Abstract Details

Title Impaired Oxidative DNA Lesions Repair Kinetics in Multiple Sclerosis: Combined Assessment of Functional Capacity, Gene Expression, and Genetic Variants in the Base Excision Repair Pathway

Topic Multiple Sclerosis

Presentation(s) P2 - Poster Session 2 (11:45 AM-12:45 PM)

Poster/Presentation
Number 18-002

Objective

We sought to determine whether compromised base excision repair (BER) mechanisms contribute to MS development by simultaneously examining repair function, transcript abundance, and polymorphic variation.

Background

Neuroinflammatory processes in MS generate reactive oxygen species that inflict substantial DNA damage. Cellular responses to oxidative damage depend heavily on BER, which removes modified bases and restores genomic integrity. Deficiencies in BER could permit the accumulation of mutagenic lesions, potentially accelerating neurodegeneration, yet functional impact of BER in MS remains poorly characterized.

Design/Methods We isolated PBMCs from 70 MS patients and 61 controls, challenged them with 7µM tert-butylhydroperoxide, and tracked DNA damage resolution over 60minutes using alkaline single-cell gel electrophoresis. Transcript levels for nine BER components (OGG1, MBD4, APEX1, APEX2, PARP1, PARP2, LIG3, NTHL1, MUTYH) were measured via real-time PCR with dual housekeeping normalization. For genotyping SNPs we used real-time PCR. To assess cell-specific responses, we purified B lymphocytes, CD4?helper cells, and CD8?cytotoxic cells and repeated kinetic measurements in each subset.

Results Following oxidative challenge, MS-derived cells displayed a substantially greater lesion burden than controls (p<0.001). Longitudinal analysis demonstrated that while control cells restored baseline integrity within 1 hour, MS cells exhibited persistent damage (group effect:F=41.61, p<0.0001; group×time:F=12.49, p<0.0001). At the transcriptional level, MBD4 and NTHL1 expression was reduced in MS (both p<0.0001). Regression modeling identified three SNPs conferring altered repair phenotypes:rs3087404(SMUG1), rs4135054(TDG), and rs1052133(OGG1) showed independent associations with MS after covariate adjustment. All three purified lymphocyte lineages exhibited abnormal repair trajectories in MS (B cells:F=3.93, p=0.006; CD4?:F=6.27, p<0.001; CD8?:F=5.73, p=0.0002), though initial damage levels were comparable in specific subsets.

Conclusions

We present converging evidence that MS involves systemic BER dysfunction, showed by slower lesion resolution, diminished glycosylase expression, and risk-associated genetic architecture. Future investigations should establish whether restoring BER capacity can modify disease trajectory and whether genotype-directed interventions offer superior outcomes in carriers of high-risk alleles.

Authors/Disclosures
Beata A. Filipek, MD, PhD (International Doctoral School Medical University of Lodz) PRESENTER	Dr. Filipek has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche. The institution of Dr. Filipek has received research support from National Centre of Science, Poland - Preludium Bis 2019/35/O/NZ5/02270.
Anna Macieja, PhD	Ms. Macieja has nothing to disclose.
Aleksandra J. Binda	Ms. Binda has nothing to disclose.
Ryan Miller	Mr. Miller has received personal compensation for serving as an employee of Resonant. Mr. Miller has stock in Inherent Biosciences. Mr. Miller has received intellectual property interests from a discovery or technology relating to health care.
Mariola Swiderek-Matysiak	Mariola Swiderek-Matysiak has nothing to disclose.
Mariusz Stasiolek, MD	Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Merck. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for AstraZeneca. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Novartis. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Roche. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Biogen. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Bristol Myers Squibb. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for AstraZeneca. Dr. Stasiolek has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Merck.
Ireneusz Majsterek, PhD	Prof. Majsterek has nothing to disclose.
Tomasz Poplawski	Tomasz Poplawski has nothing to disclose.

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