Intra-colonic administration of the TLR7 agonist R-848 induces an acute local and systemic inflammation in mice

Imidazoquinoline compounds, such as resiquimod (R-848), are well known topically active immune modifiers that bind to toll-like receptor 7 (TLR7). The aim of this study was to characterize the R-848 induced inflammatory response in mice and to validate the response using methyl-prednisolone and anti-TNF antibody. Intra-colonic application of R-848 to BALB/c mice induced a systemic transient elevation of TNF, CXCL1, IL-6, and IL-12p40 and a colonic elevation of cytokines/chemokines and iNOS, without infiltration of immune cells or epithelial destruction. Treatment with methyl-prednisolone or anti-TNF antibody attenuated the systemic (TNF, IL-6, IL-12p40, and CXCL1) and local (colonic TNF and iNOS mRNA expression) response induced by R-848. In summary, intra-colonic administration of R-848 induces an acute systemic and local inflammatory response, which can be attenuated by steroids or anti-TNF antibody. We suggest that the R-848 inflammatory model can be useful in future validation of new drugs for gastrointestinal inflammatory conditions.