The parasitic helminth product ES-62 suppresses pathogenesis in collagen-induced arthritis by targeting the interleukin-17-producing cellular network at multiple sites

Undenatured type II collagen protects against collagen-induced arthritis by restoring gut-joint homeostasis and immunity

Oral administration of harmless antigens can induce suppression of reactive immune responses, a process that capitalises on the ability of the gastrointestinal tract to tolerate exposure to food and commensal microbiome without triggering inflammatory responses. Repeating exposure to type II collagen induces oral tolerance and inhibits induction of arthritis, a chronic inflammatory joint condition. Although some mechanisms underlying oral tolerance are described, how dysregulation of gut immune networks impacts on inflammation of distant tissues like the joints is unclear. We used undenatured type II collagen in a prophylactic regime -7.33 mg/kg three times/week- to describe the mechanisms associated with protective oral immune-therapy (OIT) in gut and joint during experimental Collagen-Induced Arthritis (CIA). OIT reduced disease incidence to 50%, with reduced expression of IL-17 and IL-22 in the joints of asymptomatic mice. Moreover, whilst the gut tissue of arthritic mice shows substantial damage and activation of tissue-specific immune networks, oral administration of undenatured type II collagen protects against gut pathology in all mice, symptomatic and asymptomatic, rewiring IL-17/IL-22 networks. Furthermore, gut fucosylation and microbiome composition were also modulated. These results corroborate the relevance of the gut-joint axis in arthritis, showing novel regulatory mechanisms linked to therapeutic OIT in joint disease.

Trichinella spiralis Paramyosin Alleviates Collagen-Induced Arthritis in Mice by Modulating CD4+ T Cell Differentiation

Rheumatoid arthritis (RA) is an autoimmune disease that significantly impacts quality of life by disrupting CD4+ T cell immune homeostasis. The identification of a low-side-effect drug for RA treatment is urgently needed. Our previous study suggests that Trichinella spiralis paramyosin (Ts-Pmy) has immunomodulatory effects, but its potential effect on CD4+ T cell response in RA remains unclear. In this study, we used a murine model to investigate the role of rTs-Pmy in regulating CD4+ T cell differentiation in collagen-induced arthritis (CIA). Additionally, we assessed the impact of rTs-Pmy on CD4+ T cell differentiation towards the Th1 and Th17 phenotypes, which are associated with inflammatory responses in arthritis, using in vitro assays. The results demonstrated that rTs-Pmy administration reduced arthritis severity by inhibiting Th1 and Th17 response while enhancing Treg response. Prophylactic administration of Ts-Pmy showed superior efficacy on CIA compared to therapeutic administration. Furthermore, in vitro assays demonstrated that rTs-Pmy could inhibit the differentiation of CD4+ T cells into Th1 and Th17 while inducing the production of Tregs, suggesting a potential mechanism underlying its therapeutic effects. This study suggests that Ts-Pmy may ameliorate CIA by restoring the immune balance of CD4+ T cells and provides new insights into the mechanism through which helminth-derived proteins exert their effects on autoimmune diseases.

Differentiation and Regulation of Bovine Th2 Cells In Vitro

Bovine Th2 cells have usually been characterized by IL4 mRNA expression, but it is unclear whether their IL4 protein expression corresponds to transcription. We found that grass-fed healthy beef cattle, which had been regularly exposed to parasites on the grass, had a low frequency of IL4+ Th2 cells during flow cytometry, similar to animals grown in feedlots. To assess the distribution of IL4+ CD4+ T cells across tissues, samples from the blood, spleen, abomasal (draining), and inguinal lymph nodes were examined, which revealed limited IL4 protein detection in the CD4+ T cells across the examined tissues. To determine if bovine CD4+ T cells may develop into Th2 cells, naïve cells were stimulated with anti-bovine CD3 under a Th2 differentiation kit in vitro. The cells produced primarily IFNγ proteins, with only a small fraction (<10%) co-expressing IL4 proteins. Quantitative PCR confirmed elevated IFNγ transcription but no significant change in IL4 transcription. Surprisingly, GATA3, the master regulator of IL4, was highest in naïve CD4+ T cells but was considerably reduced following differentiation. To determine if the differentiated cells were true Th2 cells, an unbiased proteomic assay was carried out. The assay identified 4212 proteins, 422 of which were differently expressed compared to those in naïve cells. Based on these differential proteins, Th2-related upstream components were predicted, including CD3, CD28, IL4, and IL33, demonstrating typical Th2 differentiation. To boost IL4 expression, T cell receptor (TCR) stimulation strength was reduced by lowering anti-CD3 concentrations. Consequently, weak TCR stimulation essentially abolished Th2 expansion and survival. In addition, extra recombinant bovine IL4 (rbIL4) was added during Th2 differentiation, but, despite enhanced expansion, the IL4 level remained unaltered. These findings suggest that, while bovine CD4+ T cells can respond to Th2 differentiation stimuli, the bovine IL4 pathway is not regulated in the same way as in mice and humans. Furthermore, Ostertagia ostertagi (OO) extract, a gastrointestinal nematode in cattle, inhibited signaling via CD3, CD28, IL4, and TLRs/MYD88, indicating that external pathogens can influence bovine Th2 differentiation. In conclusion, though bovine CD4+ T cells can respond to IL4-driven differentiation, IL4 expression is not a defining feature of differentiated bovine Th2 cells.

The parasitic worm product ES-62 protects against collagen-induced arthritis by resetting the gut-bone marrow axis in a microbiome-dependent manner

The parasitic worm-derived immunomodulator, ES-62 rescues defective levels of IL-10-producing regulatory B cells (Bregs) and suppresses chronic Th1/Th17-driven inflammation to protect against joint destruction in the mouse collagen-induced arthritis (CIA) model of rheumatoid arthritis. Such autoimmune arthritis is also associated with dysbiosis of the gut microbiota and disruption of intestinal barrier integrity. We recently further exploited the CIA model to show that ES-62's prevention of joint destruction is associated with protection of intestinal barrier integrity and normalization of the gut microbiota, thereby suppressing the gut pathology that precedes the onset of autoimmunity and joint damage in CIA-mice. As the status of the gut microbiota impacts on immune responses by influencing haematopoiesis, we have therefore investigated whether ES-62 harnesses the homeostatic mechanisms regulating this gut-bone marrow (BM) axis to resolve the chronic inflammation promoting autoimmunity and joint destruction in CIA. Reflecting this, ES-62 was found to counteract the BM myeloid/lymphoid bias typically associated with chronic inflammation and infection. This was achieved primarily by ES-62 acting to maintain the levels of lymphoid lineages (B220+ and CD3+ cells) observed in naïve, healthy mice but lost from the BM of CIA-mice. Moreover, ES-62's ability to prevent bone-destroying osteoclastogenesis was found to be associated with its suppression of CIA-induced upregulation of osteoclast progenitors (OCPs) in the BM. Critically, and supporting ES-62's targeting of the gut-BM axis, this rewiring of inflammatory haematopoiesis was lost in mice with a depleted microbiome. Underlining the importance of ES-62's actions in restoring steady-state haematopoiesis, the BM levels of B and T lymphoid cells were shown to be inversely correlated, whilst the levels of OCPs positively correlated, with the severity of joint damage in CIA-mice.

Protection against lung pathology during obesity-accelerated ageing in mice by the parasitic worm product ES-62

Mice develop pathology in the lungs as they age and this may be accelerated by a high calorie diet (HCD). ES-62 is a protein secreted by the parasitic worm Acanthocheilonema viteae that is immunomodulatory by virtue of covalently attached phosphorylcholine (PC) moieties. In this study, we show that weekly treatment of C57BL/6J mice with ES-62 protected against pathology in the lungs in male but not female mice fed a HCD from 10 weeks of age as shown by reductions in cellular infiltration and airway remodelling, particularly up to 160 days of age. ES-62 also reduced gene expression of the cytokines IL-4 and IL-17 and in addition the TLR/IL-1R adaptor MyD88, in the lungs of male mice although HCD-induced increases in these inflammatory markers were not detected until between 340 and 500 days of age. A combination of two drug-like ES-62 PC-based small molecule analogues (SMAs), produced broadly similar protective effects in the lungs of male mice with respect to both lung pathology and inflammatory markers, in addition to a decrease in HCD-induced IL-5 expression. Overall, our data show that ES-62 and its SMAs offer protection against HCD-accelerated pathological changes in the lungs during ageing. Given the targeting of Th2 cytokines and IL-17, we discuss this protection in the context of ES-62's previously described amelioration of airway hyper-responsiveness in mouse models of asthma.

Conquering rheumatic diseases: are parasitic worms the answer?

Despite the introduction of novel treatment strategies, management of rheumatic disorders remains associated with substantial unmet clinical need. Of interest therefore, it has recently become apparent that there is a global inverse relationship between the incidence of such conditions and parasitic helminth infection, with striking examples involving rheumatoid arthritis (RA)/systemic lupus erythematosus (SLE) patients and filarial nematode worm infection in studies in India. Such findings reflect that helminths are master manipulators of the immune system, particularly in being able to modulate proinflammatory responses. The aim of this article is thus to consider findings to date on this exciting and intriguing research area to form an opinion on whether parasitic worms may be exploited to generate novel therapies for rheumatic diseases.

Extracellular vesicles secreted by Brugia malayi microfilariae modulate the melanization pathway in the mosquito host

Vector-borne, filarial nematode diseases cause significant disease burdens in humans and domestic animals worldwide. Although there is strong direct evidence of parasite-driven immunomodulation of mammalian host responses, there is less evidence of parasite immunomodulation of the vector host. We have previously reported that all life stages of Brugia malayi, a filarial nematode and causative agent of Lymphatic filariasis, secrete extracellular vesicles (EVs). Here we investigate the immunomodulatory effects of microfilariae-derived EVs on the vector host Aedes aegypti. RNA-seq analysis of an Ae. aegypti cell line treated with B. malayi microfilariae EVs showed differential expression of both mRNAs and miRNAs. AAEL002590, an Ae. aegypti gene encoding a serine protease, was shown to be downregulated when cells were treated with biologically relevant EV concentrations in vitro. Injection of adult female mosquitoes with biologically relevant concentrations of EVs validated these results in vivo, recapitulating the downregulation of AAEL002590 transcript. This gene was predicted to be involved in the mosquito phenoloxidase (PO) cascade leading to the canonical melanization response and correspondingly, both suppression of this gene using RNAi and parasite EV treatment reduced PO activity in vivo. Our data indicate that parasite-derived EVs interfere with critical immune responses in the vector host, including melanization.

Immunomodulatory role of T helper cells in rheumatoid arthritis : a comprehensive research review

Rheumatoid arthritis (RA) is an autoimmune disease that involves T and B cells and their reciprocal immune interactions with proinflammatory cytokines. T cells, an essential part of the immune system, play an important role in RA. T helper 1 (Th1) cells induce interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α), and interleukin (IL)-2, which are proinflammatory cytokines, leading to cartilage destruction and bone erosion. Th2 cells primarily secrete IL-4, IL-5, and IL-13, which exert anti-inflammatory and anti-osteoclastogenic effects in inflammatory arthritis models. IL-22 secreted by Th17 cells promotes the proliferation of synovial fibroblasts through induction of the chemokine C-C chemokine ligand 2 (CCL2). T follicular helper (Tfh) cells produce IL-21, which is key for B cell stimulation by the C-X-C chemokine receptor 5 (CXCR5) and coexpression with programmed cell death-1 (PD-1) and/or inducible T cell costimulator (ICOS). PD-1 inhibits T cell proliferation and cytokine production. In addition, there are many immunomodulatory agents that promote or inhibit the immunomodulatory role of T helper cells in RA to alleviate disease progression. These findings help to elucidate the aetiology and treatment of RA and point us toward the next steps.

Cite this article: Bone Joint Res 2022;11(7):426–438.

Lead optimisation efforts on a molecular prototype of the immunomodulatory parasitic protein ES-62

The immunomodulatory property of some parasitic helminths is well documented. The glycoprotein ES-62 from the nematode, acanthocheilonema viteae has been found to possess immunomodulatory properties. Two small molecule analogues (SMA’s) of ES-62 (S3 and S5) were found to mimic its immunomodulatory properties in vivo and were active in animal models of allergic, inflammatory and autoimmune diseases. In this work, new efforts were made to further optimise the activities of compound S3 by making small but directed structural changes. A variety of analogues based on the S3 prototype were simulated by making variations at one position and then screened in silico. The best compounds were selected based on predicted physiochemical properties and medicinal chemistry indices and synthesised. Structural elucidation was done via HNMR, LCMS, FTIR and HRESIMS. The predicted properties were evaluated by HPLC method. A total of 11 novel molecules were synthesised and characterised. Significant correlation was obtained between the predicted physicochemical properties and their HPLC retention times (RT) for eight of our novel compounds. This suggests that these compounds may behave in a physiological environment as closely as computationally predicted. This entails, lesser host toxicity while maintaining good or better activities compared to the earlier prototype. They hence provide a good opportunity for development of drugs for immune conditions such as asthma, inflammation and autoimmune diseases.

Cytohesin-2/ARNO: A Novel Bridge Between Cell Migration and Immunoregulation in Synovial Fibroblasts

The guanine nucleotide exchange factor cytohesin-2 (ARNO) is a major activator of the small GTPase ARF6 that has been shown to play an important role(s) in cell adhesion, migration and cytoskeleton reorganization in various cell types and models of disease. Interestingly, dysregulated cell migration, in tandem with hyper-inflammatory responses, is one of the hallmarks associated with activated synovial fibroblasts (SFs) during chronic inflammatory joint diseases, like rheumatoid arthritis. The role of ARNO in this process has previously been unexplored but we hypothesized that the pro-inflammatory milieu of inflamed joints locally induces activation of ARNO-mediated pathways in SFs, promoting an invasive cell phenotype that ultimately leads to bone and cartilage damage. Thus, we used small interference RNA to investigate the impact of ARNO on the pathological migration and inflammatory responses of murine SFs, revealing a fully functional ARNO-ARF6 pathway which can be rapidly activated by IL-1β. Such signalling promotes cell migration and formation of focal adhesions. Unexpectedly, ARNO was also shown to modulate SF-inflammatory responses, dictating their precise cytokine and chemokine expression profile. Our results uncover a novel role for ARNO in SF-dependent inflammation, that potentially links pathogenic migration with initiation of local joint inflammation, offering new approaches for targeting the fibroblast compartment in chronic arthritis and joint disease.

Mini Review: Structure and Function of Nematode Phosphorylcholine-Containing Glycoconjugates

An unusual aspect of the biology of nematodes is the covalent attachment of phosphorylcholine (PC) to carbohydrate in glycoconjugates. Investigation of the structure of these molecules by ever-increasingly sophisticated analytical procedures has revealed that PC is generally in phosphodiester linkage with C6 of N-acetylglucosamine (GlcNAc) in both N-type glycans and glycosphingolipids. Up to five PC groups have been detected in the former, being located on both antenna and core GlcNAc. The PC donor for transfer to carbohydrate appears to be phosphatidylcholine but the enzyme responsible for transfer remains to be identified. Work primarily involving the PC-containing Acanthocheilonema viteae secreted product ES-62, has shown that the PC attached to nematode N-glycans possesses a range of immunomodulatory properties, subverting for example, pro-inflammatory signalling in various immune system cell-types including lymphocytes, mast cells, dendritic cells and macrophages. This has led to the generation of PC-based ES-62 small molecule analogues (SMAs), which mirror the parent molecule in preventing the initiation or progression of disease in mouse models of a number of human conditions associated with aberrant inflammatory responses. These include rheumatoid arthritis, systemic lupus erythematosus and lung and skin allergy such that the SMAs are considered to have widespread therapeutic potential.

Epigenetic drug development for autoimmune and inflammatory diseases

ES-62 is the major secreted protein of the parasitic filarial nematode, Acanthocheilonema viteae. The molecule exists as a large tetramer (MW, ~240kD), which possesses immunomodulatory properties by virtue of multiple phosphorylcholine (PC) moieties attached to N-type glycans. By suppressing inflammatory immune responses, ES-62 can prevent disease development in certain mouse models of allergic and autoimmune conditions, including joint pathology in collagen-induced arthritis (CIA), a model of rheumatoid arthritis (RA). Such protection is associated with functional suppression of "pathogenic" hyper-responsive synovial fibroblasts (SFs), which exhibit an aggressive inflammatory and bone-damaging phenotype induced by their epigenetic rewiring in response to the inflammatory microenvironment of the arthritic joint. Critically, exposure to ES-62 in vivo induces a stably-imprinted CIA-SF phenotype that exhibits functional responses more typical of healthy, Naïve-SFs. Consistent with this, ES-62 "rewiring" of SFs away from the hyper-responsive phenotype is associated with suppression of ERK activation, STAT3 activation and miR-155 upregulation, signals widely associated with SF pathogenesis. Surprisingly however, DNA methylome analysis of Naïve-, CIA- and ES-62-CIA-SF cohorts reveals that rather than simply preventing pathogenic rewiring of SFs, ES-62 induces further changes in DNA methylation under the inflammatory conditions pertaining in the inflamed joint, including targeting genes associated with ciliogenesis, to programme a novel "resolving" CIA-SF phenotype. In addition to introducing a previously unsuspected aspect of ES-62's mechanism of action, such unique behaviour signposts the potential for developing DNA methylation signatures predictive of pathogenesis and its resolution and hence, candidate mechanisms by which novel therapeutic interventions could prevent SFs from perpetuating joint inflammation and destruction in RA. Pertinent to these translational aspects of ES-62-behavior, small molecule analogues (SMAs) based on ES-62's active PC-moieties mimic the rewiring of SFs as well as the protection against joint disease in CIA afforded by the parasitic worm product.

Emerging Role of Eosinophils in Resolution of Arthritis

Eosinophils are a minor component of circulating granulocytes, which are classically viewed as end-stage effector cells in host defense against helminth infection and promoting allergic responses. However, a growing body of evidence has emerged showing that eosinophils are versatile leukocytes acting as an orchestrator in the resolution of inflammation. Rheumatoid arthritis (RA) is the most common chronic inflammatory disease characterized by persistent synovitis that hardly resolves spontaneously. Noteworthy, a specific population of eosinophils, that is, regulatory eosinophils (rEos), was identified in the synovium of RA patients, especially in disease remission. Mechanistically, the rEos in the synovium display a unique pro-resolving signature that is distinct from their counterpart in the lung. Herein, we summarize the latest understanding of eosinophils and their emerging role in promoting the resolution of arthritis. This knowledge is crucial to the design of new approaches to rebalancing immune homeostasis in RA, considering that current therapies are centered on inhibiting pro-inflammatory cytokines and mediators rather than fostering the resolution of inflammation.

Interleukin-35 is a critical regulator of immunity during helminth infections associated with multiple sclerosis

Multiple sclerosis (MS) is currently thought to arise by interactions between genetic susceptibility and environmental factors. Infections in general trigger autoimmune responses causing clinical manifestations of disease. However, as a result of regulatory T (Treg)- and regulatory B (Breg)-cell induction, helminth infections tend to dampen disease activity. IL-35, the newest member of the IL-12 family, is an inhibitory cytokine composed of an EBI3β chain subunit, and an IL-12p35 subunit. The aim of this study was to investigate the role of IL-35 during parasite infections occurring in individuals with MS. Numbers of IL-35-producing Breg cells are higher in CSF from helminth-infected than from uninfected MS subjects, a finding associated with decreased MRI disease activity. Interestingly, stimulation of CD19⁺ B cells with IL-35 promotes conversion of these cells to Breg cells producing both IL-35 and IL-10. Coculture of B cells from helminth-infected MS patients inhibits proliferation of Th1 and Th17 myelin peptide-specific T cells, as well as production of IFN-γ and IL-17. Following activation, CD4⁺ CD25⁺ Treg cells significantly upregulate expression of EBI3 and IL-12p35 mRNA. Furthermore, CD4⁺ CD25^- T cells activated in the presence of IL-35 induce a population of cells with regulatory function, known as iTR35. Finally, B cells from normal individuals cultured in vitro in the presence of the helminth antigen SEA increase expression of the transcription BATF, IRF4 and IRF8, acquiring a pattern similar to that of IL-35 Breg cells. These data highlight the important immunoregulatory effects of IL-35 on both Breg and Treg cells, observed in helminth-infected MS subjects.

Gross ways to live long: Parasitic worms as an anti-inflammaging therapy?

Evolutionary medicine argues that disease can arise because modern conditions do not match those in which we evolved. For example, a decline in exposure to commensal microbes and gastrointestinal helminths in developed countries has been linked to increased prevalence of allergic and autoimmune inflammatory disorders (the hygiene hypothesis). Accordingly, probiotic therapies that restore ‘old friend’ microbes and helminths have been explored as Darwinian treatments for these disorders. A further possibility is that loss of old friend commensals also increases the sterile, aging-associated inflammation known as inflammaging, which contributes to a range of age-related diseases, including cardiovascular disease, dementia, and cancer. Interestingly, Crowe et al., 2020 recently reported that treatment with a secreted glycoprotein from a parasitic nematode can protect against murine aging by induction of anti-inflammatory mechanisms. Here, we explore the hypothesis that restorative helminth therapy would have anti-inflammaging effects. Could worm infections provide broad-spectrum protection against age-related disease?

Proteomic analysis revealed T cell hyporesponsiveness induced by Haemonchus contortus excretory and secretory proteins

Haemonchus contortus has evolved highly integrated and sophisticated mechanisms to promote coexistence with hosts. The excretory-secretory (ES) products generated by this parasite contribute to the regulation of the host immune response to facilitate immune evasion and induce chronicity, but the proteins responsible for this process and the exact cellular mechanisms have yet to be defined. In this study, we identified 114 H. contortus ES proteins (HcESPs) interacting with host T cells and 15 T cell binding receptors via co-immunoprecipitation and shotgun liquid chromatography-tandem mass spectrometry analysis. Based on bioinformatics analysis, we demonstrated that HcESPs could inhibit T cell viability, induce cell apoptosis, suppress T cell proliferation and cause cell cycle arrest. Furthermore, the stimulation of HcESPs exerted critical control effects on T cell cytokine production profiles, predominantly promoting the secretion of interleukin (IL)-10, IL-17A and transforming growth factor-β1 and inhibiting IL-2, IL-4 and interferon-γ production. Collectively, these findings may provide insights into the interaction between ES proteins and key host effector cells, enhancing our understanding of the molecular mechanism underlying parasite immune evasion and providing new clues for novel vaccine development.

The Role of Gamma Delta T Cells in Autoimmune Rheumatic Diseases

Autoimmune rheumatic diseases (ARDs), affecting ~1-1.5% of all humans, are associated with considerable life long morbidity and early mortality. Early studies in the 1990s showed numerical changes of the recently discovered γδ T cells in the peripheral blood and in affected tissues of patients with a variety of ARDs, kindling interest in their role in the immuno-pathogenesis of these chronic inflammatory conditions. Indeed, later studies applied rapid developments in the understanding of γδ T cell biology, including antigens recognized by γδ T cells, their developmental programs, states of activation, and cytokine production profiles, to analyze their contribution to the pathological immune response in these disorders. Here we review the published studies addressing the role of γδ T in the major autoimmune rheumatic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, systemic lupus erythematosus and scleroderma, and animal models thereof. Due to their unique properties spanning adaptive and innate immune functions, the ever deeper understanding of this unique T cell population is shedding new light on the pathogenesis of, while potentially enabling new therapeutic approaches to, these diseases.

Anti-inflammatory and immune-regulatory cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by a failure of spontaneous resolution of inflammation. Although the pro-inflammatory cytokines and mediators that trigger RA have been the focus of intense investigations, the regulatory and anti-inflammatory cytokines responsible for the suppression and resolution of disease in a context-dependent manner have been less well characterized. However, knowledge of the pathways that control the suppression and resolution of inflammation in RA is clinically relevant and conceptually important for understanding the pathophysiology of the disease and for the development of treatments that enable long-term remission. Cytokine-mediated processes such as the activation of T helper 2 cells by IL-4 and IL-13, the resolution of inflammation by IL-9, IL-5-induced eosinophil expansion, IL-33-mediated macrophage polarization, the production of IL-10 by regulatory B cells and IL-27-mediated suppression of lymphoid follicle formation are all involved in governing the regulation and resolution of inflammation in RA. By better understanding these immune-regulatory signalling pathways, new therapeutic strategies for RA can be envisioned that aim to balance and resolve, rather than suppress, inflammation.

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).

Synthetic small molecule analogues of the immunomodulatory Acanthocheilonema viteae product ES-62 promote metabolic homeostasis during obesity in a mouse model

One of the most rapidly increasing human public health problems is obesity, whose sequelae like type-2 diabetes, represent continuously worsening, life-long conditions. Over the last 15 years, data have begun to emerge from human and more frequently, mouse studies, that support the idea that parasitic worm infection can protect against this condition. We have therefore investigated the potential of two synthetic small molecule analogues (SMAs) of the anti-inflammatory Acanthocheilonema viteae product ES-62, to protect against metabolic dysfunction in a C57BL/6 J mouse model of high calorie diet-induced obesity. We found weekly subcutaneous administration of the SMAs in combination (1 μg of each), starting one week before continuous exposure to high calorie diet (HCD), decreased fasting glucose levels and reversed the impaired glucose clearance observed in male mice, when measured at approximately 7 and 13 weeks after exposure to HCD. Fasting glucose levels were also-reduced in male mice fed a HCD for some 38 weeks when given SMA-treatment 13 weeks after the start of HCD, indicating an SMA-therapeutic potential. For the most part, protective effects were not observed in female mice. SMA treatment also conferred protection against each of reduced ileum villus length and liver fibrosis, but more prominently in female mice. Previous studies in mice indicate that protection against metabolic dysfunction is usually associated with polarisation of the immune system towards a type-2/anti-inflammatory direction but our attempts to correlate improved metabolic parameters with such changes were unsuccessful. Further analysis will therefore be required to define mechanism of action. Nevertheless, overall our data clearly show the potential of the drug-like SMAs as a preventative or treatment for metabolic dysregulation associated with obesity.

Helminths products directly modulate T cells that mediate experimental autoimmune encephalomyelitis

Infection with helminths can protect against the development of autoimmune diseases and this has been associated with induction of anti-inflammatory innate immune responses and Tregs. Here, we demonstrate that helminth-derived products can directly target T cells, especially IL-17-secreting γδ T cells that play a key pathogenic role in CNS autoimmune disease.

The parasitic worm product ES-62 normalises the gut microbiota bone marrow axis in inflammatory arthritis

The human immune system has evolved in the context of our colonisation by bacteria, viruses, fungi and parasitic helminths. Reflecting this, the rapid eradication of pathogens appears to have resulted in reduced microbiome diversity and generation of chronically activated immune systems, presaging the recent rise of allergic, autoimmune and metabolic disorders. Certainly, gastrointestinal helminths can protect against gut and lung mucosa inflammatory conditions by modulating the microbiome and suppressing the chronic inflammation associated with dysbiosis. Here, we employ ES-62, an immunomodulator secreted by tissue-dwelling Acanthocheilonema viteae to show that helminth-modulation of the gut microbiome does not require live infection with gastrointestinal-based worms nor is protection restricted to mucosal diseases. Specifically, subcutaneous administration of this defined immunomodulator affords protection against joint disease in collagen-induced arthritis, a mouse model of rheumatoid arthritis, which is associated with normalisation of gut microbiota and prevention of loss of intestinal barrier integrity.

Transcriptome-wide analysis of filarial extract-primed human monocytes reveal changes in LPS-induced PTX3 expression levels

Filarial nematodes modulate immune responses in their host to enable their survival and mediate protective effects against autoimmunity and allergies. In this study, we examined the immunomodulatory capacity of extracts from the human pathogenic filaria Brugia malayi (BmA) on human monocyte responses in a transcriptome-wide manner to identify associated pathways and diseases. As previous transcriptome studies often observed quiescent responses of innate cells to filariae, the potential of BmA to alter LPS driven responses was investigated by analyzing >47.000 transcripts of monocytes from healthy male volunteers stimulated with BmA, Escherichia coli LPS or a sequential stimulation of both. In comparison to ~2200 differentially expressed genes in LPS-only stimulated monocytes, only a limited number of differentially expressed genes were identified upon BmA priming before LPS re-stimulation with only PTX3↓ reaching statistical significance after correcting for multiple testing. Nominal significant differences were reached for metallothioneins↑, MMP9↑, CXCL5/ENA-78↑, CXCL6/GCP-2↑, TNFRSF21↓, and CCL20/MIP3α↓ and were confirmed by qPCR or ELISA. Flow cytometric analysis of activation markers revealed a reduced LPS-induced expression of HLA-DR and CD86 on BmA-primed monocytes as well as a reduced apoptosis of BmA-stimulated monocytes. While our experimental design does not allow a stringent extrapolation of our results to the development of filarial pathology, several genes that were identified in BmA-primed monocytes had previously been associated with filarial pathology, supporting the need for further research.

STAT6 and IL-10 are required for the anti-arthritic effects of Schistosoma mansoni via different mechanisms

To investigate possible roles of T helper type 2 (Th2) cytokines in the anti-arthritic effects of a blood fluke, Schistosoma mansoni (Sm), for mouse collagen-induced arthritis (CIA), wild-type (WT), signal transducer and activator of transcription 6 (STAT6) knock-out (KO) and interleukin (IL)-10 KO mice were infected with Sm. Three weeks after infection, the mice were immunized with bovine type II collagen (IIC). Arthritis severity was monitored by scoring, measurement of paw thickness and the presence of ankylosis. Serum anti-IIC IgG levels, splenic cytokine production and cytokine gene expression in the popliteal lymph nodes (PLNs) were measured and compared among WT and gene-KO mice. Consistent with our previous findings, Sm infection reduced the arthritis severity in WT mice. Splenic production of IL-17A and tumor necrosis factor (TNF)-α was reduced by the infection. In contrast, Sm infection markedly exacerbated CIA in STAT6 KO mice. In the KO mice, IL-17A production was increased by the infection. Conversely, Sm infection did not affect the exacerbated arthritis in IL-10 KO mice, although IL-17A production was reduced by the helminth. Our results suggest that signaling via STAT6 (presumably IL-4 and/or IL-13) and IL-10 is required for the suppression of CIA by Sm infection, but through different mechanisms. STAT6 was essential for helminth-induced reduction of IL-17A, whereas regulation of the basal arthritis severity by IL-10 was needed in order for it to be sufficiently suppressed by the helminth.

Helminth-based therapies for rheumatoid arthritis: A systematic review and meta-analysis

OBJECTIVE

Proteins from parasitic worms have been posed as novel therapies for rheumatoid arthritis (RA) and other auto-inflammatory diseases. However, with so many potential therapeutics, it is important that drug discovery be based on the specific phyla or species which show the most promising effects. Therefore, the aim of this systematic review and meta-analysis was to evaluate the reported effects of helminthic secretory proteins and derivative therapy on RA in an animal model.

METHODS

Medline, Scopus and Web of Science were searched to identify studies evaluating helminthic therapy in the collagen-induced arthritis model of RA. A meta-analysis was undertaken to determine the overall effect of the proteins. Subgroup analyses were also undertaken to investigate individual treatments.

RESULTS

Seven articles were included in the analysis. Overall, helminthic therapy significantly reduced arthritis score (SMD -1.193, 95% CI -1.525, -0.860). Subgroup analyses found a significant reduction in arthritis score following treatment with helminth protein ES-62 (SMD -1.186, 95% CI -1.633, -0.738) and phosphorylcholine-based treatment (SMD -0.997, 95% CI -1.423, -0.571). Subgroup analyses found ES-62 treatment significantly decreased IFN-γ levels (SMD -1.611, 95% CI -2.734, -0.487) and significantly increased levels of IL-10 (SMD 0.946, 95% CI 0.127, 1.765).

CONCLUSIONS

Therapeutics from parasitic worms are a promising avenue for drug discovery, especially with all included studies reporting a significant improvement in arthritis score. Based on pooled data presented in this study, the nematode Acanthocheilonema viteae seems to be of particular interest for therapeutics.

Failure of the Anti-Inflammatory Parasitic Worm Product ES-62 to Provide Protection in Mouse Models of Type I Diabetes, Multiple Sclerosis, and Inflammatory Bowel Disease

Parasitic helminths and their isolated secreted products show promise as novel treatments for allergic and autoimmune conditions in humans. Foremost amongst the secreted products is ES-62, a glycoprotein derived from Acanthocheilonema viteae, a filarial nematode parasite of gerbils, which is anti-inflammatory by virtue of covalently-attached phosphorylcholine (PC) moieties. ES-62 has been found to protect against disease in mouse models of rheumatoid arthritis, systemic lupus erythematosus, and airway hyper-responsiveness. Furthermore, novel PC-based synthetic small molecule analogues (SMAs) of ES-62 have recently been demonstrated to show similar anti-inflammatory properties to the parent molecule. In spite of these successes, we now show that ES-62 and its SMAs are unable to provide protection in mouse models of certain autoimmune conditions where other helminth species or their secreted products can prevent disease development, namely type I diabetes, multiple sclerosis and inflammatory bowel disease. We speculate on the reasons underlying ES-62's failures in these conditions and how the negative data generated may help us to further understand ES-62's mechanism of action.

Immunomodulation by Helminths: Intracellular Pathways and Extracellular Vesicles

Helminth parasites are masters at manipulating host immune responses, using an array of sophisticated mechanisms. One of the major mechanisms enabling helminths to establish chronic infections is the targeting of pattern recognition receptors (PRRs) including toll-like receptors, C-type lectin receptors, and the inflammasome. Given the critical role of these receptors and their intracellular pathways in regulating innate inflammatory responses, and also directing adaptive immunity toward Th1 and Th2 responses, recognition of the pathways triggered and/or modulated by helminths and their products will provide detailed insights about how helminths are able to establish an immunoregulatory environment. However, helminths also target PRRs-independent mechanisms (and most likely other yet unknown mechanisms and pathways) underpinning the battery of different molecules helminths produce. Herein, the current knowledge on intracellular pathways in antigen presenting cells activated by helminth-derived biomolecules is reviewed. Furthermore, we discuss the importance of helminth-derived vesicles as a less-appreciated components released during infection, their role in activating these host intracellular pathways, and their implication in the development of new therapeutic approaches for inflammatory diseases and the possibility of designing a new generation of vaccines.

Protection Against Arthritis by the Parasitic Worm Product ES-62, and Its Drug-Like Small Molecule Analogues, Is Associated With Inhibition of Osteoclastogenesis

The immunomodulatory actions of parasitic helminth excretory-secretory (ES) products that serendipitously protect against development of chronic inflammatory disorders are well established: however, knowledge of the interaction between ES products and the host musculoskeletal system in such diseases is limited. In this study, we have focused on ES-62, a glycoprotein secreted by the rodent filarial nematode Acanthocheilonema viteae that is immunomodulatory by virtue of covalently attached phosphorylcholine (PC) moieties, and also two synthetic drug-like PC-based small molecule analogues (SMAs) that mimic ES-62's immunomodulatory activity. We have previously shown that each of these molecules prevents development of pathology in collagen-induced arthritis (CIA), a model of the musculoskeletal disease rheumatoid arthritis (RA) and reflecting this, we now report that ES-62 and its SMAs, modify bone remodeling by altering bone marrow progenitors and thus impacting on osteoclastogenesis. Consistent with this, we find that these molecules inhibit functional osteoclast differentiation in vitro. Furthermore, this appears to be achieved by induction of anti-oxidant response gene expression, thereby resulting in reduction of the reactive oxygen species production that is necessary for the increased osteoclastogenesis witnessed in musculoskeletal diseases like RA.

Antigen-Specific Tolerization and Targeted Delivery as Therapeutic Strategies for Autoimmune Diseases

The prevalence of autoimmune disorders is increasing steadily and there is no permanent cure available. Immunomodulation through repeated exposure of antigens, known as antigen-specific immune tolerance or antigen-specific immunotherapy (ASI), is a promising approach to treat or prevent autoimmune disorders. Different optimization protocols (immunization routes, delivery systems, and approaches) are being developed to implement ASI against self-proteins. Including appropriate adjuvants, altered peptide ligand, and using multipeptides are approaches that can be used to specifically target autoimmunity. This review explores various ASI application methods, including different routes of antigen-specific sensitization, delivery systems, immunomodulators containing specific antigens, and other targeted approaches that have been successfully demonstrated to have therapeutic effects on autoimmune diseases.

IL-33/ST2 signalling and crosstalk with FcεRI and TLR4 is targeted by the parasitic worm product, ES-62

ES-62 is a secreted parasitic worm-derived immunomodulator that exhibits therapeutic potential in allergy by downregulating aberrant MyD88 signalling to normalise the inflammatory phenotype and mast cell responses. IL-33 plays an important role in driving mast cell responses and promoting type-2 allergic inflammation, particularly with respect to asthma, via MyD88-integrated crosstalk amongst the IL-33 receptor (ST2), TLR4 and FcεRI. We have now investigated whether ES-62 targets this pathogenic network by subverting ST2-signalling, specifically by characterising how the functional outcomes of crosstalk amongst ST2, TLR4 and FcεRI are modulated by the worm product in wild type and ST2-deficient mast cells. This analysis showed that whilst ES-62 inhibits IL-33/ST2 signalling, the precise functional modulation observed varies with receptor usage and/or mast cell phenotype. Thus, whilst ES-62’s harnessing of the capacity of ST2 to sequester MyD88 appears sufficient to mediate its inhibitory effects in peritoneal-derived serosal mast cells, downregulation of MyD88 expression appears to be required to dampen the higher levels of cytokine production typically released by bone marrow-derived mucosal mast cells.

Small Molecule Analogues of the parasitic worm product ES-62 interact with the TIR domain of MyD88 to inhibit pro-inflammatory signalling

ES-62 is a protein secreted by the parasitic worm Acanthocheilonema viteae that is anti-inflammatory by virtue of covalently attached phosphorylcholine. Previously we have reported that drug-like Small Molecule Analogues (SMAs) of its phosphorylcholine moiety can mimic ES-62 in protecting against disease development in certain mouse models of autoimmune and allergic conditions, due to them causing partial degradation of the TLR/IL-1R adaptor MyD88. We have now taken a molecular modelling approach to investigating the mechanism underlying this effect and this predicts that the SMAs interact directly with the MyD88 TIR domain. Further support for this is provided by assay of LPS-induced MyD88/NF-κB-driven secreted alkaline phosphatase (SEAP) reporter activity in commercially-available stably transfected (TLR4-MD2-NF-κB-SEAP) HEK293 cells, as SMA12b-mediated inhibition of such SEAP activity is blocked by its pre-incubation with recombinant MyD88-TIR domain. Direct binding of SMA12b to the TIR domain is also shown to inhibit homo-dimerization of the adaptor, an event that can explain the observed degradation of the adaptor and inhibition of subsequent downstream signalling. Thus, these new data identify initial events by which drug-like ES-62 SMAs, which we also demonstrate are able to inhibit cytokine production by human cells, homeostatically maintain "safe" levels of MyD88 signalling.

The excretory-secretory products of Echinococcus granulosus protoscoleces directly regulate the differentiation of B10, B17 and Th17 cells

Background

Excretory-secretory products (ESPs) released by helminths are well-known to regulate T cell responses in the host. However, their direct influence in the differentiation of naïve T cells, and especially B cells, remains largely unknown. This study investigated the effects of Echinococcus granulosus protoscoleces ESPs (EgPSC-ESPs) on the differentiation of IL-10-producing B cells (B10), IL-17A-producing B cells (B17) and Th17 cells.

Methods

BALB/c mice injected with EgPSC were used to evaluate the in vivo profiles of B10, B17 and Th17 cells. In vitro purified CD19⁺ B and naïve CD4⁺ T cells were cultured in the presence of native, heat-inactivated or periodate-treated EgPSC-ESPs, and the differentiation of these cell subsets were compared.

Results

In contrast to the control group, infected mice showed higher frequencies of B10, B17 and Th17 cells, and higher levels of IL-10 and IL-17A in the sera. Interestingly, B17 cells were first identified to express CD19⁺CD1d^high. In vitro, B cells cultured with native ESPs exhibited a higher percentage of B10 cells but lower percentage of B17 and Th17 cells compared to the PBS group. Moreover, the relative expression of IL-10 and IL-17A mRNA were consistent with the altered frequencies. However, ESPs subjected to heat-inactivation or periodate treatment exhibited an inverse effect on the induction of these cell subsets.

Conclusions

Our findings indicate that ESPs released by EgPSC can directly regulate the differentiation of B10, B17 and Th17 cells, which appear to be heat-labile and carbohydrate-dependent.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2263-9) contains supplementary material, which is available to authorized users.

Can Parasitic Worms Cure the Modern World's Ills?

There has been increasing recognition that the alarming surge in allergy and autoimmunity in the industrialised and developing worlds shadows the rapid eradication of pathogens, such as parasitic helminths. Appreciation of this has fuelled an explosion in research investigating the therapeutic potential of these worms. This review considers the current state-of-play with a particular focus on exciting recent advances in the identification of potential novel targets for immunomodulation that can be exploited therapeutically. Furthermore, we contemplate the prospects for designing worm-derived immunotherapies for an ever-widening range of inflammatory diseases, including, for example, obesity, cardiovascular disease, and ageing as well as neurodevelopmental disorders like autism.

Regulatory B cells in infectious disease (Review)

Regulatory B cells (Bregs) are a subset of B cells, which reportedly exert significant immunomodulatory effects through the production of interleukin (IL)-10, IL-35 and transforming growth factor-β. Over the last decade, studies have indicated that Bregs function in autoimmune and allergic diseases through antigen-specific and non-specific immunoregulatory mechanisms. However, only a limited number of reviews have focused on the role of Bregs during infection, particularly their functions in intracellular infections. The present review discusses the role of Bregs in infectious diseases in animal models and human studies, and provides an overview of the immunoregulatory mechanisms used by Bregs.

Dendritic cells provide a therapeutic target for synthetic small molecule analogues of the parasitic worm product, ES-62

ES-62, a glycoprotein secreted by the parasitic filarial nematode Acanthocheilonema viteae, subverts host immune responses towards anti-inflammatory phenotypes by virtue of covalently attached phosphorylcholine (PC). The PC dictates that ES-62 exhibits protection in murine models of inflammatory disease and hence a library of drug-like PC-based small molecule analogues (SMAs) was synthesised. Four sulfone-containing SMAs termed 11a, 11e, 11i and 12b were found to reduce mouse bone marrow-derived dendritic cell (DC) pathogen-associated molecular pattern (PAMP)-induced pro-inflammatory cytokine production, inhibit NF-κB p65 activation, and suppress LPS-induced up-regulation of CD40 and CD86. Active SMAs also resulted in a DC phenotype that exhibited reduced capacity to prime antigen (Ag)-specific IFN-γ production during co-culture with naïve transgenic TCR DO.11.10 T cells in vitro and reduced their ability, following adoptive transfer, to prime the expansion of Ag-specific T lymphocytes, specifically TH17 cells, in vivo. Consistent with this, mice receiving DCs treated with SMAs exhibited significantly reduced severity of collagen-induced arthritis and this was accompanied by a significant reduction in IL-17+ cells in the draining lymph nodes. Collectively, these studies indicate that drug-like compounds that target DCs can be designed from parasitic worm products and demonstrate the potential for ES-62 SMA-based DC therapy in inflammatory disease.

Parasite excretory-secretory products and their effects on metabolic syndrome

Obesity, one of the main causes of metabolic syndrome (MetS), is an increasingly common health and economic problem worldwide, and one of the major risk factors for developing type 2 diabetes and cardiovascular disease. Chronic, low-grade inflammation is associated with MetS and obesity. A dominant type 2/anti-inflammatory response is required for metabolic homoeostasis within adipose tissue: during obesity, this response is replaced by infiltrating, inflammatory macrophages and T cells. Helminths and certain protozoan parasites are able to manipulate the host immune response towards a TH2 immune phenotype that is beneficial for their survival, and there is emerging data that there is an inverse correlation between the incidence of MetS and helminth infections, suggesting that, as with autoimmune and allergic diseases, helminths may play a protective role against MetS disease. Within this review, we will focus primarily on the excretory-secretory products that the parasites produce to modulate the immune system and discuss their potential use as therapeutics against MetS and its associated pathologies.

From Christian de Duve to Yoshinori Ohsumi: More to autophagy than just dining at home

Christian de Duve first coined the expression “autophagy” during his seminal work on the discovery of lysosomes, which led to him being awarded the Nobel Prize in Physiology or Medicine in 1974. The term was adopted to distinguish degradation of intracellular components from the uptake and degradation of extracellular substances that he called “heterophagy”. Studies until the 1990s were largely observational/morphological-based until in 1993 Yoshinori Oshumi described a genetic screen in yeast undergoing nitrogen deprivation that led to the isolation of autophagy-defective mutants now better known as ATG (AuTophaGy-related) genes. The screen identified mutants that fell into 15 complementation groups implying that at least 15 genes were involved in the regulation of autophagy in yeast undergoing nutrient deprivation, but today, 41 yeast ATG genes have been described and many (though not all) have orthologues in humans. Attempts to identify the genetic basis of autophagy led to an explosion in its research and it's not surprising that in 2016 Yoshinori Oshumi was awarded the Nobel Prize in Physiology or Medicine. Our aim here is not to exhaustively review the ever-expanding autophagy literature (>60 papers per week), but to celebrate Yoshinori Oshumi's Nobel Prize by highlighting just a few aspects that are not normally extensively covered. In an accompanying mini-review we address the role of autophagy in early-diverging eukaryote parasites that like yeast, lack lysosomes and so use a digestive vacuole to degrade autophagosome cargo and also discuss how parasitized host cells react to infection by subverting regulation of autophagy.

Recombinant proteins of helminths with immunoregulatory properties and their possible therapeutic use

The inverse relationship between helminth infections and the development of immune-mediated diseases is a cornerstone of the hygiene hypothesis and studies were carried out to elucidate the mechanisms by which helminth-derived molecules can suppress immunological disorders. These studies have fostered the idea that parasitic worms may be used as a promising therapeutic alternative for prevention and treatment of immune-mediated diseases. We discuss the current approaches for identification of helminth proteins with potential immunoregulatory properties, including the strategies based on high-throughput technologies. We also explore the methodological approaches and expression systems used for production of the recombinant forms of more than 20 helminth immunomodulatory proteins, besides their performances when evaluated as immunotherapeutic molecules to treat different immune-mediated conditions, including asthma and inflammatory bowel diseases. Finally, we discuss the perspectives of using these parasite-derived recombinant molecules as tools for future immunotherapy and immunoprophylaxis of human inflammatory diseases.

Inflammatory arthritis and systemic bone loss are attenuated by gastrointestinal helminth parasites

Infections with different helminth species have been observed to ameliorate a variety of chronic inflammatory diseases. Herein, we show that the natural murine helminth species, Heligmosomoides polygyrus bakeri (Hp) is capable of attenuating disease severity in two different inflammatory arthritis models. Furthermore, we show that excretory-secretory (ES) products from Hp directly suppress osteoclast differentiation in vitro. Taken together, these results demonstrate that helminth infections can dampen autoimmune diseases and highlight a previously unrecognized and important role for ES products, by directly impacting on bone destruction.

The helminth product, ES-62 modulates dendritic cell responses by inducing the selective autophagolysosomal degradation of TLR-transducers, as exemplified by PKCδ

We have previously shown that ES-62, a phosphorylcholine (PC)-containing glycoprotein secreted by the parasitic filarial nematode Acanthocheilonema viteae targets dendritic cell (DC) responses, specifically by suppressing TLR4 signalling to inhibit Th1/Th17-driven inflammation. We have now investigated the molecular mechanisms underpinning such immunomodulation and show here that ES-62-mediated downregulation of protein kinase C-δ (PKC-δ), a TLR4-associated signalling mediator required for full activation of LPS-driven pro-inflammatory responses, is associated with induction of a low level of autophagic flux, as evidenced by upregulation and trafficking of p62 and LC3 and their consequent autophagolysosomal degradation. By contrast, the classical TLR4 ligand LPS, strongly upregulates p62 and LC3 expression but under such canonical TLR4 signalling this upregulation appears to reflect a block in autophagic flux, with these elements predominantly degraded in a proteasomal manner. These data are consistent with autophagic flux acting to homeostatically suppress proinflammatory DC responses and indeed, blocking of PKC-δ degradation by the autophagolysosomal inhibitors, E64d plus pepstatin A, results in abrogation of the ES-62-mediated suppression of LPS-driven release of IL-6, IL-12p70 and TNF-α by DCs. Thus, by harnessing this homeostatic regulatory mechanism, ES-62 can protect against aberrant inflammation, either to promote parasite survival or serendipitously, exhibit therapeutic potential in inflammatory disease.

Mast cells: new therapeutic target in helminth immune modulation

Helminth infection and their secreted antigens have a protective role in many immune-mediated inflammatory disorders such as inflammatory bowel disease, rheumatoid arthritis and multiple sclerosis. However, studies have focused primarily on identifying immune protective mechanisms of helminth infection and their secreted molecules on dendritic cells and macrophages. Given that mast cells have been shown to be implicated in the pathogenesis and progression of many inflammatory disorders, their role should also be examined and considered as cellular target for helminth-based therapies. As there is a dearth of studies examining the interaction of helminth-derived antigens and mast cells, this review will focus on the role of mast cells during helminth infection and examine our current understanding of the involvement of mast cells in TH 1/TH 17-mediated immune disorders. In this context, potential mechanisms by which helminths could target the TH 1/TH 17 promoting properties of mast cells can be identified to unveil novel therapeutic mast cell driven targets in combating these inflammatory disorders.

Human Helminths and Allergic Disease: The Hygiene Hypothesis and Beyond

There is much debate about the interaction between helminths and allergic disease. The "Hygiene Hypothesis," a very popular concept among scientists and the lay public, states that infections, especially during childhood, can protect against allergic diseases. Indeed, helminth infections are known to induce regulatory responses in the host that can help the control of inflammation (including allergic inflammation). However, these infections also induce type-2-associated immune responses including helminth-specific IgE that can cross-react against environmental allergens and mediate IgE-driven effector responses. Thus, it is the delicate balance between the parasites' anti- and pro-allergenic effects that define the helminth/allergy interface.

Downregulation of the Syk Signaling Pathway in Intestinal Dendritic Cells Is Sufficient To Induce Dendritic Cells That Inhibit Colitis

Helminthic infections modulate host immunity and may protect people in less-developed countries from developing immunological diseases. In a murine colitis model, the helminth Heligmosomoides polygyrus bakeri prevents colitis via induction of regulatory dendritic cells (DCs). The mechanism driving the development of these regulatory DCs is unexplored. There is decreased expression of the intracellular signaling pathway spleen tyrosine kinase (Syk) in intestinal DCs from H. polygyrus bakeri-infected mice. To explore the importance of this observation, it was shown that intestinal DCs from DC-specific Syk(-/-) mice were powerful inhibitors of murine colitis, suggesting that loss of Syk was sufficient to convert these cells into their regulatory phenotype. DCs sense gut flora and damaged epithelium via expression of C-type lectin receptors, many of which signal through the Syk signaling pathway. It was observed that gut DCs express mRNA encoding for C-type lectin (CLEC) 7A, CLEC9A, CLEC12A, and CLEC4N. H. polygyrus bakeri infection downmodulated CLEC mRNA expression in these cells. Focusing on CLEC7A, which encodes for the dectin-1 receptor, flow analysis showed that H. polygyrus bakeri decreases dectin-1 expression on the intestinal DC subsets that drive Th1/Th17 development. DCs become unresponsive to the dectin-1 agonist curdlan and fail to phosphorylate Syk after agonist stimulation. Soluble worm products can block CLEC7A and Syk mRNA expression in gut DCs from uninfected mice after a brief in vitro exposure. Thus, downmodulation of Syk expression and phosphorylation in intestinal DCs could be important mechanisms through which helminths induce regulatory DCs that limit colitis.

Diminished IL-17A levels may protect filarial-infected individuals from development of rheumatoid arthritis and systemic lupus erythematosus

Nematode infections have been observed to inversely correlate with autoimmune disorders. Recently, we have shown the absence of filarial infection in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) who live in filarial-endemic areas. The mechanism(s) by which filarial-infected individuals are protected against the development of RA or SLE are unknown. In mice CIA, an experimental model for RA, ES-62, an execratory product of rodent filarial nematode , has been shown to improve arthritis through suppression of the IL-17 pathway. A total of 160 individuals, 40 each of endemic normal, filarial-infected cases, SLE and RA patients, from filarial-endemic areas, were enrolled in the study. Plasma levels of IL17-A, IFN-α and TNF-α were quantified by enzyme-linked immunosorbent assay (ELISA). RA and SLE patients displayed significantly higher plasma IL-17A, IFN-α and TNF-α levels compared to endemic normal and infected individuals. Furthermore, IL-17A levels were significantly low in participants with filarial infection compared to endemic controls ( p < 0.05). Interestingly, plasma IL-17A levels correlated inversely with circulating filarial antigen (CFA) ( p = 0.004, Spearman r = −0.51). Filarial infection was associated with low plasma IL-17A levels, a mechanism by which it possibly protects individuals in filarial-endemic areas from the development of autoimmune disorders like RA and SLE.

Testing small molecule analogues of the Acanthocheilonema viteae immunomodulator ES-62 against clinically relevant allergens

ES-62 is a glycoprotein secreted by the filarial nematode Acanthocheilonema viteae that protects against ovalbumin (OVA)-induced airway hyper-responsiveness in mice by virtue of covalently attached anti-inflammatory phosphorylcholine (PC) residues. We have recently generated a library of small molecule analogues (SMAs) of ES-62 based around its active PC moiety as a starting point in novel drug development for asthma and identified two compounds - termed 11a and 12b - that mirror ES-62's protective effects. In this study, we have moved away from OVA, a model allergen, to test the SMAs against two clinically relevant allergens - house dust mite (HDM) and cockroach allergen (CR) extract. We show that both SMAs offer some protection against development of lung allergic responses to CR, in particular reducing eosinophil infiltration, whereas only SMA 12b is effective in protecting against eosinophil-dependent HDM-induced allergy. These data therefore suggest that helminth molecule-induced protection against model allergens may not necessarily translate to clinically relevant allergens. Nevertheless, in this study, we have managed to demonstrate that it is possible to produce synthetic drug-like molecules based on a parasitic worm product that show therapeutic potential with respect to asthma resulting from known triggers in humans.

Interaction Between Helminths and Toll-Like Receptors: Possibilities and Potentials for Asthma Therapy

Toll-like receptors (TLRs) are essential components of the innate immune system. They play an important role in the pathogenesis of allergic diseases, especially asthma. Since TLRs significantly orchestrate innate and adaptive immune response, their manipulation has widely been considered as a potential approach to control asthma symptoms. It is well established that helminths have immunoregulatory effects on host immune responses, especially innate immunity. They release bioactive molecules such as excretory-secretory (ES) products manipulating TLRs expression and signaling. Thus, given the promising results derived from preclinical studies, harnessing helminth-derived molecules affecting TLRs can be considered as a potential biological therapy for allergic diseases. Prospectively, the data that are available at present suggest that, in the near future, it is possible that helminth antigens will offer new therapeutic strategies and druggable targets for fighting allergic diseases. This review describes the interactions between helminths and TLRs and discusses the potential possibilities for asthma therapy. In this opinion paper, the authors aimed to review the updated literatures on the interplay between helminths, TLRs, and asthma with a view to proposing helminth-based asthma therapy.

Diplomatic Assistance: Can Helminth-Modulated Macrophages Act as Treatment for Inflammatory Disease?

Helminths have evolved numerous pathways to prevent their expulsion or elimination from the host to ensure long-term survival. During infection, they target numerous host cells, including macrophages, to induce an alternatively activated phenotype, which aids elimination of infection, tissue repair, and wound healing. Multiple animal-based studies have demonstrated a significant reduction or complete reversal of disease by helminth infection, treatment with helminth products, or helminth-modulated macrophages in models of allergy, autoimmunity, and sepsis. Experimental studies of macrophage and helminth therapies are being translated into clinical benefits for patients undergoing transplantation and those with multiple sclerosis. Thus, helminths or helminth-modulated macrophages present great possibilities as therapeutic applications for inflammatory diseases in humans. Macrophage-based helminth therapies and the underlying mechanisms of their therapeutic or curative effects represent an under-researched area with the potential to open new avenues of treatment. This review explores the application of helminth-modulated macrophages as a new therapy for inflammatory diseases.

Brugia malayi Antigen (BmA) Inhibits HIV-1 Trans-Infection but Neither BmA nor ES-62 Alter HIV-1 Infectivity of DC Induced CD4+ Th-Cells

One of the hallmarks of HIV-1 disease is the association of heightened CD4+ T-cell activation with HIV-1 replication. Parasitic helminths including filarial nematodes have evolved numerous and complex mechanisms to skew, dampen and evade human immune responses suggesting that HIV-1 infection may be modulated in co-infected individuals. Here we studied the effects of two filarial nematode products, adult worm antigen from Brugia malayi (BmA) and excretory-secretory product 62 (ES-62) from Acanthocheilonema viteae on HIV-1 infection in vitro. Neither BmA nor ES-62 influenced HIV-1 replication in CD4+ enriched T-cells, with either a CCR5- or CXCR4-using virus. BmA, but not ES-62, had the capacity to bind the C-type lectin dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) thereby inhibiting HIV-1 trans-infection of CD4+ enriched T-cells. As for their effect on DCs, neither BmA nor ES-62 could enhance or inhibit DC maturation as determined by CD83, CD86 and HLA-DR expression, or the production of IL-6, IL-10, IL-12 and TNF-α. As expected, due to the unaltered DC phenotype, no differences were found in CD4+ T helper (Th) cell phenotypes induced by DCs treated with either BmA or ES-62. Moreover, the HIV-1 susceptibility of the Th-cell populations induced by BmA or ES-62 exposed DCs was unaffected for both CCR5- and CXCR4-using HIV-1 viruses. In conclusion, although BmA has the potential capacity to interfere with HIV-1 transmission or initial viral dissemination through preventing the virus from interacting with DCs, no differences in the Th-cell polarizing capacity of DCs exposed to BmA or ES-62 were observed. Neither antigenic source demonstrated beneficial or detrimental effects on the HIV-1 susceptibility of CD4+ Th-cells induced by exposed DCs.

From the worm to the pill, the parasitic worm product ES-62 raises new horizons in the treatment of rheumatoid arthritis

Evidence from human studies suggests that parasitic worm infection can protect humans against rheumatoid arthritis (RA) and this idea is strengthened by data generated in model systems. Although therapeutic use of parasitic worms is currently being explored, there are obvious benefits in pursuing drug development through identification and isolation of the 'active ingredients'. ES-62 is a secreted glycoprotein of the filarial nematode Acanthocheilonema viteae, which we have found to protect against the development of collagen-induced arthritis (CIA) in mice. ES-62 activity is dependent on the inflammatory phenotype of the local environment and protection arises via inhibition of Th17- and γδT cell-dependent IL-17 production. At the same time, NK and NK T cell IL-17 production is left intact, and such selectivity suggests that ES-62 might make a particularly attractive therapeutic for RA. However, as a potentially immunogenic protein, ES-62 is unsuitable for development as a drug. Nevertheless, ES-62 activity is dependent on covalently attached phosphorylcholine (PC) residues and we have therefore produced a library of PC-based drug-like ES-62 small-molecule analogues (SMAs) as an alternative therapeutic strategy. Screening this library, we have found an ES-62 SMA that mirrors ES-62 in protecting against CIA and by the same IL-17-dependent mechanism of action.