Objective:To explore the differences between the Phoenix sepsis scoring system including Phoenix sepsis score (PSS) and Phoenix-8 organ dysfunction score (hereinafter referred to as Phoenix-8) and the commonly used pediatric sepsis scores in evaluating clinical characteristics and prognostic analysis of pediatric patients with severe sepsis diagnosed under traditional standards, namely the diagnostic criteria from the 2005 International Pediatric Sepsis Consensus Conference.Methods:This study was a retrospective observational study. From December 2020 to March 2023, 202 pediatric patients with severe sepsis meeting the inclusion criteria were admitted to the Children's Hospital of Nanjing Medical University. Based on the sepsis diagnostic criteria outlined in the International Consensus Criteria for Pediatric Sepsis and Septic Shock (2024), the pediatric patients were categorized into a sepsis group and a non-sepsis group. Sepsis group was further subdivided into a death subgroup and a survival subgroup based on the outcomes. The age, hospitalization costs, disease outcome indicators (e.g., mortality rate and incidence of septic shock), major organ (e.g., heart, liver, lungs, and kidneys) damage and their correlations, as well as PSS, Phoenix-8 and commonly used pediatric sepsis scores (e.g., pediatric sequential organ failure assessment (pSOFA), pediatric risk of mortality score Ⅲ (PRISM Ⅲ), pediatric logistic organ dysfunction-2 score (PELOD-2), pediatric multiple organ dysfunction score (P-MODS), pediatric critical illness score (PCIS), and pediatric early warning score (PEWS)) were collected and compared. Receiver operating characteristic (ROC) curve and precision-recall curve were plotted to evaluate the predictive ability of PSS, Phoenix-8, and commonly used pediatric sepsis scores for mortality risk in pediatric patients with severe sepsis under traditional standards. Predictive performance was quantified using the area under the ROC curve (AUROC). Univariate logistic regression analysis was employed to quantify the odds ratios of PSS and Phoenix-8 for predicting mortality risk. Patients with severe sepsis under traditional standards were further stratified into subgroups based on complications and comorbidities, including central nervous system (CNS) diseases, multiple infections, cardiovascular system diseases, shock, and malignancies. The Hosmer-Lemeshow goodness-of-fit test was used to assess calibration of PSS and Phoenix-8, and the DeLong test was used to compare whether there were statistically significant differences in the AUROC of PSS and Phoenix-8 for predicting mortality risk among different subgroups of pediatric patients. Results:Compared with those in non-sepsis group, pediatric patients in sepsis group were significantly older ( Z=-2.92, P<0.05) with higher incidences of septic shock and mortality, hospitalization costs, PRISM Ⅲ, PEWS, pSOFA, PELOD-2, PSS, and Phoenix-8 (with χ2 values of 21.28 and 13.64, respectively, Z values of -1.99, -5.33, -5.10, -8.55, -6.91, -10.98, and -9.93, respectively, P<0.05), and lower PCIS ( Z=-3.34, P<0.05). Compared with those in survival subgroup, hospitalization costs, PSS, Phoenix-8, PRISM Ⅲ, PEWS, pSOFA, PELOD-2, and P-MODS of pediatric patients in death subgroup was significantly higher (with Z values of -2.50, -3.50, -2.47, -5.11, -3.84, -2.94, -3.61, and -3.04, respectively, P<0.05). Compared with those in survival subgroup, the incidences of lung damage and liver damage of pediatric patients in death subgroup were also significantly higher (with χ2 values of 6.20 and 10.94, respectively, P<0.05), and 64.7% (97/150) of patients exhibited two or more concurrent organ damage. For predicting mortality risk in pediatric patients with severe sepsis under traditional standards, the AUROC values for PRISM Ⅲ, PCIS, PEWS, pSOFA, PELOD-2, P-MODS, PSS, and Phoenix-8 were approximately 0.70, with optimal cutoff values of 17.5, 91.0, 5.5, 4.5, 2.5, 4.5, 3.5, and 4.5, respectively; PELOD-2 demonstrated the highest sensitivity (0.83); while PRISM Ⅲ, PSS, and Phoenix-8 showed high specificity (>0.80). Univariate logistic regression analysis showed that for every 1-point increase in the PSS within 24 hours of pediatric intensive care unit admission, the relative risk of mortality increased by 63.7% (with odds ratio of 1.64, 95% confidence interval of 1.34-1.99, P<0.05). Similarly, for every 1-point increase in the Phoenix-8, the relative risk of mortality increased by 37.5% (with odds ratio of 1.38, 95% confidence interval of 1.18-1.60, P<0.05). The AUROC values (around 0.80) of PSS and Phoenix-8 for predicting mortality risk in pediatric patients with severe sepsis combined with CNS diseases, multiple infections, and cardiovascular system diseases were relatively high. In contrast, the AUROC values (0.60-0.80) for predicting mortality risk in pediatric patients with severe sepsis combined with shock or malignant tumors were moderate. All models passed the Hosmer-Lemeshow goodness-of-fit test ( P>0.05). The DeLong test indicated no statistically significant differences in predictive ability between PSS and Phoenix-8 across subgroups of pediatric patients ( P>0.05). Conclusions:PSS and Phoenix-8 exhibited higher specificity than most of the commonly used pediatric sepsis scores in predicting mortality risk under traditional standards. Both scores performed much better in predicting the mortality risk in pediatric patients with severe sepsis combined with CNS diseases, multiple infections, and cardiovascular system diseases.

A new method was developed for simultaneous and efficient determination of linear perfluorooctanoic acid(n-PFOA)and linear perfluorooctane sulfonate(n-PFOS),and their typical branched isomers in seawater by online solid phase extraction-liquid chromatography-tandem mass spectrometry(Online SPE-LC-MS/MS).Only centrifugation of the seawater sample was required to remove the particulate matter,and then the seawater sample was directly injected and analyzed by online SPE-LC-MS/MS.An Eclipse Plus-C18 guard column was selected as SPE column for online enrichment of linear and branched isomers,and a F5 PFP column(150 mm×2.1 mm,2.7 μm)was used as the analytical column.Under the optimized experimental conditions,the separation and detection of all PFOA and PFOS linear and branched isomers could be completed within 20 min.The spiked recoveries of various target compounds ranged from 82.9%to 107.7%with detection limits and limits of quantification of 0.10-1.05 ng/L and 0.30-2.11 ng/L,respectively.The method was characterized by good precision(RSD≤9.10%)and linearity(R2≥0.990).Subsequently,linear and branched isomers of PFOA and PFOS in surface and bottom seawater samples collected from the Laizhou Bay of China were determined.The results showed that the detection rate of all the four branched PFOA isomers were 100%,with the highest average concentration of 25.85 ng/L found for 6m-PFOA,which accounted for 11.79%of the∑PFOA.For the five branched isomers of PFOS,the highest detection rate of 90.84%was found for 5m-PFOS.The highest average concentration of 0.64 ng/L was observed for 3m-PFOS,accounting for 19.88%of ∑PFOS.The proposed method provided an effective detection tool for qualitative and quantitative detection of PFOA and PFOS isomers in the marine aquatic environment.

AIM:To investigate the effect of intrinsic specific transforming growth factor-β(TGF-β)signaling on regeneration and repair of myofibers in acute skeletal myositismice model induced by cardiotoxin(CTX).METHODS:One hundred and eighty-six wild C57BL/6 mice and one hundred and thirty-eight mice with conditional knockout of TGF-β receptor 2(TGF-βr2)in myofibers(SM TGF-βr2-/-mice)were selected.CTX injection to anterior tibial muscle(TA)in-duced acute myoinjury in mice.Some SM TGF-βr2-/-mice were given Smad signaling agonist SRI-011381(SRI)intramus-cular injection.All mice were mainly divided into the following groups:control group,SM TGF-βr2-/-group and SM TGF-βr2-/-+SRI group.Twenty-four mice were selected in each group.RT-qPCR and immunofluorescence staining were used to detect the relative mRNA level,protein expression of inflammatory cytokines and low-density lipoprotein receptor-related protein 1(LRP1),respectively,while the relative protein expression of myosin heavy chain 3(MHY3)and embryonic myosine heavy chain(eMHC)in damaged muscle was detected by Western blot and immunofluorescence staining.In vi-tro,after being extracted from neonatal mice,myogenic precursor cells(MPCs)were cultured in an pro-inflammatory mi-lieu and treated with SRI,recombinant mouse extracellular matrix protein 1(rmECM1)alone or in combination.Hereby,they were divided into the following seven groups:control-MPCs group,control-MPCs+LPS group,TGF-βr2-/--MPCs group,TGF-βr2-/--MPCs+LPS group,TGF-βr2-/--MPCs+LPS+SRI group,TGF-βr2-/--MPCs+LPS+rmECM1 group,and TGF-βr2-/--MPCs+LPS+SRI+rmECM1 group.Six mice were selected in each group.RT-qPCR and Western blot were used to detect the relative mRNA level,protein expression of major histocompatibility complex class I molecules(MHC-I/H-2Kb),major histocompatibility complex class II molecules(MHC-II/H2-Eα),Toll-like receptor 3(TLR3),and LRP1.And the relative protein expression of MoyD and myogenin in myotubes was detected by immunofluorescence staining.RE-SULTS:In vivo,compared with control group,SM TGF-βr2-/-group showed the significant upregulation of pro-inflamma-tory cytokines(P<0.05),and the opposite trend of anti-inflammatory cytokines,LRP1,MHY3,eMHC in the injured muscle(P<0.05),with delayed regeneration and repair of myofibers.In vitro,compared with control-MPCs+LPS group,LRP1,MoyD and myogenin significantly downregulated in TGF-βr2-/--MPCs+LPS group,but the downregulation trend was corrected after giving SRI treatment(P<0.05).In addition,compared with the TGF-βr2-/--MPCs+LPS group,the combi-nation of rmECM1 and SRI significantly upregulated the protein expression of MyoD and myogenin(P<0.05).CONCLU-SION:In a mouse model of acute skeletal myositis,intrinsic TGF-β signaling specifically in myofibers regulates local im-mune behavior.It promotes the expression of LRP1 in damaged muscle via Smad2/3 signaling,and LRP1 can then fully bind to ECM1,thereby facilitating muscle regeneration and repair,and improving the prognosis of acute skeletal myositis.

Aim To investigate the anti-acute lung injury(ALI)effect of Sterculiae Lychnophorae Semen(SLS)and its mechanism.Methods The main ac-tive components of SLS and their core targets and path-ways of action against ALI were obtained by network pharmacology methods.Subsequently,molecular doc-king technology and in vitro cellular experiments were applied for validation.Results A total of 19 core tar-gets were obtained,including HSP90AA1,CASP3,TNF,MAPK8 and MAPK14.The mechanisms may in-volve signaling pathways such as cancer,PI3K/Akt and MAPK.Molecular docking confirmed that the key targets of SLS formed a better binding activity with the relevant active ingredients.The in vitro results showed that SLS was able to protect the PM2.5-contaminated BEAS-2B cells,inhibit their NO,IL-1β and TNF-αlevels,and reduce the expression of p-p38 MAPK and p-JNK proteins.Conclusions The study successfully predicts the active ingredients,targets and signaling pathways of SLS against ALI,and in vitro experiments demonstrate that SLS might protect BEAS-2B cells from PM2.5 stimulus-induced inflammation and apoptosis by inhibiting the over-activation of p38 MAPK and JNK signaling pathways.

AIM:To investigate the effect of intrinsic specific transforming growth factor-β(TGF-β)signaling on regeneration and repair of myofibers in acute skeletal myositismice model induced by cardiotoxin(CTX).METHODS:One hundred and eighty-six wild C57BL/6 mice and one hundred and thirty-eight mice with conditional knockout of TGF-β receptor 2(TGF-βr2)in myofibers(SM TGF-βr2-/-mice)were selected.CTX injection to anterior tibial muscle(TA)in-duced acute myoinjury in mice.Some SM TGF-βr2-/-mice were given Smad signaling agonist SRI-011381(SRI)intramus-cular injection.All mice were mainly divided into the following groups:control group,SM TGF-βr2-/-group and SM TGF-βr2-/-+SRI group.Twenty-four mice were selected in each group.RT-qPCR and immunofluorescence staining were used to detect the relative mRNA level,protein expression of inflammatory cytokines and low-density lipoprotein receptor-related protein 1(LRP1),respectively,while the relative protein expression of myosin heavy chain 3(MHY3)and embryonic myosine heavy chain(eMHC)in damaged muscle was detected by Western blot and immunofluorescence staining.In vi-tro,after being extracted from neonatal mice,myogenic precursor cells(MPCs)were cultured in an pro-inflammatory mi-lieu and treated with SRI,recombinant mouse extracellular matrix protein 1(rmECM1)alone or in combination.Hereby,they were divided into the following seven groups:control-MPCs group,control-MPCs+LPS group,TGF-βr2-/--MPCs group,TGF-βr2-/--MPCs+LPS group,TGF-βr2-/--MPCs+LPS+SRI group,TGF-βr2-/--MPCs+LPS+rmECM1 group,and TGF-βr2-/--MPCs+LPS+SRI+rmECM1 group.Six mice were selected in each group.RT-qPCR and Western blot were used to detect the relative mRNA level,protein expression of major histocompatibility complex class I molecules(MHC-I/H-2Kb),major histocompatibility complex class II molecules(MHC-II/H2-Eα),Toll-like receptor 3(TLR3),and LRP1.And the relative protein expression of MoyD and myogenin in myotubes was detected by immunofluorescence staining.RE-SULTS:In vivo,compared with control group,SM TGF-βr2-/-group showed the significant upregulation of pro-inflamma-tory cytokines(P<0.05),and the opposite trend of anti-inflammatory cytokines,LRP1,MHY3,eMHC in the injured muscle(P<0.05),with delayed regeneration and repair of myofibers.In vitro,compared with control-MPCs+LPS group,LRP1,MoyD and myogenin significantly downregulated in TGF-βr2-/--MPCs+LPS group,but the downregulation trend was corrected after giving SRI treatment(P<0.05).In addition,compared with the TGF-βr2-/--MPCs+LPS group,the combi-nation of rmECM1 and SRI significantly upregulated the protein expression of MyoD and myogenin(P<0.05).CONCLU-SION:In a mouse model of acute skeletal myositis,intrinsic TGF-β signaling specifically in myofibers regulates local im-mune behavior.It promotes the expression of LRP1 in damaged muscle via Smad2/3 signaling,and LRP1 can then fully bind to ECM1,thereby facilitating muscle regeneration and repair,and improving the prognosis of acute skeletal myositis.

Aim To investigate the anti-acute lung injury(ALI)effect of Sterculiae Lychnophorae Semen(SLS)and its mechanism.Methods The main ac-tive components of SLS and their core targets and path-ways of action against ALI were obtained by network pharmacology methods.Subsequently,molecular doc-king technology and in vitro cellular experiments were applied for validation.Results A total of 19 core tar-gets were obtained,including HSP90AA1,CASP3,TNF,MAPK8 and MAPK14.The mechanisms may in-volve signaling pathways such as cancer,PI3K/Akt and MAPK.Molecular docking confirmed that the key targets of SLS formed a better binding activity with the relevant active ingredients.The in vitro results showed that SLS was able to protect the PM2.5-contaminated BEAS-2B cells,inhibit their NO,IL-1β and TNF-αlevels,and reduce the expression of p-p38 MAPK and p-JNK proteins.Conclusions The study successfully predicts the active ingredients,targets and signaling pathways of SLS against ALI,and in vitro experiments demonstrate that SLS might protect BEAS-2B cells from PM2.5 stimulus-induced inflammation and apoptosis by inhibiting the over-activation of p38 MAPK and JNK signaling pathways.

Objective:To explore the differences between the Phoenix sepsis scoring system including Phoenix sepsis score (PSS) and Phoenix-8 organ dysfunction score (hereinafter referred to as Phoenix-8) and the commonly used pediatric sepsis scores in evaluating clinical characteristics and prognostic analysis of pediatric patients with severe sepsis diagnosed under traditional standards, namely the diagnostic criteria from the 2005 International Pediatric Sepsis Consensus Conference.Methods:This study was a retrospective observational study. From December 2020 to March 2023, 202 pediatric patients with severe sepsis meeting the inclusion criteria were admitted to the Children's Hospital of Nanjing Medical University. Based on the sepsis diagnostic criteria outlined in the International Consensus Criteria for Pediatric Sepsis and Septic Shock (2024), the pediatric patients were categorized into a sepsis group and a non-sepsis group. Sepsis group was further subdivided into a death subgroup and a survival subgroup based on the outcomes. The age, hospitalization costs, disease outcome indicators (e.g., mortality rate and incidence of septic shock), major organ (e.g., heart, liver, lungs, and kidneys) damage and their correlations, as well as PSS, Phoenix-8 and commonly used pediatric sepsis scores (e.g., pediatric sequential organ failure assessment (pSOFA), pediatric risk of mortality score Ⅲ (PRISM Ⅲ), pediatric logistic organ dysfunction-2 score (PELOD-2), pediatric multiple organ dysfunction score (P-MODS), pediatric critical illness score (PCIS), and pediatric early warning score (PEWS)) were collected and compared. Receiver operating characteristic (ROC) curve and precision-recall curve were plotted to evaluate the predictive ability of PSS, Phoenix-8, and commonly used pediatric sepsis scores for mortality risk in pediatric patients with severe sepsis under traditional standards. Predictive performance was quantified using the area under the ROC curve (AUROC). Univariate logistic regression analysis was employed to quantify the odds ratios of PSS and Phoenix-8 for predicting mortality risk. Patients with severe sepsis under traditional standards were further stratified into subgroups based on complications and comorbidities, including central nervous system (CNS) diseases, multiple infections, cardiovascular system diseases, shock, and malignancies. The Hosmer-Lemeshow goodness-of-fit test was used to assess calibration of PSS and Phoenix-8, and the DeLong test was used to compare whether there were statistically significant differences in the AUROC of PSS and Phoenix-8 for predicting mortality risk among different subgroups of pediatric patients. Results:Compared with those in non-sepsis group, pediatric patients in sepsis group were significantly older ( Z=-2.92, P<0.05) with higher incidences of septic shock and mortality, hospitalization costs, PRISM Ⅲ, PEWS, pSOFA, PELOD-2, PSS, and Phoenix-8 (with χ2 values of 21.28 and 13.64, respectively, Z values of -1.99, -5.33, -5.10, -8.55, -6.91, -10.98, and -9.93, respectively, P<0.05), and lower PCIS ( Z=-3.34, P<0.05). Compared with those in survival subgroup, hospitalization costs, PSS, Phoenix-8, PRISM Ⅲ, PEWS, pSOFA, PELOD-2, and P-MODS of pediatric patients in death subgroup was significantly higher (with Z values of -2.50, -3.50, -2.47, -5.11, -3.84, -2.94, -3.61, and -3.04, respectively, P<0.05). Compared with those in survival subgroup, the incidences of lung damage and liver damage of pediatric patients in death subgroup were also significantly higher (with χ2 values of 6.20 and 10.94, respectively, P<0.05), and 64.7% (97/150) of patients exhibited two or more concurrent organ damage. For predicting mortality risk in pediatric patients with severe sepsis under traditional standards, the AUROC values for PRISM Ⅲ, PCIS, PEWS, pSOFA, PELOD-2, P-MODS, PSS, and Phoenix-8 were approximately 0.70, with optimal cutoff values of 17.5, 91.0, 5.5, 4.5, 2.5, 4.5, 3.5, and 4.5, respectively; PELOD-2 demonstrated the highest sensitivity (0.83); while PRISM Ⅲ, PSS, and Phoenix-8 showed high specificity (>0.80). Univariate logistic regression analysis showed that for every 1-point increase in the PSS within 24 hours of pediatric intensive care unit admission, the relative risk of mortality increased by 63.7% (with odds ratio of 1.64, 95% confidence interval of 1.34-1.99, P<0.05). Similarly, for every 1-point increase in the Phoenix-8, the relative risk of mortality increased by 37.5% (with odds ratio of 1.38, 95% confidence interval of 1.18-1.60, P<0.05). The AUROC values (around 0.80) of PSS and Phoenix-8 for predicting mortality risk in pediatric patients with severe sepsis combined with CNS diseases, multiple infections, and cardiovascular system diseases were relatively high. In contrast, the AUROC values (0.60-0.80) for predicting mortality risk in pediatric patients with severe sepsis combined with shock or malignant tumors were moderate. All models passed the Hosmer-Lemeshow goodness-of-fit test ( P>0.05). The DeLong test indicated no statistically significant differences in predictive ability between PSS and Phoenix-8 across subgroups of pediatric patients ( P>0.05). Conclusions:PSS and Phoenix-8 exhibited higher specificity than most of the commonly used pediatric sepsis scores in predicting mortality risk under traditional standards. Both scores performed much better in predicting the mortality risk in pediatric patients with severe sepsis combined with CNS diseases, multiple infections, and cardiovascular system diseases.

A new method for simultaneous determination of 23 kinds of per-and polyfluoroalkyl substances(PFASs)(13 kinds of perfluoro carboxylic acids,4 kinds of perfluoro sulfonic acids,and 6 kinds of new substitutes)in plant leaf tissue by ultra-high performance liquid chromatography-tandem mass spectrometry(UHPLC-MS/MS)using automatic online solid phase extraction(SPE)to remove the matrix interference components in plant crude extracts was developed.The plant leaf samples were extracted twice with 1%formic acid-methanol solution,then evaporated to dry,redissolved with 70%methanol solution,and directly injected for analysis.After 23 kinds of target PFASs were purified automatically by online SPE with a WAX column,the six-way valve was switched to rinse PFASs onto an alkaline mobile phase system-compatible C18 analytical column.Then,the 23 kinds of target PFASs were separated within 16 min by gradient elution using a binary mobile phase system of methanol/water(Containing 0.4%ammonium hydroxide).Tandem mass spectrometry was performed in multiple reaction monitoring(MRM)mode for online detection of various PFASs,and quantification was carried out by internal standard method.The results of the method validation showed that satisfactory average recoveries of 23 kinds of PFASs in plant leaf samples(64.2%-125.5%),precision(relative standard deviations(RSDs)of 0.7%-12.8%),linearity(R2＞0.990),and sensitivity(the detection limits(S/N=3)were in the range of 0.02-0.50 μg/kg)were achieved.Finally,this method was used to detect PFASs in the marine green tide algae(Enteromorpha prolifera)and several tree leaves,and a total of 6 kinds of PFASs were detected,in which PFBA was the main contaminant.Compared with the reported offline SPE methods,the proposed online SPE technique significantly simplified the sample pretreatment process and provided an automatic,simple,and environment-friendly method for the routine monitoring of legacy and emerging PFASs in plant tissues.

Objective To investigate the effect of E2 signaling in myofibers on muscular macrophage efferocytosis in mice with cardiotoxin-induced acute skeletal muscle injury.Methods Female wild-type C57BL/6 mice with and without ovariectomy and male C57BL/6 mice were given a CTX injection into the anterior tibial muscle to induce acute muscle injury,followed by intramuscular injection of β-estradiol(E2)or 4-hydroxytamoxifen(4-OHT).The changes in serum E2 of the mice were detected using ELISA,and the number,phenotypes,and efferocytosis of the macrophages in the inflammatory exudates and myofiber regeneration and repair were evaluated using immunofluorescence staining and flow cytometry.C2C12 cells were induced to differentiate into mature myotubes,which were treated with IFN-γ for 24 before treatment with β-Estradiol or 4-OHT.The treated myotubes were co-cultured with mouse peritoneal macrophages in a 1:2 ratio,followed by addition of PKH67-labeled apoptotic mouse mononuclear spleen cells induced by UV irradiation,and macrophage efferocytosis was observed using immunofluorescence staining and flow cytometry.Results Compared with the control mice,the female mice with ovariectomy showed significantly increased mononuclear macrophages in the inflammatory exudates,with increased M1 cell percentage,reduced M2 cell percentage and macrophage efferocytosis in the injured muscle,and obviously delayed myofiber regeneration and repair.In the cell co-culture systems,treatment of the myotubes with β-estradiol significantly increased the number and proportion of M2 macrophages and macrophage efferocytosis,while 4-OHT treatment resulted in the opposite changes.Conclusion In injured mouse skeletal muscles,myofiber E2 signaling promotes M1 to M2 transition to increase macrophage efferocytosis,thereby relieving inflammation and promoting muscle regeneration and repair.

Objective To investigate the effect of E2 signaling in myofibers on muscular macrophage efferocytosis in mice with cardiotoxin-induced acute skeletal muscle injury.Methods Female wild-type C57BL/6 mice with and without ovariectomy and male C57BL/6 mice were given a CTX injection into the anterior tibial muscle to induce acute muscle injury,followed by intramuscular injection of β-estradiol(E2)or 4-hydroxytamoxifen(4-OHT).The changes in serum E2 of the mice were detected using ELISA,and the number,phenotypes,and efferocytosis of the macrophages in the inflammatory exudates and myofiber regeneration and repair were evaluated using immunofluorescence staining and flow cytometry.C2C12 cells were induced to differentiate into mature myotubes,which were treated with IFN-γ for 24 before treatment with β-Estradiol or 4-OHT.The treated myotubes were co-cultured with mouse peritoneal macrophages in a 1:2 ratio,followed by addition of PKH67-labeled apoptotic mouse mononuclear spleen cells induced by UV irradiation,and macrophage efferocytosis was observed using immunofluorescence staining and flow cytometry.Results Compared with the control mice,the female mice with ovariectomy showed significantly increased mononuclear macrophages in the inflammatory exudates,with increased M1 cell percentage,reduced M2 cell percentage and macrophage efferocytosis in the injured muscle,and obviously delayed myofiber regeneration and repair.In the cell co-culture systems,treatment of the myotubes with β-estradiol significantly increased the number and proportion of M2 macrophages and macrophage efferocytosis,while 4-OHT treatment resulted in the opposite changes.Conclusion In injured mouse skeletal muscles,myofiber E2 signaling promotes M1 to M2 transition to increase macrophage efferocytosis,thereby relieving inflammation and promoting muscle regeneration and repair.