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Carnosine as a protective agent in cardiac muscle tissue: advances towards its therapeutic use

Abstract

Carnosine is an intracellular dipeptide endogenously synthesised in excitable tissues, especially in striated muscles. Carnosine can be obtained from diet via meat ingestion, although it displays very poor bioavailability due to the presence of carnosinases in the gastrointestinal tract and in the blood. Carnosine has several properties that confer therapeutic and ergogenic potential, among which we highlight pH regulation, antioxidant properties, protection against protein glycation and carbonylation, and detoxification of aldehydes produced during lipid peroxidation. Our group has developed a novel knockout rat strain where the CARNS1 gene ablated, resulting in the animals being completely devoid of carnosine. This model allows for the study of the physiological functions of carnosine, and it has revealed an important role in the modulation of cardiac function via Ca2+ dynamics. In this project we will explore the protective effects of carnosine on the cardiac tissue under condition of physiological challenge and exacerbated stress, using doxorubicin as the cardiotoxicity inductor. This will be tested via manipulating intracellular carnosine content through the formation of 4 distinct groups: no carnosine (CARNS1-/- rats), normal carnosine (wild-type CARNS1+/+ rats), increased carnosine (CARNS1+/+ rats supplemented with beta-alanine), and controls. Animals from the beta-alanine group (which knowingly increases carnosine content) will receive beta-alanine in their drinking water (1,8%) from their 30th day of life for a total of 16 weeks. After 10 weeks of supplementation, they will then receive doxorubicin treatment (except for the control group) for another 6 weeks. The animals will be assessed for the following variables: in-vivo cardiac function (echocardiography); contractile function of isolated cardiomyocytes; Ca2+ transients in cardiomyocytes; mitochondrial respiration in extracts of the left ventricle; plasma markers of cardiac damage (CK-MB and troponin-I) and inflammation (IL-1¿, IL-6, e TNF-¿); morphology of the cardiac tissue assessed via light and electron transmission microscopy; markers of oxidative stress in the cardiac tissue (protein carbonyls, GSH:GSSG; 8-isoprostane, myeloperoxidase, DNA damage, and markers of ferroptosis: total cell iron and the expression of PTGS2 and CHAC1 genes); expression of proteins from Nrf2 pathway in the cardiac tissue (Nrf2, Keap1, AMPK e Nf-Kb); protein expression of pro-inflammatory cytokines in the cardiac tissue (IL-1, IL-6 e TNF-¿). Additionally, a second study will be conducted to develop and validate a process to nanoencapsulate carnosine using pectin, in an attempt to improve the pharmacokinetic properties and bioavailability of carnosine in the blood. This can likely increase its potential therapeutic use as a systemic protecting agent. The nanoparticles will be developed with auto molecular organisation to form stable nanostructures. Physiochemical characterisation as well as stability and homogeneity of the nanostructures will consider the average size (in nm), size distribuition (in PDI - polidispersivity index), and zeta potential (in mV) using the dynamic light dispersion technique. We will also analyse the morphology of the nanostructures with scanning electron microscopy. Following the development of the nanostructures, they will be tested for the ability to be digested and absorbed using an in-vitro simulated digestion/absorption system (Infogest 2.0). The resistance of the nanostructures against the action of carnosinases will be determined in a carnosine hydrolysis assay in human serum comparing carnosine vs. nanoencapsulated carnosine. (AU)

Articles published in Agência FAPESP Newsletter about the research grant:
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VEICULO: TITULO (DATA)