Efeito da exposição precoce ao poluente 1,2-NQ sobre a resposta imune inata e adquirida de camundongos: papel dos receptores toll.

Santos KT. Effect of early exposure to the air pollutant 1,2-NQ under innate imunity and adaptive response of mice: role of toll-like receptors [PhD thesis (Pharmacology)]. São Paulo: Instituto de Ciências Biomédicas, Universidade de São Paulo; 2013. Daily variations of air pollution, mainly particulate matter (PM2,5) related to traffic, is one of the global public health problems, as they have been consistently associated with increased mortality and respiratory diseases aggravation in susceptible individuals, such as children. The previous scientific contribution of this group on the effects of 1,2-napththoquinone (1,2NQ), a PM2,5 contaminant, showed that exposure of C57BL/6 neonate, but not adult, mice to 1,2-NQ significantly increased susceptibility to allergic lung inflammation at adulthood; however, little is known about the involved mechanisms in vivo. Interestingly, evidences have suggested that diesel exhaust particles (DEP) a ligand of toll 4-like receptors (TLR4). The aim of this study was to investigate the involvement of cell and receptors (e.g.: TLR4) involved in innate/adaptive immunity on the increased susceptibility to allergic inflammation in mice exposed to 1,2-NQ as neonate. We also evaluated impact of 1,2-NQ in both cell population and inflammatory molecules 24 h after exposure to 1,2-NQ. In the thymus of neonate wildtype (WT) mice, but do not the TLR4, exposure to 1,2-NQ markedly increased T CD8 population and the programmed death ligand 1 (PDL-1). In the WT neonate mice splenocytes, but not the TLR4, the exposure to 1,2-NQ significantly increased CD11c cell population and co-stimulatory molecules (CD80 and CD86). The in vivo exacerbation of allergic inflammation in the airways, characterized by lung eosinophilia (bronchoalveolar lavage; BAL), peripheral blood and bone marrow, concomitantly with elevated levels of plasmatic IgE and increased lung Th2 cytokines (IL-4 and IL5), without changes in the airway responsiveness (penh), was observed in allergic WT mice exposed to 1,2-NQ when compared to group exposed to antigen ovalbumin only (OVA). In both TLR4 and MyD88 mice, the increased lung inflammatory response was abolished as compared to its matched allergic group. In the lung of WT mice, the early contact with 1,2-NQ increased mRNA expression of TLRs (2, 4 and 7) and the adapter molecule TRIF, and the transcription factors GATA3 and T-bet. In TLR4 mice exposed to 1,2-NQ, TRIF expression did not change as compared to WT mice exposed to 1,2-NQ; however, the MyD88 mRNA expression increased, while GATA3 and T-bet mRNA expression were abolished. In the lung of neonate WT mice, the early exposure to 1,2-NQ increased HSP70 protein expression and p50 subunit of NF-κB nuclear translocation concomitantly with decreased AP-1 activation. This study showed, for the first time, that early contact with 1,2-NQ induces innate immune responses, partly via TLR4 (and possibly TLR2 and TLR7) pathway dependent on MyD88. This may change the adaptive response at adulthood and contribute to pulmonary illnesses in children in heavy polluted areas.