KN-93, an inhibitor of calcium/calmodulin-dependent protein kinase IV, promotes generation and function of Foxp3⁺ regulatory T cells in MRL/lpr mice.
OBJECTIVE
Foxp3(+) regulatory T cells (Treg) are pivotal for the maintenance of peripheral tolerance and prevent development of autoimmune diseases. We have reported that calcium/calmodulin-dependent protein kinase IV (CaMK4) deficient MRL/lpr mice display less disease activity by promoting IL-2 production and increasing the activity of Treg cells. To further define the mechanism of CaMK4 on Treg cells in systemic lupus erythematosus (SLE), we used the Foxp3-GFP reporter mice and treated them with KN-93, an inhibitor of CaMK4.


METHODS
We generated MRL/lpr Foxp3-GFP mice to record Treg cells; stimulated naïve CD4(+) T cells from MRL/lpr Foxp3-GFP mice under Treg polarizing conditions in the absence or presence of KN-93; evaluated the number of GFP positive cells in lymphoid organs and examined skin and kidney pathology at 16 weeks of age. We also examined the infiltration of cells and recruitment of Treg cells in the kidney.


RESULTS
We show that culture of MRL/lpr Foxp3-GFP T cells in the presence of KN-93 promotes Treg differentiation in a dose-dependent manner. Treatment of MRL/lpr Foxp3-GFP mice with KN-93 results in a significant induction of Treg cells in the spleen, peripheral lymph nodes and peripheral blood and this is accompanied by decreased skin and kidney damage. Notably, KN-93 clearly diminishes the accumulation of inflammatory cells along with reciprocally increased Treg cells in target organ.


CONCLUSIONS
Our results indicate that KN-93 treatment enhances the generation of Treg cells in vitro and in vivo highlighting its potential therapeutic use for the treatment of human autoimmune diseases.
Division of Rheumatology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School , Boston, MA , USA.
Tomohiro
T
Koga
Masayuki
M
Mizui
Nobuya
N
Yoshida
Kotaro
K
Otomo
Linda A
LA
Lieberman
José C
JC
Crispín
George C
GC
Tsokos
D000818:Animals; D001596:Benzylamines / Q000494:pharmacology*; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4 / Q000037:antagonists & inhibitors* / Q000276:immunology; D002452:Cell Count; D051858:Forkhead Transcription Factors; D007376:Interleukin-2; D008180:Lupus Erythematosus, Systemic / Q000201:enzymology / Q000276:immunology; D019463:Mice, Inbred MRL lpr; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D020127:Recovery of Function / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology*; D050378:T-Lymphocytes, Regulatory / Q000201:enzymology / Q000276:immunology*; D000096926:Benzenesulfonamides
D001596:Benzylamines; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D051858:Forkhead Transcription Factors; D007376:Interleukin-2; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; C498833:Foxp3 protein, mouse; C072105:KN 93; D000096926:Benzenesulfonamides; C517685:Camk4 protein, mouse
Calcium/calmodulin-dependent protein kinase IV; KN-93; organ damage; regulatory T cells; systemic lupus erythematosus