atl-146e and Graft-vs-Host-Disease

Graft-versus-host disease (GVHD) remains a significant complication of allogeneic transplantation. We previously reported that the adenosine A(2A) receptor (A(2A)R) specific agonist, ATL146e, decreases the incidence and severity of GVHD in a mouse transplant model. There is increasing interest in treatments that increase CD4(+)CD25(high)Foxp3(+) regulatory T cells (Tregs) to suppress GVHD. Our current study found in vitro that A(2A)R selective agonists enhanced TGF-β-induced generation of mouse Tregs 2.3- to 3-fold. We demonstrated in vivo suppression of GVHD with specific A(2A)R agonists in two different murine GVHD transplant models associated with profound increases in both circulating and target tissue Tregs of donor origin. Three different A(2A)R agonists of differing potency, ATL146e, ATL370, and ATL1223, all significantly inhibited GVHD-associated weight loss and mortality. At the same time, Tregs shown to be of donor origin increased 5.1- to 7.4-fold in spleen, 2.7- to 4.6-fold in peripheral blood, 2.3- to 4.7-fold in colon, and 3.8- to 4.6-fold in skin. We conclude that specific activation of A(2A)R inhibits acute GVHD through an increase of donor-derived Tregs. Furthermore, the increased presence of Tregs in target tissues (colon and skin) of A(2A)R-specific agonist-treated mice is likely the mechanistic basis for the anti-inflammatory effect preventing acute GVHD.

Topics: Adenosine A2 Receptor Agonists; Animals; Cell Differentiation; Cells, Cultured; Cyclohexanecarboxylic Acids; Down-Regulation; Female; Graft vs Host Disease; Immune Tolerance; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Inbred DBA; Mice, Knockout; Purines; T-Lymphocytes, Regulatory; Transforming Growth Factor beta; Up-Regulation

GVHD is a major barrier to broader use of allogenic HSCT for nonmalignancy clinical applications such as the treatment of primary immunodeficiencies and hemoglobinopathies. We show in a murine model of C57BL/6J (H2-k(b)) --> B6D2F1/J (H2-k(b/d)) acute GVHD that when initiated 2 days before transplant, the activation of the adenosine A(2A)R with the selective agonist ATL146e inhibits the weight loss and mortality associated with disease progression. Furthermore, circulating levels of proinflammatory cytokines and chemokines, including IFN-gamma, IL-6, CCL2, KC, and G-CSF, are reduced significantly by 14-day ATL146e treatment. The up-regulation of CD25, CD69, and CD40L expression by donor CD4(+) and CD8(+) T cells is inhibited by A(2A)R activation; fewer CD3(+) T cells are found in the liver, skin, and colon of ATL146e-treated mice as compared with vehicle-treated controls; and associated tissue injury is lessened. The delayed administration of ATL146e, beginning 9 days after HSCT, reverses GVHD-associated body weight loss successfully, and improvement is sustained for the duration of treatment. We conclude that the selective activation of the A(2A)R has therapeutic potential in the prevention and treatment of acute GVHD.

Topics: Acute Disease; Adenosine A2 Receptor Agonists; Animals; Antigens, CD; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cyclohexanecarboxylic Acids; Cytokines; Disease Models, Animal; Female; Gene Expression Regulation; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Mice; Purines; Receptor, Adenosine A2A; Transplantation, Homologous