Evaluation of the mitochondrial dynamics in astrocytes and its impact on the inflammatory response in experimental autoimmune encephalomyelitis

Abstract

Multiple sclerosis is an autoimmune disease characterized by a chronic and progressive inflammatory condition in the Central Nervous System (CNS), which results in a process of axonal neurodegeneration, leading to neurological deficiency in patients. Currently there are several therapies that relieve the symptoms of the disease, however there is no cure available, especially when the neurodegenerative processes become more severe and of rapid progression. In addition, one of the issues that remains open in the area refers to the onset of inflammation in multiple sclerosis (MS), whether in the periphery or in the CNS itself. Recently, it has been established that astrocytes (glial cells) have a key role in regulating neuronal synapses and inflammatory processes in the CNS. According to this information, studies have shown that the deletion of the transcription factor NF-kappa B in astrocytes improves the symptoms of Experimental Autoimmune Encephalomyelitis (EAE), an animal model for MS studies, decreasing inflammation and recruitment of Immune cells to the inflamed region. It is also known that astrocytes are one of the largest sources of reactive oxygen species when subjected to inflammatory stimuli and this is directly related to the regulation of mitochondrial dynamics processes. Mitochondria constantly modify its morphology according to the bioenergetic needs of the cell and alterations in these mechanisms of regulation can participate in inflammatory and neurodegenerative processes. Thus, we formulate the hypothesis that alterations in the mitochondrial dynamics processes in astrocytes can directly interfere in the metabolic profile of these cells and in their pro or anti-inflammatory phenotype and this could impact EAE progression. Thus, the objective of this project is to analyze the impact of mitochondrial dynamics on astrocytes in the inflammatory, neurodegenerative, metabolic and oxidative stress responses in EAE. Initially, we will study the mitochondrial dynamics in vitro, focusing on astrocytes, evaluating the expression of proteins Mfn2 and Dnm1 as well as the production of reactive oxygen species in these cells in the face of stressful stimuli. Subsequently, we will use pharmacologic modulators of mitochondrial dynamics in the culture of primary astrocytes and study their reflex in cell metabolism and pro-or anti-inflammatory phenotype, observing the release of cytokines, expression of costimulatory and adhesion molecules. Finally, using mice with conditional knockout in the Mfn2 protein (related to the mitochondrial fusion process) in astrocytes (GFAPcre/Mfn2flox), we intend to demonstrate in vivo the relevance of mitochondrial dynamics in the pathogenesis of the disease, through the analysis of the inflammatory, neurodegenerative and oxidative stress processes in the CNS, as well as the infiltration of peripheral immune cells and an analysis of gene expression of astrocytes isolated from transgenic EAE mice. The preliminary results showed that there is a significant difference in expression of genes related to mitochondrial dynamics Mfn2 and Dnm1 in spinal cord cells and astrocytes between control and EAE mice and between isolated human PBMCs from healthy individuals and MS patients, thus pointing out to a role of these genes in the pathogenesis of the disease that should be better elucidated. (AU)