The integrity and normal function of the small intestinal epithelium depends critically on the rapid renewal of epithelial cells from basal stem cells. The intensive proliferation that fuels this self-renewal process is confined to the intestinal crypts. Establishment of suitable protocols for crypt isolation and culture is pivotal for the studies of intestinal self-renewal mechanisms. In this study, chicken small intestinal crypts were isolated, purified, and further cultured in a Matrigel 3-D culture system. The growth factor concentration assay on the fourth d of culture showed that Group C (50 ng/mL epidermal growth factor (EGF), 100 ng/mL Noggin, and 500 ng/mL R-spondin 1) supplement in culture medium could significantly enlarge the diameter of organoids when compared with Group A (5 ng/mL EGF, 10 ng/mL Noggin, 50 ng/mL, and R-spondin 1) and Group B (10 ng/mL EGF, 20 ng/mL Noggin, and 100 ng/mL R-spondin 1) by 188.4% (P = 0.026) and 176.9% (P = 0.034), respectively. Transmission electron microscopy, neutral red staining, and 5-ethynyl-2΄-deoxyuridine incorporation demonstrated the integrated structure, high viability, and proliferative activity in cultured chicken intestinal organoids. In addition, intestinal stem cell marker genes (Olfm4, Znrf3, Hopx, and Lgr5) also could be detected in cultured intestinal organoids. Furthermore, CHIR99021 (a glycogen synthase kinase 3β inhibitor) could enhance the expression of Olfm4, Znrf3, Hopx, and Lgr5 by 750% (P = 0.001), 467% (P < 0.001), 450% (P < 0.001), and 333% (P = 0.008), respectively, indicating the responsiveness of the cultured chicken intestinal organoids to exogenous stimulus. This study modified a murine culture model and optimized it to provide a chicken intestinal organoid model for use as a physiological or pathological research platform in vitro.

Enriched melatonin (MEL) has been found in the mammalian intestine and has been recently demonstrated to alleviate rodent colitis. In this study, the effect of MEL on lipopolysaccharide (LPS)-induced intestinal inflammations was investigated in new chicken hatchlings. The chicks were fed with a diet supplemented with MEL (12.5 mg/day) from D1 to D10. Meanwhile, the chicks in the LPS or MEL + LPS groups were injected with LPS (10 mg/kg BW, i.p.) at D10. LPS treatment for 6 h increased the expression of IL-6, IL-4, caspase-3 mRNAs and TUNEL-positive cell populations, but decreased populations of the goblet and PCNA+ cells, IgA production and the expression of MUC2 mRNA in the duodenum. Compared with the LPS group, MEL pre-feeding alleviated duodenal inflammation and decreased the expression of TNF-α mRNAs by 23.6% (P = 0.004), IL-6 mRNAs by 69.4% (P = 0.001), IL-4 mRNAs by 4.1% (P = 0.824) and caspase-3 mRNAs by 45.8% (P < 0.001). Conversely, MEL pre-feeding attenuated the LPS-induced changes of IgA production by 161.6% (P = 0.013) and PCNA+ cell populations by 172.1% (P < 0.001) in the duodenum. TLR4 mRNA was also up-regulated by LPS treatment but down-regulated by MEL pre-feeding. In conclusion, dietary MEL could attenuate LPS-induced chick duodenal inflammation by down-regulating the expression of inflammatory cytokines, promoting epithelial cell proliferation, improving the immunological barrier and inhibiting epithelial apoptosis via the mediation of TLR4.

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