Suhail, Hamid

Abstract Multiple sclerosis is a chronic inflammatory and demyelinating disease of the CNS. Although, MS is well characterized in terms of the role played by immune cells, cytokines and CNS pathology, nothing is known about the metabolic alterations that occur during the disease process in circulation. Here, we profiled the plasma metabolites of B6 with EAE, a known model of chronic MS using untargeted global metabolomics. Using a combination of high-throughput liquid-and-gas chromatography with mass spectrometry, a total of 326 metabolites were identified, with significant changes observed in 105 metabolites (13 up- and 92 down-regulated), that mapped to lipid and amino acid pathways, followed by the peptide, xenobiotic, carbohydrate, nucleotide and energy pathways (p<0.05). To understand the functional role of these alterations, the KEGG metabolic library was analyzed using Metaboanalyst. The top nine most significant pathways in terms of GlobeTest p-value and impact are 1) fatty acid biosynthesis, 2) lysine degradation, 3) histidine metabolism, 4) beta-alanine metabolism, 5) pentose phosphate pathway, 6) arachidonic acid metabolism, 7) linoleic acid, 8) D-arginine and ornithine. Overall, these metabolic changes could be exploited as biomarkers for EAE/MS disease and to design new treatment paradigms where metabolic interventions could be combined with present and experimental therapeutics to achieve better treatment.

Abstract In search of metabolites signature as biomarkers during EAE disease, we profiled urine from B6 EAE using global untargeted metabolomics. Evaluation of metabolomic profiling of urine from EAE and healthy B6 group by using a combination of high-throughput liquid-and-gas chromatography with mass spectrometry, we found that 132 out of 322 (41%) metabolites were differentially altered (P<0.05) indicating robust alteration in the urine metabolomics profile during disease. Among the perturbed metabolites, 11 were up regulated in EAE urine whereas 121 were down regulated. We conducted pathway analysis of the biochemical pathways of the KEGG and considered both concerted changes in metabolite intensity within the pathway (GlobalTest) and alterations of high impact, and found that a number of pathways were significantly altered including glyoxylate and dicarboxylate, phenylanine metabolism, porphyrin & chlorophyll metabolism, primary bile acid biosynthesis, cysteine & methione metabolism, taurine and hypotaurine metabolism, glycine, serine & threonine metabolism, and beta-alanine metabolism. Alteration in these pathways during EAE disease suggesting that perturbation of certain central metabolites could have impact on multiple metabolic pathways. While some of these metabolite changes could easily be developed as biomarkers, the key to translating metabolomics into therapeutics would require figuring out the central altered metabolic pathway(s), once studied in detail.

Abstract The AMP-activated protein kinase, AMPK, is an energy-sensing, metabolic switch implicated in various metabolic disorders; however, its role in inflammation is not well defined. We have previously shown that loss of AMPK exacerbates experimental autoimmune encephalomyelitis (EAE) disease severity. In this study, we investigated the mechanism through which AMPK modulates inflammatory disease like EAE. AMPKα1 knockout (α1KO) mice with EAE showed severe demyelination and inflammation in the brain and spinal cord compared with wild-type due to higher expression of proinflammatory Th17 cytokines, including IL-17, IL-23, and IL-1β, impaired blood–brain barrier integrity, and increased infiltration of inflammatory cells in the CNS. Infiltrated CD4 cells in the brains and spinal cords of α1KO with EAE were significantly higher compared with wild-type EAE and were characterized as IL-17 (IL-17 and GM-CSF double-positive) CD4 cells. Increased inflammatory response in α1KO mice was due to polarization of macrophages (Mϕ) to proinflammatory M1 type phenotype (IL-10lowIL-23/IL-1β/IL-6high), and these M1 Mϕ showed stronger capacity to induce allogenic as well as Ag-specific (myelin oligodendrocyte glycoprotein [MOG]35–55) T cell response. Mϕ from α1KO mice also enhanced the encephalitogenic property of MOG35–55–primed CD4 T cells in B6 mice. The increased encephalitogenic MOG-restricted CD4+ T cells were due to an autocrine effect of IL-1β/IL-23–mediated induction of IL-6 production in α1KO Mϕ, which in turn induce IL-17 and GM-CSF production in CD4 cells. Collectively, our data indicate that AMPK controls the inflammatory disease by regulating the M1 phenotype–Th17 axis in an animal model of multiple sclerosis.