Induction of tolerogenic properties by Anisakis larval antigens on murine dendritic cells

Anisakis simplex: Immunomodulatory effects of larval antigens on the activation of Toll like Receptors

AIMS

The objective of this investigation is to evaluate the mechanisms Anisakis simplex employs to modify its host immune system, regarding the larval antigens interactions with Toll-Like-Receptors (TLRs).

METHODS AND RESULTS

In a previous study, we described that the stimulation of bone marrow derived dendritic cells (BMDCs) with A. simplex larval antigens drive an acute inflammatory response in BALB/c mice, but a more discrete and longer response in C57BL/6J. Moreover, when A. simplex larval antigens were combined with TLR agonists (TLR 1/2-9), they modified mainly TLR2, TLR4 and TLR9 agonists responses in both mice strains, and also TLR3, TLR5 and TLR7 in BALB/c. Antigen-presenting ability was analyzed by the detection of CD11c + cells expressing surface markers (CD80-86, MHC I-II), intracellular cytokines (IL-10, IL-12, TNF-α) and intracellular proteins (Myd88, NF-κβ) by Flow Cytometry. Secreted IL-10 was measured by ELISA.

CONCLUSION

Our findings confirm not only that the host genetic basis plays a role in the development of a Th2/Th1/Treg response, but also it states A. simplex larval antigens present specific mechanisms to modify the innate response of the host. As allergies share common pathways with the immune response against this particular helminth, our results provide a better understanding into the specific mechanisms of A. simplex allergy related diseases.

Expansion of T regulatory lymphocytes by murine bone marrow dendritic cells previously stimulated with Anisakis simplex larval antigens

BACKGROUND

Anisakis simplex antigens present immunomodulatory properties by the induction of tolerogenic dendritic cells (DCs) in mice.

OBJECTIVES

To study the capacity of DCs stimulated with A. simplex excretory-secretory (ES) or crude extract (CE) to generate T_regs. To investigate in vitro effects of antigens on the metabolic activity of splenocytes induced by LPS or CpG.

METHODS

Phenotypic and functional characterization of T cells co-cultured with A. simplex-pulsed DCs was performed by flow cytometry. Lymphocyte mitochondrial respiratory activity was estimated by the Alamar Blue^® Assay.

FINDINGS

In C57BL/6J, CD4⁺CD25^-Foxp3⁺ and CD8⁺CD25^-Foxp3⁺ populations increased by CE-stimulated-DCs. In BALB/c, CE-stimulated-DCs caused the expansion of CD4⁺CD25⁺Foxp3⁺IL-10+ and CD8⁺CD25⁺Foxp3⁺IL-10+. IFN-γ expression raised in BALB/c CD4⁺CD25⁺ and CD4⁺CD25^- for CE and ES, respectively. ES-stimulated-DCs increased CD4⁺CD25⁺ Foxp3⁺ and CD8⁺CD25^- Foxp3⁺ expression in T cells. The association of ES or CE with LPS produced the increase in splenocyte activity in C57BL/6J. The association of CE with CpG decreased the proliferation caused by CpG in C57BL/6J.

MAIN CONCLUSIONS

A. simplex increase the frequency of T_regs, which in turn produce IL-10 and IFN-γ. The host genetic base is essential in the development of anti-Anisakis immune responses (Th2, Th1, T_reg).

Modulation by Anisakis simplex antigen of inflammatory response generated in experimental autoimmune encephalomyelitis

The impact of immunization with Anisakis simplex larval antigen on the occurrence and progression of experimental autoimmune encephalomyelitis (EAE) induced in mice was studied. C57BL/6J mice were immunized with the MOG_35-55 peptide and one batch was treated with A. simplex total larval antigen on days 1, 8, 10 and 12 after EAE induction. Significantly higher values were obtained in the EAE clinical parameters of the antigen-treated group. Likewise, there was a significant decrease in the weights of the animals. Anisakis-treatment produced a significant decrease in anti-MOG_35-55 specific IgG1 on day 21. On day 14 there was an increase in serum IL-2, IL-6, IL-10, IL-17A, and TGF-β in the treated group. On day 21, a decrease in IL-4, IL-6, TNF-α, TGF-β was observed. All brain determinations were made on day 21. The treatment decreased values of IL-6, IL-10, IL-17A and TNF-α. A. simplex antigen caused a significantly higher incidence of EAE and an advance in the appearance of the disease manifestations. However, treatment with the antigen was able to cause a decrease in proinflammatory cytokines (IL-6, IL-17A, and TNF-α) in nervous tissue that could establish a future preventive scenario for myelin damage.

Comparative Transcriptomics Reveals Clues for Differences in Pathogenicity between Hysterothylacium aduncum, Anisakis simplex sensu stricto and Anisakis pegreffii

Ascaridoid nematodes are widespread in marine fishes. Despite their major socioeconomic importance, mechanisms associated to the fish-borne zoonotic disease anisakiasis are still obscure. RNA-Seq and de-novo assembly were herein applied to RNA extracted from larvae and dissected pharynx of Hysterothylacium aduncum (HA), a non-pathogenic nematode. Assembled transcripts in HA were annotated and compared to the transcriptomes of the zoonotic species Anisakis simplex sensu stricto (AS) and Anisakis pegreffii (AP). Approximately 60,000,000 single-end reads were generated for HA, AS and AP. Transcripts in HA encoded for 30,254 putative peptides while AS and AP encoded for 20,574 and 20,840 putative peptides, respectively. Differential gene expression analyses yielded 471, 612 and 526 transcripts up regulated in the pharynx of HA, AS and AP. The transcriptomes of larvae and pharynx of HA were enriched in transcripts encoding collagen, peptidases, ribosomal proteins and in heat-shock motifs. Transcripts encoding proteolytic enzymes, anesthetics, inhibitors of primary hemostasis and virulence factors, anticoagulants and immunomodulatory peptides were up-regulated in AS and AP pharynx. This study represents the first transcriptomic characterization of a marine parasitic nematode commonly recovered in fish and probably of negligible concern for public health.