We tested lapaquistat on a mouse model of Cryptosporidium infection and discovered that it did a pretty good job at restricting overall parasite burdens, and reducing numbers of visible parasites in the ileum.

16/

We made transgenic parasites to test how important those remaining glutathione-recycling genes were. We can induce loss of glutathione reductase by adding rapamycin to induce DNA excision. Parasites with induced loss of this gene did not survive in mice, showing glutathione recycling is essential.

Glutathione is one of life's ways of dealing with oxidative damage, it's a crucial metabolite across all kingdoms of life. But of course, Crypto being crypto, has lost the genes to make its own glutathione, unlike other apicomplexan parasites and most eukaryotes. But it can still use and recycle it.

We found that accumulated squalene can act as an anti-oxidant in epithelial cells. Our KO cell line that accumulates squalene had lower levels of reactive oxygen species (ROS) compared to parental controls. Plus, adding a common anti-oxidant like N-Ac boosts parasites to similar levels.

We reproduced this phenotype using chemical inhibitors of either gene (growth is either floored or enhanced) or by creating a KO cell line that accumulates squalene in host cells. This was especially true for development of parasite sexual stages which seem to teeter on the metabolite squalene.

9/

Amazingly, knocking out two consecutive genes in the human cholesterol synthesis pathway either inhibited or promoted parasite growth! This seemed to hinge on an accumulation of the intermediary metabolite squalene that is sandwiched in between these two genes.

8/

Have you ever wondered how knocking out every single gene in the human genome, one by one, might affect your intracellular pathogen of interest? We did, & boy was it a wild ride! Happy to share our preprint discovering the essential host genome for Cryptosporidium -

www.biorxiv.org/content/10.1...

Indole-3-carbinol (I3C) is a phytochemical enriched in Brassica veggies. It activates AHR. Supplementing mouse diets with I3C augments their IEL population. So we fed mice I3C and challenged them with Cryptosporidium. They were protected! I went straight home and ate some kale

Amazingly, transferring IELs to immunodeficient mice was enough to rescue them from infection-related morbidity and they had much lower parasite burdens. Go go barrier cytotoxic activity!

But what about the indoles? Here's where we got really excited -

We then narrowed this down to CD8+ intraepithelial lymphocytes (IELs). These cells highly express AHR, depend on the presence of AHR ligands, and proliferate in response to Crypto infections.

We decided to dig deeper. If AHR (& its activating ligands) can protect against Crypto, how? Using a series of transgenic mouse models, we found that AHR expression - particularly in immune cells - was important to curb Crypto infections.