Loss of AMPK potentiates inflammation by activating the inflammasome after traumatic brain injury in mice.

ABSTRACT

Traumatic brain injury (TBI) is a significant public health concern characterized by a complex cascade of cellular events. TBI induces adenosine monophosphate-activated protein kinase (AMPK) dysfunction impairs energy balance activates inflammatory cytokines and leads to neuronal damage. AMPK is a key regulator of cellular energy homeostasis during inflammatory responses. Recent research has revealed its key role in modulating the inflammatory process in TBI. Following TBI the activation of AMPK can influence various important pathways and mechanisms including metabolic pathways and inflammatory signaling. Our study investigated the effects of post-TBI loss of AMPK function on functional outcomes inflammasome activation, and inflammatory cytokine production. Male C57BL/6 adult wild-type (WT) and AMPK knockout (AMPK-KO) mice were subjected to a controlled cortical impact (CCI) model of TBI or sham surgery. The mice were tested for behavioral impairment at 24 h post-TBI thereafter, mice were anesthetized, and their brains were quickly removed for histological and biochemical evaluation. In vitro we investigated inflammasome activation in mixed glial cells stimulated with lipopolysaccharides+ Interferon-gamma (LI) (0.1 µg/20 ng/ml LPS/IFNg) for 6 h to induce an inflammatory response. Estimating the nucleotide-binding domain, leucine-rich-containing family pyrin domain containing western blotting ELISA and qRT-PCR performed 3 (NLRP3) inflammasome activation and cytokine production. Our findings suggest that TBI leads to reduced AMPK phosphorylation in WT mice and that the loss of AMPK correlates with worsened behavioral deficits at 24 h post-TBI in AMPK-KO mice as compared to WT mice. Moreover compared with the WT mice AMPK-KO mice exhibit exacerbated NLRP3 inflammasome activation and increased expression of proinflammatory mediators such as IL-1b IL-6 TNF-a iNOS and Cox 2. These results align with the in vitro studies using brain glial cells under inflammatory conditions, demonstrating greater activation of inflammasome components in AMPK-KO mice than in WT mice. Our results highlighted the critical role of AMPK in TBI outcomes. We found that the absence of AMPK worsens behavioral deficits and heightens inflammasome-mediated inflammation thereby exacerbating brain injury after TBI. Restoring AMPK activity after TBI could be a promising therapeutic approach for alleviating TBI-related damage.