Identification of biomarkers for Mycobacterium tuberculosis infection and disease in BCG-vaccinated young children in Southern India

Pediatric tuberculosis (TB) often goes undiagnosed because of the lack of reliable diagnostic methods. With the aim of assessing biomarker(s) that can aid in the diagnosis of TB infection and disease, we investigated 746 Indian children with suspected TB. Whole-blood mRNA from 210 children was examined by dual-color Reverse-Transcriptase Multiple Ligation-dependent Probe-Amplification for the expression of 45 genes and a Bio-Plex assay for the expression of cytokines/chemokines in QuantiFERON supernatants. The study shows that transcription of SEC14L1, GUSB, BPI, CCR7 and TGF beta-1 (all P <= 0.05) was downregulated in TB disease compared with uninfected controls, while transcription of RAB33A was downregulated in TB disease compared with both latent TB (P<0.05) and controls (P<0.01). The transcription of CD4, TGF beta-1 (P<0.01) and the expression of IL-2 (P<0.01) and IL-13 (P<0.05) was upregulated in latent TB compared with that in controls. Using the Least Absolute Shrinkage and Selection Operator (lasso) model, RAB33A alone discriminated between TB disease and latent TB (area under the curve (AUC) 77.5%), whereas a combination of RAB33A, CXCL10, SEC14L1, FOXP3 and TNFRSF1A was effective in discriminating between TB disease and controls (AUC 91.7%). A combination of 11 biomarkers predicted latent TB with moderate discriminatory power (AUC 72.2%). In conclusion, RAB33A is a potential biomarker for TB disease, whereas CD4, TGF beta-1 and IL-2, IL-13 may identify latent TB in children.