Immune Response of Amebiasis and Immune Evasion by Entamoeba histolytica

Abstract

Entamoeba histolytica is a protozoan parasite and the causative agent of amebiasis. It is estimated approximately 1% of humans are infected with E. histolytica, resulting in an estimate of 100,000 deaths annually. Clinical manifestations of amebic infection range widely from asymptomatic to severe symptoms, including dysentery and extra-intestinal abscesses. Like other infectious diseases, it is assumed that only ~20% of infected individuals develop symptoms, and genetic factors of both the parasite and humans as well as the environmental factors, e.g., microbiota, determine outcome of infection. There are multiple essential steps in amebic infection: degradation of and invasion into the mucosal layer, adherence to the intestinal epithelium, invasion into the tissues, and dissemination to other organs. While the mechanisms of invasion and destruction of the host tissues by the amebae during infection have been elucidated at the molecular levels, it remains largely uncharacterized how the parasite survive in the host by evading and attacking host immune system. Recently, the strategies for immune evasion by the parasite have been unraveled, including immunomodulation to suppress IFN-γ production, elimination of immune cells and soluble immune mediators, and metabolic alterations against reactive oxygen and nitrogen species to fend off the attack from immune system. In this review, we summarized the latest knowledge on immune reaction and immune evasion during amebiasis.

Review Article: Amebiasis Molecular Pathogenesis Development

“…EhCP5 is also associated with colon epithelial cell integrins and activates the NFkappaβ-mediated inflammatory response in host cells. Research in 2014 showed that EhCPA5 activates matrix metalloproteinase (MMP) by splitting (12,13) .…”

“…Before adherence cells, trophozoites secrete immune modulators which stimulate epithelial cells to produce proinflammatory cytokine macrophage migration inhibitory factor (EhMIF). EhMIF induces inflammation resulting in increased production of matrix metalloproteinase (MMP) (13) .…”

“…In a current study, MMP was shown to be needed for the invasion of E. histolytica tissue. MMP rupture the extracellular matrix in the intestine to increase cell migration and is shown excessively in parasitic infections, such as amebiasis (4,13) .…”

“…IECs are the second defense barrier against pathogens after the mucosal layer and first defense of host cells to fight parasites, host cells secrete an arrangement of pathogen recognition receptors (PRRs), including TLRs. IFN-γ is involved in cleaning the infection, whereas IL-4 and TNF-α are associated with disease (13) .…”

Recent advances in Entamoeba biology: RNA interference, drug discovery, and gut microbiome

“…A number of excellent reviews have recently been published on the immune response to Entamoeba 18 , immune evasion mechanisms by the parasite 19 , trogocytosis (nibbling of host cells by the amoeba) 20– 22 , and virulence determinants 23 . Thus, we will focus on topics for which recent reviews are not available.…”