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Amelioration of Autoimmune Arthritis in Mice Treated With the DNA Methyltransferase Inhibitor 5'-Azacytidine
Dániel M Tóth1, Timea Ocskó1, Attila Balog2
1Rush University Medical Center, Chicago, Illinois.
Objective:
Disease-associated, differentially hypermethylated regions have been reported in rheumatoid arthritis (RA), but no DNA methyltransferase inhibitors have been evaluated in either RA or any animal models of RA. The present study was conducted to evaluate the therapeutic potential of 5'-azacytidine (5'-azaC), a DNA methyltransferase inhibitor, and explore the cellular and gene regulatory networks involved in the context of autoimmune arthritis.
Methods:
A disease-associated genome-wide DNA methylation profile was explored by methylated CpG island recovery assay-chromatin immunoprecipitation (ChIP) in arthritic B cells. Mice with proteoglycan-induced arthritis (PGIA) were treated with 5'-azaC. The effect of 5'-azaC on the pathogenesis of PGIA was explored by measuring serum IgM and IgG1 antibody levels using enzyme-linked immunosorbent assay, investigating the efficiency of class-switch recombination (CSR) and Aicda gene expression using real-time quantitative polymerase chain reaction, monitoring germinal center (GC) formation by immunohistochemistry, and determining alterations in B cell subpopulations by flow cytometry. The 5'-azaC-induced regulation of the Aicda gene was explored using RNA interference, ChIP, and luciferase assays.
Results:
We explored arthritis-associated hypermethylated regions in mouse B cells and demonstrated that DNA demethylation had a beneficial effect on autoimmune arthritis. The 5'-azaC-mediated demethylation of the epigenetically inactivated Ahr gene resulted in suppressed expression of the Aicda gene, reduced CSR, and compromised GC formation. Ultimately, this process led to diminished IgG1 antibody production and amelioration of autoimmune arthritis in mice.
Conclusion:
DNA hypermethylation plays a leading role in the pathogenesis of autoimmune arthritis and its targeted inhibition has therapeutic potential in arthritis management.
Insights
DNA demethylation using 5'-azacytidine (5'-azaC) ameliorated autoimmune arthritis in mice. This epigenetic therapy suppressed Aicda gene expression, reducing antibody production and inflammation.
Area of Science:
- Immunology
- Epigenetics
- Rheumatology
Background:
- Rheumatoid arthritis (RA) is linked to DNA hypermethylation, but therapeutic strategies targeting this are unexplored.
- DNA methyltransferase inhibitors, like 5 acydine (5 ac), offer potential for autoimmune arthritis treatment.
Purpose of the Study:
- To evaluate the therapeutic efficacy of 5 ac in a mouse model of autoimmune arthritis.
- To elucidate the cellular and gene regulatory mechanisms underlying 5 ac's effects.
Main Methods:
- Genome-wide DNA methylation profiling in arthritic B cells.
- Treatment of proteoglycan-induced arthritis (PGIA) mice with 5 ac.
- Assessment of antibody levels, class-switch recombination (CSR), Aicda gene expression, germinal center (GC) formation, and B cell subpopulations.
Main Results:
- 5 ac treatment ameliorated autoimmune arthritis in mice.
- Demethylation of the Ahr gene by 5 ac suppressed Aicda expression, reduced CSR, and impaired GC formation.
- This led to decreased IgG1 antibody production and reduced disease severity.
Conclusions:
- DNA hypermethylation is a key driver in autoimmune arthritis pathogenesis.
- Targeted inhibition of DNA methylation, using agents like 5 ac, demonstrates therapeutic potential for arthritis management.