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Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Microglia play a crucial role in a range of neuropathologies through exacerbated activation. Microglial inflammatory responses can be influenced by prior exposures to noxious stimuli, like increased levels of extracellular adenosine and ATP. These are characteristic of brain insults like epileptic seizures and could potentially shape subsequent responses through epigenetic regulation. We investigated DNA methylation and expression changes in human microglia-like cells differentiated from monocytes following ATP-mediated preconditioning. We demonstrate that microglia-like cells display homeostatic microglial features, shown by surface markers, transcriptome, and DNA methylome. After exposure to ATP, TLR-mediated activation leads to an exacerbated pro-inflammatory response. These changes are accompanied by methylation and transcriptional reprogramming associated with enhanced immune-related functions. The reprogramming associated with ATP-mediated preconditioning leads to profiles found in microglial subsets linked to epilepsy. Purine-driven microglia immune preconditioning drives epigenetic and transcriptional changes that could contribute to altered functions of microglia during seizure development and progression., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s).)

Multiple sclerosis (MS) is a chronic neuroinflammatory autoimmune disease believed to arise from complex interactions of both environmental and genetic factors. As in other complex diseases with autoimmune features, a genetic association with the human leukocyte antigen (HLA) complex is well documented. Association and genome-wide studies were performed in Portuguese patients with MS over several years. Genes such as HLA-DRB1, HLA-A, HFE, TNFA, CTLA-4, PTPN22 and ApoE were investigated. ApoE, PTPN22 1858T, CTLA-4 -318C, TNFA-308A, HFE C282Y and TLR9 T-1237C polymorphisms were not shown to be associated with the development of MS. The HLA-DRB1*15 allele was confirmed as the major genetic marker for susceptibility to MS. The presence of HLA-A*02 and TNFA -238A alleles decreased the risk of developing MS. Patients carrying the HFE C282Y variant seem to have a worse prognosis. The HLA-DRB1*15 and PTPN22 1858T variants were associated with a better outcome in this population.