Análise da virulência de biofilmes de Candida albicans desenvolvidos sob diferentes condições

Author(s)

Yuri Wanderley Cavalcanti

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2015-06-02

Examining board members

Wander José da Silva; Raphael Freitas de Souza; William Custodio; Cinthia Pereira Machado Tabchoury; Valentim Adelino Ricardo Barão

• Advisor: Wander José da Silva; Altair Antoninha Del Bel Cury

Abstract

Candida infections have high prevalence; therefore, better understanding of the development mechanisms of biofilms is required for the reduction of virulence and for more appropriated clinical management. The aim of this study was to analyse the virulence of Candida albicans biofilms developed under different conditions. The role of biomaterial surfaces, salivary pellicle, and stage of biofilm development has been reported in Chapter 1. The influence of the presence of other microorganisms in virulence of C. albicans and on the interaction with the epithelium was evaluated in Chapter 2. The role of the atmosphere and of the biofilm¿s bacterial population was investigated in Chapter 3. In Chapter 1, C. albicans biofilms were developed on acrylic resin and titanium discs coated with saliva pellicle, or saliva with blood plasma pellicle. The materials¿ surfaces were analysed with regards to surface roughness and surface free energy (SFE). We evaluated the number of viable organisms, the DNA concentration, the metabolic activity, the expression of virulence factors and the architecture of the biofilms. There were no differences in the surface roughness of materials. The pellicles eliminated the differences between SFE of materials. Higher SFE was observed for discs coated with pellicles of saliva with plasma. The number of viable organisms, the DNA concentration and the metabolic activity increased throughout the biofilm maturation. Higher metabolic activity, increased expression of ALS1, ALS3 and HWP1, and more hyphae were observed in biofilms grown in the presence of saliva with plasma pellicle. There were no differences between the materials. In conclusion, the presence of saliva with plasma pellicle increases the C. albicans virulence. In chapter 2, mature biofilms (72 h) of C. albicans, or C. albicans with bacteria, were developed on the surface of acrylic resin discs. These biofilms were then analysed or used to infect a reconstituted human oral epithelium model (RHOE). Biofilms were evaluated according to the number of hyphae and the expression of virulence factors. The epithelial response was evaluated by the expression of IL-18 and Dectin1, by the activity of lactate dehydrogenase enzyme (LDH), and with regards the epithelial invasion. Increased number of hyphae and increased expression of HWP1, SAP4 and SAP6 were observed in multi-species biofilms developed on acrylic. Multi-species biofilms that have infected RHOE also had a greater number of hyphae and increased expression of ALS3, EPA1, SAP6 and HWP1. Consequently, these epithelia showed greater tissue invasion, higher LDH activity and higher IL-18 expression. We concluded, therefore, that the presence of bacteria promotes the virulence and pathogenicity of C. albicans. In Chapter 3, biofilms of C. albicans and C. albicans with streptococci were developed on titanium, aerobically and anaerobically. C. albicans biofilms (mixed or not-mixed with streptococci) were also grown in the presence Porphyromonas gingivalis, anaerobically. Biofilms were evaluated according to the formation of hyphae and expression of virulence factors. Anaerobic conditions and co-cultivation of streptococci produced higher number of hyphae and increased expression of virulence factors. Although P. gingivalis has inhibited the virulence of C. albicans, this effect was reversed in the presence of streptococci. We concluded that the anaerobic atmosphere and the presence of streptococci stimulate the C. albicans virulence (AU)

• FAPESP's process: 12/07436-6 - Analysis of the virulence of Candida albicans biofilms developed under different conditions
• Grantee: Yuri Wanderley Cavalcanti
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)