Flow Cytometric Monitoring of the Redox Status in Health and Disease

Reactive oxygen and nitrogen species (ROS, RNS) play a pivotal role in cellular homeostasis and its functions, including immune responses. Excessive accumulation of free radicals disrupts the redox balance, leading to “oxidative stress” and oxidative damage to cellular components. Consequently, intricate regulation of both pro and antioxidant pathways is crucial to maintaining redox equilibrium. As oxidative stress is associated with disease advancement and drug efficacy, the redox status by flow cytometry is monitored using various fluorescent probes. These probes are employed to measure the generation of intracellular ROS, RNS, and superoxide as well as assess mitochondria-based factors (e.g., membrane polarization, transitional pore activity, etc.), damage markers, e.g., lipid peroxidation along with the antioxidant status (e.g., intracellular GSH, non-protein thiols etc.). Oxidative stress is associated with the pathogenesis of diseases like autoimmune (e.g., Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE, Vitiligo), Leishmaniasis, cancers, neurodegenerative disorders (e.g., Alzheimer’s disease, Parkinsonism), atherosclerosis etc. In autoimmune disorders, oxidative stress induces alterations in biomolecules (i.e., DNA, proteins, and lipids), resulting in the formation of neo-antigens that can trigger auto-antibody production and aid disease progression. Furthermore, redox imbalance can facilitate “inflammatory reprogramming” of neutrophils, evidenced by neutrophil-dendritic cell hybrids that further perpetuate disease progression. Allylpyrocatechol demonstrated its free radical scavenging potential, while malabaricone-A acted as a pro-oxidant and accelerated the generation of ROS, triggering apoptosis in cancer cell lines (solid tumors and leukemic). In summary, monitoring the redox status can serve as a biomarker for monitoring disease progression as well as for measuring therapeutic efficacy.