ObjectiveThis study employs a special conformational engineering (CE) technology to construct an α-chymotrypsin-like active center, which includes a catalytic triad, an oxyanion hole, and a substrate-binding site, on silver nanoparticles (AgNPs), thereby creating an AgNP-based artificial hydrolase with high catalytic activity. This study provides a new approach for the design of highly efficient artificial enzymes and enzyme-mimicking. MethodsAgNPs were chosen as the scaffold to build the an α-chymotrypsin-like active center. A special CE procedure enables the designed peptide, Triad5, to adopt an α‑helical conformation on AgNPs, with the key catalytic residues located on one side of the α-helix forming a catalytic active center with a catalytic triad, an oxyanion hole, and a substrate-binding site. The CE procedure consists of three steps, including conformation induction via trifluoroethanol (TFE), conformation stabilization on AgNPs via Ag-S bonds, and TFE removal via lyophilization. Circular dichroism (CD) spectra were used to confirm the formation and stabilization of the α-helix conformation. Mutations of the key residues combined with stopped-flow kinetic experiments were used to demonstrate the indispensability of each key residue and the synergistic effects among the catalytic triad, the oxyanion hole, and the substrate-binding site. ResultsCD spectra show that the designed Triad5 alone is in random coil conformation; when conjugated on AgNPs, Triad5 still remains largely unstructured; but after the CE treatment, Triad5 adopts a typical α-helical conformation on AgNPs as designed, thus produces an AgNP-based artificial hydrolase, Silverzyme. Silverzyme exhibits extremely high hydrolytic activity towards p-nitrophenyl acetate (p-NPA), with an extremely high catalytic turnover number per active site of 3.5 s^-1, which is even higher than that of α-chymotrypsin. As a comparison, the AgNP-Triad5 conjugate without CE treatment shows much lower catalytic activity than Silverzyme, highlighting the important role of the right conformation of the active center for the catalytic activity and the power of the CE treatment. When the key residues of the catalytic triad of Silverzyme were mutated to alanine, the overall catalytic efficiency of this mutant dropped by about 2 orders of magnitude, unambiguously demonstrating the key role of the designed catalytic triad. Similarly, when the residues for the oxyanion hole were deleted, the mutant with the intact catalytic triad also showed significantly decreased catalytic activity, highlighting the indispensable role of the oxyanion hole for the catalytic activity. Unexpectedly, when both the catalytic triad and the oxyanion hole were kept intact, a slight change of the binding site also resulted in significantly decreased catalytic activity, indicating that the designed binding site is at the right position to align the substrate in the right orientation in the active center for catalytic hydrolysis. These results confirm the synergy among the catalytic triad, the oxyanion hole, and the substrate-binding site, indicating successful mimicking of the active center of α-chymotrypsin. Moreover, Silverzyme shows better thermal stability than α-chymotrypsin, and can even hydrolyze the tough non-activated ester diethyl phthalate, a priority pollutant by the United States Environmental Protection Agency (USEPA). ConclusionThis study successfully mimicked the complex catalytic active center of α-chymotrypsin using a conformational engineering strategy, and produced a highly active artificial hydrolase with a well-defined structure and catalytic mechanism. The findings highlight the significant potential of conformational engineering.

Background and aims The mechanism of cholestatic liver injury (CLI) is unclear, and effective therapies are lacking. While peroxisome proliferator-activated receptor alpha (PPARα) agonists show potential hepatoprotective effect and pyroptosis is implicated in hepatocellular damage, how PPARα activation mitigates lithocholic acid (LCA)-induced pyroptosis remains unknown. Methods The hepatoprotective effect of PPARα agonists was evaluated in a mouse model of intrahepatic cholestasis induced by LCA. Liver injury was assessed via serum biochemistry, hematoxylin and eosin and TUNEL staining, and electron microscopy. Pyroptosis pathways were analyzed using real-time quantitative polymerase chain reaction, Western blot, and co-immunoprecipitation. Results Combined morphological, histopathological, and biochemical analyses confirmed that PPARα activation protects against CLI. Compared with LCA treatment alone, PPARα activation significantly attenuated the elevation of serum lactate dehydrogenase (LDH), the increased TUNEL-positive cells, and the formation of hepatocyte membrane pores. Mechanistically, PPARα activation suppressed both NOD-like receptor protein 3 (NLRP3) inflammasome-mediated pyroptosis and apoptosis protease-activating factor-1 (APAF-1)/CASPASE-3/GSDME-mediated pyroptosis. Furthermore, PPARα agonist pretreatment inhibited activation of the nuclear factor-kappa B (NF-κB) and forkhead box O1 (FOXO1) signaling pathways. Conclusions PPARα protects against LCA-induced CLI by inhibiting both NLRP3 inflammasome-mediated pyroptosis associated with NF-κB and APAF-1/CASPASE-3/GSDME-mediated pyroptosis associated with the FOXO1 signaling pathway.

Aim To explore the protective effect of icariin on the damage of tight junctional function of Sertoli cells in naturally aging mice and the related mechanism.Methods 15-month-old C57BL/6J male mice were randomly divided into three groups:aging model group,low-dose and high-dose icariin treatment group(5 and 20 mg·kg-1).Another 1-month-old C57BL/6J male mice were considered as adult control group(n=10).The mice in adult control group and aging model group were given the vehicle(0.5％sodi-um carboxymethyl cellulose solution)by intragastric administration,while the mice in icariin-treated groups were given different concentrations of icariin,respec-tively.After continuous administration of icariin for three months,the testes and epididymis were immedi-ately removed,weighed,and the organ index was calcu-lated.Sperm viability and sperm concentration in epi-didymis were measured.The morphological changes of testes were observed by HE staining.The ultrastructur-al changes of tight junctions of Sertoli cells were ob-served by transmission electron microscopy.The ex-pression levels of tight junction-related proteins ZO-1,Occludin,and Claudin11 of testicular Sertoli cells were detected by Western blot.The expression and localiza-tion of ZO-1,Occludin,Raptor,Rictor,p-70S6K,and p-rps6 were detected by immunofluorescence.Results Compared with the aging model group,icariin signifi-cantly increased testicular weight and its index,and ep-ididymal index,improved sperm viability and increased sperm concentration in naturally aging mice.In addi-tion,icariin improved the degeneration of testicular morphology and the damage of ultrastructure of Sertoli cell tight junction with aging.Furthermore,Western blot results showed that icariin up-regulated the expres-sion of ZO-1 and Occludin,but had no significant effect on the expression of Claudin 11.Immunofluorescence assay showed that icariin up-regulated the expression of Rictor,and down-regulated the expression of p-70S6K,p-rps6 and Raptor.Conclusions Icariin improves the tight junction damage of Sertoli cells in naturally aging mice,and its mechanism may be related to restoring the balance between mTORC1 and mTORC2.

Objective To construct an animal model of dilated cardiomyopathy(DCM)with heart failure toxin syndrome that conforms to the characteristics of traditional Chinese medicine(TCM)syndrome and identify potential biomarkers or intervention targets for DCM with heart failure toxin syndrome.Methods Fifteen male SD rats were divided into a blank control,doxorubicin,or DCM with heart failure toxin syndrome group using a random number table method,with five rats per group.The doxorubicin group received intraperitoneal injection of doxorubicin at a dose of 1.25 mg/kg,administered on the first and fourth days of each week,along with a standard diet.The DCM with heart failure toxin syndrome group,in addition to the doxorubicin treatment,was given 42％white liquor(10 mL/kg)via gavage every other day,along with a 45％high-fat feed and 10％fructose water.The blank control group received intraperitoneal injection of an equivalent volume of phosphate-buffered saline at the same time points as the doxorubicin group,along with a standard diet.The model was established for 10 weeks.At the fourth and tenth weeks of modeling,echocardiography was performed to measure left ventricular ejection fraction(LVEF),fractional shortening(FS),systolic left ventricular posterior wall thickness(LVPWs),diastolic left ventricular posterior wall thickness,systolic left ventricular internal diameter(LVIDs),and diastolic left ventricular internal diameter(LVIDd);macroscopic changes in fur color of the rats were assessed using the red-green-blue colorimetric method.After modeling,the open field test was conducted to evaluate the exercise tolerance of the rats,and the grip strength test was performed to assess changes in forelimb grip strength.Hematoxylin-eosin,Masson,and wheat germ agglutinin staining were used to evaluate pathological changes in cardiac tissue.Bulk RNA sequencing analysis was performed to identify differentially expressed genes(DEGs)in the hearts of rats between the blank control and the DCM with heart failure toxin syndrome groups.Using DCM,the Blue value of rat fur color,and forelimb grip strength as phenotypic traits,weighted gene co-expression network analysis(WGCNA)was performed to screen for characteristic module gene sets(MEs)associated with DCM with heart failure toxin syndrome.Overlapping analysis was performed on DEGs,immune-related gene sets,and MEs,and the intersecting genes were identified as potential biomarkers or intervention targets for DCM with heart failure toxin syndrome.The sensitivity and specificity of these targets were evaluated using receiver operating characteristic(ROC)curve analysis.Results Compared with the blank control group,at the tenth week of modeling,the LVEF,FS,and LVPWs of rats in the doxorubicin group and the DCM with heart failure toxin syndrome group decreased,whereas LVIDs and LVIDd increased,and the movement distance of the open field test and forelimb grip strength were reduced(P＜0.05).At the 10th week of modeling,the Blue value of fur color in the DCM with heart failure toxin syndrome group was significantly lower than that of the blank control and doxorubicin groups(P＜0.05).Compared with the blank control group,rats in the doxorubicin and DCM with heart failure toxin syndrome groups exhibited significant cardiac dilation and increased immune cell infiltration in cardiac tissue,accompanied by collagen deposition and cardiomyocyte hypertrophy.Bulk RNA sequencing identified 2,003 DEGs,including 1,082 downregulated genes and 921 upregulated genes.WGCNA results revealed that the MEturquoise module had the strongest positive correlation with DCM and the strongest negative correlation with the Blue value and forelimb grip strength.The overlapping analysis identified four intersecting genes:bone morphogenetic protein 6(Bmp6),serine-threonine-protein kinase 1(Pak1),proto-oncogene JunD(JunD),and S100 calcium-binding protein A3(S100A3).ROC curve analysis demonstrated that these four genes exhibited high sensitivity and specificity for DCM with heart failure toxin syndrome.Conclusion The rat model constructed by intraperitoneal injection of doxorubicin combined with a high-fat feed,fructose water,and white liquor gavage closely aligns with the characteristics of the DCM with heart failure toxin syndrome.Bmp6,JunD,Pak1,and S100A3 are potential biomarkers or therapeutic targets for DCM heart failure toxin syndrome.

Aim To explore the protective effect of icariin on the damage of tight junctional function of Sertoli cells in naturally aging mice and the related mechanism.Methods 15-month-old C57BL/6J male mice were randomly divided into three groups:aging model group,low-dose and high-dose icariin treatment group(5 and 20 mg·kg-1).Another 1-month-old C57BL/6J male mice were considered as adult control group(n=10).The mice in adult control group and aging model group were given the vehicle(0.5％sodi-um carboxymethyl cellulose solution)by intragastric administration,while the mice in icariin-treated groups were given different concentrations of icariin,respec-tively.After continuous administration of icariin for three months,the testes and epididymis were immedi-ately removed,weighed,and the organ index was calcu-lated.Sperm viability and sperm concentration in epi-didymis were measured.The morphological changes of testes were observed by HE staining.The ultrastructur-al changes of tight junctions of Sertoli cells were ob-served by transmission electron microscopy.The ex-pression levels of tight junction-related proteins ZO-1,Occludin,and Claudin11 of testicular Sertoli cells were detected by Western blot.The expression and localiza-tion of ZO-1,Occludin,Raptor,Rictor,p-70S6K,and p-rps6 were detected by immunofluorescence.Results Compared with the aging model group,icariin signifi-cantly increased testicular weight and its index,and ep-ididymal index,improved sperm viability and increased sperm concentration in naturally aging mice.In addi-tion,icariin improved the degeneration of testicular morphology and the damage of ultrastructure of Sertoli cell tight junction with aging.Furthermore,Western blot results showed that icariin up-regulated the expres-sion of ZO-1 and Occludin,but had no significant effect on the expression of Claudin 11.Immunofluorescence assay showed that icariin up-regulated the expression of Rictor,and down-regulated the expression of p-70S6K,p-rps6 and Raptor.Conclusions Icariin improves the tight junction damage of Sertoli cells in naturally aging mice,and its mechanism may be related to restoring the balance between mTORC1 and mTORC2.

Objective To construct an animal model of dilated cardiomyopathy(DCM)with heart failure toxin syndrome that conforms to the characteristics of traditional Chinese medicine(TCM)syndrome and identify potential biomarkers or intervention targets for DCM with heart failure toxin syndrome.Methods Fifteen male SD rats were divided into a blank control,doxorubicin,or DCM with heart failure toxin syndrome group using a random number table method,with five rats per group.The doxorubicin group received intraperitoneal injection of doxorubicin at a dose of 1.25 mg/kg,administered on the first and fourth days of each week,along with a standard diet.The DCM with heart failure toxin syndrome group,in addition to the doxorubicin treatment,was given 42％white liquor(10 mL/kg)via gavage every other day,along with a 45％high-fat feed and 10％fructose water.The blank control group received intraperitoneal injection of an equivalent volume of phosphate-buffered saline at the same time points as the doxorubicin group,along with a standard diet.The model was established for 10 weeks.At the fourth and tenth weeks of modeling,echocardiography was performed to measure left ventricular ejection fraction(LVEF),fractional shortening(FS),systolic left ventricular posterior wall thickness(LVPWs),diastolic left ventricular posterior wall thickness,systolic left ventricular internal diameter(LVIDs),and diastolic left ventricular internal diameter(LVIDd);macroscopic changes in fur color of the rats were assessed using the red-green-blue colorimetric method.After modeling,the open field test was conducted to evaluate the exercise tolerance of the rats,and the grip strength test was performed to assess changes in forelimb grip strength.Hematoxylin-eosin,Masson,and wheat germ agglutinin staining were used to evaluate pathological changes in cardiac tissue.Bulk RNA sequencing analysis was performed to identify differentially expressed genes(DEGs)in the hearts of rats between the blank control and the DCM with heart failure toxin syndrome groups.Using DCM,the Blue value of rat fur color,and forelimb grip strength as phenotypic traits,weighted gene co-expression network analysis(WGCNA)was performed to screen for characteristic module gene sets(MEs)associated with DCM with heart failure toxin syndrome.Overlapping analysis was performed on DEGs,immune-related gene sets,and MEs,and the intersecting genes were identified as potential biomarkers or intervention targets for DCM with heart failure toxin syndrome.The sensitivity and specificity of these targets were evaluated using receiver operating characteristic(ROC)curve analysis.Results Compared with the blank control group,at the tenth week of modeling,the LVEF,FS,and LVPWs of rats in the doxorubicin group and the DCM with heart failure toxin syndrome group decreased,whereas LVIDs and LVIDd increased,and the movement distance of the open field test and forelimb grip strength were reduced(P＜0.05).At the 10th week of modeling,the Blue value of fur color in the DCM with heart failure toxin syndrome group was significantly lower than that of the blank control and doxorubicin groups(P＜0.05).Compared with the blank control group,rats in the doxorubicin and DCM with heart failure toxin syndrome groups exhibited significant cardiac dilation and increased immune cell infiltration in cardiac tissue,accompanied by collagen deposition and cardiomyocyte hypertrophy.Bulk RNA sequencing identified 2,003 DEGs,including 1,082 downregulated genes and 921 upregulated genes.WGCNA results revealed that the MEturquoise module had the strongest positive correlation with DCM and the strongest negative correlation with the Blue value and forelimb grip strength.The overlapping analysis identified four intersecting genes:bone morphogenetic protein 6(Bmp6),serine-threonine-protein kinase 1(Pak1),proto-oncogene JunD(JunD),and S100 calcium-binding protein A3(S100A3).ROC curve analysis demonstrated that these four genes exhibited high sensitivity and specificity for DCM with heart failure toxin syndrome.Conclusion The rat model constructed by intraperitoneal injection of doxorubicin combined with a high-fat feed,fructose water,and white liquor gavage closely aligns with the characteristics of the DCM with heart failure toxin syndrome.Bmp6,JunD,Pak1,and S100A3 are potential biomarkers or therapeutic targets for DCM heart failure toxin syndrome.

Aim To investigate the effect of Shenqi Dihuang decoction(SQDH)on henoch-schonlein pur-pura nephritis(HSPN)rats by regulating AMPK/Sirt1/Nrf2 mediated ferroptosis and the possible mech-anism.Methods Thirty SD rats were randomly divid-ed into a control group(Control),HSPN group,SQDH low-dose group(SQDH-L,5.4 g·kg-1),SQDH high-dose group(SQDH-H,21.6 g·kg-1),and SQDH high-dose+AMPK inhibitor group(SQDH-H+CC,20 mg·kg-1),with six rats in each group.Except for the control group,all other groups of rats were injected intraperitoneally with ovalbumin and complete Freund's adjuvant to establish HSPN rat models.After the successful construction of the model,each group of rats was orally administered with the cor-responding dosage or physiological saline once a day for five weeks.HE staining was used to observe the his-topathological changes in renal tissues;immunohisto-chemistry(IHC)was employed to detect the deposition of IgA and IgG in renal tissues;serum biochemical pa-rameters of renal function and urinary protein levels were measured;commercial assay kits were utilized to determine oxidative stress markers and Fe2+levels in renal tissues;Western blot analysis was performed to assess ferroptosis-related proteins and the protein ex-pression of the AMPK/Sirt1/Nrf2 signaling pathway in renal tissues.Results Compared with the control group,the HSPN group showed significant pathological damage in kidney tissue,with significantly increased scores,increased deposition of IgA and IgG in kidney tissue,decreased serum total protein(TP)and albu-min(ALB),and average increases in serum creatinine(Cre),urea nitrogen(BUN),and urinary protein levels(P＜0.05).The levels of MDA,ROS,Fe2+,and ACSL4 protein expression in the kidney tissue sig-nificantly increased,while SOD activity,SLC7A11,GPX4,p-AMPK/AMPK,Sirt1,and Nrf2 protein ex-pression significantly decreased(P＜0.05).Com-pared with the HSPN group,the pathological damage to renal tissue was reduced,IgA and IgG deposition in renal tissue decreased,TP and ALB decreased,Cre,BUN,and urinary protein levels were all reduced(P＜0.05),and the levels of MDA,ROS,Fe2+,and ACSL4 protein expression in renal tissue were signifi-cantly reduced in each dose group of SQDH rats.SOD activity,SLC7A11,GPX4,p-AMPK/AMPK,Sirt1,and Nrf2 protein expression significantly increased(P＜0.05).Compared with the SQDH-H group,the AMPK inhibitor CC could inhibit the AMPK/Sirt1/Nrf2 signaling pathway induced ferroptosis and reverse the protective effect of SQDH on renal injury in HSPN rats.Conclusions SQDH can improve renal injury in HSPN rats,and its mechanism may be related to the activation of AMPK/Sirt1/Nrf2 signaling pathway to in-hibit ferroptosis.

Objective:To explore the therapeutic effect of Bupiqiangli compound on experimental myasthenia gravis with sub-clinical hypothyroidism in rats and the influence of hypothalamus-pituitary-thyroid-thymus(HPTT)axis.Methods:SPF Lewis rats were randomly divided into normal group,model group,Bupiqiangli compound low-dose,medium-dose and high-dose groups.Model rats were immunized with AchR-α subunit 97-116 peptide sequence to construct an experimental myasthenia gravis model,and then methimazole was used to prepare an experimental myasthenia gravis with subclinical hypothyroidism model.Bupiqiangli compound low-dose,medium-dose and high-dose groups were given 4.57 g/kg,7.12 g/kg and 9.49 g/kg of Bupiqiangli compound by gavage,nor-mal group and model group were given an equal volume of normal saline by gavage,once a day,for 4 weeks.After the last gavage,Lennon scores of rats in each group were recorded;HE staining was used to detect pathological changes of thymus and thyroid;ELISA was used to detect expression levels of acetylcholine receptor antibody(AchRab),thyroid stimulating hormone(TSH),thyrotropin releasing hormone(TRH),free thyroxine(FT4)and thyroxine(T4)in serum;mRNA level of TRH in hypothalamus and TSH in pituitary tissue were detected by qPCR;Western blot detected changes of protein expressions of Cleaved Caspase3,Bcl2 associated X protein(Bax)and B-cell lymphoma-2(Bcl2)in thymus.Results:Compared with normal group,model group showed obvious symp-toms of muscle weakness,Lennon score increased significantly(P<0.05),obvious pathological changes in thymus and thyroid tissues,while no significant changes in expressions of FT4 and T4 in serum(P>0.05),expressions of AchRab,TSH and TRH in serum were significantly increased(P<0.05),expressions of TRH in hypothalamus and TSH in pituitary were significantly increased(P<0.05),protein expressions of Cleaved Caspase3 and Bax in thymus were significantly decreased(P<0.05),while expression of Bcl2 protein in thymus increased significantly(P<0.05).Compared with model group,myasthenia symptoms of compound high-dose group were im-proved,Lennon score was significantly decreased(P<0.05),pathological changes of thymus and thyroid tissues were improved,ex-pressions of FT4 and T4 in serum had no significant changes(P>0.05),expressions of AchRab,TSH and TRH in serum were signifi-cantly decreased(P<0.05),expressions of TRH in hypothalamus and TSH in pituitary were significantly decreased(P<0.05),expres-sions of Cleaved Caspase3 and Bax in thymus were significantly increased(P<0.05),while expression of Bcl2 in thymus was signifi-cantly decreased(P<0.05).Conclusion:Bupiqiang compound can improve clinical symptoms of experimental myasthenia gravis with subclinical hypothyroidism in rats,and its mechanism may be related to the regulation of HPTT axis.

Objective:To analyze the independent risk factors for colorectal serrated adenomas to develop heterogeneous hyperplasia or carcinoma,to construct a clinical prediction model and to evaluate and validate it.Methods:The clinical data characteristics of 737 patients with colorectal serrated adenomas who underwent electronic colonoscopy in the Gastrointestinal Endoscopy Unit of the Fourth Affiliated Hospital of Harbin Medical University were retrospectively analyzed,and they were randomly divided into the training set and the validation set with 515 and 222 cases,respectively,using R software(7∶3),and were classified into the group with no neoplasia according to their histological characteristics The independent risk factors were screened by univariate and multivariate logistic regression analyses and included in the R software,and the predictive model was evaluated using the"RMS"package with column-line plots,using the subjects'work characteristic curves,calibration curves,and decision curves,and then validated using the data from the validation set.Results:1.The incidence of heterogeneous hyperplasia and carcinoma in colorectal serrated adenomas in this study was 31.1％and 1.1％,respectively,and multifactorial logistic regression analysis showed that Age,diameter,and morphology were independent risk factors for the occurrence of heterogeneous hyperplasia or carcinoma in colorectal SA;2.The three independent risk factors of age,diameter,and morphology were applied to establish a column-line diagram,and the model was verified as having clinical predictive value for the occurrence of heterogeneous hyperplasia and carcinoma in serrated adenomas.Conclusions:In this study,age,diameter,and morphology were concluded to be the independent risk factors for the development of heterogeneous hyperplasia and carcinoma in colorectal serrated adenomas,and the column chart constructed on the basis of these factors had clinical predictive value.

Objective:To explore the role and mechanism of intestinal endotoxemia in the development of hepatopulmonary syndrome in rats.Methods:Rats were randomly divided into Experimental Group(N=10)and Control Group(N=10),and the rat model of Hepatopulmonary Syndrome was established by common bile duct ligation(CBD),and the contents of endotoxin,TNF-α and IL-6 were measured.Rat lung microvascular endothelial cells were isolated and cultured in vitro.Endotoxin induced the activation and proliferation of these cells,and the levels of TNF-α and IL-6 were detected.Results:The level of endotoxin in rats with hepatopulmonary syndrome was significantly elevated,which induced the production of TNF-α and IL-6,causing pulmonary vasodilation and hypoxemia.Conclusions:Intestinal endotoxemia plays an important role in the development of Hepatopulmonary Syndrome,and its possible mechanism is to induce pulmonary microvascular endothelial cells to produce a variety of inflammatory cytokines and to promote the development of pulmonary vasodilation and Hepatopulmonary Syndrome.It provides key experimental evidence and potential targets for the prevention and treatment strategies of hepatopulmonary syndrome.