Identificação dos subtipos de alelos de HLA-DRB1*04 associados à Tuberculose Pulmonar

Abstract

Tuberculosis (TB) is a serious public health problem, considered as a priority by the government of Brazil since 2003. This disease is endemic in low and middle-income countries, mainly affecting the population living in urban peripheries when associated with poor living conditions, malnutrition and drug abuse. Brazil is one of 22 countries contributing to the global high TB burden; it is on 16th position in number of TB cases. In 2014, Amazonas state had the highest national incidence rate of TB (68.4 per 100.000 inhabitants). Poverty, social exclusion, operational difficulties for diagnosis and treatment of TB are crucial to maintaining the high rate of incidence. In addition, the host immunogenic factors are associated with TB. Human Leukocyte Antigen (HLA) genes are associated with susceptibility or resistance to TB. This study verifies the frequency of HLA-DRB1*04 allele and subtypes in 622 subjects (316 patients with pulmonary TB and 306 controls). HLA-DRB1*04 was more frequent in TB patients (187/316; 59,2%) than control group (101/306; 33,0%). In this study, nine subtypes of HLA-DRB1*04 were identified. The subtype HLA-DRB1*04:11:01 was associated with susceptibility to pulmonary TB (p = 0.0019; OR = 2.23; 95% CI = 1.34 to 3.70), while HLA-DRB1*04:07:01 was associated with protection (p < 0.0001; OR = 0.02; 95% CI = 0.001 to 0.33) and HLA-DRB1*04:92 was associated with transmission to pulmonary TB disease (p = 0.0112; OR = 8.62; 95% CI = 1.63 to 45.5). These results suggest three subtypes of HLA-DRB1*04 as potential immunogenetic markers in TB and can help in better understanding of mechanisms involved in disease, as well as the reasons for high rates of TB incidence in Amazonas state.