Oxidative stress in neurological feline infectious peritonitis: cerebrospinal fluid 8-hydroxy-2"-deoxyguanosine and superoxide dismutase levels

Abstract

Oxidative stress plays a key role in the pathogenesis of neurological disorders and viral infections affecting the central nervous system. 8-Hydroxy-2"-deoxyguanosine (8-OHdG) is a marker of oxidative DNA damage, while superoxide dismutase (SOD) reflects antioxidant defense. This study aimed to evaluate SOD and 8-OHdG levels in the cerebrospinal fluid (CSF) of cats with neurological feline infectious peritonitis (FIP) to assess oxidative stress and antioxidant response. Twelve cats with neurological FIP and 10 age-matched control cats euthanized for non-neurological conditions were included. FIP diagnosis was confirmed by detecting feline coronavirus (FCoV) RNA in the CSF using real-time RT-PCR and by histopathological examination. CSF samples were analyzed for total protein, glucose, SOD, and 8-OHdG. Cats with FIP showed significantly higher CSF protein (740±230 mg/dL) than controls (17±7 mg/dL). The CSF/serum glucose ratio was lower in FIP cats (0.39±0.18) than in controls (0.66±0.06). 8-OHdG levels were elevated in FIP cats (6.88 ng/ml) compared to controls (1.09 ng/ ml; P<0.05). SOD levels were reduced in FIP cats (0.034±0.026 U/mg protein) versus controls (0.312±0.136 U/mg protein; P<0.001). These findings highlight a pronounced oxidative stress condition in neurological FIP, characterized by elevated 8-OHdG levels and reduced SOD concentrations in the CSF. This concurrent pattern may not only serve as a valuable biomarker of disease activity but also represent a potential therapeutic target for antioxidant-based strategies in affected cats.