1.The Structure and Function of The YopJ Family Effectors in The Bacterial Type III Secretion System
Ao-Ning LI ; Wen-Bo LI ; Yu-Ying LU ; Min-Hui ZHU ; Yu-Long QIN ; Yong ZHAO ; Zhao-Huan ZHANG
Progress in Biochemistry and Biophysics 2026;53(3):516-533
The Type III Secretion System (T3SS) serves as a pivotal virulence apparatus for numerous Gram-negative bacterial pathogens, enabling them to infect both animal and plant hosts. Functioning as a molecular syringe, the T3SS directly translocates bacterial effector proteins from the bacterial cytoplasm into the interior of eukaryotic host cells. These effectors are central weapons that precisely manipulate a wide spectrum of host cellular physiological processes, ranging from cytoskeletal dynamics to immune signaling, to establish a favorable niche for bacterial survival and proliferation. Among the diverse arsenal of T3SS effectors, the YopJ family constitutes a critical group of virulence factors. Members of this family are characterized by a conserved catalytic triad structure—a hallmark of the CE clan of cysteine proteases that has been evolutionarily repurposed to confer acetyltransferase activity. A defining and intriguing feature of these enzymes is their stringent dependence on a host-derived eukaryotic cofactor, inositol hexakisphosphate (IP6), for allosteric activation. This requirement acts as a sophisticated molecular safeguard, ensuring enzymatic activity only within the appropriate host environment, thereby preventing detrimental effects on the bacterium itself. While seminal studies on individual members such as Yersinia’s YopJ and Salmonella’s AvrA have provided deep mechanistic insights, a systematic and integrative understanding of the structure-function relationships across the entire family remains fragmented. Key questions persist regarding how a conserved catalytic core has diverged to recognize distinct host substrates in different kingdoms of life. To address this gap, this article provides a systematic review of the YopJ family, focusing on three interconnected aspects: their structural features, their catalytic mechanism, and their divergent immunosuppressive strategies in animal versus plant hosts. By conducting a comparative analysis of the sequences and resolved three-dimensional structures of three representative members (e.g., HopZ1a, PopP2, AvrA), we elucidate regions of significant variation embedded within the conserved core catalytic architecture. These variable regions, often involving surface loops and substrate-binding interfaces, are crucial determinants of target specificity and functional specialization. The functional divergence of this effector family is most apparent when comparing their modes of action in different hosts. In animal hosts, YopJ-family effectors primarily sabotage innate immune signaling pathways. They achieve this by acetylating key serine and threonine residues within the activation loops of critical kinases in the MAPK and NF‑κB pathways. This post-translational modification blocks the phosphorylation and subsequent activation of these kinases, leading to potent suppression of inflammatory cytokine production. Conversely, in plant hosts, the strategy broadens to dismantle the two-tiered plant immune system. YopJ homologs target a more diverse set of substrates, including immune-associated receptor-like cytoplasmic kinases (RLCKs), microtubule networks via tubulin acetylation (which disrupts cellular trafficking and signaling), and transcription factors central to defense gene regulation. This multi-target approach effectively suppresses both Pattern-Triggered Immunity (PTI) and Effector-Triggered Immunity (ETI). In conclusion, this synthesis aims to deepen the mechanistic understanding of YopJ family-mediated pathogenesis by integrating structural biology with cellular function across host kingdoms. Elucidating the precise molecular basis for substrate selection—how conserved platforms achieve target diversity—is a major frontier. Furthermore, this knowledge provides a vital theoretical foundation for developing novel anti-virulence strategies. Targeting the conserved IP6-binding pocket or the catalytic acetyltransferase activity itself represents a promising avenue for designing broad-spectrum inhibitors that could disarm this critical family of bacterial effectors, potentially offering new therapeutic approaches against a range of pathogenic bacteria.
2.Suppression of Hepatocellular Carcinoma through Apoptosis Induction by Total Alkaloids of Gelsemium elegans Benth.
Ming-Jing JIN ; Yan-Ping LI ; Huan-Si ZHOU ; Yu-Qian ZHAO ; Xiang-Pei ZHAO ; Mei YANG ; Mei-Jing QIN ; Chun-Hua LU
Chinese journal of integrative medicine 2025;31(9):792-801
OBJECTIVE:
To evaluate the anti-hepatocellular carcinoma (HCC) activity of total alkaloids from Gelsemium elegans Benth. (TAG) in vivo and in vitro and to elucidate their potential mechanisms of action through transcriptomic analysis.
METHODS:
TAG extraction was conducted, and the primary components were quantified using high-performance liquid chromatography (HPLC). The effects of TAG (100, 150, and 200 µg/mL) on various tumor cells, including SMMC-7721, HepG2, H22, CAL27, MCF7, HT29, and HCT116, were assessed. Effects of TAG on HCC proliferation and apoptosis were detected by colony formation assays and cell stainings. Caspase-3, Bcl-2, and Bax protein levels were detected by Western blotting. In vivo, a tumor xenograft model was developed using H22 cells. Totally 40 Kunming mice were randomly assigned to model, cyclophosphamide (20 mg/kg), TAG low-dose (TAG-L, 0.5 mg/kg), and TAG high-dose (TAG-H, 1 mg/kg) groups, with 10 mice in each group. Tumor volume, body weight, and tumor weight were recorded and compared during 14-day treatment. Immune organ index were calculated. Tissue changes were oberseved by hematoxylin and eosin staining and immunohistochemistry. Additionally, transcriptomic and metabolomic analyses, as well as quatitative real-time polymerase chain reaction (RT-qPCR), were performed to detect mRNA and metabolite expressions.
RESULTS:
HPLC successfully identified the components of TAG extraction. Live cell imaging and analysis, along with cell viability assays, demonstrated that TAG inhibited the proliferation of SMMC-7721, HepG2, H22, CAL27, MCF7, HT29, and HCT116 cells. Colony formation assays, Hoechst 33258 staining, Rhodamine 123 staining, and Western blotting revealed that TAG not only inhibited HCC proliferation but also promoted apoptosis (P<0.05). In vivo experiments showed that TAG inhibited the growth of solid tumors in HCC in mice (P<0.05). Transcriptomic analysis and RT-qPCR indicated that the inhibition of HCC by TAG was associated with the regulation of the key gene CXCL13.
CONCLUSION
TAG inhibits HCC both in vivo and in vitro, with its inhibitory effect linked to the regulation of the key gene CXCL13.
Animals
;
Apoptosis/drug effects*
;
Liver Neoplasms/genetics*
;
Carcinoma, Hepatocellular/genetics*
;
Humans
;
Alkaloids/therapeutic use*
;
Gelsemium/chemistry*
;
Cell Line, Tumor
;
Cell Proliferation/drug effects*
;
Mice
;
Xenograft Model Antitumor Assays
3.Suanzaoren Decoction Alleviates Anxiety- and Depression-Like Behaviors Induced by Chronic Restraint Stress via Regulating Pyramidal Neuron Activity in Basolateral Amygdala of Mice.
Chang-Feng CHEN ; Yin-Huan GAO ; Qin FANG ; Yong-Feng ZHOU ; Yong LIU ; Jian WU ; Hao CHEN ; Lie-Cheng WANG ; Lei CHEN
Chinese journal of integrative medicine 2025;31(11):982-990
OBJECTIVE:
To elucidate the modulation mechanism of Suanzaoren Decoction (SZRD) on basolateral amygdala (BLA) neuronal activity to alleviate chronic restraint stress (CRS)-related behavioral deficits.
METHODS:
The male C57BL/6J mice were assigned to 4 groups using the complete randomization method, including control (CON, n=19), CRS (n=19), SZRD (n=21), and fluoxetine (Flu, n=22) groups. Mice were restrained for 6 h per day, over a 21-d period to establish CRS models. The CON group remained in their cages without food or water during the 6-h matching period. SZRD and Flu groups received intragastric administration of SZRD (4.68 g/kg) and Flu (20 mg/kg) daily, respectively, 30 min before restraint for 21 consecutive days. The therapeutic effects of SZRD were evaluated using behavioral tests including the tail suspension test, elevated plus maze test, and forced swimming test. The cellular Fletcher B. Judson murine osteosarcoma proto-oncogene (c-Fos) expression in the BLA was measured using immunofluorescence, while action potential (AP) firing and synaptic transmission in BLA pyramidal neurons were evaluated using whole-cell patch-clamp recordings.
RESULTS:
SZRD administration significantly increased time spent in the open arms and open-arm entries while reducing immobility time (P<0.05 or P<0.01). It downregulated CRS-induced c-Fos expression and AP firing of pyramidal neurons in the BLA (P<0.01). Additionally, SZRD selectively attenuated excitatory (P<0.01), but not inhibitory, synaptic transmission onto BLA pyramidal neurons.
CONCLUSION
SZRD alleviated CRS-induced anxiety- and depression-like behaviors in mice by modulating the excitability and synaptic transmission of BLA pyramidal neurons.
Animals
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Drugs, Chinese Herbal/therapeutic use*
;
Depression/complications*
;
Pyramidal Cells/pathology*
;
Male
;
Mice, Inbred C57BL
;
Basolateral Nuclear Complex/pathology*
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Restraint, Physical
;
Anxiety/complications*
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Behavior, Animal/drug effects*
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Stress, Psychological/physiopathology*
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Mice
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Proto-Oncogene Proteins c-fos/metabolism*
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Action Potentials/drug effects*
;
Synaptic Transmission/drug effects*
4.Particulate matter exposure and end-stage renal disease risk in IgA nephropathy.
Yilin CHEN ; Huan ZHOU ; Siqing WANG ; Lingqiu DONG ; Yi TANG ; Wei QIN
Frontiers of Medicine 2025;19(5):855-864
Long-term exposure to particulate matter has been increasingly implicated in the progression of chronic kidney disease (CKD). However, its impact on IgA nephropathy (IgAN), a leading cause of end-stage renal disease (ESRD), remains unclear. A total of 1768 IgAN patients, confirmed by renal biopsy were included in this cohort study. Long-term exposure to PM2.5 and PM10 was assessed using high-resolution satellite-based data from the China High Air Pollutants (CHAP) dataset. Cox proportional hazards models were used to estimate the associations between PM2.5 or PM10 and ESRD risk, adjusting for demographic, clinical, and biochemical covariates. Over a median follow-up of 3.63 years, 209 participants progressed to ESRD. Higher exposure to both PM2.5 and PM10 was significantly associated with an increased risk, with hazard ratios of 1.62 and 1.36 per 10 µg/m3 increase, respectively. A nonlinear dose-response relationship was observed, with risk increasing markedly beyond threshold levels. Trajectory modeling of prebaseline exposure identified a subgroup with persistently high and fluctuating particulate matter exposure that showed the highest risk. This study provides strong evidence that prolonged exposure to ambient particulate matter contributes to renal disease progression in individuals with IgAN.
Humans
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Glomerulonephritis, IGA/pathology*
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Particulate Matter/adverse effects*
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Male
;
Female
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Kidney Failure, Chronic/epidemiology*
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Adult
;
China/epidemiology*
;
Disease Progression
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Environmental Exposure/adverse effects*
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Middle Aged
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Proportional Hazards Models
;
Risk Factors
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Air Pollutants/adverse effects*
;
Cohort Studies
5.Research progress on multi-omics biomarkers in Sjogren's syndrome.
Xueqin ZHOU ; Huan LI ; Zhina ZHAO ; Qin LI ; Bingsen WANG ; Songwei LI
Chinese Journal of Cellular and Molecular Immunology 2025;41(10):921-928
Sjogren's syndrome (SS) is a common autoimmune disorder that primarily targets exocrine glands, leading to hallmark manifestations of xerostomia and xerophthalmia, with potential progression to multisystem involvement. The rapid advances in omics technologies-including metabolomics, proteomics, and transcriptomics-have yielded substantial insights into SS pathophysiology. This review consolidates current evidence on omics-derived biomarkers in SS. Studies consistently implicate aberrant glucose metabolism, neutrophil-derived enzyme activity, mitochondrial bioenergetic impairment, ferroptosis, and apoptotic pathways as central to SS development. These findings refine our understanding of disease mechanisms and the heterogeneity of therapeutic responses. Hydroxyproline has emerged as a candidate marker for distinguishing SS from IgG4-related disease, whereas distinct cytokine and chemokine signatures may enable earlier diagnosis. Genomic analyses demonstrate a robust association between expression of the rs11797 locus and SS-related lymphomagenesis, and several genes controlling DNA methylation represent promising therapeutic targets. Collectively, these findings lay the groundwork for personalized risk stratification and intervention in SS. The review concludes by summarizing existing progress and outlining priorities for future omics-based investigations.
Humans
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Sjogren's Syndrome/diagnosis*
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Biomarkers/analysis*
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Metabolomics/methods*
;
Proteomics/methods*
;
Genomics
;
Multiomics
6.Association of angiotensin Ⅱ type 1 receptor autoantibody and sperm motility in human semen.
Dao-Qin TU ; Yu-Huan YANG ; Gui-Fang YANG ; Yi-Nan ZHANG ; Yao CHEN ; Xue-Ming LI ; Yu-Hui SHI ; Xiao-Li YANG ; Feng WANG
National Journal of Andrology 2025;31(5):387-394
OBJECTIVE:
To investigate the relationship between angiotensin Ⅱ type 1 receptor autoantibody (AT1-AA) and semen parameters. Methods: The semen samples of 820 male patients who were treated in the Reproductive Medicine Center of Taiyuan Central Hospital from August 2022 to August 2023 were retrospectively analyzed. The levels of AT1-AA and Ang Ⅱ of semen were detected by ELISA, and the function of AT1-AA was detected by cardiomyocyte beating assay in suckling rats. The patients were divided into low group, median group and high group according to the OD values of AT1-AA. The differences in general data and semen parameters between different groups were analyzed. And the correlation between AT1-AA level and semen parameters in semen of all study subjects was analyzed by the method of Spearman analysis. And the relationships between AT1-AA OD value, Ang Ⅱ level and semen parameters in the AT1-AA high value group were analyzed as well.
RESULTS:
AT1-AA was present in semen with good function. There was no significant difference in the general data of patients in different AT1-AA levels (P>0.05). In the comparison of semen parameters among the groups with different levels of AT1-AA, there were differences in sperm concentration, PR concentration, NP%, and ALH among the three groups (P<0.05). And AT1-AA OD value was positively correlated with total sperm count, sperm concentration, PR concentration, and NP%, and negatively correlated with semen volume (P<0.05). In the AT1-AA high value group, the OD value of AT1-AA in semen was negatively correlated with inactive sperm, and positively correlated with total motility ([PR+NP]%), curve rate, mean path rate, and ALH. However, there was no correlation between the level of Ang Ⅱ in semen and semen parameters (P>0.05).
CONCLUSION
The presence of AT1-AA in semen may be associated with the promotion of sperm motility.
Male
;
Humans
;
Autoantibodies
;
Sperm Motility
;
Semen
;
Retrospective Studies
;
Receptor, Angiotensin, Type 1/immunology*
;
Animals
;
Rats
;
Angiotensin II
;
Adult
;
Sperm Count
;
Semen Analysis
;
Receptor, Angiotensin, Type 2/immunology*
7.Short-term effects of ambient ozone on pediatric pneumonia hospital admissions: a multi-city case-crossover study in China.
Huan WANG ; Huan-Ling ZENG ; Guo-Xing LI ; Shuang ZHOU ; Jin-Lang LYU ; Qin LI ; Guo-Shuang FENG ; Hai-Jun WANG
Environmental Health and Preventive Medicine 2025;30():75-75
BACKGROUND:
Children's respiratory health demonstrates particular sensitivity to air pollution. Existing evidence investigating the association between short-term ozone (O3) exposure and childhood pneumonia remains insufficient and inconsistent, especially in low- and middle-income countries (LMICs).
METHOD:
To provide more reliable and persuasive evidence, we implemented a multi-city, time-stratified case-crossover design with a large sample size, using data from seven representative children's hospitals across major geographical regions in China. To avoid the impact of the COVID-19 pandemic, individual-level medical records of inpatient children under 6 years of age diagnosed with pneumonia during 2016-2019 were collected. Conditional logistic regression models were fitted for each city, and city-specific estimates were pooled through a meta-analysis using a random-effects model.
RESULTS:
In total, the study included 137,470 pediatric pneumonia hospital admissions. The highest pooled estimate for O3 occurred at lag0-1, with a 10 µg/m3 increase in O3 associated with a 1.57% (95% CI: 0.67%-2.48%) higher risk of pediatric pneumonia hospital admissions. Stratified analyses indicated that the effects of O3 were robust across different sexes, age groups, and admission seasons. We also observed a statistically significant increase in risk associated with O3 concentrations exceeding the World Health Organization Air Quality Guidelines (WHO-AQGs).
CONCLUSIONS
This study revealed a significant positive association between O3 and pediatric pneumonia hospital admissions. Our findings substantially strengthen the evidence base for the adverse health impacts of O3, underscoring the importance of O3 pollution control and management in reducing the public health burden of pediatric pneumonia.
Humans
;
Ozone/analysis*
;
China/epidemiology*
;
Pneumonia/chemically induced*
;
Child, Preschool
;
Male
;
Female
;
Infant
;
Cross-Over Studies
;
Air Pollutants/analysis*
;
Hospitalization/statistics & numerical data*
;
Child
;
Cities/epidemiology*
;
Air Pollution/adverse effects*
;
Infant, Newborn
;
Environmental Exposure/adverse effects*
8.Health economics evaluation of inoculation of children with type b Haemophilus influenzae vaccine
Sisi CHEN ; Lu YANG ; Tian TANG ; Xinping ZHANG ; Huan QIN ; Chengfeng XIE ; Yi ZENG ; Fei CAO ; Hongying LI ; Feina DENG ; Zhengbo TU ; Xiuwen CHEN
Chinese Journal of Nosocomiology 2025;35(17):2651-2655
OBJECTIVE T o carry out the health economics evaluation and cost-benefit analysis of the type b Hae-mophilus influenzae(Hib)vaccination for the children who were hospitalized due to Hib infection so as to provide evidence for public health policies.METHODS The children who were diagnosed with Hib-related respiratory tract infections or meningitis and were hospitalized in respiratory medicine department,infection management depart-ment,emergency rooms and neurology department of Jiangxi Provincial Children's Hospital from Jan.1,2021 to Dec.31,2023 were recruited as the research subjects.Based on a 1∶1 matching condition,the matching variables included four items such as the same age for the admission to the hospital,same gender,same department and same grade of disease severity.The children for whom the primary immunization of Hib vaccination(including Hib monovalent vaccine and Hib-containing combination vaccine)were completed and the integrity of vaccination infor-mation could be checked out were assigned as the intervention group,while the children for whom the primary im-munization of Hib vaccination was not completed were chosen as the control group.The clinical data,vaccination data and the data such as length of hospital stay and hospitalization cost were collected from the children.The cost-benefit of the Hib vaccination among the children with Hib infection was observed.RESULTS A total of 622 hospi-talized children who were detected with Hib-positive respiratory tract infections or meningitis were enrolled in the study,and 73 children(20 children from infection management department,27 children from respiratory medi-cine department,26 children from emergency rooms)were finally included in the intervention group after matc-hing and multiple rounds of screening,73 children were chosen as the control group based on a 1∶1 matching con-dition.The male children accounted for 57.53%(42 cases)in both groups,and the female children accounted for 42.47%(31 cases)in both groups.With the respect to the length of hospital stay,it was 7.00(5.00,8.00)days in the intervention group,7.00(6.00,8.00)days in the control group(Z=-0.341,P=0.733).In terms of the hospitalization cost,it was 7 756.17(6 617.92,10 617.69)yuan in the intervention group,9 040.65(8 033.76,10 935.84)yuan in the control group(Z=-2.795,P=0.005).The cost of Hib vaccination was 343.03 yuan per capita in the intervention group,and the benefit-cost ratio(BCR)was 1∶3.74(343.03 yuan/1 284.48 yuan).CONCLUSIONS The Hib vaccination can save the hospitalization cost and has high cost effectiveness.It is sugges-ted that the Hib vaccination should be promoted and the coverage rate of Hib vaccination should be raised among the age-eligible children.
9.Efficacy and safety of coblopasvir hydrochloride capsules/sofosbuvir tablets with or without ribavirin tablets in treatment of patients with chronic hepatitis C virus infection
Chunyan MOU ; Danqing XU ; Huan MU ; Jiangyan ZHANG ; Lixian CHANG ; Yuanqiang HE ; Yingyuan ZHANG ; Weikun LI ; Xiuling ZHANG ; Xiliang HE ; Qin PENG ; Li LIU
Journal of Clinical Hepatology 2025;41(9):1779-1787
ObjectiveTo investigate the therapeutic efficacy, influencing factors, and safety of a treatment regimen based on coblopasvir hydrochloride capsules/sofosbuvir tablets in patients with chronic hepatitis C virus (HCV) infection in a real-world setting. MethodsA total of 253 patients who attended The Third People’s Hospital of Kunming from September 1, 2021 to May 31, 2024 were enrolled, among whom there were 86 patients with compensated liver cirrhosis (CLC group) and 167 patients with chronic hepatitis C (CHC group). The patients were treated with coblopasvir hydrochloride capsules (60 mg)/sofosbuvir tablets (400 mg) with or without ribavirin tablets for 12 weeks, and they were followed up for 12 weeks after drug withdrawal. The primary outcome measures were the rate of sustained virologic response at week 12 after treatment (SVR12) and safety, and the secondary outcome measures were the changes in liver function, renal function, blood routine, and liver stiffness measurements (LSM) after 4 weeks of treatment, after 12 weeks of treatment, and at 12 weeks after drug withdrawal. The independent-samples t test and the Mann-Whitney U test were used for comparison of continuous data between two groups, and the Friedman test was used for comparison between multiple groups, while the Bonferroni method was used for paired comparison within each group; the chi-square test was used for comparison of categorical data between two groups. The Logistic analysis was used to investigate related influencing factors. ResultsThe 253 patients with chronic HCV infection had a mean age of 49.38±8.65 years, and there were 151 male patients (59.7%). Of all patients, 33.99% (86/253) had liver cirrhosis, 25.69% (65/253) had hypertension, 10.67% (27/253) had HIV infection, 8.70% (22/253) had diabetes, 3.95% (10/253) had liver cancer, 1.98% (5/253) had chronic hepatitis B, and 7.91% (20/253) were treatment-experienced patients. As for genotype distribution, 2.77% (7/253) had genotype 1, 12.65% (32/253) had genotype 2, 66.01% (167/253) had genotype 3, 16.60% (42/253) had genotype 6, and 1.98% (5/253) had unknown genotype. The patients had an overall SVR12 rate of 92.09%, with an SVR12 rate of 93.02% in the CLC group and 91.02% in the CHC group. The multivariate logistic regression analysis showed that age (odds ratio [OR]=1.086, 95% confidence interval [CI]: 1.007 — 1.170, P=0.032) and HCC (OR=9.178, 95%CI: 1.722 — 48.912, P=0.009) were independent influencing factors for sustained virologic response. Compared with baseline data, the CLC group had significant reductions in alanine aminotransferase (ALT) (χ2=107.103, P0.05), aspartate aminotransferase (AST) (χ2=90.602, P0.05), and LSM (χ2=42.235, P0.05) after 12 weeks of treatment, while the CHC group had significant reductions in total bilirubin (χ2=15.113, P0.05), ALT (χ2=202.237, P0.05), AST (χ2=161.193, P0.05), and LSM (χ2=37.606, P0.05). The incidence rate of serious adverse events was 1.58%, and none of the patients withdrew from drug therapy; the patients with such events were relieved after active symptomatic treatment. The incidence rate of all adverse events was 23.72%, among which fatigue (17.39%) and nausea (2.37%) were the most common adverse events, and these events often disappeared within 2 weeks or were gradually relieved after symptomatic treatment. ConclusionCoblopasvir hydrochloride capsules/sofosbuvir tablets with or without ribavirin tablets has good efficacy and safety in the treatment of chronic HCV infection.
10.The Role and Mechanism of Aerobic Exercise in Enhancing Insulin Sensitivity by Reducing Circulating Glutamate
Xiao-Rui XING ; Qin SUN ; Huan-Yu WANG ; Ruo-Bing FAN ; Ru WANG
Progress in Biochemistry and Biophysics 2025;52(6):1373-1385
ObjectiveTo explore the role and potential mechanism of circulating glutamate in enhancing insulin sensitivity by aerobic exercise. This research may provide a novel strategy for preventing metabolic diseases through precise exercise interventions. MethodsTo investigate the effects of elevated circulating glutamate on insulin sensitivity and its potential mechanisms, 18 male C57BL/6 mice aged 6 to 8 weeks were randomly divided into 3 groups: a control group (C), a group receiving 500 mg/kg glutamate supplementation (M), and a group receiving 1 000 mg/kg glutamate supplementation (H). The intervention lasted for 12 weeks, with treatments administered 6 d per week. Following the intervention, an insulin tolerance test (ITT) and a glucose tolerance test (GTT) were conducted. Circulating glutamate levels were measured using a commercial kit, and the activity of the skeletal muscle InsR/IRS1/PI3K/AKT signaling pathway was analyzed via Western blot. To further investigate the role of circulating glutamate in enhancing insulin sensitivity through aerobic exercise, 30 male C57BL/6 mice were randomly assigned to 3 groups: a control group (CS), an exercise intervention group (ES), and an exercise combined with glutamate supplementation group (EG). The ES group underwent treadmill-based aerobic exercise, while the EG group received glutamate supplementation at a dosage of 1 000 mg/kg in addition to aerobic exercise. The intervention lasted for 10 weeks, with sessions occurring 6 d per week, and the same procedures were followed afterward. To further elucidate the mechanism by which glutamate modulates the InsR/IRS1/PI3K/AKT signaling pathway, C2C12 myotubes were initially subjected to graded glutamate treatment (0, 0.5, 1, 3, 5, 10 mmol/L) to determine the optimal concentration for cellular intervention. Subsequently, the cells were divided into 3 groups: a control group (C), a glutamate intervention group (G), and a glutamate combined with MK801 (an NMDA receptor antagonist) intervention group (GK). The G group was treated with 5 mmol/L glutamate, while the GK group received 50 μmol/L MK801 in addition to 5 mmol/L glutamate. After 24 h of intervention, the activity of the InsR/IRS1/PI3K/AKT signaling pathway was analyzed using Western blot. ResultsCompared to the mice in group C, the circulating glutamate levels, the area under curve (AUC) of ITT, and the AUC of GTT in the mice of group H were significantly increased. Additionally, the expression levels of p-InsRβ, IRS1, p-AKT, and p-mTOR proteins in skeletal muscle were significantly downregulated. Compared to the mice in group CS, the circulating glutamate levels, the AUC of ITT, and the AUC of GTT in the mice of group ES were significantly reduced. Additionally, the expression levels of p-InsRβ, IRS1, p-AKT, and p-mTOR proteins in skeletal muscle of group ES mice were significantly upregulated. There were no significant changes observed in the mice of group EG. Compared to the cells in group 0 mmol/L, the expression levels of p-InsRβ, p-IRS1, p-PI3K, and p-AKT proteins in cells of group 5 mmol/L were significantly downregulated. Compared to the cells in group C, the expression levels of p-InsRβ, p-IRS1, p-PI3K, and p-AKT proteins in the cells of group G were significantly downregulated. No significant changes were observed in the cells of group GK. ConclusionLong-term aerobic exercise can improve insulin sensitivity by lowering circulating levels of glutamate. This effect may be associated with the upregulation of the InsR/IRS1/AKT signaling pathway activity in skeletal muscle. Furthermore, glutamate can weaken the activity of the InsR/IRS1/PI3K/AKT signaling pathway in skeletal muscle, potentially by binding to NMDAR expressed in skeletal muscle.

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