Pathological Role of Large Intestinal IL-12p40 for the Induction of Th2-Type Allergic Diarrhea

Abstract

IL-12 consists of two disulfide-linked subunits, p40 and p35, that form functionally active heterodimers for the induction of Th1 cells. In contrast to IL-12 heterodimers, p40 monomers and homodimers possess inhibitory effects on Th1 cells leading to the creation of a Th2 environment. Although it has been shown that IL-12p40 acts as antagonist of IL-12p70 in vitro, no evidence is currently available whether IL-12p40 is functional in vivo. We now report that IL12p40 plays an important pathological role in an intestinal allergic disease. A high expression of IL12p40 protein was demonstrated in epithelial cells, dendritic cells, and macrophages in large but not small intestine of allergic diarrhea-induced mice. Interestingly, neutralization with anti-IL-12p40 mAbs reduced the incidence and delayed the onset of disease development. Lower levels of ovalbumin (OVA)-specific IgE Abs in serum were detected in anti-IL12p40 mAb-treated mice than in control Ab-treated mice. The secretion of Th2 cytokines and eotaxin by the mononuclear cells isolated from the large intestine of anti-IL-12p40 mAb-treated mice was significantly decreased. Finally, the removal of the IL-12p40 gene resulted in complete inhibition of disease development. These results show that over-expression of IL-12p40 is an important contributing factor for the generation of the dominant Th2-type environment in the large intestine of mice with allergic diarrhea.

Nasal IL-12p70 DNA Prevents and Treats Intestinal Allergic Diarrhea

“…IL-12p40 transgenic mice have been shown to be more susceptible to the malaria infection due to the reduced Th1 responses (14). These findings, together with our previous observation that large intestinal IL12p40 contributes to the generation of Th2 cell-mediated allergic disease, suggest that the mucosal IL-12 balance between p70 and p40 might be a key regulator for the Th1 and Th2 networks associated with the mucosal immune compartment (7). Because it is located on chromosome 5q with its allergy-associated cytokine gene cluster of IL-4, IL-5, and IL-13 (15), the IL-12p40 gene in particular can be considered as one of the potent regulators of Th2 cell induction.…”

“…For the induction of allergic diarrhea, we used a previously established protocol (4,7). Briefly, on the first day of the experiment (day 0), mice were primed by s.c. injection of 1 mg of OVA in CFA (Difco).…”

“…To isolate mononuclear cells from small and large intestines, we used an enzymatic dissociation method (4,7). Mononuclear cells were incubated in 96-well nitrocellulose plates (Millititer HA; Millipore) precoated with OVA (1 mg/ml) for 4 h at 37°C with 5% CO 2 in air.…”

“…Intestinal allergic inflammation was also induced in the small intestine by the eosinophils, eotaxin, and IL-5 associated with a pathologic Th2 environment in mice treated with OVA in entericcoated beads (6). Our most recent study elucidated the molecular and cellular pathologic mechanisms underlying Th2 cell-mediated intestinal allergic disease by showing that locally produced IL12p40 contributes to the generation of a dominant Th2-type environment in the large intestine of mice with allergic diarrhea (7).…”

Tetragenococcus halophilus MN45 Isolated from Miso Inhibits IgE Production

“…Next, we examined the suppressive effect of MN45 on IgE production using PP cells and splenocytes from OVAinduced allergic diarrhea mice. OVA-induced allergic diarrhea is classified as a type-1 allergy resulting from excessive serum IgE production through the Th2 predominant response (Hino et al, 2004;Kweon et al, 2000). We examined the improvement of Th1/Th2 balance and the suppression of IgE production using PP cells and splenocytes of these mice (Fig.…”