Newly visualized fibrillar collagen scaffolds dictate Entamoeba histolytica invasion route in the human colon

Abstract

SummaryThe extracellular matrix (ECM) and its role in the outcome of infectious diseases have been poorly investigated. In this study, we determined the impact of the collagen fibres architecture on the invasive process of the enteric parasite Entamoeba histolytica. The behaviour of E. histolytica wild-type and silenced for the cysteine protease A5 (CP-A5) were compared on a three-dimensional collagen matrix and within human colon fragments for fibrillar collagen cleavage and migration. The interstitial collagen fibres within the connective tissue of the human colon, visualized by multiphoton and second harmonic generation signals imaging, presented a dense scaffold at the subepithelial level and a loose meshwork within the chorion. To penetrate the tissue, E. histolytica migrated on the dense scaffold that remained intact, reached the crypt of Lieberkhün, migrated along and then disorganized the loose scaffold to escape into the mucosa. Interestingly, in vitro, CP-A5 was not required for collagenase activity and migration through the matrix but was necessary within the tissue environment for collagen meshwork remodelling and subsequent invasion. The data point out that further step of invasion relay with ECM destruction that requires human components induced or activated in the presence of CP-A5.

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

“…We controlled the effect of marimastat on E. histolytica by preincubated trophozoites with marimastat 30 min prior the incubation on human colon tissue. Treatment with marimastat alone had no effect on the trophozoites' invasiveness, since marimastat-treated trophozoites subsequently invaded the tissue to the same extent as wild-type (WT) trophozoites 3,4 (Fig. 1a).…”

“…We had previously shown that intestinal invasion by E. histolytica requires collagen fibre remodelling 4 . Thus, we next looked at whether the inhibition of intestinal invasion in the presence of marimastat was correlated with a defect in collagen remodelling (as a consequence of MMP inhibition).…”

“…In previous work 4 , we demonstrated that CP-A5 cooperates with human tissue factors during trophozoite invasion of the intestinal mucosa. Given that CP-A5 induces TNF-a and IL-1b secretion (which in turn can induce MMP expression), we decided to investigate the role of the MMPs' enzymatic activities during intestinal amoebiasis.…”

“…Indeed, induction of the secretion of cytokines (particularly interleukin (IL)-1b, IL-6, IL-8, interferon-g and tumour necrosis factor (TNF)-a 3 ) appears to be the central factor in the genesis of disease. 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] .…”

“…8). Thus, trophozoites epigenetically silenced for CP-A5 (that is, CP-A5 negative) fail to trigger a host inflammatory response or induce the collagen remodelling required for invasion of the lamina propria 3,4 .…”