Parasite worm antigens instruct macrophages to release immunoregulatory extracellular vesicles.

Emerging evidence suggests that immune cells not only communicate with each other through cytokines, chemokines, and cell surface receptors, but also by releasing small membranous structures known as extracellular vesicles (EVs). EVs carry a variety of different molecules that can be taken up by recipient cells. Parasitic worms are well known for their immunomodulatory properties, but whether they can affect immune responses by altering EV-driven communication between host immune cells remains unclear. Here we provide evidence that stimulation of bone marrow-derived macrophages (BMDMs) with soluble products of Trichuris suis (TSPs), leads to the release of EVs with anti-inflammatory properties. Specifically, we found that EVs from TSP-pulsed BMDMs, but not those from unstimulated BMDMs can suppress TNFα and IL-6 release in LPS-stimulated BMDMs and BMDCs. However, no polarization toward M1 or M2 was observed in macrophages exposed to EVs. Moreover, EVs enhanced reactive oxygen species (ROS) production in the exposed BMDMs, which was associated with a deregulated redox homeostasis as revealed by pathway analysis of transcriptomic data. Proteomic analysis identified cytochrome p450 (CYP450) as a potential source of ROS in EVs from TSP-pulsed BMDMs. Finally, pharmacological inhibition of CYP450 activity could suppress ROS production in those BMDMs. In summary, we find that TSPs can modulate immune responses not only via direct interactions but also indirectly by eliciting the release of EVs from BMDMs that exert anti-inflammatory effects on recipient cells.

Identification of antigenic linear peptides in the soil-transmitted helminth and Schistosoma mansoni proteome.

The scientific community identified non stool-based biomarkers as the way forward to support soil-transmitted helminth (STH; Ascaris lumbricoides, Trichuris trichiura and the hookworms Ancylostoma duodenale and Necator americanus) and schistosome (S. mansoni and S. haematobium) deworming programs. This support is needed in making the decision of whether or not to stop preventive chemotherapy intervention efforts and to ultimately transition towards a post-intervention surveillance phase. We applied a two-step micro-array approach to identify antigenic linear epitopes in the STH and S. mansoni proteomes. In a first experiment, we identified antigenic peptides by applying sera from 24 STH and/or S. mansoni infected Ethiopian children on a high-density peptide microarray containing 3.3 million peptides derived from the complete STH and S. mansoni proteomes. A second array experiment with 170,185 peptides that were recognized in the first array was designed to identify non-specific antibody reactivity by applying sera from 24 healthy individuals from Belgium (a non-endemic country). From this array testing cascade, several peptides were identified for STH but none of them appeared to be unique for one species. We therefore concluded that for STH, none of the peptides revealed to be sufficiently sensitive or species specific. For S. mansoni, some promising peptides were identified prompting future investigation. Based on these results, it is unlikely that linear epitopes would be highly useful in detecting species-specific antibody responses to STH in endemic communities. For S. mansoni, one particular peptide of the micro-exon gene 12 (MEG-12) protein deserves further research. In addition, this study emphasizes the need of well-characterized biobanks for biomarker discovery, particularly when the integration of multiple disease programs is envisioned.

Schistosome and intestinal helminth modulation of macrophage immunometabolism.

Macrophages are fundamental to sustain physiological equilibrium and to regulate the pathogenesis of parasitic and metabolic processes. The functional heterogeneity and immune responses of macrophages are shaped by cellular metabolism in response to the host's intrinsic factors, environmental cues and other stimuli during disease. Parasite infections induce a complex cascade of cytokines and metabolites that profoundly remodel the metabolic status of macrophages. In particular, helminths polarize macrophages to an M2 state and induce a metabolic shift towards reliance on oxidative phosphorylation, lipid oxidation and amino acid metabolism. Accumulating data indicate that helminth-induced activation and metabolic reprogramming of macrophages underlie improvement in overall whole-body metabolism, denoted by improved insulin sensitivity, body mass in response to high-fat diet and atherogenic index in mammals. This review aims to highlight the metabolic changes that occur in human and murine-derived macrophages in response to helminth infections and helminth products, with particular interest in schistosomiasis and soil-transmitted helminths.

The deubiquitinase CYLD controls protective immunity against helminth infection by regulation of Treg cell plasticity.

BACKGROUND: Type 2 immunity can be modulated by regulatory T (Treg) cell activity. It has been suggested that the deubiquitinase cylindromatosis (CYLD) plays a role in the development or function of Treg cells, implying that it could be important for normal protective immunity, where type 2 responses are prevalent. OBJECTIVE: We sought to investigate the role of CYLD in Treg cell function and TH2 cell immune responses under steady-state conditions and during helminth infection. METHODS: Foxp3-restricted CYLD conditional knockout (KO) mice were examined in mouse models of allergen-induced airway inflammation and Nippostrongylus brasiliensis infection. We performed multiplex magnetic bead assays, flow cytometry, and quantitative PCR to understand how a lack of CYLD affected cytokine production, homing, and suppression in Treg cells. Target genes regulated by CYLD were identified and validated by microarray analysis, coimmunoprecipitation, short hairpin RNA knockdown, and transfection assays. RESULTS: Treg cell-specific CYLD KO mice showed severe spontaneous pulmonary inflammation with increased migration of Treg cells into the lung. CYLD-deficient Treg cells furthermore produced high levels of IL-4 and failed to suppress allergen-induced lung inflammation. Supporting this, the conditional KO mice displayed enhanced protection against N brasiliensis infection by contributing to type 2 immunity. Treg cell conversion into IL-4-producing cells was due to augmented mitogen-activated protein kinase and nuclear factor κB signaling. Moreover, Scinderin, a member of the actin-binding gelsolin family, was highly upregulated in CYLD-deficient Treg cells, and controlled IL-4 production through forming complexes with mitogen-activated protein kinase kinase/extracellular receptor kinase. Correspondingly, both excessive IL-4 production in vivo and the protective role of CYLD-deficient Treg cells against N brasiliensis were reversed by Scinderin ablation. CONCLUSIONS: Our findings indicate that CYLD controls type 2 immune responses by regulating Treg cell conversion into TH2 cell-like effector cells, which potentiates parasite resistance.

Eosinophils and White Fat: Protection from Worms and Inflammaging.

Proinflammatory alterations of white adipose tissue (WAT) with increasing age play an important role in mammalian aging. WAT produced eotaxin-1 (CCL11-C-C motif chemokine ligand 11) and monocyte chemoattractant protein 1 (MCP-1) (CCL2) are elevated in old mammals. Obese and old adipose tissues produce excessive proinflammatory cytokines such as interleukin (IL)-6, CCL2, and IL-1-beta that contribute to inflammaging. WAT-based inflammaging involves an altered homeostatic equilibrium between proinflammatory cells such as activated type 1 macrophages, B cells (high IgJ) and T cells, and anti-inflammatory eosinophils and Tregs. Specifically, young and lean individuals exhibit a high eosinophil-to-macrophage ratio with an enrichment of alternative activated tissue macrophages that is reduced in the WAT of aging mice. Eosinophils from young animals adoptively transferred to old mice, home to WAT and reverse many of the immunoinflammatory signatures associated with aging. Whether eosinophil-based therapies for inflammaging could be created remains an open question.

Frontiers in Molecular Evolutionary Medicine.

This paper surveys some of the important insights that molecular evolution has contributed to evolutionary medicine; they include phage therapy, cancer biology, helminth manipulation of the host immune system, quality control of gametes, and pathogen outbreaks. Molecular evolution has helped to revolutionize our understanding of cancer, of autoimmune disease, and of the origin, spread, and pathogenesis of emerging diseases, where it has suggested new therapies, illuminated mechanisms, and revealed historical processes: all have practical therapeutic implications. While much has been accomplished, much remains to be done.

TFF3 interacts with LINGO2 to regulate EGFR activation for protection against colitis and gastrointestinal helminths.

Intestinal epithelial cells (IEC) have important functions in nutrient absorption, barrier integrity, regeneration, pathogen-sensing, and mucus secretion. Goblet cells are a specialized cell type of IEC that secrete Trefoil factor 3 (TFF3) to regulate mucus viscosity and wound healing, but whether TFF3-responsiveness requires a receptor is unclear. Here, we show that leucine rich repeat receptor and nogo-interacting protein 2 (LINGO2) is essential for TFF3-mediated functions. LINGO2 immunoprecipitates with TFF3, co-localizes with TFF3 on the cell membrane of IEC, and allows TFF3 to block apoptosis. We further show that TFF3-LINGO2 interactions disrupt EGFR-LINGO2 complexes resulting in enhanced EGFR signaling. Excessive basal EGFR activation in Lingo2 deficient mice increases disease severity during colitis and augments immunity against helminth infection. Conversely, TFF3 deficiency reduces helminth immunity. Thus, TFF3-LINGO2 interactions de-repress inhibitory LINGO2-EGFR complexes, allowing TFF3 to drive wound healing and immunity.

Eosinophils and Macrophages within the Th2-Induced Granuloma: Balancing Killing and Healing in a Tight Space.

Granuloma formation is a key host immune response generated to confine invading pathogens and limit extensive host damage. It consists of an accumulation of host immune cells around a pathogen. This host response has been extensively studied in the context of inflammatory diseases. However, there is much less known about Th2-type granulomas generated in response to parasitic worms. Based on in vitro data, innate immune cells within the granuloma are thought to immobilize and kill parasites but also act to repair damaged tissue. Understanding this dual function is key. The two billion people and many livestock/wild animals infected with helminths demonstrate that granulomas are not effective at clearing infection. However, the lack of high mortality highlights their importance in ensuring that parasite migration/tissue damage is restricted and wound healing is effective. In this review, we define two key cellular players (macrophages and eosinophils) and their associated molecular players involved in Th2 granuloma function. To date, the underlying mechanisms remain poorly understood, which is in part due to a lack of conclusive studies. Most have been performed in vitro rather than in vivo, using cells that have not been obtained from granulomas. Experiments using genetically modified mouse strains and/or antibody/chemical-mediated cell depletion have also generated conflicting results depending on the model. We discuss the caveats of previous studies and the new tools available that will help fill the gaps in our knowledge and allow a better understanding of the balance between immune killing and healing.

Helminth Defense Molecules as Design Templates for Membrane Active Antibiotics.

A design template for membrane active antibiotics against microbial and tumor cells is described. The template is an amino acid sequence that combines the properties of helminth defense molecules, which are not cytolytic, with the properties of host-defense peptides, which disrupt microbial membranes. Like helminth defense molecules, the template folds into an amphipathic helix in both mammalian host and microbial phospholipid membranes. Unlike these molecules, the template exhibits antimicrobial and anticancer properties that are comparable to those of antimicrobial and anticancer antibiotics. The selective antibiotic activity of the template builds upon a functional synergy between three distinctive faces of the helix, which is in contrast to two faces of membrane-disrupting amphipathic structures. This synergy enables the template to adapt pore formation mechanisms according to the nature of the target membrane, inducing the lysis of microbial and tumor cells.

Notch Signaling Orchestrates Helminth-Induced Type 2 Inflammation.

Infection with helminth parasites poses a significant challenge to the mammalian immune system. The type 2 immune response to helminth infection is critical in limiting worm-induced tissue damage and expelling parasites. Conversely, aberrant type 2 inflammation can cause debilitating allergic disease. Recent studies have revealed that key type 2 inflammation-associated immune and epithelial cell types respond to Notch signaling, broadly regulating gene expression programs in cell development and function. Here, we discuss new advances demonstrating that Notch is active in the development, recruitment, localization, and cytokine production of immune and epithelial effector cells during type 2 inflammation. Understanding how Notch signaling controls type 2 inflammatory processes could inform the development of Notch pathway modulators to treat helminth infections and allergies.

Group 2 Innate Lymphoid Cells (ILC2): Type 2 Immunity and Helminth Immunity.

Group 2 innate lymphoid cells (ILC2) have emerged as a major component of type 2 inflammation in mice and humans. ILC2 secrete large amounts of interleukins 5 and 13, which are largely responsible for host protective immunity against helminth parasites because these cytokines induce profound changes in host physiology that include: goblet cell metaplasia, mucus accumulation, smooth muscle hypercontractility, eosinophil and mast cell recruitment, and alternative macrophage activation (M2). This review covers the initial recognition of ILC2 as a distinct cell lineage, the key studies that established their biological importance, particularly in helminth infection, and the new directions that are likely to be the focus of emerging work that further explores this unique cell population in the context of health and disease.

B-1 cell response in immunity against parasites.

The peritoneal cavity has a microenvironment capable of promoting proliferation, differentiation, and activation of the resident cells and recruitment of blood cells through the capillary network involved in the peritoneum. Among the cells found in the peritoneal cavity, B-1 cells are a particular cell type that contains features that are not very well defined. These cells differ from conventional B lymphocytes (B-2) by phenotypic, functional, and molecular characteristics. B-1 cells can produce natural antibodies, migrate to the inflammatory focus, and have the ability to phagocytose pathogens. However, the role of B-1 cells in immunity against parasites is still not completely understood. Several experimental models have demonstrated that B-1 cells can affect the susceptibility or resistance to parasite infections depending on the model and species. Here, we review the literature to provide information on the peculiarities of B-1 lymphocytes as well as their interaction with parasites.

Therapeutic Potential of Helminths and Helminth-Derived Antigens for Resolution of Inflammation in Inflammatory Bowel Disease.

Inflammation plays a pivotal role in the pathogenesis of inflammatory bowel disease (IBD), and treatment of IBD mainly targets on inhibition of pro-inflammatory mediators. Helminth-based therapy is a novel strategy for resolution of inflammation in IBD, because helminths have great immunomodulatory properties. Helminth-based therapy may be efficacious as a vaccine for patients with IBD. This article is a highlight on the therapeutic potential of helminths in IBD.

Helminths protect against type 1 diabetes: effects and mechanisms.

Type 1 diabetes (T1D) is an autoimmune disease in which cells of the immune system destroy pancreatic ß cells, which secrete insulin. The high prevalence of T1D in developed societies may be explained by environmental changes, including lower exposure to helminths. Indeed, infection by helminths such as Schistosoma, Filaria, and Heligmosomoides polygyrus and their by-products has been reported to ameliorate or prevent the development of T1D in human and animal models. Helminths can trigger distinct immune regulatory pathways, often involving adaptive immune cells that include T helper 2 (Th2) cells and regulatory T cells (Tregs) and innate immune cells that include dendritic cells, macrophages, and invariant natural killer T cells, which may act synergistically to induce Tregs in a Toll-like receptor-dependent manner. Cytokines such as interleukin (IL)-4, IL-10, and transforming growth factor (TGF)-ß also play an important role in protection from T1D. Herein, we provide a comprehensive review of the effects and mechanisms underlying protection against T1D by helminths.

Modulation of Host Immunity by Helminths: The Expanding Repertoire of Parasite Effector Molecules.

Helminths are extraordinarily successful parasites due to their ability to modulate the host immune response. They have evolved a spectrum of immunomodulatory molecules that are now beginning to be defined, heralding a molecular revolution in parasite immunology. These discoveries have the potential both to transform our understanding of parasite adaptation to the host and to develop possible therapies for immune-mediated disease. In this review we will summarize the current state of the art in parasite immunomodulation and discuss perspectives on future areas for research and discovery.

First Responders: Innate Immunity to Helminths.

Helminth infections represent a significant public health concern resulting in devastating morbidity and economic consequences across the globe. Helminths migrate through mucosal sites causing tissue damage and the induction of type 2 immune responses. Antihelminth protection relies on the mobilization and activation of multiple immune cells, including type 2 innate lymphocytes (ILC2s), basophils, mast cells, macrophages, and hematopoietic stem/progenitor cells. Further, epithelial cells and neurons have been recognized as important regulators of type 2 immunity. Collectively, these pathways stimulate host-protective responses necessary for worm expulsion and the healing of affected tissues. In this review we focus on the innate immune pathways that regulate immunity to helminth parasites and describe how better understanding of these pathways may lead to the development of new therapeutic strategies.

Parasites as negative regulators of cancer.

Several environmental factors (chemical, physical, and biological) can cause the initiation, promotion, and progression of cancer. Regarding the biological factors, several studies have found that infections caused by some bacteria, viruses and protozoan, and helminth parasites are related to carcinogenesis. However, in recent years a different approach has been implemented on the antitumor impact of parasitic diseases caused by some protozoan and helminths, mainly because such infections may affect several hallmarks of cancer, but the involved mechanisms still remain unknown. The beneficial effects reported for some parasitic diseases on tumorigenesis range from the induction of apoptosis, activation of the immune response, avoiding metastasis and angiogenesis, inhibition of proliferative signals, to the regulation of inflammatory responses that promote cancer. In this work, we reviewed the available information regarding how parasitic infections may modulate cancer progression. Despite the fact that specific mechanisms of action on tumors are not yet totally clear, we consider that detailed studies of the antitumor action of these organisms and their products could lead to the discovery and use of new molecules from these biological agents that may work as adjuvant therapy in the treatment of various types of cancer.

Characterizing Activation, Proliferation, and Ontogeny of Murine Macrophages in Parasitic Helminth Infections.

Helminth parasites infect approximately 1/3 of the human population. They induce a characteristic immune response whose main focus seems to be to contain the worm parasites and avoid excessive damage to the host. Macrophages are a central player in this response and research using helminth infection models has highlighted the heterogeneity of macrophage responses including distinct recruitment mechanisms, subset-specific activation profiles, and functional diversity. Thus, helminth infection models offer the excellent opportunity to analyze a unique part of the macrophage activation spectrum as well as dissect the functional contributions of macrophages to a wide variety of biologically relevant conditions like wound healing, fibrosis, and immunoregulation.As an example for the analysis of macrophages associated with helminth infection this chapter describes the isolation and magnetic enrichment of pleural macrophages from mice infected with the natural rodent parasite Litomosoides sigmodontis. In addition, it includes a detailed description of how to determine the ontogeny and proliferation status of macrophage populations in helminth infections. Although the focus of this chapter is on helminth infection-derived macrophages, the described methods can easily be adapted to other disease models.

The tropics, helminth infections and hygiene hypotheses.

The Tropics is very appropriate to test the hypotheses raised to explain the increasing trends of allergy and other inflammatory diseases worldwide. The absence of parasite infection as a possible cause of the increase of allergic diseases was proposed by J. Gerrard a long time ago; however, the idea that helminth infections, which induce a strong Th2 could reduce allergy symptoms seems counterintuitive; but the fact is that they have a dual effect: they increase the Th2 responses but also exert immunosuppression and both effects influence the symptoms of allergy. Basic experimentation has provided valuable information about the mechanisms of allergic inflammation and more recently, about its control by helminth induced immunomodulation, discovering helminth molecules with anti-inflammatory properties that are meant to replace the live helminth therapeutic approaches. The immunosuppressive power of helminths makes them excellent candidates to be considered in the hygiene hypotheses. Future comprehensive studies evaluating simultaneously the role of microbial infections, helminth infections, microbiota, pollution and biodiversity will help to elucidate the causes of the increasing trends of allergic disorders. Doing this in the tropics, where all these variables are still present could be difficult but no doubt that will be more informative.

Novel Therapeutics for Multiple Sclerosis Designed by Parasitic Worms.

The evolutionary response to endemic infections with parasitic worms (helminth) was the development of a distinct regulatory immune profile arising from the need to encapsulate the helminths while simultaneously repairing tissue damage. According to the old friend's hypothesis, the diminished exposure to these parasites in the developed world has resulted in a dysregulated immune response that contributes to the increased incidence of immune mediated diseases such as Multiple Sclerosis (MS). Indeed, the global distribution of MS shows an inverse correlation to the prevalence of helminth infection. On this basis, the possibility of treating MS with helminth infection has been explored in animal models and phase 1 and 2 human clinical trials. However, the possibility also exists that the individual immune modulatory molecules secreted by helminth parasites may offer a more defined therapeutic strategy.