Induced and spontaneous colitis mouse models reveal complex interactions between IL-10 and IL-12/IL-23 pathways.

Crohn's disease (CD) and ulcerative colitis (UC) are the two major forms of inflammatory bowel disease (IBD). These idiopathic and chronic diseases result from inflammation of the gastrointestinal tract and are mainly mediated by the immune system. Genome wide association studies link genes of the IL-12 and IL-23 biology to both CD and UC susceptibility. IL-12 and IL-23 cytokines share a functional subunit, p40, and their respective receptors also share a functional subunit, IL-12Rß1. However, clinical trials targeting p40, and thus inhibiting both IL-12 and IL-23 pathways, provided mitigated effects on IBD, suggesting context dependent effects for each cytokine. In addition to IL-12 and IL-23, genetic deficiencies in IL-10 also result in severe IBD pathology. We generated various mouse models to determine how IL-12 or IL-23 interacts with IL-10 in IBD pathology. Whereas defects in both IL-10 and IL-12R do not impact the severity of the Dextran Sulfate Sodium (DSS)-induced colitis, combined deficiencies in both IL-10 and IL-23R aggravate the disease. In contrast to DSS-induced colitis, defects in IL-12R and IL-23R both protect from the spontaneous colitis observed in IL10-/- mice. Together, these studies exemplify the complexity of genetic and environmental interactions for identifying biological pathways predictive of pathological inflammatory processes.

Specific targeting of the IL-23 receptor, using a novel small peptide noncompetitive antagonist, decreases the inflammatory response.

IL-23 is part of the IL-12 family of cytokines and is composed of the p19 subunit specific to IL-23 and the p40 subunit shared with IL-12. IL-23 specifically contributes to the inflammatory process of multiple chronic inflammatory autoimmune disorders, including psoriasis, multiple sclerosis, inflammatory bowel disease, and rheumatoid arthritis. So far, one antibody targeting the shared p40 subunit of IL-12 and IL-23, Ustekinumab, is approved clinically to treat psoriasis. However, there are no treatments inhibiting specifically the IL-23 proinflammatory response. We have developed small IL-23R-specific antagonists by designing all D-peptides arising from flexible regions of IL-23R. Of these peptides, we selected 2305 (teeeqqly), since in addition to its soluble properties, it inhibited IL-23-induced STAT3 phosphorylation in spleen cells. Peptide 2305 specifically binds to IL-23R/IL-12Rß1-expressing HEK-293 cells and not to cells devoid of the receptor. Peptide 2305 showed functional selectivity by modulating IL-23-induced gene expression in IL-23R/IL-12Rß1-expressing cells and in Jurkat cells; 2305 does not inhibit IL-12-induced cytokine expression in IL-12Rß-IL-12Rß2-HEK-293 cells. Finally, compared with anti-p40 treatment, 2305 effectively and selectively inhibits IL-23-induced inflammation in three in vivo mouse models: IL-23-induced ear inflammation, anti-CD40-induced systemic inflammatory response, and collagen-induced arthritis. We, hereby, describe the discovery and characterization of a potent IL-23R small-peptide modulator, 2305 (teeeqqly), that is effective in vivo. 2305 may be more convenient, less cumbersome, less costly, and most importantly, more specific than current biologics for the treatment of inflammatory conditions, and conceivably complement the actual therapies for these chronic and debilitating inflammatory diseases.

The dichotomous pattern of IL-12r and IL-23R expression elucidates the role of IL-12 and IL-23 in inflammation.

IL-12 and IL-23 cytokines respectively drive Th1 and Th17 type responses. Yet, little is known regarding the biology of these receptors. As the IL-12 and IL-23 receptors share a common subunit, it has been assumed that these receptors are co-expressed. Surprisingly, we find that the expression of each of these receptors is restricted to specific cell types, in both mouse and human. Indeed, although IL-12Rß2 is expressed by NK cells and a subset of γδ T cells, the expression of IL-23R is restricted to specific T cell subsets, a small number of B cells and innate lymphoid cells. By exploiting an IL-12- and IL-23-dependent mouse model of innate inflammation, we demonstrate an intricate interplay between IL-12Rß2 NK cells and IL-23R innate lymphoid cells with respectively dominant roles in the regulation of systemic versus local inflammatory responses. Together, these findings support an unforeseen lineage-specific dichotomy in the in vivo role of both the IL-12 and IL-23 pathways in pathological inflammatory states, which may allow more accurate dissection of the roles of these receptors in chronic inflammatory diseases in humans.

Hijacking hepatitis C viral replication with a non-coding replicative RNA.

The current treatments used against RNA viruses have a limited efficacy and are often hampered by the induction of side-effects. The specific delivery of antiviral proteins in infected cells should increase their efficiency and reduce their impact on healthy cells. Here, we describe the development of a new approach which takes advantage of the viral replication machinery to specifically target the antiviral protein expression to the infected cells. The strategy is based on the delivery of a non-coding (-)RNA carrying the structures required for the binding of the viral replication complex and the complementary sequence of an antiviral gene. The viral replication complex replicates the (-)RNA similarly to the viral genome to give a coding (+)RNA from which the antiviral protein will be expressed. As non-infected cells do not express the replication complex, this specific machinery can be used to target virus-infected cells without affecting healthy cells. We show that this approach can be successfully applied to the hepatitis C virus. In both replicon-harboring cells (genotype 1b) and JFH-1 infected cells (genotype 2a), nrRNAs induced a strong decrease in genomic RNA and viral protein NS5A. These effects were correlated with a strong activation of several interferon-stimulating genes.