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Authors
Advisor(s)
Abstract(s)
A resistência antimicrobiana de agentes patogénicos como o Staphylococcus aureus resistente à meticilina (MRSA) é uma enorme preocupação de saúde pública a nível mundial. Atualmente, várias abordagens de combate a estes microrganismos estão a ser desenvolvidas, incluindo a utilização de compostos com potencial terapêutico como as catequinas do chá verde. A epigalocatequina-3-galato (EGCG) é a catequina do chá com maior relevância clínica, apresentando um forte poder anti-inflamatório, antioxidante, anticancerígeno, antimicrobiano e demonstrando sinergismo com diversos antibióticos. A exposição a EGCG afeta a transcrição de vários genes em S. aureus, incluindo genes relacionados com fatores de virulência, como hlgA, hlgB que codificam subunidades hemolisantes gama A e B, respetivamente e hly, que codifica um precursor de alfa-hemolisina. O objetivo deste estudo foi avaliar os efeitos da exposição ao EGCG nos padrões de transcrição de hlgA, hlgB e hly em estirpes de S. aureus com fenótipos de resistência divergentes. Foram utilizadas estirpes com diferentes origens, perfis de resistência, e sinergismo da EGCG com vários antibióticos. Os níveis transcricionais dos genes selecionados foram determinados por extração do RNA, conversão em cDNA e quantificação por qRT-PCR utilizando primers específicos, seguidas de tratamento estatístico. A análise de resultados demonstra que fenótipos de resistência divergentes estão associados a expressões transcricionais diferentes: mais elevadas nas estirpes nosocomiais que comensais, e mais reduzidos após exposição. Também se observou que hly teve maior expressão transcricional pré-exposição. Os dados analisados sugerem uma correlação entre a modulação epigenética e a expressão de fatores de virulência. Este estudo permite assim acumular evidências que sugerem que o EGCG pode ser uma nova opção terapêutica no combate à resistência a antibióticos.
ABSTRACT - Antimicrobial resistance of pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) is a major public health concern worldwide. Currently, several approaches are being developed to fight against these microorganisms, including the use of compounds with therapeutic potential such as green tea catechins. Epigallocatechin-3 gallate (EGCG) is the most abundant catechin in tea and the most medically relevant, with anti-inflammatory, antioxidant, and anti-carcinogenic properties, high antimicrobial potential, and reported synergism with several antibiotics. It has been shown that EGCG exposure alters the transcription of numerous genes in S. aureus, including genes implicated in toxins, such as hlgA, hlgB which encode the gamma haemolysing subunits A and B, respectively, and hly, which encodes for an alpha-hemolysin-precursor. In this study, we aimed to assess the effects of EGCG exposure in the transcriptional patterns of hlgA, hlgB, and hly in S. aureus strains with divergent resistance phenotypes. Transcriptional levels of selected genes were determined, by bacterial RNA extraction, conversion into cDNA, and quantification by qRT-PCR, followed by statistical treatment. Overall, our results show that divergent resistance phenotypes are associated with differential transcriptional expressions of the studied genes: upregulation in nosocomial strains, when compared to commensal ones, and downregulation after exposure to EGCG, although the patterns were different in hlgA and hlgB/hly. Also, hly had higher transcriptional expression before exposure to EGCG than the other two analyzed genes. Data suggests a correlation between epigenetic modulation and the expression of virulence factors namely hemolysins. This study increases scientific knowledge and has allowed the production of accumulating evidence to suggest that EGCG could be a novel therapeutic option in the fight against antibiotic resistance.
ABSTRACT - Antimicrobial resistance of pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) is a major public health concern worldwide. Currently, several approaches are being developed to fight against these microorganisms, including the use of compounds with therapeutic potential such as green tea catechins. Epigallocatechin-3 gallate (EGCG) is the most abundant catechin in tea and the most medically relevant, with anti-inflammatory, antioxidant, and anti-carcinogenic properties, high antimicrobial potential, and reported synergism with several antibiotics. It has been shown that EGCG exposure alters the transcription of numerous genes in S. aureus, including genes implicated in toxins, such as hlgA, hlgB which encode the gamma haemolysing subunits A and B, respectively, and hly, which encodes for an alpha-hemolysin-precursor. In this study, we aimed to assess the effects of EGCG exposure in the transcriptional patterns of hlgA, hlgB, and hly in S. aureus strains with divergent resistance phenotypes. Transcriptional levels of selected genes were determined, by bacterial RNA extraction, conversion into cDNA, and quantification by qRT-PCR, followed by statistical treatment. Overall, our results show that divergent resistance phenotypes are associated with differential transcriptional expressions of the studied genes: upregulation in nosocomial strains, when compared to commensal ones, and downregulation after exposure to EGCG, although the patterns were different in hlgA and hlgB/hly. Also, hly had higher transcriptional expression before exposure to EGCG than the other two analyzed genes. Data suggests a correlation between epigenetic modulation and the expression of virulence factors namely hemolysins. This study increases scientific knowledge and has allowed the production of accumulating evidence to suggest that EGCG could be a novel therapeutic option in the fight against antibiotic resistance.
Description
Mestrado em Tecnologias Clínico-Laboratoriais
Keywords
EGCG MRSA Antibiotic resistance Transcription modulation Hemolysins Resistência a antibióticos Modulação da transcrição Hemolisinas
Pedagogical Context
Citation
Almeida RP. Modulatory effect of epigallocatechin-3-gallate in Staphylococcus aureus toxin production genes transcription [dissertation]. Lisboa: Escola Superior de Tecnologia da Saúde de Lisboa/Instituto Politécnico de Lisboa; 2022.
Publisher
Instituto Politécnico de Lisboa, Escola Superior de Tecnologia da Saúde de Lisboa