UNIVERSIDADE FEDERAL DE PERNAMBUCO CENTRO DE CIÊNCIAS BIOLÓGICAS PROGRAMA DE PÓS-GRADUAÇÃO EM INOVAÇÃO TERAPÊUTICA

SOUZA, M. A. Quantitation of mediators from Th1, Th2, Th17 and Treg profiles in the immune response against active American Tegumentary Leishmaniasis and after clinical cure. Thesis (Doctorate). Federal University of Pernambuco, Recife, Pernambuco, Brazil, 2014. The classical model of susceptibility and resistance to leishmaniasis suggests that Th1 or Th2 expansion directs the outcome of the infection. Recently, the Th17 profile was related to the disease and seems to be antagonistic to the regulatory T cells (Treg). Thus, this study had as objective to quantify, through capture ELISA or qPCR, some mediators of Th1, Th2, Th17 and Treg profiles (IFN-γ, TNF-α, IL-10, IL-4, TGF-β, IL-6, IL-17, IL-22, RORC, Foxp3 and iNOS) in patients with active (AD) american tegumentary leishmaniasis (ATL) and after clinical cure, treated (AT) or not (spontaneous healing; SH). The patients were capable of presenting specific immune response to the soluble (AgSol) and insoluble (AgIns) of L. (V.) braziliensis in relation to the control group. The first article demonstrated that, in response to AgSol, there was the predominance of IFN-γ (P = 0,0061) and TNF-α (P = 0,008) during the active disease, indicating the presence of an inflammatory response; IL-17 is also evidenced in this clinical state (P = 0,04). An increase in NO secretion was observed in SH (P = 0,023), whereas IL-17 was observed in low levels in these patients, suggesting that it may be regulated by NO. The presence of IL-10 and IL-22 was observed in all groups (P > 0,05). In the second article, AgIns stimulated significant IFNγ production in all groups (P < 0,05). AD (P = 0,007) and AT (P = 0,003) produced TNF-α. On the other hand, the SH group presented low levels of the cytokine. Interestingly, NO secretion was significant in these individuals (P = 0,04), whereas IL-17 was observed in low levels. Significant IL-17 production was observed in AT group (P = 0,04). Although IL-22 was detected in AD (P = 0,02), its role is questionable. The presence of IL-10 in all groups of patients suggests that the cytokine exerts different roles different roles in the disease (P > 0,05). In the third article, PBMC from patients with active lesions expressed mRNA for IFN-γ (AgSol: P = 0,017; AgIns: P = 0,0004) and TNF-α (AgSol: 0,0306; AgIns: P = 0,027), reinforcing the possible presence of an inflammatory response. The absence of mRNA for iNOS in these patients may be due the presence of secreted NO, representing a feedback mechanism. This event may help to impair the exacerbation of the immune response. Furthermore, the significant presence of mRNA for IL-10 (AgSol: P = 0,0119; AgIns: P = 0,0114) suggests that immunomodulatory mechanisms favor an effective immune response against Leishmania. Foxp3 expression to AgIns (P = 0,0208) indicates that regulatory T cells are present in the response of patients with active lesions. Although IL-17 and IL-22 seem to be important in the effective immune response in ATL, the mRNA levels for these cytokines were not significant (P > 0,05). However, IL-6 levels expressed by the patients (AgSol: P = 0,0189) with active disease seem to have been insufficient to induce a Th17 profile along with TGF-β (P > 0,05), given the non-significant expression of RORC (P > 0,05). TGF-β expression may have contributed to the regulation of the immune response by Treg cells, what reinforces the supposed antagonism between this and the Th17 profile. Thus, the secretion/expression of these mediators reinforces the complexity of the cellular immune response in the fight against Leishmania, and provides informations for the development of vaccines and immunotherapeutic schemes.