Differential expression of an alternative splice variant of IL-12Rβ1 impacts early dissemination in the mouse and associates with disease outcome in both mouse and humans exposed to tuberculosis

Abstract

Experimental mouse models of TB suggest that early events in the lung impact immunity. Early events in the human lung in response to TB are difficult to probe and their impact on disease outcome is unknown. We have shown in mouse that a secreted alternatively-spliced variant of IL-12Rβ1, lacking the transmembrane domain and termed ΔTM-IL-12Rβ1, promotes dendritic cell migration to the draining lymph node, augments T cell activation and limits dissemination of M. tuberculosis (Mtb). We show here that CBA/J and C3H/HeJ mice (both highly susceptible to Mtb) express higher levels of ΔTM-IL-12Rβ1 than resistant C57BL6 mice and limit early dissemination of Mtb from the lungs. Both CD11c+ cells and T cells express ΔTM-IL-12Rβ1 in humans, and mice unable to make ΔTM-IL-12Rβ1 in either CD4 or CD11c expressing cells permit early dissemination from the lung. Analysis of publically available blood transcriptomes indicates that pulmonary TB is associated with high ΔTM-IL-12Rβ1 expression and that of all IL-12 related signals, the ΔTM-IL-12Rβ1 signal best predicts active disease. ΔTM-IL-12Rβ1 expression reflects the heterogeneity of latent TB infection and has the capacity to discriminate between latent and active disease. In a new Chinese TB patient cohort, ΔTM-IL-12Rβ1 effectively differentiates TB from latent TB, healthy controls and pneumonia patients. Finally, ΔTM-IL-12Rβ1 expression drops in drug-treated individuals in the UK and China where infection pressure is low. We propose that ΔTM-IL-12Rβ1 regulates early dissemination from the lung and that it has diagnostic potential and provides mechanistic insights into human TB.