Our previous studies demonstrated that matrine directly acts on the replication process of porcine reproductive and respiratory syndrome virus (PRRSV). Matrine inhibits viral replication and is also associated with the NF-κB signalling pathway. These results suggest that matrine has antiviral and anti-inflammatory effects. However, the specific anti-inflammatory mechanism of matrine is still unclear. In this study, we investigated the anti-IL-1β mechanism of matrine, as IL-1β is a major inflammatory cytokine, in porcine alveolar macrophages (PAMs) stimulated with 4 μg PRRSV 5′-untranslated region (UTR) RNA and 1 μg/mL LPS. After 5′UTR RNA and LPS co-stimulation of PAMs for 12 h, the expression of IL-1β, IL-6, IL-8 and TNF-α was significantly increased. The results also showed that co-stimulation induced the expression of MyD88, and activated the NF-κB signalling pathway and NLRP3 inflammasome. Furthermore, matrine treatment downregulated MyD88, NLRP3 and caspase-1 expression, inhibited ASC speck formation, suppressed IκBα phosphorylation, and interfered with the translocation of NF-κB from the cytoplasm to the nucleus. These results suggest that matrine plays an important role in PAMs co-stimulated with PRRSV 5′UTR RNA and LPS via its effect on NF-κB and the NLRP3 inflammasome. These findings lay the foundation for the exploration of the clinical application of matrine in PRRSV disease.

Background: Porcine circovirus type 2 (PCV2) is an immunosuppressive pathogen with high prevalence rate in pig farms. It has caused serious economic losses to the global pig industry. Due to the rapid mutation of PCV2 strain and co-infection of different genotypes, vaccination could not eradicate the infection of PCV2. It is necessary to screen and develop effective new compounds and explore their anti-apoptotic mechanism. The 13 natural compounds were purchased, with a clear plant origin, chemical structure and content and specific biological activities. Results: The maximum no-cytotoxic concentration (MNTC) and 50% cytotoxic concentration (CC₅₀) of 13 tested compounds were obtained by the cytopathologic effect (CPE) assay and (3-(4,5-dimethyithiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method in PK-15 cells. The results of qPCR and Western blot showed that, compared with the PCV2 infected group, the expression of Cap in Paeonol (0.4 mg/mL and 0.2 mg/mL), Cepharanthine (0.003 mg/mL, 0.0015 mg/mL and 0.00075 mg/mL) and Curcumin (0.02 mg/mL, 0.001 mg/mL and 0.005 mg/mL) treated groups were significantly lowered in a dose-dependent manner. The results of Annexin V-FITC/PI, JC-1, Western blot and ROS analysis showed that the expression of cleaved caspase-3 and Bax were up-regulated Bcl-2 was down-regulated in Cepharanthine or Curcumin treated groups, while ROS and MMP value were decreased at different degrees and the apoptosis rate was reduced. In this study, Ribavirin was used as a positive control. Conclusions: Paeonol, Cepharanthine and Curcumin have significant antiviral effect. And the PCV2-induced Mitochondrial apoptosis was mainly remitted by Cepharanthine and Curcumin.

Background: Encephalomyocarditis virus (EMCV) infection can cause reproductive failure in sows and acute myocarditis and sudden death in piglets. It has caused huge economic losses to the global pig industry and that is why it is necessary to develop effective new treatment compounds. Zedoary turmeric oil has been used for treating myocarditis. Curcumol extracted from the roots of curcuma is one of the main active ingredient of zedoary turmeric oil. The anti-EMCV activity of curcumol along with the molecular mechanisms involved with a focus on IFN-β signaling pathway was investigated in this study. Method: 3-(4,5-dimethyithiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the maximum non-toxic concentration (MNTC), 50% cytotoxic concentration (CC₅₀), maximum inhibition rate (MIR) and 50% effective concentration (EC₅₀) against EMCV. Through EMCV load, the anti-viral effect of curcumol was quantitatively determined using real-time quantitative PCR (qPCR). The effect of curcumol on the expression of IFN-β was investigated using real-time quantitative PCR and ELISA. Western blot was used to determine the amounts of MDA5, MAVS, TANK, IRF3 and P-IRF3 proteins in human embryonic kidney 293 T (HEK-293 T) cells infected with EMCV. Results: The results of MTT showed that compared with the ribavirin positive control group, the maximum inhibition ratio (MIR) of curcumol was greater but the selection index (SI) value was much smaller than that of ribavirin. The results of qPCR showed that curcumol and ribavirin significantly reduced the replication of EMCV in HEK-293 T cells. The curcumol (0.025 mg/mL) treatment has significantly increased IFN-β mRNA expression in the EMCV-infected HEK-293 T cells while ribavirin treatment did not. The results of ELISA showed that curcumol (0.025 mg/mL and 0.0125 mg/mL) has significantly increased the expression of IFN-β protein in EMCV-infected HEK-293 T cells. The results of Western blot showed that curcumol can inhibit the degradation of TANK protein mediated by EMCV and promote the expression of MDA5 and P-IRF3, while the protein expression level of MAVS and IRF3 remain unchanged. Conclusion: Curcumol has biological activity against EMCV which we suggest that IFN-β signaling pathway is one of its mechanisms.

Background: Porcine circovirus type 2 (PCV2) is an important and common DNA virus that infect pig and can cause immunosuppression and induce apoptosis in the infected cells. To escape the host immune system, PCV2 constantly builds up complex mechanisms or mutates genes, and that is why it is difficult to eradicate complex PCV2 infection by relying on vaccines and single compound. At present, there is few literature reports on the effective prevention and treatment of PCV2 infection by a combination of two or more compounds. Previously, we have demonstrated the anti-PCV2 effect of Matrine in vitro, but its mechanism has not been further evaluated. Literatures have proven that Osthole has a variety of pharmacological activities, and we tested the ability of Osthole to inhibit PCV2 replication in cell culture. Therefore, this study explored the synergistic antiviral effect of Matrine combined with Osthole and their synergistic anti-apoptotic mechanism. Results: Osthole alone had an anti-PCV2 effect, and then its synergistic anti-PCV2 effect of Osthole and Matrine was better than that of Matrine or Osthole alone as demonstrated by qRT-PCR, IFA and Western blotting results. The anti-apoptotic mechanism of these two compounds by inducing the PERK pathway by PCV2 was elucidated through Annexin V-FITC/PI, JC-1 and Western blotting. Matrine and Osthole combination could inhibit the expression of Cap in Cap-transfected PK-15 cells, thus inhibiting Cap-induced PERK apoptosis. Ribavirin was used as a positive control. Conclusions: The combination of Osthole and Matrine had the synergistic effect of anti-PCV2 infection by directly inhibiting the expression of PCV2 Cap protein. The combination of these two compounds also inhibited PERK apoptosis induced by PCV2 Cap protein, possibly by regulating the level of GRP78. The results formed a base for further studies on the mechanism of anti-PCV2 in vivo using Matrine and Osthole combination and developing new anti-PCV2 compounds with Cap and GRP78 as therapeutic targets.

The aims of the present study were to investigate the effects of esculetin on the proliferation of human hepatocellular carcinoma SMMC-7721 cells and to determine the underlying mechanism behind this activity. An MTT assay was used to assess cell proliferation, reverse transcription-quantitative polymerase chain reaction was used to determine the relative mRNA expression levels of β-catenin, c-Myc and cyclin D1, and western blot analysis was utilized to determine the levels of the associated proteins. Compared with the dimethyl sulfoxide control, esculetin reduced the cell viability of SMMC-7721 and HL-7702 cells in a dose- and time-dependent manner. Treatment of SMMC-7721 cells with esculetin resulted in downregulation of the mRNA and protein levels of β-catenin, c-Myc and cyclin D1. Esculetin increased the phosphorylation of β-catenin at Ser33/Ser37/Thr41 and inhibited the proliferation of human hepatoma SMMC-7721 cells by suppressing the Wnt signaling pathway. The results of the present study suggest that esculetin inhibited the Wnt/β-catenin signaling pathway in SMMC-7721 cells and may have potential as an effective anti-cancer drug, acting to inhibit the Wnt/β-catenin signaling pathway.