Immune response to Anisakis simplex and other ascarid nematodes

Abstract

Anisakis simplex is a nematode parasite belonging to the Ascaroidea group, which includes several species of medical importance, and the immune response to A. simplex is discussed with reference to some of these. The strong Th2 reaction usually provoked by nematodes seems to occur only in the context of infection, and exposure to nonviable antigens fails to do so. This would imply either that allergic reactions to A. simplex require prior infection, or that a classical atopic response is responsible, and the cause possibly varies among patients. The antibody response to secreted and exposed surface antigens of A. simplex is strong, and should be explored as potentially a better antigen source for serodiagnosis than somatic materials, and it might also be useful in addressing the question of the role of infection in predisposing to allergic reactions. As in toxocariasis, both secreted and shed surface antigens of A. simplex could provide a focus for in¯ammatory lesions in tissue-invasive larvae. Humans respond heterogeneously to A. simplex allergens, and experience with other nematodes would indicate that this is due to genetic control of the immune repertoire by the major histocompatibility complex, a fact which, in turn, might have clinical implications. A. simplex is known to produce allergens similar to the ABA-1 of Ascaris, which represents a structurally novel class of fatty acid and vitamin A-binding protein. This and other recently described nematode proteins are known to be highly stable to thermal denaturation and can recover their structures, biochemical activities, and allergenicity upon cooling.

Anisakis simplex: from Obscure Infectious Worm to Inducer of Immune Hypersensitivity

“…A good example of this is that the possession of certain HLA alleles that are widespread in native West Africans, but not in Caucasians, appears to correlate with protection against severe malaria (112). In terms of immune responses to defined antigens of several species of nematode, there is a clear association between with MHC genetics in experimental animals (142). Further investigation of the particular susceptibilities in other populations could be extremely useful in understanding the A. simplex-induced syndromes globally.…”

“…Similarly, schistosomes have been shown to induce immune responses through TLR2, TLR3, and TLR4 (109). This new focus of research has important implications for nematode infections, particularly since nematodes appear to contain glycolipids (reviewed by Kennedy [142] and Lorenzo et al [167]) that are of types confined to them and since detection systems that recognize nematodes generically, such as TLRs, would be selectively advantageous (109). Although the TLR family is an important class of sensors for innate recognition of parasites, other non-TLR pattern recognition systems may also be involved (64).…”

“…Moreover, recent work on the cleavage of the CD23 cell surface receptor (which is involved in IgE regulation) by Dermatophagoides protease allergens has led to the idea that enzymes of the appropriate specificity could directly bias immune responses toward Th2 dominance (242,244,257). In 2000 (142,163), it was pointed out that proteases could be allergens or otherwise immunologically manipulative as a general phenomenon, but given the large quantities in which A. simplex appears to secrete proteases when it enters the mammalian host, their role in allergic reactions ought to be investigated. When serum CD23 levels were measured at intervals of 24 h, 1 month, and 6 months in gastroallergic anisakiasis patients, levels were unchanged.…”

“…In order to invade the gastrointestinal mucosa, the L3 of A. simplex probably use mechanical disruption of tissue combined with the release of potent proteolytic enzymes that are capable of degrading the extracellular matrix (142,178,182,232,234). These proteases are probably produced by the dorsal esophageal gland and the excretory cell of the A. simplex larva to be secreted through the excretory pore and the oral opening, respectively (46,179,231).…”

Endoparasitoses in hospitalised paediatric patients with pulmonary disease

“…Therefore, our observed groups of paediatric patients were selected from the comparable socio-economical environment. The value of total IgE in the serum of children infected with G. intestinalis and E. vermicularis was significantly higher compared to the control group of healthy children (Kennedy, 2000). Eosiniphilia is very frequent reaction of a host to helminth invasion, but it is rare in protozoal infections.…”