Human T‐cell lymphotropic virus type 1 (HTLV‐1)‐associated myelopathy/tropical spastic paraparesis (HAM/TSP) disease is a chronic neuroinflammatory disease, which is associated with HTLV‐1 infection. There is no effective and satisfactory treatment of HAM/TSP. It has been shown that curcumin exhibits modulatory effects on apoptosis and cytotoxicity‐related molecules in HAM/TSP patients. In the present study, we examined the effect of curcumin on the gene expression of caspase‐8, caspase‐10, and anti‐apoptotic protein c‐FLIP, in HAM/TSP patients. Furthermore, we compared the expression of these molecules between HAM/TSP and asymptomatic carriers. Real‐time PCR was performed to examine the mRNA expression of caspase‐8, caspase‐10, and c‐FLIP in studied groups. The mRNA expression of caspase‐8 and caspase‐10 was similar before and after curcumin treatment in HAM/TSP patients (P > 0.05). The mRNA expression of c‐FLIPL and c‐FLIPs was higher after curcumin treatment compared with before treatment and significant differences were observed between the two groups (P = 0.004 and P = 0.044, respectively). The mRNA expression levels of caspase‐8, caspase‐10, c‐FLIPL, and c‐FLIPs were not statistically significant between HAM/TSP patients and asymptomatic carriers (P < 0.05).

In conclusion, our results showed that curcumin increased the expression of c‐FLIP in HAM/TSP patients which might suggest that, this molecule is involved in the apoptosis of HTLV‐1‐infected cells. Further studies with large sample size could be useful to clarify the role of this supplement in HAM/TSP patients.