Immune profiling of Mycobacterium tuberculosis-specific T cells in recent and remote infection

Abstract

Background Recent Mycobacterium tuberculosis (M.tb) infection is associated with a higher risk of progression to tuberculosis disease, compared to persistent infection after remote exposure. However, current immunodiagnostic tools fail to distinguish between recent and remote infection. We aimed to characterise the immunobiology associated with acquisition of M.tb infection and identify a biomarker that can distinguish recent from remote infection. Methods Healthy South African adolescents were serially tested with QuantiFERON-TB Gold to define recent (QuantiFERON-TB conversion <6 months) and persistent (QuantiFERON-TB+ for >1.5 year) infection. We characterised M.tb-specific CD4 T cell functional (IFN-γ, TNF, IL-2, CD107, CD154), memory (CD45RA, CCR7, CD27, KLRG-1) and activation (HLA-DR) profiles by flow cytometry after CFP-10/ESAT-6 peptide pool or M.tb lysate stimulation. We then assessed the diagnostic performance of immune profiles that were differentially expressed between individuals with recent or persistent QuantiFERON-TB+. Findings CFP-10/ESAT-6-specific CD4 T cell activation but not functional or memory phenotypes distinguished between individuals with recent and persistent QuantiFERON-TB+. In response to M.tb lysate, recent QuantiFERON-TB+ individuals had lower proportions of highly differentiated IFN-γ+TNF+ CD4 T cells expressing a KLRG-1+ effector phenotype and higher proportions of early differentiated IFN-γ-TNF+IL-2+ and activated CD4 T cells compared to persistent QuantiFERON-TB+ individuals. Among all differentially expressed T cell features CFP-10/ESAT-6-specific CD4 T cell activation was the best performing diagnostic biomarker of recent infection. Interpretation Recent M.tb infection is associated with highly activated and moderately differentiated functional M.tb-specific T cell subsets, that can be used as biomarkers to distinguish between recent and remote infection. Funding US National Institutes of Health (NIH), Bill and Melinda Gates Foundation, South African National Research Foundation, South African Medical Research Council, and Aeras.

Mycobacterium tuberculosis Immune Response in Patients With Immune-Mediated Inflammatory Disease

“…The cytokine profile has been evaluated only in patients with a positive total response to the Mtb stimulation using the Boolean gate function of FlowJo software. For responders, we also calculated the functional differentiation score (FDS) as previously described ( 29 , 30 ) by applying the following equation:…”

“…Supplementary Figure 4 | Functional differentiation score (FDS) of Mtb-specific CD4 T cells is similar before and after TB therapy in TBI-IMID, TBI subjects, and active-TB patients. FDS has been calculated as previously described (28,29) The number of CD4 and CD8 responders to TB1 and TB2 stimulation is reported in detail in Table 3. Statistical analysis was performed using the Wilcoxon matchedpairs signed rank test, and the p value was considered significant if ≤0.05.…”

“…Therefore, the different states of Mtb-infection could be identified by the differentiation status and functional ability of T cells (31,32). Recently, it has been demonstrated that highly activated and moderately differentiated functional Mtb-specific T cells are potential immune biomarkers to discriminate recent and remote TBI individuals (29). Active-TB status has been associated to high level of cell-activation markers such as HLA-DR (33)(34)(35)(36)(37) or to the loss of CD27 (38)(39)(40)(41)(42).…”

“…Although a remote Mtb exposure, the TBI-IMID have an intrinsic higher risk to develop the active-TB disease ( 7 , 10 ). In the last decade, several reports proposed that the differentiation status and functional ability of CD4 T cells depended on the degree and length of Mtb exposure ( 29 , 30 ). Therefore, the different states of Mtb-infection could be identified by the differentiation status and functional ability of T cells ( 31 , 32 ).…”

Multidimensional analysis of immune responses identified biomarkers of recent Mycobacterium tuberculosis infection

“…Innate and adaptive effector responses were measured in stimulated PBMCs using flow cytometry ( S1 Text Section 1.2 and [ 29 ]). Five stimulations were used to induce M.tb and non-specific T cell responses in cells of the adaptive arm (adaptive dataset), including M.tb -specific peptide pools spanning E6C10 or EspC, EspF and Rv2348c (collectively termed Esp), and M.tb -lysate, which is a mixture of M.tb -specific antigens, of which some of which are cross-reactive with other mycobacteria; Staphylococcus Enterotoxin B (SEB), as a positive control; or the cells were left unstimulated as a negative control.…”