COMPARATIVE PROTEIN KINASE C MODULATION BY PROSTRATIN AND BRYOSTATIN-1 ON MICROGLIAL ACTIVATION AND NEURITE OUTGROWTH IN <EM>IN VITRO</EM> MODELS OF SPINAL CORD INJURY

Protein Kinase C (PKC) signaling regulates neuroinflammation, neuroimmune interactions, and neuronal plasticity following central nervous system (CNS) diseases and injuries. Non-tumor-promoting PKC modulators such as Prostratin and Bryostatin (Bryo-1) provide an opportunity to target these pathways.
Here, we investigated how PKC modulation shapes microglial activation states and neuronal stress responses and compared the potency of Prostratin and Bryo-1 across multiple in vitro CNS models and evaluated the translational potential of Bryo-1 in a spinal cord injury (SCI) rodent model. Prostratin and Bryo-1 were tested in BV-2 microglia as well as primary microglial, glial, and neuronal cultures under physiological and inflammatory conditions. PKC dependency was validated using pharmacological inhibition. We assessed PKC kinase activity, NF-_kB signaling, microglial morphology, phagocytosis, inflammatory marker expression and neurite extension. Both compounds were non-cytotoxic and induced a distinct PKC-dependent microglial phenotype characterized by enhanced phagocytosis and reduced pro-inflammatory signaling. In neuronal cultures, PKC modulation reduced metabolic stress, apoptotic signaling and supported neurite outgrowth under hypoxia-mimicking conditions. Bryo-1 was effective at nanomolar concentrations and showed greater potency than Prostratin. Based on this profile, Bryo-1 was selected for current in vivo testing to assess its activity during the acute phase after SCI. Selective PKC modulation shapes microglial activation states and enhances neuronal resilience.
Together, these findings identify PKC modulators such as Bryo-1 as a promising and translatable strategy to regulate neuroimmune responses towards a regenerative phenotype while reducing inflammatory signaling. This supports Bryo-1 as a compelling candidate to enhance neuronal resilience following CNS injury.