Neutrophil and eosinophil chemotactic factors in the excretory/secretory products of sheep abomasal nematode parasites

Abstract

Both eosinophil chemotactic factor (ECF) and neutrophil chemotactic factor (NCF) activities were demonstrated in excretory/secretory (ES) products and homogenates of Haemonchus contortus and Teladorsagia circumcincta larvae and adult worms in a modified checkerboard assay using a micro-chemotaxis chamber. Neutrophil chemotaxis was seen in 28 of 35 experiments and eosinophil chemotaxis in 20 of 38 experiments. Chemokinetic activity for neutrophils and eosinophils (accounting for 40-50% of total cell migration) was also apparent in only three parasite products for each cell type. Significant NCF activity was present in six of seven adult worm ES products (three of four from T. circumcincta and in all three from H. contortus) and ECF activity in four of five adult ES products, whereas fewer L3 incubates, particularly of T. circumcincta, contained chemotactic activity. All parasite homogenates, with one exception for ECF, were chemotactic for both neutrophils and eosinophils. The sequential use of cellulose ultrafiltration membranes of decreasing pore size did not identify precisely the molecular weight of the NCF and ECF but indicated that the active chemicals were greater than 10 kDa and probably greater than 30 kDa.

Tropomyosin: An Excretory/Secretory Protein from Haemonchus contortus Mediates the Immuno-Suppressive Potential of Goat Peripheral Blood Mononuclear Cells In Vitro

“…Inside the host, H. contortus secrete and excrete various proteins that mediate modulatory or suppressive potential for immune responses during host parasite interactions. These responses are governed by the interaction of these proteins through receptor-ligand systems on the surface of host cells [30,38]. In our recent study, H. contortus tropomyosin was identified in excretory and secretory (ES) protein to bind to goat PBMCs in vivo at a specific developmental stage (L4 + L5) of the parasite [20], however, the host cells-related immunoregulatory functions affected by Hc-TpMy were not highlighted yet.…”

A Trypsin-Sensitive Proteoglycan from the Tapeworm <b><i>Hymenolepis diminuta</i></b> Inhibits Murine Neutrophil Chemotaxis in vitro by Suppressing p38 MAP Kinase Activation

“…The scientific literature is replete with examples of helminth-derived excretory/secretory products, extracts or semi-purified molecules directly affecting a variety of functions of innate immune cells [25,26]. Indeed, products from nematode and trematode parasites can be chemoattractants for neutrophils in vitro [27][28][29]: thus, it was unexpected when HdE failed to elicit neutrophil chemotaxis in under-agarose or transwell systems. Contrari- NØs) migration towards WKYMVm (1 μM) in a transwell assay (8 μm pore size filter) is unaffected by a 30 min pre-treatment with LPS (1 μg/mL) or the calcium ionophore, A23187 (2.5 μM).…”

“…The suppression of neutrophil chemotaxis is intriguing, particularly since other reports on helminth-derived molecules describe them as neutrophil chemoattractants [27][28][29][30]. Schroeder et al reported that live microfilariae of Brugia malayi blocked transendothelial migration of neutrophils but did not determine if this was via the release of a molecule from the nematode [31].…”

Immune Responses Associated with Resistance to Haemonchosis in Sheep

“…After larvae activate complement, vasoactive and chemotactic peptides (C3a and C5a) are generated, and these peptides mobilize eosinophils to the area of infection independently of specific mechanisms (CD4+ and IL-5). At the same time, H. contortus secretes chemoattractants for eosinophils and neutrophils, which reinforce the inflammatory response [57]. The thymus-independent increase in tissue eosinophils is an important innate response in which complement activation mediates the cytotoxicity of eosinophils against larvae in early infection stages in the absence of specific antibodies.…”