Schistosoma japonicum cystatin attenuates murine collagen-induced arthritis

An update on proteases and protease inhibitors from trematodes

Trematodes, a class of parasitic flatworms, are responsible for a variety of devastating diseases in humans and animals, with schistosomiasis and fascioliasis being prominent examples. Trematode proteolytic systems involved in the host-parasite interaction have emerged as key contributors to the success of trematodes in establishing and maintaining infections. This review concentrates on diverse proteases and protease inhibitors employed by trematodes and provides an update on recent advances in their molecular-level characterization, with a focus on function, structure, and therapeutic target potential.

Functional analysis of novel cystatins from Haemaphysalis doenitzi and evaluation of their roles in cypermethrin and λ-cyhalothrin resistance

Currently, the primary strategy for tick control relies on chemical agents. Pyrethrins, which are botanically derived compounds, have demonstrated efficacy in controlling ticks without posing a risk to human or animal health. However, research into pyrethrins' metabolic mechanisms remains sparse. Cystatin, as a reversible binding inhibitor of cysteine protease, may be involved in the initiation of pyrethrin detoxification of Haemaphysalis doenitzi. In this study, two novel cystatins were cloned, HDcyst-3 and HDcyst-4, the relative expression of which was highest in the Malpighian tubules compared with the tick midguts, salivary glands, and ovaries. Prokaryotic expression and in vitro studies revealed that cystatins effectively inhibit the enzymatic activities of cathepsins B and S. RNAi results showed that the reduction of cystatins significantly decreased the engorgement weight, egg mass weight, and egg hatching rate of adult female ticks, and prolonged feeding time by two days. The control rate of rHDcyst-3 and rHDcyst-4 protein vaccination against female adults were 55.9% and 63.2%, respectively. In addition, the tick immersion test showed that cypermethrin and λ-cyhalothrin had significant acaricidal effects against adult unfed H. doenitzi. The qPCR result indicated that compared with the control group, the expression of HDcyst-3 and HDcyst-4 was markedly decreased in the sublethal cypermethrin and λ-cyhalothrin group at LC50. Enzyme activity showed that cypermethrin and λ-cyhalothrin could significantly induce the activities of glutathione S-transferase (GST), carboxylesterase (CarE), and acetylcholinesterase (AchE). The aforementioned results provided indirect evidence that cystatin plays an important role in pyrethrin detoxification and provides a theoretical basis for future acaricide experiments and pest management.

Solution structure of the N-terminal extension domain of a Schistosoma japonicum asparaginyl-tRNA synthetase

Several secreted proteins from helminths (parasitic worms) have been shown to have immunomodulatory activities. Asparaginyl-tRNA synthetases are abundantly secreted in the filarial nematode Brugia malayi (BmAsnRS) and the parasitic flatworm Schistosoma japonicum (SjAsnRS), indicating a possible immune function. The suggestion is supported by BmAsnRS alleviating disease symptoms in a T-cell transfer mouse model of colitis. This immunomodulatory function is potentially related to an N-terminal extension domain present in eukaryotic AsnRS proteins but few structure/function studies have been done on this domain. Here we have determined the three-dimensional solution structure of the N-terminal extension domain of SjAsnRS. A protein containing the 114 N-terminal amino acids of SjAsnRS was recombinantly expressed with isotopic labelling to allow structure determination using 3D NMR spectroscopy, and analysis of dynamics using NMR relaxation experiments. Structural comparisons of the N-terminal extension domain of SjAsnRS with filarial and human homologues highlight a high degree of variability in the β-hairpin region of these eukaryotic N-AsnRS proteins, but similarities in the disorder of the C-terminal regions. Limitations in PrDOS-based intrinsically disordered region (IDR) model predictions were also evident in this comparison. Empirical structural data such as that presented in our study for N-SjAsnRS will enhance the prediction of sequence-homology based structure modelling and prediction of IDRs in the future.Communicated by Ramaswamy H. Sarma.

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.

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.

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.

Trichinella spiralis cystatin alleviates polymicrobial sepsis through activating regulatory macrophages

BACKGROUND

Sepsis is a life-threateningorgandysfunction caused by the cytokine storm induced by the severe bacterial infection. Excessive inflammatory responses are responsible for the lethal organ damage during the early stage of sepsis. Helminth infection and helminth-derived proteins have been identified to have the ability to immunomodulate the host immune system by reducing inflammation against inflammatory diseases. Trichinella spiralis cystatin (Ts-Cys) is a cysteine protease inhibitor with strong immunomodulatory functions on host immune system. Our previous studies have shown that excretory-secretory proteins of T. spiralis reduced sepsis-induced inflammation and Ts-Cys was able to inhibit macrophages to produce inflammatory cytokines. Whether Ts-Cys has a therapeutic effect on polymicrobial sepsis and related immunological mechanism are not yet known.

METHODS

Sepsis was induced in BALB/c mice using cecal ligation and puncture (CLP), followed by intraperitoneal injection of 15 µg recombinant Ts-Cys (rTs-Cys). The therapeutic effect of rTs-Cys on sepsis was evaluated by observing the 72-hour survival rates of CLP-induced septic mice and the acute injury of lung and kidney through measuring the wet/dry weight ratio of lung, the levels of blood urea nitrogen (BUN) and creatinine (Cr) in sera and the tissue section pathology. The potential underlying mechanism was investigated using mouse bone marrow-derived macrophages (BMDMs) by observing the effect of rTs-Cys on LPS-stimulated macrophage polarization. The expression of genes associated with macrophage polarization in BMDMs and tissues of septic mice was measured by Western Blotting and qPCR.

RESULTS

In this study, we demonstrated the treatment with rTs-Cys alleviated CLP-induced sepsis in mice with significantly reduced pathological injury in vital organs of lung and kidney and reduced mortality of septic mice. The further study identified that treatment with rTs-Cys promoted macrophage polarization from classically activated macrophage (M1) to alternatively activated macrophage (M2) phenotype via inhibiting TLR2/MyD88 signal pathway and increasing expression of mannose receptor (MR), inhibited pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) and increased regulatory anti-inflammatory cytokines (IL-10 and TGF-β) in sera and tissues (lung and kidney) of mice with polymicrobial sepsis.

CONCLUSIONS

Our results demonstrated that rTs-Cys had a therapeutic effect on sepsis through activating regulatory macrophages possibly via suppressing TLR2/MyD88 signal pathway. We also identified that rTs-Cys-induced M2 macrophage differentiation was associated with increased expression of MR on the surface of macrophages. Our results underscored the importance of MR in regulating macrophages during the treatment with rTs-Cys, providing another immunological mechanism in which helminths and their derived proteins modulate the host immune system. The findings in this study suggest that rTs-Cys is a potential therapeutic agent for the prevention and treatment of sepsis and other inflammatory diseases.

The Protective Effect of the Soluble Egg Antigen of Schistosoma japonicum in A Mouse Skin Transplantation Model

Background

Organ transplantation is currently an effective method for treating organ failure. Long-term use of immunosuppressive drugs has huge side effects, which severely restricts the long-term survival of patients. Schistosoma can affect the host’s immune system by synthesizing, secreting, or excreting a variety of immunomodulatory molecules, but its role in transplantation was not well defined. In order to explore whether Schistosoma-related products can suppress rejection and induce long-term survival of the transplant, we used soluble egg antigen (SEA) of Schistosoma japonicum in mouse skin transplantation models.

Materials and methods

Each mouse was intraperitoneally injected with 100 μg of SEA three times a week for four consecutive weeks before allogenic skin transplant. Skin transplants were performed on day 0 to observe graft survival. Pathological examination of skin grafts was conducted 7 days post transplantation. The skin grafts were subjected to mRNA sequencing. Bioinformatics analysis was conducted and the expression of hub genes was verified by qPCR. Flow cytometry analysis was performed to evaluate the immune status and validate the results from bioinformatic analysis.

Results

The mean survival time (MST) of mouse skin grafts in the SEA-treated group was 11.67 ± 0.69 days, while that of the control group was 8.00 ± 0.36 days. Pathological analysis showed that Sj SEA treatment led to reduced inflammatory infiltration within skin grafts 7 days after allogenic skin transplantation. Bioinformatics analysis identified 86 DEGs between the Sj SEA treatment group and the control group, including 39 upregulated genes and 47 downregulated genes. Further analysis revealed that Sj SEA mediated regulation on cellular response to interferon-γ, activation of IL-17 signaling and chemokine signaling pathways, as well as cytokine–cytokine receptor interaction. Flow cytometry analysis showed that SEA treatment led to higher percentages of CD4⁺IL-4⁺ T cells and CD4⁺Foxp3⁺ T cells and decreased CD4⁺IFN-γ⁺ T cells in skin transplantation.

Conclusion

Sj SEA treatment suppressed rejection and prolonged skin graft survival by regulating immune responses. Sj SEA treatment might be a potential new therapeutic strategy to facilitate anti-rejection therapy and even to induce tolerance.

Therapeutic Effect of Schistosoma japonicum Cystatin on Atherosclerotic Renal Damage

Atherosclerosis is a chronic inflammation of the arterial vessel wall driven by lipid metabolism disorders. Although helminthic infection and their derivatives have been identified to attenuate the chronic inflammatory diseases, the immunomodulatory effect of recombinant Schistosoma japonicum cystatin (rSj-Cys) on metabolic diseases and atherosclerosis has not been reported. In this study, we investigated the therapeutic efficacy of rSj-Cys on atherosclerotic renal damage and explored the related immunological mechanism. The results demonstrated that treatment with rSj-Cys significantly reduced body weight gain, hyperlipidemia, and atherosclerosis induced by the high-fat diet in apoE^–/– mice. The treatment of rSj-Cys also significantly improved kidney functions through promoting macrophage polarization from M1 to M2, therefore inhibiting M1 macrophage–induced inflammation. The possible mechanism underlying the regulatory effect of rSj-Cys on reducing atherosclerosis and atherosclerotic renal damage is that rSj-Cys stimulates regulatory T cell and M2 macrophage polarization that produce regulatory cytokines, such as interleukin 10 and transforming growth factor β. The therapeutic effect of rSj-Cys on atherosclerotic renal damage is possibly through inhibiting the activation of TLR2/Myd88 signaling pathway. The results in this study provide evidence for the first time that Schistosoma-derived cystatin could be developed as a therapeutic agent to treat lipid metabolism disorder and atherosclerosis that threats million lives around the world.

Immune Function and Mechanism of Costimulating Molecules PD-1 and OX40 in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a T lymphocyte-mediated autoimmune disease, although its immune mechanism has not been fully studied. In this study, healthy controls (HC), osteoarthritis patients (OA), and RA patients were enrolled, and mice were evenly divided into control, collagen-induced arthritis (CIA), PD-1 Fc/CIA (PD-1 Fc membrane fusion protein administered to CIA mice), OX40 Fc/CIA (OX40 Fc membrane fusion protein administered to CIA mice), and PD-1 Fc + OX40 Fc/CIA groups. The expressions of programmed death-1 (PD-1) and OX40 in CD4⁺ T lymphocytes and the levels of sPD-1, immunoglobulin, and proinflammatory factors in patients and mice were measured. The results showed that the expression levels of PD-1 and OX40 in CD4⁺ T lymphocytes separated from the peripheral blood and synovial fluid of RA patients and the spleen of CIA mice were observably elevated. The levels of soluble PD-1, interleukin (IL)-2, IL-4, IL-5, IL-17, and interferon-γ (IFN-γ) in RA patients obviously increased. In animal experiments, PD-1 Fc not only increased the serum levels of immunoglobulin G (IgG), IgG1, and IgG2a in CIA mice, but also increased the levels of IL-4, IL-2, IL-5, IL-17, and IFN-γ in mouse spleen cells and joint tissues, which, however, were reversed by OX40 Fc. In conclusion, OX40 inhibition could reverse the progression of RA caused by PD-1 blocking, and PD-1 might be a potential target for RA. Clinical Trials.gov ID: HGH2018012203.

Immunomics-Guided Antigen Discovery for Praziquantel-Induced Vaccination in Urogenital Human Schistosomiasis

Despite the enormous morbidity attributed to schistosomiasis, there is still no vaccine to combat the disease for the hundreds of millions of infected people. The anthelmintic drug, praziquantel, is the mainstay treatment option, although its molecular mechanism of action remains poorly defined. Praziquantel treatment damages the outermost surface of the parasite, the tegument, liberating surface antigens from dying worms that invoke a robust immune response which in some subjects results in immunologic resistance to reinfection. Herein we term this phenomenon Drug-Induced Vaccination (DIV). To identify the antigenic targets of DIV antibodies in urogenital schistosomiasis, we constructed a recombinant proteome array consisting of approximately 1,000 proteins informed by various secretome datasets including validated proteomes and bioinformatic predictions. Arrays were screened with sera from human subjects treated with praziquantel and shown 18 months later to be either reinfected (chronically infected subjects, CI) or resistant to reinfection (DIV). IgG responses to numerous antigens were significantly elevated in DIV compared to CI subjects, and indeed IgG responses to some antigens were completely undetectable in CI subjects but robustly recognized by DIV subjects. One antigen in particular, a cystatin cysteine protease inhibitor stood out as a unique target of DIV IgG, so recombinant cystatin was produced, and its vaccine efficacy assessed in a heterologous Schistosoma mansoni mouse challenge model. While there was no significant impact of vaccination with adjuvanted cystatin on adult worm numbers, highly significant reductions in liver egg burdens (45-55%, P<0.0001) and intestinal egg burdens (50-54%, P<0.0003) were achieved in mice vaccinated with cystatin in two independent trials. This study has revealed numerous antigens that are targets of DIV antibodies in urogenital schistosomiasis and offer promise as subunit vaccine targets for a drug-linked vaccination approach to controlling schistosomiasis.

Schistosome infection promotes osteoclast-mediated bone loss

Infection with schistosome results in immunological changes that might influence the skeletal system by inducing immunological states affecting bone metabolism. We investigated the relationships between chronic schistosome infection and bone metabolism by using a mouse model of chronic schistosomiasis, affecting millions of humans worldwide. Results showed that schistosome infection resulted in aberrant osteoclast-mediated bone loss, which was accompanied with an increased level of receptor activator of nuclear factor-κB (NF-κB) Ligand (RANKL) and decreased level of osteoprotegerin (OPG). The blockade of RANKL by the anti-RANKL antibody could prevent bone loss in the context of schistosome infection. Meanwhile, both B cells and CD4⁺ T cells, particularly follicular helper T (Tfh) cell subset, were the important cellular sources of RANKL during schistosome infection. These results highlight the risk of bone loss in schistosome-infected patients and the potential benefit of coupling bone therapy with anti-schistosome treatment.

Schistosomiasis remains an important public health problem in many countries in tropical and subtropical regions, which affects about 200 million people worldwide, with another 700 million considered at risk of infection. Although the primary cause of pathogenesis of schistosomiasis is the granulomatous inflammatory responses, schistosomiasis patients experience long-term hidden pathologies that remain poorly investigated. Here, we found that schistosome infection resulted in RANKL-associated bone loss. Furthermore, our results indicated that both B cells and CD4⁺ T cells, particularly Tfh cell subset, in the peripheral lymphoid tissues are likely to be the important contributors to bone loss through releasing soluble RANKL. In addition, Tfh cells played a sufficient but not necessary role in schistosome infection-induced bone loss. Our findings highlight the risk of bone loss in schistosome-infected patients and the potential benefit of coupling bone therapy with anti-schistosome treatment.

Schistosoma japonicum Cystatin Alleviates Sepsis Through Activating Regulatory Macrophages

Multi-organ failure caused by the inflammatory cytokine storm induced by severe infection is the major cause of death for sepsis. Sj-Cys is a cysteine protease inhibitor secreted by Schistosoma japonicum with strong immunomodulatory functions on host immune system. Our previous studies have shown that treatment with Sj-Cys recombinant protein (rSj-Cys) attenuated inflammation caused by sepsis. However, the immunological mechanism underlying the immunomodulation of Sj-Cys for regulating inflammatory diseases is not yet known. In this study, we investigated the effect of Sj-Cys on the macrophage M2 polarization and subsequent therapeutic effect on sepsis. The rSj-Cys was expressed in yeast Pichia pastoris. Incubation of mouse bone marrow-derived macrophages (BMDMs) with yeast-expressed rSj-Cys significantly activated the polarization of macrophages to M2 subtype characterized by the expression of F4/80⁺ CD206⁺ with the elated secretion of IL-10 and TGF-β. Adoptive transfer of rSj-Cys treated BMDMs to mice with sepsis induced by cecal ligation and puncture (CLP) significantly improved their survival rates and the systemic clinical manifestations of sepsis compared with mice receiving non-treated normal BMDMs. The therapeutic effect of Sj-Cys-induced M2 macrophages on sepsis was also reflected by the reduced pathological damages in organs of heart, lung, liver and kidney and reduced serological levels of tissue damage-related ALT, AST, BUN and Cr, associated with downregulated pro-inflammatory cytokines (IFN-gamma and IL-6) and upregulated regulatory anti-inflammatory cytokines (IL-10 and TGF-β). Our results demonstrated that Sj-Cys is a strong immunomodulatory protein with anti-inflammatory features through activating M2 macrophage polarization. The findings of this study suggested that Sj-Cys itself or Sj-Cys-induced M2 macrophages could be used as therapeutic agents in the treatment of sepsis or other inflammatory diseases.

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.

The Potential Role of Schistosome-Associated Factors as Therapeutic Modulators of the Immune System

The parasites and eggs of helminths, including schistosomes, are associated with factors that can modulate the nature and outcomes of host immune responses, particularly enhancing type 2 immunity and impairing the effects of type 1 and type 17 immunity. The main species of schistosomes that cause infection in humans are capable of generating a microenvironment that allows survival of the parasite by evasion of the immune response. Schistosome infections are associated with beneficial effects on chronic immune disorders, including allergies, autoimmune diseases, and alloimmune responses. Recently, there has been increasing research interest in the role of schistosomes in immunoregulation during human infection, and the mechanisms underlying these roles continue to be investigated. Further studies may identify potential opportunities to develop new treatments for immune disease. In this review, we provide an update on the advances in our understanding of schistosome-associated modulation of the cells of the innate and adaptive immune systems as well as the potential role of schistosome-associated factors as therapeutic modulators of immune disorders, including allergies, autoimmune diseases, and transplant immunopathology. We also discuss potential opportunities for targeting schistosome-induced immunoregulation for future translation to the clinical setting.

Parasite Cystatin: Immunomodulatory Molecule with Therapeutic Activity against Immune Mediated Disorders

The use of parasites or their products for treating chronic inflammation associated diseases (CIADs) has generated significant attention recently. Findings from basic and clinical research have provided valuable information on strengthening the notion that parasites' molecules can be developed as biotherapeutic agents. Completion of the genome, secreotome, and proteome of the parasites has provided an excellent platform for screening and identifying several host immunomodulatory molecules from the parasites and evaluate their therapeutic potential for CIADs. One of the widely studied host immunomodulatory molecules of the parasites is the cysteine protease inhibitor (cystatin), which is primarily secreted by the parasites to evade host immune responses. In this review, we have attempted to summarize the findings to date on the use of helminth parasite-derived cystatin as a therapeutic agent against CIADs. Although several studies suggest a role for alternatively activated macrophages, other regulatory cells, and immunosuppressive molecules, in this immunoregulatory activity of the parasite-derived cystatin, there is still no clear demonstration as to how cystatin induces its anti-inflammatory effect in suppressing CIADs.

Therapeutic efficacy of Schistosoma japonicum cystatin on sepsis-induced cardiomyopathy in a mouse model

BACKGROUND

Myocardial dysfunction is one of the most common complications of multiple organ failure in septic shock and significantly increases mortality in patients with sepsis. Although many studies having confirmed that helminth-derived proteins have strong immunomodulatory functions and could treat inflammatory diseases, there is no report on the therapeutic effect of Schistosoma japonicum-produced cystatin (Sj-Cys) on sepsis-induced cardiac dysfunction.

METHODS

A model of sepsis-induced myocardial injury was established by cecal ligation and puncture (CLP) in mice. Upon CLP operation, each mouse was intraperitoneally treated with 10 µg of recombinant Sj-Cys (rSj-Cys). Twelve hours after CLP, the systolic and diastolic functions of the left ventricular were examined by echocardiography. The levels of myoglobin (Mb), cardiac troponin I (cTnI), N-terminal pro-Brain Natriuretic peptide (NT-proBNP) in sera, and the activity of myeloperoxidase (MPO) in cardiac tissues were examined as biomarkers for heart injury. The heart tissue was collected for checking pathological changes, macrophages and pro-inflammatory cytokine levels. To address the signaling pathway involved in the anti-inflammatory effects of rSj-Cys, myeloid differentiation factor 88 (MyD88) was determined in heart tissue of mice with sepsis and LPS-stimulated H9C2 cardiomyocytes. In addition, the therapeutic effects of rSj-Cys on LPS-induced cardiomyocyte apoptosis were also detected. The levels of M1 biomarker iNOS and M2 biomarker Arg-1 were detected in heart tissue. The pro-inflammatory cytokines TNF-α and IL-6, and regulatory cytokines IL-10 and TGF-β were measured in sera and their mRNA levels in heart tissue of rSj-Cys-treated mice.

RESULTS

After rSj-Cys treatment, the sepsis-induced heart malfunction was largely improved. The inflammation and injury of heart tissue were significantly alleviated, characterized as significantly decreased infiltration of inflammatory cells in cardiac tissues and fiber swelling, reduced levels of Mb, cTnI and NT-proBNP in sera, and MPO activity in heart tissue. The therapeutic efficacy of rSj-Cys is associated with downregulated pro-inflammatory cytokines (TNF-α and IL-6) and upregulated regulatory inflammatory cytokines (IL-10 and TGF-β), possibly through inhibiting the LPS-MyD88 signal pathway.

CONCLUSIONS

RSj-Cys significantly reduced sepsis-induced cardiomyopathy and could be considered as a potential therapeutic agent for the prevention and treatment of sepsis associated cardiac dysfunction.

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.

[Intervention with Schistosoma japonicum cysteine protease inhibitor for treatment of lipopolysaccharide-induced sepsis in mice]

OBJECTIVE

To observe the effect of Schistosoma japonicum cysteine protease inhibitor (rSjCystatin) for treatment of lipopolysaccharide (LPS)-induced sepsis in mice.

METHODS

After a week of adaptive feeding, 54 BALB/c mice were randomly divided into normal control group (group A), sepsis group (group B), and rSjCystatin intervention group (group C). The mice in group A received an intraperitoneal injection of PBS (100 µL), and those in groups B and C were injected with PBS (100 µL) containing LPS (10 mg/kg); the mice in group C were also intraperitoneally injected with 25 µg sjCystatin in 100 µL PBS 30 min after LPS injection. From each group, 10 mice were randomly selected 24 h after PBS or LPS injection for detecting serum levels of TNF-α, IL-6, and IL-10 using ELISA and the levels of ALT, AST, BUN, and Cr using automatic biochemical analyzer; the pathological changes in the liver, lung and kidney were observed with HE staining. The remaining 8 mice in each group were used for observing the changes in the general condition and the 72-h survival.

RESULTS

The 72-h survival rates of the mice was 100% in group A, 0 in group B, and 36% in group C, showing a significant difference among the 3 groups (P<0.05). Compared with those in group A, the mice in group B exhibited obvious liver, lung, and renal pathologies with increased levels of ALT, AST, BUN, Cr, IL-6, and TNF-α (P<0.05). Treatment with sjCystatin significantly lessened LPS-induced organ pathologies, lowered the levels of liver and renal functional indexes and the pro-inflammatory cytokines, and increased the serum level of IL-10 in the mice (P<0.05).

CONCLUSION

SjCystatin can produce a significant therapeutic effect on sepsis induced by LPS in mice.

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.

Functional characterization of single-domain cystatin-like cysteine proteinase inhibitors expressed by the trematode Fasciola hepatica

Cystatins are small, phylogenetically conserved proteins that are tight-binding inhibitors of cysteine proteinases. The liver fluke Fasciola hepatica uses a diverse set of cysteine proteinases of the papain superfamily for host invasion, immune evasion and nutrition, but little is known about the regulation of these enzymes. The aim of this work is to characterize the cystatin repertoire of F. hepatica. For this purpose, we first surveyed the available sequence databases, identifying three different F. hepatica single-domain cystatins. In agreement with the in silico predictions, at least three small proteins with cysteine proteinase binding activity were identified. Phylogenetic analyses showed that the three cystatins (named FhStf-1, -2 and -3) are members of the I25A subfamily (stefins). Whereas FhStf-1 grouped with classical stefins, FhStf-2 and 3 fell in a divergent stefin subgroup unusually featuring signal peptides. Recombinant rFhStf-1, -2 and -3 had potent inhibitory activity against F. hepatica cathepsin L cysteine proteinases but differed in their capacity to inhibit mammalian cathepsin B, L and C. FhStf-1 was localized in the F. hepatica reproductive organs (testes and ovary), and at the surface lamella of the adult gut, where it may regulate cysteine proteinases related with reproduction and digestion, respectively. FhStf-1 was also detected among F. hepatica excretion-secretion (E/S) products of adult flukes. This suggests that it is secreted by non-classical secretory pathway and that it may interact with host lysosomal cysteine proteinases.

Therapeutic effect of Schistosoma japonicum cystatin on bacterial sepsis in mice

BACKGROUND

Sepsis is a life-threatening complication of an infection and remains one of the leading causes of mortality in surgical patients. Bacteremia induces excessive inflammatory responses that result in multiple organ damage. Chronic helminth infection and helminth-derived materials have been found to immunomodulate host immune system to reduce inflammation against some allergic or inflammatory diseases. Schistosoma japonicum cystatin (Sj-Cys) is a cysteine protease inhibitor that induces regulatory T-cells and a potential immunomodulatory. The effect of Sj-Cys on reducing sepsis inflammation and mortality was investigated.

METHODS

Sepsis was induced in BALB/c mice using cecal ligation and puncture (CLP), followed by intraperitoneal injection of different doses (10, 25 or 50 μg) of recombinant Sj-Cys (rSj-Cys). The therapeutic effect of rSj-Cys on sepsis was evaluated by observing the survival rates of mice for 96 h after CLP and the pathological injury of liver, kidney and lung by measuring the levels of alanine transaminase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN) and creatinine (Cr) in sera and the tissue sections pathology, and the expression of MyD88 in liver, kidney and lung tissues. The immunological mechanism was investigated by examining pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) and IL-10 and TGF-β1 in mice sera and in culture of macrophages stimulated by lipopolysaccharides (LPS).

RESULTS

rSj-Cys treatment provided significant therapeutic effects on CLP-induced sepsis in mice demonstrated with increased survival rates, alleviated overall disease severity and tissue injury of liver, kidney and lung. The rSj-Cys conferred therapeutic efficacy was associated with upregualted IL-10 and TGF-β1 cytokines and reduced pro-inflammatory cytokines TNF-α, IL-6, IL-1β. MyD88 expression in liver, kidney and lung tissues of rSj-Cys-treated mice was reduced. In vitro assay with macrophages also showed that rSj-Cys inhibited the release of pro-inflammatory cytokines and mediator nitric oxide (NO) after being stimulated by lipopolysaccharide (LPS).

CONCLUSIONS

The results suggest the anti-inflammatory potential of rSj-Cys as a promising therapeutic agent on sepsis. The immunological mechanism underlying its therapeutic effect may involve the downregulation of pro-inflammatory cytokines and upregulation of IL-10 and TGF-β1 cytokines possibly via downregulation of the TLR adaptor-transducer MyD88 pathway. The findings suggest rSj-Cys is a potential therapeutic agent for sepsis and other inflammatory diseases.

(5R)-5-hydroxytriptolide (LLDT-8) prevents collagen-induced arthritis through OPG/RANK/RANKL signaling in a rat model of rheumatoid arthritis

(5R)-5-hydroxytriptolide (LLDT-8) extracts from Tripterygium have anti-inflammatory, antineoplastic and immunity adjustment functions. The present study used a collagen-induced arthritis (CIA) model to evaluate whether LLDT-8 prevents collagen-induced arthritis, and investigated the signaling underlying this. Male Sprague-Dawley rats were induced to generate CIA, mimicking rheumatoid arthritis (RA). The presence of arthritis was determined using RA progression scores. The inflammatory cytokines interleukin (IL)-1β, IL-6 and nuclear factor-κB were detected using enzyme-linked immunosorbent assay kits. Induced nitric oxide synthase (iNOS) and matrix metalloprotease (MMP)-13 protein expression were measured using western blot analysis. Lastly, reverse transcription-quantitative polymerase chain reaction was used to evaluate osteoprotegerin (OPG) and receptor activator of nuclear factor κB (RANK) gene expression. LLDT-8 improved RA progression scores and reduced the incidence and severity of CIA. Furthermore, LLDT-8 administration inhibited collagen-induced inflammation and iNOS protein expression in arthritic rats. The current data indicated that MMP-13 production was suppressed and OPG/RANKL expression was increased by LLDT-8 treatment in the arthritic rat. The present results suggest that LLDT-8 attenuates CIA through OPG/RANK/RANK ligand signaling in a rat model of RA.