Dynamics of Adrenal Steroids Are Related to Variations in Th1 and Treg Populations during Mycobacterium tuberculosis Infection in HIV Positive Persons

Tuberculosis (TB) remains the most frequent cause of illness and death from an infectious agent, and its interaction with HIV has devastating effects. We determined plasma levels of dehydroepiandrosterone (DHEA), its circulating form DHEA-suphate (DHEA-s) and cortisol in different stages of M. tuberculosis infection, and explored their role on the Th1 and Treg populations during different scenarios of HIV-TB coinfection, including the immune reconstitution inflammatory syndrome (IRIS), a condition related to antiretroviral treatment. DHEA levels were diminished in HIV-TB and HIV-TB IRIS patients compared to healthy donors (HD), HIV+ individuals and HIV+ individuals with latent TB (HIV-LTB), whereas dehydroepiandrosterone sulfate (DHEA-s) levels were markedly diminished in HIV-TB IRIS individuals. HIV-TB and IRIS patients presented a cortisol/DHEA ratio significantly higher than HIV+, HIV-LTB and HD individuals. A positive correlation was observed between DHEA-s and CD4 count among HIV-TB individuals. Conversely, cortisol plasma level inversely correlated with CD4 count within HIV-TB individuals. M. tuberculosis-specific Th1 lymphocyte count was increased after culturing PBMC from HIV-TB individuals in presence of DHEA. We observed an inverse correlation between DHEA-s plasma level and Treg frequency in co-infected individuals, and CD4+FoxP3+ Treg frequency was increased in HIV-TB and IRIS patients compared to other groups. Strikingly, we observed a prominent CD4+CD25-FoxP3+ population across HIV-TB and HIV-TB IRIS patients, which frequency correlated with DHEA plasma level. Finally, DHEA treatment negatively regulated FoxP3 expression without altering Treg frequency in co-infected patients. These data suggest an enhancing role for DHEA in the immune response against M. tuberculosis during HIV-TB coinfection and IRIS

Immunoendocrine Interactions during HIV-TB Coinfection: Implications for the Design of New Adjuvant Therapies

Worldwide, around 14 million individuals are coinfected with both tuberculosis (TB) and human immunodeficiency virus (HIV). In coinfected individuals, both pathogens weaken immunological system synergistically through mechanisms that are not fully understood. During both HIV and TB infections, there is a chronic state of inflammation associated to dramatic changes in immune cytokine and endocrine hormone levels. Despite this, the relevance of immunoendocrine interaction on both the orchestration of an effective immune response against both pathogens and the control of the chronic inflammation induced during HIV, TB, or both infections is still controversial. The present study reviews immunoendocrine interactions occurring during HIV and TB infections. We also expose our own findings on immunoendocrine cross talk in HIV-TB coinfection. Finally, we evaluate the use of adrenal hormones and their derivatives in immune-therapy and discuss the use of some of these compounds like the adjuvant for the prevention and treatment of TB in HIV patients

DHEA modulates the expression of the FoxP3 transcription factor in coinfected individuals. A and B.

<p>Percentages of Treg cells (defined as CD4+FoxP3+CD25+) in PBMC from <b>A.</b> HIV-TB and <b>B.</b> HD individuals stimulated with <i>M. tuberculosis</i> antigen in the presence or absence of DHEA at the indicated concentrations for 3 days. Bars indicate the mean ± SEM for each experimental condition. <b>C and D.</b> Relative FoxP3 Median florescence intensity (MFI) in Treg lymphocytes from <b>C.</b> HIV-TB patients and <b>D.</b> HD volunteers after culturing PBMC as detailed in A. Bars indicate the mean ± SEM for each treatment. Data are representative of four different experiments. *: <i>p</i> < 0.05; **: <i>p</i> < 0.01. <b>E.</b> Representative flow cytometry graphs depicting the results obtained from culturing PBMC from HIV-TB and HD individuals as indicated above.</p

Epidemiological characteristics of the subjects enrolled.

<p>BCG, Bacillus Calmette-Guerin. IQR, Interquartile range.</p

Modulation of <i>M. tuberculosis</i>-induced IFN-γ production by adrenal hormones.

<p><b>A.</b> Absolute numbers of IFN-γ producer cells from PBMC of HIV+, HIV-TB, IRIS, HIV-LTB and HD patients, which have been stimulated with <i>M. tuberculosis</i> antigen for 16 hours. Horizontal lines indicate the mean and comparisons between groups and statistically significant differences are shown. SFU, Spots forming units. <b>B.</b> Percentage of IFN-γ producer cells relative to <i>M. tuberculosis</i> in PBMC of HIV-TB patients (n = 12). PBMC (10⁵ cells/well) were stimulated in the presence of <i>M. tuberculosis</i> with or without addition of DHEA and/or cortisol at the indicated concentrations. Each bar illustrates the mean ± SEM of the percentage for IFN-γ producer cells relative to <i>M. tuberculosis</i> for the each group, calculated as follows: % of IFN-γ relative to <i>Mtb</i> = ([(<i>Mtb</i> hormone-Media)-(<i>Mtb</i>-Media)]/(<i>Mtb</i>-Media))×100. Asterisks indicate comparisons between each condition against <i>Mtb</i> specific response. *: <i>p</i> < 0.05; **: <i>p</i> < 0.01.</p

Cortisol, dehidroepindrosterone-sulfate (DHEA-s), DHEA levels and Cortisol/DHEA ratio in HIV, HIV-TB, IRIS, HIV-LTB and HD.

<p><b>A.</b> DHEA, <b>B.</b> DHEA-s, <b>C.</b> Cortisol and <b>D.</b> Cortisol/DHEA (ratio) levels in plasma of HIV+, HIV-TB, IRIS, HIV-LTB, and HD individuals. Bars indicate the mean ± SEM for each group. Horizontal lines indicate comparisons between groups and statistically significant differences. DHEA was measured by radioimmunoassay, DHEA-s by immunochemoluminiscence tests and Cortisol by electrochemiluminescence. HIV+ individuals n = 10, HIV-TB n = 21, IRIS n = 6, HIV-LTB n = 5, and HD n = 16. *: <i>p</i> < 0.05; **: <i>p</i> < 0.01; ***: <i>p</i> < 0.001.</p

Expanded “non-conventional” Treg in HIV-TB and IRIS patients.

<p>Analysis of CD4+FoxP3+CD25+ and CD4+FoxP3+CD25- populations within Treg in <b>A;</b> HIV-TB (n = 11), <b>B;</b> IRIS (n = 5), <b>C;</b> HIV-LTB (n = 4), <b>D;</b> HD (n = 10) and <b>E;</b> HIV (n = 7) individuals. Horizontal lines inside the boxes indicate the means ± SEM of each group. Asterisks denote comparisons between each sub-population. *: p < 0.05; **: p < 0.01; ***: p< 0.001. <b>F.</b> Spearman correlation analysis between plasma DHEA and the percentage of CD4+FoxP3+CD25- lymphocytes from all grouped patients (HIV+, HIV-TB, IRIS, HIV-LTB and HD). Results of statistical analysis are shown in the graphic.</p