The Regulatory Effect Of Platycodon Grandiflorus Polysaccharide On Inflammation Caused By PCV2 Infection

Porcine circovirus type 2(PCV2)has become a pathogen that cannot be ignored in pig farms due to its high detection rate and high infectivity,and PCV2 can cause PCV2-related pneumonia and enteritis in addition to causing multisystem failure syndrome in weaned piglets.Under the existing conditions and breeding modes of pig farms,after the pigs suffer from swine circovirus disease(PCVAD),they are mostly manifested as immunosuppression,retarded growth,multi-system inflammation,which bring serious economic losses to the pig farm.Therefore,it is necessary and urgent to study drugs related to the alleviation of excessive inflammatory responses caused by PCV2.Chinese veterinary drugs are safe and efficient,and they have outstanding advantages in"prevention before illness,prevention of disease".Polysaccharides are the main active substances in traditional Chinese medicine,with significant immunomodulatory,anti-inflammatory,anti-apoptosis,antioxidant and other effects,and are the material basis for"strengthening healthy energy"and enhancing immune function.Previous studies have found that Platycodon grandiflorus polysaccharide(PGPS_t)have enhanced non-specific immunity and cellular immunity,which can improve the body's disease resistance.However,the effect of PGPS_ton the excessive inflammatory response caused by PCV2 infection is currently unclear.Therefore,this study is dedicated to the study of anti-inflammatory drugs that can alleviate the inflammatory response caused by PCV2infection.To study the in vivo and in vitro anti-inflammatory effect of PGPS_t,inflammatory response model established by PCV2 infection with 3D4/21 cells and mice,3D4/21 cells and Kunming mice are selected as research objects.To clarify the effect of PGPS_ton cell activity,treating 3D4/21 cells and PCV2-infected3D4/21 cells with different concentrations of PGPS_tfor 36 h found that PGPS_twas non-toxic to 3D4/21 cells and protected infected cells from inflammatory damage.In order to further explore the regulatory effect of PGPS_ton the inflammatory response caused by PCV2infection with 3D4/21 cells,ELISA and q PCR detected the levels of inflammatory factors of IL-1?,IL-6,IL-10 and TNF-?,Western Blot detected histone H3 and histone H4 acetylation levels and i NOS and COX-2 protein expression,and further detected the effect of PGPS_ton the NF-?B and MAPKs signaling pathways.The results showed that compared with the PCV2group,200?g/m L PGPS_twas able to significantly inhibit the high acetylatation of histone H3and histone H4,downregulate the activity of histone acetyltransferase(HAT)and upregulate histone deacetylase(HDAC),inhibit the expression of i NOS and COX-2 protein levels,reduce the levels of pro-inflammatory factors of IL-1?,IL-6 and TNF-?,increase the levels of anti-inflammatory factors IL-10,inhibit p65,p38 and Erk1/2 phosphorylation levels.The results showed that 200?g/m L PGPS_tcould exert the anti-inflammatory effect of PGPS_tin vitro by inhibiting the expression of inflammatory factors and pro-inflammatory enzymes,and inhibiting the activation of NF-?B and MAPKs signaling pathways.In order to further study the anti-inflammatory protective effect of PGPS_t,a model of the inflammatory response caused by PCV2 infection in mice was constructed.The experiment set up the control group,the PCV2 infection group,and the PGPS_tintervention group.The serum inflammation factor level in mice was detected by the ELISA method,and Western Blot detected the expression of pro-inflammatory proteins in spleen tissues.The results showed that PGPS_tsignificantly inhibited the secretion of IL-6,IL-1?and TNF-?,promoted the expression of IL-10,and inhibited the expression of PCV2-induced i NOS and COX-2.The results showed that PGPS_tplayed a significant anti-inflammatory role in the model of the inflammatory response caused by PCV2 infection in mice.In summary,PGPS_thas an anti-inflammatory effect on the in vivo and in vitro inflammatory response caused by PCV2 infection,which provides a basic reference basis for in-depth study of the anti-inflammatory mechanism of PGPS_t,and provides theoretical data support for the research,development and application of active ingredients of traditional Chinese medicine.