Changes in holothurian coelomocyte populations following immune stimulation with different molecular patterns

Abstract

Echinoderms possess a variety of cells populating the coelomic fluid; these cells are responsible for mounting defense against foreign agents. In the sea cucumber Holothuria glaberrima, four different coelomocyte types were readily distinguished using morphological, histochemical and physiological (phagocytic activity) parameters: lymphocytes, phagocytes, spherulocytes and “giant” cells (listed in order of abundance). Monoclonal antibodies generated against sea cucumber tissues and one polyclonal against sea urchin mayor yolk protein (MYP) were also used to characterize these cell populations. The effects of several pathogen-associated molecular patterns (PAMPs): Lipopolysaccharides from E. coli (LPS), heat-killed Staphylococcus aureus (SA) and a synthetic dsRNA were studied on coelomocyte cell populations. PAMPs increased the phagocytic activity of the holothurian coelomocytes, and were able to induce selective immune responses in several of these populations, demonstrating the ability of the sea cucumber to respond to a different variety of immune challenges. Overall, these results show the variety of cells that populate the coelomic fluid of the holothurian and demonstrate their involvement in immune reactions. These animals represent an untapped resource for new findings into the evolution and development of the immune response not only in invertebrates but also in phylogenetically shared reactions with vertebrates.

Characterization and expression analysis of a complement component gene in sea cucumber (Apostichopus japonicus)

“…Welsh found that human serum can deplete RNA virus through either the classical complement pathway component C4 or the alternative complement pathway component factor B (Welsh, 1977). Furthermore, it was reported that LPS and dsRNA could effectively increase phagocytes and phagocytic activities in coelomocytes of the sea cucumber Holothuria glaberrima (Ramírez-Gómez et al, 2010). In this study, we found that the AjBf gene expression increased significantly after LPS challenge, which was consistent with gene C3 as we reported early (Zhou et al, 2011).…”

Effects of dietary β-glucan, mannan oligosaccharide and their combinations on growth performance, immunity and resistance against Vibrio splendidus of sea cucumber, Apostichopus japonicus

“…Studies have shown that immune system of sea cucumber, Holothuria glaberrima, responds differentially to different PAMPs [22]. In the present study, dietary b-glucan and MOS showed different effects on the immune indices of A. japonicus.…”

“…The echinoderm immune system can be activated when encountering foreign molecules with pathogen-associated molecular patterns (PAMPs) including lipopolysaccharides, peptidoglycans, dsRNA, b-glucans, mannan, chitin and so on, which can be recognized and bound by pattern-recognition proteins (PRPs) [22]. The recognition and binding in turn evoke subsequent internal defense.…”

The first echinoderm gamma-interferon-inducible lysosomal thiol reductase (GILT) identified from sea cucumber (Stichopus monotuberculatus)

“…The highest expression level of StmGILT mRNA was found in the coelomocytes that are generally considered as the effector cells of echinoderm immune system [25]. The high mRNA expression level in coelomocytes of S. monotuberculatus implied that StmGILT may be an immune-related gene in this species.…”

“…In echinoderms, coelomocytes have been determined as the effector cells of immune system [25]. So, coelomocytes of sea cucumber were isolated and used as our target cells to explore the immune function of GILT in this study.…”