Regulation of A2A adenosine receptor mediated cytokine production by the inhibition of Cathepsin D

Ariaga Anderson Chukwuka; General Medicine II.
REGULATION OF A2A ADENOSINE RECEPTOR MEDIATED CYTOKINE PRODUCTION BY INHIBITION OF CATHEPSIN D

Our research group identified earlier the interaction of A2A receptor and Cathepsin D (CtsD) in mice peritoneal macrophages (IPMQs). CtsD is an aspartic protease found mainly in the lysosome. When lysosomal membranes become permeable or when lysosome trafficking occurs and they fuse with phagosomes or plasma membrane, cathepsins are released and play an important role in immune response and cell apoptosis/necrosis through cytokine regulation respectively.
Adenosine A2A is a seven trans membrane, G-protein coupled receptor that have been shown to mediate cytokine production and regulate lysosome trafficking and hence CtsD localisation in lipopolysaccharide (LPS) activated macrophages.
The aim of our experiments was to study the functional relationship between CtsD and A2A receptor mediated cytokine release in macrophages. We measured the cAMP level and the cytokine production of LPS activated macrophages in the presence or absence of aspartyl protease inhibitor, Pepstatin A by ELISA method.
In our experiments, we could successfully inhibit the aspartic protease activity in the lysate of activated mice IPMQ cells and we observed elevated level of cAMP in the presence of Pepstatin A. The cytokines production of the macrophages also changed after the Pepstatin A treatment. We detected decreased level of inflammatory TNF-α and IL-6 and increased level of anti-inflammatory IL-10 cytokines production of the activated macrophage cells.
On the basis of our results, it is shown that Pepstatin A has an effect on the A2A mediated cytokine production of LPS activated IPMQs mainly through the regulation of cAMP production. This could be an important factor in treatment of a number of inflammatory diseases such as inflammatory bowel disease (Crohn’s disease, ulcerative colitis) by suppression of inflammatory cytokine production.

Supervisor: Endre Kókai.