Mono- and poly-functional T cells in nontuberculous mycobacteria lung disease patients: Implications in analyzing risk of disease progression

AT A GLANCE

The diagnosis and progression of nontuberculous mycobacteria lung disease (NTN-LD) are important for clinical judgement but cannot easily be predicted. The immunological response of mono- and poly-functional T cells, a representative of host reactivity to NTM, could be a surrogate biomarker for disease and progression prediction.

BACKGROUND

Mycobacterium avium complex (MAC) and M. abscessus (MAB) induced lung disease (LD) have become a clinical concern. Predicting clinical disease relevance and progression is important, but suitable biomarkers are lacking. The host immune response of mono- and poly-functional T cells might aid in clinical judgement.

METHODS

We enrolled 140 participants, including 42 MAC-LD, 25 MAB-LD, 31 MAC airway colonization (MAC-Co), 15 MAB-Co patients, and 27 healthy controls. Their blood mono- and poly-functional T cells were measured and analyzed after in-vitro stimulation.

RESULTS

Patients with MAC-LD generally had lower total IFN-γ+, total TNF-α+ and triple-positive T cells but higher mono-IL-2+ expression than the controls and MAC-Co group. The MAB-LD group had lower total IL-2 and triple positive cells than the controls and colonization group. Multivariate analysis revealed that body mass index (BMI), mono-IL2+ CD4+ and triple positive-CD8+ cells (PMA stimulation) significantly predicted MAC-LD from the controls. By contrast, male gender and triple positive-CD4+ cells predicted MAC-LD from colonization. On the other hand, the triple positive-CD4+ cells (PMA stimulation) alone or together with the mock/MAB ratio of IL-2+/TNF-α+ CD4 cells could predict MAB-LD in the MAB-Co group or the controls. Among MAC/MAB-LD patients without anti-mycobacterial treatment, MAC-specific mono-IFN-γ+ CD4+ cells and PMA-induced triple positive-CD4+ cells were correlated with progression, with an area under the ROC curve of 0.875.

CONCLUSIONS

The patients with MAC/MAB-LD had attenuated poly-functional T cells. The triple-positive CD4+ cells could be useful in diagnosing disease from colonization. MAC-specific mono-IFN-γ+ CD4+ cells and triple positive-CD4+ might predict radiographic progression, which could be useful in making treatment decisions.

Mycobacterium indicus pranii as a booster vaccine enhances BCG induced immunity and confers higher protection in animal models of tuberculosis

BCG, the only approved vaccine protects against severe form of childhood tuberculosis but its protective efficacy wanes in adolescence. BCG has reduced the incidence of infant TB considerably in endemic areas; therefore prime-boost strategy is the most realistic measure for control of tuberculosis in near future. Mycobacterium indicus pranii (MIP) shares significant antigenic repertoire with Mtb and BCG and has been shown to impart significant protection in animal models of tuberculosis. In this study, MIP was given as a booster to BCG vaccine which enhanced the BCG mediated immune response, resulting in higher protection. MIP booster via aerosol route was found to be more effective in protection than subcutaneous route of booster immunization. Pro-inflammatory cytokines like IFN-γ, IL-12 and IL-17 were induced at higher level in infected lungs of 'BCG-MIP' group both at mRNA expression level and in secretory form when compared with 'only BCG' group. BCG-MIP groups had increased frequency of multifunctional T cells with high MFI for IFN-γ and TNF-α in Mtb infected mice. Our data demonstrate for the first time, potential application of MIP as a booster to BCG vaccine for efficient protection against tuberculosis. This could be very cost effective strategy for efficient control of tuberculosis.