Prognostic utility of immune biomarkers for identifying individuals at risk of unfavourable treatment outcomes in pulmonary tuberculosis

Introduction Tuberculosis remains a major global health challenge, with many patients expe- riencing unfavourable treatment outcomes despite standard therapy. Host immune biomarkers, including cytokines, chemokines, and matrix metalloproteinases (MMPs), have shown promise in predicting disease severity and treatment response, but require validation across independent cohorts. Methods We validated previously identified immune biomarkers using baseline plasma samples from a nested case–control cohort within the RePORT India consortium (cases: n=74; controls: n=161). Cytokines (IL-2, IFN-γ, TNF-α, IL-6, IL-1β, IL-10, IL-17A, and GM-CSF), chemokines (CCL2, CCL3, CCL4, CXCL1, CXCL8, and CXCL10), and matrix metalloproteinases (MMP-1, MMP-2, MMP-7, and MMP-9) were quantified using multiplex ELISA on the Luminex platform. Statistical analyses included group comparisons, ROC analysis, logistic regression, random forest modelling, princi- pal component analysis, and stability selection to identify optimal biomarker combinations. Results Elevated levels of IL-2, IFN-γ, TNF-α, IL-6, CCL2, CXCL8, CXCL10, MMP-2, MMP-7, and MMP-9 were associated with unfavourable out- comes. IL-2, CXCL8, CCL2, and MMP-2 showed strong individual predictive performance (AUC ≥0.80). Multivariable analysis identified CCL2, CXCL8, and CXCL10 as significant predictors of poor outcomes. A combined biomarker panel comprising CXCL8, MMP-2, and CCL2 demonstrated excellent predictive accu- racy (AUC ~0.90), with sensitivity ranging from 89% to 98% and specificity ranging from 80% to 90%, depending on the biomarker combination and the selected ROC cut-off. Discussion These findings validate key immune biomarkers and support a multi- marker host biomarker panel for early risk stratification and personalized TB management.