The role of O-GlcNAc in increased release of cytokines and cardiovascular function in mice with Systemic Inflammatory Response Syndrome (SIRS)

Abstract

The O-GlcNAc process is characterized by adding a simple carbohydrate [N-acetylglucosamine (GlcNAc)] to the complex hydroxyl (O) from serine (Ser) and threonine (Thr) located in nuclear and cytoplasmic proteins. The increased O-GlcNAc reduces the release of inflammatory mediators such as interleukin-1² (IL-1²), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-±) as well as the activation of nuclear factor kappa B (NF-kB) on immune cells. In systemic inflammatory response syndrome (SIRS, Systemic Inflammatory Response Syndrome), the initial events involve the activation of inflammatory cells, increased levels of cytokines, and production of reactive oxygen species (ROS). The hypothesis for this study is that increased O-GlcNAc modification after the start of SIRS, reduces the levels of IL-1², IL-6, and TNF-±, NF-kB activation, thereby reducing cardiovascular complications and septic shock. As SIRS experimental model will use mice subjected to administration of lipopolysaccharide (LPS). The animals receive injections of glucosamine and/or enzyme inhibitor OGA - thiamet-L (which increase protein levels of O-GlcNAc modified) or vehicle for determining the effects of an acute increase of O-GlcNAc on survival/mortality in the production and release of cytokines by inflammatory and vascular cells, vascular reactivity and the blood pressure changes induced by SIRS. Vascular reactivity will be assessed in rings of the thoracic aorta and mesenteric artery, and the levels of cytokines/activation of NF-kB are determined by ELISA and western blot. Preliminary data from our laboratory demonstrated that prior administration of glucosamine (before administration of LPS) attenuates the release of inflammatory mediators and cardiovascular changes observed in SIRS. In this project, we will test the effects of increased O-GlcNAc, after the installation of SIRS. This study presents scientific relevance since the O-GlcNAc is considered an additional mechanism of control of intracellular signaling and the SIRS represents an important pathology cause of death in patients hospitalized in intensive care units. Studies of the effects of changes by O-GlcNAc is essential to clarify the role of post-translational modification in pathophysiological conditions such as SIRS. (AU)