Synthetic DEFB1-mRNA induces β-Defensin 1, reducing *Cryptosporidium parvum* infection 80% in human intestinal cells

Current treatments for cryptosporidiosis, a severe diarrheal disease caused by Cryptosporidium, are inadequate, especially for immunocompromised patients and malnourished children. The only FDA-approved drug, nitazoxanide, has limited efficacy in these vulnerable groups. Host-directed therapy (HDT), which leverages the body's own defenses, offers a promising alternative. Intestinal epithelial cells naturally produce antimicrobial peptides like β-defensins (DEFBs) to protect the mucosa. Specifically, human DEFB1 has demonstrated anti-cryptosporidial activity, making its induction a compelling therapeutic strategy.

Researchers investigated the protective effect of synthetic DEFB1-mRNA against Cryptosporidium parvum infection in human intestinal cells. HCT-8 cells were transfected with synthetic, co-transcriptionally capped DEFB1-mRNA or control mRNAs, complexed with Lipofectamine MessengerMAX. Transfection efficiency was confirmed via EGFP expression. After 24 hours, cells were challenged with excysted C. parvum sporozoites. DEFB1 protein induction was quantified using ELISA, while parasite burden and cell viability were assessed via microscopy, RT-qPCR, and MTT assays respectively.

Transfecting HCT-8 cells with synthetic DEFB1-mRNA successfully induced a twofold increase in DEFB1 protein expression compared to controls. This induction provided significant protection against C. parvum infection. The most striking finding was:

Synthetic DEFB1-mRNA treatment achieved an approximate 80% reduction in parasite burden. Crucially, this potent anti-parasitic effect was observed with no detectable cytotoxicity to the host cells, as confirmed by MTT assays. The study effectively demonstrated that increasing endogenous DEFB1 levels via mRNA technology can significantly mitigate Cryptosporidium infection in an in vitro human intestinal model, highlighting the potential for targeted host defense mechanisms.