Ischemic stroke accounts for approximately 80% of all stroke cases worldwide and remains a leading cause of long‑term neurological disability and mortality. Intravenous thrombolysis and endovascular thrombectomy constitute the mainstay of acute reperfusion therapies, yet their clinical utility is severely constrained by narrow therapeutic time windows. Even when large‑vessel recanalization is successfully achieved, a considerable proportion of patients still suffer poor functional outcomes due to futile reperfusion and ischemia‑reperfusion injury. Historically, preclinical studies have largely focused on direct neuronal protection against calcium overload, oxidative stress and ferroptosis. Unfortunately, most promising neuroprotective agents that exhibited robust benefits in rodent models have failed to demonstrate satisfactory efficacy in phase‑Ⅱ and phase‑Ⅲ clinical trials. One critical contributor to such translational failure is the disregard for the pathological disturbance within the cerebral vascular microenvironment. Instead of merely regarding neuronal death as an autonomous cellular event, accumulating evidence indicates that sequential biochemical disruption of perivascular microenvironment acts as an initiating amplifier that propagates damage toward brain parenchyma after ischemic insult. The cerebral vascular microenvironment centers on brain microvessels and comprises endothelial cells, endothelial glycocalyx, basement membrane, pericytes, astrocytic end‑feet, perivascular microglia, as well as interstitial ions, inflammatory mediators, reactive oxygen species and extracellular matrix components. Distinct from the concept of neurovascular unit which emphasizes functional coupling between neurons, glia and vessels, the vascular microenvironment highlights dynamic biochemical homeostasis in perivascular interstitial space. Following cerebral ischemia, injured brain tissue can be spatially divided into the irreversibly damaged infarct core, metabolically‑stressed ischemic penumbra and mildly‑affected peripheral regions. These three zones lack rigid anatomical boundaries and evolve dynamically depending on reperfusion timing, presenting divergent features in blood perfusion, blood‑brain barrier integrity, cellular viability and immune‑inflammatory profiles. Four interrelated pathological cascades jointly disrupt microenvironmental homeostasis: calcium‑overload‑triggered cytotoxic cascades; blood‑brain barrier breakdown resulting from glycocalyx shedding, tight‑junction dissociation and matrix metalloproteinase‑driven basement‑membrane degradation; inflammatory‑immune dysregulation dominated by microglial phenotypic reprogramming; and mutual crosstalk between coagulation disturbance and neuroinflammation that exacerbates secondary brain injury. Multiple molecular layers orchestrate these pathological alterations. Excessive activation of HIF‑1α, NF‑κB and MAPK/ERK signaling pathways promotes barrier leakage, pro‑inflammatory factor secretion and extracellular‑matrix remodeling. Epigenetic modulation mediated by non‑coding RNAs including miRNAs and lncRNAs reshapes vascular microenvironment via three major patterns: modulating endothelial‑pericyte barrier integrity, switching microglia‑astrocyte inflammatory phenotypes, and driving metabolic reprogramming among multiple cell populations within microdomains. In addition, metabolic shift toward glycolysis among endothelial cells, microglia, astrocytes and compromised neurons establishes self‑amplifying vicious cycles of energy depletion and oxidative stress in perivascular niches. Targeted theranostic approaches oriented toward vascular microenvironment bring new opportunities for precision medicine of ischemic stroke. Magnetic nanoprobes and near‑infrared fluorescent probes respond to elevated reactive oxygen species, pH shift and inflammatory signals, enabling in situ visualization of pathological signatures of microenvironment and risk evaluation of hemorrhagic transformation. Function‑tailored nanodelivery systems exert multi‑modal protective effects: reactive oxygen species‑responsive polymeric micelles deliver calcium chelators to block calcium‑overload‑initiated injury cascades; nanozymes scavenge reactive oxygen/nitrogen species and revert microglial pro‑inflammatory polarization; biomimetic membrane‑coated nanoparticles accumulate at micro‑thrombosis sites to break thrombo‑inflammatory loops and mitigate no‑reflow phenomenon; ferroptosis‑inhibitor‑loaded nanocarriers eliminate excessive labile iron within perivascular toxic microdomains. During subacute and recovery phases, spatiotemporally controlled release of angiogenic factors by nanocarriers facilitates maturation of newly‑formed microvessels rather than blind vascular sprouting, which helps reconstruct intact blood‑brain barrier and restore microenvironmental homeostasis. Nevertheless, substantial translational bottlenecks still impede clinical transformation of these nanomedicines, including potential biosafety risks caused by in vivo material accumulation, protein‑corona‑induced impairment of targeting capacity, intrinsic blood brain barrier transport obstacles, lack of unified quality‑control criteria for large‑scale manufacture, reliance on high‑end clinical imaging instruments, and prominent interspecies discrepancies between experimental animals and human patients. On the basis of summarizing spatiotemporal pathological characteristics, multi‑level regulatory mechanisms and cutting‑edge microenvironment‑oriented diagnostic and interventional strategies, the present review advocates a conceptual shift from isolated neuronal protection to comprehensive reconstruction of perivascular vascular microenvironment homeostasis. Such perspective provides theoretical foundations for expanding therapeutic time windows and inspires future development of novel therapeutic modalities for ischemic stroke.

BACKGROUND:Relatively or absolutely active bone resorption function of osteoclasts is one of the causative factors of osteoporosis. Therefore,how to inhibit the formation of osteoclasts and reduce the bone resorption activity is a key element in the prevention and treatment of osteoporosis. Liquiritin,which is derived from licorice,plays a role in the clinical treatment of bone diseases,but there are fewer studies addressing the application of liquiritin in osteoporosis and the mechanism is unknown.OBJECTIVE:To confirm,through both in vivo and in vitro experiments,that liquiritin inhibits osteoclast differentiation and alleviates bone loss.METHODS:Cell counting kit-8 was used to detect whether Liquiritin exerts toxic or proliferative effects on mouse bone marrow-derived macrophages,and tartrate-resistant acid phosphatase staining was performed to observe the effect of liquiritin in inhibiting osteoclast differentiation. The affinity of liquiritin binding to proteins related to osteoclast differentiation was verified by network pharmacology. RT-PCR and western blot assays were performed to detect the inhibitory effects of liquiritin on osteoclast-specific protein and gene expression as well as relevant signaling pathways. Finally,the mitigating effect of liquiritin on bone loss was verified in the C57BL/6J mouse osteoporosis model.RESULTS AND CONCLUSION:Liquiritin,at concentrations of 20 μmol/L and below,could inhibit the formation and differentiation of osteoclasts. Concurrently,it exhibited a high affinity with osteoclast-specific proteins such as nuclear factor of activated T-cells 1,Cathepsin K,c-Fos,and matrix metalloproteinase 9,and reduced the relative expression levels of these genes and proteins. Liquiritin could also effectively lower the phosphorylation expression level of JNK in the MAPK signaling pathway at the 15th,30th,45th,and 60th minutes,and it could salvage the degradation of nuclear factor-κB inhibitor α in the nuclear factor-κB signaling pathway at the 60th minute. In vivo experiments demonstrated that liquiritin could mitigate bone loss caused by osteoclasts and improve parameters related to trabecular bone. To conclude,liquiritin possesses the capacity to inhibit osteoclast differentiation and alleviate bone loss,thereby exerting a protective role against osteoporosis.

Emodin is a hydroxyanthraquinone compound that is widely distributed and has multiple pharmacological activities, including anti-diarrheal, anti-inflammatory, and liver-protective effects. Research indicates that emodin may be one of the main components responsible for inducing hepatotoxicity. However, studies on the mechanisms of liver injury are relatively limited, particularly those related to bile acids(BAs) metabolism. This study aims to systematically investigate the effects of different dosages of emodin on BAs metabolism, providing a basis for the safe clinical use of traditional Chinese medicine(TCM)containing emodin. First, this study evaluated the safety of repeated administration of different dosages of emodin over a 5-week period, with a particular focus on its impact on the liver. Next, the composition and content of BAs in serum and liver were analyzed. Subsequently, qRT-PCR was used to detect the mRNA expression of nuclear receptors and transporters related to BAs metabolism. The results showed that 1 g·kg~(-1) emodin induced hepatic damage, with bile duct hyperplasia as the primary pathological manifestation. It significantly increased the levels of various BAs in the serum and primary BAs(including taurine-conjugated and free BAs) in the liver. Additionally, it downregulated the mRNA expression of farnesoid X receptor(FXR), retinoid X receptor(RXR), and sodium taurocholate cotransporting polypeptide(NTCP), and upregulated the mRNA expression of cholesterol 7α-hydroxylase(CYP7A1) in the liver. Although 0.01 g·kg~(-1) and 0.03 g·kg~(-1) emodin did not induce obvious liver injury, they significantly increased the level of taurine-conjugated BAs in the liver, suggesting a potential interference with BAs homeostasis. In conclusion, 1 g·kg~(-1) emodin may promote the production of primary BAs in the liver by affecting the FXR-RXR-CYP7A1 pathway, inhibit NTCP expression, and reduce BA reabsorption in the liver, resulting in BA accumulation in the peripheral blood. This disruption of BA homeostasis leads to liver injury. Even doses of emodin close to the clinical dose can also have a certain effect on the homeostasis of BAs. Therefore, when using traditional Chinese medicine or formulas containing emodin in clinical practice, it is necessary to regularly monitor liver function indicators and closely monitor the risk of drug-induced liver injury.
Emodin/administration & dosage* ; Bile Acids and Salts/metabolism* ; Animals ; Male ; Liver/injuries* ; Chemical and Drug Induced Liver Injury/genetics* ; Drugs, Chinese Herbal/adverse effects* ; Humans ; Rats, Sprague-Dawley ; Mice ; Rats

This study aims to explore the effects and action mechanisms of the active ingredients in Buyang Huanwu Decoction(BYHWD), namely tetramethylpyrazine(TMP) and hydroxy-safflor yellow A(HSYA), on oxygen-glucose deprivation/reglucose-reoxygenation(OGD/R)-induced inflammation and oxidative stress of microglia(MG). Network pharmacology was used to screen the effective monomer ingredients of BYHWD and determine the safe concentration range for each component. Inflammation and oxidative stress models were established to further screen the best ingredient combination and optimal concentration ratio with the most effective anti-inflammatory and antioxidant effects. OGD/R BV2 cell models were constructed, and BV2 cells in the logarithmic growth phase were divided into a normal group, a model group, an HSYA group, a TMP group, and an HSYA + TMP group. Enzyme-linked immunosorbent assay(ELISA) was used to detect the levels of inflammatory cytokines such as interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), and interleukin-6(IL-6). Oxidative stress markers, including superoxide dismutase(SOD), nitric oxide(NO), and malondialdehyde(MDA), were also measured. Western blot was used to analyze the protein expression of both inflammation-related pathway [Toll-like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB)] and oxidative stress-related pathway [nuclear factor erythroid 2-related factor 2(Nrf2)/heme oxygenase-1(HO-1)]. Immunofluorescence was used to assess the expression of proteins such as inducible nitric oxide synthase(iNOS) and arginase-1(Arg-1). The most effective ingredients for anti-inflammatory and antioxidant effects in BYHWD were TMP and HSYA. Compared to the normal group, the model group showed significantly increased levels of IL-1β, TNF-α, IL-6, NO, and MDA, along with significantly higher protein expression of NF-κB, TLR4, Nrf2, and HO-1 and significantly lower SOD levels. The differences between the two groups were statistically significant. Compared to the model group, both the HSYA group and the TMP group showed significantly reduced levels of IL-1β, TNF-α, IL-6, NO, and MDA, lower expression of NF-κB and TLR4 proteins, higher levels of SOD, and significantly increased protein expression of Nrf2 and HO-1. Additionally, the expression of the M1-type MG marker iNOS was significantly reduced, while the expression of the M2-type MG marker Arg-1 was significantly increased. The results of the HSYA group and the TMP group had statistically significant differences from those of the model group. Compared to the HSYA group and the TMP group, the HSYA + TMP group showed further significant reductions in IL-1β, TNF-α, IL-6, NO, and MDA levels, along with significant reductions in NF-κB and TLR4 protein expression, an increase in SOD levels, and elevated Nrf2 and HO-1 protein expression. Additionally, the expression of the M1-type MG marker iNOS was reduced, while the M2-type MG marker Arg-1 expression increased significantly in the HSYA + TMP group compared to the TMP or HSYA group. The differences in the results were statistically significant between the HSYA + TMP group and the TMP or HSYA group. The findings indicated that the combined use of HSYA and TMP, the active ingredients of BYHWD, can effectively inhibit OGD/R-induced inflammation and oxidative stress of MG, showing superior effects compared to the individual use of either component.
Oxidative Stress/drug effects* ; Drugs, Chinese Herbal/pharmacology* ; Animals ; Mice ; Glucose/metabolism* ; Cell Line ; Inflammation/genetics* ; Oxygen/metabolism* ; Pyrazines/pharmacology* ; Microglia/metabolism* ; NF-E2-Related Factor 2/immunology* ; NF-kappa B/immunology* ; Toll-Like Receptor 4/immunology* ; Anti-Inflammatory Agents/pharmacology* ; Humans

BACKGROUND:Studies have found that inhibition of tumor necrosis factor receptor-associated factor 6 improves myocardial function and promotes myocardial autophagy in sepsis,but the specific mechanism is not clear.OBJECTIVE:To explore the effect of inhibiting tumor necrosis factor receptor-associated factor 6-regulated mTORC1/ULK1 autophagy signaling pathway on myocardial injury in sepsis mice.METHODS:Thirty male Kunming mice were randomly divided into sham operation group,cecal ligation and puncture group(model group),model+tumor necrosis factor receptor-associated factor 6 specific inhibitor C25-140(model+C)group,model+C25-140+autophagy inhibitor 3-methyladenine(model+C+3-MA)group,and model+C25-140+mTORC1-specific agonist MHY1485(model+C+M)group.The cecum of mice in the sham operation group was not ligated or punctured.The mice in the other groups underwent cecum ligation and puncture to establish the mouse sepsis model.C25-140,3-methyladenine,and MHY1485 were intraperitoneally injected 0.5 hours after surgery according to the grouping.Myocardial tissue was obtained 24 hours after surgery.Hematoxylin-eosin staining was used to evaluate myocardial inflammatory lesions.Transmission electron microscopy was used to observe the changes in the autophagic bodies and mitochondrial microstructures of myocardial cells.TUNEL assay was used to detect myocardial cell apoptosis.PCR was used to detect the relative expression of tumor necrosis factor receptor-associated factor 6 mRNA.Western blot assay was used to detect the expression of related proteins.RESULTS AND CONCLUSION:(1)Compared with sham operation group,myocardial inflammatory cell infiltration and fibrous edema were observed in the model group.The mitochondria of the cells were obviously swollen,and autophagosomes were occasionally seen;cardiomyocyte apoptosis increased significantly;the expression of tumor necrosis factor receptor-associated factor 6,phosphorylated nuclear factor κB P65/P65,p-mTOR/mTOR,p-ULK1/ULK1,P62 and Bax protein increased,and the expression of Bcl2 protein decreased(P＜0.05).(2)Compared with the model group,myocardial inflammation and fibrous edema were alleviated in the model+C group.Myocardial mitochondrial swelling was reduced and autophagosomes increased;cardiomyocyte apoptosis decreased;the expression of phosphorylated nuclear factor κB P65/nuclear factor-κB P65,p-mTOR/mTOR,p-ULK1/ULK1,P62,and Bax protein decreased,while the Beclin-1 and Bcl2 protein increased(P＜0.05).(3)Compared with the model+C group,myocardial autophagosomes decreased and myocardial mitochondrial swelling was more obvious in the model+C+3-MA group.Myocardial inflammation was aggravated;myocardial cell apoptosis increased;the expression of phosphorylated nuclear factor κB P65/nuclear factor κB P65,P62,and Bax protein increased,and the Beclin-1 and Bcl2 protein decreased(P＜0.05).(4)Compared with the model+C group,the expression of p-mTOR/mTOR and p-ULK1/ULK1 in the model+C+M group increased,and the Beclin-1 and microtubule-associated protein 1 light chain 3 Ⅱ/Ⅰ protein expression decreased(P＜0.05).It is concluded that inhibition of tumor necrosis factor receptor-associated factor 6 regulates mTORC1/ULK1 autophagy signal to promote myocardial autophagy and participate in the protection of myocardial injury in sepsis.

To investigate the transcriptionally regulatory mechanism of the senp8 promoter in yellow cat-fish(Pelteobagrus fulvidraco);this study used P.fulvidraco as the research subject.Dual-luciferase re-porter assay and electrophoretic mobility shift assay were employed to analyze the functional activity of the promoter;coupled with in vivo experiments.The results indicated that the 2 045 bp senp8 promoter se-quence contained key transcription factor binding sites such as SP1;TATA-Box;CCAAT-Box;SREBP1;PPARα;and PPARγ.The binding sites of SREBP1(-901/-910 bp);PPARα(-1 291/-1 308 bp);and PPARγ(-1 292/-1 306 bp)in the senp8 promoter positively regulate its activity;and oleic acid or palmitic acid promote this binding.Furthermore;high-fat feeding promoted the expression of the senp8 gene and its protein in the liver of P.fulvidraco;oleic acid or palmitic acid treatment significantly en-hanced the activity of the senp8 promoter;and this enhancement could be achieved through the regulatory effects of SREBP1;PPARα;and PPARγ response elements.Additionally;high-fat feeding influenced the mRNA and protein expression levels of genes related to deSUMOylation modification in the liver of P.fulvidraco.This study provides new insights into the relationship between deSUMOylation modification and the regulation of lipid metabolism in the vertebrates.

BACKGROUND:Relatively or absolutely active bone resorption function of osteoclasts is one of the causative factors of osteoporosis. Therefore,how to inhibit the formation of osteoclasts and reduce the bone resorption activity is a key element in the prevention and treatment of osteoporosis. Liquiritin,which is derived from licorice,plays a role in the clinical treatment of bone diseases,but there are fewer studies addressing the application of liquiritin in osteoporosis and the mechanism is unknown.OBJECTIVE:To confirm,through both in vivo and in vitro experiments,that liquiritin inhibits osteoclast differentiation and alleviates bone loss.METHODS:Cell counting kit-8 was used to detect whether Liquiritin exerts toxic or proliferative effects on mouse bone marrow-derived macrophages,and tartrate-resistant acid phosphatase staining was performed to observe the effect of liquiritin in inhibiting osteoclast differentiation. The affinity of liquiritin binding to proteins related to osteoclast differentiation was verified by network pharmacology. RT-PCR and western blot assays were performed to detect the inhibitory effects of liquiritin on osteoclast-specific protein and gene expression as well as relevant signaling pathways. Finally,the mitigating effect of liquiritin on bone loss was verified in the C57BL/6J mouse osteoporosis model.RESULTS AND CONCLUSION:Liquiritin,at concentrations of 20 μmol/L and below,could inhibit the formation and differentiation of osteoclasts. Concurrently,it exhibited a high affinity with osteoclast-specific proteins such as nuclear factor of activated T-cells 1,Cathepsin K,c-Fos,and matrix metalloproteinase 9,and reduced the relative expression levels of these genes and proteins. Liquiritin could also effectively lower the phosphorylation expression level of JNK in the MAPK signaling pathway at the 15th,30th,45th,and 60th minutes,and it could salvage the degradation of nuclear factor-κB inhibitor α in the nuclear factor-κB signaling pathway at the 60th minute. In vivo experiments demonstrated that liquiritin could mitigate bone loss caused by osteoclasts and improve parameters related to trabecular bone. To conclude,liquiritin possesses the capacity to inhibit osteoclast differentiation and alleviate bone loss,thereby exerting a protective role against osteoporosis.

BACKGROUND:Studies have found that inhibition of tumor necrosis factor receptor-associated factor 6 improves myocardial function and promotes myocardial autophagy in sepsis,but the specific mechanism is not clear.OBJECTIVE:To explore the effect of inhibiting tumor necrosis factor receptor-associated factor 6-regulated mTORC1/ULK1 autophagy signaling pathway on myocardial injury in sepsis mice.METHODS:Thirty male Kunming mice were randomly divided into sham operation group,cecal ligation and puncture group(model group),model+tumor necrosis factor receptor-associated factor 6 specific inhibitor C25-140(model+C)group,model+C25-140+autophagy inhibitor 3-methyladenine(model+C+3-MA)group,and model+C25-140+mTORC1-specific agonist MHY1485(model+C+M)group.The cecum of mice in the sham operation group was not ligated or punctured.The mice in the other groups underwent cecum ligation and puncture to establish the mouse sepsis model.C25-140,3-methyladenine,and MHY1485 were intraperitoneally injected 0.5 hours after surgery according to the grouping.Myocardial tissue was obtained 24 hours after surgery.Hematoxylin-eosin staining was used to evaluate myocardial inflammatory lesions.Transmission electron microscopy was used to observe the changes in the autophagic bodies and mitochondrial microstructures of myocardial cells.TUNEL assay was used to detect myocardial cell apoptosis.PCR was used to detect the relative expression of tumor necrosis factor receptor-associated factor 6 mRNA.Western blot assay was used to detect the expression of related proteins.RESULTS AND CONCLUSION:(1)Compared with sham operation group,myocardial inflammatory cell infiltration and fibrous edema were observed in the model group.The mitochondria of the cells were obviously swollen,and autophagosomes were occasionally seen;cardiomyocyte apoptosis increased significantly;the expression of tumor necrosis factor receptor-associated factor 6,phosphorylated nuclear factor κB P65/P65,p-mTOR/mTOR,p-ULK1/ULK1,P62 and Bax protein increased,and the expression of Bcl2 protein decreased(P＜0.05).(2)Compared with the model group,myocardial inflammation and fibrous edema were alleviated in the model+C group.Myocardial mitochondrial swelling was reduced and autophagosomes increased;cardiomyocyte apoptosis decreased;the expression of phosphorylated nuclear factor κB P65/nuclear factor-κB P65,p-mTOR/mTOR,p-ULK1/ULK1,P62,and Bax protein decreased,while the Beclin-1 and Bcl2 protein increased(P＜0.05).(3)Compared with the model+C group,myocardial autophagosomes decreased and myocardial mitochondrial swelling was more obvious in the model+C+3-MA group.Myocardial inflammation was aggravated;myocardial cell apoptosis increased;the expression of phosphorylated nuclear factor κB P65/nuclear factor κB P65,P62,and Bax protein increased,and the Beclin-1 and Bcl2 protein decreased(P＜0.05).(4)Compared with the model+C group,the expression of p-mTOR/mTOR and p-ULK1/ULK1 in the model+C+M group increased,and the Beclin-1 and microtubule-associated protein 1 light chain 3 Ⅱ/Ⅰ protein expression decreased(P＜0.05).It is concluded that inhibition of tumor necrosis factor receptor-associated factor 6 regulates mTORC1/ULK1 autophagy signal to promote myocardial autophagy and participate in the protection of myocardial injury in sepsis.

To investigate the transcriptionally regulatory mechanism of the senp8 promoter in yellow cat-fish(Pelteobagrus fulvidraco);this study used P.fulvidraco as the research subject.Dual-luciferase re-porter assay and electrophoretic mobility shift assay were employed to analyze the functional activity of the promoter;coupled with in vivo experiments.The results indicated that the 2 045 bp senp8 promoter se-quence contained key transcription factor binding sites such as SP1;TATA-Box;CCAAT-Box;SREBP1;PPARα;and PPARγ.The binding sites of SREBP1(-901/-910 bp);PPARα(-1 291/-1 308 bp);and PPARγ(-1 292/-1 306 bp)in the senp8 promoter positively regulate its activity;and oleic acid or palmitic acid promote this binding.Furthermore;high-fat feeding promoted the expression of the senp8 gene and its protein in the liver of P.fulvidraco;oleic acid or palmitic acid treatment significantly en-hanced the activity of the senp8 promoter;and this enhancement could be achieved through the regulatory effects of SREBP1;PPARα;and PPARγ response elements.Additionally;high-fat feeding influenced the mRNA and protein expression levels of genes related to deSUMOylation modification in the liver of P.fulvidraco.This study provides new insights into the relationship between deSUMOylation modification and the regulation of lipid metabolism in the vertebrates.

Objective To investigate the distribution and antimicrobial resistance of bacterial isolates from blood samples in the hospitals participating in China Antimicrobial Surveillance Network (CHINET) from 2015 to 2021.Methods Bacterial strains isolated from blood samples were collected from 52 medical centers participating in CHINET from 2015 to 2021 for analysis of bacetrial distribution and antimicrobial resistance.Results A total of 153591 isolates were collected,48.8％ of which were gram-positive bacteria and 51.2％ were gram-negative bacteria.The top five bacterial strains were coagulase negative Staphylococcus (28.2％),Escherichia coli (20.7％),Klebsiella (13.7％),Enterococcus (7.2％),and Staphylococcus aureus (6.6％).Compard to female patients,male patients showed lower proportion of E.coli and higher proportions of other bacterial species in all the bacterial isolaets from blood samples.The proportions of Streptococcus pneumoniae and Salmonella in all the bacterial isolaets from blood samples were higher in children compared to adults.Enterobacterales species showed various resistance rates to antimicrobial agents.Overall,≥58.0％,≥36.8％ and ≥56.8％ of E.coli strains were resistant to cefotaxime,gentamicin and levofloxacin respectively over the 7-year period.However,less than 2.5％ of the E.coli strains were resistant to carbapenems.K.pneumoniae showed higher resistance rates to imipenem and meropenem than other Enterobacterales species.During the 7-year period,the prevalence of imipenem-resistant and meropenem-resistant K.pneumoniae increased from 21.4％ and 19.9％ in 2015 to 25.7％ and 26.6％ in 2021,respectively.However,carbapenems still maintained good antibacterial activity against other Enterobacterales,associaetd with lower resistance rates.In the 7-year period,Acinetobacter baumannii showed a dwonward trend in the resistance rates to imipenem and meropenem,but remained 72.9％ and 73.2％ respectively in 2021.The prevalence of imipenem-resistant and meropenem-resistant P.aeruginosa decreased from 26.7％ and 22.9％ in 2015 to 18.5％ and 14.7％ in 2021,respectively.The prevalence of PRSP was 1.5％ in the isolaets from adults and and 0.8％ in the isolates from children.Less than 3.0％ of the Enterococcus faecium and Enterococcus faecalis strains were resistant to vancomycin,teicolanin,or linezolid.The prevalence of methicillin-resistant S.aureus (MRSA) and coagulase negative Staphylococcus (MRCNS) was 32.1％ and 81.0％,respectively.The prevalence of MRSA was relatively stable,28.5％ in 2015 and 28.0％ in 2021.Conclusions Coagulase negative Staphylococcus,E.coli and K.pneumoniae were the main bacterial species isolated from blood samples in the hospitals participaing in the CHINET from 2015 to 2021.Significant sex and age differences were found in the distribution of bcterial isolates from blood samples.The overall resistance rates of the top bacetrial strains from blood samples to antimicrobial agents showed a downward trend.Ongoing surveillance of antimicrobial resistance for the isolates from blood samples is still essential for prescribing rational antimicrobial therapies and curbing bacterial resistance.