Preventive and therapeutic effects of Trichinella spiralis adult extracts on allergic inflammation in an experimental asthma mouse model

Succinate coenzyme A ligase β-like protein from Trichinella spiralis is a potential therapeutic molecule for allergic asthma

BACKGROUND

For decades, studies have demonstrated the anti-inflammatory potential of proteins secreted by helminths in allergies and asthma. Previous studies have demonstrated the immunomodulatory capabilities of Succinate Coenzyme A ligase beta-like protein (SUCLA-β) derived from Trichinella spiralis, a crucial excretory product of this parasite.

OBJECTIVE

To explore the therapeutic potential of SUCLA-β in alleviating and controlling ovalbumin (OVA)-induced allergic asthma, as well as its influence on host immune modulation.

METHODS

In this research, we utilized the rTs-SUCLA-β protein derived from T. spiralis to investigate its potential in mitigating airway inflammation in a murine model of asthma induced by OVA sensitization/stimulation, both pre- and post-challenge. The treatment's efficacy was assessed by quantifying the extent of inflammation in the lungs.

RESULTS

Treatment with rTs-SUCLA-β demonstrated efficacy in ameliorating OVA-induced airway inflammation, as evidenced by a reduction in eosinophil infiltration, levels of OVA-specific Immunoglobulin E, interferon-γ, interleukin (IL)-9, and IL-17A, along with an elevation in IL-10. The equilibrium between Th17 and Treg cells plays a pivotal role in modulating the abundance of inflammatory cells within the organism, thereby ameliorating inflammation and alleviating symptoms associated with allergic asthma.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data revealed that T. spiralis-derived Ts-SUCLA-β protein may inhibit the allergic airway inflammation by regulating host immune responses.

Anti-CD1d treatment suppresses immunogenic maturation of lung dendritic cells dependent on lung invariant natural killer T cells in asthmatic mice

Our previous findings show that invariant natural killer T (iNKT)cells can promote immunogenic maturation of lung dendritic cells (LDCs) to enhance Th2 cell responses in asthma. It has been accepted that recognition of glycolipid antigens presented by CD1d molecules by the T cell receptors of iNKT cells leads to iNKT cell activation. Therefore, we examine the immunoregulatory influences of anti-CD1d treatment on Th2 cell response and immunogenic maturation of LDCs and subsequently explored whether these influences were dependent on lung iNKT cells in asthmatic mice. We discoveredthat in wild-type mice sensitized and challenged with house dust mite or ovalbumin (OVA), anti-CD1d treatment inhibited Th2 cell response and immunogenic maturation of LDCs. LDCs from asthmatic mice with anti-CD1d treatment had a markedly decreased influence on Th2 cell responses in vivo and in vitro. Furthermore, anti-CD1d treatment reduced the abundance and activation of lung iNKT cells in asthmatic mice. Moreover, in asthmatic iNKT cell-deficient Jα18-/- mice, anti-CD1d treatment did not influence Th2 cell responses and immunogenic maturation of LDCs. Meanwhile, the quantity of CD40L+ iNKT cells in asthmatic mice was significant decreased by anti-CD1d treatment. Finally, the inhibition of anti-CD1d treatment on LDC immunogenic maturation and Th2 cell responses in asthmatic mice was reversed by anti-CD40 treatment. Our data suggest that anti-CD1d treatment can suppress Th2 cell responses through inhibiting immunogenic maturation of LDCs dependent on lung iNKT cells, which couldbe partially related to the downregulation of CD40L expression on lung iNKT cells in asthmatic mice.

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.

Immunologic, genetic, and ecological interplay of factors involved in allergic diseases

An allergic or type I hypersensitivity reaction involves a misdirected immune overreaction to innocuous environmental and dietary antigens called allergens. The genetic predisposition to allergic disease, referred to as atopy, can be expressed as a variety of manifestations-e.g., allergic rhinitis, allergic conjunctivitis, atopic dermatitis, allergic asthma, anaphylaxis. Globally, allergic diseases are one the most common types of chronic conditions. Several factors have been identified to contribute to the pathogenesis and progression of the disease, leading to distinctively variable clinical symptoms. The factors which can attenuate or exacerbate allergic reactions can range from genetic heterozygosity, the prominence of various comorbid infections, and other factors such as pollution, climate, and interactions with other organisms and organism-derived products, and the surrounding environment. As a result, the effective prevention and control of allergies remains to be one of the most prominent public health problems. Therefore, to contextualize the current knowledge about allergic reactions, this review paper attempts to synthesize different aspects of an allergic response to describe its significance in the global health scheme. Specifically, the review shall characterize the biomolecular mechanisms of the pathophysiology of the disease based on underlying disease theories and current findings on ecologic interactions and describe prevention and control strategies being utilized. An integrated perspective that considers the underlying genetic, immunologic, and ecologic aspects of the disease would enable the development of more effective and targeted diagnostic tools and therapeutic strategies for the management and control of allergic diseases.

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 pseudospiralis-secreted 53 kDa protein ameliorates imiquimod-induced psoriasis by inhibiting the IL-23/IL-17 axis in mice

Trichinella infection can experimentally ameliorate many autoimmune diseases. However, the immune mechanism of the amelioration and the identification of corresponding Trichinella-derived molecule(s) are still not fully elucidated. Fifty-three kDa excretory-secretory (ES) protein from Trichinella pseudospiralis (Tpp53) is a molecule like TsP53 reported as a protein exerting immune-inhibitory effect in T. spiralis. In this study, we investigated the immunomodulatory effect of Tpp53 using imiquimod (IMQ)-induced psoriasis-like dermatitis model, which is a mouse model of autoimmune disease with the pathogenic interleukin 17 (IL-17) producing CD4⁺ T cells (Th17) via IL-23/IL17 axis. Administrating the recombinant Tpp53 (rTpp53) mixed with IMQ cream on the skin of mice ameliorated psoriatic lesions, as revealed by the improvement of erythema, scaling, skin thickening, epidermis hyperplasia and parakeratosis, thickening of acanthosis cell layer, epidermal extension of dermis, less infiltration of inflammatory cells, and decreased expression of inflammatory marker. The increased expression of the factors related to the IL-23/IL-17 axis, including IL-17A, IL-6, Il17F and Il23a, in the skins of IMQ-treated mice was inhibited by rTpp53 treatment. Moreover, the expression of activated keratinocyte-produced cytokines, chemokines, and antimicrobial peptides in the skin was also down-regulated in rTpp53-treated IMQ-treated mice. Co-culture of splenocytes with rTpp53 inhibited IL-17A and treatment of macrophages with rTpp53 reduced IL-6 production. Overall, our study revealed that the Trichinella-secreted 53 kDa ES protein could ameliorate IMQ-induced psoriasis by inhibiting the IL-23/IL-17 axis, suggesting that Tpp53 might involve in regulating host Th17 for immune evasion and have an alternative potential for psoriasis therapy.

Coinfection of Clonorchis sinensis and hepatitis B virus: clinical liver indices and interaction in hepatic cell models

BACKGROUND

In China, people infected with hepatitis B virus (HBV) are commonly found in areas with a high prevalence of Clonorchis sinensis, a trematode worm. Published studies have reported that the progression of hepatitis B is affected by coinfection C. sinensis.

METHODS

Clinical data from a total of 72 patients with C. sinensis and HBV (as sole infection or with coinfections) and 29 healthy individuals were analysed. We also incubated the hepatic stellate cell line LX-2 with total proteins from C. sinensis adult worms (CsTPs) and HBV-positive sera. In addition, the human hepatoblastoma cell line HepG2.2.15 was treated with the antiviral drug entecavir (ETV), CsTPs and the anti-C. sinensis drug praziquantel (PZQ).

RESULTS

Our clinical data indicated that the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TB) and hyaluronic acid (HA) were significantly higher in patients with coinfection than in those infected with HBV only. In cell models, compared with the model in which LX-2 cells were incubated with HBV-positive sera (HBV group), transcripts of alpha-smooth muscle actin and types I and III collagen were significantly elevated in the models of LX-2 cells treated with CsTPs and HBV-positive sera (CsTP+HBV group), while the messenger RNA levels of tumour necrosis factor-α, interleukin (IL)-1β and IL-6 in the CsTP+HBV group were clearly lower. The HBV surface antigen and hepatitis B e-antigen levels were higher in the HepG2.2.15 cells treated with ETV and CsTPs than in those in the ETV group and in the cells administered a mixture of ETV, CsTPs and PZQ.

CONCLUSIONS

These results confirmed that C. sinensis and HBV coinfection could aggravate the progression of liver fibrosis. CsTPs might promote chronic inflammation of the liver in individuals with HBV infection, resulting in the development of hepatic fibrosis.

Trichinella-induced immunomodulation: Another tale of helminth success

Trichinella spiralis is a unique parasite in that both the adults and larvae survive in two different intracellular niches in the same host. The immune response, albeit intense, is highly modulated to ensure the survival of both the host and the parasite. It is skewed to T helper 2 and regulatory arms. Diverse cells from both the innate and adaptive compartments of immunity, including dendritic cells, T regulatory cells, and alternatively activated macrophages are thought to mediate such immunomodulation. The parasite has also an outstanding ability to evade the immune system by several elaborate processes. The molecules derived from the parasites including Trichinella, particularly the components of the excretory-secretory products, are being continually identified and explored for the potential of ameliorating the immunopathology in animal models of diverse inflammatory and autoimmune human diseases. Herein we discuss the various aspects of Trichinella-induced immunomodulation with a special reference to the practical implications of the immune system manipulation in alleviating or possibly curing human diseases.

Nematode Orthologs of Macrophage Migration Inhibitory Factor (MIF) as Modulators of the Host Immune Response and Potential Therapeutic Targets

One of the adaptations of nematodes, which allows long-term survival in the host, is the production of proteins with immunomodulatory properties. The parasites secrete numerous homologs of human immune mediators, such as macrophage migration inhibitory factor (MIF), which is a substantial regulator of the inflammatory immune response. Homologs of mammalian MIF have been recognized in many species of nematode parasites, but their role has not been fully understood. The application of molecular biology and genetic engineering methods, including the production of recombinant proteins, has enabled better characterization of their structure and properties. This review provides insight into the current state of knowledge on MIF homologs produced by nematodes, as well as their structure, enzymatic activity, tissue expression pattern, impact on the host immune system, and potential use in the treatment of parasitic, inflammatory, and autoimmune diseases.

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.

Immunoprotective inference of experimental chronic Trichinella spiralis infection on house dust mites induced allergic airway remodeling

Allergic bronchial asthma is characterized by chronic inflammation of the respiratory airways mediated by T-helper 2 (Th2), Th17 and their cytokines. Although most asthmatic patients suffer from allergic airway remodeling (AAR), aggressive anti-allergic treatment failed to reverse it. The hygiene hypothesis illuminated the counter relationship between allergy and helminthic infections. The immune system is modulated by Trichinella spiralis (T. spiralis) infection to maintain homeostasis. Therefore, this work aimed to investigate the impact of chronic T. spiralis infection on induced AAR in C57BL/6 mice sensitized by house dust mites (HDM) allergens. Forty mice were divided into 3 groups: I (10 healthy mice), IΙ (15 HDM sensitized mice), and ΙΙI (15 T. spiralis chronically infected mice and sensitized with HDM allergens). The assessment aimed to evaluate the effects of regulatory CD4+CD25+FOXP3+ cells (Tregs) and their cytokines comparative to hypersensitivity mediated cytokines. Chronic T. spiralis infection effectively prevented the host's AAR. This result was evidenced by upregulated Tregs in blood by flow cytometric analysis and increased interleukin-10 (IL-10) levels in bronchoalveolar lavage (BAL) by Enzyme linked immunosorbent assay (ELISA) as well as improved lung histopathological changes. Also, serum HDM specific immunoglobulin E (IgE), BAL eosinophils, BAL IL-5 levels, and IL-17 gene expression in lung tissues were significantly reduced in T. spiralis chronically infected mice. In conclusion, the immune response in chronic T. spiralis infection could provide a promising mechanistic tool for protection against AAR, which paves the way for innovative preventive measures of other immunological disorders.

Extracellular vesicles of Echinococcus granulosus have therapeutic effects in allergic airway inflammation

BACKGROUND

Previous studies have shown that Echinococcus granulosus cystic fluid can alleviate Th2 allergic airway inflammatory responses by increasing the number of CD4⁺ CD25⁺ Foxp3⁺ T (regulatory T; Treg) cells. Parasite-derived extracellular vesicles (EV) are known to not only promote parasite infection by communicating between parasites but also regulate the inflammatory response by acting as an immunomodulatory agent in the host.

METHODS

To evaluate the effect of EV extracted from the cystic fluid of E. granulosus on allergic airway inflammation, gene expression was investigated after administering EV to mouse lung epithelial cells (MLE-12) following 2 h of pretreatment with Aspergillus proteins. An allergic airway inflammation animal model was used to investigate the regulation of the inflammatory response by EV and induced with ovalbumin.

RESULTS

EV treatment significantly reduced airway resistance and the number of eosinophils and other immune cells in the bronchoalveolar lavage fluid and Th2- and Th17-related cytokine levels. EV pretreatment decreased the number of IL-4⁺ CD4⁺ T cells and increased the number of Treg cells in the lung-draining lymph nodes and spleen.

CONCLUSIONS

Echinococcus granulosus cystic fluid derived EV ameliorated Th2 allergic airway inflammatory through Treg cells, similar to whole cystic fluid treatment. Thus, EV may be important immunomodulatory molecules in cystic fluid.

Therapeutic efficacy of mebendazole and artemisinin in different phases of trichinellosis: a comparative experimental study

The present work aimed at studying the efficacy of mebendazole (MBZ) compared to artemisinin (ART) for the treatment of trichinellosis at various phases of infection. Seventy Swiss albino mice were orally infected by 300 Trichinella spiralis (T. spiralis) larvae. Mice were divided into infected untreated control group and infected groups treated with 50 mg kg-1 MBZ and 300 mg kg-1 ART for three and five consecutive days, respectively, at the enteral phase [2-4 days post infection (PI)], invasive phase (10-12 days PI) and encapsulated phase (28-30 days PI). All mice were sacrificed 35-42 days PI. MBZ and ART revealed a significant decrease in mean larval counts and increase of larval per cent reduction (LR %) when treatment was initiated during the enteral phase compared to the other phases. MBZ showed significantly higher LR % (99.7, 83.95 and 89.65%) than ART (80.58, 67.0 and 79.2%) when administered at the three infection phases. Histopathological study showed a decrease in the number of encysted larvae, their surrounding cellular infiltrates and increased regenerative muscles in all treated mice. In conclusion, ART possesses a substantial anthelmintic activity against T. spiralis infection in mice both at the enteral and encapsulated phases, yet, significantly lower than MBZ.

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.

Time-resolved transcriptional profiling of Trichinella-infected murine myocytes helps to elucidate host-pathogen interactions in the muscle stage

Background

Parasites of the genus Trichinella are the pathogenic agents of trichinellosis, which is a widespread and severe foodborne parasitic disease. Trichinella spiralis resides primarily in mammalian skeletal muscle cells. After invading the cells of the host organism, T. spiralis must elude or invalidate the host’s innate and adaptive immune responses to survive. It is necessary to characterize the pathogenesis of trichinellosis to help to prevent the occurrence and further progression of this disease. The aims of this study were to elucidate the mechanisms of nurse cell formation, pathogenesis and immune evasion of T. spiralis, to provide valuable information for further research investigating the basic cell biology of Trichinella-infected muscle cells and the interaction between T. spiralis and its host.

Methods

We performed transcriptome profiling by RNA sequencing to identify global changes at 1, 3, 7, 10 and 15 days post-infection (dpi) in gene expression in the diaphragm after the parasite entered and persisted within the murine myocytes; the mice were infected by intravenous injection of newborn larvae. Gene expression analysis was based on the alignment results. Differentially expressed genes (DEGs) were identified based on their expression levels in various samples, and functional annotation and enrichment analysis were performed.

Results

The most extensive and dynamic gene expression responses in host diaphragms were observed during early infection (1 dpi). The number of DEGs and genes annotated in the Kyoto Encyclopedia of Genes and Genomes and Gene Ontology databases decreased significantly in the infected mice compared to the uninfected mice at 3 and 7 dpi, suddenly increased sharply at 10 dpi, and then decreased to a lower level at 15 dpi, similar to that observed at 3 and 7 dpi. The massive initial reaction of the murine muscle cells to Trichinella infection steadied in the later stages of infection, with little additional changes detected for the remaining duration of the studied process. Although there were hundreds of DEGs at each time point, only 11 genes were consistently up- or downregulated at all 5 time points.

Conclusions

The gene expression patterns identified in this study can be employed to characterize the coordinated response of T. spiralis-infected myocytes in a time-resolved manner. This comprehensive dataset presents a distinct and sensitive picture of the interaction between host and parasite during intracellular infection, which can help to elucidate how pathogens evade host defenses and coordinate the biological functions of host cells to survive in the mammalian environment.

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.

Mycobacterium-Induced Th1, Helminths-Induced Th2 Cells and the Potential Vaccine Candidates for Allergic Asthma: Imitation of Natural Infection

Bronchial asthma is one of the most chronic pulmonary diseases and major public health problems. In general, asthma prevails in developed countries than developing countries, and its prevalence is increasing in the latter. For instance, the hygiene hypothesis demonstrated that this phenomenon resulted from higher household hygienic standards that decreased the chances of infections, which would subsequently increase the occurrence of allergy. In this review, we attempted to integrate our knowledge with the hygiene hypothesis into beneficial preventive approaches for allergic asthma. Therefore, we highlighted the studies that investigated the correlation between allergic asthma and the two different types of infections that induce the two major antagonizing arms of T cells. This elucidation reflects the association between various types of natural infections and the immune system, which is predicted to support the main objective of the current research on investigating of the benefits of natural infections, regardless their immune pathways for the prevention of allergic asthma. We demonstrated that natural infection with Mycobacterium tuberculosis (Mtb) prevents the development of allergic asthma, thus Bacille Calmette-Guérin (BCG) vaccine is suggested at early age to mediate the same prevention particularly with increasing its efficiency through genetic engineering-based modifications. Likewise, natural helminth infections might inhabit the allergic asthma development. Therefore, helminth-derived proteins at early age are good candidates for designing vaccines for allergic asthma and it requires further investigation. Finally, we recommend imitation of natural infections as a general strategy for preventing allergic asthma that increased dramatically over the past decades.

Trichinella spiralis Calreticulin S-Domain Binds to Human Complement C1q to Interfere With C1q-Mediated Immune Functions

Helminths develop strategies to escape host immune responses that facilitate their survival in the hostile host immune environment. Trichinella spiralis, a tissue-dwelling nematode, has developed a sophisticated strategy to escape complement attack. Our previous study demonstrated that T. spiralis secretes calreticulin (TsCRT) to inhibit host classical complement activation through binding to C1q; however, the C1q binding site in TsCRT and the specific mechanism involved with complement-related immune evasion remains unknown. Using molecular docking modeling and fragment expression, we determined that TsCRT-S, a 153-aa domain of TsCRT, is responsible for C1q binding. Recombinant TsCRT-S protein expressed in Escherichia coli had the same capacity to bind and inhibit human C1q-induced complement and neutrophil activation, as full-length TsCRT. TsCRT-S inhibited neutrophil reactive oxygen species and elastase release by binding to C1q and reduced neutrophil killing of newborn T. spiralis larvae. Binding of TsCRT-S to C1q also inhibited formation of neutrophil extracellular traps (NETs), which are involved in autoimmune pathologies and have yet to be therapeutically targeted. These findings provide evidence that the TsCRT-S fragment, rather than the full-length TsCRT, is a potential target for vaccine or therapeutic development for trichinellosis, as well as for complement-related autoimmune disease therapies.

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 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.

Preliminary Trichinella spiralis Infection Ameliorates Subsequent RSV Infection-Induced Inflammatory Response

Respiratory syncytial virus (RSV) infection affects the lives of neonates throughout the globe, causing a high rate of mortality upon hospital admission. Yet, therapeutic options to deal with this pulmonary pathogen are currently limited. Helminth therapy has been well received for its immunomodulatory role in hosts, which are crucial for mitigating a multitude of diseases. Therefore, in this study, we used the helminth Trichinella spiralis and assessed its capabilities for modulating RSV infection as well as the inflammatory response induced by it in mice. Our results revealed that RSV-specific antibody responses were enhanced by pre-existing T. spiralis infection, which also limited pulmonary viral replication. Diminished lung inflammation, indicated by reduced pro-inflammatory cytokines and inflammatory cell influx was confirmed, as well as through histopathological assessment. We observed that inflammation-associated nuclear factor kappa-light-chain enhancement of activated B cells (NF-κB) and its phosphorylated forms were down-regulated, whereas antioxidant-associated nuclear factor erythroid 2-related factor 2 (Nrf2) protein expression was upregulated in mice co-infected with T. spiralis and RSV. Upregulated Nrf2 expression contributed to increased antioxidant enzyme expression, particularly NQO1 which relieved the host of oxidative stress-induced pulmonary inflammation caused by RSV infection. These findings indicate that T. spiralis can mitigate RSV-induced inflammation by upregulating the expression of antioxidant enzymes.

In vivo and in vitro studies using Clonorchis sinensis adult-derived total protein (CsTP) on cellular function and inflammatory effect in mouse and cell model

Clonorchis sinensis (C. sinensis) can induce a food-borne parasitic disease (clonorchiasis). Numerous studies have analyzed functional proteins, immunologic factors, pro-inflammatory cytokines, and cell signaling transduction that promote the development of clonorchiasis. In a previous study, it was shown that C. sinensis adult-derived total protein (CsTP) might be involved in the pathogenesis and development of liver fibrosis via bringing about Th2 immune response. In the present study, further investigation of CsTP on cellular function and inflammatory effect in vitro and in vivo has been elicited. CsTP induced inflammation and autophagy as evidenced by upregulation of TNF-α, IFN-γ, and autophagic markers LC3B and P62. Exposed to CsTP upregulated the antiapoptotic gene Bcl-2 expression, diminished the apoptosis induced by H₂O₂, but promoted the proliferation and migration of LX-2 cells in proper concentration range. Additionally, the protein levels of p-AKT and p-mTOR were repressed in response to CsTP, suggesting a correlation of blocking the activation of mTOR/AKT signaling pathway. These results revealed that CsTP might exacerbate hepatic pathological changes by regulating cell proliferation, apoptosis, autophagy, and inflammation in the liver and LX-2 cells. Some effects might be partially involved in the mTOR and AKT pathways.

Important Role of Immunological Responses to Environmental Exposure in the Development of Allergic Asthma

Allergic asthma is a public health problem that affects human health and socioeconomic development. Studies have found that the prevalence of asthma has significantly increased in recent years, which has become particularly pronounced in developed countries. With rapid urbanization in China in the last 3 decades, the prevalence of asthma has increased significantly in urban areas. As changes in genetic backgrounds of human populations are limited, environmental exposure may be a major factor that is responsible for the increased prevalence of asthma. This review focuses on environmental components of farms and rural areas that may have protective effects in reducing the development of asthma. Farm and rural related microorganism- and pathogen-associated molecular patterns are considered to be important environmental factors that modulate host's innate and adaptive immune system to induce protection effects later in life. Environmental microbial-related immunotherapy will also be discussed as the future research direction for the prevention of allergic asthma.