Are changes in plasma antimicrobial activity in response to stressors mediated via the complement system in toads?

• Grant number: 22/02159-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2022
• End date: December 31, 2022
• Field of knowledge: Biological Sciences - Physiology - Compared Physiology
• Principal Investigator: Fernando Ribeiro Gomes
• Grantee: Stefany Antunes de Oliveira Rosa
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The immune system of amphibians is very similar to that of mammals and other vertebrates, presenting surveillance functions and elimination of possible pathogens, besides being modulated in response to stressors. Despite a growing knowledge about immunomodulation associated with stress response in amphibians, the mechanisms associated with specific components of the immune system modulated by stressors are not known, especially regarding the complement system, which is an effector mechanism composed of a set of proteins present in the plasma. When activated, the complement system can promote the lysis of bacteria directly or indirectly. The present study aims to determine whether changes in the antimicrobial capacity of anuran plasma as a result of the acute stress response are mediated by the complement system in toads (Rhinella diptycha). Additionally, we intend to determine whether the observed changes are related to plasma glucocorticoid levels. To do this, we will subject adult toads to the stress of containment and immunological challenge, and evaluate the antimicrobial capacity of plasma against an in vitro pathogen (Aeromonas hydrophila). Our predictions are that the two stimuli promote changes in the antimicrobial capacity of plasma and that these changes are, at least in part, mediated via the complement system. To determine the relative importance of the complement system on the antimicrobial capacity of plasma, we will inactivate different components of the complement system by protease, heat, and tetraacetic ethylenediamine acid and compare the antimicrobial capacity of plasma against A. hydrophilicity intact and treated plasma.(AU)