Abstract： ObjectiveThe study aims to explore the effects and regulatory roles of glucose transporter 1 （GLUT1） on the proliferation， migration， adhesion， and angiogenesis of human umbilical vein endothelial cells （HUVECs） under ischemia-hypoxic conditions. MethodsIn vitro experiments were conducted to subject HUVECs to an ischemia-hypoxic-mimicking environment （1% O₂， 5% CO₂， 94% N₂）. The biological characteristics of HUVECs under normoxic and ischemia-hypoxic conditions were compared by assessing cell viability， proliferation capacity， and examining the expression changes of GLUT1， HIF-1α， and VEGFA proteins under ischemia-hypoxia using Western blot technology. Further， GLUT1 was overexpressed using plasmid transfection and the proliferation， migration， adhesion， and angiogenic capabilities of HUVECs were evaluated through scratch assays， cell adhesion assays， and tube formation assays. Mitochondrial morphological changes were observed by transmission electron microscopy，and oxygen consumption rate （OCR） was detected by Seahorse metabolic analyzer to evaluate mitochondrial function. ResultsCompared with normoxic conditions， the ischemia-hypoxic environment significantly inhibited the proliferation， cell viability， migration， and adhesion capabilities of HUVECs and impaired their angiogenic potential. The expression levels of GLUT1， HIF-1α and VEGFA proteins were also markedly reduced. However， when GLUT1 expression was upregulated， the migration， adhesion， and angiogenic capabilities of HUVECs were significantly improved， and the protein expression levels of HIF-1α， VEGFA and VEGFR were increased. Transmission electron microscopy revealed that ischemic-hypoxia leads to mitochondrial swelling and matrix damage， while GLUT1 overexpression significantly alleviates mitochondrial morphology abnormalities. OCR results suggest that GLUT1 overexpression may enhance oxidative phosphorylation of endothelial cells in ischemic-hypoxic environments to improve energy metabolism. These results suggest that GLUT1 may influence the function and angiogenic potential of HUVECs by regulating glucose metabolism and energy supply. ConclusionsThis study reveals the significant regulatory role of GLUT1 in the function of HUVECs under ischemia-hypoxic conditions， potentially through modulating cellular energy metabolism and signal transduction pathways， thereby affecting cell proliferation， migration， adhesion， and angiogenesis. These findings provide a new perspective on the role of GLUT1 in cardiovascular diseases and may offer potential targets for the development of new therapeutic strategies.

ObjectiveTo investigate the effect and mechanism of Sishenwan in restoring the intestinal barrier function in the rat model of diarrhea-predominant irritable bowel syndrome （IBS-D） due to spleen-kidney Yang deficiency based on intestinal flora and short-chain fatty acids. MethodsAfter the delivery of 10 SPF-grade pregnant rats， 4 male suckling rats were kept in each litter for the experiment. The male suckling rats were randomly allocated into blank， model， low-dose （3.51 g·kg^-1） Sishenwan， high-dose （7.02 g·kg^-1） Sishenwan， and Peifeikang （0.54 g·kg^-1） groups， with 8 rats in each group. The blank group was fed conventionally， and the other groups were subjected to mother-child separation and Sennae Folium gavage （1 g·mL^-1， 10 mL·kg^-1） for the modeling of IBS-D due to spleen-kidney Yang deficiency. After the modeling was completed， the rats in Sishenwan groups were administrated with the corresponding dose of Sishenwan decoction by gavage， and the Peifeikang group with bifidobacterium triple live powder+normal saline suspension. The blank and model groups were treated with an equal volume of normal saline by gavage. The general conditions and fecal characteristics of rats were observed. After 2 weeks of administration， the rats were anesthetized for sample collection. The pathological changes of the colon tissue in rats were observed by hematoxylin-eosin staining. Enzyme-linked immunosorbent assay was employed to measure the levels of transforming growth factor-beta （TGF-β）， interleukin-10 （IL-10）， and interleukin-22 （IL-22）. Immumohistochemical staining （IHC） was performed to detect the positive expression of zonula occludens-1 （ZO-1） and occludin in the colon tissue. Western blot was employed to determine the protein levels of ZO-1 and occludin in the colon tissue of rats， and 16S rRNA gene sequencing was performed for intestinal flora. Gas chromatography-mass spectrometry was employed to determine the content of short-chain fatty acids （SCFAs） in the cecum contents of rats. ResultsThe colon tissue in the blank group presented a clear structure， neat glands， and no inflammatory cell infiltration. In the model group， the colon tissue showcased a disorganized structure， irregular arrangement of glands， and inflammatory cell infiltration. Compared with the model group， the low-dose and high-dose Sishenwan groups and the Peifeikang group exhibited an intact colon tissue structure， regular arrangement of glands， and reduced inflammatory cell infiltration. Compared with the blank group， the modeling lowered the levels of TGF-β， IL-10， and IL-22 in the serum （P<0.01）， down-regulated the protein levels of ZO-1 and occludin in the colon tissue （P<0.01）， and decreased the content of acetic acid and propionic acid and increased the content of butyric acid in cecum contents （P<0.05）. Compared with the model group， low-dose and high-dose Sishenwan raised the levels of TGF-β， IL-10， and IL-22 in the serum （P<0.05， P<0.01）， and Peifeikang elevated the levels of TGF-β and IL-10 in the serum （P<0.01）. High-dose Sishenwan and Peifeikang up-regulated the protein levels of ZO-1 and occludin （P<0.05， P<0.01）， increased the content of acetic acid and propionic acid in cecum contents （P<0.05）， and decreased the content of butyric acid （P<0.05）. The 16S rRNA gene sequencing results showed that the intestinal flora structure of the model group changed compared with that of the blank group. Compared with the model group， Sishenwan and Peifeikang increased the relative abundance of Lachnospiraceae， Muribaculaceae， Akkermansiaceae， Ligilactobacillus， UBA3282， Akkermansia， and Corynebacterium while reducing the relative abundance of Oscillospiraceae， Desulfovibrionaceae， Lactobacillus， Romboutsia， and Desulfovibrio. They can restore the intestinal flora structure similar to that in the blank group. ConclusionSishenwan can alleviate diarrhea symptoms and colonic mucosal inflammation， increase the expression of tight junction proteins in the colonic mucosa， and strengthen the intestinal barrier in IBS-D rats with the syndrome of spleen-kidney Yang deficiency. The mechanism of action may be related to optimizing the structure and balance of intestinal flora and regulating the SCFAs， and the effect of high-dose Sishenwan is obvious.

ObjectiveTo investigate the effect and mechanism of Sishenwan in restoring the intestinal barrier function in the rat model of diarrhea-predominant irritable bowel syndrome （IBS-D） due to spleen-kidney Yang deficiency based on intestinal flora and short-chain fatty acids. MethodsAfter the delivery of 10 SPF-grade pregnant rats， 4 male suckling rats were kept in each litter for the experiment. The male suckling rats were randomly allocated into blank， model， low-dose （3.51 g·kg^-1） Sishenwan， high-dose （7.02 g·kg^-1） Sishenwan， and Peifeikang （0.54 g·kg^-1） groups， with 8 rats in each group. The blank group was fed conventionally， and the other groups were subjected to mother-child separation and Sennae Folium gavage （1 g·mL^-1， 10 mL·kg^-1） for the modeling of IBS-D due to spleen-kidney Yang deficiency. After the modeling was completed， the rats in Sishenwan groups were administrated with the corresponding dose of Sishenwan decoction by gavage， and the Peifeikang group with bifidobacterium triple live powder+normal saline suspension. The blank and model groups were treated with an equal volume of normal saline by gavage. The general conditions and fecal characteristics of rats were observed. After 2 weeks of administration， the rats were anesthetized for sample collection. The pathological changes of the colon tissue in rats were observed by hematoxylin-eosin staining. Enzyme-linked immunosorbent assay was employed to measure the levels of transforming growth factor-beta （TGF-β）， interleukin-10 （IL-10）， and interleukin-22 （IL-22）. Immumohistochemical staining （IHC） was performed to detect the positive expression of zonula occludens-1 （ZO-1） and occludin in the colon tissue. Western blot was employed to determine the protein levels of ZO-1 and occludin in the colon tissue of rats， and 16S rRNA gene sequencing was performed for intestinal flora. Gas chromatography-mass spectrometry was employed to determine the content of short-chain fatty acids （SCFAs） in the cecum contents of rats. ResultsThe colon tissue in the blank group presented a clear structure， neat glands， and no inflammatory cell infiltration. In the model group， the colon tissue showcased a disorganized structure， irregular arrangement of glands， and inflammatory cell infiltration. Compared with the model group， the low-dose and high-dose Sishenwan groups and the Peifeikang group exhibited an intact colon tissue structure， regular arrangement of glands， and reduced inflammatory cell infiltration. Compared with the blank group， the modeling lowered the levels of TGF-β， IL-10， and IL-22 in the serum （P<0.01）， down-regulated the protein levels of ZO-1 and occludin in the colon tissue （P<0.01）， and decreased the content of acetic acid and propionic acid and increased the content of butyric acid in cecum contents （P<0.05）. Compared with the model group， low-dose and high-dose Sishenwan raised the levels of TGF-β， IL-10， and IL-22 in the serum （P<0.05， P<0.01）， and Peifeikang elevated the levels of TGF-β and IL-10 in the serum （P<0.01）. High-dose Sishenwan and Peifeikang up-regulated the protein levels of ZO-1 and occludin （P<0.05， P<0.01）， increased the content of acetic acid and propionic acid in cecum contents （P<0.05）， and decreased the content of butyric acid （P<0.05）. The 16S rRNA gene sequencing results showed that the intestinal flora structure of the model group changed compared with that of the blank group. Compared with the model group， Sishenwan and Peifeikang increased the relative abundance of Lachnospiraceae， Muribaculaceae， Akkermansiaceae， Ligilactobacillus， UBA3282， Akkermansia， and Corynebacterium while reducing the relative abundance of Oscillospiraceae， Desulfovibrionaceae， Lactobacillus， Romboutsia， and Desulfovibrio. They can restore the intestinal flora structure similar to that in the blank group. ConclusionSishenwan can alleviate diarrhea symptoms and colonic mucosal inflammation， increase the expression of tight junction proteins in the colonic mucosa， and strengthen the intestinal barrier in IBS-D rats with the syndrome of spleen-kidney Yang deficiency. The mechanism of action may be related to optimizing the structure and balance of intestinal flora and regulating the SCFAs， and the effect of high-dose Sishenwan is obvious.

ObjectiveBased on literature data mining， this study explores the modeling elements of diarrhea-predominant irritable bowel syndrome （IBS-D） animal models in China and abroad， providing references and suggestions for improving modeling methods and evaluation indicators. MethodsRelevant literature on IBS-D animal experiments from 2014 to 2024 was retrieved through computer searches in databases such as China National Knowledge Infrastructure （CNKI）， Wanfang Data， VIP， Chinese Medical Journals Full-text Database， and PubMed. Information on experimental animal species， gender， body weight， modeling methods， modeling periods， intervention controls， modeling standards， and detection indicators was organized. Microsoft Excel 2021 software was used to establish a database and perform statistical analysis to examine the characteristics of IBS-D animal models. ResultsA total of 398 articles that met the inclusion criteria were reviewed. The IBS-D animal models were predominantly established using SD rats， Wistar rats， and C57BL/6 mice. Male animals were more commonly used， with rats typically aged 6-8 weeks and mice aged 4-6 weeks. In terms of interventions， piverium bromide was the main Western medicine， Tongxieyaofang was the primary Chinese medicine， and electroacupuncture was the primary acupuncture method. Among the modeling methods， the multi-factor combined composite modeling approach was the most common. Modeling periods were mainly concentrated between 1-14 days and 15-30 days. The success criteria for modeling were mainly evaluated based on the animal's general condition， fecal appearance， visceral sensitivity， gastrointestinal motility， behavior， and pathology. Detection indicators included apparent indexes， pathological markers， biochemical indicators， oxidative stress， brain-gut peptides， neurotransmitters， inflammatory factors， immune function， intestinal permeability， autophagy， apoptosis， proteins related to relevant signaling pathways， intestinal microbiota and its metabolites， etc. ConclusionThere are various methods for establishing IBS-D animal models， but no unified and universally accepted method has been established. The operation of the same modeling methods and the evaluation standards of the models vary across studies. Based on the results of data mining， the authors suggest that the multi-factor combined composite modeling approach most closely reflects the pathophysiological processes of IBS-D， better simulating the complex clinical symptoms of IBS-D patients， such as abdominal pain and diarrhea， and has a high degree of clinical relevance. This method is relatively recommended. While animal models in general align with Western medicine standards， models incorporating traditional Chinese medicine （TCM） syndromes are relatively few. Therefore， one of the future directions for research is to establish IBS-D animal models that meet the combined clinical disease and syndrome requirements of both Western and Chinese medicine.

[Objective] To investigate the factors influencing the detection of HLA-C expression by flow cytometry. [Methods] A total of 12 hematopoietic stem cell suspension samples from peripheral hematopoietic stem cell volunteer donors were randomly collected after CD34⁺ cell counting detection. The influence of detecting different number of nucleated cell (500 000, 50 000 and 5 000), sequential order of red blood cell lysis and antibody incubation, and the HLA-C antibody with varied remaining time from the expiration date on the detection results of HLA-C expression by flow cytometry were investigated, respectively. The significance of differences between different groups was analyzed through Student t test. [Results] There was no significant difference in the proportion of HLA-C positive cells and mean fluorescence intensity (MFI) among the three groups with different nucleated cell numbers detected (500 000, 50 000 and 5 000) (P>0.05). The sequential order of red blood cell lysis and antibody incubation had no influence on the proportion of HLA-C positive cells (P>0.05), but HLA-C MFI value was significantly lower when antibody incubation was performed after red blood cell lysis than that when antibody incubation was performed before red blood cell lysis (P<0.05). The proportion of HLA-C positive cells and MFI value detected by HLA-C antibody remaining 24 months from the expiration date were significantly higher than those detected by HLA-C antibody remaining only 5 months from the expiration date (P<0.05). [Conclusion] The present study has investigated the factors of influencing HLA-C expression level by flow cytometry, the results have important reference and application value for standardizing the experimental operation of HLA-C expression and improving the accuracy and comparability of detection results.

OBJECTIVE To provide reference for rational clinical use of immune checkpoint inhibitor （ICI）. METHODS Electronic medical record information of patients who received ICI treatment from January 1st 2020 to December 31st 2023 at a certain hospital was collected. Patients were divided into thyroid immune-related adverse event （irAE） group （subdivided into clinical hypothyroidism， clinical hyperthyroidism， subclinical hypothyroidism， and subclinical hyperthyroidism subgroups） and non- thyroid irAE group based on whether they experienced immune-induced thyroid irAE. Univariate and multivariate Logistic regression analyses were employed to analyze the influencing factors of ICI-related thyroid adverse events. RESULTS A total of 382 patients who received ICI treatment were included， with 137 cases in the thyroid irAE group （accounting for 35.9%） and 245 cases in the non-thyroid irAE group （accounting for 64.1%）. Multivariate Logistic regression analysis， following univariate screening， revealed that ICI combined with radiotherapy was positively associated with the occurrence of thyroid irAE [odds ratio （OR）＝2.157， 95% confidence interval （CI） （1.144， 4.066）， P＜0.05]， while lung squamous cell carcinoma was negatively associated with the occurrence of thyroid irAE [OR＝0.600， 95%CI （0.369， 0.975）， P＜0.05]. Among various thyroid irAE， nasopharyngeal malignancy was positively associated with the occurrence of immune-related clinical hyperthyroidism [OR＝4.678， 95%CI （1.149， 19.042）， P＜0.05]； ICI combined with radiotherapy [OR＝2.622， 95%CI （1.227， 5.603）， P＜0.05] and lung adenocarcinoma [OR＝2.013， 95%CI （1.078， 3.759）， P＜0.05] were positively associated with the occurrence of immune-related subclinical hyperthyroidism. Age was negatively associated with the occurrence of immune-related clinical hypothyroidism [OR＝0.944， 95%CI （0.896， 0.995）， P＜0.05]； age [OR＝0.963， 95%CI （0.932， 0.994）， P＜0.05] and ICI combined with chemotherapy [OR＝0.332， 95%CI （0.137， 0.802）， P＜0.05] were negatively associated with the occurrence of immune-related subclinical hypothyroidism. CONCLUSIONS Among patients receiving ICI treatment， younger patients are more prone to thyroid irAE. Patients receiving ICI combined with chemotherapy are less likely to experience subclinical hypothyroidism， while ICI combined with radiotherapy significantly increases the risk of thyroid adverse events.

ObjectiveThis study aims to develop a prediction model for the compatibility of Chinese medicinal pairs based on Graph Convolutional Networks （GCN）， named HC-GCN. The model integrates the properties of herbs with modern pharmacological mechanisms to predict pairs with specific therapeutic effects. It serves as a demonstration by applying the model to predict and validate the efficacy of blood-activating herb pairs. MethodsThe training dataset for herb pair prediction was constructed by systematically collecting commonly used herb pairs along with their characteristic data， including Qi， flavor， meridian tropism， and target genes. Integrating traditional characteristics of herb with modern bioinformatics， we developed an efficacy-oriented herb pair compatibility prediction model （HC-GCN） using graph convolutional networks （GCN）. This model leverages machine learning to capture the complex relationships in herb pair compatibility， weighted by efficacy features. The performance of the HC-GCN model was evaluated using accuracy （ACC）， recall， precision， F1 score （F1）， and area under the ROC curve （AUC）. Its predictive effectiveness was then compared to five other machine learning models： eXtreme Gradient Boosting （XGBoost）， logistic regression （LR）， Naive Bayes， K-nearest neighbor （KNN）， and support vector machine （SVM）. ResultsUsing herb pairs with blood-activating effects as a demonstration， a prediction model was constructed based on a foundational dataset of 46 blood-activating herb pairs， incorporating their Qi， flavor， meridian tropism， and target gene characteristics. The HC-GCN model outperforms other commonly used machine learning models in key performance metrics， including ACC， recall， precision， F1 score， and AUC. Through the predictive analysis of the HC-GCN model， 60 herb pairs with blood-activating effects were successfully identified. Among of these potential herb pairs， 44 include at least one herb with blood-activating effects. ConclusionIn this study， we established an efficacy-oriented compatibility prediction model for herb pairs based on GCN by integrating the unique characteristics of traditional herbs with modern pharmacological mechanisms. This model demonstrated high predictive performance， offering a novel approach for the intelligent screening and optimization of traditional Chinese medicine prescriptions， as well as their clinical applications.

Background Arsenic is an environmentally harmful substance that causes hepatic insulin resistance and liver damage, increasing the risk of type 2 diabetes mellitus. Objective To explore whether the insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) is involved in insulin resistance in HepG2 cells after arsenic exposure through the peroxisome-proliferator-activated receptor γ (PPAR-γ) / glucose transporter 4 (GLUT4) pathway. Methods Cell viability was determined using cell counting kit 8 (CCK8) and an appropriate NaAsO₂ infection dose was determined. A cellular arsenic exposure model of HepG2 cells was established by four concentrations of NaAsO₂ solution for 24 h (the experiment was divided into four groups: 0, 2, 4, and 8 μmol·L⁻¹); HepG2 cells were firstly treated with pcDNA3.1-IGF2BP2 and pcDNA3.1-NC respectively for 6 h, then with 8 μmol·L⁻¹ NaAsO₂ for 24 h to establish a IGF2BP2 overexpression cell model (the experiment was divided into 4 groups: control, NaAsO₂, NaAsO₂+pcDNA3.1-IGF2BP2, and NaAsO₂+pcDNA3.1-NC); finally the cells were subject to 100 nmol·L⁻¹ insulin stimulation for 30 min. Glycogen and glucose in HepG2 cells were determined by glycogen and glucose assay kits; mRNA expression levels of IGF2BP2 were measured by quantitative real-time PCR; protein expression levels of IGF2BP2, PPAR-γ, and GLUT4 in HepG2 were detected by Western blot (WB); and the binding of IGF2BP2 to PPAR-γ and PPAR-γ to GLUT4 was verified by co-immunoprecipitation (CO-IP) experiment. Results The results of CCK8 experiment showed a dose-effect relationship between NaAsO₂ concentration and cell viability. When the concentration of NaAsO₂ was ≥4 μmol·L⁻¹ , the cell viabilities were lower than that of the control group (P <0.05). With the increasing dose of NaAsO₂ infection, reduced glucose consumption and glycogen levels in HepG2 cells were found in the 2, 4, and 8 μmol·L⁻¹ NaAsO₂ treatment groups compared to the control group (P <0.05). The difference between the mRNA expression level of IGF2BP2 in the HepG2 cells treated with 4 or 8 μmol L⁻¹ NaAsO₂ and the control group was significant (P <0.05). In the IGF2BP2 overexpression cell model, compared with the control group, glucose consumption and glycogen levels were lowered in the NaAsO₂ group (P <0.05), the mRNA expression level of IGF2BP2 and the protein expression levels of IGF2BP2, PPAR-γ, and GLUT4 in the cell membrane were all decreased (P <0.05). Compared with the NaAsO₂ group, the glucose consumption and glycogen levels were increased in the NaAsO₂+pcDNA3.1-IGF2BP2 group (P <0.05), and the mRNA expression level of IGF2BP2 and the protein expression levels of IGF2BP2, PPAR-γ, and GLUT4 in the cell membrane were all increased (P <0.05). The results of CO-IP experiments showed that IGF2BP2 interacted with PPAR-γ as well as PPAR-γ with GLUT4 protein. Conclusion IGF2BP2 is involved in arsenic exposure-induced insulin resistance in HepG2 cells by acting on the PPAR-γ/GLUT4 pathway.

Background Salidroside (SAL) has a protective effect on multiple organ systems. Exposure to fine particulate matter (PM_2.5) in the atmosphere may lead to disruptions in gut microbiota and impact intestinal health. The regulatory effect of SAL on the gut microbiota of mice exposed to PM_2.5 requires further investigation. Objective To evaluate gut microbiota disruption in mice after being exposed to PM_2.5 and the potential effect of SAL. Methods Forty male C57BL/6 mice, aged 6 to 8 weeks, were randomly divided into four groups: a control group, an SAL group, a PM_2.5 group, and an SAL+PM_2.5 group, each containing 10 mice. In the SAL group and the SAL+PM_2.5 group, the mice were administered SAL (60 mg·kg⁻¹) by gavage, while in the control group and the PM_2.5 group, sterile saline (10 mL·kg⁻¹) was administered by gavage. In the PM_2.5 group and the SAL+PM_2.5 group, PM_2.5 suspension (8 mg·kg⁻¹) was intratracheally instilled, and in the control group and SAL group, sterile saline (1.5 mL·kg⁻¹) was intratracheally administered. Each experiment cycle spanned 2 d, with a total of 10 cycles conducted over 20 d. Histopathological changes in the ileum tissue of the mice were observed after HE staining. Colon contents were collected for gut microbiota sequencing and short-chain fatty acids (SCFAs) measurements. Results The PM_2.5 group showed infiltration of inflammatory cells in the ileum tissue, while the SAL+PM_2.5 group exhibited only a small amount of inflammatory cell infiltration. Compared to the control group, the PM_2.5 group showed decreased Shannon index (P<0.05) and increased Simpson index (P<0.05), indicating that the diversity of gut microbiota in this group was decreased; the SAL+PM_2.5 group showed increased Shannon index compared to the PM_2.5 group (P<0.05) and decreased Simpson index (P<0.05), indicating that the diversity of gut microbiota in mice intervened with SAL was increased. The principal coordinates analysis (PCoA) revealed a significant separation between the PM_2.5 group and the control group, while the separation trend was less evident among the control group, the SAL group, and the SAL+PM_2.5 group. The unweighted pair-group method with arithmetic means (UPGMA) clustering tree results showed that the control group and the SAL group clustered together first, followed by clustering with the SAL+PM_2.5 group, and finally, the three groups clustered with the PM_2.5 group. The PCoA and UPGMA clustering results indicated that the uniformity and similarity of the microbiota in the PM_2.5 group were significantly decreased. Compared to the control group, the PM_2.5 group showed decreased abundance of phylum Bacteroidetes and Candidatus_Saccharimonas (P<0.05) and increased abundance of phylum Proteobacteria, genus Escherichia, genus Bacteroides, genus Prevotella, genus Enterococcus, and genus Proteus (P<0.05). Compared to the PM_2.5 group, the SAL+PM_2.5 group showed decreased abundance of phylum Proteobacteria, phylum Actinobacteria, genus Prevotella, and genus Proteus (P<0.05), and increased abundance of Candidatus_Saccharimonas (P<0.05). The PM_2.5 group showed reduced levels of propionic acid, valeric acid, and hexanoic acid compared to the control group (P<0.05), while the SAL+PM_2.5 group showed increased levels of propionic acid, isobutyric acid, butyric acid, valeric acid, and hexanoic acid compared to the PM_2.5 group (P<0.05). Conclusion Exposure to PM_2.5 can cause pathological alterations, microbial dysbiosis, and disturbing production of SCFAs in intestinal tissue in mice. However, SAL can provide a certain degree of protective effect against these changes.

Background Atmospheric fine particulate matter (PM_2.5) can disrupt the metabolic homeostasis of the liver and accelerate the progression of liver diseases, but there are few studies on the effects of sub-chronic PM_2.5 exposure on the liver metabolome. Objectives To investigate the effects of sub-chronic exposure to concentrated PM_2.5 on hepatic metabolomics in mice by liquid chromatography-mass spectrometry (LC-MS), and to identify potentially affected metabolites and metabolic pathways. Methods Twelve male C57BL/6J (6 weeks old) mice were randomly divided into two groups: a concentrated PM_2.5 exposure group and a clean air exposure group. The mice were exposed to concentrated PM_2.5 using the "Shanghai Meteorological and Environmental Animal Exposure System" at Fudan University. The exposure duration was 8 h per day, 6 d per week, for a total of 8 weeks. The mice's liver tissues were collected 24 h after the completion of exposure. LC-MS was performed to assess changes in the hepatic metabolome. Orthogonal partial least squares discriminant analysis and t-test were employed to identify differentially regulated metabolites between the two groups under the conditions of variable important in projection (VIP)≥1.0 and P<0.05. Metabolic pathway enrichment analysis was performed using MetaboAnalyst 5.0 software and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Results A total of 297 differentially regulated metabolites were identified between the concentrated PM_2.5 exposure group and the clean air group. Among these metabolites, 142 were upregulated and 155 were downregulated. A total of 38 metabolic pathways were altered, with 7 pathways showing significant perturbation (P<0.05). These pathways involved amino acid metabolism, glucose metabolism, nucleotide metabolism, as well as cofactor and vitamin metabolism. The 7 significant metabolic pathways were pantothenic acid and coenzyme A biosynthesis; purine metabolism; amino sugar and nucleotide sugar metabolism; arginine biosynthesis; alanine, aspartate and glutamate metabolism; aminoacyl-tRNA biosynthesis; and fructose and mannose metabolism. Conclusion The results from metabolomics analysis suggest that sub-chronic exposure to PM_2.5 may disrupt hepatic energy metabolism and induce oxidative stress damage. Aspartic acid, succinic acid, ornithine, fumaric acid, as well as purine and xanthine derivatives, were identified as potential early biomarkers of hepatic response to sub-chronic PM_2.5 exposure.