Effect of recombinant Trichinella spiralis cysteine proteinase inhibitor on TNBS-induced experimental inflammatory bowel disease in mice

The prophylactic and therapeutic impact of Trichinella spiralis larvae excretory secretory antigens- loaded Ca-BTC metal organic frameworks on induced murine colitis

Background: Inflammatory bowel disease is an autoimmune disease that affects the gut. T. spiralis larvae (E/S Ags) loaded on calcium-benzene-1,3,5-tricarboxylate metal-organic frameworks (Ca-BTC MOFs) were tested to determine whether they might prevent or cure acetic acid-induced murine colitis. Methods: T. spiralis larvae E/S Ags/Ca-BTC MOFs were used in prophylactic and therapeutic groups to either precede or follow the development of murine colitis. On the seventh day after colitis, mice were slaughtered. The effect of our target antigens on the progress of the colitis was evaluated using a variety of measures, including survival rate, disease activity index, colon weight/bodyweight, colon weight/length) ratios, and ratings for macroscopic and microscopic colon damage. The levels of inflammatory cytokines (interferon-γ and interleukin-4), oxidative stress marker malondialdehyde, and glutathione peroxidase in serum samples were evaluated. Foxp3 T-reg expression was carried out in colonic and splenic tissues. Results: T. spiralis larvae E/S Ags/Ca-BTC MOFs were the most effective in alleviating severe inflammation in murine colitis. The survival rate, disease activity index score, colon weight/length and colon weight/bodyweight ratios, and gross and microscopic colon damage scores have all considerably improved. A large decrease in proinflammatory cytokine (interferon-γ) and oxidative stress marker (malondialdehyde) expression and a significant increase in interleukin-4 and glutathione peroxidase expression were obtained. The expression of Foxp3+ Treg cells was elevated in colonic and splenic tissues. Conclusion: T. spiralis larvae E/S Ags/Ca-BTC MOFs had the highest anti-inflammatory, antioxidant, and cytoprotective capabilities against murine colitis and might be used to develop new preventative and treatment strategies.

Galectin from Trichinella spiralis alleviates DSS-induced colitis in mice by regulating the intestinal microbiota

According to numerous reports, Trichinella spiralis (T. spiralis) and its antigens can reduce intestinal inflammation by modulating regulatory immunological responses in the host to maintain immune homeostasis. Galectin has been identified as a protein that is produced by T. spiralis, and its characterization revealed this protein has possible immune regulatory activity. However, whether recombinant T. spiralis galectin (rTs-gal) can cure dextran sulfate sodium (DSS)-induced colitis remains unknown. Here, the ability of rTs-gal to ameliorate experimental colitis in mice with inflammatory bowel disease (IBD) as well as the potential underlying mechanism were investigated. The disease activity index (DAI), colon shortening, inflammatory cell infiltration, and histological damage were used as indicators to monitor clinical symptoms of colitis. The results revealed that the administration of rTs-gal ameliorated these symptoms. According to Western blotting and ELISA results, rTs-gal may suppress the excessive inflammatory response-mediated induction of TLR4, MyD88, and NF-κB expression in the colon. Mice with colitis exhibit disruptions in the gut flora, including an increase in gram-negative bacteria, which in turn can result in increased lipopolysaccharide (LPS) production. However, injection of rTs-gal may inhibit changes in the gut microbiota, for example, by reducing the prevalence of Helicobacter and Bacteroides, which produce LPS. The findings of the present study revealed that rTs-gal may inhibit signalling pathways that involve enteric bacteria-derived LPS, TLR4, and NF-κB in mice with DSS-induced colitis and attenuate DSS-induced colitis in animals by modulating the gut microbiota. These findings shed additional light on the immunological processes underlying the beneficial effects of helminth-derived proteins in medicine.

Amelioration of ovalbumin-induced lung inflammation in a mouse model by Trichinella spiralis novel cystatin

Background and Aims

Asthma, a chronic disease affecting humans and animals, has recently become increasingly prevalent and steadily widespread. The alternative treatment of asthma using helminth infections or helminth-derived immunomodulatory molecules (IMs) has been evaluated and demonstrated significant amelioration of disease severity index in vitro and in vivo. Trichinella spiralis, a parasitic nematode and its IMs, elicits a potential to relieve asthma and other immune-related disorders. In this study, we investigated the immunomodulatory function of recombinant T. spiralis novel cystatin (rTsCstN) in ameliorating acute inflammatory asthma disorders in a murine model.

Materials and Methods

Female BALB/c mice were sensitized using intraperitoneal injection of ovalbumin (OVA)/alum and subsequently challenged with intranasal administration of OVA alone or OVA + rTsCstN for 3 consecutive days, producing OVA-induced allergic asthma models. To evaluate the therapeutic efficacy of rTsCstN, the inflammatory cells and cytokines in bronchoalveolar lavage fluid (BALF) and OVA-specific immunoglobulin E levels in serum were assessed. Histological alterations in the lung tissues were determined by hematoxylin and eosin (H&E) staining and eventually scored for the extent of inflammatory cell infiltration.

Results

The asthmatic mouse models challenged with OVA + rTsCstN demonstrated a significant reduction of eosinophils (p < 0.01), macrophages (p < 0.05), and cytokines tumor necrosis factor-α (p < 0.05) and interferon (IFN)-γ (p < 0.05) in BALF when compared with the mice challenged with OVA alone. However, the levels of interleukin (IL)-4 and IL-10 remained unchanged. Histological examination revealed that mice administered OVA + rTsCstN were less likely to have inflammatory cell infiltration in their perivascular and peribronchial lung tissues than those administered OVA alone.

Conclusion

Recombinant T. spiralis novel cystatin demonstrated immunomodulatory effects to reduce severe pathogenic alterations in asthma mouse models, encouraging a viable alternative treatment for asthma and other immunoregulatory disorders in humans and animals in the future.

Excretory/secretory products from Trichinella spiralis adult worms ameliorate myocardial infarction by inducing M2 macrophage polarization in a mouse model

BACKGROUND

Ischemia-induced inflammatory response is the main pathological mechanism of myocardial infarction (MI)-caused heart tissue injury. It has been known that helminths and worm-derived proteins are capable of modulating host immune response to suppress excessive inflammation as a survival strategy. Excretory/secretory products from Trichinella spiralis adult worms (Ts-AES) have been shown to ameliorate inflammation-related diseases. In this study, Ts-AES were used to treat mice with MI to determine its therapeutic effect on reducing MI-induced heart inflammation and the immunological mechanism involved in the treatment.

METHODS

The MI model was established by the ligation of the left anterior descending coronary artery, followed by the treatment of Ts-AES by intraperitoneal injection. The therapeutic effect of Ts-AES on MI was evaluated by measuring the heart/body weight ratio, cardiac systolic and diastolic functions, histopathological change in affected heart tissue and observing the 28-day survival rate. The effect of Ts-AES on mouse macrophage polarization was determined by stimulating mouse bone marrow macrophages in vitro with Ts-AES, and the macrophage phenotype was determined by flow cytometry. The protective effect of Ts-AES-regulated macrophage polarization on hypoxic cardiomyocytes was determined by in vitro co-culturing Ts-AES-induced mouse bone marrow macrophages with hypoxic cardiomyocytes and cardiomyocyte apoptosis determined by flow cytometry.

RESULTS

We observed that treatment with Ts-AES significantly improved cardiac function and ventricular remodeling, reduced pathological damage and mortality in mice with MI, associated with decreased pro-inflammatory cytokine levels, increased regulatory cytokine expression and promoted macrophage polarization from M1 to M2 type in MI mice. Ts-AES-induced M2 macrophage polarization also reduced apoptosis of hypoxic cardiomyocytes in vitro.

CONCLUSIONS

Our results demonstrate that Ts-AES ameliorates MI in mice by promoting the polarization of macrophages toward the M2 type. Ts-AES is a potential pharmaceutical agent for the treatment of MI and other inflammation-related diseases.

A target-based discovery from a parasitic helminth as a novel therapeutic approach for autoimmune diseases

BACKGROUND

Regulatory T cells (Tregs) can alleviate the development of autoimmune and inflammatory diseases, thereby proposing their role as a new therapeutic strategy. Parasitic helminths have co-evolved with hosts to generate immunological privilege and immune tolerance through inducing Tregs. Thus, constructing a "Tregs-induction"-based discovery pipeline from parasitic helminth is a promising strategy to control autoimmune and inflammatory diseases.

METHODS

The gel filtration chromatography and reverse-phase high-performance liquid chromatography (RP-HPLC) were used to isolate immunomodulatory components from the egg extracts of Schistosoma japonicum. The extracted peptides were evaluated for their effects on Tregs suppressive functions using flow cytometry, ELISA and T cell suppression assay. Finally, we carried out colitis and psoriasis models to evaluate the function of Tregs induced by helminth-derived peptide in vivo.

FINDINGS

Here, based on target-driven discovery strategy, we successfully identified a small 3 kDa peptide (SjDX5-53) from egg extracts of schistosome, which promoted both human and murine Tregs production. SjDX5-53 presented immunosuppressive function by arresting dendritic cells (DCs) at an immature state and augmenting the proportion and suppressive capacity of Tregs. In mouse models, SjDX5-53 protected mice against autoimmune-related colitis and psoriasis through inducing Tregs and inhibiting inflammatory T-helper (Th) 1 and Th17 responses.

INTERPRETATION

SjDX5-53 exhibited the promising therapeutic effects in alleviating the phenotype of immune-related colitis and psoriasis. This study displayed a screening and validation pipeline of the inducer of Tregs from helminth eggs, highlighting the discovery of new biologics inspired by co-evolution of hosts and their parasites.

FUNDING

This study was supported by the Natural Science Foundation of China (82272368) and Natural Science Foundation of Jiangsu Province (BK20211586).

Inhibition of GSDMD-mediated pyroptosis triggered by Trichinella spiralis intervention contributes to the alleviation of DSS-induced ulcerative colitis in mice

BACKGROUND

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is increasing worldwide. Although there is currently no completely curative treatment, helminthic therapy shows certain therapeutic potential for UC. Many studies have found that Trichinella spiralis (T.s) has a protective effect on UC, but the specific mechanism is still unclear.

METHODS

Balb/c mice drank dextran sulfate sodium (DSS) to induce acute colitis and then were treated with T.s. In vitro experiments, the LPS combination with ATP was used to induce the pyroptosis model, followed by intervention with crude protein from T.s (T.s cp). Additionally, the pyroptosis agonist of NSC or the pyroptosis inhibitor vx-765 was added to intervene to explore the role of pyroptosis in DSS-induced acute colitis. The degree of pyroptosis was evaluated by western blot, qPCR and IHC, etc., in vivo and in vitro.

RESULTS

T.s intervention significantly inhibited NLRP3 inflammasome activation and GSDMD-mediated pyroptosis by downregulating the expression of pyroptosis-related signatures in vitro (cellular inflammatory model) and in vivo (DSS-induced UC mice model). Furthermore, blockade of GSDMD-mediated pyroptosis by the caspase-1 inhibitor vx-765 has a similar therapeutic effect on DSS-induced UC mice with T.s intervention, thus indicating that T.s intervention alleviated DSS-induced UC in mice by inhibiting GSDMD-mediated pyroptosis.

CONCLUSION

This study showed that T.s could alleviate the pathological severity UC via GSDMD-mediated pyroptosis, and it provides new insight into the mechanistic study and application of helminths in treating colitis.

Intervention effects of Trichinella spiralis excretory-secretory antigens on allergic asthma in mice

Allergic asthma is a chronic, heterogeneous and inflammatory respiratory disease, and there are few medicines at present. An increasing number of studies indicate that Trichinella spiralis (T. spiralis) and its excretory-secretory (ES) antigens are inflammatory modulator. Therefore, this study focused on the effects of T. spiralis ES antigens on allergic asthma. Asthma model was established by sensitizing mice with ovalbumin antigen (OVA) and aluminum hydroxide (Al[OH]₃), the asthmatic mice were interfered using T. spiralis 43 kDa protein (Ts43), T. spiralis 49 kDa protein (Ts49), and T. spiralis 53 kDa protein (Ts53), the important components of ES antigens, to establish ES antigens intervention models. Then, asthma symptom changes, weight changes, and lung inflammation of mice were evaluated. The results showed that ES antigens could relieve symptoms, weight loss, and lung inflammation caused by asthma in the mice, and the effect of combined intervention of Ts43, Ts49, and Ts53 was better. Finally, the effects of ES antigens on type 1 helper T (Th1) and type 2 helper T (Th2) immune responses, and the differentiation direction of T lymphocytes in mice were discussed by detecting Th1 and Th2 cell-related factors and the ratio of CD₄⁺/CD₈⁺ T cells. The results suggested that the ratio of CD₄⁺/CD₈⁺ T cells decreased and the ratio of Th1/Th2 cells increased. In conclusion, this study indicated that T. spiralis ES antigens could mitigate allergic asthma in the mice by changing the differentiation direction of CD₄⁺ and CD₈⁺ T cells and regulating the imbalance of Th1/Th2 cells ratio.

Trichinella spiralis infection ameliorates the severity of Citrobacter rodentium-induced experimental colitis in mice

Trichinellosis is a food-borne zoonotic parasitic disease that causes serious harm to human health and the pig breeding industry. However, there are reports that Trichinella spiralis (T. spiralis) infection can treat autoimmune diseases, including enteritis and experimental autoimmune encephalitis (EAE). However, research on the mechanism of T. spiralis infection in infectious enteritis has not been fully elucidated. Therefore, this experiment used Citrobacter rodentium (C. rodentium) to induce colitis in mouse models and explored its underlying mechanisms. In this experiment, a total of 72 C57BL/6 mice were randomly divided into four groups. Experimental mice in the TS and TS + CR groups were orally inoculated with individual T. spiralis larvae. At 21 days postinfection (dpi) with T. spiralis, experimental animals in the CR and TS + CR groups were inoculated by orogastric gavage with C. rodentium. The control group received PBS only. The results indicated that the weight loss and macroscopic and microscopic colon damage of mice in the TS + CR group were significantly decreased compared with those observed in the CR group. The results of flow cytometry showed that the expression levels of IL-4, IL-10 and CD4+CD25+Foxp3+ Tregs were increased (P < 0.05), while the expression levels of IFN-γ, IL-12 and IL-17 were decreased in the spleens and MLNs of the TS + CR experimental mice compared with the colitis model mice. ELISA results revealed that the TS + CR group not only elicited a strong IgG1 response (P < 0.01) but also a low level of IgG2a response (P < 0.05) relative to the CR group. The above results demonstrated that prior exposure of mice to T. spiralis infection ameliorated the severity of C. rodentium-induced infectious colitis.

Potential of human helminth therapy for resolution of inflammatory bowel disease: The future ahead

Inflammatory bowel disease (IBD) is associated with a dysregulated mucosal immune response in the gastrointestinal tract. The number of patients with IBD has increased worldwide, especially in highly industrialized western societies. The population of patients with IBD in North America is forecasted to reach about four million by 2030; meanwhile, there is no definitive therapy for IBD. Current anti-inflammatory, immunosuppressive, or biological treatment may induce and maintain remission, but not all patients respond to these treatments. Recent studies explored parasitic helminths as a novel modality of therapy due to their potent immunoregulatory properties in humans. Research using IBD animal models infected with a helminth or administered helminth-derived products such as excretory-secretory products has been promising, and helminth-microbiota interactions exert their anti-inflammatory effects by modulating the host immunity. Recent studies also indicate that evidence that helminth-derived metabolites may play a role in anticolitic effects. Thus, the helminth shows a potential benefit for treatment against IBD. Here we review the current feasibility of "helminth therapy" from the laboratory for application in IBD management.

Harnessing immunomodulatory mechanisms of Trichinella spiralis to design novel nanomedical approaches for restoring self-tolerance in autoimmunity

The rapid increase in the prevalence of autoimmune diseases in recent decades, especially in developed countries, coincided with improved living conditions and healthcare. Part of this increase could be ascribed to the lack of exposure to infectious agents like helminths that co-evolved with us and display potent immune regulatory actions. In this review we discussed many investigations, including our own, showing that Trichinella spiralis via its excretory-secretory products attenuate Th1/Th17 immunopathological response in autoimmunity and potentiate the protective Th2 and or regulatory T cell response, acting as an effective induction of tolerogenic dendritic cells (DCs), and probably mimicking the autoantigen in some diseases. A recent discovery of T. spiralis extracellular vesicles (TsEVs) suggested that inducing a complex regulation of the immune response requires simultaneous delivery of different signals in nano-sized packages. Indeed, different artificial nanomedical approaches discussed here suggested that co-delivery of multiple signals via nanoparticles is the most promising strategy for the treatment of autoimmune diseases. Although a long way is ahead of us before we could completely replicate natural nano-delivery systems which are both safe and potent in restoring self-tolerance, a clear path is being opened from a careful examination of parasite-host interactions.

Gut Serpinome: Emerging Evidence in IBD

Inflammatory bowel diseases (IBD) are incurable disorders whose prevalence and global socioeconomic impact are increasing. While the role of host genetics and immunity is well documented, that of gut microbiota dysbiosis is increasingly being studied. However, the molecular basis of the dialogue between the gut microbiota and the host remains poorly understood. Increased activity of serine proteases is demonstrated in IBD patients and may contribute to the onset and the maintenance of the disease. The intestinal proteolytic balance is the result of an equilibrium between the proteases and their corresponding inhibitors. Interestingly, the serine protease inhibitors (serpins) encoded by the host are well reported; in contrast, those from the gut microbiota remain poorly studied. In this review, we provide a concise analysis of the roles of serine protease in IBD physiopathology and we focus on the serpins from the gut microbiota (gut serpinome) and their relevance as a promising therapeutic approach.

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.

Therapeutic Efficacy of Excretory-Secretory Products of Trichinella spiralis Adult Worms on Sepsis-Induced Acute Lung Injury in a Mouse Model

Acute lung injury (ALI) is a common complication of systemic inflammation or sepsis with high morbidity and mortality. Although many studies have confirmed that helminth-derived proteins had strong immunomodulatory functions and could be used to treat inflammatory diseases, there is no report on the therapeutic effect of excretory-secretory products of Trichinella spiralis adult worms (Ts-AES) on sepsis-induced ALI. In this study, the therapeutic efficacy of Ts-AES on sepsis-induced ALI and the underlying immunological mechanism and the signaling pathway were investigated. The results indicated that after being treated with Ts-AES, the survival rate of mice with CLP-induced sepsis was significantly increased to 50% for 72 hours after CLP surgery compared to PBS control group with all mice died. The sepsis-induced ALI was largely mitigated characterized by reduced inflammation cell infiltration and pathological changes in lung tissue, with decreased lung injury scores and lung wet/dry weight ratio. The therapeutic efficacy of Ts-AES is associated with stimulated Tregs response with increased regulatory cytokines IL-10 and TGF-β and downregulated pro-inflammatory cytokines (TNF-α, IL-6, IL-1β). The expression of HMGB1, TLR2 and MyD88 in lung tissue was inhibited after treatment of Ts-AES. Our results demonstrated that Ts-AES play an important role in immunomodulation and confer a therapeutic effect on sepsis-induced ALI through inhibiting pro-inflammatory cytokines. The activation of Tregs and increased level of regulatory cytokines IL-10 and TGF-β are possibly involved in the immunomodulatory functions of Ts-AES through HMGB1/TLR2/MyD88 signal pathway. The findings suggest Ts-AES is a potential therapeutic agent for prevention and treatment of sepsis-induced ALI and other inflammatory diseases.

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.

The Regulation of Intestinal Inflammation and Cancer Development by Type 2 Immune Responses

The gut is among the most complex organs of the human body. It has to exert several functions including food and water absorption while setting up an efficient barrier to the outside world. Dysfunction of the gut can be life-threatening. Diseases of the gastrointestinal tract such as inflammatory bowel disease, infections, or colorectal cancer, therefore, pose substantial challenges to clinical care. The intestinal epithelium plays an important role in intestinal disease development. It not only establishes an important barrier against the gut lumen but also constantly signals information about the gut lumen and its composition to immune cells in the bowel wall. Such signaling across the epithelial barrier also occurs in the other direction. Intestinal epithelial cells respond to cytokines and other mediators of immune cells in the lamina propria and shape the microbial community within the gut by producing various antimicrobial peptides. Thus, the epithelium can be considered as an interpreter between the microbiota and the mucosal immune system, safeguarding and moderating communication to the benefit of the host. Type 2 immune responses play important roles in immune-epithelial communication. They contribute to gut tissue homeostasis and protect the host against infections with helminths. However, they are also involved in pathogenic pathways in inflammatory bowel disease and colorectal cancer. The current review provides an overview of current concepts regarding type 2 immune responses in intestinal physiology and pathophysiology.

Effect of recombinant serine protease from newborn larval stage of Trichinella spiralis on 2,4,6-trinitrobenzene sulfonic acid-induced experimental colitis in mice

Inflammatory bowel disease (IBD) is a complex immune-mediated disease of gastrointestinal tract that is mainly driven by Th1/Th17 immune response. "Helminth therapy" has emerged, and helminth-derived immunoregulatory molecules are being used as safe and new therapeutic antigens for IBD. Recombinant serine protease (SP) from newborn Trichinella spiralis (T. spiralis) larvae (NBL) was expressed and purified. BALB/c mice were immunized with NBL-SP at 100 µg three times at an interval of 5 days. Experimental colitis was induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS) administration. The disease activity index (DAI) and macroscopic and microscopic scores of the colon were assessed to identify the effect of NBL-SP on experimental colitis. Cytokine production in the serum was analysed by meso scale discovery (MSD). Cytokine production in the colon was detected by ELISA. CD4⁺T cell differentiation was measured by flow cytometry. NBL-SP alleviated TNBS-induced colitis in mice. The DAI, macroscopic and microscopic scores and colon length all showed a positive intervention effect of NBL-SP on experimental colitis. NBL-SP can weaken the increase in IFN-γ, TNF-α and IL-17 production as well as CD4⁺ IFN-γ⁺T cell and CD4⁺IL-17⁺T cell populations induced by colitis. Furthermore, the levels of Th2-related cytokines (IL-4, IL-5) and regulatory cytokines (IL-10, TGF-β) were elevated meanwhile the ratio of regulatory T cells (Tregs) and CD4⁺ IL-4 ⁺ T cells were increased by NBL-SP. NBL-SP of T. spiralis had a potential protective effect against IBD. NBL-SP skewed the Th1 and Th17-mediated response towards the Th2 and Treg response.

Trichinella spiralis: inflammation modulator

The hygiene hypothesis posits that the decreased incidence of parasitic infection in developed countries may underlie an increased prevalence of allergic and autoimmune diseases in these countries. As unique inflammation modulator of intracellular parasitism, Trichinella spiralis, or its excretory-secretory (ES) product, shows improved responses to allergies, autoimmune diseases, inflammatory bowel disease, type 1 diabetes, rheumatic arthritis and autoimmune encephalomyelitis by exerting immunomodulatory effects on both innate and adaptive immune cells in animal models. Research has shown that T. spiralis differs from other helminths in manipulation of the host immune response not only by well-known characteristics of its life cycle, but also by its inflammation modulation pathway. How the parasite achieves inflammation modulation has not been fully elucidated yet. This review will generalize the mechanism and focuses on ES immunomodulatory molecules of T. spiralis that may be important for developing new therapeutics for inflammatory disorders.

Effect of recombinant serine protease from adult stage of Trichinella spiralis on TNBS-induced experimental colitis in mice

Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD), is a chronic autoimmune disease. At present, worms and their products has been shown to have protective effects on immune-mediated diseases. Therefore, we aimed to investigate the effect of the recombination Trichinella spiralis (T. spiralis, Ts) adult serine protease-like protein rTs-ADSp-7 on a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD mouse model. Colitis was induced by intrarectal administration of a TNBS solution. The disease activity index (DAI), which included weight loss, diarrhoea, and bloody stool, was measured. Colon segments were stained with haematoxylin and eosin (H.E.) for histopathological score. Cytokine release in the serum was analysed by meso scale discovery (MSD). Cytokine release in the colon was detected by ELISA. Splenocytes were separated, and the cytokine profiles of Th1 (IFN-γ), Th2 (IL-4), Th17 (IL-17A) and Treg cells were analysed by flow cytometry. Our result showed that rTs-ADSp-7 reduced the clinical disease activity of TNBS-induced colitis in mice. In addition, we found that rTs-ADSp-7 reduced the production of Th1- and Th17-related cytokines while upregulating the expression of Th2- and Treg-related cytokines in TNBS-induced colitis mice. rTs-ADSp-7 also increased the population of Th2 and Treg cells in TNBS-induced colitis mice. rTs-ADSp-7 alleviated the severity of TNBS-induced colitis while balancing the CD4⁺ T cell immune response. rTs-ADSp-7 has therapeutic potential for colitis treatment and can be used as a helminth-derived protein therapy for CD or other Th1 immunity-mediated diseases.

Effect of Trichinella spp. or derived antigens on chemically induced inflammatory bowel disease (IBD) in mouse models: A systematic review and meta-analysis

OBJECTIVE

Trichinella or derived antigens have been suggested to be potential therapeutic agents for inflammatory bowel disease (IBD). We aimed to conduct a systematic review and meta-analysis of the available literature to estimate the effect of Trichinella or derived antigens on chemically induced IBD.

METHODS

Studies were identified by searching the Cochrane Central Register of Controlled Trials, PubMed, Scopus, Web of Science, and Science Direct from inception to February 2020. We included articles written in English that investigated the effect of Trichinella infection and/or derived products in mouse models of IBD. Studies were pooled, and the combined standard mean difference (SMD) and 95% confidence interval (CI) were calculated using a random-effect or fixed-effect model.

RESULTS

Thirteen studies were eventually included in the meta-analysis. The results indicated significant differences in the disease activity index (DAI), myeloperoxidase (MPO) activity, macroscopic inflammation score, and microscopic inflammation score between the experimental group and the control group. The anti-inflammatory cytokines interleukin (IL)-4, transforming growth factor-beta (TGF-β), IL-10 and IL-13 were significantly increased in the experimental group compared with the control group, whereas the levels of the proinflammatory cytokines interferon (IFN)-γ, IL-6, TNF-α, and IL-17 were significantly decreased. The percentage of regulatory T (Treg) cells was also significantly increased, while the level of the M1 phenotypic macrophage marker iNOS was significantly decreased and the expression of the M2 phenotypic macrophage marker Arg-1 was significantly increased.

CONCLUSION

Trichinella infection or derived antigens is effective for the alleviation of IBD in mouse models.

Inflammatory bowel diseases, the hygiene hypothesis and the other side of the microbiota: Parasites and fungi

This review tackles the concept of the evolutionary mismatch, in relation with the reduction of the prevalence of the so-called "dirty old friends". These formed the variegated community of parasites and microorganisms, either prokaryotic or eukaryotic, that, over long evolutionary times, co-evolved with humans and their ancestors, inhabiting their digestive tracts, and other body districts. This community of microbial symbionts and metazoan parasites is thought to have evolved a complex network of inter-independence with the host, in particular in relation with their immune stimulating capacity, and with the consequent adaptation of the host immune response to this chronic stimulation. Strictly related to this evolutionary mismatch, the hygiene hypothesis, proposed by David Strachan in 1989, foresees that the increase in the incidence of inflammatory and autoimmune disorders during the twentieth century has been caused by the reduced exposure to parasites and microorganisms, especially in industrialized countries. Among these pathologies, inflammatory bowel diseases (IBDs) occupy a prominent role. From these premises, this review summarizes current knowledge on how variations in the composition of the gut bacterial microbiota, as well as its interactions with fungal communities, influence the overall immune balance, favouring or counteracting gut inflammation in IBDs. Additionally, the effect of worm parasites, either directly on the immune balance, or indirectly, through the modulation of bacterial and fungal microbiota, will be addressed. Finally, we will review a series of studies related to the use of molecules derived from parasitic worms and fungi, which hold the potential to be developed as postbiotics for the treatment of IBDs.

Isolation and Functions of Extracellular Vesicles Derived from Parasites: The Promise of a New Era in Immunotherapy, Vaccination, and Diagnosis

Experimental and epidemiological evidence shows that parasites, particularly helminths, play a central role in balancing the host immunity. It was demonstrated that parasites can modulate immune responses via their excretory/secretory (ES) and some specific proteins. Extracellular vesicles (EVs) are nano-scale particles that are released from eukaryotic and prokaryotic cells. EVs in parasitological studies have been mostly employed for immunotherapy of autoimmune diseases, vaccination, and diagnosis. EVs can carry virulence factors and play a central role in the development of parasites in host cells. These molecules can manipulate the immune responses through transcriptional changes. Moreover, EVs derived from helminths modulate the immune system via provoking anti-inflammatory cytokines. On the other hand, EVs from parasite protozoa can induce efficient immunity, that makes them useful for probable next-generation vaccines. In addition, it seems that EVs from parasites may provide new diagnostic approaches for parasitic infections. In the current study, we reviewed isolation methods, functions, and applications of parasite's EVs in immunotherapy, vaccination, and diagnosis.

Effect of T. spiralis Serine protease inhibitors on TNBS-induced experimental colitis mediated by Macrophages

Inflammatory bowel disease (IBD) is an autoimmune disease with increasing incidence rate, and divided into ulcerative colitis (UC) and Crohn’s disease (CD). And more and more experimental evidence supports that immune disorder is important in the pathogenesis of IBD. Our previous experiments have confirmed that TsKaSPI and TsAdSPI recombinant proteins could relieve TNBS (2,4,6-Trinitrobenzenesulfonic acid solution)-induced colitis. Therefore, we speculate that macrophages play a certain role in the process of recombinant protein relieving colitis. In this experiment, 96 male BALB/c mice aged 6–8 weeks were randomly divided into two groups: the prevention group and the therapy group. Changes of the ratio of M1/M2 phenotypic macrophages in spleens and MLNs, key factors in the IL-33/ST2 and IL-6/JAK2/STAT3 signaling pathway were detected. The purpose is to analyze the specific role played by macrophages and their secreted cytokines in the immunomodulation of colitis by Trichinella spiralis (T. spiralis) Serine protease inhibitors. The results showed that the percentage of M1 phenotypic macrophages was decreased and M2 phenotypic macrophages was increased in the TsKaSPI + TNBS, TsAdSPI + TNBS group compared with the PBS + TNBS group in the prevention group. Meanwhile, the expression of IL-33 and ST2 were significantly decreased. The key factors of IL-6/JAK2/STAT3 signaling pathway were all significantly increased. In addition, in the therapy group, we found similar results. This experiment demonstrated that macrophages have a certain impact during this process of recombinant protein relieving mouse CD model.

Effects of Deoxyschisandrin on Visceral Sensitivity of Mice with Inflammatory Bowel Disease

The aims of this study were to build an IBD mouse model and further to observe the effects of deoxyschisandrin on IBD and visceral sensitivity and to evaluate the relevance of brain-derived neurotrophic factor (BDNF) to intestinal hypersensitivity of IBD mice. The results showed that deoxyschisandrin could depress the contraction of isolated smooth muscle, modulate gastrointestinal function, and efficiently decrease the disease activity index (DAI) of IBD mice, which proved that deoxyschisandrin had antidiarrheal effects on the animals. In the colorectal distention (CRD) experiment, visceral sensibility was increased in the model group. However, abdominal withdrawal reflex (AWR) scores were decreased after deoxyschisandrin intervention, indicating that deoxyschisandrin could reduce the visceral hypersensitivity of IBD mice. Both IHC observation and western blotting analysis showed that BDNF protein expression increased evidently in colon of IBD mice. After the intervention of deoxyschisandrin, colon mucosa BDNF protein expression in IBD mice decreased, indicating that deoxyschisandrin could decrease mouse intestinal sensitivity by reducing colon mucosa BDNF expression. In conclusion, deoxyschisandrin possessed antidiarrheal effects and visceral hypersensitivity inhibitory effects in the mice with IBD induced by TNBS, which was related to the reduction in BDNF expression in the colon.

Th2 signals are not essential for the anti-arthritic effects of Trichinella spiralis in mice

AIMS

Many parasitic helminths are known to alter host immune responses and consequently affect the progression of autoimmune and allergic diseases. The parasitic nematode Trichinella sp has been reported to suppress several experimental diseases in rodents, including experimental autoimmune encephalomyelitis, type 1 diabetes, colitis, airway inflammation and autoimmune arthritis. We tried to clarify requirement of Th2 cytokines in the anti-arthritic effects of Trichinella spiralis (Ts) against collagen-induced arthritis (CIA).

METHODS AND RESULTS

We infected Ts and then induced CIA in STAT6KO DBA/1 mice, comparing the disease progression with that in wild-type (WT) DBA/1 mice, Ts significantly mitigated arthritis in WT mice, in addition to the impairment of anti-type II collagen (IIC) IgG production in a subclass-independent manner. The genetic absence of STAT6 in the mice did not abrogate the anti-arthritic effects of Ts. Alteration of splenic cytokines was not related to the anti-arthritic effects of the parasite. Moreover, lack of IL-10 did not abrogate the anti-arthritic effects of Ts.

CONCLUSION

Our results suggest that the anti-arthritic effects of Ts do not require host Th2 signals.

Exosomes Derived From M2b Macrophages Attenuate DSS-Induced Colitis

Macrophages are commonly classified as M1 macrophages or M2 macrophages. The M2 macrophages are further sub-categorized into M2a, M2b, M2c, and M2d subtypes. The M2a, M2b, and M2c subtypes play roles in anti-inflammatory activity, tissue remodeling, type 2 T helper cell (Th2) activation, and immunoregulation. Previous studies have shown that macrophage exosomes can affect some disease processes. Exosomes are 30-150-nm lipid bilayer membrane vesicles derived from most living cells, with important biological functions. The role of exosomes in preventing the development of autoimmune diseases, including inflammatory bowel disease (IBD), has evoked increasing interest. Here, we analyze the roles of exosomes derived from M2a, M2b, and M2c macrophage phenotypes in dextran sulfate sodium (DSS)-induced colitis. Exosomes were isolated from the supernatant of different types of macrophages and identified via transmission electron microscopy (TEM), western blotting, and NanoSight. The results showed that M2b macrophage exosomes significantly attenuated the severity of DSS-induced colitis in mice. The number of regulatory T (Treg) cells in the spleens of mice with colitis and levels of IL-4 both increased following treatment with M2b macrophage exosomes. In addition, key cytokines associated with colitis (IL-1β, IL-6, and IL-17A) were significantly suppressed, following treatment with M2b macrophage exosomes. The M2b macrophage exosomes exerted protective effects on DSS-induced colitis, mainly mediated by the CC chemokine 1 (CCL1)/CCR8 axis. These findings provide a novel approach for the treatment of IBD.