The schistosome glutathione S-transferase P28GST, a unique helminth protein, prevents intestinal inflammation in experimental colitis through a Th2-type response with mucosal eosinophils

Therapeutic and vaccinomic potential of moonlighting proteins for the discovery and design of drugs and vaccines against schistosomiasis

Despite significant and coordinated efforts to combat schistosomiasis, such as providing clean water, sanitation, hygiene, and snail control, these strategies still fall short, as regions previously thought to be disease-free have shown active schistosomiasis transmission. Therefore, it is necessary to implement integrated control methods, emphasizing vaccine development for sustainable control of schistosomiasis. Vaccination has significantly contributed to global healthcare and has been the most economically friendly method for avoiding pathogenic infections. Over the years, different vaccine candidates for schistosomiasis have been investigated with varying degrees of success in clinical trials with many not proceeding past the early clinical phase. Recently, proteins have been mentioned as targets for drug discovery and vaccine development, especially those with multiple functions in schistosomes. Moonlighting proteins are a class of proteins that can perform several functions besides their known functions. This multifunctional property is believed to have been expressed through evolution, where the polypeptide chain gained the ability to perform other tasks without undergoing any structural changes. Since proteins have gained more traction as drug targets, multifunctional proteins have thus become attractive for discovering and developing novel drugs since the drug can target more than one function. Moonlighting proteins are promising drug and vaccine candidates for diseases such as schistosomiasis, since they aid in disease promotion in the human host. This manuscript elucidates vital moonlighting proteins used by schistosomes to drive their life cycle and to ensure their survival in the human host, which can be used to develop anti-schistosomal therapeutics and vaccinomics.

Biochemical characterization and gene structure analysis of the 24-kDa glutathione transferase sigma from Taenia solium

Taenia solium can cause human taeniasis and/or cysticercosis. The latter can in some instances cause human neurocysticercosis which is considered a priority in disease-control strategies and the prevention of mental health problems. Glutathione transferases are crucial for the establishment and long-term survival of T. solium; therefore, we structurally analyzed the 24-kDa glutathione transferase gene (Ts24gst) of T. solium and biochemically characterized its product. The gene promoter showed potential binding sites for transcription factors and xenobiotic regulatory elements. The gene consists of a transcription start site, four exons split by three introns, and a polyadenylation site. The gene architecture is conserved in cestodes. Recombinant Ts24GST (rTs24GST) was active and dimeric. Anti-rTs24GST serum showed slight cross-reactivity with human sigma-class GST. A 3D model of Ts24GST enabled identification of putative residues involved in interactions of the G-site with GSH and of the H-site with CDNB and prostaglandin D2. Furthermore, rTs24GST showed optimal activity at 45 °C and pH 9, as well as high structural stability in a wide range of temperatures and pHs. These results contribute to the better understanding of this parasite and the efforts directed to fight taeniasis/cysticercosis.

Helminth-derived proteins as immune system regulators: a systematic review of their promise in alleviating colitis

Helminth-derived proteins have immunomodulatory properties, influencing the host's immune response as an adaptive strategy for helminth survival. Helminth-derived proteins modulate the immune response by inducing anti-inflammatory cytokines, promoting regulatory T-cell development, and ultimately favouring a Th2-biased immune response. This systematic review focused on helminth-derived proteins and explored their impact on reducing inflammatory responses in mouse models of colitis. A systematic search across Medline, EMBASE, Web of Science, and Cochrane Library identified fourteen relevant studies. These studies reported immunomodulatory changes, including increased production of anti-inflammatory cells and cytokines. In mouse models of colitis treated with on helminth-derived proteins, significant improvements in pathological parameters such as body weight, colon length, and microscopic inflammatory scores were observed compared to control groups. Moreover, helminth-derived proteins can enhance the function of Tregs and alleviate the severity of inflammatory conditions. The findings underscore the pivotal role of helminth-derived proteins in immunomodulation, specifically in the axis of cytokine secretion and immune cell polarization. The findings offer new opportunities for treating chronic inflammatory conditions such Crohn's disease.

Manganese- and zinc-coordinated interaction of Schistosoma japonicum glutathione S-transferase with neurotransmitter transporters GlyT1 and GAT3 in vitro

Glutathione S-transferases (GSTs) are a family of multifunctional isoenzymes involved in the neutralization of toxic compounds, drug resistance and several other cellular functions. The glutathione S-transferase enzyme of Schistosoma japonicum (SjGST-26) plays a role in human schistosomiasis and is also a frequently used fusion partner in mammalian and bacterial expression and pull-down systems. GSTs seem not to be naturally associated with metal ions. Exceptionally, in vitro, metal binding sites have been previously described in some schistosome GSTs; however, their possible physiological role is unclear. Molecules of several neurotransmitter transporters also contain a regulatory zinc binding site, which affects their transport cycle. Here we show that among several metals, manganese and zinc are able to induce a specific protein interaction of SjGST-26 with the glycine transporter GlyT1 and the GABA transporter GAT3 in vitro. The results suggest that metal-binding sites on SjGST-26 and neurotransmitter transporters might function in metal-coordinated interactions with other metalloproteins. Our results additionally indicate that the presence of metal ions in SjGST-26-based GST protein pull-down assays may lead to a false-positive interaction if the potential interacting target is the metalloprotein.

Vaccines for immune tolerance against autoimmune disease

The high prevalence and rising incidence of autoimmune diseases have become a prominent public health issue. Autoimmune disorders result from the immune system erroneously attacking the body's own healthy cells and tissues, causing persistent inflammation, tissue injury, and impaired organ function. Existing treatments primarily rely on broad immunosuppression, leaving patients vulnerable to infections and necessitating lifelong treatments. To address these unmet needs, an emerging frontier of vaccine development aims to restore immune equilibrium by inducing immune tolerance to autoantigens, offering a potential avenue for a cure rather than mere symptom management. We discuss this burgeoning field of vaccine development against inflammation and autoimmune diseases, with a focus on common autoimmune disorders, including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, inflammatory bowel disease, and systemic lupus erythematosus. Vaccine-based strategies provide a new pathway for the future of autoimmune disease therapeutics, heralding a new era in the battle against inflammation and autoimmunity.

Sja-Let-7 Attenuates Carbon Tetrachloride-Induced Liver Fibrosis in a Mouse Model via Col1α2

Liver fibrosis (LF) is a chronic progressive disease with no definitive treatment. The aim of this study was to assess helminth-derived molecules as potential therapeutic targets to prevent or reverse LF. A mouse model of carbon tetrachloride (CCL4)-induced LF was established and sja-let-7 was overexpressed by treatment with a miRNA agomir once per week. After four weeks, serum biochemistry, hepatic hydroxyproline content measurements, liver histology, mRNA expression profiling of fibrotic markers, the dual-luciferase reporter assay, and fluorescence in situ hybridization (FISH) were performed. Administration of the sja-let-7 agomir markedly ameliorated hepatosplenomegaly and reduced the liver hydroxyproline content. Liver histological analysis showed significant reductions in collagen deposition in the sja-let-7 agomir-treated mice. Additionally, the mRNA levels of both pro-fibrotic markers and pro-inflammatory cytokines were diminished after treatment. Furthermore, the dual-luciferase reporter assay and FISH identified the α2 chain of collagen type 1 (Col1α2) as the direct target of sja-let-7. Accordingly, the progression of LF was attenuated by targeting Col1α2 and the TGF-β/Smad signaling pathway.

Helminth-derived biomacromolecules as therapeutic agents for treating inflammatory and infectious diseases: What lessons do we get from recent findings?

Despite the tremendous progress in healthcare sectors, a number of life-threatening infectious, inflammatory, and autoimmune diseases are continuously challenging mankind throughout the globe. In this context, recent successes in utilizing helminth parasite-derived bioactive macromolecules viz. glycoproteins, enzymes, polysaccharides, lipids/lipoproteins, nucleic acids/nucleotides, and small organic molecules for treating various disorders primarily resulted from inflammation. Among the several parasites that infect humans, helminths (cestodes, nematodes, and trematodes) are known as efficient immune manipulators owing to their explicit ability to modulate and modify the innate and adaptive immune responses of humans. These molecules selectively bind to immune receptors on innate and adaptive immune cells and trigger multiple signaling pathways to elicit anti-inflammatory cytokines, expansion of alternatively activated macrophages, T-helper 2, and immunoregulatory T regulatory cell types to induce an anti-inflammatory milieu. Reduction of pro-inflammatory responses and repair of tissue damage by these anti-inflammatory mediators have been exploited for treating a number of autoimmune, allergic, and metabolic diseases. Herein, the potential and promises of different helminths/helminth-derived products as therapeutic agents in ameliorating immunopathology of different human diseases and their mechanistic insights of function at cell and molecular level alongside the molecular signaling cross-talks have been reviewed by incorporating up-to-date findings achieved in the field.

Eosinophil-derived IL-4 is necessary to establish the inflammatory structure in innate inflammation

Pathogen-induced inflammation comprises pro- and anti-inflammatory processes, which ensure pathogen removal and containment of the proinflammatory activities. Here, we aimed to identify the development of inflammatory microenvironments and their maintenance throughout the course of a toll-like receptor 2-mediated paw inflammation. Within 24 h after pathogen-injection, the immune cells were organized in three zones, which comprised a pathogen-containing "core-region", a bordering proinflammatory (PI)-region and an outer anti-inflammatory (AI)-region. Eosinophils were present in all three inflammatory regions and adapted their cytokine profile according to their localization. Eosinophil depletion reduced IL-4 levels and increased edema formation as well as mechanical and thermal hypersensitivities during resolution of inflammation. Also, in the absence of eosinophils PI- and AI-regions could not be determined anymore, neutrophil numbers increased, and efferocytosis as well as M2-macrophage polarization were reduced. IL-4 administration restored in eosinophil-depleted mice PI- and AI-regions, normalized neutrophil numbers, efferocytosis, M2-macrophage polarization as well as resolution of zymosan-induced hypersensitivity. In conclusion, IL-4-expressing eosinophils support the resolution of inflammation by enabling the development of an anti-inflammatory framework, which encloses proinflammatory regions.

Protection from T cell-dependent colitis by the helminth-derived immunomodulatory mimic of transforming growth factor-β, Hp-TGM

In animal models of inflammatory colitis, pathology can be ameliorated by several intestinal helminth parasites, including the mouse nematode Heligmosomoides polygyrus. To identify parasite products that may exert anti-inflammatory effects in vivo, we tested H. polygyrus excretory-secretory (HES) products, as well as a recombinantly expressed parasite protein, transforming growth factor mimic (TGM), that functionally mimics the mammalian immunomodulatory cytokine TGF-β. HES and TGM showed a degree of protection in dextran sodium sulphate-induced colitis, with a reduction in inflammatory cytokines, but did not fully block the development of pathology. HES also showed little benefit in a similar acute trinitrobenzene sulphonic acid-induced model. However, in a T cell transfer-mediated model with recombination activation gene (RAG)-deficient mice, HES-reduced disease scores if administered throughout the first 2 or 4 weeks following transfer but was less effective if treatment was delayed until 14 days after T cell transfer. Recombinant TGM similarly dampened colitis in RAG-deficient recipients of effector T cells, and was effective even if introduced only once symptoms had begun to be manifest. These results are a promising indication that TGM may replicate, and even surpass, the modulatory properties of native parasite HES.

Treatment with Extracellular Vesicles from Giardia lamblia Alleviates Dextran Sulfate Sodium-Induced Colitis in C57BL/6 Mice

Inflammatory bowel disease (IBD) is a chronic and recurrent illness of the gastrointestinal tract. Treatment of IBD traditionally involves the use of aminosalicylic acid and steroids, while these drugs has been associated with untoward effects and refractoriness. The absence of effective treatment regimen against IBD has led to the exploration of new targets. Parasites are promising as an alternative therapy for IBD. Recent studies have highlighted the use of parasite-derived substances, such as excretory secretory products, extracellular vesicles (EVs), and exosomes, for the treatment of IBD. In this report, we examined whether EVs secreted by Giardia lamblia could prevent colitis in a mouse model. G. lamblia EVs (GlEVs) were prepared from in vitro cultures of Giardia trophozoites. Clinical signs, microscopic colon tissue inflammation, and cytokine expression levels were detected to assess the effect of GlEV treatment on dextran sulfate sodium (DSS)-induced experimental murine colitis. The administration of GlEVs prior to DSS challenge reduced the expression levels of pro-inflammatory cytokines, including tumor necrosis factor alpha, interleukin 1 beta, and interferon gamma. Our results indicate that GlEV can exert preventive effects and possess therapeutic properties against DSS-induced colitis.

Preexisting Trichinella spiralis infection attenuates the severity of Pseudomonas aeruginosa-induced pneumonia

Background

A range of helminth species involve the migration of developing larvae through the lung and establish chronic infections in the host that include potent immune regulatory effects. Trichinella spiralis is one of the most successful parasitic symbiotes. After released by intestinal female adult worms, newborn larvae of T. spiralis travel through the circulatory system to the lung and finally reach skeletal muscle cells. As unique inflammation modulator of intracellular parasitism, T. spiralis shows improved responses to autoimmune disease and viral pulmonary inflammation by exerting immunomodulatory effects on innate and adaptive immune cells.

Methodology/Principal findings

C57BL/6 mice were divided into four groups: uninfected; helminth- T. spiralis infected; P. aeruginosa infected; and co-infected. Mice infected with T. spiralis were incubated for 6 weeks, followed by P. aeruginosa intranasal inoculation. Bronchial alveolar lavage fluid, blood and lung samples were analyzed. We found that T. spiralis induced Th2 response in the mouse lung tissue, increased lung CD4⁺ T cells, GATA3, IL-4, IL-5 and IL-13 expression. Pre-existing T. spiralis infection decreased lung neutrophil recruitment, inflammatory mediator IL-1β and IL-6 expression and chemokine CXCL1 and CXCL2 release during P. aeruginosa- pneumonia. Furthermore, T. spiralis co-infected mice exhibited significantly more eosinophils at 6 hours following P. aeruginosa infection, ameliorated pulmonary inflammation and improved survival in P. aeruginosa pneumonia.

Conclusions

These findings indicate that a prior infection with T. spiralis ameliorates experimental pulmonary inflammation and improves survival in P. aeruginosa pneumonia through a Th2-type response with eosinophils.

Helminth infections elicit type 2 immunity, which influences host immune responses to additional threats, such as allergens, metabolic disease and other pathogens. Pseudomonas aeruginosa is one of the most common gram-negative pathogens causing pneumonia in immunocompromised patients. The mortality rate of ventilator associated pneumonia caused by P. aeruginosa is higher than that due to other pathogens. Trichinella spiralis is a zoonotic nematode of intracellular parasitism that infects a wide range of vertebrate hosts, including humans. There is a lung migratory phase in the life cycle of T. spiralis. In this study, we found that T. spiralis induced Th2 response in the mouse lung tissue. T. spiralis co-infected mice exhibited significantly more eosinophils and less neutrophils at 6 hours following P. aeruginosa infection, ameliorated pulmonary inflammation and improved survival in P. aeruginosa pneumonia. These findings suggest a pre-existing chronic helminth with a lung migration phase infection promotes the survival of bacterial airway co-infected host.

SINAPs: A Software Tool for Analysis and Visualization of Interaction Networks of Molecular Dynamics Simulations

As long as the structural study of molecular mechanisms requires multiple molecular dynamics reflecting contrasted bioactive states, the subsequent analysis of molecular interaction networks remains a bottleneck to be fairly treated and requires a user-friendly 3D view of key interactions. Structural Interaction Network Analysis Protocols (SINAPs) is a proprietary python tool developed to (i) quickly solve key interactions able to distinguish two protein states, either from two sets of molecular dynamics simulations or from two crystallographic structures, and (ii) render a user-friendly 3D view of these key interactions through a plugin of UCSF Chimera, one of the most popular open-source viewing software for biomolecular systems. Through two case studies, glucose transporter-1 (GLUT-1) and A2A adenosine receptor (A2AR), SINAPs easily pinpointed key interactions observed experimentally and relevant for their bioactivities. This very effective tool was thus applied to identify the amino acids involved in the molecular enzymatic mechanisms ruling the activation of an immunomodulator drug candidate, P28 glutathione-S-transferase (P28GST). SINAPs is freely available at https://github.com/ParImmune/SINAPs.

Peptide-based delivery of therapeutics in cancer treatment

Current delivery strategies for cancer therapeutics commonly cause significant systemic side effects due to required high doses of therapeutic, inefficient cellular uptake of drug, and poor cell selectivity. Peptide-based delivery systems have shown the ability to alleviate these issues and can significantly enhance therapeutic loading, delivery, and cancer targetability. Peptide systems can be tailor-made for specific cancer applications. This review describes three peptide classes, targeting, cell penetrating, and fusogenic peptides, as stand-alone nanoparticle systems, conjugations to nanoparticle systems, or as the therapeutic modality. Peptide nanoparticle design, characteristics, and applications are discussed as well as peptide applications in the clinical space.

Schistosoma mansoni Adult Worm Protective and Diagnostic Proteins in n-Butanol Extracts Revealed by Proteomic Analysis

The S. mansoni adult worm n-butanol extract (Sm-AWBE) has been previously shown to contain specific S. mansoni antigens that have been used for immunodiagnosis of schistosomiasis in solid phase alkaline phosphatase immunoassay (APIA) and western blot (WB) analyses. Sm-AWBE was also used in immunoprotection studies against a fatal live-cercariae challenge in experimental mouse vaccination (~43% protection). The Sm-AWBE fraction was prepared by mixing adult worm membranous suspensions with aqueous-saturated n-butanol, centrifuging and recovering n-butanol-resistant proteins in the aqueous phase. Here we report a preliminary identification of Sm-AWBE protein components as revealed from a qualitative proteomic study after processing Sm-AWBE by 1D-gel electrophoresis, in-gel and in-solution tryptic digestions, and mass spectrometry analyses. We identified 33 proteins in Sm-AWBE, all previously known S. mansoni proteins and antigens; among them, immunomodulatory proteins and proteins mostly involved in host–parasite interactions. About 81.8% of the identified Sm-AWBE proteins are antigenic. STRING analysis showed a set of Sm-AWBE proteins configuring a small network of interactive proteins and a group of proteins without interactions. Functional groups of proteins included muscle contraction, antioxidant, GPI-anchored phosphoesterases, regulatory 14-3-3, various enzymes and stress proteins. The results widen the possibilities to design novel antigen combinations for better diagnostic and immunoprotective strategies for schistosomiasis control.

Analysis of Intestinal Microflora and Metabolites From Mice With DSS-Induced IBD Treated With Schistosoma Soluble Egg Antigen

Objective: This study aimed to analyze the changes in intestinal flora and metabolites in the intestinal contents of mice with inflammatory bowel disease (IBD) to preliminarily clarify the mechanism of action of Schistosoma soluble egg antigen (SEA) on IBD, thus, laying a research foundation for the subsequent treatment of IBD. Methods: A total of 40 Institute of Cancer Research (ICR) mice were divided into four groups: control, SEA 50 μg, dextran sulfate sodium salt (DSS), and SEA 50 μg + DSS. The overall state of the animals was observed continuously during modeling. The colonic length was measured after 10 days of modeling. The degree of colonic inflammation was observed by hematoxylin and eosin staining. 16srRNA and liquid chromatography-mass spectrometry sequencing techniques were used to determine the abundance of bacteria and metabolites in the intestinal contents of mice in the DSS and SEA 50 μg + DSS groups, and the differences were further analyzed. Results: After SEA intervention, the disease activity index score of mice with IBD decreased and the colon shortening was reduced. Microscopically, the lymphocyte aggregation, glandular atrophy, goblet cell disappearance, and colonic inflammation were less in the SEA 50 μg + DSS group than in the DSS group (p < 0.0001). After SEA intervention, the abundance of beneficial bacteria prevotellaceae_UCG-001 was upregulated, while the abundance of the harmful bacteria Helicobacter, Lachnoclostridium, and Enterococcus was downregulated in the intestinal tract of mice with IBD. The intestinal metabolite analysis showed that SEA intervention decreased the intestinal contents of glycerophospholipids (lysophosphatidylcholine, lysophosphatidylethanolamine, phatidylcholine, and phatidylethanolamine) and carboxylic acids (L-alloisoleucine and L-glutamate), whereas increased bile acids and their derivatives (3B,7A,12a-trihydroxy-5A-cholanoic acid and 3A,4B, 12a-trihydroxy-5b-cholanoic acid). Combined microbiota-metabolite analysis revealed a correlation between these differential microbiota and differential metabolites. At the same time, the changes in the contents of metabolites and differential metabolites in the two groups also correlated with the abundance of the gut microbiome. Conclusions: The study showed that SEA reduced DSS-induced inflammation in IBD and improved the symptoms of IBD in mice through the combined regulation of intestinal flora and intestinal metabolism. It suggested a potential possibility for the use of SEA in treating and regulating intestinal flora and metabolism in patients with IBD.

Does Schistosoma Mansoni Facilitate Carcinogenesis?

Schistosomiasis is one of the most prominent parasite-induced infectious diseases, causing tremendous medical and socioeconomic problems. Current studies have reported on the spread of endemic regions and the fear of development of resistance against praziquantel, the only effective drug available. Among the Schistosoma species, only S. haematobium is classified as a Group 1 carcinogen (definitely cancerogenic to humans), causing squamous cell carcinoma of the bladder, whereas infection with S. mansoni is included in Group 3 of carcinogenic hazards to humans by the International Agency for Research on Cancer (IARC), indicating insufficient evidence to determine its carcinogenicity. Nevertheless, although S. mansoni has not been discussed as an organic carcinogen, the multiplicity of case reports, together with recent data from animal models and cell culture experiments, suggests that this parasite can predispose patients to or promote hepatic and colorectal cancer. In this review, we discuss the current data, with a focus on new developments regarding the association of S. mansoni infection with human cancer and the recently discovered biomolecular mechanisms by which S. mansoni may predispose patients to cancer development and carcinogenesis.

Eosinophils and helminth infection: protective or pathogenic?

Since the earliest descriptions of this enigmatic cell, eosinophils have been implicated in both protective and pathogenic immune responses to helminth infection. Nevertheless, despite substantial data from in vitro studies, human infections, and animal models, their precise role in helminth infection remains incompletely understood. This is due to a number of factors, including the heterogeneity of the many parasites included in the designation "helminth," the complexity and redundancy in the host immune response to helminths, and the pleiotropic functions of eosinophils themselves. This review examines the consequences of helminth-associated eosinophilia in the context of protective immunity, pathogenesis, and immunoregulation.

Nrf2 Participates in M2 Polarization by Trichinella spiralis to Alleviate TNBS-Induced Colitis in Mice

Trichinella spiralis induced alternative activated macrophages (M2), leading to protect against Crohn's disease, known as Th1 -related inflammation, which enhances oxidative stress in the host. However, the relationship of oxidative stress and T. spiralis -mediated immune response is still unknown. In our study, we showed that nuclear factor erythroid 2-related factor-2 (Nrf2), a key transcription factor in antioxidant, participated in M2 polarization induced by T. spiralis muscle larval excretory/secretory (ES) products in vitro. ES -treated M2 were injected intravenously after TNBS challenge and we demonstrated that ES-M could alleviate the severity of the colitis in mice. Adoptive transfer of ES -treated M2 decreased the level of IFN-γ and increased the levels of IL-4 and IL-10 in vivo. However, the capacity of ES -treated Nrf2 KO macrophages to treat colitis was dramatically impaired. ES -treated Nrf2 KO macrophages was insufficient to result in the elevated levels of IL-4 and IL-10. These findings indicate that Nrf2 was required for M2 polarization induced by T. spiralis ES to alleviate colitis in mice.

Allergological Importance of Invertebrate Glutathione Transferases in Tropical Environments

Glutathione-S transferases (GSTs) are part of a ubiquitous family of dimeric proteins that participate in detoxification reactions. It has been demonstrated that various GSTs induce allergic reactions in humans: those originating from house dust mites (HDM), cockroaches, and helminths being the best characterized. Evaluation of their allergenic activity suggests that they have a clinical impact. GST allergens belong to different classes: mu (Blo t 8, Der p 8, Der f 8, and Tyr p 8), sigma (Bla g 5 and Asc s 13), or delta (Per a 5). Also, IgE-binding molecules belonging to the pi-class have been discovered in helminths, but they are not officially recognized as allergens. In this review, we describe some aspects of the biology of GST, analyze their allergenic activity, and explore the structural aspects and clinical impact of their cross-reactivity.

Mining Helminths for Novel Therapeutics

Helminths are an emerging source of therapeutics for dysregulated inflammatory diseases. Excretory/secretory (ES) molecules, released during infection, are responsible for many of these immunomodulatory effects and are likely to have evolved as a means for parasite survival in the host. While the mechanisms of action of these molecules have not been fully defined, evidence demonstrates that they target various pathways in the immune response, ranging from initiation to effector cell modulation. These molecules are applied in controlling specific effector mechanisms of type 1 and type 2 immune responses. Recently, studies have further focused on their therapeutic potential in specific disease models. Here we review recent findings on ES molecule modulation of immune functions, specifically highlighting their clinical implications for future use in inflammatory disease therapeutics.

Schistosome Infection and Schistosome-Derived Products as Modulators for the Prevention and Alleviation of Immunological Disorders

Parasitic helminths, comprising the flatworms (tapeworms and flukes) and nematodes (roundworms), have plagued humans persistently over a considerable period of time. It is now known that the degree of exposure to these and other pathogens inversely correlates with the incidence of both T helper 1 (Th1)-mediated autoimmunity and Th2-mediated allergy. Accordingly, there has been recent increased interest in utilizing active helminth worm infections and helminth-derived products for the treatment of human autoimmune and inflammatory diseases and to alleviate disease severity. Indeed, there is an accumulating list of novel helminth derived molecules, including proteins, peptides, and microRNAs, that have been shown to exhibit therapeutic potential in a variety of disease models. Here we consider the blood-dwelling schistosome flukes, which have evolved subtle immune regulatory mechanisms that promote parasite survival but at the same time minimize host tissue immunopathology. We review and discuss the recent advances in using schistosome infection and schistosome-derived products as therapeutics to treat or mitigate human immune-related disorders, including allergic asthma, arthritis, colitis, diabetes, sepsis, cystitis, and cancer.

A comparative proteomics analysis of the egg secretions of three major schistosome species

Morbidity associated with hepatic and urogenital schistosomiasis stems primarily from the host immune response directed against schistosome eggs. When eggs become entrapped in host tissues, the development of fibrotic plaques drives downstream pathology. These events occur due to the antigenic nature of egg excretory/secretory products (ESPs). Both Schistosoma mansoni and S. japonicum ESPs have been shown to interact with several cell populations in the host liver including hepatocytes, macrophages, and hepatic stellate cells, with both immunomodulatory and pathological consequences. Several protein components of the ESPs of S. mansoni and S. japonicum eggs have been characterised; however, studies into the collective contents of schistosome egg ESPs are lacking. Utilising shotgun mass spectrometry and an array of in silico analyses, we identified 266, 90 and 50 proteins within the S. mansoni, S. japonicum and S. haematobium egg secretomes respectively. We identified numerous proteins with already established immunomodulatory activities, vaccine candidates and vesicle markers. Relatively few common orthologues within the ESPs were identified by BLAST, indicating that the three egg secretomes differ in content significantly. Having a clearer understanding of these components may lead to the identification of new proteins with uncharacterised immunomodulatory potential or pathological relevance. This will enhance our understanding of host-parasite interactions, particularly those occurring during chronic schistosomiasis, and pave the way towards novel therapeutics and vaccines.

Clinical Use of Schistosoma mansoni Antigens as Novel Immunotherapies for Autoimmune Disorders

The hygiene hypothesis states that improved hygiene and the resulting disappearance of once endemic diseases is at the origin of the enormous increase in immune related disorders such as autoimmune diseases seen in the industrialized world. Helminths, such as Schistosoma mansoni, are thought to provide protection against the development of autoimmune diseases by regulating the host's immune response. This modulation primarily involves induction of regulatory immune responses, such as generation of tolerogenic dendritic cells and alternatively activated macrophages. This points toward the potential of employing helminths or their products/metabolites as therapeutics for autoimmune diseases that are characterized by an excessive inflammatory state, such as multiple sclerosis (MS), type I diabetes (T1D) and inflammatory bowel disease (IBD). In this review, we examine the known mechanisms of immune modulation by S. mansoni, explore preclinical and clinical studies that investigated the use of an array helminthic products in these diseases, and propose that helminthic therapy opens opportunities in the treatment of chronic inflammatory disorders.

Systematic review: gastrointestinal infection and incident inflammatory bowel disease

BACKGROUND

The initiating events of chronic gastrointestinal (GI) inflammation in Crohn's disease (CD) and ulcerative colitis (UC) are not well-defined, but GI infections are implicated.

AIMS

To define the role of GI infections in risk of incident inflammatory bowel disease (IBD) and synthesise the current body of relevant translational data to provide biological context for associations between GI infections and IBD risk.

METHODS

We systematically reviewed electronic databases through February 2020. Clinical studies that provided risk estimates of the association between GI infections and incident IBD were included. Inclusion criteria were broader for translational studies aiming to define mechanisms of GI infections and predisposition to or protection from IBD.

RESULTS

Of the studies identified, 63 met full inclusion criteria. Among studies of clinical gastroenteritis, bacteria-specifically, Salmonella species, Campylobacter species and Clostridioides difficile-demonstrated consistent positive associations with risk of incident IBD. Of viruses, norovirus was associated with increased risk of incident CD. Regarding inverse associations with incident IBD, Helicobacter pylori and helminth infections were associated with a generally consistent reduced risk of IBD. Based on a qualitative analysis of the translational data, putative mechanisms involve multiple microbial and immunologic pathways.

CONCLUSIONS

Based on this systematic review, certain enteric pathogens are associated with an increased risk of incident IBD, while others are potentially protective. Prospective studies are required to clarify the clinical implications of these enteric pathogens on the risk and course of IBD, and possible therapeutic or preventative benefit.

Potential application of helminth therapy for resolution of neuroinflammation in neuropsychiatric disorders

Neuropsychiatric disorders (NPDs) are among the major debilitating disorders worldwide with multiple etiological factors. However, in recent years, psychoneuroimmunology uncovered the role of inflammatory condition and autoimmune disorders in the etiopathogenesis of different NPDs. Hence, resolution of inflammation is a new therapeutic target of NPDs. On the other hand, Helminth infections are among the most prevalent infectious diseases in underdeveloped countries, which usually caused chronic infections with minor clinical symptoms. Remarkably, helminths are among the master regulator of inflammatory reactions and epidemiological studies have shown an inverse association between prevalence of autoimmune disorders with these infections. As such, changes of intestinal microbiota are known to be associated with inflammatory conditions in various NPDs. Conversely, helminth colonization alters the intestinal microbiota composition that leads to suppression of intestinal inflammation. In animal models and human studies, helminths or their antigens have shown to be protected against severe autoimmune and allergic disorders, decline the intensity of inflammatory reactions and improved clinical symptoms of the patients. Therefore, "helminthic therapy" have been used for modulation of immune disturbances in different autoimmunity illnesses, such as Multiple Sclerosis (MS) and Inflammatory Bowel Disease (IBD). Here, it is proposed that "helminthic therapy" is able to ameliorate neuroinflammation of NPDs through immunomodulation of inflammatory reactions and alteration of microbiota composition. This review discusses the potential application of "helminthic therapy" for resolution of neuroinflammation in NPDs.

Safety of P28GST, a Protein Derived from a Schistosome Helminth Parasite, in Patients with Crohn's Disease: A Pilot Study (ACROHNEM)

Despite the development of novel therapies, inflammatory bowel diseases remain an innovative treatment challenge. Helminth therapy is a new promising approach, and a key issue is the identification of helminth-derived anti-inflammatory mediators. P28 glutathione-S-transferase (P28GST), a protein derived from schistosomes, a trematode parasitic helminth, was shown to reduce intestinal inflammation in experimental colitis by down-regulating the Th1/Th17 response. In this multicenter, open-label, pilot Phase 2a study, we evaluated the safety of P28GST administered to patients with mild Crohn’s disease (CD). We enrolled 10 patients with a baseline Crohn’s disease activity index (CDAI) value <220. Eight patients received two to three subcutaneous injections of recombinant P28GST with adjuvant. This three-month treatment was followed by a nine-month monitoring period. The primary endpoints were the monthly rate and seriousness of adverse events (AEs). Secondary endpoints were clinical recurrence, assessed with the CDAI as well as the levels of immunologic and inflammatory blood and tissue markers. The most common AEs were local or regional events at the injection site and gastrointestinal disorders. At three months after the first injection, CDAI scores and blood calprotectin levels decreased in parallel. These results indicate that P28GST showed promise as a safe and new therapeutic option for treating CD.

Glutathione-S-transferase of Trichinella spiralis regulates maturation and function of dendritic cells

Immunomodulation by molecules from Trichinella spiralis (T. spiralis) has been widely reported. Glutathione-S-transferase (GST) is a major immune-modulator of the family of detoxification enzymes. Dendritic cells (DCs) are an important target for the regulation of the immune response by T. spiralis. In this study, the recombinant GST of T. spiralis (rTs-GST) was expressed and purified. rTs-GST induced low CD40 expression and moderate CD80, CD86 and MHC-II expressions and inhibited the increase of CD40, CD80 and CD86 on DCs induced by LPS. We showed that rTs-GST decreased the LPS-induced elevated level of pro-inflammatory cytokines of DCs and enhanced the level of regulatory cytokines IL-10 and TGF-β. Furthermore, co-culture of DCs and CD4+ T cells demonstrated that rTs-GST-treated DCs suppressed the proliferation of OVA-specific CD4+ T cells and increased the population of regulatory T cells (Tregs). rTs-GST-treated DCs induced a higher level of IL-4, IL-10 and TGF-β, but inhibited the level of IFN-γ. This indicates that rTs-GST-pulsed DCs induce both Th2-type responses and Tregs. These findings contribute to the current understanding of the immunomodulation of Ts-GST on cellular response and immunomodulation of T. spiralis.

Contribution of the Gut Microbiota in P28GST-Mediated Anti-Inflammatory Effects: Experimental and Clinical Insights

An original immuno-regulatory strategy against inflammatory bowel diseases based on the use of 28 kDa glutathione S-transferase (P28GST), a unique schistosome protein, was recently proposed. Improvement of intestinal inflammation occurs through restoration of the immunological balance between pro-inflammatory T-helper 1 (Th1) responses and both T-helper 2 (Th2) and regulatory responses. However, detailed mechanisms explaining how P28GST prevents colitis and promotes gut homeostasis remain unknown. Considering the complex interplay between the adaptive and innate immune system and the intestinal microbiota, we raised the question of the possible role of the microbial ecosystem in the anti-inflammatory effects mediated by the helminth-derived P28GST protein. We first analyzed, by 16S rRNA sequencing, the bacterial profiles of mice fecal microbiota at several time points of the P28GST-immunomodulation period prior to trinitrobenzene sulfonic acid (TNBS)-colitis. The influence of gut microbiota in the P28GST-mediated anti-inflammatory effects was then assessed by fecal microbiota transplantation experiments from P28GST-immunized mice to either conventional or microbiota depleted naïve recipient mice. Finally, the experimental data were supplemented by the temporal fecal microbiota compositions of P28GST-treated Crohn’s disease patients from a pilot clinical study (NCT02281916). The P28GST administration slightly modulated the diversity and composition of mouse fecal microbiota while it significantly reduced experimental colitis in mice. Fecal microbiota transplantation experiments failed to restore the P28GST-induced anti-inflammatory effects. In Crohn’s disease patients, P28GST also induced slight changes in their overall fecal bacterial composition. Collectively, these results provide key elements in both the anti-inflammatory mechanisms and the safe therapeutic use of immunomodulation with such promising helminth-derived molecules.

Dendritic cells treated by Trichinella spiralis muscle larval excretory/secretory products alleviate TNBS-induced colitis in mice

BACKGROUND

Therapeutic potential of helminth have been shown to have a protective effect on immune-mediated diseases such as Crohn's disease (CD), which is associated with increased production of T helper cell type 1. However, helminth therapy is unacceptable to patients due to side-effects and the fear of parasites. As helminths regulate the cellular immune responses through innate cells such as dendritic cells (DCs), cellular immunotherapy has been considered a therapeutic option to treat CD.

METHODS

Bone marrow-dendritic cells were generated, enriched and treated with Trichinella spiralis muscle larval excretory/secretory products (Ts-MLES). DCs maturation was measured by flow cytometry and cytokine production of DCs were measured by ELISA. Colitis was generated by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) solution. For adoptive transfer, Ts-MLES treated-DCs injected intravenously 24 h prior to TNBS challenge. Disease activity index (DAI) including weight loss, diarrhea, and bloody stool were measured. Colon segments were stained with hematoxylin and eosin (H.E.) and periodic acid schiff (PAS) staining for histological damage scoring. The relative mRNA expression of cytokines in colon was analyzed by RT-PCR. Cytokine production in colon was measured by ELISA. Splenocytes were separated and cytokine profiles including Th1 (IFN-γ), Th2 (IL-4, IL-13), and Treg subsets (IL-10, TGF-β) were analyzed by flow cytometry.

RESULTS

Ts-MLES regulated the maturation and cytokine production of DCs. Ts-MLES -DC ameliorated the severity of the TNBS-induced colitis. In the colon and the spleen, Ts-MLES-DC decreased IFN-γ (Th1) significantly and increased Th2 (IL-4, IL-13)- and Treg (IL-10, TGF-β)- related cytokines.

CONCLUSIONS

Ts-MLES-DC ameliorated the severity of the TNBS-induced colitis through decreasing IFN-γ. Ts-MLES-DC skewed the Th1-mediated response toward the Th2 type and regulatory T cell response.

Treatment with P28GST, a schistosome-derived enzyme, after acute colitis induction in mice: Decrease of intestinal inflammation associated with a down regulation of Th1/Th17 responses

Background

P28GST, a 28Kd glutathione S-transferase enzymatic protein derived from a schistosome helminth prevents experimental colitis when administered subcutaneously in the presence of adjuvant by decreasing pro-inflammatory Th1/Th17 response. Given the antioxidant properties of P28GST, we evaluated its anti-inflammatory potential when administered locally after colitis induction in the absence of adjuvant.

Methods

Colitis was induced in BALB/c mice by rectal administration of TNBS, followed by two intraperitoneal injections of P28GST at day 1 and day 2. Mice were sacrificed 48h after TNBS administration and evaluated for macroscopic and histological scores, myeloperoxidase (MPO) quantification and cytokine messenger RNA expression in the colonic tissues.

Results

Both clinical and histological scores significantly decreased in mice treated with P28GST at 5 or 50μg/kg when compared to vehicle- treated mice. A significant reduction of MPO was detected in colonic tissues from P28GST–treated mice, similarly to mice treated with methylprednisolone as the reference treatment. Pro-inflammatory cytokines TNF, IL-1β, and IL-6, mRNA as well as serum levels were down-regulated in mice colonic tissues treated with P28GST at 5 or 50μg/kg. In addition, a significant decrease of mRNA expression levels of T-bet, and ROR-γ, respective markers of Th1 and Th17 cells was observed. Whereas no significant effect was detected on Gata3 mRNA, a marker of Th2 cells, the Arg/iNOS mRNA levels significantly increased in P28GST-treated mice, suggesting the induction of M2 macrophages.

Conclusions

These findings provide evidence that P28GST injected locally after colitis induction induces a potent decrease of colitis inflammation in mice, associated to downregulation of Th1/Th17 response, and induction of anti-inflammatory alternatively activated macrophages.

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.

Immunomodulatory tetracyclines shape the intestinal inflammatory response inducing mucosal healing and resolution

BACKGROUND AND PURPOSE

Immunomodulatory tetracyclines are well-characterized drugs with a pharmacological potential beyond their antibiotic properties. Specifically, minocycline and doxycycline have shown beneficial effects in experimental colitis, although pro-inflammatory actions have also been described in macrophages. Therefore, we aimed to characterize the mechanism behind their effect in acute intestinal inflammation.

EXPERIMENTAL APPROACH

A comparative pharmacological study was initially used to elucidate the most relevant actions of immunomodulatory tetracyclines: doxycycline, minocycline and tigecycline; other antibiotic or immunomodulatory drugs were assessed in bone marrow-derived macrophages and in dextran sodium sulfate (DSS)-induced mouse colitis, where different barrier markers, inflammatory mediators, microRNAs, TLRs, and the gut microbiota composition were evaluated. The sequential immune events that mediate the intestinal anti-inflammatory effect of minocycline in DSS-colitis were then characterized.

KEY RESULTS

Novel immunomodulatory activity of tetracyclines was identifed; they potentiated the innate immune response and enhanced resolution of inflammation. This is also the first report describing the intestinal anti-inflammatory effect of tigecycline. A minor therapeutic benefit seems to derive from their antibiotic properties. Conversely, immunomodulatory tetracyclines potentiated macrophage cytokine release in vitro, and while improving mucosal recovery in colitic mice, they up-regulated Ccl2, miR-142, miR-375 and Tlr4. In particular, minocycline initially enhanced IL-1β, IL-6, IL-22, GM-CSF and IL-4 colonic production and monocyte recruitment to the intestine, subsequently increasing Ly6C^- MHCII⁺ macrophages, Tregs and type 2 intestinal immune responses.

CONCLUSIONS AND IMPLICATIONS

Immunomodulatory tetracyclines potentiate protective immune pathways leading to mucosal healing and resolution, representing a promising drug reposition strategy for the treatment of intestinal inflammation.

Assessment of Fasciola hepatica glutathione S-transferase as an antigen for serodiagnosis of human chronic fascioliasis

Due to the unsatisfactory performance of parasitological diagnosis of human fascioliasis; the use of immunodiagnosis based on the detection of anti-Fasciola antibodies is traditionally used as a diagnostic alternative using total or purified parasite excretory-secretory products (ESPs). Glutathione S-transferase (GST) protein, one of the F. hepatica ESP components, possesses well-known roles in the detoxification of xenobiotic and endogenously derived toxins within the host bile environment. GST has shown to be a good target for vaccine or drug development against fascioliasis. The current study aimed to evaluate the potential of GST protein purified from a soluble crude extract of adult flukes as an antigen for serodiagnosis of chronic human fascioliasis by indirect ELISA. The study included a panel of 116 serum samples collected from individuals with confirmed fascioliasis, individuals carrying heterologous parasitic infections and healthy subjects. The parasitological examination was used as gold standard and a previously optimized ESP-ELISA was used to compare the performance of the GST-ELISA method. Results demonstrated that GST-ELISA is 94.3% sensitive, 80.2% specific and exhibits a moderate positive correlation (r = 0.555) and substantial agreement (k = 0.786) with the results obtained with the ESP-ELISA method. Moreover, because no sera from patients with early F. hepatica infection were available, GST-ELISA was then tested with sera from rabbits experimentally infected with F. hepatica metacercariae. The assay was able to detect anti-Fasciola antibodies as early as the 3^rd week of infection (p < 0.0001) with peaks at 4^th and 10^th week post-infection.

The Untapped Pharmacopeic Potential of Helminths

The dramatic rise in immunological disorders that occurs with socioeconomic development is associated with alterations in microbial colonization and reduced exposure to helminths. Excretory-secretory (E/S) helminth products contain a mixture of proteins and low-molecular-weight molecules representing the primary interface between parasite and host. Research has shown great pharmacopeic potential for helminth-derived products in animal disease models and even in clinical trials. Although in its infancy, the translation of worm-derived products into therapeutics is highly promising. Here, we focus on important key aspects in the development of immunomodulatory drugs, also highlighting novel approaches that hold great promise for future development of innovative research strategies.

Parasite-Derived Proteins for the Treatment of Allergies and Autoimmune Diseases

The morbidity associated with atopic diseases and immune dysregulation disorders such as asthma, food allergies, multiple sclerosis, atopic dermatitis, type 1 diabetes mellitus, and inflammatory bowel disease has been increasing all around the world over the past few decades. Although the roles of non-biological environmental factors and genetic factors in the etiopathology have been particularly emphasized, they do not fully explain the increase; for example, genetic factors in a population change very gradually. Epidemiological investigation has revealed that the increase also parallels a decrease in infectious diseases, especially parasitic infections. Thus, the reduced prevalence of parasitic infections may be another important reason for immune dysregulation. Parasites have co-evolved with the human immune system for a long time. Some parasite-derived immune-evasion molecules have been verified to reduce the incidence and harmfulness of atopic diseases in humans by modulating the immune response. More importantly, some parasite-derived products have been shown to inhibit the progression of inflammatory diseases and consequently alleviate their symptoms. Thus, parasites, and especially their products, may have potential applications in the treatment of autoimmune diseases. In this review, the potential of parasite-derived products and their analogs for use in the treatment of atopic diseases and immune dysregulation is summarized.

Orally administered Taenia solium Calreticulin prevents experimental intestinal inflammation and is associated with a type 2 immune response

Intestinal helminth antigens are inducers of type 2 responses and can elicit regulatory immune responses, resulting in dampened inflammation. Several platyhelminth proteins with anti-inflammatory activity have been reported. We have identified, cloned and expressed the Taenia solium calreticulin (rTsCRT) and shown that it predominantly induces a type 2 response characterized by IgG1, IL-4 and IL-5 production in mice. Here, we report the rTsCRT anti-inflammatory activity in a well-known experimental colitis murine model. Mice were orally immunized with purified rTsCRT and colitis was induced with trinitrobenzene sulfonic acid (TNBS). Clinical signs of disease, macroscopic and microscopic tissue inflammation, cytokine production and micronuclei formation, as a marker of genotoxicity, were measured in order to assess the effect of rTsCRT immunization on experimentally induced colitis. rTsCRT administration prior to TNBS instillation significantly reduced the inflammatory parameters, including the acute phase cytokines TNF-α, IL-1β and IL-6. Dampened inflammation was associated with increased local expression of IL-13 and systemic IL-10 and TGF-β production. Genotoxic damage produced by the inflammatory response was also precluded. Our results show that oral treatment with rTsCRT prevents excessive TNBS-induced inflammation in mice and suggest that rTsCRT has immunomodulatory properties associated with the expression of type 2 and regulatory cytokines commonly observed in other helminths.

Preparation and investigation of P28GST-loaded PLGA microparticles for immunomodulation of experimental colitis

The aim of this work was to prepare and characterize (in vitro and in vivo) PLGA-based microparticles loaded with an enzymatic protein derived from the helminth parasite Schistosoma haematobium: glutathione S-transferase P28GST (P28GST). This protein is not only a promising candidate vaccine against schistosomiasis, it also exhibits interesting immunomodulating effects, which can be helpful for the regulation of inflammatory diseases. Helminths express a regulatory role on intestinal inflammation, and immunization by P28GST has recently been shown to be as efficient as infection to reduce inflammation in a murine colitis model. As an alternative to the combination with a classical adjuvant, long acting P28GST microparticles were prepared in order to induce colitis prevention. PLGA was used as biodegradable and biocompatible matrix former, and a W/O/W emulsion/solvent extraction technique applied to prepare different types of microparticles. The effects of key formulation and processing parameters (e.g., the polymer molecular weight, drug loading, W/O/W phase volumes and stirring rates of the primary/secondary emulsions) on the systems' performance were studied. Microparticles providing about constant P28GST release during several weeks were selected and their effects in an experimental model of colitis evaluated. Mice received P28GST-loaded or P28GST-free PLGA microparticles (s.c.) on Day 0, and optionally also on Days 14 and 28. Colitis was induced on Day 35, the animals were sacrificed on Day 37. Interestingly, the Wallace score (being a measure of the severity of the inflammation) was significantly lower in mice treated with P28GST microparticles compared to placebo after 1 or 3 injections. As immunogenicity markers, increased anti-P28GST IgG levels were detected after three P28GST PLGA microparticle injections, but not in the control groups. Thus, the proposed microparticles offer an interesting potential for the preventive treatment of experimental colitis, while the underlying mechanism of action is still to be investigated.

Helminths in the gastrointestinal tract as modulators of immunity and pathology

Helminth parasites are highly prevalent in many low- and middle-income countries, in which inflammatory bowel disease and other immunopathologies are less frequent than in the developed world. Many of the most common helminths establish themselves in the gastrointestinal tract and can exert counter-inflammatory influences on the host immune system. For these reasons, interest has arisen as to how parasites may ameliorate intestinal inflammation and whether these organisms, or products they release, could offer future therapies for immune disorders. In this review, we discuss interactions between helminth parasites and the mucosal immune system, as well as the progress being made toward identifying mechanisms and molecular mediators through which it may be possible to attenuate pathology in the intestinal tract.

Helminth Immunomodulation in Autoimmune Disease

Helminths have evolved to become experts at subverting immune surveillance. Through potent and persistent immune tempering, helminths can remain undetected in human tissues for decades. Redirecting the immunomodulating "talents" of helminths to treat inflammatory human diseases is receiving intensive interest. Here, we review therapies using live parasitic worms, worm secretions, and worm-derived synthetic molecules to treat autoimmune disease. We review helminth therapy in both mouse models and clinical trials and discuss what is known on mechanisms of action. We also highlight current progress in characterizing promising new immunomodulatory molecules found in excretory/secretory products of helminths and their potential use as immunotherapies for acute and chronic inflammatory diseases.

Proteomic Analysis of Excretory-Secretory Products of Mesocestoides corti Metacestodes Reveals Potential Suppressors of Dendritic Cell Functions

Accumulating evidences have assigned a central role to parasite-derived proteins in immunomodulation. Here, we report on the proteomic identification and characterization of immunomodulatory excretory-secretory (ES) products from the metacestode larva (tetrathyridium) of the tapeworm Mesocestoides corti (syn. M. vogae). We demonstrate that ES products but not larval homogenates inhibit the stimuli-driven release of the pro-inflammatory, Th1-inducing cytokine IL-12p70 by murine bone marrow-derived dendritic cells (BMDCs). Within the ES fraction, we biochemically narrowed down the immunosuppressive activity to glycoproteins since active components were lipid-free, but sensitive to heat- and carbohydrate-treatment. Finally, using bioassay-guided chromatographic analyses assisted by comparative proteomics of active and inactive fractions of the ES products, we defined a comprehensive list of candidate proteins released by M. corti tetrathyridia as potential suppressors of DC functions. Our study provides a comprehensive library of somatic and ES products and highlight some candidate parasite factors that might drive the subversion of DC functions to facilitate the persistence of M. corti tetrathyridia in their hosts.

The metacestode larval stages of life-threatening tapeworms grow within the organs of its mammalian hosts, thus causing severe and long-lasting morbidity. Immunosuppression, which mainly depends on factors that are released or leaking from the parasite, plays an important role in both survival and proliferation of the larvae. These parasite-derived molecules are potential targets for developing new anti-parasitic drugs and/or improving the effectiveness of current therapies. Moreover, an optimized use of such factors could help to minimize pathologies resulting from uncontrolled immune responses, like allergies and autoimmune diseases. The authors herein demonstrate that larvae from a parasitic cestode release factors that sufficiently support the suppression of dendritic cells, a set of innate immune cells that recognizes and initiates host immune responses against invading pathogens. Employing modern analytic proteomic tools combined with immunological bioassays, several cestode-derived candidate immunomodulators were identified. This is the first bioassay-guided comprehensive library of candidate immunomodulators from a tissue-dwelling cestode larva. This work validates the unmet value of the Mesocestoides corti system in characterizing the mechanisms of host immunomodulation by metacestodes and reveals the largest database of candidate metacestode-derived immunomodulators until date.

Immunity by equilibrium

The classical model of immunity posits that the immune system reacts to pathogens and injury and restores homeostasis. Indeed, a century of research has uncovered the means and mechanisms by which the immune system recognizes danger and regulates its own activity. However, this classical model does not fully explain complex phenomena, such as tolerance, allergy, the increased prevalence of inflammatory pathologies in industrialized nations and immunity to multiple infections. In this Essay, I propose a model of immunity that is based on equilibrium, in which the healthy immune system is always active and in a state of dynamic equilibrium between antagonistic types of response. This equilibrium is regulated both by the internal milieu and by the microbial environment. As a result, alteration of the internal milieu or microbial environment leads to immune disequilibrium, which determines tolerance, protective immunity and inflammatory pathology.

Differential Action between Schisandrin A and Schisandrin B in Eliciting an Anti-Inflammatory Action: The Depletion of Reduced Glutathione and the Induction of an Antioxidant Response

Schisandrin A (Sch A) and schisandrin B (Sch B) are active components of Schisandrae Fructus. We compared the biochemical mechanism underlying the anti-inflammatory action of Sch A and Sch B, using cultured lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and concanavalin (ConA)-stimulated mouse splenocytes. Pre-incubation with Sch A or Sch B produced an anti-inflammatory action in LPS-stimulated RAW264.7 cells, as evidenced by the inhibition of the pro-inflammatory c-Jun N-terminal kinases/p38 kinase/nuclear factor-κB signaling pathway as well as the suppression of various pro-inflammatory cytokines and effectors, with the extent of inhibition by Sch A being more pronounced. The greater activity of Sch A in anti-inflammatory response was associated with a greater decrease in cellular reduced glutathione (GSH) level and a greater increase in glutathione S-transferase activity than corresponding changes produced by Sch B. However, upon incubation, only Sch B resulted in the activation of the nuclear factor (erythroid-derived 2)-like factor 2 and the induction of a significant increase in the expression of thioredoxin (TRX) in RAW264.7 cells. The Sch B-induced increase in TRX expression was associated with the suppression of pro-inflammatory cytokines and effectors in LPS-stimulated macrophages. Studies in a mouse model of inflammation (carrageenan-induced paw edema) indicated that while long-term treatment with either Sch A or Sch B suppressed the extent of paw edema, only acute treatment with Sch A produced a significant degree of inhibition on the inflammatory response. Although only Sch A decreased the cellular GSH level and suppressed the release of pro-inflammatory cytokines and cell proliferation in ConA-simulated splenocytes in vitro, both Sch A and Sch B treatments, while not altering cellular GSH levels, suppressed ConA-stimulated splenocyte proliferation ex vivo. These results suggest that Sch A and Sch B may act differentially on activating GST/ depleting cellular GSH and inducing an antioxidant response involved in their anti-inflammatory actions.