Study Transportation of Drugs within Newly Established Murine Colon Organoid Systems

The development of 3D organoids of the small intestine is a tremendous breakthrough in drug development and biological research. However, the development of colonic organoids (i.e., colonoids) is particularly challenging due to a lack of simple, cost-effective protocols for colonoid cultivation. Here, intestinal homogenates are described as a supplement to the culture medium for maintaining and replicating colonic stem cells. Colonoids generated by this cultivation protocol demonstrate substantial proliferation and differentiation (3 months). There is a similarity between cultured colonoids and primary colon tissue regarding structure and functionality. To evaluate the functionality of colonoids, permeability testing is performed with suspensions of 4 and 40 kDa fluorescein isothiocyanate-dextran (FITC-DEX). It is observed that neither can permeate the healthy epithelial barrier. The P-glycoprotein receptor, a vital drug efflux pump mitigating potential drug toxicity, is functionally manipulated, as evidenced by its inhibition function by verapamil and monitoring uptake of Rhodamin 123. In addition, Forskolin treatment which affects chloride transport results in organoid swelling; this confirms the functional expression of the CFTR transporter in the colonoids. This protocol to generate colonoids is promising for high-throughput drug screening, toxicity testing, and oral drug development.

Upregulation of Polymeric Immunoglobulin Receptor Expression by the Heat-Inactivated Potential Probiotic Bifidobacterium bifidum OLB6378 in a Mouse Intestinal Explant Model

We determined whether a potential probiotic bacterium, Bifidobacterium bifidum OLB6378 (BB6378), exerts beneficial effects on the mucosal immune system in a mouse intestinal explant model. The addition of heat-inactivated BB6378 to intestinal explants prepared from embryonic day 18 BALB/c mice increased the expression of polymeric immunoglobulin receptor (pIgR) mRNA by two- to fivefold. These effects were observed on ileal and colonic explants but not on jejunal explants, suggesting that the BB6378-induced pIgR upregulation is site-specific within the mouse intestine. The upregulation of pIgR protein expression in colonic explants was also detected after 24 h of culture. The results of DNA microarray analysis of ileal and colonic samples indicated that BB6378 increased the gene expression of interleukin (IL)-1α and IL-1β, and IL-1α content in colonic explants was significantly increased after 20 h of culture with BB6378. We then examined the involvement of endogenously induced IL-1α in pIgR mRNA upregulation by using IL-1α knockout (KO) mice. Contrary to our expectations, pIgR mRNA expression was equally upregulated by BB6378 in colonic explants from BALB/c and IL-1α KO mice. Conversely, we examined the involvement of Toll-like receptors in pIgR mRNA upregulation by using MyD88 KO mice. The upregulation of pIgR was completely suppressed in the explants derived from MyD88 KO mice. Taken together, we conclude that in a mouse intestinal explant model, the heat-inactivated potential probiotic BB6378 increases intestinal pIgR expression in a site-specific manner and that the upregulation of pIgR could be explained by a direct microbial effect on the epithelium via Toll-like receptors.

Reduced production of polymeric immunoglobulin receptor in murine dextran sodium sulfate-induced colitis

Polymeric immunoglobulin receptor (pIgR) plays an intrinsic role in protecting the intestinal tract from invading pathogens. In the present study, we observed a decrease in pIgR in colon lysate from mice with dextran sodium sulfate (DSS) colitis. A decrease in pIgR was detected in both mRNA and protein levels. Histologic examinations revealed marked destruction of intestinal epithelial cells (IECs), and only a small number of regenerating IECs expressed pIgR. These results suggest that the decrease in pIgR was due to the destruction of IECs. Because activation of toll-like receptor 3 slows the progression of DSS colitis, we injected polyriboinosinic: polyribocytidylic acid (poly I:C) intraperitoneally and observed the correlation between pIgR level and severity of DSS colitis. Poly I:C markedly decreased progression of DSS colitis, and pIgR levels significantly recovered. Furthermore, we found that expressions of IFN-γ and TNF-α were higher in DSS colitis. These results indicate that the decrease in pIgR was not compensated for by increased expression of these cytokines. In sum, our findings show that pIgR levels vary according to the severity of DSS colitis and that these changes might be useful as a biomarker of the severity of inflammatory bowel disease.