Biomedical subjects

Tanuja Chitnis

Publications and source records attributed to Tanuja Chitnis.

4 recordsLinked to original sources

PubMed2026

EBV reactivation priming of the peripheral immune system in multiple sclerosis relapse.

Despite decades of research, the cellular and molecular events preceding multiple sclerosis (MS) relapse remain incompletely understood. Here, in this observational study of longitudinal blood samples from patients with relapsing-remitting MS, we used single-cell RNA sequencing, bulk transcriptomics, multiparameter flow cytometry and targeted viral reverse transcription quantitative polymerase chain reaction (RT-qPCR) to construct a time-resolved atlas of immune perturbations surrounding relapse. A reproducible pre-relapse signature in monocytes and B cells, emerging up to 3 months before clinical onset, was enriched for host genes responsive to Epstein-Barr virus (EBV) lytic reactivation factors. RT-qPCR confirmed elevated EBV LMP-1 transcripts in pre-relapse B cells, and flow cytometry demonstrated expansion of CD11c+ atypical B cell populations displaying EBV surface protein gp350. Pre-relapse transcriptional modules overlapped with MS genome-wide association study (GWAS) risk loci and EBNA-2-bound enhancers, suggesting that inherited MS susceptibility and EBV-responsive programs operate through shared regulatory elements. How this peripheral activation relates to central nervous system lesion formation remains to be established. These findings nonetheless suggest that EBV reactivation, when occurring within a genetically predisposed peripheral immune environment, is a proximal precursor of MS relapse.

Journal Article↗

PubMed2026

Genome-wide association analyses highlight the neuronal contribution to multiple sclerosis susceptibility.

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease. Previous genetic studies have identified susceptibility loci that primarily impact immune cells and microglia. Here we performed a multi-ancestry genome-wide association study of 20,831 MS cases and 729,220 controls and identified 236 susceptibility variants outside of the major histocompatibility complex, including four novel genomic loci. We also derived a polygenic score for MS; while optimized for European ancestry, it is informative for African American and Latino individuals. Integrating single-cell data from blood and brain tissue, we identified 76 candidate causal genes. Inhibitory neurons emerged as a key target cell type for MS-associated variants, with seven loci, including STAT3, displaying altered expression only in these cells. The STAT3 variant is also associated with cognition and white matter integrity in individuals with no MS and greater sNfL levels in individuals with MS, suggesting that MS susceptibility may reflect reduced central nervous system resilience to inflammatory challenges.

Humans↗

PubMed2025

GWAS highlights the neuronal contribution to multiple sclerosis susceptibility.

Multiple Sclerosis (MS) is a chronic inflammatory and neurodegenerative disease affecting the brain and spinal cord. Genetic studies have identified many risk loci, that were thought to primarily impact immune cells and microglia. Here, we performed a multi-ancestry genome-wide association study with 20,831 MS and 729,220 control participants, identifying 236 susceptibility variants outside the Major Histocompatibility Complex, including four novel loci. We derived a polygenic score for MS and, optimized for European ancestry, it is informative for African-American and Latino participants. Integrating single-cell data from blood and brain tissue, we identified 76 genes affected by MS risk variants. Notably, while T cells showed the strongest enrichment, inhibitory neurons emerged as a key cell type. The expression of IL7 and STAT3 are affected only in inhibitory neurons, highlighting the importance of neuronal and glial dysfunction in MS susceptibility.

Journal Article↗

PubMed2023

Rare and low-frequency coding genetic variants contribute to pediatric-onset multiple sclerosis.

BACKGROUND: Rare genetic variants are emerging as important contributors to the heritability of multiple sclerosis (MS). Whether rare variants also contribute to pediatric-onset multiple sclerosis (POMS) is unknown. OBJECTIVE: To test whether genes harboring rare variants associated with adult-onset MS risk (PRF1, PRKRA, NLRP8, and HDAC7) and 52 major histocompatibility complex (MHC) genes are associated with POMS. METHODS: We analyzed DNA samples from 330 POMS cases and 306 controls from the US Network of Pediatric MS Centers and Kaiser Permanente Northern California for which Illumina ExomeChip genotypes were available. Using the gene-based method "SKAT-O," we tested the association between candidate genes and POMS risk. RESULTS: After correction for multiple comparisons, one adult-onset MS gene (PRF1, p = 2.70 × 10-3) and two MHC genes (BRD2, p = 5.89 × 10-5 and AGER, p = 7.96 × 10-5) were significantly associated with POMS. Results suggest these are independent of HLA-DRB1*1501. CONCLUSION: Findings support a role for rare coding variants in POMS susceptibility. In particular, rare minor alleles within PRF1 were more common among individuals with POMS compared to controls while the opposite was true for rare variants within significant MHC genes, BRD2 and AGER. These genes would not have been identified by common variant studies, emphasizing the merits of investigating rare genetic variation in complex diseases.

Child↗