Immunopathological assessments of human Blastocystis spp. in experimentally infected immunocompetent and immunosuppresed mice

Abstract

Blastocystis spp., one of the most common parasites colonizing the human intestine, is an extracellular, luminal protozoan with controversial pathogenesis. The host's immune response against Blastocystis spp. infection has also not been defined yet. Therefore, this research aimed to assess the potential pathogenicity of this parasite and its ability to modulate the immune response in experimental infected immunocompetent and immunosuppresed mice. These results demonstrated that the infected immunosuppressed mice were more affected than infected immunocompetent mice. Histopathological examination of the small intestine in the infected immunosuppressed mice showed that Blastocystis spp. infiltrated all the layers. Moreover, the epithelia showed exfoliation and inflammatory cell infiltration in submucosa compared to that of the infected immunocompetent mice. As well, examination of the large intestine of the infected immunosuppressed group showed severe goblet cell hyperplasia. Blastocystis spp. infiltrated all the large intestine layers compared to that of the infected immunocompetent group. Furthermore, there was a significant upregulation of the expression of proinflammatory cytokines: interleukin 12 (IL-12) and tumor necrosis factor alpha (TNF-α) in the infected immunosuppressed mice compared to that of the infected immunocompetent ones (p ≤ 0.004 and p ≤ 0.002, respectively). However, the expression of anti-inflammatory cytokines (IL-4 and IL-10) was significantly downregulated in the infected immunosuppressed group compared to that of the infected immunocompetent group one at 10 days postinfection (p ≤ 0.002 and p ≤ 0.001, respectively). The results of this study revealed that Blastocystis spp. affected the production of pro- and anti-inflammatory cytokines in both groups of mice compared to healthy normal (naive) group. Additionally, these data showed that there was a significant upregulation (p ≤ 0.005) of the locally synthesized antibody: secretary IgA (sIgA) in the gut of the infected immunocompetent mice when compared to that of the infected immunosuppressed ones.

Exacerbation of colon carcinogenesis by Blastocystis sp.

“…was further proven with the evidence of the formation of cysteine proteases [ 22 ]. In another study, intestinal cells were found to exhibit low level of IgA and increased level of pro-inflammatory cytokines in the presence of Blastocystis infection [ 23 , 24 ]. Even though numerous in vitro studies have been carried out to associate Blastocystis with colorectal cancer, there were no studies conducted thus far using cancer-induced rat models to validate this association.…”

Preneoplastic proliferative changes induced by experimental blastocystosis

“…A similar picture with mild inflammatory reaction was noticed in mice inoculated by isolates derived from asymptomatic carriers included in our study. On the other hand, isolates from symptomatic patients have been observed, in many studies, to cause more severe and intense pathological changes with mucosal sloughing, intense inflammatory cells infiltration, and parasite infiltration of lamina propria in mice [28,30,44,49] and rats [6,27,31,55] . In addition, Hussein et al [31] and Abaza et al [6] reported the induction of a more severe degree of pathological change with polypoid projections in colonic mucosa of rats infected by symptomatic isolates, that the authors referred to as precancerous polyps.…”

Changes in the immune system in experimental acanthamoebiasis in immunocompetent and immunosuppressed hosts

“…infected immunosuppressed mice produced significantly more IFN-γ than infected immunocompetent hosts, as in previous studies on the invasion of Blastocystis spp. [ 44 ].…”