Another study investigated the expression of NLRs in middle-ear tissues of humans and animals [46], comparing NOD2/RICK-dependent regulation of β-defensin 2 in middle-ear fluid of pediatric AOM patients, human middle ear epithelial cells, and C57BL/6 and NOD2−/− (B6.129S1-Nod2tm1Flv) mice. The gene discussed is NOD2; the disease is infectious otitis media.