Photoprotective and genoprotective effects of theophylline against UVB-induced damage in normal human dermal fibroblasts.

BACKGROUND: Ultraviolet-B (UVB) radiation is a principal environmental factor driving cutaneous photoaging and carcinogenesis, primarily by inducing oxidative stress and DNA damage. This study investigated the potential of theophylline, a clinically established methylxanthine with known antioxidant and anti-inflammatory properties, to protect Normal Human Dermal Fibroblasts (NHDF) from UVB-induced genotoxic stress. METHODS: NHDF cultures were pre-treated for 24 h with theophylline at concentrations of 10–200 micromolar (µM) and subsequently exposed to UVB irradiation (100 mJ/cm²). A comprehensive panel of cellular assays was employed to evaluate cytotoxicity (MTT, LDH, ATP, caspase-3/7 assays), oxidative stress (ROS, MDA, GSH/GSSG ratio, SOD, catalase activity), genotoxicity (Comet and micronucleus assays), mitochondrial function (MMP, NAD⁺/NADH ratio), inflammatory responses (IL-6, IL-8, TNF-α, IL-1β), and apoptosis (TUNEL assay). RESULTS: UVB irradiation induced marked cytotoxicity, oxidative stress, mitochondrial dysfunction, and significant DNA damage in NHDF cells. Theophylline pre-treatment significantly attenuated these deleterious effects in a concentration-dependent manner. Specifically, theophylline restored cell viability, preserved mitochondrial function, reduced ROS generation and lipid peroxidation, enhanced endogenous antioxidant defenses, suppressed the release of pro-inflammatory cytokines, and inhibited DNA damage and apoptosis. CONCLUSION: The results demonstrate that theophylline confers broad cytoprotective and genoprotective effects against UVB-mediated toxicity in human dermal fibroblasts. By mitigating oxidative stress, stabilizing mitochondrial function, suppressing inflammation, and preventing apoptosis, theophylline shows significant promise as a novel photoprotective agent for mitigating solar-induced skin damage and preventing UVB-mediated genomic instability.