Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2024

Targeting mucosal gastrointestinal biofilms with antimicrobial peptides (#59)

Michael Michael 1 , Mark Blaskovich 1 , Markus Muttenthaler 1 2
  1. Centre for chemistry and drug discovery, Institute for Molecular Bioscience, St Lucia, QLD, Australia
  2. Faculty of Chemistry, University of Vienna, Vienna, Austria

Introduction

Gastrointestinal (GI) disorders, such as inflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS) affect ~6.8 million and ~780 million individuals globally, respectively.1–5 Mucosal-associated biofilms are highly prevalent in the GI tracts of those patients.6 Preliminary clinical work in removing these biofilms with endoscopic flushing reduces functional GI symptoms. Currently, no pharmaceutical interventions exist targeting such GI biofilms. Hence, an unmet need exists to develop oral therapeutics to target biofilms associated with gut disorders. We propose exploring antimicrobial peptides (AMPs) for oral therapeutics. AMPs, effective against bacteria, can potentially disrupt biofilms associated with GI diseases.7

Methods

We screened AMP candidates synthesised via solid-phase peptide synthesis against 2 biofilm-positive patient isolates of Streptococcus parasanguinis 102-K3/3 and Escherichia coli 104-K1 and 2 literature-control strains of Staphylococcus aureus ATCC29213 and Pseudomonas aeruginosa ATCC27853, determining a minimum inhibitory concentration (MIC), and assessed antibiofilm properties using crystal violet staining and the MBEC Assay Kit, with ongoing efforts conducting structure-activity relationship studies, and enhancing peptides gut stability for oral administration.

Results

We synthesised, purified, and screened 31 AMPs from organisms (amphibians, marsupials, and insects), confirming that 24 peptides have antimicrobial activity at 50 µM or lower. Peptide MMM02 from marsupials has the lowest MIC value of 0.8 µM for P. aeruginosa ATCC27853 and 1.6 µM for E. coli 104-K1, while MMM25 has the lowest MIC of 0.4 µM for S. aureus ATCC29213. Furthermore, MMM02 effectively eradicated biofilms of Gram-negative bacteria, while MMM06 eliminated biofilms of Gram-positive bacteria at 50 µM.

Conclusion

In summary, our research highlights the potential of AMPs as lead candidates for oral therapeutics that target gastrointestinal biofilms, addressing the urgent need for novel interventions in treating biofilm-positive patients with GI diseases, including those with IBD and IBS.

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