation between adiponectin and numbers of tender, swollen joints and a positive relationship between leptin level and DAS28. The results confirm adipokines' involvement in the process of inflammation and atherosclerosis: protective and antiinflammatory adiponectin effect and proatherogenic and proinflammatory leptin function.

The peroxisome proliferator-activated receptor gamma agonist rosiglitazone ameliorates murine lupus by induction of adiponectin

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease for which current therapy is suboptimal. SLE is characterized by autoantibody production, with renal disease and premature atherosclerosis being common and severe manifestations causing appreciable morbidity and mortality. Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists are widely used in the treatment of diabetes mellitus for their insulin-sensitizing properties, but also have immunomodulatory effects. In this report, we show that the PPARgamma agonist rosiglitazone reduces autoantibody production, renal disease, and atherosclerosis in mouse models of SLE. The beneficial effect of rosiglitazone on SLE manifestations depends on the induction of adiponectin, because rosiglitazone has no effect on autoantibody production or renal disease in lupus mice that lack adiponectin. In addition, lupus mice that lack adiponectin develop more severe disease than adiponectin-sufficient lupus mice, indicating that endogenous adiponectin is involved in regulating disease activity. Furthermore, administration of exogenous adiponectin ameliorates disease. These experiments suggest that PPARgamma agonists may be useful agents for the treatment of SLE. They also demonstrate that induction of adiponectin is a major mechanism underlying the immunomodulatory effects of PPARgamma agonists.

Resistin in serum is associated with higher levels of IL-1Ra in post-menopausal women with rheumatoid arthritis

OBJECTIVES

The aim of this study was to investigate associations between serum levels of resistin, an adipokine and markers of inflammation, bone metabolism, plasma lipids and kidney function in post-menopausal RA patients and to evaluate if HRT during 2 yrs affected resistin levels.

METHODS

Eighty-eight women were randomly allocated to receive HRT, vitamin D(3) and calcium or vitamin D(3) and calcium alone. Serum levels of resistin, IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-6 soluble receptor, TNF-alpha were measured by ELISA, markers of bone metabolism, carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and carboxyterminal propeptide of type I procollagen by RIA, ESR, CRP, Hb, creatinine and lipids by standard laboratory techniques, BMD and total lean mass (TLM) by DXA and joint destruction by Larsen score. Resistin was also measured in 42 healthy control women.

RESULTS

There was no difference in resistin concentration between patients and healthy controls. Resistin was significantly correlated with IL-1Ra, CRP, TNF-alpha, ICTP, glucocorticosteroids and Larsen score and inversely with BMD, hip and with TLM. In multiple regression analysis, IL-1Ra, TLM and use of corticosteroids remained determinants of resistin. Patients treated with HRT displayed significant increase in resistin compared with controls in the first but not the second year.

CONCLUSIONS

Resistin was associated with increased inflammation, particularly by the acute-phase reactant IL-1Ra antagonizing IL-1beta, joint destruction, glucocorticosteroids and with reduced BMD and TLM. These findings suggest resistin being a significant mediator in the inflammatory process in RA. Further studies examining the mechanisms behind the relation between resistin and IL-1Ra are encouraged. HRT does not seem to have important long-term effect on resistin.