A novel fluorescent probe for the in-situ visualization of superoxide anions during pulmonary fibrosis

Abstract

Pulmonary fibrosis (PF) is a progressive and refractory lung disease characterized by fibrosis that can result in the accumulation of extracellular matrix, impair alveolar elasticity, and consequently increase mortality. Superoxide anion (O₂^•−), as one of the initial intracellular reactive oxygen species, plays a pivotal role in cell signaling networks and redox homeostasis. Abnormal levels of this species can directly reflect the state of intracellular oxidative stress. Nevertheless, the relationship between O₂^•− and PF has remained unclear. Accordingly, a fluorescent probe, designated SOACHO, was devised and constructed for the purpose of detecting O₂^•−. The fluorescence emission peak of SOACHO in response to O₂^•− was observed to occur at a wavelength of 627 nm. The SOACHO demonstrated high specificity and sensitivity to O₂^•−, with a response time of less than 300 seconds and a detection limit of 12 nM. SOACHO was capable of specifically detecting the endogenous O₂^•− levels in cells without interference from nucleophilic reagents and oxidants, and subsequently monitoring the levels of O₂^•− in oxidative stress and pulmonary fibrosis cell models. Furthermore, SOACHO was able to monitor the levels of O₂^•− in the lungs of mice in real-time, providing insights into the progression of pulmonary fibrosis. The severity of pulmonary fibrosis was found to be positively correlated with O₂^•−, as evidenced by the correlation with hydroxyproline content, lung coefficients, histopathological observations, and immunohistochemical analyses. The aforementioned results may offer a novel perspective on the early treatment of pulmonary fibrosis.