Peptidylarginine Deiminase inhibition abolishes the production of large extracellular vesicles from Giardia intestinalis , affecting host-pathogen interactions by hindering adhesion to host cells

Abstract Giardia intestinalis is an anaerobic protozoan that is an important etiologic agent of inflammation-driven diarrhea worldwide. Although self-limiting, a deep understanding of the factors involved in the pathogenicity that produces the disruption of the intestinal barrier remains unknown. There is evidence that under diverse conditions, the parasite is capable of shedding extracellular vesicles (EVs) which could modulate the physiopathology of giardiasis. Here we describe new insights of G. intestinalis EV production, revealing its capacity to shed two different enriched EV populations (large and small extracellular vesicles) and identified a relevant adhesion function associated only with the larger population. Our work also aimed at assessing the influences of two recently identified inhibitors of EV release in mammalian cells, namely peptidylarginine deiminase (PAD) inhibitor and cannabidiol (CBD), on EV release from Giardia and their putative effects on host-pathogen interactions. PAD-inhibitor Cl-amidine and CBD were both able to effectively reduce EV shedding, the PAD-inhibitor specifically affecting the release of large extracellular vesicles and interfering with in vitro host-pathogen interactions. The strong efficacy of the PAD-inhibitor on Giardia EV release indicates a phylogenetically conserved pathway of PAD-mediated EV release, most likely affecting the Giardia arginine deiminase (GiADI) homolog of mammalian PADs. While there is still much to learn about G. intestinalis interaction with its host, our results suggest that large and small EVs may be differently involved in protozoa communication, and that EV-inhibitor treatment may be a novel strategy for recurrent giardiasis treatment.