Downregulation of <scp>HNF4α</scp> Mediates Microvillus Damage During <scp> <i>Cryptosporidium parvum</i> </scp> Infection

Cryptosporidium is a significant zoonotic protozoan parasite that primarily infects intestinal epithelial cells, causing microvillus damage and other gastrointestinal malfunctions. However, the precise molecular mechanisms underlying this process have yet to be elucidated. In this study, IFN-γ knockout mice were infected with a virulent Cryptosporidium parvum IId isolate, and intestinal pathological changes and microvillus alterations were monitored throughout the infection. The results showed that C. parvum invasion induced both intestinal and microvillus damage in the host. Ileum tissues were collected at the early, peak, and late stages of infection for transcriptome sequencing and analysis. Differential expression and enrichment analyses revealed significant downregulation of genes associated with microvilli, lipid metabolism, and fatty acid metabolism during the peak and late stages of infection. A gene co-expression network constructed using the Pearson correlation coefficient further identified that two epithelial cell transcription factors, HNF4α and HNF4γ, were downregulated after C. parvum infection, along with multiple microvillus-related genes showing at least a two-fold decrease in expression, such as Vil1, Cdhr2, and Ush1c. The role of HNF4α in C. parvum-induced microvillus damage was validated in vitro. Activation of HNF4α using an agonist promoted C. parvum growth in Caco-2 cells. These findings reveal that C. parvum infection interferes with HNF4α expression, leading to reduced expression of brush border and related genes and ultimately resulting in microvillus damage. This study provides new insights and directions for further research on the interaction between C. parvum and the host. Elucidating this HNF4α mediated mechanism not only deepens our understanding of host-parasite interactions but also highlights potential therapeutic targets for alleviating Cryptosporidium-induced intestinal injury.