Inflammation induced by influenza virus impairs innate control of human pneumococcal carriage

Simon P. Jochems; Fernando Marcon; Beatriz F. Carniel; Mark Holloway; Elena Mitsi; Emma Smith; Jenna F. Gritzfeld; Carla Solórzano; Jesús Reiné; Sherin Pojar; Elissavet Nikolaou; Esther L. German; Angie Hyder-Wright; Helen Hill; Caz Hales; Wouter A.A de Steenhuijsen Piters; Debby Bogaert; Hugh Adler; Seher Zaidi; Victoria Connor; Jamie Rylance; Helder I. Nakaya; Daniela M. Ferreira

LAIV administration from a subset of subjects. We confirmed that opsonophagocytic killing of Spn 124 by blood neutrophils was decreased following LAIV (Fig 2b, p < 0.05 ). This effect could be 125 mimicked by the addition of TNF-α, but not IP-10, to neutrophils from healthy donors in vitro, 126 decreasing killing capacity in a dose-dependent manner (Fig 2c,d) . Nanostring expression analysis 127 of 594 genes revealed 10 differentially expressed genes in blood neutrophils 3 days post LAIV 128 (Table S2) . Among those were MAP4K2 (3.2-fold increase, p=3.2x10 -5 ), which acts on the TNF-α 129 signal transduction pathway 33 , and TIGIT (3.6-fold increase, p=0.008, Fig 2e) . TIGIT expression 130 levels also negatively correlated with neutrophil killing capacity (r=-0.73, p=0.02, Fig 2f) . TIGIT is 131 an "immune checkpoint" protein, which has been described to promote Treg cell function 34 , but its 132 expression on neutrophils has not been previously appreciated. Incubation of whole blood with 133 recombinant TNF-α increased TIGIT levels on neutrophil surface within 30 minutes in a dose-134 dependent manner (Fig 2g) .