Dynamic Changes in Pro- and Anti-Inflammatory Cytokine Profiles and Gamma Interferon Receptor Signaling Integrity Correlate with Tuberculosis Disease Activity and Response to Curative Treatment

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Abstract
Pro- and anti-inflammatory cytokines and their signaling pathways play key roles in protection from and pathogenesis of mycobacterial infection, and their balance and dynamic changes may control or predict clinical outcome. Peripheral blood cells' capacity to produce proinflammatory (tumor necrosis factor alpha [TNF-α], interleukin-12/23p40 [IL-12/23p40], and gamma interferon [IFN-γ]) and anti-inflammatory (IL-10) cytokines in response toMycobacterium tuberculosisor unrelated stimuli (lipopolysaccharide, phytohemagglutinin) was studied in 93 pulmonary tuberculosis (TB) patients and 127 healthy controls from Indonesia. Their cells' ability to respond to IFN-γ was examined to investigate whetherM. tuberculosisinfection can also inhibit IFN-γ receptor (IFN-γR) signaling. Although there was interindividual variability in the observed responses, the overall results revealed thatM. tuberculosis-induced TNF-α and IFN-γ levels showed opposite trends. Whereas TNF-α production was higher in active-TB patients than in controls, IFN-γ production was strongly depressed during active TB, correlated inversely with TB disease severity, and increased during therapy. By contrast, mitogen-induced IFN-γ production, although lower in patients than in controls, did not change during treatment, suggesting anM. tuberculosis-specific and reversible component in the depression of IFN-γ. Depressed IFN-γ production was not due to decreased IL-12/IL-23 production. Importantly, IFN-γ-inducible responses were also significantly depressed during active TB and normalized during treatment, revealing disease activity-related and reversible impairment in IFN-γR signaling in TB. Finally, IFN-γ/IL-10 ratios significantly correlated with TB cure. Taken together, these results show thatM. tuberculosis-specific stimulation of IFN-γ (but not TNF-α) production and IFN-γR signaling are significantly depressed in active TB, correlate with TB disease severity and activity, and normalize during microbiological TB cure. The depression of both IFN-γ production and IFN-γR signaling may synergize in contributing to defective host control in active TB.