THU0057 Kn-93, an Inhibitor of Calcium/Calmodulin-Dependent Protein Kinase Iv, Promotes Generation and Function of Foxp3+ Regulatory T Cells in Mrl/Lpr Mice
Authors: T. Koga, M. Mizui, N. Yoshida, K. Otomo, L.A. Lieberman, J.C. Crispín, A. Kawakami, G.C. Tsokos
Journal: Annals of the Rheumatic Diseases (2014)

<h3>Background</h3> Autoimmune diseases such as systemic lupus erythematosus (SLE) display quantitative (1) and/or qualitative (2) deficiencies of Foxp3<sup>+</sup> regulatory T (T<sub>reg</sub>) cells and this is considered to contribute to immune dysregulation and organ damage (3). Calcium/calmodulin-dependent protein kinase IV (CaMK4) is expressed at increased levels in T cells from SLE patients (4) and lupus-prone mice (5). <h3>Objectives</h3> T<sub>reg</sub> are pivotal for the maintenance of peripheral tolerance and prevent development of autoimmune diseases. We have reported that CaMK4 deficient MRL/<i>lpr</i> mice display less disease activity by promoting IL-2 production and increasing the activity of T<sub>reg</sub> cells. To further define the mechanism of CaMK4 on T<sub>reg</sub> cells in SLE, we used the <i>Foxp3</i>-GFP reporter mice and treated them with KN-93, an inhibitor of CaMK4. <h3>Methods</h3> We generated MRL/<i>lpr Foxp3-</i>GFP mice to record T<sub>reg</sub> cells; stimulated naïve CD4<sup>+</sup> T cells from MRL/<i>lpr Foxp3-</i>GFP mice under T<sub>reg</sub> 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 week of age. We also examined the infiltration of cells and recruitment of T<sub>reg</sub> cells in the kidney. <h3>Results</h3> We show that culture of MRL/<i>lpr Foxp3-</i>GFP T cells in the presence of KN-93 promotes T<sub>reg</sub> differentiation in a dose dependent manner (Fig. F). Treatment of MRL/<i>lpr Foxp3-</i>GFP mice with KN-93 results in significant induction of T<sub>reg</sub> cells in the spleen, peripheral lymph nodes (Fig. B-E) and peripheral blood (Fig. A and B) and this is accompanied by decreased skin and kidney damage. Notably, KN-93 clearly diminishes the accumulation of inflammatory cells along with reciprocally increased T<sub>reg</sub> cells in target organ. <h3>Conclusions</h3> Our results indicate that KN-93 treatment enhances the generation of T<sub>reg</sub> cells <i>in vitro</i> and <i>in vivo</i> highlighting its potential therapeutic use for the treatment of human autoimmune diseases. <h3>References</h3> Valencia X, Yarboro C, Illei G, Lipsky PE. Deficient CD4+CD25high T regulatory cell function in patients with active systemic lupus erythematosus. J Immunol. 2007;178(4):2579-88. Yan B, Ye S, Chen G, Kuang M, Shen N, Chen S. Dysfunctional CD4+,CD25+ regulatory T cells in untreated active systemic lupus erythematosus secondary to interferon-alpha-producing antigen-presenting cells. Arthritis Rheum. 2008;58(3):801-12. Shevach EM. Mechanisms of foxp3+ T regulatory cell-mediated suppression. Immunity. 2009;30(5):636-45. Juang YT, Wang Y, Solomou EE, Li Y, Mawrin C, Tenbrock K, et al. Systemic lupus erythematosus serum IgG increases CREM binding to the IL-2 promoter and suppresses IL-2 production through CaMKIV. J Clin Invest. 2005;115(4):996-1005. Koga T, Ichinose K, Mizui M, Crispin JC, Tsokos GC. Calcium/Calmodulin-Dependent Protein Kinase IV Suppresses IL-2 Production and Regulatory T Cell Activity in Lupus. J Immunol. 2012;189(7):3490-6. <h3>Acknowledgements</h3> This work was supported by NIH grants RO1 AI R01AI085567 and AR064350. <h3>Disclosure of Interest</h3> : None declared <h3>DOI</h3> 10.1136/annrheumdis-2014-eular.2491