Helminth regulation of host IL-4Ralpha/Stat6 signaling: mechanism underlying NOS-2 inhibition by Trichinella spiralis

Interleukin-13 partly induced by the NLRP3 inflammasome promotes Trichinella spiralis encapsulation in infected mice

Trichinella spiralis infection is a serious parasitic zoonosis in which a collagenous capsule surrounding the larva is developed in the striated muscle cells. However, the mechanism of T. spiralis encapsulation is currently poorly understood. It has been reported that T. spiralis infection can induce the production of IL-13 via the NLRP3 inflammasome, and it has also been suggested IL-13 thus produced may be involved in T. spiralis encapsulation. This research aimed to clarify the involvement of NLRP3 and IL-13 in the T. spiralis capsule formation process. IL-13 and NLRP3 inhibitors were used in a T. spiralis infected mouse model and in C2C12 cells to analyze the role of IL-13 and NLRP3 in encapsulation. The results showed that T. spiralis infection significantly increased the expression levels of IL-13 and collagen IV and VI. The production of collagen around the T. spiralis encapsulation zone was significantly inhibited when an IL-13 inhibitor was applied. Moreover, the expression levels of IL-13 and collagen IV and VI were significantly decreased by the NLRP3 inhibitor in vitro and in vivo. The above results indicated that NLRP3 can participate in the development of T. spiralis encapsulation by regulating IL-13 expression and stimulating collagen IV and VI synthesis during T. spiralis infection.

Trichinella spiralis Larval Extract as a Biological Anti-Tumor Therapy in a Murine Model of Ehrlich Solid Carcinoma

Trichinella spiralis (T. spiralis) is an immunomodulating parasite that can adversely affect tumor growth and extend host lifespan. The aim of this study was to elucidate the mechanisms by which T. spiralis larval antigens achieve this effect using Ehrlich solid carcinoma (ESC) murine model. Assessment was done by histopathological and immunohistochemical analysis of caspase-3, TNF-α, Ki-67 and CD31. Additionally, Bcl2 and Bcl2-associated protein X (Bax) relative gene expression was assessed by molecular analysis for studying the effect of T. spiralis crude larval extract (CLE) antigen on tumor necrosis, apoptosis, cell proliferation and angiogenesis. We found that both T. spiralis infection and CLE caused a decrease in the areas of necrosis in ESC. Moreover, they led to increased apoptosis through activation of caspase-3, up-regulation of pro-apoptotic gene, Bax and down-regulation of anti-apoptotic gene, Bcl2. Also, T. spiralis infection and CLE diminished ESC proliferation, as evidenced by decreasing Ki-67. T. spiralis infection and CLE were able to suppress the development of ESC by inhibiting tumor proliferation, inducing apoptosis and decreasing tumor necrosis, with subsequent decrease in tumor metastasis. T. spiralis CLE antigen may be considered as a promising complementary immunotherapeutic agent in the treatment of cancer.

Differentiation and Regulation of Bovine Th2 Cells In Vitro

Bovine Th2 cells have usually been characterized by IL4 mRNA expression, but it is unclear whether their IL4 protein expression corresponds to transcription. We found that grass-fed healthy beef cattle, which had been regularly exposed to parasites on the grass, had a low frequency of IL4+ Th2 cells during flow cytometry, similar to animals grown in feedlots. To assess the distribution of IL4+ CD4+ T cells across tissues, samples from the blood, spleen, abomasal (draining), and inguinal lymph nodes were examined, which revealed limited IL4 protein detection in the CD4+ T cells across the examined tissues. To determine if bovine CD4+ T cells may develop into Th2 cells, naïve cells were stimulated with anti-bovine CD3 under a Th2 differentiation kit in vitro. The cells produced primarily IFNγ proteins, with only a small fraction (<10%) co-expressing IL4 proteins. Quantitative PCR confirmed elevated IFNγ transcription but no significant change in IL4 transcription. Surprisingly, GATA3, the master regulator of IL4, was highest in naïve CD4+ T cells but was considerably reduced following differentiation. To determine if the differentiated cells were true Th2 cells, an unbiased proteomic assay was carried out. The assay identified 4212 proteins, 422 of which were differently expressed compared to those in naïve cells. Based on these differential proteins, Th2-related upstream components were predicted, including CD3, CD28, IL4, and IL33, demonstrating typical Th2 differentiation. To boost IL4 expression, T cell receptor (TCR) stimulation strength was reduced by lowering anti-CD3 concentrations. Consequently, weak TCR stimulation essentially abolished Th2 expansion and survival. In addition, extra recombinant bovine IL4 (rbIL4) was added during Th2 differentiation, but, despite enhanced expansion, the IL4 level remained unaltered. These findings suggest that, while bovine CD4+ T cells can respond to Th2 differentiation stimuli, the bovine IL4 pathway is not regulated in the same way as in mice and humans. Furthermore, Ostertagia ostertagi (OO) extract, a gastrointestinal nematode in cattle, inhibited signaling via CD3, CD28, IL4, and TLRs/MYD88, indicating that external pathogens can influence bovine Th2 differentiation. In conclusion, though bovine CD4+ T cells can respond to IL4-driven differentiation, IL4 expression is not a defining feature of differentiated bovine Th2 cells.

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.

Eosinophil-Mediated Immune Control of Adult Filarial Nematode Infection Can Proceed in the Absence of IL-4 Receptor Signaling

Immunity to chronic filarial worm infection is apparent in IL-4Rα–deficient mice.

Delayed immunity in IL-4Rα^−/− mice is due to suboptimal tissue eosinophilia.

Eosinophil recruitment in the absence of IL-4R signaling requires CCR3 and IL-5.

Helminth infections are accompanied by eosinophilia in parasitized tissues. Eosinophils are effectors of immunity to tissue helminths. We previously reported that in the context of experimental filarial nematode infection, optimum tissue eosinophil recruitment was coordinated by local macrophage populations following IL-4R–dependent in situ proliferation and alternative activation. However, in the current study, we identify that control of chronic adult filarial worm infection is evident in IL-4Rα–deficient (IL-4Rα^−/−) mice, whereby the majority of infections do not achieve patency. An associated residual eosinophilia was apparent in infected IL-4Rα^−/− mice. By treating IL-4Rα^−/− mice serially with anti-CCR3 Ab or introducing a compound deficiency in CCR3 within IL-4Rα^−/− mice, residual eosinophilia was ablated, and susceptibility to chronic adult Brugia malayi infection was established, promoting a functional role for CCR3-dependent eosinophil influx in immune control in the absence of IL-4/IL-13–dependent immune mechanisms. We investigated additional cytokine signals involved in residual eosinophilia in the absence IL-4Rα signaling and defined that IL-4Rα^−/−/IL-5^−/− double-knockout mice displayed significant eosinophil deficiency compared with IL-4Rα^−/− mice and were susceptible to chronic fecund adult filarial infections. Contrastingly, there was no evidence that either IL-4R–dependent or IL-4R–independent/CCR3/IL-5–dependent immunity influenced B. malayi microfilarial loads in the blood. Our data demonstrate multiplicity of Th2-cytokine control of eosinophil tissue recruitment during chronic filarial infection and that IL-4R–independent/IL-5– and CCR3-dependent pathways are sufficient to control filarial adult infection via an eosinophil-dependent effector response prior to patency.

Hepatocellular carcinoma-associated antigen 59 of Haemonchus contortus modulates the functions of PBMCs and the differentiation and maturation of monocyte-derived dendritic cells of goats in vitro

BACKGROUND

Hepatocellular carcinoma-associated antigen 59 (HCA59), which is one of the most important excretory/secretory products of Haemonchus contortus (HcESPs), is known to have antigenic functions. However, its immunomodulatory effects on host cells are poorly understood.

METHODS

Here, we cloned the HCA59 gene and expressed the recombinant protein of HCA59 (rHCA59). Binding activities of rHCA59 to goat peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs) were checked by immunofluorescence assay (IFA) and the immunoregulatory effects of rHCA59 on cytokine secretions, cell migration, cell proliferation, nitric oxide production, and changes in expression of genes in related pathways were observed by co-incubation of rHCA59 with goat PBMCs and DCs. Monocyte phagocytosis and characterization of goat blood DC subsets were detected by flow cytometry.

RESULTS

The IFA results revealed that rHCA59 could bind to PBMCs and DCs. Treatment of PBMCs with rHCA59 significantly increased cellular proliferation and NO production in a dose-dependent manner, while cell migration was vigorously blocked. Treatment with rHCA59 significantly suppressed monocytes phagocytosis. The quantity of surface marker CD80 on DCs increased significantly after rHCA59 treatment. In addition, the expression of genes included in the WNT pathway was related to the differentiation and maturation of DCs, and the production of IL-10 and IL-17 produced by PBMCs was altered.

CONCLUSIONS

Our findings illustrated that rHCA59 could enhance host immune responses by regulating the functions of goat PBMCs and DCs, which would benefit our understanding of HCA59 from parasitic nematodes contributing to the mechanism of parasitic immune evasion.

Kinetics Evaluation of IgM and IgG Levels in the Mice Infected with Trichinella spiralis Experimentally Using ES Antigens from Different Developmental Stages of the Parasite

BACKGROUND

To assay the Trichinella-specific IgM and IgG antibody responses during the early stage of infection, serum was collected from mice infected with the muscle larvae (ML) of T. spiralis (ISS534) at different dpi (days post infection) up to 60 days.

METHODS

The levels of IgM and IgG antibodies in serum were measured by ES antigens from different stage of T. spiralis using the ELISA method in Shanghai, China in 2017.

RESULTS

The anti-Trichinella IgM and IgG could be detected by ES antigens from the adult three days worm (Ad3) as early as 5 dpi and 8 dpi, respectively. ES antigens from the mixture of adult six days worm & new born larvae (Ad6+NBL) was similar to Ad3. When antibodies were detected by these two antigens, the levels of IgM peaked at 14 dpi and then declined from 15 dpi to 60 dpi; the IgG peaked at 20 dpi, and gradually declined, however, higher detection levels were maintained until 60 dpi.

CONCLUSION

Ad3 ES antigens showed more antigenicity than Ad6+NBL ES on titer detection of IgM and IgG antibodies, and the production of Ad3 ES is easier. In terms of early diagnosis, these two antigens are better than the ML ES antigens of T. spiralis, which antibodies could not be detected before 20dpi. Ad3 ES antigens might be good candidate for the early diagnosis of trichinellosis or the mixture of Ad3 and Ad6+NBL ES might be used.

Recombinant Haemonchus contortus 24 kDa excretory/secretory protein (rHcES-24) modulate the immune functions of goat PBMCs in vitro

A 24 kDa protein is one of the important components in Haemonchus contortus (barber pole worm) excretory/secretory products (HcESPs), which was shown to have important antigenic function. However, little is known about the immunomodulatory effects of this proteinon host cell. In the present study gene encoding 24kDa excretory/secretory protein (HcES-24) was cloned. The recombinant protein of HcES-24 (rHcES-24) was expressed in a histidine-tagged fusion protein soluble form in Escherichia coli. Binding activity of rHcES-24 to goat PBMCs was confirmed by immunofluorescence assay (IFA) and its immunomudulatory effect on cytokine secretion, cell proliferation, cell migration and nitric oxide production were observed by co-incubation of rHcES-24. IFA results revealed that rHcES-24 could bind to the PBMCs. The interaction of rHcES-24 increased the production of IL4, IL10, IL17 and cell migration in dose dependent manner. However, rHcES-24 treatment significantly suppressed the production of IFNγ, proliferation of the PBMC and Nitric oxide (NO) production. Our findings showed that the rHcES-24 played important regulatory effects on the goat PBMCs.

Sweet secrets of a therapeutic worm: mass-spectrometric N-glycomic analysis of Trichuris suis

Trichuris suis, a nematode parasite of pigs, has attracted attention as its eggs have been administered to human patients as a potential therapy for inflammatory diseases. The immunomodulatory factors remain molecularly uncharacterised, but in vitro studies suggest that glycans on the parasite's excretory/secretory proteins may play a role. Using an off-line LC-MS approach in combination with chemical and enzymatic treatments, we have examined the N-linked oligosaccharides of T. suis. In addition to the paucimannosidic and oligomannosidic N-glycans typical of many invertebrates, a number of glycans carry N,N'-diacetyllactosamine (LacdiNAc) modified by fucose and/or phosphorylcholine. Such antennal epitopes are similar to ones previously associated with immunomodulation by helminths; here we propose phosphorylcholine modifications predominantly of terminal N-acetylgalactosamine but also of subterminal α1,3-fucosylated N-acetylglucosamine. Exact knowledge of the glycome of T. suis will facilitate more targeted studies on glycan receptors in the host as well as the engineering of cell lines to produce correctly glycosylated recombinant forms of candidate proteins for future studies on immunomodulation.

The potential for genetically altered microglia to influence glioma treatment

Diffuse and unstoppable infiltration of brain and spinal cord tissue by neoplastic glial cells is the single most important therapeutic problem posed by the common glioma group of tumors: astrocytoma, oligoastrocytoma, oligodendroglioma, their malignant variants and glioblastoma. These neoplasms account for more than two thirds of all malignant central nervous system tumors. However, most glioma research focuses on an examination of the tumor cells rather than on host-specific, tumor micro-environmental cells and factors. This can explain why existing diffuse glioma therapies fail and why these tumors have remained incurable. Thus, there is a great need for innovation. We describe a novel strategy for the development of a more effective treatment of diffuse glioma. Our approach centers on gaining control over the behavior of the microglia, the defense cells of the CNS, which are manipulated by malignant glioma and support its growth. Armoring microglia against the influences from glioma is one of our research goals. We further discuss how microglia precursors may be genetically enhanced to track down infiltrating glioma cells.

Regulation of IL-4 receptor signaling by STUB1 in lung inflammation

RATIONALE

IL-4Rα, the common receptor component for IL-4 and IL-13, plays a critical role in IL-4- and IL-13-mediated signaling pathways that regulate airway inflammation and remodeling. However, the regulatory mechanisms underlying IL-4Rα turnover and its signal termination remain elusive.

OBJECTIVES

To evaluate the role of STUB1 (STIP1 homology and U-Box containing protein 1) in regulating IL-4R signaling in airway inflammation.

METHODS

The roles of STUB1 in IL-4Rα degradation and its signaling were investigated by immunoblot, immunoprecipitation, and flow cytometry. The involvement of STUB1 in airway inflammation was determined in vivo by measuring lung inflammatory cells infiltration, mucus production, serum lgE levels, and alveolar macrophage M2 activation in STUB1(-/-) mice. STUB1 expression was evaluated in airway epithelium of patients with asthma and lung tissues of subjects with chronic obstructive pulmonary disease.

MEASUREMENTS AND MAIN RESULTS

STUB1 interacted with IL-4Rα and targeted it for ubiquitination-mediated proteasomal degradation, terminating IL-4 or IL-13 signaling. STUB1 knockout cells showed increased levels of IL-4Rα and sustained STAT6 activation, whereas STUB1 overexpression reduced IL-4Rα levels. Mice deficient in STUB1 had spontaneous airway inflammation, alternative M2 activation of alveolar macrophage, and increased serum IgE. STUB1 levels were increased in airways of subjects with asthma or chronic obstructive pulmonary disease, suggesting that up-regulation of STUB1 might be an important feedback mechanism to dampen IL-4R signaling in airway inflammation.

CONCLUSIONS

Our study identified a previously uncharacterized role for STUB1 in regulating IL-4R signaling, which might provide a new strategy for attenuating airway inflammation.

Coinfection with Clonorchis sinensis modulates murine host response against Trichinella spiralis infection

Concomitant infections of different species of parasites are common in the field. Infection with one parasite species likely triggers host responses that may influence the subsequent infection of another species and alter disease outcomes. So far, the majority of studies have focused on single species parasite infection, and the mechanisms of protection induced by the first parasite infection against the secondary infection remain poorly defined. In this study, we assess the impact of trematode Clonorchis sinensis infection on the course of another tissue nematode Trichinella spiralis challenge. We observed that mice with preexisting C. sinensis infection had lower worm burden of intestinal T. spiralis than those infected with T. spiralis alone; mice with preexisting C. sinensis also had severe enteric histopathological changes and higher counts of intestinal Paneth cells in responses to T. spiralis challenge. The mRNA levels of interleukin (IL)-4, IL-10, IL-13, and tumor necrosis factor (TNF)-α from the small intestine and spleen of the different groups were analyzed using quantitative real-time polymerase chain reaction. Compared with that in mice infected with T. spiralis alone, the mRNA expression of IL-13 was significantly increased in the small intestine tissues and IL-4, IL-13, and TNF-α were significantly increased in the spleen tissues in the dually infected mice. Our findings suggest that a "preexisting" trematode infection of C. sinensis is a factor which contributes to reducing the establishment of T. spiralis adult worms in the small intestine.

Helminth infection and type 1 diabetes

The increasing incidence of type 1 diabetes (T1D) and autoimmune diseases in industrialized countries cannot be exclusively explained by genetic factors. Human epidemiological studies and animal experimental data provide accumulating evidence for the role of environmental factors, such as infections, in the regulation of allergy and autoimmune diseases. The hygiene hypothesis has formally provided a rationale for these observations, suggesting that our co-evolution with pathogens has contributed to the shaping of the present-day human immune system. Therefore, improved sanitation, together with infection control, has removed immunoregulatory mechanisms on which our immune system may depend. Helminths are multicellular organisms that have developed a wide range of strategies to manipulate the host immune system to survive and complete their reproductive cycles successfully. Immunity to helminths involves profound changes in both the innate and adaptive immune compartments, which can have a protective effect in inflammation and autoimmunity. Recently, helminth-derived antigens and molecules have been tested in vitro and in vivo to explore possible applications in the treatment of inflammatory and autoimmune diseases, including T1D. This exciting approach presents numerous challenges that will need to be addressed before it can reach safe clinical application. This review outlines basic insight into the ability of helminths to modulate the onset and progression of T1D, and frames some of the challenges that helminth-derived therapies may face in the context of clinical translation.

Mesenchymal stem cells: a double-edged sword in regulating immune responses

Mesenchymal stem cells (MSCs) have been employed successfully to treat various immune disorders in animal models and clinical settings. Our previous studies have shown that MSCs can become highly immunosuppressive upon stimulation by inflammatory cytokines, an effect exerted through the concerted action of chemokines and nitric oxide (NO). Here, we show that MSCs can also enhance immune responses. This immune-promoting effect occurred when proinflammatory cytokines were inadequate to elicit sufficient NO production. When inducible nitric oxide synthase (iNOS) production was inhibited or genetically ablated, MSCs strongly enhance T-cell proliferation in vitro and the delayed-type hypersensitivity response in vivo. Furthermore, iNOS^−/− MSCs significantly inhibited melanoma growth. It is likely that in the absence of NO, chemokines act to promote immune responses. Indeed, in CCR5^−/−CXCR3^−/− mice, the immune-promoting effect of iNOS^−/− MSCs is greatly diminished. Thus, NO acts as a switch in MSC-mediated immunomodulation. More importantly, the dual effect on immune reactions was also observed in human MSCs, in which indoleamine 2,3-dioxygenase (IDO) acts as a switch. This study provides novel information about the pathophysiological roles of MSCs.

Role for nitric oxide in hookworm-associated immune suppression

Hookworm infection is a major cause of anemia and malnutrition in resource-poor countries. Human and animal studies suggest that infection with these intestinal nematodes is associated with impaired cellular immunity, characterized by reduced lymphocyte proliferation in response to both parasite and heterologous antigens. We report here data from studies aimed at defining mechanisms through which hookworms modulate the host cellular immune response. Splenocytes and mesenteric lymph node (MLN) cells from hamsters infected with Ancylostoma ceylanicum showed minimal proliferation in response to mitogen at days 20 and 30 postinfection (p.i.), with partial recovery noted at day 70 p.i. The proliferative capacity of enriched splenocyte T-cell preparations from infected animals following stimulation with hookworm antigens was partially restored in the presence of antigen-presenting cells from uninfected hamsters. Analysis by fluorescence-activated cell sorting revealed that hookworm infection is associated with reduced percentages of both CD4(+) and surface immunoglobulin G-positive lymphocytes in the spleen and MLN cells. Splenocytes from infected hamsters also secreted more nitric oxide (NO) in culture than did those from naïve animals. Inhibition of NO secretion was associated with partial restoration of the proliferative capacity of splenocytes from infected animals in response to concanavalin A, suggesting a role for NO in mediating this effect. Together, these data demonstrate that hookworm infection is associated with impaired function of antigen-presenting cells and depletion of important lymphocyte subpopulations and also suggests a role for NO in parasite-induced immunosuppression.

Proteomic Modification by Nitric Oxide

The role of nitric oxide (NO) in cellular signaling has become one of the most rapidly growing areas in biology during the past two decades. As a gas and free radical with an unshared electron, nitric oxide participates in various biological processes. The interaction between NO and proteins may be roughly divided into two categories. In many instances, NO mediates its biological effects by activating guanylyl cyclase and elevates intracellular cyclic GMP synthesis from GTP. However, the list of cGMP-independent effects of NO is also growing at a rapid rate. In this review, the importance and relevance of nitrotyrosine formation are stressed. The utilization of intact cell cultures, tissues, and cell-free preparations along with the use of pharmacological, biochemical, and molecular biological approaches to characterize, purify, and reconstitute these NO regulatory pathways could lead to the development of new therapies for various pathological conditions that are characterized by unbalanced production of NO.

The beneficial helminth parasite?

There is unequivocal evidence that parasites influence the immune activity of their hosts, and many of the classical examples of this are drawn from assessment of helminth infections of their mammalian hosts. Thus, helminth infections can impact on the induction or course of other diseases that the host might be subjected to. Epidemiological studies demonstrate that world regions with high rates of helminth infections consistently have reduced incidences of autoimmune and other allergic/inflammatory-type conditions. Here I review and assess the possible ways by which helminth infections can block or modulate concomitant disease processes. There is much to be learned from careful analysis of immuno-regulation in helminth-infected rodents and from an understanding of the immune status of acutely and chronically infected humans. The ultimate reward from this type of investigation will likely be a more comprehensive knowledge of immunity, novel ways to intervene in the immune response to alleviate autoimmune and allergic diseases (growing concerns in economically developed areas), and perhaps the development of helminth therapy for patients suffering from specific inflammatory, autoimmune or allergic disorders.