The therapeutic role of oral tolerance in dextran sulfate sodium-induced colitis via Th1-Th2 balance and γδ T cells

Epicutaneous Tolerance Induction to a Bystander Antigen Abrogates Colitis and Ileitis in Mice

BACKGROUND

Although inflammatory bowel disease (IBD) is a failure in maintaining tolerance to the intestinal microbiota, few studies have investigated the use of immunologic tolerance as a treatment approach for IBD. We hypothesized that induction of immune tolerance at a distal site could suppress intestinal inflammation through a process of bystander regulation.

METHODS

Epicutaneous tolerance was induced by topical application of ovalbumin (OVA) using a Viaskin patch for 48 hours. In some experiments, a single feed of ovalbumin was used to drive epicutaneous tolerance-induced regulatory T cells (Tregs) to the intestine. The mechanism of tolerance induction was tested using neutralizing antibodies against TGF-β, IL-10, and Treg depletion using Foxp3-DTR mice. The capacity of skin-draining Tregs, or epicutaneous tolerance, to prevent or treat experimental IBD was tested using T-cell transfer colitis, dextran sodium sulfate (DSS) colitis, and ileitis in SAMP-YITFc mice. Weight loss, colonic inflammatory cytokines and histology were assessed.

RESULTS

Epicutaneous exposure to ovalbumin induced systemic immune tolerance by a TGF-β-dependent, but IL-10 and iFoxp3 Treg-independent mechanism. Skin draining Tregs suppressed the development of colitis. Epicutaneous tolerance to a model antigen prevented intestinal inflammation in the dextran sodium sulfate and SAMP-YITFc models and importantly could halt disease in mice already experiencing weight loss in the T-cell transfer model of colitis. This was accompanied by a significant accumulation of LAP and Foxp3 Tregs in the colon.

CONCLUSIONS

This is the first demonstration that epicutaneous tolerance to a model antigen can lead to bystander suppression of inflammation and prevention of disease progression in preclinical models of IBD.

Sodium selenite ameliorates dextran sulfate sodium-induced chronic colitis in mice by decreasing Th1, Th17, and γδT and increasing CD4(+)CD25(+) regulatory T-cell responses

AIM

To assess the effect of sodium selenite on the severity of dextran sulfate sodium (DSS)-induced colitis in C57BL/6 mice.

METHODS

Mice were randomly divided into four groups (n = 10/group): normal group, selenium (Se) group, chronic colitis group, and Se + chronic colitis group. The mice were sacrificed on day 26. Survival rates, clinical symptoms, colon length, and histological changes were determined. The percentages and absolute numbers of immune system cells in the lamina propria lymphocytes (LPL) of the colon, the expression of mRNA in colon tissue, and the concentrations of Th1, Th17, and Treg cytokines in LPL from the large intestine, were measured.

RESULTS

Se significantly ameliorated the symptoms of colitis and histological injury (P < 0.05 each), increasing the proportions of neutrophils and CD4⁺ CD25⁺ T cells (P < 0.05 each) and decreasing the proportions of γδT cells, CD4⁺, CD4⁺CD44⁺, and CD4⁺ CD69⁺ T cells in LPL (P < 0.05 each). Moreover, Se reduced the expression of IL-6, IFN-γ, IL-17A, IL-21, T-bet, and RORγt (P < 0.05 each), but enhanced the expression of IL-10 and Foxp3 (P < 0.05 each).

CONCLUSION

These results suggest that Se protects against DSS-induced chronic colitis perhaps by increasing the number of CD4(+)CD25(+) Tregs that suppress the secretion of proinflammatory cytokines and populations of Th1, Th17, and γδT cells.

Dietary fucoidan of Acaudina molpadioides and its enzymatically degraded fragments could prevent intestinal mucositis induced by chemotherapy in mice

Mucositis is a common problem that results from cancer chemotherapy and is a cause of significant morbidity and occasional mortality.

Immune cell therapy in IBD

The therapeutic landscape of IBD has undergone a dramatic transformation since the advent of biologic therapies, especially TNF inhibitors. However, 30% of patients are primary nonresponders to biologic therapy and secondary failures are frequent. Due to substantial progress in our understanding of the biology of regulatory T cells (Tregs) and in the pathways of homing to the gastrointestinal tract, novel cell-based therapies for IBD have become possible. For example, although a reductionist view, one could envisage IBD as an imbalance between the proinflammatory effectors (such as Th17 cells) and the anti-inflammatory regulators (like Tregs). Here we focus on the development of ex vivo and in vivo approaches to enhance Tregs in the gastrointestinal tract. Specifically, herein we highlight a recently concluded phase 1/2a clinical trial that investigated the safety and efficacy of a single injection of escalating doses of autologous ovalbumin-specific Tregs in patients with active Crohn's disease refractory to conventional therapy. This therapy was well tolerated and demonstrated dose-related efficacy. We also discuss the potential of directing Tregs derived through intranasal as well as epicutaneous immunization to the gastrointestinal tract by enhancing their gut homing signature and their potential to decrease gastrointestinal inflammation. Finally, the strengths and pitfalls of these new therapeutic approaches are discussed as we move forward in this largely uncharted territory.