1.Thyroid Hormone Network Regulation in MASLD: Mechanisms and Targeted Therapies
Wen-Ping XIAO ; Yang MA ; Heng GUAN ; Sha WAN ; Wen HAN ; Bing-Bing LUO ; Wu-Feng WANG ; Fang LIU
Progress in Biochemistry and Biophysics 2026;53(3):643-661
Metabolic dysfunction-associated steatotic liver disease (MASLD) has become the most prevalent chronic liver disease worldwide, affecting approximately 32%-38% of the adult population and posing a growing public health burden. MASLD represents a continuous disease spectrum ranging from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH), progressive hepatic fibrosis, cirrhosis, and ultimately hepatocellular carcinoma (HCC). The pathological core of MASLD lies in disruption of hepatic lipid metabolic homeostasis, characterized by an imbalance among de novo lipogenesis, fatty acid β-oxidation, and very-low-density lipoprotein (VLDL)-mediated lipid export. This metabolic disequilibrium subsequently drives inflammatory injury and fibrotic progression. Among the multiple regulatory pathways involved, thyroid hormone (TH) signaling has emerged as a central regulator of hepatic metabolic homeostasis. The liver is a major peripheral target organ of TH action, where TH predominantly exerts its metabolic effects through thyroid hormone receptor β (TRβ). Large-scale epidemiological studies and meta-analyses have demonstrated that hypothyroidism is significantly associated with increased MASLD prevalence, more severe histological injury, and advanced hepatic fibrosis, suggesting that dysregulation of TH signaling may participate throughout the entire MASLD disease spectrum. At the molecular level, TH regulates hepatic lipid metabolism by coordinating suppression of lipogenesis, enhancement of mitochondrial fatty acid oxidation, and promotion of VLDL assembly and secretion through integrated genomic actions of the T3-TRβ axis and non-genomic signaling pathways. Across different stages of MASLD, TH signaling exerts stage-dependent protective effects. In the steatosis stage, TH improves metabolic flexibility by modulating insulin sensitivity, glucose metabolism, and lipid droplet clearance, thereby alleviating early lipotoxic stress. During progression to MASH, TH attenuates inflammatory amplification by improving mitochondrial homeostasis, suppressing activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, and modulating the gut-liver axis microenvironment. In advanced stages, TH signaling influences hepatic stellate cell activation and extracellular matrix deposition, partly through interaction with the transforming growth factor-β (TGF-β)/SMAD pathway, while alterations in intrahepatic TH availability, mediated by dynamic changes in iodothyronine deiodinase 1 (DIO1), contribute to fibrosis progression and hepatocellular dedifferentiation. In hepatocellular carcinoma, coordinated downregulation of TRβ and DIO1 establishes a tumor-associated hypothyroid state that promotes metabolic reprogramming and tumor progression. The clinical relevance of TH signaling in MASLD has been underscored by the recent approval of Resmetirom, a liver-targeted TRβ‑selective agonist, for the treatment of non-cirrhotic MASH with moderate-to-severe fibrosis (F2-F3). This approval represents a landmark transition from mechanistic understanding to metabolism-centered precision therapy in MASLD. Clinical trials have demonstrated that Resmetirom not only improves key histological endpoints, including MASH resolution and fibrosis regression, but also favorably modulates atherogenic lipid profiles, highlighting the therapeutic potential of selectively targeting hepatic TH pathways. This review systematically summarizes the multidimensional regulatory roles of TH across the MASLD disease spectrum and discusses emerging diagnostic and therapeutic implications of TH-based interventions, aiming to inform future mechanistic research and optimize clinical management strategies.
2.Establishment and Preliminary Analysis of GP73 Interactome Using Proximity-dependent Labeling Technology
Mu-Yi LIU ; Chang ZHANG ; Meng-Xin YANG ; Xin-Long YAN ; Lu-Ming WAN ; Cong-Wen WEI
Progress in Biochemistry and Biophysics 2026;53(3):711-723
ObjectiveProtein-protein interactions (PPIs) are fundamental to the execution of biological functions within living cells. However, traditional biochemical methods, such as co-immunoprecipitation (Co-IP), often fail to capture transient, weak, or membrane-associated interactions due to the stringent detergent requirements for cell lysis. Proximity labeling (PL) has emerged in recent years as a transformative technology for mapping the proteomes of specific subcellular compartments and identifying dynamic interactomes in situ. Golgi protein 73 (GP73, also known as GOLPH2), a resident type II Golgi transmembrane protein, is a well-recognized clinical biomarker for liver diseases, including hepatocellular carcinoma (HCC). Despite its clinical significance, the comprehensive physiological and pathological functions of GP73 remain partially understood. This study aims to establish an APEX2-mediated proximity labeling system specifically targeting GP73 to map its interactome in a living cellular environment, thereby providing new insights into its molecular roles and regulatory mechanisms. MethodsTo achieve spatial specificity, we first constructed a stable cell line expressing a fusion protein consisting of GP73 and the engineered soybean peroxidase APEX2. The localization of the GP73-APEX2 fusion protein was validated to ensure it correctly targeted the Golgi apparatus. The proximity labeling reaction was initiated by incubating the cells with biotin-phenol (BP) for 30 min, followed by a brief (1 min) treatment with1 mmol/L hydrogen peroxide (H2O2). This catalytic reaction converts BP into highly reactive, short-lived biotin-phenoxyl radicals that covalently attach to endogenous proteins within a small labeling radius of the GP73-APEX2 enzyme. Subsequently, the cells were quenched, and biotinylated proteins were enriched using high-affinity streptavidin-coated magnetic beads. The captured “neighbor” proteins were subjected to on-bead digestion and analyzed via liquid chromatography-tandem mass spectrometry (LC-MS/MS) for high-throughput identification. Rigorous bioinformatics analysis, including Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and protein-protein interaction network mapping, was performed to interpret the biological significance of the identified candidates. ResultsOur results demonstrate the successful establishment of a robust and sensitive APEX2-based proximity labeling system for GP73. We identified a total of 95 high-confidence interacting proteins that were significantly enriched in the GP73 proximity proteome compared to control groups. Bioinformatics analysis revealed that these interactors were predominantly associated with biological processes such as vesicular transport, protein localization, and, most notably, molecular functions related to “ribosome binding” and “translation regulation”. This suggested an unexpected role for the Golgi-resident GP73 in the cellular translation machinery. To validate these findings, we performed targeted biochemical assays which confirmed a direct interaction between GP73 and the subunits of the eukaryotic translation initiation factor 3 (eIF3) complex, specifically EIF3G and EIF3I. Furthermore, functional validation using the surface sensing of translation (SUnSET) assay—a non-radioactive method to monitor protein synthesis—revealed that the overexpression of GP73 significantly promoted global protein translation levels in the cell, whereas its depletion or inhibition resulted in reduced translation efficiency. ConclusionThis study successfully utilized APEX2-mediated proximity labeling to provide the first systematic map of GP73 interactome in living cells. Our findings uncover a novel, unconventional function of GP73 as a regulator of cellular protein translation, likely mediated through its interaction with the eIF3 complex. This discovery significantly broadens our understanding of the biological roles of GP73 beyond its traditional function in the Golgi apparatus and suggests that it may act as a bridge between Golgi-related trafficking and the protein synthesis machinery. Furthermore, the technical framework established in this study provides a valuable template for investigating other complex organelle-associated protein networks and resolving transient macromolecular interactions in various physiological and pathological contexts.
3.Expert recommendations on vision friendly built environments for myopia prevention and control in children and adolescents
Chinese Journal of School Health 2026;47(1):1-5
Abstract
The prevention and control of myopia in Chinese children and adolescents has become a major public health issue. While maintaining increased outdoor activity as a cornerstone intervention, there is an urgent need to explore new complementary approaches that can be effectively implemented in both indoor and outdoor settings. In recent years, environmental spatial frequency has gained increasing attention as one of the key environmental factors influencing the development and progression of myopia. Both animal studies and human research have confirmed that indoor environments lacking mid to high spatial frequency components, often characterized as "visually impoverished", can promote axial elongation and myopia through mechanisms such as disruption of retinal neural signaling, impaired accommodative function, and altered expression of related molecules. Based on the scientific consensus, it is recommended that "enriching of environmental spatial frequency" should be integrated into the myopia prevention and control framework. Following the principles of schoolled organization, family cooperation, community involvement, and student participation, specific measures are put forward in three areas:optimizing school visual settings, improving home spatial environments, and promoting healthy visual behavior. The aim is to create "visually friendly" indoor environments as an important supplement to outdoor activity, thereby providing a novel perspective and strategy for comprehensively advancing myopia prevention and control among children and adolescents.
4.Association of vegetables and fruits intake with depressive symptoms in Yunnan multi ethnic first year junior high school students
CHEN Yiyao*, DU Yeming, YIN Wan, HUANG Jianhong, LIU Zihan, JIANG Yinghong, YU Qiaoying, PAN Lijuan, XU Honglü ;
Chinese Journal of School Health 2026;47(1):32-36
Objective:
To explore the association of vegetables and fruits intake with depressive symptoms among multi ethnic first year junior high school students in Yunnan Province, so as to provide data support for preventing and reducing depressive symptoms among first year junior high school students.
Methods:
From October to December 2022, a cluster random sampling method was used to select 8 500 first year junior high school students from 11 ethnic minority areas in Yunnan Province (Fugong County, Longling County, Longyang District, Luchun County, Mojiang County, Nanjian County, Qiaojia County, Shuangjiang County, Tengchong City, Yuanmou County, Zhenyuan County), to investigate with a questionnaire. The Dietary Frequency Questionnaire was used to collect dietary behavior datas, and the Chinese version of Depression Anxiety Stress Scale-21 (DASS-21) was used to assess depressive symptoms. The generalized linear model was used to analyze the association of vegetable and fruit intake with depressive symptoms in students, and stratified analysis was performed according to ethnicity.
Results:
The detection rate of depressive symptoms among first year junior high school students in Yunnan Province was 29.5%. The detection rates of depressive symptoms in Han and minority first year junior high school students were 26.9% and 31.6%. After controlling for demographic variables such as gender, age, family residence and other confounding factors, the generalized linear model analysis results showed that the intake of leafy vegetables ( β= -0.07 , 95%CI =-0.12 to -0.01), flat fruits ( β=-0.06, 95%CI =-0.12 to -0.00) and hot natured fruits ( β=0.11, 95%CI = 0.04- 0.17) were associated with depressive symptoms in Han first year junior high school students (all P <0.05). The intake of melon and fruit vegetables ( β=-0.06, 95%CI =-0.11 to -0.01) and hot natured fruits ( β=0.06, 95%CI =0.01-0.12) were associated with depressive symptoms in ethnic minority first year junior high school students (both P <0.05).
Conclusions
The intake of vegetables and fruits among multi ethnic first year junior high school students in Yunnan Province is related to the risk of depressive symptoms. It is suggested to strengthen the consumption guidance and education of vegetables and fruits to prevent depressive symptoms among first year junior high school students.
5.Analysis of Microbiological and Parasitic Testing Results for Laboratory Animals in Jiangxi Province, 2020-2024
Fangping XIAO ; Lijuan XIONG ; Bo JIA ; Huan LIU ; Yongbing LUO ; Xiaorong WAN
Laboratory Animal and Comparative Medicine 2026;46(1):119-126
Objective To assess the current status of microbial and parasitic quality control for laboratory animals in Jiangxi Province by analyzing microbiological and parasitic test results from production facilities between 2020 and 2024, and to provide a basis for enhancing quality control measures. MethodsIn accordance with the current national standards for laboratory animals at the time of testing, the Jiangxi Provincial Laboratory Animal Quality Inspection Station (affiliated to Institute of Occupational Medicine of Jiangxi) conducted microbial and parasitic testing on 451 laboratory animals of 4 species from 6 laboratory animal production units in Jiangxi Province between 2020 and 2024, and analyzed the quality status of laboratory animals in the province. ResultsPasteurella pneumotropica was detected in one mouse sample in 2020, with a detection rate of 5.00%. Pseudomonas aeruginosa was detected in one mouse sample and mouse hepatitis virus antibody was detected in another mouse sample in 2023, with a detection rate of 2.78%, respectively. No microorganisms or parasites that should be excluded from SPF grade mice as specified in the national standards were detected in 2021, 2022, or 2024, with a qualification rate of 100.00%. Pasteurella pneumotropica was detected in four rat samples in 2020, with a detection rate of 20.00%. Pseudomonas aeruginosa was detected in two rat samples in 2021, with a detection rate of 10.00%, and Tyzzer's disease agent antibody was detected in four rat samples in 2024, with a detection rate of 10.00%. No microorganisms or parasites that should be excluded from SPF grade rats as specified in the national standards were detected in 2022 or 2023, with a qualification rate of 100.00%. For rabbits and guinea pigs, no microorganisms or parasites required to be tested for conventional grade rabbits and guinea pigs as specified in the national standards were detected from 2020 to 2024, with the qualification rate of both species reaching 100.00%. ConclusionBased on the microbial and parasitic testing results, the quality of rabbits and guinea pigs in Jiangxi Province is satisfactory. However, some issues persist with rats and mice. It is recommended to enhance the quality of experimental animals in Jiangxi Province by increasing the frequency of random inspections by quality testing units or by improving the self-inspection capabilities of production and user facilities.
6.Ancient and Modern Application and Key Information Analysis of Classic Formula Erchentang
Qing TANG ; Lyuyuan LIANG ; Jialei CAO ; Lan LIU ; Hejia WAN ; Chengxin LUO ; Bingqi WEI ; Yamin KONG ; Bingxiang MA ; Wenli SHI
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(1):262-270
Erchentang is a classic formula widely used by medical practitioners throughout history. In this paper,ancient and modern literature of Erchentang were collected, and bibliometrics was employed to analyze its historic evolution,prescription meaning,herbs origin, processing method,preparation methods, and clinical application. A total of 84 pieces of data were collected, and 58 pieces of data involving 53 ancient medical Chinese books were screened, sorted, and processed. Combined with research of modern scholars,the research has found that the Erchentang originated from the Taiping Huimin Huiye Shijie Fang compiled by the Imperial Medical Bureau of the Song Dynasty. The basic information about the origin of the drugs is quite clear. Pinelliae rhizoma in the formula is the dried tuber of Pinellia ternata. Citri exocarpium rubrum is the dried mature peel of Citrus reticulata and its cultivated varieties, with the inner white membrane removed. Poria is the whitest dry sclerotia of Poria cocos; Glycyrrhizae radix et rhizoma is the dried root and rhizome of the Glycyrrhiza uralensis. The dosage is 5.70 g Pinelliae rhizome and Citri exocarpium rubrum, 3.43 g Poria, and 1.69 g Glycyrrhizae radix et rhizoma praeparata cum melle. During the decoction process, the above-mentioned herbs should be chopped, with 300 mL water, 7 g ginger in thick slices, and 2 g Mume fructus added, and it was then simmered together to 180 mL. After removing the medicinal residue, it can be taken warmly. Erchentang has the effect of drying dampness and resolving phlegm, regulating Qi and harmonizing the middle. It can be used in treating the syndrome of phlegm and dampness,as well as symptoms such as frequent cough,white phlegm,fullness in chest and diaphragm,nausea and vomiting,limb drowsiness,anorexia,dizziness,palpitations,white and greasy tongue coating, and slippery pulse. The above results provide reference for future research and development of Erchentang.
7.Preliminary application of histological evaluation of donor pancreas biopsy tissue in simultaneous pancreas-kidney transplantation
Jiao WAN ; Hui GUO ; Jiali FANG ; Guanghui LI ; Luhao LIU ; Yunyi XIONG ; Wei YIN ; Tong YANG ; Junjie MA ; Zheng CHEN
Organ Transplantation 2026;17(2):250-256
Objective To preliminarily investigate the safety and efficacy of donor pancreas needle biopsy in simultaneous pancreas-kidney transplantation. Methods Clinical data of 7 cases undergoing donor pancreas biopsy were collected retrospectively. All cases underwent donor pancreas biopsy before or during simultaneous pancreas-kidney transplantation. Frozen section or paraffin sectioning techniques were used for tissue preparation, and hematoxylin-eosin and Masson staining were performed to histologically evaluate the donor pancreas. The quality of donor pancreas was comprehensively assessed by combining histological findings with the donor's clinical data. Postoperative follow-up data of 5 simultaneous pancreas-kidney transplant recipients were collected to summarize the safety of donor pancreas biopsy and the prognosis of transplant recipients. Results The 7 pancreas donors were aged 28 to 62 years, with a body mass index ranging from 20.76 to 27.68 kg/m2. Liver ultrasound indicated fatty liver in 3 cases, while pancreatic ultrasound did not reveal any significant abnormalities. Among them, biopsy was performed on 2 donors after completion of pancreatic procurement and processing, and the frozen section histology showed moderate acute pancreatitis changes (edema of acinar cells, necrosis and inflammatory cell infiltration). Combined with a serum amylase level elevated more than 3 times the upper limit of normal value, these two donor pancreases were finally discarded. The remaining 5 cases underwent biopsy immediately after pancreatic vascular anastomosis during simultaneous pancreas-kidney transplantation, and histological evaluation was performed on paraffin-embedded sections. No biopsy-related complications (such as bleeding, pancreatic fistula, etc.) occurred after transplantation. One recipient died of severe infection 2 months after transplantation, while the other 4 recipients were followed up for more than 5 years, with well-functioning transplant kidneys and pancreases. Conclusions Donor pancreas biopsy is relatively safe, and the risk of biopsy-related complications after transplantation is controllable. Comprehensive assessment of donor pancreas quality by combining histological evaluation with the donor's clinical indicators is conducive to improving the accuracy of donor pancreas selection and organ utilization.
8.Human umbilical cord mesenchymal stem cell-derived exosomes attenuate renal ischemia-reperfusion injury by up-regulating ATF3 to inhibit the TLR4/NF-κB pathway
Xingyu* WAN ; Yujia LIU ; Ruiyan WANG ; Hao WANG ; Yi ZHAO ; Lu GUO ; Zhihua YANG ; Xinghua LÜ
Organ Transplantation 2026;17(2):275-286
Objective To investigate the protective effect and underlying mechanism of human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Exo) on renal ischemia-reperfusion injury (IRI). Methods hucMSC-Exos were isolated and characterized. A mouse renal IRI model was established and the animals were divided into Sham, IRI, IRI+hucMSC-Exo, IRI+hucMSC-Exo+JY-2 and Sham+JY-2 groups. Serum creatinine (Scr) and blood urea nitrogen (BUN) were measured. Hematoxylin-eosin (HE) staining was used to evaluate renal histopathology. Enzyme-linked immune absorbent assay was performed to determine serum interleukin (IL)-1β and IL-18 levels. Western blotting was used to detect the expression of activating transcription factor 3 (ATF3), Toll-like receptor 4 (TLR4), nuclear factor (NF)-κB, NOD-like receptor protein 3 (NLRP3), cysteineyl aspartate specific proteinase (Caspase)-1 p20 and Gasdermin D(GSDMD). Real-time fluorescent quantitative polymerase chain reaction was employed to measure ATF3, TLR4 and NF-κB messenger RNA (mRNA). Immunohistochemistry was conducted to examine NLRP3, Caspase-1 p20 and GSDMD. An in vitro hypoxia/reoxygenation (H/R) model was established in HK-2 cells and divided into Control, H/R, H/R+hucMSC-Exo, H/R+hucMSC-Exo+JY-2 and Control+JY-2 groups. Western blotting was used to detect the expression of ATF3, TLR4 and NF-κB. Real-time fluorescent quantitative polymerase chain reaction was used to measure NLRP3, GSDMD and Caspase-1 mRNA. Results HucMSC-Exos were successfully isolated and identified. Compared with the Sham group, the IRI group exhibited elevated Scr and BUN, higher tubular injury scores, increased protein expression levels of ATF3, TLR4, NF-κB p65, NLRP3, Caspase-1 p20 and GSDMD, and raised mRNA expression levels of ATF3, TLR4, NF-κB. Compared with the IRI group, the IRI+hucMSC-Exo group showed decreased Scr and BUN, lower tubular injury scores, up-regulated ATF3 protein and mRNA, down-regulated TLR4, NF-κB p65, NLRP3, Caspase-1 p20 and GSDMD protein, and declined TLR4 and NF-κB mRNA. Compared with the IRI+hucMSC-Exo group, the IRI+hucMSC-Exo+JY-2 group exhibited increased Scr and BUN levels, elevated renal tubular injury scores, decreased ATF3 protein expression levels, elevated protein expression levels of TLR4, NF-κB p65, NLRP3, Caspase-1 p20, and GSDMD, decreased ATF3 mRNA expression levels, and elevated mRNA expression levels of TLR4 and NF-κB. (all P < 0.05). Compared with the Control group, the expression levels of ATF3, TLR4 and NF-κB p65 proteins were increased in the H/R group, and the expression levels of NLRP3, Caspase-1 and GSDMD mRNA were increased. Compared with the H/R group, the expression level of ATF3 protein was increased, the expression levels of TLR4 and NF-κB p65 proteins were decreased, and the expression levels of NLRP3, Caspase-1 and GSDMD mRNA were decreased in the H/R+hucMSC-Exo group. Compared with the H/R+hucMSC-Exo group, the expression level of ATF3 protein was decreased, the expression levels of TLR4 and NF-κB p65 proteins were increased, and the expression levels of NLRP3, Caspase-1 and GSDMD mRNA were increased in the H/R+hucMSC-Exo+JY-2 group (all P < 0.05). Conclusions HucMSC-Exos alleviate renal IRI by up-regulating ATF3, thereby negatively regulating the TLR4/NF-κB signaling pathway and subsequently inhibiting pyroptosis.
9.Introduction and enlightenment of the Recommendations and Expert Consensus for Plasma and Platelet Transfusion Strategies in Critically Ill Children Following Severe Trauma, Traumatic Brain Injury, and/or Intracranial Hemorrhage: From the Transfusion and Anemia Expertise Initiative-Control/Avoidance of Bleeding
Zhenzhen JIANG ; Rong GUI ; Rong HUANG ; Junhua ZHANG ; Jiaohui ZENG ; Hao TANG ; Zhi LIN ; Dan WAN ; Mingyi ZHAO ; Minghua YANG ; Lan GU ; Haiting LIU
Chinese Journal of Blood Transfusion 2026;39(2):285-293
Transfusion and Anemia Expertise Initiative-Control/Avoidance of Bleeding developed a strategy for platelet and plasma infusion management in critically ill children based on systematic reviews and consensus meetings of international multidisciplinary experts. One good practice statement and six expert consensus statements were proposed for plasma and platelet transfusions in critically ill children following severe trauma, traumatic brain injury, and/or intracranial hemorrhage. This article introduces the specific methods and basis for the formation of recommendations in this part of the guide.
10.Mechanism of Number 2 Feibi Recipe in Ameliorating Pulmonary Fibrosis in Mice by Modulating Endoplasmic Reticulum Stress in AT2 Cells to Attenuate Apoptosis and Promote Alveolar Repair
Yaodong CAI ; Jialing BEI ; Wan WEI ; Chengyan XU ; Yanli LIU ; Yong WANG ; Yang JIAO ; Yun CHEN
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):80-92
ObjectiveTo investigate the intervention mechanism of the traditional Chinese medicine Number 2 Feibi recipe (N2FBR) in idiopathic pulmonary fibrosis (IPF), focusing on its effects on endoplasmic reticulum (ER) stress, apoptosis, stemness maintenance, and regenerative capacity of alveolar type Ⅱ epithelial cells (AT2 cells), and to validate the modern translational pathway of the theory of "deficiency of Zong Qi leading to pulmonary atelectasis and atrophy". MethodsA mouse model of pulmonary fibrosis was induced by bleomycin (BLM). Mice were randomly divided into blank control, model, low-, and high-dose N2FBR intervention groups (9.1, 18.2 g·kg-1), and prednisolone intervention group (6.5 mg·kg-1). Pulmonary histopathological changes and collagen deposition were evaluated using hematoxylin-eosin (HE) and Masson's trichrome staining. Hydroxyproline (HYP) content was measured by the alkaline hydrolysis method. Lung coefficient and pulmonary function parameters were evaluated. The mRNA expression levels of fibrosis-related factors, including collagen type Ⅰ alpha 1 chain (ColIa1), alpha-smooth muscle actin (α-SMA), and tissue inhibitor of metalloproteinase 1 (Timp1), were detected by real-time polymerase chain reaction (Real-time PCR). Cell apoptosis was assessed using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Apoptosis of AT2 cells was further evaluated by double immunofluorescence staining for surfactant protein C (SPC) and cysteine-aspartic protease-3 (Caspase-3). Endoplasmic reticulum (ER) stress in AT2 cells was examined by double staining for SPC and protein kinase R-like endoplasmic reticulum kinase (PERK). Ultrastructural changes of ER and lamellar bodies in AT2 cells were observed by transmission electron microscopy (TEM). The expression levels of key proteins involved in ER stress and apoptosis pathways, including PERK, activating transcription factor 4 (ATF4), and Caspase-3, were detected by Western blot. Double immunofluorescence staining of SPC and Ki-67 antigen (Ki-67) was performed to evaluate the proliferative capacity of AT2 cells. Lineage tracing technology (labeling AT2 cells with GFP) combined with Krt8 labeling was used to evaluate intermediate differentiation states, and morphological transformation of AT2 cells into alveolar type Ⅰ epithelial cells (AT1) was observed. ResultsBLM-induced mice exhibited significant structural disruption of lung tissue, increased collagen deposition, elevated lung coefficient, decreased pulmonary function, and upregulation of fibrosis-related factors (P<0.01). High-dose N2FBR treatment significantly ameliorated lung tissue damage and dysfunction, significantly reduced HYP content (P<0.01), and significantly downregulated ColIa1, α-SMA, and Timp1 expression (P<0.01). Apoptosis analysis showed increased TUNEL-positive and Caspase-3-positive AT2 cells in the model group, which was significantly reduced by high-dose N2FBR treatment. TEM revealed swollen ER structures in AT2 cells of the model group, which tended to return to normal following treatment. PERK protein staining analysis showed evident ER stress in AT2 cells of the model group, which were markedly alleviated in the treatment group. The expression levels of ER stress-related proteins PERK and ATF4, as well as the apoptosis-related protein Caspase-3, were elevated in the model group and significantly reduced after treatment. TEM also revealed disrupted lamellar body structures in the model group, which tended to recover in the treatment group. Regarding the proliferative capacity of AT2 cells, the proportion of Ki-67⁺SPC⁺ AT2 cells significantly increased in the treatment group (P<0.01). Lineage tracing showed that the proportion of keratin 8-positive green fluorescent protein-positive (Krt8⁺GFP⁺) cells increased in the model group, indicating differentiation arrest. This proportion was significantly reduced in the treatment group, and the morphology of GFP⁺ cells exhibited a flattened, extended shape, suggesting restored differentiation toward AT1 cells. ConclusionN2FBR alleviates ER stress in AT2 cells, reduces AT2 cell apoptosis, restores lamellar body structure and function, enhances proliferation activity, and alleviates differentiation arrest to promote differentiation into AT1 cells, thereby repairing the alveolar epithelium and effectively blocking the progression of pulmonary fibrosis. Its traditional Chinese medicine mechanism of "replenishing Zong Qi, harmonizing Qi and blood, and unblocking pulmonary meridians" closely aligns with the modern regulatory pathway of AT2 stem cells, providing a novel theoretical basis and experimental evidence for the intervention of IPF with traditional Chinese medicine.


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