Gene signature profiles in lung tisses of wild type mice or Nrf2 deficient mice infected with my nontuberculous mycobacteria

Background. Nuclear erythroid 2 p45-related factor 2 (Nrf2) regulates the expression of antioxidant and detoxification genes and are thought to be important in protection against intracellular pathogens. The aim of this study was to determine the role of Nrf2 in the host defense against Mycobacterium avium complex (MAC) infection in mice. Methods. Wild-type mice and Nrf2-deficient mice were infected with MAC via intranasal inoculation with 1x107 CFU of Mycobacterium avium subsp. hominissuis. At 2 months after infection, the bronchoalveolar lavage fluid, lung tissues were collected, then, comprehensive transcriptome analysis in the lungs was performed by RNA-seq. Results. Nrf2-deficient mice were highly susceptible to MAC, compared with wild-type mice. There was no significant changes between genotypes in the level of oxidative stress. In addition, the expression of genes related to Th1 immunity and the proportion of Th1 cells were not changed between genotypes. Comprehensive transcriptome analysis showed that the expression of Nramp1 was much lower in the infected lungs of Nrf2-deficient mice than those of Wild-type mice. The expression of Nramp1 was also much lower in the infected alveolar macrophages of Nrf2-deficient mice than those of Wild-type mice. The result of electron microscopy showed that many infected alveolar macrophages from Nrf2-deficient mice were found to contain a large number of intracellular MAC bacteria compare to alveolar macrophages from wild-type mice, due to inhibition of phagolysosome fusion. Conclusions. This study identified that the Nramp1 regulated by Nrf2 is essential in defining the outcome of MAC disease. Nrf2 is a critical determinant for host resistance to MAC infection as a regulator for the expression of Nramp1. 12 strand-specific RNA libraries for high-throughput sequencing were prepared (3 from the lungs of the wild type mice treated with saline, 3 from the lungs of the Nrf2-/- mice treated with saline, 3 from the lungs of the wild type mice infected with M. avium for 2 months, and 3 from the lungs of the Nrf2-/- mice infected with M. avium for 2 months) using the Illumina Stranded mRNA Sample Preparation Kit with 500ng of total RNA according to manufacturer’s instructions.