ASSOCIATION BETWEEN FAS/FASL EXPRESSION AND RHEUMATOLOGICAL MANIFESTATIONS IN PATIENTS INFECTED WITH HTLV-1

Introduction: Fas and FasL are known modulators of cellular apoptosis in immunoregulation of the innate immune response, as well as in the elimination of defective cells, and may be associated with antiviral activity of HTLV-1 – infected cells. Understanding the immunological mechanisms involved in the progression of HTLV-1 – associated diseases may contribute to predicting the clinical prognosis of infected individuals. Objective: To evaluate mRNA expression of the apoptotic modulators FAS and FASL in patients infected with HTLV-1. Methods: A total of 54 HTLV-1 – infected individuals were evaluated, including 31 symptomatic patients with virus-associated diseases (HAM, neurological diseases, and rheumatological diseases) and 23 asymptomatic individuals. For FAS and FASL gene expression, RNA was extracted and converted to complementary DNA from all samples, followed by quantification of gene expression by real-time PCR. Plasma IFN-γ (interferon-gamma) levels were measured by ELISA. Statistical analyses used Kruskal–Wallis and Spearman tests. Results: FASL expression levels were higher among asymptomatic patients compared with patients with different HTLV-1 – associated diseases, although without statistical significance (p=0.7030). There was no significant association between FAS expression levels in asymptomatic individuals and patients with HAM (p≥0.9999), neurological diseases (p=0.8409), or rheumatological diseases (p=0.5971). However, FAS expression levels were significantly higher in patients with rheumatological diseases compared with those with neurological diseases (p=0.0432). Comparison of plasma IFN-γ levels between symptomatic and asymptomatic patients showed no statistically significant differences (p=0.2678). In addition, no statistically significant correlation was observed between FAS and FASL gene expression and IFN-γ levels (p≥0.005). Conclusion: Although no significant correlation was observed between FAS, FASL expression and IFN-γ production, the statistically significant difference in FAS expression between patients with rheumatological and neurological diseases suggests a possible role of this gene in immunological modulation associated with different clinical manifestation profiles in HTLV-1–infected patients.