RESUMO
Uropathogenic Escherichia coli (UPEC) strains cause symptomatic urinary tract infections in humans whereas commensal-like E. coli strains in the urinary bladder cause long-term asymptomatic bacteriuria (ABU). We previously reported that UPEC and ABU strains differentially regulate key DNA methylation and histone acetylation components in the surrogate insect host Galleria mellonella to epigenetically modulate innate immunity-related gene expression, which in turn controls bacterial growth. In this follow-up study, we infected G. mellonella larvae with UPEC strain CFT073 or ABU strain 83972 to identify differences in the expression of microRNAs (miRNAs), a class of non-coding RNAs that regulate gene expression at the post-transcriptional level. Our small RNA sequencing analysis showed that UPEC and ABU infections caused significant changes in the abundance of miRNAs in the larvae, and highlighted the differential expression of 147 conserved miRNAs and 95 novel miRNA candidates. We annotated the G. mellonella genome sequence to investigate the miRNA-regulated expression of genes encoding antimicrobial peptides, signaling proteins, and enzymatic regulators of DNA methylation and histone acetylation in infected larvae. Our results indicate that miRNAs play a role in the epigenetic reprograming of innate immunity in G. mellonella larvae to distinguish between pathogenic and commensal strains of E. coli.
Assuntos
Infecções por Escherichia coli/genética , Imunidade Inata/genética , MicroRNAs/genética , Escherichia coli Uropatogênica/genética , Acetilação , Animais , Metilação de DNA/genética , DNA Bacteriano/genética , DNA Bacteriano/imunologia , Modelos Animais de Doenças , Infecções por Escherichia coli/microbiologia , Expressão Gênica/genética , Genoma de Inseto/genética , Histonas/genética , Humanos , Larva/microbiologia , MicroRNAs/classificação , Anotação de Sequência Molecular , Mariposas/imunologia , Mariposas/microbiologia , Bexiga Urinária/microbiologia , Infecções Urinárias/genética , Infecções Urinárias/microbiologia , Escherichia coli Uropatogênica/patogenicidade , Virulência/genéticaRESUMO
Current antibiotics cannot eradicate uropathogenic Escherichia coli (UPEC) biofilms, leading to recurrent urinary tract infections. Here, we show that the insect antimicrobial peptide cecropin A (CecA) can destroy planktonic and sessile biofilm-forming UPEC cells, either alone or when combined with the antibiotic nalidixic acid (NAL), synergistically clearing infection in vivo without off-target cytotoxicity. The multi-target mechanism of action involves outer membrane permeabilization followed by biofilm disruption triggered by the inhibition of efflux pump activity and interactions with extracellular and intracellular nucleic acids. These diverse targets ensure that resistance to the CecA + NAL combination emerges slowly. The antimicrobial mechanisms of CecA, thus, extend beyond pore-forming activity to include an unanticipated biofilm-eradication process, offering an alternative approach to combat antibiotic-resistant UPEC infections.