Porcine epidemic diarrhea virus (PEDV) invades porcine intestinal epithelial cells (IECs) and causes diarrhea and dehydration in pigs. In the present study, we showed a suppression of PEDV infection in porcine jejunum intestinal epithelial cells (IPEC-J2) by an increase in autophagy. Autophagy was activated by rapamycin at a dose that does not affect cell viability and tight junction permeability. The induction of autophagy was examined by LC3I/LC3II conversion. To confirm the autophagic-flux (entire autophagy pathway), autophagolysosomes were examined by an immunofluorescence assay. Pre-treatment with rapamycin significantly restricted not only a 1 h infection but also a longer infection (24 h) with PEDV, while this effect disappeared when autophagy was blocked. Co-localization of PEDV and autophagosomes suggests that PEDV could be a target of autophagy. Moreover, alleviation of PEDV-induced cell death in IPEC-J2 cells pretreated with rapamycin demonstrates a protective effect of rapamycin against PEDV-induced epithelial cell death. Collectively, the present study suggests an early prevention against PEDV infection in IPEC-J2 cells via autophagy that might be an effective strategy for the restriction of PEDV, and opens up the possibility of the use of rapamycin in vivo as an effective prophylactic and prevention treatment.

Intestinal barrier is the first line of defense inside the body and comprises intercellular tight junction (TJ) proteins that regulate paracellular permeability. Deoxynivalenol (DON), a fungal metabolite often found in the contaminated food of domestic animals, is known to impair intestinal barrier function and may be involved in intestinal inflammation. Unlike in humans and mice, the importance of Toll-like receptor (TLR) 2 expressed in porcine intestinal epithelial cells is largely unclear. Therefore, the aim of the present study was to investigate whether TLR2 stimulation enhances intestinal barrier function and protects against DON exposure. We found that the cells treated with TLR2 ligands decreased the epithelial barrier permeability and enhanced TJ protein expression in intestinal porcine epithelial cells (IPEC-J2). In addition, pretreatment with TLR2 ligand, including Pam3CSK4 (PCSK) and lipoteichoic acid from Bacillus subtilis, prevented DON-induced barrier dysfunction by increasing the expression of TJ proteins via the PI3K-Akt-dependent pathway. It is likely that the DON-disrupted intestinal barrier caused biological changes of immune cells in the lamina propria. Thus, we conducted co-culture of differentiated IPEC-J2 cells in the upper well together with peripheral blood mononuclear cells in the bottom well and found that apical TLR2 stimulation of IPEC-J2 cells could alleviate the reduction in cell survival and proliferation of immune cells. Conclusively, TLR2 signaling on intestinal epithelial cells may enhance intestinal barrier function and prevent DON-induced barrier dysfunction of epithelial cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-016-0309-1) contains supplementary material, which is available to authorized users.

Cancer stem cells (CSCs) with self-renewal abilities endorse cellular heterogeneity, resulting in metastasis and recurrence. However, there are no promising therapeutics directed against CSCs. Herein, we found that miR-503-3p inhibited tumor growth via the regulation of CSC proliferation and self-renewal. miR-503-3p, isolated from human adipose stem cell- (ASC-) derived exosomes, suppressed initiation and progression of CSCs as determined by anchorage-dependent (colony formation) and anchorage-independent (tumorsphere formation) assays. The expression of pluripotency genes was significantly decreased in miR-503-3p-treated CSCs. Furthermore, xenografts, which received miR-503-3p, exhibited remarkably reduced tumor growth in vivo. Thus, miR-503-3p may function as a stemness-attenuating factor via cell-to-cell communications.