Role of the CFTR in pathogenesis of Giardia duodenalis infections

Introduction

As a widespread protozoal parasite, Giardia duodenalis is a common cause for malabsorption and diarrhea. Intestinal epithelial barrier defects are frequently observed in patients affected by the multifactorial disease giardiasis. While the exact pathomechanisms remain unknown, recent findings suggest a novel chain of events amounting in epithelial barrier breakdown, which starts with a disturbed ion homeostasis during the early infection phase. Amongst intestinal ion transporters, the anion channel CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) has been shown to be severely affected by Giardia, i.e. resulting in reduced protein expression and function.

Goals

We aim to shed light on the putative role of the CFTR channel in G. duodenalis infections by investigating its impact on pathogenesis at different infection stages.

Materials & Methods

Using CRISPR/Cas9-technology, intestinal organoids from a healthy, CFTR wildtype donor were converted into CFTR-impaired CF-mimicking mutants. For comparison of CFTR-mutant and wildtype, the respective isogenic organoids were cultured in a compartmentalized transwell system, infected with G. duodenalis and the host response was analyzed at transcriptome level using single-cell RNA-sequencing (scRNAseq).

Results

scRNAseq experiments confirm a robust transcriptional downregulation of the CFTR ion transporter upon infection. Transcriptomic changes in intestinal organoids hint towards a severely altered host lipid metabolism and mitochondrial dysfunction in the late infection stage, which is significantly more pronounced in CFTR-impaired organoids.

Summary

Due to the significant downregulation of the CFTR ion channel during G. duodenalis infections and its pathogenic role in a variety of different diseases, we hypothesized that CFTR non-functionality may play a greater role in giardiasis pathogenesis. Experiments using CFTR-impaired organoids indeed suggest an increased susceptibility to lipid imbalances and mitochondrial dysfunction downstream of functional CFTR impairment.