Cutting Edge: TNF Is Essential for Mycobacteria-Induced MINCLE Expression, Macrophage Activation, and Th17 Adjuvanticity

TNF blockade is a successful treatment for human autoimmune disorders like rheumatoid arthritis and inflammatory bowel disease yet increases susceptibility to tuberculosis and other infections. The C-type lectin receptors (CLR) MINCLE, MCL, and DECTIN-2 are expressed on myeloid cells and sense mycobacterial cell wall glycolipids. In this study, we show that TNF is sufficient to upregulate MINCLE, MCL, and DECTIN-2 in macrophages. TNF signaling through TNFR1 p55 was required for upregulation of these CLR and for cytokine secretion in macrophages stimulated with the MINCLE ligand trehalose-6,6-dibehenate or infected with Mycobacterium bovis bacillus Calmette-Guérin. The Th17 response to immunization with the MINCLE-dependent adjuvant trehalose-6,6-dibehenate was specifically abrogated in TNF-deficient mice and strongly attenuated by TNF blockade with etanercept. Together, interference with production or signaling of TNF antagonized the expression of DECTIN-2 family CLR, thwarting vaccine responses and possibly increasing infection risk.