However, Tweak expression was markedly reduced in PBS-treated M1R-deficient mice (1.0 ± 0.09 vs. 0.36 ± 0.07 fold respectively, p < 0.001); this decreased further following treatment with AOM (0.11 ± 0.03 fold, p < 0.01). This evidence concerns the gene TNFSF12 and infectious otitis media.