Selective ERK activation differentiates mouse and human tolerogenic dendritic cells, expands antigen-specific regulatory T cells, and suppresses experimental inflammatory arthritis.
OBJECTIVE
Most therapeutic treatments for autoimmune arthritis rely on immunosuppressive drugs, which have side effects. Although a previous study by our group showed that specific ERK activation suppressed immune responses, its application in a therapeutic setting has never been tested. The aim of the present study was to define the ERK-dependent immunosuppressive mechanisms and to apply selective ERK activation for the treatment of experimental inflammatory arthritis.


METHODS
A constitutively active ERK activator was coexpressed with a model antigen using lentivectors. Immunosuppressive mechanisms were characterized at the level of dendritic cell (DC) function, differentiation of antigen-specific Treg cells, and inhibition of inflammatory T cells. Administration of the ERK activator with antigen as a strategy to suppress inflammatory arthritis was tested in an experimental mouse model.


RESULTS
Selective ERK activation induced mouse and human DCs to secrete bioactive transforming growth factor β, a process required for suppression of T cell responses and differentiation of antigen-specific Treg cells. Treg cells strongly proliferated after antigen reencounter in inflammatory conditions, and these cells exhibited antigen-dependent suppressive activities. Inflammatory arthritis was effectively inhibited through antigen-specific mechanisms. Importantly, this strategy did not rely on identification of the initiating arthritogenic antigen. Equivalent mechanisms were demonstrated in human monocyte-derived DCs, setting the scene for a possible rapid translation of this approach to patients with rheumatoid arthritis.


CONCLUSIONS
This strategy of selective ERK activation resulted in an effective therapeutic protocol, with substantial advantages over DC or T cell vaccination.
Arce
Frederick
F
University College London, London, UK.
Breckpot
Karine
K
Stephenson
Holly
H
Karwacz
Katarzyna
K
Ehrenstein
Michael R
MR
Collins
Mary
M
Escors
David
D
D000704:Analysis of Variance; D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000378:metabolism*; D002070:Butadienes / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects / Q000276:immunology; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D051379:Mice; D009570:Nitriles / Q000494:pharmacology; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*
D002070:Butadienes; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009570:Nitriles; C113580:U 0126; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one