Binding and neutralization of C. difficile toxins A and B by purified clinoptilolite-tuff

PLoS One. 2021 May 27;16(5):e0252211. doi: 10.1371/journal.pone.0252211. eCollection 2021.

Abstract

Clostridioides difficile (C. difficile) infection is a major public health problem worldwide. The current treatment of C. difficile-associated diarrhea relies on the use of antibacterial agents. However, recurrences are frequent. The main virulence factors of C. difficile are two secreted cytotoxic proteins toxin A and toxin B. Alternative research exploring toxin binding by resins found a reduced rate of recurrence by administration of tolevamer. Hence, binding of exotoxins may be useful in preventing a relapse provided that the adsorbent is innocuous. Here, we examined the toxin binding capacity of G-PUR®, a purified version of natural clinoptilolite-tuff. Our observations showed that the purified clinoptilolite-tuff adsorbed clinically relevant amounts of C. difficile toxins A and B in vitro and neutralized their action in a Caco-2 intestinal model. This conclusion is based on four independent sets of findings: G-PUR® abrogated toxin-induced (i) RAC1 glucosylation, (ii) redistribution of occludin, (iii) rarefaction of the brush border as visualized by scanning electron microscopy and (iv) breakdown of the epithelial barrier recorded by transepithelial electrical resistance monitoring. Finally, we confirmed that the epithelial monolayer tolerated G-PUR® over a wide range of particle densities. Our findings justify the further exploration of purified clinoptilolite-tuff as a safe agent in the treatment and/or prevention of C. difficile-associated diarrhea.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism*
  • Bacterial Toxins / metabolism*
  • Caco-2 Cells
  • Clostridioides difficile / immunology*
  • Clostridium Infections / prevention & control*
  • Enterotoxins / metabolism*
  • Humans
  • Protein Binding
  • Virulence Factors / metabolism*
  • Zeolites / pharmacology*

Substances

  • Bacterial Proteins
  • Bacterial Toxins
  • Enterotoxins
  • Virulence Factors
  • tcdA protein, Clostridium difficile
  • toxB protein, Clostridium difficile
  • clinoptilolite
  • Zeolites

Grants and funding

Shahrooz Nasrollahi-Shirazi is supported by the doctorate college CCHD (Cell Communications in Health and Disease), which is jointly funded by the FWF (W1205) and the Medical University of Vienna. Glock Health, Science and Research GmbH provided support in the form of research materials and salaries for authors C.R., D.N., A.S., A.R., C.T. and S.N., but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.