A two-photon fluorescent probe for imaging of mitochondrial cysteine in λ-carrageenan induced arthritis

Arthritis is an inflammatory and autoimmune disease seriously affecting the quality of a patient’s life, and its pathogenesis remains obscure. Mitochondrial oxidative stress is involved in the patho-physiology of arthritis. Cystein (Cys) plays a crucial role as a free radical scavenger in oxidative stress, and thus decreased mitochondrial Cys might be observed in mice with arthritis. To verify this inference, we report a two-photon imaging probe for fluorescence measurement of mitochondrial Cys with high selectivity and good sensitivity. InCYS can track Cys in situ through one-photon and two-photon fluorescence imaging in vivo. By using InCYS, we successfully revealed decreases in the levels of mitochondrial Cys in the ankles of mice with arthritis. This work provides an effective bio-target for the development of novel therapeutic approaches for arthritis, and a practical tool for revealing the connections between mitochondrial oxidative stress and severe diseases.