Correlation Between ROS Production and InsP3 Released by Granulocytes from Type 1 Diabetic Patients in a cAMP-Dependent Manner

Miriam      Martins Chaves; Daniela      Caldeira Costa; Denniece Adriana      da Costa Souza; Francisco das      Chagas Lima e Silva; Jose Augusto      Nogueira Machado

Abstract

Background: Diabetes is associated with a pro-inflammatory status characterized by an increased production of inflammatory molecules. Reactive Oxygen Species (ROS) and cAMP elevating agents represent two molecular systems, normally generated during inflammation. These molecules could be responsible for the alteration of signaling pathways. In the present paper we have studied the correlation between ROS generation and inositolpolyphosphates (InsP1, InsP2 InsP3 and InsP4) released by granulocytes from Type 1 diabetic patients (DM1) in the presence or in the absence of cyclic AMP-elevating agents. Methods: The effect of cAMP on ROS production was quantified in a chemoluminescence assay luminol-dependent (RLU/min). InsP1, InsP2 InsP3 and InsP4 were quantified by inositol-H3 in a Beta-counter and the results were expressed as count per minute (CPM). Results: The elevation of intracellular level of cAMP inhibited both InsP3 and ROS production in granulocytes from healthy subjects and activated in the cells from Type 1 diabetic patients. InsP1, InsP2 and InsP4 did not show significant alteration in both studied cells. There was a significant correlation between InsP3 and ROS in the presence of elevated content of cAMP. This correlation was observed in a 15 minutes reaction for healthy subjects and in 120 minutes for DM1. Conclusions: The importance of both InsP3 release and ROS production in an inflammatory process and tissue pathophysiology in Type 1 diabetic patients is still under debate because hyperglycemia accelerates generation of oxidative stress and may play an important role in the development of complications in diabetes. Thus, our results demonstrated alteration in metabolic response in granulocytes from Type 1 diabetic patients and it may be important for the development of therapeutic processes and drugs that interfere with signaling of ROS generation and may contribute to the improvement of the severe complications of diabetes.

Keywords: Type 1 diabetes, neutrophil, InsP3, ROS

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