The inflammatory response of fish to helminth parasites

Abstract

Summary :Fish serve as a good model for studying vertebrate immune systems because they have a relatively simple system. Descriptions of histopathological effects of helminth parasites on fish are few and far between with limited observations made on the identification of the inflammatory cells involved in the host reaction. Recently, two cell types found within teleosts received a great deal of attention, namely mast cells and rodlet cells. Fish mast cells also known as eosinophilic granule cells, are morphologically and functionally similar to their mammalian counterparts. Acute tissue damage causes mast cells degranulation and the release of mediators of inflammation, whereas, an increase in the number of these cells is usually found in chronically inflamed tissues. Rodlet cells, however, are exclusive to fish and are characterized by a distinct cell cortex and conspicuous inclusions, called rodlets, which accounts for their name. Piscidin has also been encountered within rodlet cells. As important cell types within the immune system of fish, both mast cells and rodlet cells have been seen to increase in number in infected fish, notably at the sites of pathogen attachment or infection. The present survey will provide data from studies with the light microscope on the response of mast cells and rodlet cells in a range of fish species (Anguilla anguilla, Oncorhynchus mykiss, Salmo trutta, Coregonus lavaretus) infected with a range of different parasite genera including representatives from the Digenea, Cestoda, Nematoda and Acanthocephala. frino et al., 1999; Dezfuli et al., 2000a Dezfuli et al., , 2002a Dezfuli et al., , b, 2003b Bosi et al., 2005). The cellular involvement in the inflammatory response in teleostean fish could be biphasic, initiating with an influx of neutrophils followed by latter arrival of monocytes/macrophages (Reite & Evensen, 2006). In fish, two inflammatory cell types, namely mast cells and rodlet cells (RCs) are closely linked to other piscine inflammatory cells (Reite, 1997; Dezfuli et al., 2000b). Mast cells are found mainly in the connective tissue distributed throughput the body, and are more frequently found in tegumentary, urinary, respiratory, reproductive and gastrointestinal systems (Rocha & Chiarini-Garcia, 2007). These cells have been noticed in all vertebrates, fish (Roberts et al., 1971;Reite, 1996), amphibians (Chiu & Lagunoff, 1972), reptiles (Sottovia-Filho & Taga, 1973), birds (Selye, 1965) and mammals (Galli, 1990; Chiarini-Garcia & Pereira, 1999). Nevertheless, there is some controversy in the literature about mast cells existence in fish despite the fact that early reviews of the mast cells left little doubt that this cell type was present in all groups of vertebrates (Reite & Evensen, 2006). In fish parasitized with helminths, greater number of mast cells was noticed in site of infection (Reite, 1997; Dezfuli et al., 2000b;Reite & Evensen, 2006). Regarding rodlet cells (RCs), they are characterized by a thick fibrous capsule, a basal nucleus, and conspicuous in...

Light and electron microscopic studies on turbot Psetta maxima infected with Enteromyxum scophthalmi: histopathology of turbot enteromyxosis

“…An interesting finding was the initial increase in the amount of both rodlet and goblet cells, followed by a decrease in their number in fish suffering severe infections (Vigliano et al 2004). Such cell types are accepted to be involved in fish response to different pathogens, and the modification in their relative number has been described for several fish species suffering diverse infections or parasitic diseases (Dezfuli et al 2008, Reite 2005, Mazon et al 2007, Fleurance et al 2008. The low number of mucous and rodlet cells found in fish with severe infections may simply be attributed to the serious damage of the epithelium, which becomes unable to support these cells.…”

Eosinophils in the zebrafish: prospective isolation, characterization, and eosinophilia induction by helminth determinants

“…10 Furthermore, infection using fluorescently labeled bacteria allows disease dissemination to be imaged directly in translucent zebrafish embryos. 11 Given that teleosts in general are susceptible to infection by helminths, 12,13 we set out to describe and delineate the features and functions of zebrafish eosinophils to assess their participation in immune responses known to involve eosinophils in mammals. Here we show that expression of a gata2:eGFP transgene, in combination with light-scatter characteristics, can be used to isolate pure populations of zebrafish eosinophils.…”

Eosinophilic granule cells in Carassius auratus scale epidermis

“…Fish EGCs have been described in the literature in significant detail with respect to tissue location, histochemistry and ultrastructure (Reite 1996(Reite , 1997(Reite , 1998Evensen 1994, 2006;Dezfuli et al 2008Dezfuli et al , 2011. EGCs are increasingly recognized as the teleost counterpart of the mammalian mast cell (Dezfuli et al 2010(Dezfuli et al , 2011 with similarities between the two having been pointed out in several previous studies (Ellis 1977(Ellis , 1985Reite 1996Reite , 1997Reite , 1998Evensen 1994, 2006).…”

“…There is very little in the way of reports directly examining fish mast cell motility in a native environment, and the migratory activity of EGCs has been inferred from histological and ultrastructural analysis where these cells have accumulated at sites of infection and inflammation (Reite 1997(Reite , 1998Dezfuli et al 2008Dezfuli et al , 2011. The study by Barnett et al (1996) utilizing tilapia gill in situ is the only one available that directly demonstrates EGC motility.…”