Muscle larvae of Trichinella spiralis parasitize the host intestinal epithelium. The mechanisms of exosomes participating in the invasion of T. spiralis muscle larvae are unclear. Hence, the purpose of this study was to explore the effect of exosomes derived from T. spiralis infective larvae (TsExos) on the barrier function of porcine small intestinal epithelial cells (IPEC-J2). First, TsExos were successfully obtained, and their ingestion by epithelial cells was validated. Furthermore, the optimal induction condition was determined by the CCK8 kit, and we found that exposure to 150 μg/mL TsExos for 12/24 h decreased the viability of IPEC-J2 cells by 30%. Based on this outcome, the effects of TsExos on cell biological processes and tight junctions were studied. After coincubation of TsExos and IPEC-J2 cells, the results showed a significant increase in the content of FITC-dextran and in the levels of lactate dehydrogenase (LDH) and reactive oxygen species (ROS). The rate of apoptosis increased by 12.57%, and nuclear pyknosis and nuclear rupture were observed. After the cells were induced by TsExos, the expression of IL-1 was upregulated, but the expression of IL-10, TGF-β, TLR-5, MUC-1 and MUC-2 was downregulated. TsExo induction also led to a decrease in the levels of ZO-1, CLDN-3, and OCLN. In conclusion, TsExos are involved in several cellular biological processes, and they function by disrupting physiological and biochemical processes, hyperactivating innate immunity, and damaging tight junctions.

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The accumulation of unfolded or misfolded proteins in the endoplasmic reticulum can cause an endoplasmic reticulum stress (ERS) response. If ERS continues or cannot be alleviated, it will cause the production of proapoptotic factors and eventually lead to apoptosis. Therefore, this study mainly explored whether Trichinella spiralis Kazal-type serine protease inhibitor (TsKaSPI) contributed to the invasion of intestinal epithelial cells during the infectious stage of T. spiralis by regulating ERS. First, in the T. spiralis infection model, H&E staining was used to analyse the damage to jejunum tissue, a TUNEL assay was used to examine cell apoptosis, and the expression of ERS-related and apoptosis-related molecules was also measured. The results showed that ERS occurred during the intestinal phase of T. spiralis infection, while remission began during the cyclic phase. Then, we selected TsKaSPI, one of the important components of T. spiralis ES antigens, for in vitro experiments. The results showed that TsKaSPI could induce apoptosis in a porcine small intestinal epithelial cell line (IPEC cells) by activating ERS and promote activation of the NF-κB signalling pathway. Inhibition experiments confirmed that the occurrence of ERS was accompanied by the activation of NF-κB, and the two processes regulated each other. Finally, we conducted in vivo experiments and administered TsKaSPI to mice. The results confirmed that TsKaSPI could activate ERS and lead to apoptosis in intestinal epithelial cells. In conclusion, T. spiralis infection and TsKaSPI can promote cell apoptosis by activating the ERS response in intestinal epithelial cells and activate the NF-κB signalling pathway to promote the occurrence and development of inflammation.

In this paper, a robust digital watermarking method against shearing based on orthogonal function system is introduced. The proposed method makes use of the complete generalized orthogonal properties of Haar orthogonal function system to achieve the piece-based orthogonal transform on the image. The significant middle frequently coefficients in the transformation matrix are picked up, based on characteristics of the image visual system and the Haar orthogonal transform. The watermark is adoptively weighed to the middle frequently matrix. The method improves the validity of watermarking and shows excellent advantage against shearing attack. Experimental results show that the Haar orthogonal function system based watermark approach can provide an excellent protection under geometric attacks.

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