Methylglyoxal - advanced glycation end products (AGEs) - receptor for AGEs (AGEr) axis: A potential therapeutical target for prevention and treatment of bladder dysfunction associated with obesity and diabetes

• Grant number: 24/10306-4
• Support Opportunities: Regular Research Grants
• Start date: April 01, 2025
• End date: March 31, 2028
• Field of knowledge: Biological Sciences - Pharmacology - Autonomic Pharmacology
• Principal Investigator: Edson Antunes
• Grantee: Edson Antunes
• Host Institution: Faculdade de Ciências Médicas (FCM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated scholarship(s): 25/10412-1 - Study of diabetic bladder dysfunction in leptin-deficient mice (ob/ob): impact of chronic methylglyoxal administration, BP.MS

Abstract

Overview: Diabetes mellitus promotes an array of complications in the body, including micturition (voiding) dysfunction that is referred to as diabetic bladder dysfunction (DBD) or diabetic cystopathy. Voiding dysfunction comprises clinical manifestations which may progress from detrusor smooth muscle overactivity to underactive (hypoactive). During hyperglycemic states there is a marked elevation in the levels of ¿-dicarbonyl compounds, including methylglyoxal (MGO), leading to the formation of advanced glycation end products (AGEs), such as methylglyoxal-hydroimidazolone (MG-H1), amongst others. Glyoxalases (GLO) enzymes, consisting of GLO1 and GLO2, regulate the excess of AGEs in the body by promoting the MGO degradation into lactate. AGEs interact with its cell surface receptor (here termed AGEr or RAGE), elevating the levels of reactive-oxygen species (ROS). The glycation by MGO of extracellular matrix protein such as collagen may be implicated in DBD physiopathology. Research basis, objectives, and main questions to be answered: Prolonged administration of MGO to normoglycemic mice changes the voiding pattern in favor to increases of capacity and residual volume and causes in vitro detrusor overactivity, which are accompanied by increased ROS generation and collagen deposition in bladder tissues. The genetically obese and diabetic ob/ob mice also exhibit high MGO levels, accompanied by elevated levels of total AGEs, MG-H1, AGEr and collagen in the bladder tissues. The ob/ob mice manifest voiding alterations such as increased total void volume and volume per void, and in vitro detrusor overactivity. However, the literature on the role of the MGO-AGEs-AGEr axis in micturition disorders linked to diabetes/obesity remains scarce, being basically restricted to the works of our research group. In this project we aim to answer if DBD reflects endogenous MGO accumulation and AGEs formation, resulting in persistent AGEr activation and ROS generation in bladder tissues, which may be related or not to MGO detoxification by GLO enzymes. We divided the proposal into two subprojects, namely: Subproject #1: In animal models of type 2 (ob/ob and db/db), type 1 DM (NOD; non-obese diabetic mice), we aim to answer whether bladder dysfunction is due to endogenous accumulation of MGO and the formation of AGEs, resulting in persistent activation of RAGE and formation of ROS in the bladder, which may or may not be associated with changes in the detoxification system of MGO. Subproject #2: we aim to evaluate whether in vitro incubation with MGO in isolated bladders of normoglycemic (control) and hyperglycemic (ob/ob, db/db, and NOD) animals mimics the changes in detrusor contractility observed in vivo; and whether such changes are due to the activation of the AGEs-AGEr-ROS axis in the bladder wall, which may or may not be associated with defects in the activity/expression of glyoxalase. In human bladder samples obtained from either deceased donors or from patients undergoing bladder enlargement surgery, we will test the effects of MGO in vitro upon the detrusor contractility, and if the responses mimic those of mice we will evaluate the markers for the MGO-AGEs-RAGE axis and glyoxalases. Methods: We will perform techniques for in vivo evaluation of micturition behavior (filter paper technique in awake animals) and cystometric (in anesthetized animals), as well as bladder contractility in vitro, which will be accompanied by quantification of biochemical and molecular markers of the MGO-AGEs-RAGE axis in the bladder. The selective inhibition/antagonism of the MGO-AGEs-RAGE-ROS axis will also be employed through the use of RAP (AGEr antagonist peptide), azeliragon (orally bioavailable AGEr inhibitor), FPS-ZM1 (AGEr inhibitor), alagebrium (AGE "breaker"), GSK2795039 (NOX2 inhibitor), GKT137831 (NOX1/4 inhibitor), GLX351322 (NOX4 inhibitor), and HY-146656 (GLO1 inhibitor). Why is our group suitable to answer these questions? In recent years, we have (AU)