1.Comparison and Behavioral Observation of Two Female Mice Models of Ulcerative Colitis
Juan WANG ; Jiahui XU ; Yunyuan TIAN ; Mengmeng ZHANG ; Min LI ; Siwang WANG ; Yao LI
Laboratory Animal and Comparative Medicine 2026;46(3):332-343
ObjectiveTo compare female C57BL/6J and BALB/c mice models of ulcerative colitis (UC) induced by dextran sulfate sodium salt (DSS), providing a reference for selecting female animal models in studies of innovative drugs for UC treatment. MethodsA total of 48 female mice aged 6–8 weeks, including 24 C57BL/6J and 24 BALB/c mice, were divided into four groups: control group, UC-3d group (2.5% DSS drinking for 3 days), UC-7d group (2.5% DSS drinking for 7 days), and UC-withdrawal group (2.5% DSS drinking for 7 days followed by 3 days of pure water replacement), with 6 mice in each group. Body weight, fecal occult blood, and stool characteristics were recorded daily, and disease activity index (DAI) scores were calculated. At the end of DSS induction, mice were gavaged with fluorescein isothiocyanate (FITC)-labeled dextran solution before tissue collection. Four hours later, under deep anesthesia induced by inhalation of 4% isoflurane, blood samples were collected from the retro-orbital venous plexus, and euthanasia was performed by cervical dislocation. The colon was then separated immediately, and its length from the anus to the ileocecal junction was measured. Colon tissues were fixed, embedded, and sectioned, and they were evaluated using hematoxylin-eosin (HE) staining and alcian blue-periodic acid-Schiff (AB-PAS) staining to comprehensively assess the degree of colonic inflammation. The spleen was also collected and weighed, and the spleen coefficient was calculated. Serum FITC fluorescence intensity and D-lactic acid concentration were measured to evaluate intestinal permeability and barrier injury. The grooming duration, the number of buried marbles, the time spent in the center of the open field, and the total distance traveled were measured to evaluate anxiety/depression-like behaviors in mice. ResultsFecal occult blood appeared in both C57BL/6J and BALB/c mice after 3 days of ad libitum access to DSS. Compared with the control group, there was no significant change in the weight loss rate of female BALB/c mice in the UC-7d and UC-withdrawal groups (P > 0.05), but the DAI score increased (P < 0.01). Conversely, both the weight loss rate and DAI score increased for female C57BL/6J mice in the UC-7d and UC-withdrawal groups (P < 0.01). In female C57BL/6J mice, both the UC-7d and UC-withdrawal groups had higher spleen coefficients than the control group (P < 0.05). Additionally, in these groups, colon length was significantly reduced (P < 0.01), FITC fluorescence intensity in serum was markedly increased (P < 0.01), obvious inflammatory reaction areas appeared in the colon, and the goblet cells and acidic mucus layer were damaged. In contrast, in female BALB/c mice, no significant differences were observed in colon length, serum FITC fluorescence intensity, or D-lactic acid concentration between the UC-7d and UC-withdrawal groups compared with the control group (P > 0.05). Only a few inflammatory cells and damaged goblet cells were observed in the colonic mucosal layer, and no other obvious pathological changes were detected. In addition, female C57BL/6J mice in the UC-7d group showed a significantly reduced total distance in the open field and fewer buried marbles (P < 0.05), indicating depression-like behavior, as well as prolonged grooming duration (P < 0.05), indicating anxiety-like behavior. ConclusionFemale BALB/c mice are not sensitive to 2.5% DSS and do not show typical colonic pathological changes of UC. In contrast, ad libitum access to 2.5% DSS for 7 days successfully induces typical UC pathological symptoms and colonic pathological changes in female C57BL/6J mice. These changes persist for 3 days after DSS withdrawal, and the mice also exhibit symptoms of anxiety/depression. The results suggest that this model can be used for research on the pathogenesis and therapeutic drugs of UC.
2.Mechanism of Jianfu mixture in the treatment of erectile dysfunction based on network pharmacology analysis, molecular docking and in vitro experimental validation
Yantao YANG ; Chao YU ; Zhihang ZHANG ; Yujiong PAN ; Xiaofeng HE ; Min XU
Journal of Pharmaceutical Practice and Service 2026;44(6):296-305
Objective To explore the molecular mechanism of Jianfu mixture in the treatment of erectile dysfunction (ED) by network pharmacology and molecular docking techniques, and validate its core targets and mechanisms through in vitro experiments. Methods The active components and corresponding molecular targets of Jianfu mixture were searched by searching TCMSP and Batman-TCM databases, and the disease targets of ED were searched by using GeneCards database. Find the intersection of drug ingredient target and disease target. The interaction between intersected targets was described and analyzed by String database, and the analysis results were visualized by Cytoscape software to determine the core target and the corresponding active components. GO functional enrichment analysis and KEGG pathway enrichment analysis were performed for intersection targets; the core target within the intersection were found through MCODE plug-in on Cytoscape software and molecular docking was performed with the corresponding active ingredients. An endothelial dysfunction model was established by transfecting HUVECs with si-eNOS. Intervene with different concentrations of the Jianfu mixture for the model cells for 24 h. QPCR was used to detect mRNA expression of core targets (MAPK1, MAPK3, JUN, ESR1, MAPK8); Western blot was used to analyze protein expression (eNOS, JUN, p-JUN, MAPK, p-MAPK) and phosphorylation levels. Results 144 effective active components and 168 active components target-disease targe intersection of Jianfu mixture were obtained. GO analysis revealed 200 5 biological processes, 151 molecular functions, and 63 cellular components. KEGG analysis yielded 181 pathways. 5 core targets including MAPK1, MAPK3, JUN, ESR1 and MAPK8 were screened out. The active components such as β-sitosterol, kaempferol, astapterocarpan had good binding affinity with the core target. In vitro experiments confirmed successful construction of the endothelial dysfunction model (eNOS expression significantly decreased after si-eNOS transfection). Jianfu mixture dose-dependently inhibited mRNA expression of MAPK1, MAPK3, JUN, ESR1, and MAPK8. Additionally, it reduced phosphorylation levels of JUN and MAPK, indicating inhibition of the JNK/c-Jun and ERK/MAPK signaling pathways to improve endothelial function. Conclusion Jianfu mixture treats ED by suppressing abnormal activation of multi-target signaling pathways (MAPK/JUN/ESR1), reducing endothelial apoptosis, and promoting NO synthesis. This mechanism aligns with the traditional Chinese medicine principle of “activating blood circulation, resolving stasis, tonifying Qi, and strengthening cardiovascular function.” The study provided molecular-level evidence for the therapeutic efficacy of Jianfu mixture in ED management.
3.Mechanism of Jianfu mixture in the treatment of erectile dysfunction based on network pharmacology analysis, molecular docking and in vitro experimental validation
Yantao YANG ; Chao YU ; Zhihang ZHANG ; Yujiong PAN ; Xiaofeng HE ; Min XU
Journal of Pharmaceutical Practice and Service 2026;44(6):296-305
Objective To explore the molecular mechanism of Jianfu mixture in the treatment of erectile dysfunction (ED) by network pharmacology and molecular docking techniques, and validate its core targets and mechanisms through in vitro experiments. Methods The active components and corresponding molecular targets of Jianfu mixture were searched by searching TCMSP and Batman-TCM databases, and the disease targets of ED were searched by using GeneCards database. Find the intersection of drug ingredient target and disease target. The interaction between intersected targets was described and analyzed by String database, and the analysis results were visualized by Cytoscape software to determine the core target and the corresponding active components. GO functional enrichment analysis and KEGG pathway enrichment analysis were performed for intersection targets; the core target within the intersection were found through MCODE plug-in on Cytoscape software and molecular docking was performed with the corresponding active ingredients. An endothelial dysfunction model was established by transfecting HUVECs with si-eNOS. Intervene with different concentrations of the Jianfu mixture for the model cells for 24 h. QPCR was used to detect mRNA expression of core targets (MAPK1, MAPK3, JUN, ESR1, MAPK8); Western blot was used to analyze protein expression (eNOS, JUN, p-JUN, MAPK, p-MAPK) and phosphorylation levels. Results 144 effective active components and 168 active components target-disease targe intersection of Jianfu mixture were obtained. GO analysis revealed 200 5 biological processes, 151 molecular functions, and 63 cellular components. KEGG analysis yielded 181 pathways. 5 core targets including MAPK1, MAPK3, JUN, ESR1 and MAPK8 were screened out. The active components such as β-sitosterol, kaempferol, astapterocarpan had good binding affinity with the core target. In vitro experiments confirmed successful construction of the endothelial dysfunction model (eNOS expression significantly decreased after si-eNOS transfection). Jianfu mixture dose-dependently inhibited mRNA expression of MAPK1, MAPK3, JUN, ESR1, and MAPK8. Additionally, it reduced phosphorylation levels of JUN and MAPK, indicating inhibition of the JNK/c-Jun and ERK/MAPK signaling pathways to improve endothelial function. Conclusion Jianfu mixture treats ED by suppressing abnormal activation of multi-target signaling pathways (MAPK/JUN/ESR1), reducing endothelial apoptosis, and promoting NO synthesis. This mechanism aligns with the traditional Chinese medicine principle of “activating blood circulation, resolving stasis, tonifying Qi, and strengthening cardiovascular function.” The study provided molecular-level evidence for the therapeutic efficacy of Jianfu mixture in ED management.
4.Value of liver and spleen stiffness measured by two-dimensional shear wave elastography in diagnosing the severity of portal hypertension
Min WANG ; Guanhua ZHANG ; Lijuan FENG ; Yuhong SUO ; Fuliang HE ; Xiangdong HU ; Min LI ; Yu WANG
Journal of Clinical Hepatology 2026;42(5):1075-1082
ObjectiveTo investigate the value of liver stiffness measurement (LSM) and spleen stiffness measurement (SSM) measured by two-dimensional shear wave elastography (2D-SWE) in the diagnosis of severe portal hypertension (SPH) and high-risk varices (HRV), and to provide a basis for noninvasive assessment of portal hypertension. MethodsA prospective study was conducted among 78 patients with cirrhotic portal hypertension who were treated in Liver Research Center of Beijing Friendship Hospital, Capital Medical University, from December 2019 to April 2023. According to hepatic venous pressure gradient (HVPG), the patients were divided into 6 mmHg≤HVPG<12 mmHg group, 12 mmHg≤HVPG<20 mmHg group, and HVPG ≥20 mmHg group. All patients underwent gastroscopy and 2D-SWE within 1 week after HVPG measurement, and SWE-LSM and SWE-SSM measured by 2D-SWE were recorded. A one-way analysis of variance or the Kruskal-Wallis H test was used for comparison of continuous data between multiple groups, and the chi-square test or the Fisher’s exact test was used for comparison of categorical data between groups. With HVPG and gastroscopy findings as the gold standard, the receiver operating characteristic (ROC) curve was plotted and the area under the ROC curve (AUC) was calculated to evaluate diagnostic performance, while the DeLong test was used for comparison of AUC. The Pearson or Spearman correlation analysis was used to investigate the correlation between variables, and the linear regression analysis and the Logistic regression analysis were used to investigate the influencing factors for HVPG and HRV. ResultsThe mean HVPG was 18.1±6.4 mmHg for the patients enrolled in this study, and HRV was observed in 62 patients (79.5%). Both SWE-LSM and SWE-SSM were significantly positively correlated with HVPG (r=0.413 and 0.633, both P<0.001), with an AUC of 0.812 and 0.902, respectively, in the diagnosis of HVPG≥12 mmHg and an AUC of 0.804 and 0.789, respectively, in the diagnosis of HVPG≥20 mmHg (all P>0.05). The multivariate linear regression analysis showed that SWE-SSM was an independent influencing factor for HVPG (β=0.17, P<0.001). In the diagnosis of HRV, only SWE-SSM showed a significant positive correlation with HRV (r=0.432, P<0.001), with a better diagnostic performance than SWE-LSM in terms of AUC (0.808 vs 0.642, Z=2.775, P=0.006). The multivariate Logistic regression analysis showed that platelet count was an independent influencing factor for HRV (odds ratio=0.97, P=0.014). ConclusionSWE-SSM is closely correlated with both HVPG and HRV, showing a good performance in the diagnosis of SPH and HRV, and therefore, it is expected to become an effective noninvasive tool for assessing portal hypertension.
5.From Bedside to Molecular Diagnosis-Multidisciplinary Treatment of a Rare Case of Autoinflammatory Disease Presenting with Skin Induration and Limb Weakness
Hanhui FU ; Wenjun WANG ; Yaping LIU ; Hui YOU ; Tao WANG ; Wen ZHANG ; Xuejun ZENG ; Liying CUI ; Huijuan ZHU ; Xiuli ZHAO ; Min SHEN ; Yicheng ZHU
JOURNAL OF RARE DISEASES 2026;5(2):207-213
This article reports a rare case of autoinflammatory disease presenting initially with skin induration and swelling after trauma as the initial manifestation, followed by progressive limb weakness. The patient was a middle-aged female who developed skin induration and swelling after trauma, which gradually progressed to limb weakness, dysarthria and bilateral facial paralysis, accompanied by livedo reticularis of the lower extremities, diffuse skin induration of the limbs, and beaded subcutaneous nodules in the right upper limb. The patient had a susceptibility to infection since childhood and a history of chronic livedo reticularis. Skin pathological examination revealed panniculitis. A comprehensive etiological screening for special infections and autoimmune diseases was completed with an unremarkable results, and whole-exome sequencing showed no abnormal findings. Following a multidisciplinary discussion combined with RNA sequencing results, the patient was diagnosed with an autoinflammatory disease, with a suspected type Ⅰ interferonopathy. Treatment with tofacitinib resulted in gradual improvement of clinical symptoms. This case highlights the importance of detailed medical history collection, systematic physical examination and multidisciplinary collaborative diagnosis and treatment, and underscores the pivotal role of molecular diagnosis in the confirmation of rare diseases. It can provide a reference for the clinical diagnosis and management of similar rare cases.
6.SIRT5 Potentiates Hepatocarcinogenesis by Modulating Protein Acylation in Mice
Yu ZHANG ; Feng-Rui REN ; Jia-Yun LI ; Xiang-Yu CHEN ; Zi-Yi WANG ; Qi SUN ; Jun-Cheng ZHAO ; Ye ZHANG ; Zhen HUANG ; Hao HU ; Tao-Tao WEI ; Min XIAO
Progress in Biochemistry and Biophysics 2026;53(6):1712-1722
ObjectiveHepatocellular carcinoma (HCC) represents 90% of all primary liver cancers. The main risk factors associated with HCC include viral hepatitis (B and/or C), alcohol abuse, and metabolic dysfunction-associated steatotic liver disease (MASLD), which progressively advance to liver fibrosis, cirrhosis, and ultimately evolve into HCC. Surgical resection represents the most effective treatment for HCC, while recent advances in immunotherapy, including immune checkpoint inhibitors and adoptive cell therapies, have provided improved treatment prospects for patients with unresectable HCC. However, the complex metabolic heterogeneity of HCC limits the therapeutic efficacy. Metabolic intermediates acyl-CoA not only provide energy and substrates for numerous biochemical reactions but also serve as donors for protein lysine acylation, a major class of post-translational modification (PTM). Therefore, a deeper understanding of the molecular mechanisms underlying protein lysine acylation and hepatocarcinogenesis is urgently needed. MethodsThe levels of protein lysine acylation and silence information regulator 5 (SIRT5) expression levels in clinical HCC samples were analyzed by Western blot. Quantitative malonylome and succinylome of HCC samples were analyzed by antibody-based affinity enrichment coupled with tandem mass spectrometry. The proliferation of HCC cells was analyzed with Cell Counting Kit-8 (CCK-8) assays, the apoptosis was quantified by Annexin V-FITC/propidium iodide (PI) staining coupled with flow cytometry, and the ability of cells to migrate was assayed by Transwell assays. The enzymatic activity of glutathione S-transferase Mu 1 (GSTM1) was quantified. Transgenic mice with hepatic overexpression of SIRT5 were constructed using CRISPR-Cas9, and primary hepatocarcinogenesis was induced by administration of diethylnitrosamine. ResultsWestern blot analysis indicated that the expression level of SIRT5 was elevated in clinical samples from HCC patients, and the levels of lysine malonylation, glutarylation, and succinylation were significantly reduced in HCC tissues. Knockout of SIRT5 in MHCC-97H and MHCC-97L hepatoma cells suppressed cell proliferation, and increased the percentage of apoptotic cells significantly. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the differentially malonylome and succinylome of HCC samples revealed significant enrichment in two major classes of biological processes: core energy metabolism (e.g., glycolysis/gluconeogenesis, tricarboxylic acid metabolic process, fatty acid beta oxidation) and detoxification and oxidative stress response (e.g., response to toxic substance, chemical carcinogenesis, reactive oxygen species (ROS)). SIRT5 removes malonylation from lysine residues in GSTM1 and restores its detoxification activity, which is crucial for the survival of hepatocytes under stressed conditions. More importantly, in vivo experiment indicated that hepatic-specific overexpression of SIRT5 in mice accelerated diethylnitrosamine-induced liver fibrosis and hepatocarcinogenesis, indicating the critical role of SIRT5 in HCC progression. ConclusionThis study highlights the previously unrecognized SIRT5-GSTM1 axis as a key regulator in hepatocarcinogenesis, and suggests a potential target for the treatment of patients with HCC.
7.Effects of androgens on cognitive function in castration male mice
Yaqi ZHANG ; Cancan HUI ; Fang REN ; Min XU ; Zilong JIANG ; Datong DENG
Acta Universitatis Medicinalis Anhui 2026;61(3):455-461
ObjectiveTo establish a castrated male mouse model and to preliminarily investigate the effects of testosterone replacement therapy (TRT) on behavior, serum indices, and histopathological changes in castrated mice, as well as to explore the role of androgens in cognitive function. MethodsForty 6-month-old male C57/BL6J mice were randomly divided into sham operation group, castration group, testosterone propionate (0.5,1.0 mg/kg) treated group, with 10 mice in each group. Following castration and subcutaneous administration of testosterone propionate at different doses (0.5 and 1.0 mg/kg) for TRT, learning and memory abilities were assessed using the Morris water maze (MWM) test and the passive avoidance test. Serum testosterone and serum brain-derived neurotrophic factor (BDNF) levels were measured by ELISA, and histopathological changes in the hippocampus were examined using hematoxylin-eosin (HE) staining. ResultsRoutine observations: there were no statistically significant differences in body weight among groups at any time point. MWM test: compared with castration group, sham operation group and testosterone propionate-treated groups (0.5, 1.0 mg/kg) showed significantly reduced escape latency on days 4 and 5 (P0.05), while the number of platform crossings and the time spent in the target quadrant significantly increased (P0.05). Passive avoidance test: the number of passive avoidance errors significantly decreased in sham operation group and testosterone propionate (1.0 mg/kg)-treated group (P0.05), and the passive avoidance latency was significantly prolonged in sham-operated group and testosterone propionate-treated groups (0.5, 1.0 mg/kg) (P0.05). Serum testosterone and serum BDNF assays: serum testosterone levels and serum BDNF concentrations significantly increased in sham operation group and testosterone propionate-treated groups (0.5, 1.0 mg/kg) (P0.01). HE staining: compared with sham operation group, neuronal density in all hippocampal subregions was slightly reduced in castration group; in the testosterone propionate (0.5 mg/kg)-treated group, neuronal arrangement in the CA1 and CA3 regions was improved and apoptotic cells were reduced compared with castration group; in testosterone propionate (1.0 mg/kg)-treated group, the pyramidal cell layer in the CA3 region was more compactly arranged, with fewer apoptotic cells than in castration group. ConclusionTRT improves learning and memory performance in castration male mice, potentially through modulation of hippocampal BDNF signaling pathways.
8.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.
9.Regulatory effect of histone lactylation modification in hepatic fibrosis
Weichu ZENG ; Xing LYU ; Fengfan LI ; Zhenni LIU ; Jungang LI ; Weilin ZHANG ; Peiting LIU ; Bingchu LI ; Ruohong CHEN ; Zhiyang CHEN ; Min HU
Journal of Clinical Hepatology 2026;42(3):704-710
Hepatic fibrosis is a reversible pathological process in various chronic liver diseases and is closely associated with the development and progression of severe liver diseases such as liver cirrhosis and hepatocellular carcinoma, and it has emerged as a significant global health challenge. In recent years, studies have shown that histone lactylation, a newly discovered epigenetic modification, actively participates in regulating the progression of hepatic fibrosis. This article systematically reviews the core regulatory effect of histone lactylation modification in the interaction between inflammatory microenvironment and hepatic fibrosis, in order to clarify the cascade regulatory mechanism of “inflammation-hepatic fibrosis” and provide new insights for early diagnosis, targeted intervention, and prevention of malignant transformation in hepatic fibrosis.
10.Study on the role and mechanism of SPP1+ macrophages in the formation of chronic renal allograft fibrosis
Zexin YANG ; Zeping GUI ; Junqi ZHANG ; Gang ZHANG ; Hao CHEN ; Li SUN ; Shuang FEI ; Min GU ; Zijie WANG
Organ Transplantation 2026;17(3):413-421
Objective To investigate the role and potential mechanism of secreted phosphoprotein 1 (SPP1)+ macrophages in the formation of chronic renal allograft fibrosis. Methods The expression features of SPP1+ macrophages in renal allografts of chronic allograft dysfunction (CAD) patients were analyzed based on single-cell transcriptome data of renal tissues from patients with CAD. Transcription factor VIPER analysis and DoRothEA transcription factor activity analysis were performed on the single-cell transcriptome data. Renal tissue samples were collected from kidney transplant recipients, including the CAD group (n=5) and the non-renal allograft fibrosis group (CTL group, n=5). A mouse model of chronic allograft rejection was established and divided into the allogeneic kidney transplantation group (CAD group, n=3) and the syngeneic kidney transplantation group (SYN group, n=3). Hematoxylin-eosin staining was used to detect renal tissue injury in mice, and Masson staining was used to detect renal tissue fibrosis. Immunofluorescence staining was performed to detect SPP1 expression in renal tissues of transplant recipients and mouse renal allografts. Bone marrow-derived macrophages (BMDMs) were extracted from mice and subjected to hypoxia stimulation. The expression of hypoxia-inducible factor (HIF)-1α and SPP1 was detected by Western blot, and SPP1 expression was detected by flow cytometry. BMDMs were transfected with HIF-1α overexpression plasmid and HIF-1α small interfering RNA (siRNA) followed by hypoxia intervention, and the expression of HIF-1α and SPP1 was detected by Western blot. Mouse aortic endothelial cells (MAECs) were co-cultured with the supernatant of BMDMs, and the expression of endothelial-mesenchymal transition (EndMT)-related markers was detected by Western blot and immunofluorescence. Results Single-cell transcriptome analysis showed that the proportion of SPP1+ macrophages in renal allograft tissues was significantly higher in the CAD group than in the CTL group (P<0.05). The renal injury score and the percentage of interstitial fibrotic area in the CAD group were significantly higher than those in the SYN group (both P<0.05). Immunofluorescence staining showed that the proportion of SPP1+ macrophages was increased in the CAD group compared with the CTL group, and also increased in the CAD group compared with the SYN group (both P<0.05). VIPER analysis and DoRothEA transcription factor activity analysis revealed activation of the hypoxia pathway and upregulated expression of transcription factors such as HIF-1α in SPP1+ macrophages. SPP1 expression was elevated in BMDMs under hypoxic conditions. Knockdown of HIF-1α inhibited hypoxia-induced SPP1 protein expression, whereas overexpression of HIF-1α upregulated SPP1 protein levels. After co-culture of hypoxia-induced BMDMs with MAECs, the expression levels of EndMT-related markers were increased. Conclusions SPP1+ macrophages differentiated under hypoxia are significantly infiltrated in the formation of chronic renal allograft fibrosis, and may promote renal allograft fibrosis by inducing EndMT in renal vascular endothelial cells.

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