Increased levels of anti-Encephalitozoon intestinalis antibodies in patients with colorectal cancer.

Background: The prevalence of microsporidiosis in the general population, or within specific groups of individuals/patients, is largely underestimated. The absence of specific seroprevalence tools limits knowledge of the epidemiology of these opportunistic pathogens, although known since the 1980s. Since microsporidia hijack the machinery of its host cell and certain species multiply within intestinal cells, a potential link between the parasite and colorectal cancer (CRC) has been suggested.

Methodology/principal Findings: To explore a potential epidemiological link between microsporidia and CRC, we evaluated the seroprevalence of Encephalitozoon intestinalis among CRC patients and healthy subjects using ELISA assays based on two recombinant proteins, namely rEiPTP1 and rEiSWP1, targeting polar tube and spore wall proteins. ELISA were performed in 141 CRC patients and 135 healthy controls. Patients with CRC had significantly higher anti-rEiPTP1 IgG levels than subjects in the control group. Anti-rEiPTP1 IgG, anti-rEiSWP1 IgG and anti-rEiPTP1 IgA levels were significantly increased among men with CRC compared to healthy men. Women with CRC who had died had higher rEiSWP1 IgG levels than those who were still alive.

Conclusions/significance: These higher antibody levels against microsporidia in patients with CRC suggest a relationship between microsporidia and pathophysiology of CRC.