The Effects of Intestinal Nematode L4 Stage on Mouse Experimental Autoimmune Encephalomyelitis

Modulation of LPS-Induced Neurodegeneration by Intestinal Helminth Infection in Ageing Mice

Parasitic helminths induce a transient, short-term inflammation at the beginning of infection, but in persistent infection may suppress the systemic immune response by enhancing the activity of regulatory M2 macrophages. The aim of the study was to determine how nematode infection affects age-related neuroinflammation, especially macrophages in the nervous tissue. Here, intraperitoneal LPS-induced systemic inflammation resulting in brain neurodegeneration was enhanced by prolonged Heligmosomoides polygyrus infection in C57BL/6 mice. The changes in the brain coincided with the increase in M1 macrophages, reduced survivin level, enhanced APP and GFAP expression, chitin-like chains deposition in the brain and deterioration behaviour manifestations. These changes were also observed in transgenic C57BL/6 mice predisposed to develop neurodegeneration typical for Alzheimer's disease in response to pathogenic stimuli. Interestingly, in mice infected with the nematode only, the greater M2 macrophage population resulted in better results in the forced swim test. Given the growing burden of neurodegenerative diseases, understanding such interactive associations can have significant implications for ageing health strategies and disease monitoring.

Toxocara canis infection worsens the course of experimental autoimmune encephalomyelitis in mice

Toxocara canis, a gastrointestinal parasite of canids, is also highly prevalent in many paratenic hosts, such as mice and humans. As with many other helminths, the infection is associated with immunomodulatory effects, which could affect other inflammatory conditions including autoimmune and allergic diseases. Here, we investigated the effect of T. canis infection on the course of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Mice infected with 2 doses of 100 T. canis L3 larvae 5 weeks prior to EAE induction (the Tc+EAE group) showed higher EAE clinical scores and greater weight loss compared to the non-infected group with induced EAE (the EAE group). Elevated concentrations of all measured serum cytokines (IL-1α, IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ and TNF-α) were observed in the Tc+EAE group compared to the EAE group. In the CNS, the similar number of regulatory T cells (Tregs; CD4+FoxP3+Helios+) but their decreased proportion from total CD4+ cells was found in the Tc+EAE group compared to the EAE group. This could indicate that the group Tc+EAE harboured significantly more CD4+ T cells of non-Treg phenotype within the affected CNS. Altogether, our results demonstrate that infection of mice with T. canis worsens the course of subsequently induced EAE. Further studies are, therefore, urgently needed to reveal the underlying pathological mechanisms and to investigate possible risks for the human population, in which exposure to T. canis is frequent.

Reduced Expression of PD-1 in Circulating CD4+ and CD8+ Tregs Is an Early Feature of RRMS

Altered regulatory T cell (Treg) function could contribute to MS. The expression of activating and inhibitory receptors influences the activity of Tregs. Our aim was to investigate T cell phenotypes in relapsing-remitting MS (RRMS) patients at an early phase of the disease. We examined the influence of demographic parameters on the distribution of CD4+ and CD8+ T cell subclasses by generalized linear modeling. We also studied the expression of the following markers-CTLA-4, GITR, PD-1, FoxP3, Helios, CD28, CD62L, CD103-on T cell subsets from peripheral blood with a 14-color flow cytometry panel. We used an antibody array to define the profiles of 34 Th1/Th2/Th17 cytokines in the serum. Expression of PD-1 and GITR on CD4+ and CD8+ Tregs was decreased in RRMS patients. The proinflammatory factors IFN-γ, IL-17, IL-17F, TGFβ-1, TGFβ-3, IL-1SRII, IL-12 p40, sgp130, IL-6sR were significantly increased in RRMS patients. Therefore, a deficiency of PD-1 and GITR immune checkpoints on CD4+ and CD8+ Tregs is a feature of RRMS and might underlie impaired T cell control.

Remote regulation of type 2 immunity by intestinal parasites

The intestinal tract is the target organ of most parasitic infections, including those by helminths and protozoa. These parasites elicit prototypical type 2 immune activation in the host's immune system with striking impact on the local tissue microenvironment. Despite local containment of these parasites within the intestinal tract, parasitic infections also mediate immune adaptation in peripheral organs. In this review, we summarize the current knowledge on how such gut-tissue axes influence important immune-mediated resistance and disease tolerance in the context of coinfections, and elaborate on the implications of parasite-regulated gut-lung and gut-brain axes on the development and severity of airway inflammation and central nervous system diseases.

Calendula officinalis Triterpenoid Saponins Impact the Immune Recognition of Proteins in Parasitic Nematodes

The influence of triterpenoid saponins on subcellular morphological changes in the cells of parasitic nematodes remains poorly understood. Our study examines the effect of oleanolic acid glucuronides from marigold (Calendula officinalis) on the possible modification of immunogenic proteins from infective Heligmosomoides polygyrus bakeri larvae (L3). Our findings indicate that the triterpenoid saponins alter the subcellular morphology of the larvae and prevent recognition of nematode-specific proteins by rabbit immune-IgG. TEM ultrastructure and HPLC analysis showed that microtubule and cytoskeleton fibres were fragmented by saponin treatment. MASCOT bioinformatic analysis revealed that in larvae exposed to saponins, the immune epitopes of their proteins altered. Several mitochondrial and cytoskeleton proteins involved in signalling and cellular processes were downregulated or degraded. As possible candidates, the following set of recognised proteins may play a key role in the immunogenicity of larvae: beta-tubulin isotype, alpha-tubulin, myosin, paramyosin isoform-1, actin, disorganized muscle protein-1, ATP-synthase, beta subunit, carboxyl transferase domain protein, glutamate dehydrogenase, enolase (phosphopyruvate hydratase), fructose-bisphosphate aldolase 2, tropomyosin, arginine kinase or putative chaperone protein DnaK, and galactoside-binding lectin. Data are available via ProteomeXchange with identifier PXD024205.

The production of excretory-secretory molecules from Heligmosomoides polygyrus bakeri fourth stage larvae varies between mixed and single sex cultures

Background

Excretory-secretory (ES) products are crucial in maintaining helminths in the host. Consequently, the proteins of ES are potential vaccine molecules and potential therapeutic agents for autoimmune diseases. Heligmosomoides polygyrus bakeri, a gastrointestinal parasite of mice, is a model of hookworm infection in humans. ES produced by both sexes of H. polygyrus bakeri L4 stage cultured separately shows different immunomodulatory properties than ES obtained when both sexes are cultured together. Accordingly, the objective of this study was to identify and compare the excretory-secretory molecules from single-sex and mixed cultures.

Methods

The composition of ES of male and female L4 stage nematodes in the presence (cultured together) or absence (cultured alone) of the opposite sex was examined. Proteins were identified using mass spectrometry. The functions of identified proteins were explored with Blast2GO.

Results

A total of 258 proteins derived from mixed larval culture in the presence of sex pheromones were identified, 160 proteins from pure female cultures and 172 from pure male cultures. Exposure of nematodes to the sex pheromones results in abundant production of proteins with immunomodulatory properties such as Val proteins, acetylcholinesterases, TGF-β mimic 9 and HpARI. Proteins found only in ES from mixed larval cultures were TGF-β mimics 6 and 7 as well as galectin.

Conclusions

The presence of the opposite sex strongly influences the composition of ES products, probably by chemical (pheromone) communication between individuals. However, examination of the composition of ES from various conditions gives an opportunity for searching for new potentially therapeutic compounds and anthelminthics as well as components of vaccines. Manipulation of the nematode environment might be important for the studies on the immunomodulatory potential of nematodes.

The Helminth Parasite Heligmosomoides polygyrus Attenuates EAE in an IL-4Rα-Dependent Manner

Helminth parasites are effective in biasing Th2 immunity and inducing regulatory pathways that minimize excessive inflammation within their hosts, thus allowing chronic infection to occur whilst also suppressing bystander atopic or autoimmune diseases. Multiple sclerosis (MS) is a severe autoimmune disease characterized by inflammatory lesions within the central nervous system; there are very limited therapeutic options for the progressive forms of the disease and none are curative. Here, we used the experimental autoimmune encephalomyelitis (EAE) model to examine if the intestinal helminth Heligmosomoides polygyrus and its excretory/secretory products (HES) are able to suppress inflammatory disease. Mice infected with H. polygyrus at the time of immunization with the peptide used to induce EAE (myelin-oligodendrocyte glycoprotein, pMOG), showed a delay in the onset and peak severity of EAE disease, however, treatment with HES only showed a marginal delay in disease onset. Mice that received H. polygyrus 4 weeks prior to EAE induction were also not significantly protected. H. polygyrus secretes a known TGF-β mimic (Hp-TGM) and simultaneous H. polygyrus infection with pMOG immunization led to a significant expansion of Tregs; however, administering the recombinant Hp-TGM to EAE mice failed to replicate the EAE protection seen during infection, indicating that this may not be central to the disease protecting mechanism. Mice infected with H. polygyrus also showed a systemic Th2 biasing, and restimulating splenocytes with pMOG showed release of pMOG-specific IL-4 as well as suppression of inflammatory IL-17A. Notably, a Th2-skewed response was found only in mice infected with H. polygyrus at the time of EAE induction and not those with a chronic infection. Furthermore, H. polygyrus failed to protect against disease in IL-4Rα^−/− mice. Together these results indicate that the EAE disease protective mechanism of H. polygyrus is likely to be predominantly Th2 deviation, and further highlights Th2-biasing as a future therapeutic strategy for MS.

A critical analysis of helminth immunotherapy in multiple sclerosis

Helminthic worms are ancestral members of the intestinal ecosystem that have been largely eradicated from the general population in industrialized countries. Immunomodulatory mechanisms induced by some helminths mediate a “truce” between the mammalian host and the colonizing worm, thus allowing for long-term persistence in the absence of immune-mediated collateral tissue damage. This concept and the geographic discrepancy between global burdens of chronic inflammatory diseases and helminth infection have sparked interest in the potential of using helminthic worms as a therapeutic intervention to limit the progression of autoimmune diseases such as multiple sclerosis (MS). Here, we present and evaluate the evidence for this hypothesis in the pre-clinical animal model of MS, experimental autoimmune encephalitis, in helminth-infected MS patients and in clinical trials of administered helminth immunotherapy (HIT).

Molecular cloning and characterization of plerocercoid-immunosuppressive factor from Spirometra erinaceieuropaei

A platyhelminth, Spirometra erinaceieuropaei, belonging to the class Cestoda, causes human sparganosis, and infection with its larva results in subtle inflammation in the body of its host. We previously reported the purification of a glycoprotein, plerocercoid-immunosuppressive factor (P-ISF) from the excretory/secretory products of S. erinaceieuropaei plerocercoids that may be involved in immuno-modification. We determined the sequence of P-ISF from the N-terminal and the internal 10 amino acids of P-ISF using degenerate PCR and 5'- and 3'-RACE methods. The putative gene encoding P-ISF was 1443 bp long and the gene contained 10 exons and 9 introns in a genomic DNA of size 5205 bp. P-ISF consists of 480 amino acids including the N-terminal signal peptide sequence, and has two unknown domains,-cestoda cysteine-rich domains (CCDs) and a fibronectin type III domain between the two CCDs. All cysteine residues were conserved in the two CCDs, which shared 62% amino acid identities. Homologous analysis revealed that the CCDs were homologous with an unknown protein of Diphyllobothrium latum. To produce specific antibodies, we expressed recombinant P-ISF (rP-ISF) using wheat germ protein synthetic system. P-ISF was localized in the sub-cutaneous tissues and the parenchymal tissues of plerocercoids. Transcription of P-ISF was detected only in plerocercoid stage, but not in adult stage. Western blotting also showed a band in plerocercoide stage but not in adult. The rP-ISF did not suppress nitrite production in RAW 264.7 cells stimulated with LPS, and this might be due to lack of carbohydrate chains in the recombinant protein.

Effects of intestinal nematode treatment on CD11b activation state in an EAE mouse model of multiple sclerosis

The experimental autoimmune encephalomyelitis (EAE) animal model of Multiple Sclerosis (MS) is characterized by episodic neurologic dysfunction arising as a consequence of perivascular mononuclear cell infiltration and demyelination in the CNS. Leukocyte integrins, which are responsible for migration through the endothelial, play key roles in the pathogenesis of autoimmune diseases and chronic inflammation. Intestinal infection of mice with Heligmosomoides polygyrus appears to target CD11b (integrin αM), which is highly expressed on myeloid cells and is critical for their migration and function. H. polygyrus infection induces suppression of ongoing experimental EAE and extensive infiltration of CD11b⁺ cells to the CNS. Therefore, the aim of the present study was to characterize the phenotype and activity of CD11b⁺ cells accompanying the tissue phase infection of L4 H. polygyrus in EAE mice. It was found that the cells displayed a CD11b⁺ state with a distinct phenotype characterised by the expression of co-stimulatory CD80/CD86, CD40, MHCII, F4/80 and the mannose receptor CD206. This activation state illustrates the heterogeneity of CD11b⁺ cells in EAE mice following nematode invasion; these may have important consequences for understanding the effects of CD11b integrin, which is involved in the downregulation of neuroinflammatory disorders.