Mechanisms and Targeted Therapy of Airway Basal Cell Dysfunction in Bronchiolitis Obliterans Syndrome

N/AEnrolling By InvitationNCT07018804

Haikou Affiliated Hospital of Central South University Xiangya School of Medicine5 enrolled

Overview

This experimental study aims to investigate the pathogenesis of bronchiolitis obliterans syndrome (BOS) and provide a basis for clinical diagnosis and treatment. The core research question is: whether there is a causal relationship between stem cell dysfunction induced by the inflammatory microenvironment and airway injury repair during the pathological process of BOS? Researchers will collect alveolar lavage fluid specimens from participants and healthy individuals to isolate distal small airway stem cells for subsequent scientific research and comparative analysis, thereby revealing the pathological mechanisms of BOS, exploring precise intervention targets, and developing innovative therapeutic strategies to improve patient prognosis, long-term survival rates, and quality of life.

The purpose of this experimental study is to explore the role of airway basal cells in the development of bronchiolitis obliterans syndrome (BOS) and develop potential therapeutic strategies. The main question it aims to answer is: How do the functional abnormalities of airway basal cells (BCs) affect the progression of BOS and what are the underlying molecular mechanisms? Researchers will collect epithelial mucosal tissues from diseased and relatively healthy lung regions of BOS patients through bronchoscopic brushing, and simultaneously gather alveolar lavage fluid specimens when possible. Specimens from healthy volunteers with no obvious airway abnormalities will be used as controls. After that, BCs will be isolated from these specimens. The isolated BCs will be cultured and their molecular characteristics will be identified using immunofluorescence staining to detect the expression of BCs markers such as p63 and Krt5. Subsequently, single - cell clone libraries will be established by flow cytometry cell fluorescence sorting (FACS) technology. Multiple aspects of the cells' functions will be evaluated, including self - renewal ability by detecting the expression of the proliferation marker Ki67 through immunofluorescence and CCK8 assay, and differentiation ability by analyzing the cell types and proportions in the differentiation structures of in vitro air - liquid interface (ALI) culture for 21 days and in vivo differentiation in severe combined immunodeficiency (NSG) mice for 28 days using Real - time PCR and immunofluorescence techniques. In addition, multi - omics sequencing technologies, such as RNA - seq, ATAC - seq, and CUT\&Tag, will be employed to explore the molecular mechanisms of BCs' functional abnormalities. Stable interference cell lines will be established using CRISPR - Cas9 technology to verify the functions of potential target genes. A ferret BOS model will be constructed, and BCs transplantation experiments will be carried out in ferrets. By observing and analyzing the survival rate, body weight, CT images, and lung tissue pathology of ferrets, the preventive and therapeutic effects of BCs on BOS will be evaluated. By clarifying the role of BCs in BOS, this study aims to reveal the underlying pathological mechanisms, explore potential intervention targets, and develop novel treatment approaches. These efforts are expected to improve the prognosis of BOS patients, reduce the incidence and mortality rates, and enhance the overall quality of life for those affected by this life - threatening respiratory disorder.

Interventions

Bronchoscopic brushingPROCEDURE

The collected samples are digested with tissue collagenase for the culture of airway basal cells (BCs).

Single - cell cloningGENETIC

After primary BCs are expanded in the P1 passage, single-cell cloning libraries are established by planting them into 384-well cell culture plates in a single-cell per well format using a flow chamber cell sorter. Ten samples are selected from the expandable clones for the identification of differentiation and proliferation capabilities, while the remaining clones are cryopreserved.

Cell function identificationGENETIC

For single-cell samples of each patient, in vitro expansion culture is performed to observe the morphology of cells at each passage and calculate the clonogenic rate. Immunofluorescence technique is used to detect the expression of the cell proliferation marker Ki67, and the proliferation capacity is evaluated by combining with the CCK8 assay. Cells at passages P3-P5 are seeded on the permeable membrane of cell culture inserts at a density of \\(10\^6\\) cells/cm², and after 21 days of culture, the differentiated structures are collected. The expression of ciliated cell marker Ace-Tubulin and goblet cell marker MUC5AC is detected to assess the differentiation capacity. Meanwhile, cells are injected subcutaneously into NSG mice at \\(10\^6\\) cells/injection site for in vivo differentiation for 28 days, and the differentiated structures are collected for pathological analysis.

Identification of local microenvironmental changesGENETIC

The air-liquid interface (ALI) differentiation culture medium is collected, and cell debris is removed by high-speed centrifugation. The supernatant is then collected to extract proteins. Target proteins are purified via immunoprecipitation or affinity chromatography, followed by desalting and concentration for mass spectrometry analysis to detect inflammatory cytokines and extracellular matrix (ECM). Real-time PCR and Western blot techniques are used to measure the expression levels of epithelial markers, mesenchymal markers, and ECM in cells across all groups, thereby evaluating changes in the local microenvironment around small airways.

Gene editingGENETIC

After plasmid construction, based on gene function, the CRISPR-Cas9-sgRNA (all-in-one) plasmid is transiently transfected into expanded single-cell strains via Nucleofection to knockout the target gene, or the CRISPR-dCas9 fusion-sgRNA plasmid is transiently transfected to activate or inhibit the target gene. After 3-5 days of culture, viable cells are sorted by FACS, and single cells are seeded into 96-well plates for two additional passages of expansion. Samples are collected for Sanger sequencing to screen successfully constructed cell lines.

Prevention of ferret airway basal cell transplantationPROCEDURE

Before surgery, basal cells (BCs) of recipient ferrets are collected by bronchoscopic brushing, followed by in vitro culture and identification. Prior to the onset of BOS, the cells are injected into recipient ferrets via bronchoscopy. Outcomes including ferret survival rate, body weight, CT imaging, and lung tissue pathology are collected to evaluate the preventive effect of BCs on BOS.

Transplantation treatment of ferret airway basal cellsPROCEDURE

Stable cell lines with target gene knockdown are established in ferret basal cells (BCs). After ferrets develop bronchiolitis obliterans syndrome (BOS), the constructed cell lines are transplanted into recipient ferrets to validate the therapeutic effect of gene-corrected BCs on the disease.

Outcomes

Primary Outcomes

The self - renewal ability of airway basal cells

By comparing the Ki67 expression levels of airway basal cells and the results of the CCK8 assay in different samples (such as patients with bronchiolitis obliterans syndrome and healthy volunteers), clarify the abnormal manifestations of the self - renewal function of airway basal cells in the disease state, and further explore the internal connection between it and the occurrence and development of bronchiolitis obliterans syndrome.