1.High-throughput single-microbe RNA sequencing reveals adaptive state heterogeneity and host-phage activity associations in human gut microbiome.
Yifei SHEN ; Qinghong QIAN ; Liguo DING ; Wenxin QU ; Tianyu ZHANG ; Mengdi SONG ; Yingjuan HUANG ; Mengting WANG ; Ziye XU ; Jiaye CHEN ; Ling DONG ; Hongyu CHEN ; Enhui SHEN ; Shufa ZHENG ; Yu CHEN ; Jiong LIU ; Longjiang FAN ; Yongcheng WANG
Protein & Cell 2025;16(3):211-226
Microbial communities such as those residing in the human gut are highly diverse and complex, and many with important implications for health and diseases. The effects and functions of these microbial communities are determined not only by their species compositions and diversities but also by the dynamic intra- and inter-cellular states at the transcriptional level. Powerful and scalable technologies capable of acquiring single-microbe-resolution RNA sequencing information in order to achieve a comprehensive understanding of complex microbial communities together with their hosts are therefore utterly needed. Here we report the development and utilization of a droplet-based smRNA-seq (single-microbe RNA sequencing) method capable of identifying large species varieties in human samples, which we name smRandom-seq2. Together with a triple-module computational pipeline designed for the bacteria and bacteriophage sequencing data by smRandom-seq2 in four human gut samples, we established a single-cell level bacterial transcriptional landscape of human gut microbiome, which included 29,742 single microbes and 329 unique species. Distinct adaptive response states among species in Prevotella and Roseburia genera and intrinsic adaptive strategy heterogeneity in Phascolarctobacterium succinatutens were uncovered. Additionally, we identified hundreds of novel host-phage transcriptional activity associations in the human gut microbiome. Our results indicated that smRandom-seq2 is a high-throughput and high-resolution smRNA-seq technique that is highly adaptable to complex microbial communities in real-world situations and promises new perspectives in the understanding of human microbiomes.
Humans
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Gastrointestinal Microbiome/genetics*
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Bacteriophages/physiology*
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High-Throughput Nucleotide Sequencing
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Sequence Analysis, RNA/methods*
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Bacteria/virology*
2.The influence of knocking down the expression of low-density lipoprotein receptor associated proteins on the vascular abnormalities in hepatocellular carcinoma and its mechanisms
Qiang WU ; Linlin ZHAN ; Yu WANG ; Yuchao HE ; Lu CHEN ; Ziye CHEN ; Guangtao LI ; Dongming LIU ; Xu BAO ; Xiaomeng LIU ; Hua GUO ; Tianqiang SONG
Chinese Journal of Oncology 2024;46(5):399-408
Objectives:To investigate the effect of the expression of low-density lipoprotein receptor associated protein (LDLR) on the vascular abnormalities in hepatocellular carcinoma (HCC) and its mechanisms.Methods:Based on the information of Oncomine Cancer GeneChip database, we analyzed the correlation between the expression level of LDLR and the expression level of carcinoembryonic antigen (CEA) and CD31 in hepatocellular carcinoma tissues. Lentiviral transfection of short hairpin RNA target genes was used to construct LDLR-knockdown MHCC-97H and HLE hepatocellular carcinoma cells. The differential genes and their expression level changes in LDLR-knockdown hepatocellular carcinoma cells were detected by transcriptome sequencing, real-time fluorescence quantitative polymerase chain reaction, and protein immunoblotting. The gene-related signaling pathways that involve LDLR were clarified by enrichment analysis. The effect of LDLR on CEA was assessed by the detection of CEA content in conditioned medium of hepatocellular carcinoma cells. Angiogenesis assay was used to detect the effect of LDLR on the angiogenic capacity of human umbilical vein endothelial cells, as well as the role of CEA in the regulation of angiogenesis by LDLR. Immunohistochemical staining was used to detect the expression levels of LDLR in 176 hepatocellular carcinoma tissues, and CEA and CD31 in 146 hepatocellular carcinoma tissues, and analyze the correlations between the expression levels of LDLR, CEA, and CD31 in the tissues, serum CEA, and alanine transaminase (ALT).Results:Oncomine database analysis showed that the expressions of LDLR and CEA in the tissues of hepatocellular carcinoma patients with portal vein metastasis were negatively correlated ( r=-0.64, P=0.001), whereas the expressions of CEA and CD31 in these tissues were positively correlated ( r=0.46, P=0.010). The transcriptome sequencing results showed that there were a total of 1 032 differentially expressed genes in the LDLR-knockdown group and the control group of MHCC-97H cells, of which 517 genes were up-regulated and 515 genes were down-regulated. The transcript expression level of CEACAM5 was significantly up-regulated in the cells of the LDLR-knockdown group. The Gene Ontology (GO) function enrichment analysis showed that the differential genes were most obviously enriched in the angiogenesis function. The Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis showed that the relevant pathways involved mainly included the cellular adhesion patch, the extracellular matrix receptor interactions, and the interactions with the extracellular matrix receptors. The CEA content in the conditioned medium of the LDLR-knockdown group was 43.75±8.43, which was higher than that of the control group (1.15±0.14, P<0.001). The results of angiogenesis experiments showed that at 5 h, the number of main junctions, the number of main segments, and the total area of the lattice formed by HUVEC cells cultured with the conditioned medium of MHCC-97H cells in the LDLR-knockdown group were 295.3±26.4, 552.5±63.8, and 2 239 781.0±13 8211.9 square pixels, which were higher than those of the control group (113.3±23.5, 194.8±36.5, and 660 621.0±280 328.3 square pixels, respectively, all P<0.01).The number of vascular major junctions, the number of major segments, and the total area of the lattice formed by HUVEC cells cultured in conditioned medium with HLE cells in the LDLR-knockdown group were 245.3±42.4, 257.5±20.4, and 2 535 754.5±249 094.2 square pixels, respectively, which were all higher than those of the control group (113.3±23.5, 114.3±12.2, and 1 565 456.5±219 259.7 square pixels, respectively, all P<0.01). In the conditioned medium for the control group of MHCC-97H cells,the number of main junctions, the number of main segments, and the total area of the lattice formed by the addition of CEA to cultured HUVEC cells were 178.9±12.0, 286.9±12.3, and 1 966 990.0±126 249.5 spixels, which were higher than those in the control group (119.7±22.1, 202.7±33.7, and 1 421 191.0±189 837.8 square pixels, respectively). The expression of LDLR in hepatocellular carcinoma tissues was not correlated with the expression of CEA, but was negatively correlated with the expression of CD31 ( r=-0.167, P=0.044), the level of serum CEA ( r=-0.061, P=0.032), and the level of serum ALT (r=-0.147, P=0.05). The expression of CEA in hepatocellular carcinoma tissues was positively correlated with the expression of CD31 ( r=0.192, P=0.020). The level of serum CEA was positively correlated with the level of serum ALT ( r=0.164, P=0.029). Conclusion:Knocking down LDLR can promote vascular abnormalities in HCC by releasing CEA.
3.The influence of knocking down the expression of low-density lipoprotein receptor associated proteins on the vascular abnormalities in hepatocellular carcinoma and its mechanisms
Qiang WU ; Linlin ZHAN ; Yu WANG ; Yuchao HE ; Lu CHEN ; Ziye CHEN ; Guangtao LI ; Dongming LIU ; Xu BAO ; Xiaomeng LIU ; Hua GUO ; Tianqiang SONG
Chinese Journal of Oncology 2024;46(5):399-408
Objectives:To investigate the effect of the expression of low-density lipoprotein receptor associated protein (LDLR) on the vascular abnormalities in hepatocellular carcinoma (HCC) and its mechanisms.Methods:Based on the information of Oncomine Cancer GeneChip database, we analyzed the correlation between the expression level of LDLR and the expression level of carcinoembryonic antigen (CEA) and CD31 in hepatocellular carcinoma tissues. Lentiviral transfection of short hairpin RNA target genes was used to construct LDLR-knockdown MHCC-97H and HLE hepatocellular carcinoma cells. The differential genes and their expression level changes in LDLR-knockdown hepatocellular carcinoma cells were detected by transcriptome sequencing, real-time fluorescence quantitative polymerase chain reaction, and protein immunoblotting. The gene-related signaling pathways that involve LDLR were clarified by enrichment analysis. The effect of LDLR on CEA was assessed by the detection of CEA content in conditioned medium of hepatocellular carcinoma cells. Angiogenesis assay was used to detect the effect of LDLR on the angiogenic capacity of human umbilical vein endothelial cells, as well as the role of CEA in the regulation of angiogenesis by LDLR. Immunohistochemical staining was used to detect the expression levels of LDLR in 176 hepatocellular carcinoma tissues, and CEA and CD31 in 146 hepatocellular carcinoma tissues, and analyze the correlations between the expression levels of LDLR, CEA, and CD31 in the tissues, serum CEA, and alanine transaminase (ALT).Results:Oncomine database analysis showed that the expressions of LDLR and CEA in the tissues of hepatocellular carcinoma patients with portal vein metastasis were negatively correlated ( r=-0.64, P=0.001), whereas the expressions of CEA and CD31 in these tissues were positively correlated ( r=0.46, P=0.010). The transcriptome sequencing results showed that there were a total of 1 032 differentially expressed genes in the LDLR-knockdown group and the control group of MHCC-97H cells, of which 517 genes were up-regulated and 515 genes were down-regulated. The transcript expression level of CEACAM5 was significantly up-regulated in the cells of the LDLR-knockdown group. The Gene Ontology (GO) function enrichment analysis showed that the differential genes were most obviously enriched in the angiogenesis function. The Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis showed that the relevant pathways involved mainly included the cellular adhesion patch, the extracellular matrix receptor interactions, and the interactions with the extracellular matrix receptors. The CEA content in the conditioned medium of the LDLR-knockdown group was 43.75±8.43, which was higher than that of the control group (1.15±0.14, P<0.001). The results of angiogenesis experiments showed that at 5 h, the number of main junctions, the number of main segments, and the total area of the lattice formed by HUVEC cells cultured with the conditioned medium of MHCC-97H cells in the LDLR-knockdown group were 295.3±26.4, 552.5±63.8, and 2 239 781.0±13 8211.9 square pixels, which were higher than those of the control group (113.3±23.5, 194.8±36.5, and 660 621.0±280 328.3 square pixels, respectively, all P<0.01).The number of vascular major junctions, the number of major segments, and the total area of the lattice formed by HUVEC cells cultured in conditioned medium with HLE cells in the LDLR-knockdown group were 245.3±42.4, 257.5±20.4, and 2 535 754.5±249 094.2 square pixels, respectively, which were all higher than those of the control group (113.3±23.5, 114.3±12.2, and 1 565 456.5±219 259.7 square pixels, respectively, all P<0.01). In the conditioned medium for the control group of MHCC-97H cells,the number of main junctions, the number of main segments, and the total area of the lattice formed by the addition of CEA to cultured HUVEC cells were 178.9±12.0, 286.9±12.3, and 1 966 990.0±126 249.5 spixels, which were higher than those in the control group (119.7±22.1, 202.7±33.7, and 1 421 191.0±189 837.8 square pixels, respectively). The expression of LDLR in hepatocellular carcinoma tissues was not correlated with the expression of CEA, but was negatively correlated with the expression of CD31 ( r=-0.167, P=0.044), the level of serum CEA ( r=-0.061, P=0.032), and the level of serum ALT (r=-0.147, P=0.05). The expression of CEA in hepatocellular carcinoma tissues was positively correlated with the expression of CD31 ( r=0.192, P=0.020). The level of serum CEA was positively correlated with the level of serum ALT ( r=0.164, P=0.029). Conclusion:Knocking down LDLR can promote vascular abnormalities in HCC by releasing CEA.
4.Prediction of Screw Loosening After Dynamic Pedicle Screw Fixation With Lumbar Polyetheretherketone Rods Using Magnetic Resonance Imaging-Based Vertebral Bone Quality Score
Guozheng JIANG ; Luchun XU ; Yukun MA ; Jianbin GUAN ; Yongdong YANG ; Wenqing ZHONG ; Wenhao LI ; Shibo ZHOU ; JiaWei SONG ; Ningning FENG ; Ziye QIU ; Zeyu LI ; YiShu ZHOU ; Letian MENG ; Yi QU ; Xing YU
Neurospine 2024;21(2):712-720
Objective:
To investigate the correlation between magnetic resonance imaging-based vertebral bone quality (VBQ) score and screw loosening after dynamic pedicle screw fixation with polyetheretherketone (PEEK) rods, and evaluate its predictive value.
Methods:
A retrospective analysis was conducted on the patients who underwent dynamic pedicle screw fixation with PEEK rods from March 2017 to June 2022. Data on age, sex, body mass index, hypertension, diabetes, hyperlipidemia history, long-term smoking, alcohol consumption, VBQ score, L1–4 average Hounsfield unit (HU) value, surgical fixation length, and the lowest instrumented vertebra were collected. Logistic regression analysis was employed to assess the relationship between VBQ score and pedicle screw loosening (PSL).
Results:
A total of 24 patients experienced PSL after surgery (20.5%). PSL group and non-PSL group showed statistical differences in age, number of fixed segments, fixation to the sacrum, L1–4 average HU value, and VBQ score (p < 0.05). The VBQ score in the PSL group was higher than that in the non-PSL group (3.56 ± 0.45 vs. 2.77 ± 0.31, p < 0.001). In logistic regression analysis, VBQ score (odds ratio, 3.425; 95% confidence interval, 1.552–8.279) were identified as independent risk factors for screw loosening. The area under the receiver operating characteristic curve for VBQ score predicting PSL was 0.819 (p < 0.05), with the optimal threshold of 3.15 (sensitivity, 83.1%; specificity, 80.5%).
Conclusion
The VBQ score can independently predict postoperative screw loosening in patients undergoing lumbar dynamic pedicle screw fixation with PEEK rods, and its predictive value is comparable to HU value.
5.Prediction of Screw Loosening After Dynamic Pedicle Screw Fixation With Lumbar Polyetheretherketone Rods Using Magnetic Resonance Imaging-Based Vertebral Bone Quality Score
Guozheng JIANG ; Luchun XU ; Yukun MA ; Jianbin GUAN ; Yongdong YANG ; Wenqing ZHONG ; Wenhao LI ; Shibo ZHOU ; JiaWei SONG ; Ningning FENG ; Ziye QIU ; Zeyu LI ; YiShu ZHOU ; Letian MENG ; Yi QU ; Xing YU
Neurospine 2024;21(2):712-720
Objective:
To investigate the correlation between magnetic resonance imaging-based vertebral bone quality (VBQ) score and screw loosening after dynamic pedicle screw fixation with polyetheretherketone (PEEK) rods, and evaluate its predictive value.
Methods:
A retrospective analysis was conducted on the patients who underwent dynamic pedicle screw fixation with PEEK rods from March 2017 to June 2022. Data on age, sex, body mass index, hypertension, diabetes, hyperlipidemia history, long-term smoking, alcohol consumption, VBQ score, L1–4 average Hounsfield unit (HU) value, surgical fixation length, and the lowest instrumented vertebra were collected. Logistic regression analysis was employed to assess the relationship between VBQ score and pedicle screw loosening (PSL).
Results:
A total of 24 patients experienced PSL after surgery (20.5%). PSL group and non-PSL group showed statistical differences in age, number of fixed segments, fixation to the sacrum, L1–4 average HU value, and VBQ score (p < 0.05). The VBQ score in the PSL group was higher than that in the non-PSL group (3.56 ± 0.45 vs. 2.77 ± 0.31, p < 0.001). In logistic regression analysis, VBQ score (odds ratio, 3.425; 95% confidence interval, 1.552–8.279) were identified as independent risk factors for screw loosening. The area under the receiver operating characteristic curve for VBQ score predicting PSL was 0.819 (p < 0.05), with the optimal threshold of 3.15 (sensitivity, 83.1%; specificity, 80.5%).
Conclusion
The VBQ score can independently predict postoperative screw loosening in patients undergoing lumbar dynamic pedicle screw fixation with PEEK rods, and its predictive value is comparable to HU value.
6.Prediction of Screw Loosening After Dynamic Pedicle Screw Fixation With Lumbar Polyetheretherketone Rods Using Magnetic Resonance Imaging-Based Vertebral Bone Quality Score
Guozheng JIANG ; Luchun XU ; Yukun MA ; Jianbin GUAN ; Yongdong YANG ; Wenqing ZHONG ; Wenhao LI ; Shibo ZHOU ; JiaWei SONG ; Ningning FENG ; Ziye QIU ; Zeyu LI ; YiShu ZHOU ; Letian MENG ; Yi QU ; Xing YU
Neurospine 2024;21(2):712-720
Objective:
To investigate the correlation between magnetic resonance imaging-based vertebral bone quality (VBQ) score and screw loosening after dynamic pedicle screw fixation with polyetheretherketone (PEEK) rods, and evaluate its predictive value.
Methods:
A retrospective analysis was conducted on the patients who underwent dynamic pedicle screw fixation with PEEK rods from March 2017 to June 2022. Data on age, sex, body mass index, hypertension, diabetes, hyperlipidemia history, long-term smoking, alcohol consumption, VBQ score, L1–4 average Hounsfield unit (HU) value, surgical fixation length, and the lowest instrumented vertebra were collected. Logistic regression analysis was employed to assess the relationship between VBQ score and pedicle screw loosening (PSL).
Results:
A total of 24 patients experienced PSL after surgery (20.5%). PSL group and non-PSL group showed statistical differences in age, number of fixed segments, fixation to the sacrum, L1–4 average HU value, and VBQ score (p < 0.05). The VBQ score in the PSL group was higher than that in the non-PSL group (3.56 ± 0.45 vs. 2.77 ± 0.31, p < 0.001). In logistic regression analysis, VBQ score (odds ratio, 3.425; 95% confidence interval, 1.552–8.279) were identified as independent risk factors for screw loosening. The area under the receiver operating characteristic curve for VBQ score predicting PSL was 0.819 (p < 0.05), with the optimal threshold of 3.15 (sensitivity, 83.1%; specificity, 80.5%).
Conclusion
The VBQ score can independently predict postoperative screw loosening in patients undergoing lumbar dynamic pedicle screw fixation with PEEK rods, and its predictive value is comparable to HU value.
7.Prediction of Screw Loosening After Dynamic Pedicle Screw Fixation With Lumbar Polyetheretherketone Rods Using Magnetic Resonance Imaging-Based Vertebral Bone Quality Score
Guozheng JIANG ; Luchun XU ; Yukun MA ; Jianbin GUAN ; Yongdong YANG ; Wenqing ZHONG ; Wenhao LI ; Shibo ZHOU ; JiaWei SONG ; Ningning FENG ; Ziye QIU ; Zeyu LI ; YiShu ZHOU ; Letian MENG ; Yi QU ; Xing YU
Neurospine 2024;21(2):712-720
Objective:
To investigate the correlation between magnetic resonance imaging-based vertebral bone quality (VBQ) score and screw loosening after dynamic pedicle screw fixation with polyetheretherketone (PEEK) rods, and evaluate its predictive value.
Methods:
A retrospective analysis was conducted on the patients who underwent dynamic pedicle screw fixation with PEEK rods from March 2017 to June 2022. Data on age, sex, body mass index, hypertension, diabetes, hyperlipidemia history, long-term smoking, alcohol consumption, VBQ score, L1–4 average Hounsfield unit (HU) value, surgical fixation length, and the lowest instrumented vertebra were collected. Logistic regression analysis was employed to assess the relationship between VBQ score and pedicle screw loosening (PSL).
Results:
A total of 24 patients experienced PSL after surgery (20.5%). PSL group and non-PSL group showed statistical differences in age, number of fixed segments, fixation to the sacrum, L1–4 average HU value, and VBQ score (p < 0.05). The VBQ score in the PSL group was higher than that in the non-PSL group (3.56 ± 0.45 vs. 2.77 ± 0.31, p < 0.001). In logistic regression analysis, VBQ score (odds ratio, 3.425; 95% confidence interval, 1.552–8.279) were identified as independent risk factors for screw loosening. The area under the receiver operating characteristic curve for VBQ score predicting PSL was 0.819 (p < 0.05), with the optimal threshold of 3.15 (sensitivity, 83.1%; specificity, 80.5%).
Conclusion
The VBQ score can independently predict postoperative screw loosening in patients undergoing lumbar dynamic pedicle screw fixation with PEEK rods, and its predictive value is comparable to HU value.
8.Prediction of Screw Loosening After Dynamic Pedicle Screw Fixation With Lumbar Polyetheretherketone Rods Using Magnetic Resonance Imaging-Based Vertebral Bone Quality Score
Guozheng JIANG ; Luchun XU ; Yukun MA ; Jianbin GUAN ; Yongdong YANG ; Wenqing ZHONG ; Wenhao LI ; Shibo ZHOU ; JiaWei SONG ; Ningning FENG ; Ziye QIU ; Zeyu LI ; YiShu ZHOU ; Letian MENG ; Yi QU ; Xing YU
Neurospine 2024;21(2):712-720
Objective:
To investigate the correlation between magnetic resonance imaging-based vertebral bone quality (VBQ) score and screw loosening after dynamic pedicle screw fixation with polyetheretherketone (PEEK) rods, and evaluate its predictive value.
Methods:
A retrospective analysis was conducted on the patients who underwent dynamic pedicle screw fixation with PEEK rods from March 2017 to June 2022. Data on age, sex, body mass index, hypertension, diabetes, hyperlipidemia history, long-term smoking, alcohol consumption, VBQ score, L1–4 average Hounsfield unit (HU) value, surgical fixation length, and the lowest instrumented vertebra were collected. Logistic regression analysis was employed to assess the relationship between VBQ score and pedicle screw loosening (PSL).
Results:
A total of 24 patients experienced PSL after surgery (20.5%). PSL group and non-PSL group showed statistical differences in age, number of fixed segments, fixation to the sacrum, L1–4 average HU value, and VBQ score (p < 0.05). The VBQ score in the PSL group was higher than that in the non-PSL group (3.56 ± 0.45 vs. 2.77 ± 0.31, p < 0.001). In logistic regression analysis, VBQ score (odds ratio, 3.425; 95% confidence interval, 1.552–8.279) were identified as independent risk factors for screw loosening. The area under the receiver operating characteristic curve for VBQ score predicting PSL was 0.819 (p < 0.05), with the optimal threshold of 3.15 (sensitivity, 83.1%; specificity, 80.5%).
Conclusion
The VBQ score can independently predict postoperative screw loosening in patients undergoing lumbar dynamic pedicle screw fixation with PEEK rods, and its predictive value is comparable to HU value.
9.Effect of ECT2 Gene on Proliferation of Cervical Cancer Cells and Its Mechanism
Yu CHEN ; Ziye SONG ; Yang GAO ; Hongbing CAI
Cancer Research on Prevention and Treatment 2022;49(10):1015-1020
Objective To study the effect of epithelial cell transformation sequence 2 (ECT2) on the proliferation of cervical cancer cells and its mechanism. Methods We transfected cervical cancer cells HeLa (HeLa-ECT2) with the lentivirus overexpressing ECT2 and the cells SiHa (SiHa-siRNA) and C33a (C33a-siRNA) with the interfering plasmid. MTT assay was performed to detect cell proliferation ability. Flow cytometry was conducted to detect the cell cycle of each group. The IPA database was searched for the interacting proteins of ETC2, and immunofluorescence subcellular localization verified the effect between the two. qPCR and Western blot were carried out to detect the expression of Rac1, Cdc42, CDK1, and Cyclin B1 mRNA and protein in each group of cells. Results ECT2 may interact with CDK1. After ECT2 expression was upregulated, the G2/M phase of HeLa-ECT2 cells accelerated the transformation to G1 phase, cell proliferation ability was enhanced, and the expression levels of Rac1, Cdc42, CDK1, and cyclin B1 mRNA and protein all increased (
10.Effects of smoking on the wound healing of stage 4 pressure ulcers in rats
Meiyi SONG ; Xian LI ; Shanshan LIU ; Yao WANG ; Zhihong ZHAO ; Yue WANG ; Ziye CHEN
Chinese Journal of Burns 2020;36(10):953-958
Objective:To explore the effect of smoking on the wound healing of stage 4 pressure ulcers in rats.Methods:Fifty male Sprague-Dawley rats aged 6-8 weeks were divided into simple pressure ulcer group and smoking+ pressure ulcer group according to the random number table, with 25 rats in each group. After the rats in the smoking+ pressure ulcer group received passive smoking intervention for 12 weeks, an iron plate was placed in the back muscle of each rat in 2 groups, and a magnet was placed outside the skin at the corresponding position of the iron plate for 2 h at each time, with 5 times a day and continuously for 6 days to reproduce stage 4 pressure ulcer model. Immediately after establishing the model, 3 rats in each group were sacrificed and wound tissue was collected, and hematoxylin-eosin staining was applied to observe the pathological changes of the wounds. On 1, 3, 7, and 14 day (s) after establishing the model, 3 rats in each group were collected to measure the pressure ulcer wound area by the paper jam method. After measurement of the wound area, the rats were sacrificed and the wound tissue was collected, and the protein expression levels of matrix metalloproteinases 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) in wound tissue were detected by immunohistochemical method, and the ratio of MMP-9/TIMP-1 was calculated.The wound healing time of the remaining 10 rats in each group was recorded. Data were statistically analyzed with analysis of variance for factorial design, two independent sample t test, and Bonferroni correction. Results:(1) Immediately after establishing the model, muscle fiber necrosis and dissolution with large areas were seen on the wound, the myofibrils arranged loosely, and more lymphocytes and monocytes infiltration were seen around the wound of rats in simple pressure ulcer group. A large number of necrotic myofibers were dissolved and gradually disappeared, the myofibrils arranged loosely, and the number of diffuse lymphocytes and monocyte infiltration in wound of rats in smoking+ pressure ulcer group were significantly higher than those in simple pressure ulcer group. (2) The wound areas of rats in smoking+ pressure ulcer group were significantly larger than those in simple pressure ulcer group on 1, 3, 7, and 14 day (s) after establishing the model ( t=3.019, 2.549, 2.181, 3.674, P<0.05 or P<0.01). (3) On 1 to 14 days after establishing the model, the protein expression levels of MMP-9 and TIMP-1 in the wound tissue and the ratio of MMP-9/TIMP-1 of rats in the two groups increased first and then decreased. On 1, 3, 7, and 14 day (s) after establishing the model, the protein expression levels of MMP-9 in the wound tissue and the ratio of MMP-9/TIMP-1 of rats in smoking+ pressure ulcer group were significantly higher than those in simple pressure ulcer group ( t=4.783, 4.508, 6.325, 7.204, 3.078, 2.989, 4.081, 4.696, P<0.05 or P<0.01), and the protein expression levels of TIMP-1 in wound tissue of rats in the two groups were similar. (4) The wound healing time of rats in smoking+ pressure ulcer group was (48.9±2.6) d, which was significantly longer than (35.2±2.3) d of simple pressure ulcer group ( t=12.477, P<0.05). Conclusions:Smoking can up-regulate the expression of MMP-9 in pressure ulcer wound and result in an imbalance of MMP-9/TIMP-1, thereby affecting the wound healing of stage 4 pressure ulcers in rats.

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