5, 18-21 In particular, dnTGFβRII IL-12p40 knockouts, lacking the proinflammatory cytokines IL-12 and IL-23, have no biliary disease.7 IL-12 is a major cytokine involved in prototype Th1 responses and plays a role in both innate and adaptive immunity.22 A genomewide association analysis of DNA samples from 536 patients with PBC and 1,536 controls revealed significant associations between PBC and common genetic variants at IL12A locus (encoding p35 subunit) and IL12RB2 (encoding IL-12 receptor β2) locus, suggesting that the IL-12 signaling pathway is relevant to the pathophysiology of PBC.16 A case report of

biliary cirrhosis in an this website IL-12 deficiency child further suggests that the alteration of IL-12 immunomodulatory signaling is critical to the pathogenesis of PBC.23 We demonstrate

herein that, similar to IL-12p40−/−dnTGFβRII mice, the IL-12p35−/−dnTGFβRII mice had significantly milder portal inflammation at 12 weeks compared to dnTGFβRII mice. Because the learn more presence of the proinflammatory IL-23 alone without IL-12, as in the case of the p35−/− mice, is not sufficient to cause early onset of portal inflammation in dnTGFβRII mice, this suggests that IL-12 plays a dominant role in portal inflammation. However, in the p35−/− mice the IL-12 deficiency in the presence of IL-23 but absence of IL-35 did not prevent dnTGFβRII biliary disease at 24 weeks (Fig. 1), suggesting that the pathological role of IL-23 can be enhanced by the deficiency of IL-35 related Treg functions. Unexpectedly, the absence of both IL-12 and IL-35 resulted in a strikingly high frequency (>50%) of liver fibrosis in the IL-12p35−/−dnTGFβRII mice (Fig. 3), which has not been seen in any other mouse models of PBC. Because IL-35 is expressed only by Tregs, whereas

O-methylated flavonoid dnTGFβRII mice clearly lack the ability to regulate the immune response by way of TGFβ, an important mechanism of Treg-mediated tolerance, adding an IL-35 deficiency might cripple the Treg mechanisms further; it points to a role for Treg activity in control of liver pathogenesis including fibrosis. In PBC, a predominance of prototype Th1 cytokines and Th1 cells have been reported, and the Th1 response has been highly correlated with the degree of bile duct destruction.24-26 Furthermore, a significant decline of Th2 response has been reported during the late stage of PBC.27 Similar observations have also been reported in other organ-specific autoimmune diseases in which a Th2-type response prevented tissue damage.28, 29 However, the role of the newer IL-12 family cytokines in PBC is not yet clear. We should note that the cell isolation techniques used herein are similar to our previous work; we avoided enzymatic digestion because NK1.1 and the DX5 marker are significantly down-regulated after isolation using enzymatic digestion.