Avaliação da composição corporal, dos níveis de citocinas pró-inflamatórias e de proteínas do sistema osteoprotegerina-rankl em pacientes com psoríase e controles

Abstract

Introduction: Psoriasis is a chronic inflammatory skin disease that occurs in about 1.5- 2% of the world population. Several diseases have been associated with psoriasis as cardiovascular diseases, diabetes mellitus and dyslipidemia. This association is related to the chronic inflammatory process. Current advances in the pathogenesis ofosteoporosis have observed the participation of cytokines such as IFN-, IL-6 and TNF- that are also involved in the pathogenesis of psoriasis. It has been questioned if psoriasis could compromise bone mineral density (BMD). Objectives: Assess the frequency of adiposity through the body mass index (BMI), waist circumference (WC) and absorptiometry dual energy x-ray (DXA) in psoriasis patients and controls and determine the correlation between these different measures of adiposity. Assess and compare the body composition of patients with psoriasis andcontrols. To determine the serum levels of pro-inflammatory cytokines (TNF-, INF- , IL-2, IL-4, IL-12, IL-23, IL-10, IL-17A and IL-6) and bone metabolism markers such as CTx (carboxyterminal telopeptide of collagen), the binding of the activator of nuclear factor kappa B (RANKL), osteoprotegerin (OPG) in patients with psoriasis and controls. Correlate the values of these pro-inflammatory cytokines and bone markerswith BMD and bone mineral content (BMC) in the patients studied.Methods: From May to November 2012, 42 patients with psoriasis and 41 controls matched for sex and age were included in the study. All of them underwent clinical examination with assessment of BMI and WC, the DXA, and dosage of serum bone markers and inflammatory cytokines. In the comparison between cases and controls, Pearson's, Fisher's exact and Mann-Whitney tests were used. The agreement betweenthe different methods of assessing obesity was evaluated using the weighted kappa coefficient and the difference between these methods was evaluated using the McNemar test. After univariate analysis proceeded to the multivariate analysis to identify the factors associated with BMD and BMC in patients. In all analyzes we considered asignificance level of 5%. SPSS 15.0 software was used. Results: Patients with psoriasis had a median age of 47 years, 59.5% male. The mediantime of psoriasis reported was ten years. Thirty-seven patients (88%) were classified as mild psoriasis. The controls had a median age of 38 years and 53.7% were male. There was no difference in the prevalence of obesity among cases and controls by different methods. Both BMI and the WC had poor agreement with the body fat measures assessed by DXA. The cases showed a trend toward lower total BMC (p = 0.059). Stratified analysis by gender showed that male patients had lower BMC (p=0.007) and lower BMD (p = 0.027) compared to controls of the same gender. No difference between groups was found in relation to other indices of body composition. Patients with psoriasis had higher levels of OPG, IL-12, IL-10, IL-6, IL-4 and IL-2 (p <0.05) compared to controls. There was no difference between groups for the dosages of IL-23, RANK-L, CTX, IL-17A, IFN- and TNF-. Patients with psoriasis under systemictreatment had lower levels of TNF- than patients only under topical treatment.Psoriatic patients showed an inverse correlation of OPG, IL-6, IL-17 and IL-23 with the variables related to DMO and CMO. Conclusion: DXA was more effective in identifying obesity compared with the CA andBMI, both in psoriasis patients and controls. Male patients with psoriasis had lower BMC than controls. Psoriasis patients have higher levels of inflammatory cytokines that are important in the pathogenesis of psoriasis as well as OPG, probably a compensatory response to increased osteoclastogenesis that may be present in these patients. Theinverse correlation between BMD and BMC with important cytokines in thepathogenesis of psoriasis signals the possibility of a negative influence of these cytokines on bone metabolism.