Fluorescence And Photoacoustic Imaging Analysis Of Cysteine And Nitric Oxide In Pulmonary Fibrosis

Pulmonary fibrosis(PF)is a progressive and fatal interstitial lung disease.Its main pathological features are increased fibroblast proliferation,amplified levels of extracellular matrix deposition,accompanied by the destruction and loss of tissue structure and function due to inflammatory injury,which eventually leads to respiratory failure and death.The median survival of patients is from 3 to 5 years from the time of diagnosis.At present,because the pathogenesis of pulmonary fibrosis is not clear,specific early diagnosis and effective treatment methods are still lacking.In recent years,with the increasing incidence of pulmonary fibrosis,many studies on pulmonary fibrosis have been reported.Current studies report that the concentration of glutathione(GSH)is relatively low in the lungs of patients with pulmonary fibrosis than healthy people.However,it is still unclear whether this phenomenon is caused by an extremely low level of GSH synthesis precursor –cysteine(Cys)or abnormal activity of related enzymes.Therefore,there is an urgent need to develop a new tool for in situ detection of Cys content in pulmonary fibrosis patients,and then to reveal the mechanism of GSH synthesis restriction during pulmonary fibrosis.In addition,studies have shown that the existence of angiogenesis in pulmonary fibrosis,and the neovascularization enhances fibrosis,with evidence for involvement of abnormal repair and aberrant vascular remodeling associated with angiogenesis in both animal models and tissue specimens from patients.Nevertheless,the specific mechanistic details underlying angiogenic modulation in pulmonary fibrosis remain unclear.Several reports have implicated nitric oxide(NO)in various physiological processes,including angiogenesis in a manner consistent with a pro-angiogenic phenotype.Therefore,it is expected to provide a potential tool to investigate the role of angiogenesis in the pathogenesis of pulmonary fibrosis by analyzing the concentration of NO in the process of pulmonary fibrosis.The main contents of this thesis are outlined as follows.1.We developed a novel photoacoustic and fluorescent dual-mode probe,CCYS,that responds to Cys with high selectivity and sensitivity for the first time.CCYS was composed of an NIR fluorescent dye,hemicyanine(Cy-OH),as a chromophore and an acrylate functional group as a recognition site.The probe was successfully applied for monitoring the Cys level in the process of pulmonary fibrosis both in tissues and in vivo.The results clarify that the concentration of Cys is abundant in the process of pulmonary fibrosis,which is not the critical factor that causes the limited synthesis rate of GSH.Moreover,This work provides a potent tool to distinguish pulmonary fibrosis from pneumonia in the clinic and offers a potential target for the discovery of new drugs for pulmonary fibrosis.2.Based on the specific recognition reaction between o-phenylenediamine and nitric oxide,and photoinduced electron transfer(PET),we designed and synthesized a two-photon fluorescent probe(TCO-TP)for detecting NO.The probe TCO-TP is composed of a 3-carboxyl-7-hydroxycoumarin as a chromophore and an o-phenylenediamine functional group as a recognition site.TCO-TP can linearly change the fluorescence intensity with the concentration of NO,and is used for highly selective detection of NO in cells and living bodies.