Entamoeba histolytica: Host parasite interactions at the colonic epithelium

Abstract

Entamoeba histolytica (Eh) is the protozoan parasite responsible for intestinal amebiasis and interacts dynamically with the host intestinal epithelium during disease pathogenesis. A multifaceted pathogenesis profile accounts for why 90% of individuals infected with Eh are largely asymptomatic. For 100 millions individuals that are infected each year, key interactions within the intestinal mucosa dictate disease susceptibility. The ability for Eh to induce amebic colitis and disseminate into extraintestinal organs depends on the parasite competing with indigenous bacteria and overcoming the mucus barrier, binding to host cells inducing their cell death, invasion through the mucosa and outsmarting the immune system. In this review we summarize how Eh interacts with the intestinal epithelium and subverts host defense mechanisms in disease pathogenesis.

Keywords: antimicrobial peptides; cysteine proteases; entamoeba histolytica; epithelium; inflammasome; mucus; tight junction proteins.

Figure 1.

Entamoeba histolytica interactions with the mucosal barriers (clockwise). During Eh invasion the parasite degrades the protective mucus layers and evoke mucus hypersecretion from goblet cells (GC). By interacting with epithelial cells directly, Eh induces a pro-inflammatory responses driven by NF-B and later perturbation of the tight junction proteins to stimulate water and ion secretion. The epithelial barrier is then breached by cytolysis of epithelial cells allowing Eh to migrate in the lamina propria degrading the extracellular matrix (ECM). Here, Eh interacts with the immune compartment specifically macrophages where either Eh death will occur through NO-dependent killing or Eh will establish chronic disease.