Toxocara canis mucins among other excretory-secretory antigens induce in vitro secretion of cytokines by mouse splenocytes

Abstract

The effect of Toxocara larval antigens on cytokine secretion by mouse splenocytes was studied in vitro. Recombinant mucins were produced in Pichia pastoris yeast, and Toxocara excretory-secretory (TES) antigens were collected from in vitro culture of L2 larvae. Tc-MUC-2, Tc-MUC-3, Tc-MUC-4, and Tc-MUC-5 were expressed as glycoproteins and were specifically recognized by Toxocara canis-infected dog serum antibodies. Mouse splenocytes stimulated with recombinant mucins produced IL-5, IL-6, and TGF-β. Cell stimulation with whole TES products was more effective and resulted in secretion of IL-4, IL-5, IL-6, IL-10, and TGF-β and downregulation of TNF-α production. IFN-γ and IL-17 secretion was noted only after ConA treatment. Cells originating from infected animals produced significantly smaller amounts of these two cytokines compared to control cells, which suggests that Th1 and Th17 response in infected mice is strongly inhibited. However, splenocyte stimulation with both TES and ConA upregulated the production of IFN-γ and IL-17. This shows that TES antigens have strong immunomodulatory properties and are able to induce a broad range of effects on murine immune cells.

Zoonotic intestinal helminths interact with the canine immune system by modulating T cell responses and preventing dendritic cell maturation

“…Confirming the immunoregulatory potential of AcES and TcES in the definitive host on the cytokine level, we show ES antigens to enhance IL-10 secretion of canine lymphocytes. This is in accordance with previous studies on the cytokine pattern induced by larval secretions of A. caninum and T. canis in humans and/or mice showing them to be dominated by anti-inflammatory molecules including IL-10 17 , 35 , 36 . Similarly, PBMCs of dogs infected with T. canis during pregnancy are reported to show higher secretion of IL-10 39 .…”

“…Interestingly, the suppression of pro-inflammatory cytokines and the anti-proliferating effects of AcES are significantly increased in patients infected with A. caninum compared to uninfected controls 17 . Enhancing immunosuppression by inducing anti-inflammatory cytokines, such as TGF-β and/or IL-10, has also been shown for T. canis in humans and mice 14 , 35 , 36 . Its anti-inflammatory potential is further evidenced by in vivo data demonstrating Foxp3 mRNA and protein levels to be increased in T. canis -infected mice 37 .…”

“…Its anti-inflammatory potential is further evidenced by in vivo data demonstrating Foxp3 mRNA and protein levels to be increased in T. canis -infected mice 37 . In addition, murine cytokine responses in the context of T. canis infection are further predominated by high levels of Th2-related cytokines such as IL-4 and IL-5 35 , 38 .…”

Infection with Toxocara canis Inhibits the Production of IgE Antibodies to α-Gal in Humans: Towards a Conceptual Framework of the Hygiene Hypothesis?

“…The larvae release a substantial amount of immunomodulatory ES products, which help them to evade the host immune system and survive in the host tissues for years [79]. Stimulation of mouse splenocytes with T. canis ES products resulted in the secretion of regulatory IL-4, IL-5, IL-6, IL-10, and TGF-β cytokines and downregulation of proinflammatory tumor necrosis factor (TNF)-α [80]. In line with this study, the production of IL-10 and TGF-β by macrophages was two times higher in T. canis-infected mice compared to an uninfected group, while IL-12 and TNF-α production was significantly suppressed in the infected group [81].…”

Human toxocariasis – A look at a neglected disease through an epidemiological ‘prism’

“…However, for many such diseases, protective immunity is often 'blocked' by a parasite's ability to inhibit and/or evade the host immune system (McSorley and Maizels, 2012). For Toxocara species, immune evasion is mediated by surface-coat and excretory/secretory (ES) molecules (Maizels, 2013), which might be vaccine targets for protective type 2-like immune responses (Długosz et al, 2015;. TES components, originally explored by Maizels et al (1984), include the C-type lectins TES-32 and -70 and glycosylated mucins which represent a surface-coat of the larval stage (Długosz et al, 2015;Gems and Maizels, 1996;Kennedy et al, 1987;Loukas et al, 1999.…”