Biology subjects

Chitnis, T.

Publications and source records attributed to Chitnis, T..

5 recordsLinked to original sources

bioRxiv2026

Metabolomics reveals lipid and amino acid signatures of disease severity in multiple sclerosis

ObjectivePlasma metabolomics offers insight into multiple sclerosis (MS) pathophysiology, but existing studies are limited by small sample sizes and incomplete clinical data. MethodsWe conducted plasma metabolomic profiling of 411 deeply phenotyped patients with MS and 46,443 controls, analyzing 162 metabolites in 30 biologically related metabolite groups. We characterized associations with MS diagnosis, disability, disease subtype, and inflammatory disease activity using regression and differential network enrichment analysis. We additionally examined 25 pre-diagnosis individuals whose samples were collected before their first demyelinating event. ResultsFourteen of 30 metabolite groups were associated with MS after false discovery rate correction, with the strongest positive associations observed for atherogenic lipoproteins, glycine, cholines, and saturated fatty acids, and the strongest negative associations for aromatic amino acids, branched-chain amino acids, alanine, and citrate. Differential network enrichment analysis identified two dysregulated subnetworks encompassing amino acid and energy metabolism and lipid and lipoprotein metabolism. Five metabolite groups were negatively associated with disability: small high-density lipoprotein particles, histidine, branched-chain amino acids, albumin, and aromatic amino acids. The omega-6/omega-3 fatty acid ratio was significantly associated with recent relapse (OR = 1.92, FDR-p = 0.030) and nominally associated with future MRI activity, especially in patients on moderate or high-efficacy disease-modifying therapy. The MS metabolic signature was not detectable in pre-diagnosis samples. InterpretationThese findings highlight coordinated dysregulation of amino acid and lipoprotein metabolism as hallmarks of established MS and identify a novel association of the omega-6/omega-3 ratio with inflammatory disease activity.

neuroscience↗

bioRxiv2025

ODC1 restricts meningeal B cell age-associated-like phenotype and function in multiple sclerosis: a human and experimental study

Meningeal inflammation, as a clinical feature of multiple sclerosis (MS), is associated with worse clinical disease outcomes. In both relapsing and secondary progressive MS and the experimental autoimmune encephalomyelitis (EAE) MS model, the meninges have been found to contain ectopic lymphoid follicles enriched with B cells. The metabolic requirement of meningeal B cell function in MS or EAE is not well elucidated. Using 7-Tesla MRI brain scans of MS patients and leptomeningeal enhancement (LME) as a marker, we found a correlation between meningeal inflammation and metabolites of the arginine/polyamine pathway, a finding recapitulated in the EAE model. Ornithine Decarboxylase (ODC1), the rate limiting enzyme for polyamine biosynthesis, as well as polyamine metabolism was diminished in the dura meningeal B cells from mice with MOG35-55 induced EAE mice as compared to naive controls. Pharmacological inhibition of ODC1 restricted meningeal T cells but promoted meningeal B cell proliferation. B cell-specific deletion of ODC1 resulted in expansion of B cells with age-associated B cell-like phenotype (CD11c+CD21/35-CD23-IgD-) and exacerbated disease in the MOG1-125 EAE model. Together, these findings demonstrate a divergent role of polyamines in regulating B and T cell responses in the meninges during autoimmunity. Significance StatementThis study identified the polyamine pathway to be associated with meningeal inflammation in multiple sclerosis, a clinical phenotype associated with worse disease outcomes and without targeted therapy. Using a mouse experimental model, we found that ODC1, the rate limiting enzyme of the polyamine biosynthesis pathway, was suppressed in meningeal B cells, restricted the development of age-associated B cells in the meninges and limited disease severity. This study elucidated a metabolic pathway regulating meningeal B cell function, informing its therapeutic applications in autoimmune diseases.

immunology↗

bioRxiv2025

Sex differences in progressive multiple sclerosis brain gene expression in oligodendrocytes and OPCs

Multiple sclerosis is a neurological autoimmune disease with sex-imbalanced incidence; in the USA, the disease is more likely to effect females at a ratio of 3:1. In addition, males are more likely to have a more severe disease course at time of diagnosis. Questions about both causes and downstream effects of this disparity remain. We aim to investigate gene expression differences at a cellular level while considering sex to discover fine-scale sex disparities. These investigations could provide new avenues for treatment targeting, or treatment planning based on sex. Public single-nuclei RNA-sequencing data from three publications of progressive MS including control brains were analysed using the Seurat R package. Differential gene and pathway expression was looked at both within a specific data set which has sub-lesion level sample dissection and across all studies to provide a broader lens. This allowed for the consideration of cell types and spatial positioning in relation to the interrogated lesion in some of the calculations. Our analysis showed expression changes in the female MS oligodendrocytes and oligodendrocyte progenitor cells compared to healthy controls, which were not observed in the corresponding male affected cells. Differentially up-regulated genes in females include increased HLA-A in the oligodendrocytes, and increased clusterin in the oligodendrocyte progenitor cells. There are also several mitochondrial genes in both the oligodendrocytes and oligodendrocyte progenitors which are up-regulated in females, including several directly involved in electron transport and which have previously been associated with neurodegenerative diseases. These results point to altered states in oligodendrocyte progenitors and oligodendrocytes that in combination with known physiological dissimilarities between sexes may denote different programming in males and females in response to the onset of demyelinating lesions. The potential for increased debris clearance mediated by clusterin and availability of oligodendrocyte progenitors in females may indicate an environment more primed for repair, potentially including remyelination. This could contribute to the disparity in etiology in females versus males.

neuroscience↗

bioRxiv2021

Dissection of multiple sclerosis genetics identifies B and CD4 T cells as driver cell subsets

Multiple sclerosis (MS) is an autoimmune condition of the central nervous system with a well-characterized genetic background. Prior analyses of MS genetics have identified broad enrichments across peripheral immune cells, yet the driver immune subsets are unclear. We utilized chromatin accessibility data across hematopoietic cells to identify cell type-specific enrichments of MS genetic signals. We found that CD4 T and B cells were independently enriched for MS genetics and further refined the driver subsets to Th17 and memory B cells, respectively. We replicated our findings in data from untreated and treated MS patients and found that immunomodulatory treatments suppress chromatin accessibility at driver cell types. Integration of statistical fine-mapping and chromatin interactions nominated numerous putative causal genes, illustrating complex interplay between shared and cell-specific genes. Our study highlights how careful integration of genetics and epigenetics can provide fine-scale insights into causal cell types and nominate new genes and pathways for disease.

genetics↗

bioRxiv2019

Serological and metagenomic interrogation of cerebrospinal fluid implicates enteroviruses in pediatric acute flaccid myelitis

BackgroundSince 2014, the United States has experienced a biennial spike in pediatric acute flaccid myelitis (AFM). Epidemiologic evidence suggests non-polio enteroviruses (EVs) are a potential etiology, yet EV RNA is rarely detected in cerebrospinal fluid (CSF) and only inconsistently identified from the respiratory tract, serum, or stool.\n\nMethodsWe interrogated CSF from children with AFM (n=42) and pediatric controls with other neurologic diseases (OND) (n=58). Samples were incubated with T7 bacteriophage expressing 481,966 sixty-two amino acid peptides with a fourteen amino acid overlap tiled across all known vertebrate virus and arbovirus genomes, an adaption of the VirScan method. Antibody-bound phage were deep sequenced to quantify enriched peptides with normalized counts expressed as reads per hundred thousand (rpK). EV antibody findings were confirmed with ELISA using whole viral protein 1 (VP1) from contemporary enterovirus (EV) A71 and D68 strains. Separately, metagenomic next-generation sequencing (mNGS) of CSF RNA, both unbiased and with targeted enrichment for EVs, was performed.\n\nResultsThe most significantly enriched viral family by VirScan of CSF in AFM versus OND controls was Picornaviridae (mean rpK 11,266 versus mean rpK 950, p-adjusted < 0.001, Wilcoxon signed-rank test with Bonferroni adjustment). Enriched Picornaviridae peptides belonged almost entirely to the genus Enterovirus. The mean EV VP1 ELISA signal in AFM (mean OD 0.51) was significantly higher than OND controls (mean OD 0.08, p-value < 0.001, Mann-Whitney test). mNGS did not detect additional enterovirus RNA in CSF.\n\nConclusionDespite the rare detection of EV RNA in the CNS of patients with AFM, a pan-viral serologic assay identified high levels of CSF EV antibodies in AFM CSF compared to CSF from OND controls. These results provide further evidence for a causal role of non-polio enteroviruses in AFM.

microbiology↗