title: Azacytidine Treatment Inhibits the Progression of Herpes Stromal Keratitis by Enhancing Regulatory T Cell Function.
abstract: Ocular infection with herpes simplex virus 1 (HSV-1) sets off an inflammatory reaction in the cornea which leads to both virus clearance and chronic lesions that are orchestrated by CD4 T cells. Approaches that enhance the function of regulatory T cells (Treg) and dampen effector T cells can be effective to limit stromal keratitis (SK) lesion severity. In this report, we explore the novel approach of inhibiting DNA methyltransferase activity using 5-azacytidine (Aza; a cytosine analog) to limit HSV-1-induced ocular lesions. We show that therapy begun after infection when virus was no longer actively replicating resulted in a pronounced reduction in lesion severity, with markedly diminished numbers of T cells and nonlymphoid inflammatory cells, along with reduced cytokine mediators. The remaining inflammatory reactions had a change in the ratio of CD4 Foxp3+Treg to effector Th1 CD4 T cells in ocular lesions and lymphoid tissues, with Treg becoming predominant over the effectors. In addition, compared to those from control mice, Treg from Aza-treated mice showed more suppressor activityin vitroand expressed higher levels of activation molecules. Additionally, cells inducedin vitroin the presence of Aza showed epigenetic differences in the Treg-specific demethylated region (TSDR) of Foxp3 and were more stable when exposed to inflammatory cytokines. Our results show that therapy with Aza is an effective means of controlling a virus-induced inflammatory reaction and may act mainly by the effects on Treg.IMPORTANCEHSV-1 infection has been shown to initiate an inflammatory reaction in the cornea that leads to tissue damage and loss of vision. The inflammatory reaction is orchestrated by gamma interferon (IFN-γ)-secreting Th1 cells, and regulatory T cells play a protective role. Hence, novel therapeutics that can rebalance the ratio of regulatory T cells to effectors are a relevant issue. This study opens up a new avenue in treating HSV-induced SK lesions by increasing the stability and function of regulatory T cells using the DNA methyltransferase inhibitor 5-azacytidine (Aza). Aza increased the function of regulatory T cells, leading to enhanced suppressive activity and diminished lesions. Hence, therapy with Aza, which acts mainly by its effects on Treg, can be an effective means to control virus-induced inflammatory lesions.
authors.affiliation: Department of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Siva Karthik
authors.initials: SK
authors.lastname: Varanasi
authors.affiliation: Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Pradeep B J
authors.initials: PBJ
authors.lastname: Reddy
authors.affiliation: Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Siddheshvar
authors.initials: S
authors.lastname: Bhela
authors.affiliation: Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Ujjaldeep
authors.initials: U
authors.lastname: Jaggi
authors.affiliation: Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Gimenez
authors.affiliation: Department of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee, USA btr@utk.edu.|Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Barry T
authors.initials: BT
authors.lastname: Rouse
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001374:Azacitidine / Q000494:pharmacology* / Q000627:therapeutic use; D002454:Cell Differentiation; D002478:Cells, Cultured; D018925:Chemokines / Q000096:biosynthesis; D004353:Drug Evaluation, Preclinical; D007111:Immunity, Cellular / Q000187:drug effects; D007155:Immunologic Factors / Q000494:pharmacology / Q000627:therapeutic use; D016849:Keratitis, Herpetic / Q000188:drug therapy* / Q000276:immunology / Q000821:virology; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology*
chemical_list: D000893:Anti-Inflammatory Agents; D018925:Chemokines; D007155:Immunologic Factors; D001374:Azacitidine
keywords: CD4 T cells; DNA methylation; TH1; herpes simplex virus; herpes stromal keratitis; immunopathology; inflammation; regulatory T cells