Differential Early Secreted Antigen Target (ESAT) 6 kDa–induced IFN-γ and SOCS1 expression distinguishes latent and active tuberculosis

  • Kiran Iqbal Masood The Aga Khan University, P.O. Box 3500, Stadium Road, Karachi 74800, Pakistan
  • Rabia Hussain The Aga Khan University, P.O. Box 3500, Stadium Road, Karachi 74800, Pakistan
  • Nisar Rao OJHA Institute of Chest Diseases, DOW University of Health Sciences, Karachi, Pakistan
  • Martin E Rottenberg Karolinska Institutet, Stockholm, Sweden
  • Naseem Salahuddin Indus Hospital, Karachi, Pakistan
  • Muhammad Irfan The Aga Khan University, P.O. Box 3500, Stadium Road, Karachi 74800, Pakistan
  • Zahra Hasan The Aga Khan University, P.O. Box 3500, Stadium Road, Karachi 74800, Pakistan
Keywords: ESAT6, SOCS1, tuberculosis, IFN-γ, pulmonary TB, extra-pulmonary TB

Abstract

Introduction: Expression of Suppressor of cytokine signaling (SOCS)-1 molecules is increased in patients with tuberculosis (TB). Early Secreted Antigen Target (ESAT)-6 kDa – induced IFN-γ responses indicate Mycobacterium tuberculosis infection. The effect of ESAT6- stimulation on SOCS1 in the host is not known.

Methodology: Healthy asymptomatic controls had a negative (n = 16) or a positive ( n = 13) tuberculin skin test (TST). ESAT6-induced IFN- γ responses classified these controls as positive (EC ESAT6 IFN-γ (+), n = 5) or negative (EC ESAT6 IFN-γ (-), n = 24) responders. Patients had pulmonary (n = 21) or extra-pulmonary (n = 30) tuberculosis. Peripheral blood cells were stimulated with ESAT6 and mRNA expression of IFN- γ and SOCS1 was determined.

Results: ESAT6-induced IFN-γ expression was raised in EC ESAT6 IFN-γ (+) as compared with EC ESAT6 IFN-γ (-), p = 0.019. ESAT6-induced SOCS1 mRNA expression was increased in both pulmonary TB and extra-pulmonary TB patients as compared with both EC groups. ESAT6-induced IFN-γ/SOCS1 mRNA expression ratio was decreased in TB patients as compared with both EC groups.

Conclusion: M. tuberculosis infection induces increased ESAT6-induced IFN- γ responses in both latent and active TB. Our data shows down-regulation of IFN- γ / SOCS1 expression to be induced only in active TB cases, distinguishing them from healthy individuals likely to have latent TB. A decreasing IFN- γ /SOCS1 ratio may leads to reduced Th1 immunity which contributes to inability of the host to control clinical disease.

Published
2014-01-15
How to Cite
1.
Masood KI, Hussain R, Rao N, Rottenberg ME, Salahuddin N, Irfan M, Hasan Z (2014) Differential Early Secreted Antigen Target (ESAT) 6 kDa–induced IFN-γ and SOCS1 expression distinguishes latent and active tuberculosis. J Infect Dev Ctries 8:059-066. doi: 10.3855/jidc.3412
Section
Original Articles