The Brazilian Journal of Infectious Diseases The Brazilian Journal of Infectious Diseases
Braz J Infect Dis 2017;21:386-90 - Vol. 21 Num.4 DOI: 10.1016/j.bjid.2017.03.009
Original article
IL-10 down-regulates the expression of survival associated gene hspX of Mycobacterium tuberculosis in murine macrophage
Babban Jeea,b, Pawan Sharmac, Kiran Katochd, Beenu Joshie, Sudhir Kumar Awasthib,,
a National JALMA Institute for Leprosy and other Mycobacterial Diseases (ICMR), Department of Microbiology and Molecular Biology, Agra, India
b Chhatrapati Shahu Ji Maharaj University, Institute of Life Sciences, Kanpur, India
c International Centre for Genetic Engineering and Biotechnology, Immunology Group, New Delhi, India
d National JALMA Institute for Leprosy and other Mycobacterial Diseases (ICMR), Agra, India
e National JALMA Institute for Leprosy and other Mycobacterial Diseases (ICMR), Department of Immunology, Agra, India
Received 03 October 2016, Accepted 03 March 2017
Abstract

Mycobacterium tuberculosis (MTB) adopts a special survival strategy to overcome the killing mechanism(s) of host immune system. Amongst the many known factors, small heat shock protein 16.3 (sHSP16.3) of MTB encoded by gene hspX has been reported to be critical for the survival of MTB. In the present study, the effect of recombinant murine interferon-gamma (rmIFN-γ) and recombinant murine interleukin-10 (rmIL-10) on the expression of gene hspX of MTB in murine macrophage RAW264.7 has been investigated. By real-time RT-PCR, it was observed that three increasing concentrations (5, 25 and 50ng/ml) of rmIFN-γ significantly up-regulated the expression of hspX whereas similar concentrations of rmIL-10 (5, 25 and 50ng/ml) significantly down-regulated the hspX expression. This effect was not only dependent on the concentration of the stimulus but this was time-dependent as well. A contrasting pattern of hspX expression was observed against combinations of two different concentrations of rmIFN-γ and rmIL-10. The study results suggest that rIL-10 mediated down-regulation of hspX expression, in the presence of low concentration of rIFN-γ, could be used as an important strategy to decrease the dormancy of MTB in its host and thus making MTB susceptible to the standard anti-mycobacterial therapy used for treating tuberculosis. However, as these are only preliminary results in the murine cell line model, this hypothesis needs to be first validated in human cell lines and subsequently in animal models mimicking the latent infection using clinical isolates of MTB before considering the development of modified regimens for humans.

Keywords
Mycobacterium tuberculosis, hspX, rmIFN-γ, rmIL-10, Murine macrophage
Braz J Infect Dis 2017;21:386-90 - Vol. 21 Num.4 DOI: 10.1016/j.bjid.2017.03.009