Viduals (i-hHC) had significantly higher lymphocyte proportions than both the IC

Viduals (i-hHC) had significantly higher lymphocyte proportions than both the IC and the NI-CC (figure 8C). We tried to identify the characteristics distinguishing between those individuals who were able to control their infection and those who became 22948146 ill (protected and non protected) by analysing the data on the 3PO factors which were different between the groups, namely FLIPs and TNFR2 expression, and lymphocyte and monocyte counts. Combination of these four factors (Figure 9) gives a signature that could distinguish the IC group, infected hHC(i-hHC with TST.14 mm) and non infected CC (NI-CC with TST,5 mm). According to these parameters, high levels of FLIPs expression were associated with Mtb infection, but those who are able to maintain a higher ratio of lymphocytes and low monocyte levels are able to control this infection.DiscussionThe progression of Mtb infection to active TB disease may take several years to decades, and infections may remain asymptomatic. Individuals with LTBI constitute a major reservoir of potential new active TB cases that could maintain the pandemic transmission of TB. This study was driven by the need for the characterization of surrogate markers of a protective immune response to Mtb infection or of progression to active TB disease. Current diagnostic tests for TB cannot distinguish between active disease and latent Mtb infection. Some diagnostic tests are based on the cell-mediated immunity of the host against MtbApoptosis-Related Gene Expression in TuberculosisFigure 5. Peripheral blood gene expression as a function of PPD-IFN-c-ELISPOT response in the clinical groups. (A) TNFR1, (B) TNFR2, (C) FLIPs, (D) FLICE. ELISPOT positivity was defined as described in the Materials and Methods. The data shown are the median and ranges of mRNA levels normalized and expressed as the number of copies per 105 copies of mRNA for the housekeeping gene, HuPO. Sudan I site Significant differences in gene expression between clinical groups are indicated. doi:10.1371/journal.pone.0061154.gwhere a Th1 cytokine profile response has an important role, but this response is apparently unable to distinguish active disease from latent Mtb infection. TNF-a is an important part of this response, as indicated by the reactivation of disease by anti-TNF-a therapy [27]. We therefore looked at TNF-a-stimulated apoptotic genes since apoptosis of infected macrophages also plays an important role in controlling Mtb infection and regulating cellmediated immunity to the pathogen [13,15,28,29]. The expression of four genes associated with TNF-a-dependent apoptosis and downstream apoptotic effectors was quantified in the peripheral blood of patients with active TB, their household contacts and matched community controls. As summarized in figure 9, the different clinical groups could be characterized on the basis of a combination of expression levels for FLIPs and TNFR2 and the distributions of lymphocytes and monocytes in peripheral blood. Higher levels of expression of FLIPs in the peripheral blood seemed to be associated with Mtbinfection, as FLIPs mRNA in the i-hHC and IC were significantly higher than those in the other groups. This higher level of FLIPs mRNA was also found in TST-positive and PPD or ESAT-6 ELISPOT-positive individuals. FLIPs gene expression was also significantly upregulated in the HC after three months of followup, as shown by comparisons with mRNA levels on inclusion in the study, while no such change was observed over the same period f.Viduals (i-hHC) had significantly higher lymphocyte proportions than both the IC and the NI-CC (figure 8C). We tried to identify the characteristics distinguishing between those individuals who were able to control their infection and those who became 22948146 ill (protected and non protected) by analysing the data on the factors which were different between the groups, namely FLIPs and TNFR2 expression, and lymphocyte and monocyte counts. Combination of these four factors (Figure 9) gives a signature that could distinguish the IC group, infected hHC(i-hHC with TST.14 mm) and non infected CC (NI-CC with TST,5 mm). According to these parameters, high levels of FLIPs expression were associated with Mtb infection, but those who are able to maintain a higher ratio of lymphocytes and low monocyte levels are able to control this infection.DiscussionThe progression of Mtb infection to active TB disease may take several years to decades, and infections may remain asymptomatic. Individuals with LTBI constitute a major reservoir of potential new active TB cases that could maintain the pandemic transmission of TB. This study was driven by the need for the characterization of surrogate markers of a protective immune response to Mtb infection or of progression to active TB disease. Current diagnostic tests for TB cannot distinguish between active disease and latent Mtb infection. Some diagnostic tests are based on the cell-mediated immunity of the host against MtbApoptosis-Related Gene Expression in TuberculosisFigure 5. Peripheral blood gene expression as a function of PPD-IFN-c-ELISPOT response in the clinical groups. (A) TNFR1, (B) TNFR2, (C) FLIPs, (D) FLICE. ELISPOT positivity was defined as described in the Materials and Methods. The data shown are the median and ranges of mRNA levels normalized and expressed as the number of copies per 105 copies of mRNA for the housekeeping gene, HuPO. Significant differences in gene expression between clinical groups are indicated. doi:10.1371/journal.pone.0061154.gwhere a Th1 cytokine profile response has an important role, but this response is apparently unable to distinguish active disease from latent Mtb infection. TNF-a is an important part of this response, as indicated by the reactivation of disease by anti-TNF-a therapy [27]. We therefore looked at TNF-a-stimulated apoptotic genes since apoptosis of infected macrophages also plays an important role in controlling Mtb infection and regulating cellmediated immunity to the pathogen [13,15,28,29]. The expression of four genes associated with TNF-a-dependent apoptosis and downstream apoptotic effectors was quantified in the peripheral blood of patients with active TB, their household contacts and matched community controls. As summarized in figure 9, the different clinical groups could be characterized on the basis of a combination of expression levels for FLIPs and TNFR2 and the distributions of lymphocytes and monocytes in peripheral blood. Higher levels of expression of FLIPs in the peripheral blood seemed to be associated with Mtbinfection, as FLIPs mRNA in the i-hHC and IC were significantly higher than those in the other groups. This higher level of FLIPs mRNA was also found in TST-positive and PPD or ESAT-6 ELISPOT-positive individuals. FLIPs gene expression was also significantly upregulated in the HC after three months of followup, as shown by comparisons with mRNA levels on inclusion in the study, while no such change was observed over the same period f.