Aim To establish the pyroptosis model of rat chondrocytes induced by tumor necrosis factor α(TNF-α)in order to study the effect of lysine acetyl-transferase 7(KAT7)on pyroptosis of chondrocytes.Methods Chondrocytes of rat knee joint were isolated by type Ⅱ collagenase digestion,and were identified by toluidine blue staining and Col Ⅱ immunofluorescence.CCK-8 was used to evaluate cell viability.Western blot was used to detect the expression of pyroptosis-related proteins NLRP3,GSDMD,caspase-8 and KAT7 in cells intervened with TNF-α,adenovirus overexpression of KAT7(KAT7-oe)and KAT7 inhibitor WM-3835.The microstructure of the cells was observed by scanning e-lectron microscopy.Pyroptosis was detected by TUNEL staining,and the expression of pyroptosis-related pro-tein and KAT7 was detected by immunofluorescence.Results Compared with the empty virus group,KAT7-oe inhibited cell viability,promoted the expression of pyroptosis-related proteins,and TNF-α enhanced this effect.At the same time,the expression of KAT7 and pyroptosis-related proteins in the TNF-α stimulation group increased,and WM-3835 reduced the related proteins expression.Electron microscopy showed that KAT7-oe caused cell swelling,deformation,membrane perforation and rupture,while WM-3835 could restore cell morphology.TUNEL staining and immunofluores-cence results also confirmed that KAT7-oe induced chondrocyte pyroptosis,and WM-3835 could down-reg-ulate the fluorescence of pyroptosis-related proteins.Conclusions The expression of KAT7 increases in rat chondrocyte pyroptosis model,and the intervention of KAT7 expression affects signal molecules related to py-roptosis pathway,suggesting that KAT7 may be related to chondrocyte pyroptosis.

Aim To explore the effect of astragalosideⅣ(AS-Ⅳ)on lipopolysaccharide(LPS)-induced po-larization and migration of RAW 264.7 macrophages and the underlying mechanism.Methods 1 mg·L-1 LPS was used to construct cell migration model.Scratch assay was utilized to determine cell migration rate.Immunofluorescence staining was utilized to de-tect the expression and location of F4/80,iNOS and Arg-1.CCK-8 assay was used to determine the viabili-ty of RAW 264.7 cells.Griess assay was used to measure NO content.Molecular docking was used to analyze the interaction between AS-Ⅳ and the core tar-gets such as cGAS and STING protein.Western blot was employed to detect the expression of iNOS,Arg-1,cGAS,STING,NF-κB p65 and p-NF-κB p65 protein.Results AS-Ⅳ significantly inhibited the migration and M1 polarization of RAW 264.7 cells induced by LPS.Moreover,AS-Ⅳ could interact with cGAS and STING protein,especially cGAS.Further Western blot assay showed that AS-Ⅳ significantly downregulated the expression of iNOS,cGAS,STING and p-NF-κB p65 protein.Conclusions AS-Ⅳ could promote mac-rophage M1 to M2 polarization,thereby inhibited mac-rophage migration through restraining the cGAS/STING/NF-κB signaling pathway,which provides a new therapeutic target for AS-Ⅳ to improve the early inflammatory response of AS.

Aim To establish the pyroptosis model of rat chondrocytes induced by tumor necrosis factor α(TNF-α)in order to study the effect of lysine acetyl-transferase 7(KAT7)on pyroptosis of chondrocytes.Methods Chondrocytes of rat knee joint were isolated by type Ⅱ collagenase digestion,and were identified by toluidine blue staining and Col Ⅱ immunofluorescence.CCK-8 was used to evaluate cell viability.Western blot was used to detect the expression of pyroptosis-related proteins NLRP3,GSDMD,caspase-8 and KAT7 in cells intervened with TNF-α,adenovirus overexpression of KAT7(KAT7-oe)and KAT7 inhibitor WM-3835.The microstructure of the cells was observed by scanning e-lectron microscopy.Pyroptosis was detected by TUNEL staining,and the expression of pyroptosis-related pro-tein and KAT7 was detected by immunofluorescence.Results Compared with the empty virus group,KAT7-oe inhibited cell viability,promoted the expression of pyroptosis-related proteins,and TNF-α enhanced this effect.At the same time,the expression of KAT7 and pyroptosis-related proteins in the TNF-α stimulation group increased,and WM-3835 reduced the related proteins expression.Electron microscopy showed that KAT7-oe caused cell swelling,deformation,membrane perforation and rupture,while WM-3835 could restore cell morphology.TUNEL staining and immunofluores-cence results also confirmed that KAT7-oe induced chondrocyte pyroptosis,and WM-3835 could down-reg-ulate the fluorescence of pyroptosis-related proteins.Conclusions The expression of KAT7 increases in rat chondrocyte pyroptosis model,and the intervention of KAT7 expression affects signal molecules related to py-roptosis pathway,suggesting that KAT7 may be related to chondrocyte pyroptosis.

Aim To explore the effect of astragalosideⅣ(AS-Ⅳ)on lipopolysaccharide(LPS)-induced po-larization and migration of RAW 264.7 macrophages and the underlying mechanism.Methods 1 mg·L-1 LPS was used to construct cell migration model.Scratch assay was utilized to determine cell migration rate.Immunofluorescence staining was utilized to de-tect the expression and location of F4/80,iNOS and Arg-1.CCK-8 assay was used to determine the viabili-ty of RAW 264.7 cells.Griess assay was used to measure NO content.Molecular docking was used to analyze the interaction between AS-Ⅳ and the core tar-gets such as cGAS and STING protein.Western blot was employed to detect the expression of iNOS,Arg-1,cGAS,STING,NF-κB p65 and p-NF-κB p65 protein.Results AS-Ⅳ significantly inhibited the migration and M1 polarization of RAW 264.7 cells induced by LPS.Moreover,AS-Ⅳ could interact with cGAS and STING protein,especially cGAS.Further Western blot assay showed that AS-Ⅳ significantly downregulated the expression of iNOS,cGAS,STING and p-NF-κB p65 protein.Conclusions AS-Ⅳ could promote mac-rophage M1 to M2 polarization,thereby inhibited mac-rophage migration through restraining the cGAS/STING/NF-κB signaling pathway,which provides a new therapeutic target for AS-Ⅳ to improve the early inflammatory response of AS.

Aim To investigate the effect of PU.1 in-hibitor DB2313 on lupus nephritis in MRL/lpr mice and its mechanism.Methods Thirty female MRL/lpr mice were randomly divided into the model group,DB2313 group and TACI-Ig group,with 10 mice in each group.Another 10 female BALB/c mice were se-lected as normal control groups.Mice in the DB2313 group received intraperitoneal DB2313 injections every two days,and those in the TACI-Ig group received subcutaneous injections of TACI-Ig every two days.Mice in the control group and model group were intra-gastrically given the same amount of 0.9％NaCl injec-tion every day.Before the drug intervention and for 1 to 5 weeks after the intervention,the urine of mice was collected regularly,the urine protein content was meas-ured,and the renal damage index was evaluated.The histopathological changes of kidney were observed by HE,Masson and PAS staining.The expression levels of immune complex of C3 in kidney tissue were detec-ted by immunohistochemistry.The concentrations of u-rea nitrogen(BUN),serum creatinine(Scr),inter-leukin-6(IL-6),and tumor necrosis factor alpha(TNF-α)in the serum samples were assayed utilizing the respective kits.The expression levels of PU.1 and FLT3 in kidney tissues were determined by immunoflu-orescence technology,and the protein expressions of PU.1,FLT3,PI3K,AKT and phosphorylated AKT(p-AKT)in kidney tissues were detected by Western blot.Results DB2313 treatment significantly allevia-ted the pathological damage of kidney in MRL/lpr mice,and reduced the deposition of C3,kidney injury index and 24-hour urine protein in renal tissue.The results of ELISA showed that DB2313 administration could significantly reduce the serum levels of BUN,Scr,IL-6 and TNF-α in MRL/lpr mice.The results of immunofluorescence and Western blot further showed that DB2313 treatment could significantly down-regu-late the protein expression of PU.1,PI3K and p-AKT,and up-regulate the protein expression of FLT3.Con-clusion DB2313 has an ameliorating effect on lupus nephritis in MRL/lpr mice,and its underlying mecha-nism may involve the inhibition of the transcription fac-tor PU.1-mediated signaling pathway.

Metformin has been demonstrated to attenuate hyperglycaemia by modulating the gut microbiota. However, the mechanisms through which the microbiome mediates metformin monotherapy failure (MMF) are unclear. Herein, in a prospective clinical cohort study of newly diagnosed type 2 diabetes mellitus (T2DM) patients treated with metformin monotherapy, metagenomic sequencing of faecal samples revealed that Phocaeicola vulgatus abundance was approximately 12 times higher in nonresponders than in responders. P. vulgatus rapidly hydrolysed taurine-conjugated bile acids, leading to ceramide accumulation and reversing the improvements in glucose intolerance conferred by metformin in high-fat diet-fed mice. Interestingly, C22:0 ceramide bound to mitochondrial fission factor to induce mitochondrial fragmentation and impair hepatic oxidative phosphorylation in P. vulgatus-colonized hyperglycaemic mice, which could be exacerbated by metformin. This work suggests that metformin may be unsuitable for P. vulgatus-rich T2DM patients and that clinicians should be aware of metformin toxicity to mitochondria. Suppressing P. vulgatus growth with cefaclor or improving mitochondrial function using adenosylcobalamin may represent simple, safe, effective therapeutic strategies for addressing MMF.

Aim To investigate the effect of PU.1 in-hibitor DB2313 on lupus nephritis in MRL/lpr mice and its mechanism.Methods Thirty female MRL/lpr mice were randomly divided into the model group,DB2313 group and TACI-Ig group,with 10 mice in each group.Another 10 female BALB/c mice were se-lected as normal control groups.Mice in the DB2313 group received intraperitoneal DB2313 injections every two days,and those in the TACI-Ig group received subcutaneous injections of TACI-Ig every two days.Mice in the control group and model group were intra-gastrically given the same amount of 0.9％NaCl injec-tion every day.Before the drug intervention and for 1 to 5 weeks after the intervention,the urine of mice was collected regularly,the urine protein content was meas-ured,and the renal damage index was evaluated.The histopathological changes of kidney were observed by HE,Masson and PAS staining.The expression levels of immune complex of C3 in kidney tissue were detec-ted by immunohistochemistry.The concentrations of u-rea nitrogen(BUN),serum creatinine(Scr),inter-leukin-6(IL-6),and tumor necrosis factor alpha(TNF-α)in the serum samples were assayed utilizing the respective kits.The expression levels of PU.1 and FLT3 in kidney tissues were determined by immunoflu-orescence technology,and the protein expressions of PU.1,FLT3,PI3K,AKT and phosphorylated AKT(p-AKT)in kidney tissues were detected by Western blot.Results DB2313 treatment significantly allevia-ted the pathological damage of kidney in MRL/lpr mice,and reduced the deposition of C3,kidney injury index and 24-hour urine protein in renal tissue.The results of ELISA showed that DB2313 administration could significantly reduce the serum levels of BUN,Scr,IL-6 and TNF-α in MRL/lpr mice.The results of immunofluorescence and Western blot further showed that DB2313 treatment could significantly down-regu-late the protein expression of PU.1,PI3K and p-AKT,and up-regulate the protein expression of FLT3.Con-clusion DB2313 has an ameliorating effect on lupus nephritis in MRL/lpr mice,and its underlying mecha-nism may involve the inhibition of the transcription fac-tor PU.1-mediated signaling pathway.

This study was aimed at identifying the pathogenic bacteria responsible for the death of a young tiger at the Fujian Meihua Mountain South China Tiger Breeding Research Institute.Tissue samples from the lungs,liver,and intestines of the deceased tiger were collected,and the bacteria were cultured inasterile environment.The bacterial strains were characterized according to their morphological and molecular biological properties,including assessment of virulence genes and antibiotic resistance genes,mouse lethality tests,and antibiotic susceptibility evaluations.A predominant bacterial strain isolated from the liver of the deceased tiger was identified as enterotoxigenic Escherichia coli(ETEC)strain Tiger22513F.Phylogenetic analysis of the 16S rRNA gene revealed that the Tiger22513F strain exhibited close genetic similarity to the reference strain ETEC(MF919609.1),with 99.9%nucleotide similarity,and resided on the same evolutionary branch.The Tiger22513F strain contained 11 antibiotic resistance genes(tetA,sul1,sul3,cmlA,floR,blaTEM,blaSHV,blaCMY-2,qnrA,qnrS,and qnrD)along with five virulence genes(VT1,fyuA,tsh,iucD,and ST).Mouse lethality tests indicated significant pathogenicity toward mice,affecting primarily the lungs,liver,and intestines.Antibiotic susceptibility testing demonstrated that this strain exhibited resistance to various classes of beta-lactam antibiotics,as well as quinolones and aminoglycosides.This investigation successfully isolated a multi-drug resistant enterotoxigenic Escherichia coli strain with pronounced pathogenicity from the liver of a deceased tiger;thus providing valuable scientific insights for clinical diagnosis,as well as prevention and control measures,against ETEC infections in South China tigers.

This study was aimed at identifying the pathogenic bacteria responsible for the death of a young tiger at the Fujian Meihua Mountain South China Tiger Breeding Research Institute.Tissue samples from the lungs,liver,and intestines of the deceased tiger were collected,and the bacteria were cultured inasterile environment.The bacterial strains were characterized according to their morphological and molecular biological properties,including assessment of virulence genes and antibiotic resistance genes,mouse lethality tests,and antibiotic susceptibility evaluations.A predominant bacterial strain isolated from the liver of the deceased tiger was identified as enterotoxigenic Escherichia coli(ETEC)strain Tiger22513F.Phylogenetic analysis of the 16S rRNA gene revealed that the Tiger22513F strain exhibited close genetic similarity to the reference strain ETEC(MF919609.1),with 99.9%nucleotide similarity,and resided on the same evolutionary branch.The Tiger22513F strain contained 11 antibiotic resistance genes(tetA,sul1,sul3,cmlA,floR,blaTEM,blaSHV,blaCMY-2,qnrA,qnrS,and qnrD)along with five virulence genes(VT1,fyuA,tsh,iucD,and ST).Mouse lethality tests indicated significant pathogenicity toward mice,affecting primarily the lungs,liver,and intestines.Antibiotic susceptibility testing demonstrated that this strain exhibited resistance to various classes of beta-lactam antibiotics,as well as quinolones and aminoglycosides.This investigation successfully isolated a multi-drug resistant enterotoxigenic Escherichia coli strain with pronounced pathogenicity from the liver of a deceased tiger;thus providing valuable scientific insights for clinical diagnosis,as well as prevention and control measures,against ETEC infections in South China tigers.

Aim To investigate the protective poten-tial of paeoniflorin 6-oxy-benzenesulfonate(CP-25)in preserving knee cartilage integrity in osteoarthritis mice through inhibition of GRK2 activity.Methods The posttraumatic osteoarthritis model was established fol-lowing DMM surgery.The experiment consisted of a sham operation group,a model group,a CP-25 admin-istration group,and a paroxetine positive control group.Intragastric administration commenced after the surgery.After 12 weeks of administration,the animals were euthanized.Micro-CT imaging was used to ob-serve the knee cartilage degeneration and abnormal bone remodeling,and the joint histopathology of mice was observed by staining with ferrubens solid green.Immunohistochemistry and immunofluorescence were used to detect the expression level of related molecules in cartilage tissue.Furthermore,Western blot was em-ployed to determine GRK2 and EP4 membrane protein expression levels as well as total protein levels of GRK2 and MMP13 following CP-25 treatment.Results Compared with the sham operation group,the articular cartilage in the model group was significantly degrad-ed,with the cartilage surface calcifying and osteo-phytes forming.CP-25 could significantly reduce the number of osteophytes and the thickness of the sub-chondral plate of articular cartilage,promote the regen-eration of the cartilage matrix,reduce the expression of cartilage matrix degradation protein,and have a signifi-cant protective effect on knee cartilage.Immunohisto-chemical and immunofluorescence results showed that compared with the model group,CP-25 treatment sig-nificantly decreased the expressions of GRK2,AD-AMTS5 and MMP13 in knee tissue and increased the expressions of Col Ⅱ and Aggrecan in knee tissue.The results of in vitro experiments showed that CP-25 ad-ministration could significantly reduce the expression levels of GRK2 membrane protein and total protein,in-crease the level of EP4 membrane protein,and de-crease the level of MMP13.Conclusions The ad-ministration of CP-25 can significantly promote the re-generation of articular cartilage matrix in OA mice,re-duce the degradation of cartilage matrix,and exhibit therapeutic effects on OA.The mechanism behind this is related to the inhibition of GRK2-mediated cartilage matrix metabolism.