Objective A rat model of pulmonary fibrosis was constructed using a single or two intratracheal drops of bleomycin(BLM)and the modeling rate and stability of the two modeling modalities were compared.Methods A total of 150 specific pathogen-free SD rats were divided randomly into blank control(control),single intratracheal drop of bleomycin(BLM-S),and two intratracheal drops of bleomycin(BLM-M)groups.Rats in the BLM-S group received a single dose of 3 mg/kg BLM by noninvasive intratracheal instillation,and rats in BLM-M group received 3 mg/kg BLM on day 1 and BLM 2 mg/kg on day 14.Rats in the control group were given intratracheal instillation of 0.9％sodium chloride(1 mL/kg).The rats were euthanized on days 28,42,56,and 84 after modelling,respectively.Deep inspiratory capacity(IC),vital capacity(VC),static lung compliance(Cchord),and dynamic lung complication(Cdyn)were measured in all rats.Pathological changes in lung tissue were observed,and the extent of alveolitis and fibrosis was graded.Collagen-Ⅲ(COL-Ⅲ)expression in rat lung tissue was detected by immunohistochemistry.Results(1)The survival rates in the control,BLM-S,and BLM-M groups were 100％,80％,and 66％,respectively.Rats in the BLM-S and BLM-M groups had significantly lower body weights on days 14～42 compared with the control group(P＜0.05,P＜0.01),and rats in the BLM-M group had significantly lower body weight on days 28～42 than rats in the control and BLM-S groups(P＜0.05,P＜0.01).(2)Regarding lung function,IC,VC,Cchord,and Cdyn were all markedly decreased in the BLM-S group compared with the control group(P＜0.05,P＜0.01)and IC,VC,and Cchord were significantly decreased in the BLM-M group(P＜0.05,P＜0.01)on day 28.IC,VC,and Cchord were significantly decreased in rats in the BLM-S group on day 42(P＜0.05,P＜0.01),and were also significantly decreased in rats in the BLM-M group on days 42～84(P＜0.05,P＜0.01).(3)In terms of lung pathology,inflammatory infiltration and fibrous cords appeared in the BLM-S group from days 28～84 and then gradually decreased(P＜0.05,P＜0.01),while fibrosis and alveolitis were relatively stable in the BLM-M group(P＜0.05,P＜0.01).(4)COL-Ⅲ expression levels in lung tissue were significantly higher in rats in the BLM-S and BLM-M groups compared with the control group(P＜0.05,P＜0.01),and the COL-Ⅲ content in the BLM-S group was significantly lower at 42～84 days than at 28 days(P＜0.05).Conclusions Both method are capable of effectively creating pulmonary fibrosis models.The single-dose approach is straightforward,has a lower death rate,and the degree of fibrosis is clearly visible by day 28,but progressively recovers after 42 days.In contrast,the two-dose instillation model has a greater success rate and better stability,with over half the rats still exhibiting visible fibrosis on day 84.

Respiratory diseases(e.g.,lung inflammation and pulmonary fibrosis)are a serious threat to human health.Mitochondria,organelles unique to eukaryotic cells,not only have important functions in energy production,biosynthesis,and the maintenance of intracellular homeostasis but also act as diverse signaling organelles involved in inflammation,proliferation,differentiation,cell repair,and other processes.The mitochondrial quality control system involves mitochondrial biogenesis,dynamics,and autophagy.Certain pathological mechanisms of respiratory diseases,such as oxidative stress and inflammation,are closely related to the dysregulation of mitochondrial quality control systems.This paper summarizes the progress of research into mitochondrial quality control dysregulation in respiratory diseases(chronic obstructive pulmonary disease,pulmonary fibrosis,acute lung injury,asthma,and bacterial pneumonia)to explore new ideas for the prevention and treatment of respiratory diseases.

Objective To compare the success rate and stability of rat pulmonary fibrosis(PF)models induced by intratracheal instillation of different doses of bleomycin(BLM).Methods One hundred and fifty Sprague Dawley rats were divided randomly into control,low-dose BLM 3 mg/kg(BL-L),and high-dose BLM 5 mg/kg(BL-H)groups.General status,mortality,and weight changes were observed,and the lung inspiratory capacity(IC),vital capacity(VC),chord compliance(Cchord),and dynamic compliance(Cdyn)were detected on days 28,42,56,and 84.Lung coefficients were recorded and pathological changes in lung tissue were observed by hematoxylin and eosin and Masson staining.The lung hydroxyproline(HYP)content was detected and collagen type Ⅲ(COL Ⅲ)was detected by immunohistochemistry.Results The mortality rates in the BL-L and BL-H groups were 20％and 28％,respectively.Body weight was significantly lower in the BL-L group compared with the control group on days 0～56,and weight recovery after day 56.Body weight was significantly lower in the BL-H group compared with the control and BL-L groups from days 0～56(P＜0.01).Regarding lung function,IC,VC,Cchord,and Cdyn were significantly lower in the BL-L group compared with the control group on day 28(P＜0.01,P＜0.05),and IC and Cdyn were significantly lower in the BL-H group(P＜0.01).IC,VC,and Cchord were significantly decreased in the BL-L group on day 42(P＜0.01,P＜0.05),while IC,VC,Cchord,and Cdyn were significantly decreased in the BL-H group(P＜0.01,P＜0.05),and IC,VC,and Cchord were significantly lower compared with in the BL-L group(P＜0.01).Cchord was significantly lower in the BL-H group compared with the control and BL-L groups on day 56(P＜0.01).The lung coefficients on day 28 were significantly higher in the BL-L and BL-H groups compared with the control group(P＜0.01),and were significantly higher in the BL-H group from days 42～56 compared with the BL-L and control groups(P＜0.01).Regarding lung histopathology and immunohistochemistry,inflammatory infiltration,fibrotic streaks,and COL Ⅲ expression were observed in the BL-L group from days 28～56,and almost complete disappearance of the fibrotic lesions on day 84.In contrast,fibrotic lesions could be observed from days 28～84 in the BL-H group,with significantly elevated COL Ⅲ expression compared with the control group(P＜0.01).The HYP content was significantly higher in the BL-L group compared with the control group from days 28～42(P＜0.05,P＜0.01),and then gradually decreased,and the HYP content was significantly higher in the BL-H group than in the control group from days 28～84(P＜0.01).Conclusions Both 3 and 5 mg/kg BLM can successfully induce PF rat models.Rats treated with 3 mg/kg BLM developed fibrosis on day 28,which lasted until day 42 and then gradually recovered.Rats treated with 5 mg/kg BLM developed fibrosis on day 28,and the degree of fibrosis was more severe with the higher compared with the lower dose,with stable fibrotic lesions up to day 56 and moderate-to-severe fibrosis still present in half of the rats until day 84.

Objective To explore the interventional mechanism of Bufei Yishen formula on chronic obstructive pulmonary disease from pathway level.Methods Macrophage inflammatory model was established by LPS stimulation.Based on gene set enrichment analysis(GSEA)method,macrophage inflammation related pathways were screened,and normalized enrichment score(NES)was used to identify pathways that were reversed by traditional Chinese medicine treatment,revealing the interventional mechanism of Bufei Yishen formula and its compatibility.Results The NES of Bufei Yishen formula was-1377.23,among which the NES of Bushen compatibility was-485.07,that of Huoxue was-351.86,Huatan was-303.71,and Yiqi was-236.59.There were 213 significantly disturbed pathways reversed after the intervention of Bufei Yishen formula,among which there were 184 reversed pathways for Huoxue compatibility,147 reversed pathways for Bushen,134 reversed pathways for Huatan,133 reversed pathways for Yiqi,and the reversal rate was 75.41%,60.25%,54.92%,54.51%,respectively.90 pathways,including TGF-β production,were significantly reversed in the four compatibilities.Positive regulation of cytokine production involved in inflammatory response etc were specifically reversed pathways for compatibility.Conclusion The intensity of Bufei Yishen formula that reversed macrophage-inflammatory related pathways was in order of Bushen,Huoxue,Huatan and Yiqi compatibility.And the number of pathways that could be reversed by the compatibility of Bufei Yishen formula was Huoxue,Bushen,Huatan and Yiqi.Bufei Yishen formula could regulate the common and specific reversal pathways of the compatibilities to intervene the inflammatory response.

AIM:To investigate the effect of Tongsai granules(TSG)on epithelial barrier dysfunction in acute exacerbation of chronic obstructive pulmonary disease(AECOPD)and the underlying mechanism.METHODS:Twenty-four Sprague-Dawley rats were randomly divided into control group,model group,TSG group,and moxifloxacin(MXF)+salbutamol(STL)group.Rat COPD model was established over 8 weeks.On day 3 of week 9,the rats with COPD were intratracheally administered Klebsiella pneumoniae to establish the AECOPD model.On days 1 to 2 and 4 to 7 in week 9,saline was administered via oral gavage to the rats in control and model groups,and the rats in TSG and MXF+ STL groups were treated daily with TSG and MXF+STL by gavage,respectively.Peak expiratory flow(PEF),histopatho-logical changes,and the expression levels of interleukin-1β(IL-1β),IL-6,tumor necrosis factor-α(TNF-α),matrix me-talloproteinase 2(MMP2),MMP9,zonula occludens-1(ZO-1),E-cadherin(E-Cad)and occludin(OCC)were deter-mined.Moreover,human bronchial epithelial BEAS-2B cells were exposed to cigarette smoke extract(CSE)and treated with different TSG fractions,and the protein levels of ZO-1,E-Cad,OCC,epidermal growth factor receptor(EGFR),phosphorylated EGFR(p-EGFR),extracellular signal-regulated kinase(ERK)and phosphorylated ERK(p-ERK)were determined.RESULTS:Treatment with TSG significantly reduced bronchial wall thickness,mean linear intercept,and the levels of IL-1β,IL-6,TNF-α,MMP2 and MMP9(P＜0.05 or P＜0.01),significantly increased mean alveolar number and PEF(P＜0.01),and up-regulated the ZO-1,E-Cad and OCC protein levels(P＜0.01)in the lungs of AECOPD rats.Treatment with TSG2,the second TSG fraction,increased the protein levels of ZO-1,E-Cad and OCC in a dose-dependent manner in CSE-exposed BEAS-2B cells(P＜0.05 or P＜0.01).Network pharmacology analysis of 328 targets of the com-pounds in TSG2 and 3 864 genes related to AECOPD suggested that TSG2 relieved AECOPD likely through the regulation of ERBB2,ERK,EGFR,IL and WNT signaling pathways.Treatment with TSG2 also inhibited CSE-induced increases in p-EGFR and p-ERK levels in BEAS-2B cells(P＜0.05 or P＜0.01).CONCLUSION:Treatment with TSG could maintain airway epithelial barrier function in AECOPD rats,likely through the inhibition of EGFR/ERK signaling pathway.

AIM:This study aims to investigate the histopathological and ultrastructural alterations in the lung tissues of rats induced by a single intratracheal administration of bleomycin,with the objective of establishing a reliable model for future applications.METHODS:Six to eight-week-old SD rats were randomly allocated into two groups:the control group and the model group(n=12).Pulmonary fibrosis was induced in the rat models by a single intratracheal in-stillation of bleomycin(3 mg/kg),while an equivalent volume of saline was administered to the control group.The rats were executed on the 42nd day.Twelve rats remained in the control group,while nine rats remained in the model group.Lung tissue imaging was conducted using CT scans.Lung function tests were performed to assess changes in forced vital capacity(FVC)and dynamic lung compliance(Cdyn).Lung stiffness was determined through Young's modulus testing using a rheometer.The pathological structure of lung tissues was examined using both HE and Masson staining methods.Additionally,transmission electron microscopy was employed to evaluate collagen deposition in lung tissues,alveolar type Ⅱ epithelial cells,macrophages,and ultrastructural changes of the respiratory membrane.RESULTS:CT scans revealed honeycomb patterns in the lungs of model rats,along with partial bronchiectasis/bronchiectasis.In comparison to the con-trol group,the model group exhibited significantly lower FVC and Cdyn values,while lung stiffness were increased.HE and Masson staining demonstrated that rats in the model group exhibited alveolar structure destruction,alveolar septum thickening,inflammatory cell infiltration,and collagen deposition in alveolar septum.Transmission electron microscopy revealed several abnormalities in the model group:increased collagen fibers in the alveolar septa,misalignment of micro-villi in alveolar type Ⅱ epithelial cells,wrinkled nuclei with increased heterochromatin,swollen cytoplasmic mitochon-dria,fractured or haphazardly structured mitochondrion cristaes,and a significant decrease in their number(P＜0.05).Furthermore,lamellar bodies were vacuolated and reduced in number(P＜0.05),and dilated endoplasmic reticulums with degranulation were observed.There was an increase in alveolar macrophages and interstitial macrophages(P＜0.01).The respiratory membrane displayed structural disruptions and an increase in thickness(P＜0.01).CONCLUSION:Bleomycin induces decreased lung compliance,alveolar epithelial injury,alveolar septum thickening,collagen deposi-tion,and an increase in interstitial macrophages,ultimately resulting in pulmonary fibrosis in rats.

Pulmonary fibrosis(PF)is a progressive,interstitial fibrotic lung disease characterized by persistent scar formation in the lung parenchyma,and a reduced quality of life and poor prognosis for patients.The pathogenesis of PF is unknown and there is a lack of effective therapeutic agents;however,animal models are currently the main tool used to explore the pathogenesis of the disease and to find effective therapeutic agents.PF can be induced by various factors and to different degrees according to known etiologies.Among these,bleomycin-induced models are widely used because of their reproducibility and the similarity between the fibrosis pathology and clinical conditions.The main induction method include intratracheal drip,intratracheal nebulization,tail vein injection,intraperitoneal injection,and transnasal inhalation,and these can be classified into single and multiple doses,according to the frequency of induction.Based on the relevant literature,the current review summarizes the characteristics of the bleomycin-induced PF model using different induction frequencies and method,to provide a basis for the application of this model.

Objective To exploring the mechanism of Jinshui Chenfei formula(JCF)in ameliorating silica(SiO2)-induced silicosis fibrosis based on endogenous metabolite changes.Methods A total of 32 SPF male Sprague-Dawley(SD)rats were divided into normal control group,model group,JCF group(9.72 g·kg-1·d-1),and Tetrandrine group(27 mg·kg-1·d-1)according to random number table method.The experimental silicosis model was established by intratracheal injection with SiO2 suspension(250 mg/kg)on day 1.From week 5-8,silicosis rats were treated with tetrandrine or JCF.On the end of week 8,the changes of pulmonary function index,including forced vital capacity(FVC),tidal volume(TV)and lung dynamic compliance(Cydn)were detected.The pathological changes of lung tissue were analyzed by hematoxyline-osin(HE)staining and Masson staining,the severity of focal alveolitis and fibrosis was also evaluated using the Szapiel scale and the Ashcroft scale,the positive staining of collagen Ⅰ(COL Ⅰ)and COL Ⅲ was detected using immunohistochemistry;the protein expression of transforming growth factor-β1(TGF-β1),fibronectin(FN),andα-smooth muscle actin(α-SMA)were measured by Western blotting.The rat serum samples were further screened for differential metabolites using ultra performance liquid chromatographytandem quadrupole time of flight mass spectrometr(UPLC-Q-TOF-MS)and pathway analysis was performed based on MetaboAnalyst 5.0.Results Compared with those in the normal control group,pathological changes such as alveolar structure destruction,the fibrous nodules encapsulated SiO2 particles were increased in lung tissues of rats in model group,alveolitis score and pulmonary fibrosis score were significantly higher(alveolitis score:2.62±0.27 vs.0.20±0.15,pulmonary fibrosis score:5.42±0.66 vs.0.50±0.84,both P<0.01);pulmonary function index including Cydn,FVC,and TV were significantly decreased[Cdyn(mL/cmH2O):0.26±0.03 vs.0.33±0.03,FVC(mL):8.09±0.47 vs.10.99±0.38,TV(mL):1.95±0.19 vs.2.53±0.26,all P<0.01];positive staining of COL Ⅰ,COL Ⅲ and ɑ-SMA,FN,TGF-β1 proteins expression showed higher in lung tissues[positive staining of COL Ⅰ(A value):13.47±1.76 vs.5.77±0.45;positive staining of COL Ⅲ(A value):10.39±0.47 vs.6.19±0.77,FN protein expression(FN/GAPDH):0.33±0.02 vs.0.21±0.07,α-SMA protein expression(α-SMA/GAPDH):1.78±0.16 vs.1.11±0.24,TGF-β1 protein expression(TGF-β1/GAPDH):0.52±0.10 vs.0.11±0.46,all P<0.01].Compared with the model group,the pathological changes of lung tissues were almost restored,alveolitis score and lung fibrosis score were significantly reduced in JCF and Tetrandrine groups(alveolitis score:1.10±0.15,1.33±0.31 vs.2.62±0.27,pulmonary fibrosis score:3.50±0.45,4.33±0.98 vs.5.42±0.66,all P<0.01);the pulmonary function index Cydn,FVC and TV were significantly increased[Cdyn(mL/cmH2O):0.32±0.05,0.31±0.04 vs.0.26±0.03,FVC(mL):9.41±0.85,8.70±0.92 vs.8.09±0.47,TV(mL):2.70±0.19,2.27±0.15 vs.1.95±0.19,all P<0.05];positive staining of COL Ⅰ,COL Ⅲ,and protein expression of FN,ɑ-SMA,and TGF-β1 in lung tissues was significantly decreased[COL Ⅰ(A value):7.09±0.67,8.13±0.64 vs.13.47±1.76,COL Ⅲ(A value):8.19±0.66,8.52±0.22 vs.10.39±0.47,FN protein expression(FN/GAPDH):0.19±0.06,0.24±0.03 vs.0.33±0.02,α-SMA protein expression(α-SMA/GAPDH):0.89±0.41,0.88±0.08 vs.1.78±0.16,TGF-β1 protein expression(TGF-β1/GAPDH):0.04±0.03,0.06±0.01 vs.0.52±0.10,all P<0.05].Metabolomics analysis showed that a total of 10 major differential metabolites were identified between normal control group,model group and JCF group,including arachidonic acid,palmitic acid,indole-3-acetic acid,propionylcarnitine,(S)-4-hydroxymandelonitrile,nalidixic acid,benzocaine,gramine,4-ethylphenol,N-benzylfor mamide.The differential metabolites in silicosis rats reversed by JCF treatment were mainly enriched,including unsaturated fatty acid biosynthesis,arachidonic acid metabolism,tryptophan metabolism,fatty acid elongation,fatty acid degradation and biosynthesis.Conclusion JCF could effectively improve the silicosis fibrosis,which is mainly related to biosynthesis of unsaturated fatty acids biosynthesis,arachidonic acid metabolism,tryptophan metabolism,fatty acid elongation,fatty acid degradation and biosynthesis.

Pneumoconiosis is an occupational lung disease with the highest incidence in China. There is no effective treatment drug at present. Animal and cell models are the basis for exploring its pathogenesis and developing effective drugs. In this paper, we sort out the methods of animal models of pneumoconiosis and the different cell models induced by dust in recent years, by analyzing and summarizing the advantages and disadvantages, modeling time, pathology and changes in important indicators of different preparation methods of animal models, as well as different cell models induced by the dust to simulate different pathological models and pathological stages, to provide basis for the application and improvement of pneumoconiosis model.

Pneumoconiosis is an occupational lung disease with the highest incidence in China. There is no effective treatment drug at present. Animal and cell models are the basis for exploring its pathogenesis and developing effective drugs. In this paper, we sort out the methods of animal models of pneumoconiosis and the different cell models induced by dust in recent years, by analyzing and summarizing the advantages and disadvantages, modeling time, pathology and changes in important indicators of different preparation methods of animal models, as well as different cell models induced by the dust to simulate different pathological models and pathological stages, to provide basis for the application and improvement of pneumoconiosis model.