Adenosine deaminase regulates Treg expression in autologous T cell‐dendritic cell cocultures from patients infected with HIV‐1. Issue 2 (26th August 2015) - Naval‐Macabuhay, Isaac
Abstract : Counteracting immunosuppression due to HIV‐1 by ADA‐mediated increase of effector responses in autologous T cells, co‐cultured with HIV‐1‐presenting cells. Abstract : Regulatory T cells have an important role in immune suppression during HIV‐1 infection. As regulatory T cells produce the immunomodulatory molecule adenosine, our aim here was to assess the potential of adenosine removal to revert the suppression of anti‐HIV responses exerted by regulatory T cells. The experimental setup consisted of ex vivo cocultures of T and dendritic cells, to which adenosine deaminase, an enzyme that hydrolyzes adenosine, was added. In cells from healthy individuals, adenosine hydrolysis decreased CD4 + CD25 hi regulatory T cells. Addition of 5′‐ N ‐ethylcarboxamidoadenosine, an adenosine receptor agonist, significantly decreased CD4 + CD25 lo cells, confirming a modulatory role of adenosine acting via adenosine receptors. In autologous cocultures of T cells with HIV‐1‐pulsed dendritic cells, addition of adenosine deaminase led to a significant decrease of HIV‐1‐induced CD4 + CD25 hi forkhead box p3 + cells and to a significant enhancement of the HIV‐1‐specific CD4 + responder T cells. An increase in the effector response was confirmed by the enhanced production of CD4 + and CD8 + CD25 − CD45RO + memory cell generation and secretion of Th1 cytokines, including IFN‐γ and IL‐15 and chemokines MIP‐1α/CCL3, MIP‐1β/CCL4, and RANTES/CCL5. These ex vivo results show, in a physiologically relevant model, that adenosine deaminase is able to enhance HIV‐1 effector responses markedly. The possibility to revert regulatory T cell‐mediated inhibition of immune responses by use of adenosine deaminase, an enzyme that hydrolyzes adenosine, merits attention for restoring T lymphocyte function in HIV‐1 infection.