Análise da expressão de Tax e HBZ e de genes celulares relacionados com a resposta imune inata e adaptativa em portadores assintomáticos e pacientes com HAM/TSP com baixa ou alta carga proviral do HTLV-1 (Human T-lymphotropic vírus 1)

Abstract

About 5% of HTLV-1 carriers may develop an inflammatory disease of the central nervous system known as HAM/TSP (HTLV-1-associated myelopathy/tropical spastic paraparesis). The HTLV-1 proviral load is an important risk marker for diseases associated with the virus, because symptomatic patients have an average proviral load levels significantly higher than asymptomatic carriers. However, there are asymptomatic carriers (AC) with high levels of proviral load, whereas there are patients with HAM/TSP (HAM) with low levels of proviral load. Therefore, other factors are important in the outcome of the diseases associated with HTLV-1. Here, it were evaluated the levels of tax and sHBZ mRNA expression besides 22 cellular genes involved in innate and adaptive immune responses (TLR4, IL-12B, CD40, CD40L, CD80, CD86, CD28, perforin, granzyme, FasL, Fas , IFN-, TNF-, IL-8, IL-10, RANTES, CCR1, MIP-1, MCP-1, CCR2B, LFA-1 and MMP-9) in individuals AC and HAM classified in low (L) or high (H) proviral load level, using real time RT-PCR. The expression of tax and sHBZ mRNA were analyzed in 21 ACL, 16 ACH, 7 HAML and 19 HAMH, and the cellular genes mRNA expression were analyzed in 14 ACL, 9 ACH, 7 HAML and 9 HAMH, beyond 14 seronegative blood donors (SN). There was no significant difference in sHBZ mRNA expression normalized by the proviral load between the AC and HAM groups. In contrast, tax mRNA load normalized by the proviral load was significantly higher in HAM group than in AC group and in the ACH vs. ACL subgroups, but there was no significant difference between HAMH and HAML subgroups. There was significant positive correlation of tax and sHBZ mRNA expression with the proviral load in AC and HAM groups, but it was stronger in the AC group. The expression level of tax and sHBZ mRNA were also positively and significantly correlated in the AC and HAM groups, however it was stronger in HAM group. The data showed that the AC individuals are a more heterogeneous group than HAM in relation to tax and sHBZ mRNAs expression, and should be carefully evaluated when compared with HAM/TSP patients. In conclusion, it is important evaluate the levels of tax and sHBZ mRNA, and not only the HTLV-1 load proviral, to better estimate the risk of development of HAM/TSP. Regarding the 23 cellular genes analyzed, the ACL subgroup showed the largest number of genes with differential mRNA expression of at least two times comparing to the SN group, with decreased levels of TLR4 (-2.51x) and increased levels of IFN- (2.06x), IL-8 (3.6x) and MIP-1 (2.63x). The ACH and HAML subgroups presented only one gene with reduced mRNA expression in relation to SN group (-2.29x of of MIP-1 and -3.37x of MMP9, respectively). The HAMH subgroup not presented mRNA expression variation of at least twice in relation to SN group for none of the genes analyzed. There was a significant difference in Foxp3 mRNA expression between AC and HAM groups, but not between AC and SN or between HAM and SN. Moreover, Foxp3 mRNA expression was correlated with the proviral load, tax and sHBZ mRNA load only in AC group. Together, what differentiated the ACL subgroup from ACH subgroup was the lowest tax mRNA expression, the lower Foxp3 mRNA expression and the increased IFN- mRNA expression. Comparing HAML vs. HAMH subgroups, HAML showed similar level of tax mRNA load, but increased level of IL-10 and reduced level of Foxp3 mRNA expression. Together, the data of gene expression pointed to the importance of the innate immune response in the protection of HTLV-1 and suggests possible genetic component in the susceptibility to HAM/TSP.