Major cysteine peptidases of Entamoeba histolytica are required for aggregation and digestion of erythrocytes but are dispensable for phagocytosis and cytopathogenicity

Abstract

SummaryCysteine peptidases of Entamoeba histolytica (EhCPs) are considered to be important pathogenicity factors. It has been described that under standard axenic culture conditions, only three (ehcp-a1, ehcp-a2 and ehcp-a5) out of approximately 50 cysteine peptidase genes present in the E. histolytica genome are substantially expressed, thus representing the set of major EhCPs. In this study, transcriptional silencing of the major peptidase genes was used to characterize their physiological role in more detail. Analysing the transfectants a fourth major cysteine peptidase activity belonging to EhCP-A7 could be characterized. Neither cytopathic activity nor phagocytosis of erythrocytes was altered in CP-inactivated amoebae. However, a significant difference in haemolytic activity was observed. EhCP-A1 and EhCP-A7 apparently had no influence on haemolytic activity, whereas transfectants silenced for ehcp-a5 as well as those silenced for all major peptidases showed a significant reduction in their haemolytic activity. Furthermore, cells silenced for ehcp-a1 and ehcp-a7 and more effectively cells silenced in all major ehcps were impaired in digesting of phagocytosed erythrocytes. Moreover, amoebae silenced for all major peptidase genes lost the ability to form aggregates of erythrocytes prior to phagocytosis.

The parasite Entamoeba histolytica exploits the activities of human matrix metalloproteinases to invade colonic tissue

“…Furthermore, perturbation of the extracellular matrix (ECM) is required for E. histolytica to invade the lamina propria 4 . Cysteine proteinases are major virulence factors in trophozoites [5][6][7] . The cysteine proteinase A5 (CP-A5) interacts directly with integrins at the surface of human colon epithelial cells and induces the secretion of pro-inflammatory cytokines (including TNF-a and IL-1b; ref.…”

In vivo programmed cell death of Entamoeba histolytica trophozoites in a hamster model of amoebic liver abscess

“…Hence, adherence is required for cytolysis, but this is apparently insufficient, as we demonstrated that apoptotic cell death of neutrophils and macrophages induced by E. histolytica trophozoites can occur without target cell contact. There are undoubtedly many factors involved in these processes, such as amoebapores (8 kDa; Leippe & Müller-Eberhard, 1994) and cysteine proteinases (16-96 kDa; Irmer et al, 2009). PCD processes involve the coordinated activity of a plethora of proteins that can be separated into activators, effectors, and negative regulators, such as kinases (Franklin & McCubrey, 2000).…”

Entamoeba histolyticaelectrondense granules secretion in vitro and in vivo: Ultrastructural study

“…An ion channel-forming protein known as amebapore has been mentioned in relation with damage to the target cell (Gitler and Mirelman, 1986;Gonzá lez et al, 2008;Leippe, 1997;Lynch et al, 1982;Ravdin, 1986;Xun et al, 2009;Young et al, 1982). In addition, overexpression of some cysteine proteinases detected during in vitro destruction of cell monolayers (Bruchhaus et al, 2003;Hellberg et al, 2001;Irmer et al, 2009) as well as collagenolytic and proteolytic activities (Keene et al, 1986;Muñ oz et al, 1984) have also been reported as important virulence factors.…”