Immune Responses of HIV-1 Tat Transgenic Mice to Mycobacterium Tuberculosis W-Beijing SA161
Jennifer R Honda*, 1, Shaobin Shang 2, §, Crystal A Shanley 2, Megan L Caraway 2, Marcela Henao-Tamayo 2, Edward D Chan 3, Randall J Basaraba 2, Ian M Orme 2, Diane J Ordway§, 2, Sonia C Flores 1
Identifiers and Pagination:Year: 2011
First Page: 86
Last Page: 95
Publisher Id: TOAIDJ-5-86
Article History:Received Date: 18/2/2011
Revision Received Date: 22/4/2011
Acceptance Date: 11/5/2011
Electronic publication date: 19/10/2011
Collection year: 2011
open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.
Mycobacterium tuberculosis remains among the leading causes of death from an infectious agent in the world and exacerbates disease caused by the human immunodeficiency virus (HIV). HIV infected individuals are prone to lung infections by a variety of microbial pathogens, including M. tuberculosis. While the destruction of the adaptive immune response by HIV is well understood, the actual pathogenesis of tuberculosis in co-infected individuals remains unclear. Tat is an HIV protein essential for efficient viral gene transcription, is secreted from infected cells, and is known to influence a variety of host inflammatory responses. We hypothesize Tat contributes to pathophysiological changes in the lung microenvironment, resulting in impaired host immune responses to infection by M. tuberculosis.
Herein, we show transgenic mice that express Tat by lung alveolar cells are more susceptible than non-transgenic control littermates to a low-dose aerosol infection of M. tuberculosis W-Beijing SA161. Survival assays demonstrate accelerated mortality rates of the Tat transgenic mice compared to non-transgenics. Tat transgenic mice also showed poorly organized lung granulomata-like lesions. Analysis of the host immune response using quantitative RT-PCR, flow cytometry for surface markers, and intracellular cytokine staining showed increased expression of pro-inflammatory cytokines in the lungs, increased numbers of cells expressing ICAM1, increased numbers of CD4+CD25+Foxp3+ T regulatory cells, and IL-4 producing CD4+ T cells in the Tat transgenics compared to infected non-tg mice.
Our data show quantitative differences in the inflammatory response to the SA161 clinical isolate of M. tuberculosis W-Beijing between Tat transgenic and non-transgenic mice, suggesting Tat contributes to the pathogenesis of tuberculosis.