Mo1699 Denosumab: A Monoclonal Antibody to Receptor Activator of Nuclear Factor-Kappa B Ligand (RANKL) Decreases Experimental Colitis

Abstract

The gastrointestinal microbial communities of C57BL/6 mice between Taconic Farms (Tac) and Jackson Laboratory (Jax) are highly variable; most notably, only the Tac mice are colonized with segmented filamentous bacteria (SFB), a potent inducer of proinflammatory TH17 cells. To examine whether Jax and Tac mice have a different intestinal microbiome and respond differently to H. pylori (Hp) infection, C57BL/6 mice from Tac and Jax were dosed with Hp PMSS1. As measured by Illumina sequencing, OTUs in fecal microbiomes were richer in Tac than Jax mice (p<0.01); the ratio of Bacteriodetes to Firmicutes, two predominant phyla, were 1.86 for Jax but 0.33 for Tac mice. In addition, the results obtained by qPCR demonstrated that colonization status of 5 mucosa-associated species ASF356, ASF361, ASF457, ASF500, ASF519 (members of altered schaedler flora) in the stomachs of the control mice from the 2 vendors were comparable, while there were significantly lower levels of ASF457 and ASF519 but higher levels of ASF361 and ASF500 in the ceca of control Jax mice compared to the Tac counterparts (P<0.01). By 16 weeks-post-inoculation, there were significantly lower levels of gastric and cecal ASF361, cecal ASF457, ASF500 and ASF519, but higher levels of cecal ASF356 in the infected Jax mice compared to their controls (P<0.01). Hp infection in Tac mice also increased SFB levels in the large intestine but did not influence ileal SFB levels compared to the controls. In contrast, Hp infection was only associated with higher levels of cecal ASF356 in the infected Tac mice compared to the sham controls (P<0.0001). Interestingly, Hp infection significantly altered fecal microbial compositions of Tac mice with an increase of the class Bacilli and a decrease in the classes Clostridia and Bacteroidia but this was not noted in Jax mice. Hp colonization levels and mRNA expression of gastric Il-1β, Il-17A, and RegIIIγwere significantly lower in Tac compared to Jax mice (P<0.05). In contrast, mRNA levels of gastric Inf-γ, Tnf-α, and Foxp-3 were comparable between the infected Jax and Tac groups. There were no significant differences in gastric pathology including inflammation, epithelial defects, oxyntic atrophy, hyperplasia, and dysplasia between the infected Jax and Tac groups, except for mucus metaplasia that was more severe in the infected Tac mice vs. the infected Jax mice (P<0.05). Our data indicate that the overall gastrointestinal microbiomes in Tac mice are more diverse and prone to Hp perturbation compared to Jax mice, while there is more profound Hp-associated change in colonization levels of the 5 mucosa-associated ASF species in Jax mice than Tac mice. Long-term clinical effects of the different responses in the microbiome and inflammation-associated mediators to Hp infection between Jax and Tac mice needs further study.