Influence of Cryptosporidium parvum and Giardia duodenalis on glucose transport mechanisms and tight junctions in co-infected enterocytes

BACKGROUND: Cryptosporidium parvum and Giardia duodenalis (assemblages A and B) are ubiquitously occurring protozoan parasites infecting a broad range of hosts. Co-infection with both parasites in suitable hosts have been reported, but information on structural or functional alterations in host cells caused by simultaneous infection is rare. Previous findings showing an enhanced replication of G. duodenalis during co-infection suggest synergistic effects of both parasites that were investigated in this in vitro study. METHODS: The tight junction proteins claudin (CLDN) 1, 4, 6, and 7 as well as the glucose transporters (GLUT) 1 and 2 of IPEC-J-2 cells were examined comparing single and co-infections on gene expression level after 24 h, 48 h, and 72 h post infection (p.i.). Additionally, an analysis of intracellular glucose levels was performed 48 h p.i. RESULTS: No significant changes of the gene expression of the examined tight junction proteins were observed. Regarding the glucose transporters, GLUT2 was significantly decreased in cells infected by C. parvum sporozoites compared to cells infected by G. duodenalis trophozoites 48 h p.i. (p = 0.017) as well as compared to uninfected control cells (p = 0.021). Additionally, co-infected cells showed a significantly increased intracellular glucose level (p = 0.022) and C. parvum infected cells a non-significant trend of an increased intracellular glucose level (p = 0.056) in comparison to control cells. Compared to G. duodenalis mono-infected cells, co-infected cells showed a tendency for higher intracellular glucose levels (p = 0.057). CONCLUSION: Cryptosporidium parvum had an impact on GLUT2 transcript abundance and also increased glucose levels in mono- and co-infection under the tested conditions, while G. duodenalis did not alter the examined glucose transporter and tight junctions markers in this model.