Modulation of Autophagic Flux by Tibolone in Models of Neuroinflammation

Tibolone, a synthetic steroid, has shown neuroprotective effects in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis (MS). In this study, we investigated the impact of tibolone on microglial activation and autophagy using in vitro and in vivo models relevant to MS. In vitro, BV-2 microglia cells were pre-treated with tibolone and stimulated with lipopolysaccharide (LPS), with or without lysosomal inhibitors to block autophagic flux. In vivo, the expression of autophagic markers was evaluated in the spinal cord of EAE mice treated with tibolone. LPS stimulation significantly elevated IL-1β and NLRP3 expression, whereas tibolone pre-treatment effectively prevented these increases. Furthermore, tibolone attenuated NF-κB nuclear translocation and mitochondrial ROS production. Notably, these anti-inflammatory and antioxidant effects were autophagy-dependent, as they were lost upon co-treatment with lysosomal inhibitors. While the autophagosome marker LC3 increased in microglia exposed to LPS, tibolone normalized LC3 levels without blocking autophagic flux. In EAE mice, tibolone administration successfully restored disease-associated alterations of Beclin-1 and p62 in the spinal cord. Collectively, these findings indicate that tibolone exerts pleiotropic anti-inflammatory and antioxidant effects in microglia while normalizing compensatory autophagy, supporting its therapeutic potential for MS treatment.