Azithromycin Mitigates Experimental Cryptosporidiosis-Driven Ileocecal Adenocarcinoma by Modulating Autophagy, Apoptosis, and PI3K/AKT Signaling.

Background/

Objectives

Cryptosporidium parvum (C. parvum), a waterborne intestinal parasite, causes severe, persistent infections in immunocompromised hosts and has been linked to the onset of ileocecal adenocarcinoma. However, the molecular pathways linking chronic infection to carcinogenesis remain unclear. Nitazoxanide (NTZ), the only FDA-approved drug for this infection, shows limited efficacy. In contrast, azithromycin (AZM) possesses both antiparasitic and anticancer activity, though conclusive evidence supporting its effectiveness against cryptosporidiosis is still lacking. This study aimed to investigate the therapeutic potential of AZM against chronic cryptosporidiosis and its associated tumorigenic sequelae.

Methods

Immunosuppressed mice were infected with C. parvum and treated with NTZ or AZM. Parasite burden was assessed by quantifying fecal oocyst shedding. Ileocecal tissues were analyzed for histopathology, inflammation (IL-6 and TNF-α), autophagy markers (LC3II, Beclin-1, and Atg7), PI3K/AKT signaling, and apoptotic markers (Bcl2, Bax, cleaved caspase-3, DR4, and DR5) using ELISA, real-time PCR, and Western blot.

Results

Chronic C. parvum infection induced Vienna 4.4 adenocarcinoma, activated autophagy and PI3K/AKT signaling, and suppressed intrinsic and TRAIL-mediated apoptosis. AZM significantly reduced the parasitic load by 87%, outperforming NTZ (62%). It also restored epithelial integrity, attenuated inflammation, and counteracted pro-tumorigenic effects by inhibiting autophagy, downregulating the PI3K/AKT pathway, and stimulating apoptosis.

Conclusions

AZM counteracted parasite-driven tumorigenic mechanisms by disrupting survival pathways and promoting apoptosis in infected and transformed cells. These findings provide evidence that AZM exerts dual antiparasitic effects and counteracts pro-tumorigenic signaling in chronic cryptosporidiosis, highlighting its potential as a therapeutic agent to prevent infection-associated ileocecal carcinogenesis.