Possible evidences of ER and mitochondria participation in neutrophil HL-60 differentiated death under hyperglycemia condition

Abstract

Neutrophils are phagocytic cells that act on the first line of defense against invading microorganisms. These cells have an important role in initiating and sustaining the inflammatory process, and contribute in the regulation of immune reactions. In some pathological conditions, various functions of neutrophils are impaired, which causes a greater susceptibility of inflammation and complications in the resolution of this process. (Djaldetti et al., 2002). Diabetes mellitus is a syndrome characterized by high blood glucose (hyperglycemia) due to a dysfunction in insulin secretion and/or peripheral resistance to this hormone, causing problems in the homeostasis of the metabolism of carbohydrates, lipids and proteins (Wolff, 1993; Courten et al., 1998). In this syndrome, there are several changes in neutrophil functions, including changes in the death process, which may affect the resolution of the inflammatory condition in diabetic patients. However, how this syndrome affects the death of polymorphonuclear cells is not well understood. Recently, evidence of the endoplasmic reticulum contribution in the process of cell death was shown. This organelle may appear under stress condition due to changes in protein formation, and it is another possible site of production of ROS, besides NADPH oxidase and the mitochondria itself, and exacerbates the cascade of reactions resulting from reticulum stress. Thus, this project aims to evaluate the functions of the endoplasmic reticulum and mitochondria in HL-60 cells differentiated into neutrophils under conditions of hyperglycemia. To this end, immunofluorescence microscopy will be used to evaluate the possible reticulum stress generated by hyperglycemia, by marking the ER chaperones GRP78/Bip and Grp94; Fura-2 will be used to measure the influx/efflux and intracellular calcium dynamics of this ion; and, finally, possible disturbance in the reactive oxygen species (ROS) production by the cell, specifically by the mitochondria, will be measured by using MitoSOX and Hidroetidin. (AU)