Trichinella spiralis: modulation of experimental autoimmune encephalomyelitis in DA rats

Prior Trichinella spiralis infection protects against Schistosoma mansoni induced hepatic fibrosis

Background

Schistosomiasis affects approximately 250 million people worldwide, with 200,000 deaths annually. It has been documented that the granulomatous response to Schistosoma mansoni (S. mansoni) oviposition is the root cause of progressive liver fibrosis in chronic infection, in 20% of the patients, and can lead to liver cirrhosis and/or liver cancer. The influence of helminths coinfection on schistosomiasis-induced liver pathological alterations remains poorly understood. Therefore, in this study, we investigated the effect of Trichinella spiralis (T. spiralis) infection on S. mansoni-induced hepatic fibrosis.

Materials and methods

Thirty adult male Balb-c mice were divided into three groups. Group 1 was left uninfected; group 2 was infected with S. mansoni cercariae and group 3 was orally infected with T. spiralis larvae, then 28 days later, this group was infected with S. mansoni cercariae. All groups were sacrificed at the end of the 8th week post infection with S. mansoni to evaluate the effect of pre-infection with T. spiralis on S. mansoni induced liver fibrosis was evaluated parasitologically (worm burden and egg count in tissues), biochemically (levels of alanine aminotransferase and aspartate aminotransferase), histopathologically (H&E and MT staining, and immunohistochemical staining for the expression of α-SMA, IL-6, IL-1β, IL-17, IL-23, TNF-α, and TGF-β).

Results

The results in the present study demonstrated marked protective effect of T. spiralis against S. mansoni induced liver pathology. We demonstrated that pre-infection with T. spirais caused marked reduction in the number of S. mansoni adult worms (3.17 ± 0.98 vs. 18 ± 2.16, P = 0.114) and egg count in both the intestine (207.2 ± 64.3 vs. 8,619.43 ± 727.52, P = 0.009) and liver tissues (279 ± 87.2 vs. 7,916.86 ± 771.34; P = 0.014). Consistently, we found significant reductions in both number (3.4 ± 1.1 vs. 11.8.3 ± 1.22; P = 0.007) and size (84 ± 11 vs. 294.3 ± 16.22; P = 0.001) of the hepatic granulomas in mice pre-infected with T. spiralis larvae compared to those infected with only S. mansoni. Furthermore, pre- infection with T. spiralis markedly reduced S. mansoni- induced hepatic fibrosis, as evidenced by decreased collagen deposition, low expression of α-SMA, and significantly reduced levels of IL-17, IL-1B, IL-6, TGF-B, IL-23, and TNF-α compared to mice infected with S. mansoni only.

Conclusions

Our data show that pre-infection with T. spiralis effectively protected mice from severe schistosomiasis and liver fibrosis. We believe that our findings support the potential utility of helminths for the preventing and ameliorating severe pathological alterations induced by schistosomiasis.

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.

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.

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.

Remote regulation of type 2 immunity by intestinal parasites

The intestinal tract is the target organ of most parasitic infections, including those by helminths and protozoa. These parasites elicit prototypical type 2 immune activation in the host's immune system with striking impact on the local tissue microenvironment. Despite local containment of these parasites within the intestinal tract, parasitic infections also mediate immune adaptation in peripheral organs. In this review, we summarize the current knowledge on how such gut-tissue axes influence important immune-mediated resistance and disease tolerance in the context of coinfections, and elaborate on the implications of parasite-regulated gut-lung and gut-brain axes on the development and severity of airway inflammation and central nervous system diseases.

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.

Trichinella spiralis excretory-secretory products downregulate MMP-9 in Dark Agouti rats affected by experimental autoimmune encephalomyelitis

Matrix metalloproteinases (MMPs), are implicated in the pathogenesis of multiple sclerosis (MS) and in its animal model, experimental autoimmune encephalomyelitis (EAE). Our aim was to investigate whether amelioration of EAE in Dark Agouti (DA) rats, induced by Trichinella spiralis muscle larvae excretory-secretory products (ES L1), could be related to the level and activity of gelatinases, MMP-9 and MMP-2. Serum levels of MMP-9, MMP-2, NGAL/MMP-9, TIMP-1, and cytokines, evaluated by gel-zymography or ELISA, as well as gelatinases and TIMP-1 expression in the spinal cord (SC), were determined in: i) EAE induced, ii) ES L1-treated EAE induced animals. Milder clinical signs in ES L1-treated EAE induced DA rats were accompanied with lower serum levels of MMP-9 and NGAL/MMP-9 complex. However, the correlation between the severity of EAE and the level of serum MMP-9 was found only in the peak of the disease, with MMP-9/TIMP-1 ratio higher in EAE animals without ES L1 treatment. Lower expression of MMP-9 in SC of ES L1-treated, EAE induced rats, correlated with the reduced number of SC infiltrating cells. In SC infiltrates, in the effector and the recovery phase, production of anti-inflammatory cytokines IL-4 and IL-10 was higher in animals treated with ES L1 prior to EAE induction, compared to untreated EAE animals. Reduced expression of MMP-9 in SC tissue, which correlated with the reduced number of infiltrating cells, might be ascribed to regulatory mechanisms, among which is IL-10.

DC-SIGN signalling induced by Trichinella spiralis products contributes to the tolerogenic signatures of human dendritic cells

Tolerogenic dendritic cells (tolDCs) are central players in the maintenance of immune tolerance and thereby have been identified as the most favourable candidates for cell therapy of autoimmune diseases. We have recently shown that excretory-secretory products (ES L1) released by Trichinella spiralis larvae induce stable human tolDCs in vitro via Toll-like receptor 2 (TLR2) and TLR4. However, engagement of these receptors did not fully explain the tolerogenic profile of DCs. Here, we observed for the first time that dendritic cell-specific ICAM-3 grabbing non-integrin (DC-SIGN) interacts with highly glycosylated ES L1 and contributes to the generation of ES L1-induced tolDCs. Blocking DC-SIGN interfered with the ES L1-induced higher expression of CD40 and CCR7 and the production of IL-10 and TGF-β by DCs. The cooperation of TLR2, TLR4 and DC-SIGN receptors is of importance for the capacity of DCs to prime T cell response toward Th2 and to induce expansion of CD4+CD25+Foxp3+ T cells, as well as for the production of IL-10 and TGF-β by these cells. Overall, these results indicate that induction of tolDCs by ES L1 involves engagement of multiple pattern recognition receptors namely, TLR2, TLR4 and DC-SIGN.

Regulation of immunity and allergy by helminth parasites

There is increasing interest in helminth parasite modulation of the immune system, both from the fundamental perspective of the "arms race" between host and parasite, and equally importantly, to understand if parasites offer new pathways to abate and control untoward immune responses in humans. This article reviews the epidemiological and experimental evidence for parasite down-regulation of host immunity and immunopathology, in allergy and other immune disorders, and recent progress towards defining the mechanisms and molecular mediators which parasites exploit in order to modulate their host. Among these are novel products that interfere with epithelial cell alarmins, dendritic cell activation, macrophage function and T-cell responsiveness through the promotion of an immunoregulatory environment. These modulatory effects assist parasites to establish and survive, while dampening immune reactivity to allergens, autoantigens and microbiome determinants.

Primary characterization of the immune response in pigs infected with Trichinella spiralis

Trichinellosis, which is caused by Trichinella spiralis (T. spiralis), is a serious zoonosis. Pigs play an important role in the transmission of human trichinellosis. Characterizing the immune response to T. spiralis infection is key to elucidating host–parasite interactions. However, most studies on the immune response to T. spiralis infection have employed murine models. In this study, we investigated the immune response to T. spiralis infection in pigs. The results showed that the average numbers of larvae per gram (lpg) for the 100-muscle larvae (ML), 1000-ML, and 10 000-ML groups were 1.502, 35.947, and 398.811, respectively. The percentages of CD3+ T cells, B cells, CD4+ T cells, Treg cells, and Th17 cells were elevated in the infection groups compared to the control animals. In contrast, CD8+ T cell percentages were reduced after infection in the low-dose group. The number of neutrophils was increased at 3–17 days post-infection (dpi). Th1 cytokine IL-2 levels were significantly decreased at 7 dpi, and Th2 cytokine IL-4 levels were significantly elevated at 3 dpi. Treg cytokine IL-10 levels were significantly elevated between 7 dpi and 30 dpi. Th17 cytokine IL-17A levels were significantly increased beginning at 11 dpi. These results confirmed that pigs infected with T. spiralis predominantly induced Th2 and Treg immune responses, which suppress the Th1 immune responses. This study provides novel insights into the immune response of pigs infected with T. spiralis.

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.

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

Background

Helminths immunomodulate the host immune system by secreting proteins to create an inhibitory environment as a strategy for survival in the host. As a bystander effect, this balances the host immune system to reduce hypersensitivity to allergens or autoantigens. Based on this, helminth therapy has been used to treat some allergic or autoimmune diseases. As a tissue-dwelling helminth, Trichinella spiralis infection has been identified to have strong immunomodulatory effects; the effective components in the worm have not yet been identified.

Methods

The soluble extracts of T. spiralis adult worms and muscle larvae were used to treat airway inflammation before and after an ovalbumin (OVA)-sensitization/challenge in an OVA-induced asthma mouse model. The therapeutic effects were observed by measuring the level of inflammation in the lungs.

Results

The soluble products derived from T. spiralis parasites, especially from adult worms, were able to ameliorate OVA-induced airway inflammatory responses which were associated with reduced eosinophil infiltration, OVA-specific IgE, Th2 cytokine IL-4, and increased IL-10 and TGF-β. The stimulation of the Treg response may contribute to the alleviated allergic inflammation.

Conclusions

Trichinella spiralis worm extracts stimulate regulatory cytokines that are associated with reduced allergic airway inflammation. The identification of effective components in the adult worm extracts will be a crucial approach for developing a novel therapeutic for allergic and autoimmune diseases.

Role of mast cells in the generation of a T-helper type 2 dominated anti-helminthic immune response

Mast cells are long-lived, innate immune cells of the myeloid lineage which are found in peripheral tissues located throughout the body, and positioned at the interface between the host and the environment. Mast cells are found in high concentrations during helminth infection. Using Kitw-sh mast cell deficient mice, a recently published study in Bioscience Reports by Gonzalez et al. (Biosci. Rep., 2018) focused on the role of mast cells in the immune response to infection by the helminth Hymenolepis diminuta The authors showed that mast cells play a role in the modulation of Th2 immune response characterized by a unique IL-4, IL-5 and IL-13 cytokine profile, as well as subsequent robust worm expulsion during H. diminuta infection. Unlike WT mice which expelled H. diminuta at day 10, Kitw-sh deficient mice displayed delayed worm expulsion (day 14 post infection). Further, a possible role for mast cells in the basal expression of cytokines IL-25, IL-33 and thymic stromal lymphopoietin was described. Deletion of neutrophils in Kitw-sh deficient mice enhanced H. diminuta expulsion, which was accompanied by splenomegaly. However, interactions between mast cells and other innate and adaptive immune cells during helminth infections are yet to be fully clarified. We conclude that the elucidation of mechanisms underlying mast cell interactions with cells of the innate and adaptive immune system during infection by helminths can potentially uncover novel therapeutic applications against inflammatory, autoimmune and neoplastic diseases.

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

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

Novel Therapeutics for Multiple Sclerosis Designed by Parasitic Worms

The evolutionary response to endemic infections with parasitic worms (helminth) was the development of a distinct regulatory immune profile arising from the need to encapsulate the helminths while simultaneously repairing tissue damage. According to the old friend's hypothesis, the diminished exposure to these parasites in the developed world has resulted in a dysregulated immune response that contributes to the increased incidence of immune mediated diseases such as Multiple Sclerosis (MS). Indeed, the global distribution of MS shows an inverse correlation to the prevalence of helminth infection. On this basis, the possibility of treating MS with helminth infection has been explored in animal models and phase 1 and 2 human clinical trials. However, the possibility also exists that the individual immune modulatory molecules secreted by helminth parasites may offer a more defined therapeutic strategy.

Therapeutic potential of helminths in autoimmune diseases: helminth-derived immune-regulators and immune balance

Helminths have accompanied human throughout history by releasing immune-evasion molecules that could counteract an aberrant immune response within the host. In the past decades, helminth infections are becoming less prevalent possibly due to the developed sanitation. Meanwhile, the incidence of autoimmune diseases is increasing, which cannot be exclusively explained by the changes of susceptibility genes. While the hygiene hypothesis casts light on the problem. The infections of helminths are believed to interact with and regulate human immunity with the byproduct of suppressing the autoimmune diseases. Thus, helminths are potential to treat or cure the autoimmune diseases. The therapeutic progresses and possible immune suppression mechanisms are illustrated in the review. The helminths that are studied most intensively include Heligmosomoides polygyrus, Hymenolepis diminuta, Schistosoma mansoni, Trichinella spiralis, and Trichuris suis. Special attentions are paid on the booming animal models and clinical trials that are to detect the efficiency of immune-modulating helminth-derived molecules on autoimmune diseases. These trials provide us with a prosperous clinical perspective, but the precise mechanism of the down-regulatory immune response remains to be clarified. More efforts are needed to be dedicated until these parasite-derived immune modulators could be used in clinic to treat or cure the autoimmune diseases under a standard management.

Trichuris suis secrete products that reduce disease severity in a multiple sclerosis model

Multiple sclerosis is a chronic inflammatory central nervous system (CNS) disease, which affects about 1 in 1000 individuals in the western world. It has been suggested that this relatively high prevalence is linked to a high level of hygiene, i.e. a reduced exposure to various microorganisms, including parasites. Parasites are known to employ different immunomodulatory and antiinflammatory strategies, which enable them to evade destruction by the immune system. We have investigated the immunomodulation by the swine whipworm, Trichuris suis, by measuring the impact of oral administration of T. suis ova as well as of intraperitoneal administration of T. suis excretory/secretory products on the development and progression of experimental autoimmune encephalomyelitis - an animal model that shares clinical and pathological characteristics with multiple sclerosis. Intraperitoneal administration of excretory/secretory products before disease onset, resulted in a significant decrease in disease severity as well as markedly reduced TH1 and TH17 T-cell responses, centrally in the spinal cord as well as in the periphery, i.e. the spleen. Thus, parenteral administration of T. suis-derived products results in a skewing of the immune response with a significant impact on disease severity in a CNS inflammatory disease model.

Immunomodulatory effects of Trichinella spiralis-derived excretory-secretory antigens

Helminth-derived products, either released into the circulation during the course of the infection or isolated after in vitro cultivation of the parasite and applied by the injection, are able to suppress the host immune response to autoantigens and allergens, but mechanisms could differ. Prophylactic application of Trichinella spiralis excretory-secretory muscle larvae (ES L1) products ameliorates experimental autoimmune encephalomyelitis (EAE) with the same success as infection did. However, a shift to the Th2-type response in the periphery and in the central nervous system, accompanied by activation of regulatory mechanisms, had a striking, new feature of increased proportion of unconventional CD4(+)CD25(-)Foxp3(+) regulatory cells both in the periphery and in the central nervous system of animals treated with ES L1 before the induction of EAE.

Malaria endemicity and co-infection with tissue-dwelling parasites in Sub-Saharan Africa: a review

Mechanisms and outcomes of host-parasite interactions during malaria co-infections with gastrointestinal helminths are reasonably understood. In contrast, very little is known about such mechanisms in cases of malaria co-infections with tissue-dwelling parasites. This is lack of knowledge is exacerbated by misdiagnosis, lack of pathognomonic clinical signs and the chronic nature of tissue-dwelling helminthic infections. A good understanding of the implications of tissue-dwelling parasitic co-infections with malaria will contribute towards the improvement of the control and management of such co-infections in endemic areas. This review summarises and discusses current information available and gaps in research on malaria co-infection with gastro-intestinal helminths and tissue-dwelling parasites with emphasis on helminthic infections, in terms of the effects of migrating larval stages and intra and extracellular localisations of protozoan parasites and helminths in organs, tissues, and vascular and lymphatic circulations.

Differential immune responses in mice infected with the tissue-dwelling nematode Trichinella zimbabwensis

To improve diagnostic tools, immunotherapies and vaccine development for trichinellosis surveillance and control there is a need to understand the host immune responses induced during infection with Trichinella zimbabwensis, a tissue-dwelling nematode. In this study, we sought to determine immune responses induced in mice during T. zimbabwensis infection. The parasite strain used (Code ISS1209) was derived from a naturally infected crocodile (Crocodylus niloticus) and is the main Trichinella species prevalent in southern Africa. Sixty 6- to 8-week-old female BALB/c mice were randomly assigned to two equal groups: T. zimbabwensis-infected (n= 30) and the non-infected control group (n= 30). Levels of serum tumour necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), interleukin-4 (IL-4) as well as parasite-specific IgM, IgG, IgG1, IgG2a, IgG2b and IgG3 antibody responses were determined using enzyme-linked immunosorbent assay (ELISA). The cytokines and antibodies provided information on T-helper 1 (Th1)- and Th2-type, T-regulatory and antibody responses. Results showed that during the intestinal stage of infection, higher levels of parasite-specific IgM, IgG, IgG1 (P <  0.05) and IL-10 and TNF-α (P <  0.001) were observed in the Trichinella-infected group compared with the non-infected control group. In the parasite establishment and tissue migration phases, levels of IgG1 and IgG3 were elevated (P <  0.001), while those of IgM (P <  0.01) declined on days 21 and 35 post infection (pi) compared to the enteric phase. Our findings show that distinct differences in Th1- and Th2-type and T-regulatory responses are induced during the intestinal, tissue migration and larval establishment stages of T. zimbabwensis infection.

Secretory Products of Trichinella spiralis Muscle Larvae and Immunomodulation: Implication for Autoimmune Diseases, Allergies, and Malignancies

Trichinella spiralis has the unique ability to make itself "at home" by creating and hiding in a new type of cell in the host body that is the nurse cell. From this immunologically privileged place, the parasite orchestrates a long-lasting molecular cross talk with the host through muscle larvae excretory-secretory products (ES L1). Those products can successfully modulate parasite-specific immune responses as well as responses to unrelated antigens (either self or nonself in origin), providing an anti-inflammatory milieu and maintaining homeostasis. It is clear, based on the findings from animal model studies, that T. spiralis and its products induce an immunomodulatory network (which encompasses Th2- and Treg-type responses) that may allow the host to deal with various hyperimmune-associated disorders as well as tumor growth, although the latter still remains unclear. This review focuses on studies of the molecules released by T. spiralis, their interaction with pattern recognition receptors on antigen presenting cells, and subsequently provoked responses. This paper also addresses the immunomodulatory properties of ES L1 molecules and how the induced immunomodulation influences the course of different experimental inflammatory and malignant diseases.

Unraveling the Hygiene Hypothesis of helminthes and autoimmunity: origins, pathophysiology, and clinical applications

BACKGROUND

The Hygiene Hypothesis (HH) attributes the dramatic increase in autoimmune and allergic diseases observed in recent decades in Western countries to the reduced exposure to diverse immunoregulatory infectious agents. This theory has since largely been supported by strong epidemiological and experimental evidence.

DISCUSSION

The analysis of these data along with the evolution of the Western world's microbiome enable us to obtain greater insight into microorganisms involved in the HH, as well as their regulatory mechanisms on the immune system. Helminthes and their derivatives were shown to have a protective role. Helminthes' broad immunomodulatory properties have already begun to be exploited in clinical trials of autoimmune diseases, including inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and type-1 diabetes.

SUMMARY

In this review, we will dissect the microbial actors thought to be involved in the HH as well as their immunomodulatory mechanisms as emphasized by experimental studies, with a particular attention on parasites. Thereafter, we will review the early clinical trials using helminthes' derivatives focusing on autoimmune diseases.

Helminthes and insects: maladies or therapies

By definition, parasites cause harm to their hosts. But, considerable evidence from ancient traditional medicine has supported the theory of using parasites and their products in treating many diseases. Maggots have been used successfully to treat chronic, long-standing, infected wounds which failed to respond to conventional treatment by many beneficial effects on the wound including debridement, disinfection, and healing enhancement. Maggots are also applied in forensic medicine to estimate time between the death and discovery of a corpse and in entomotoxicology involving the potential use of insects as alternative samples for detecting drugs and toxins in death investigations. Leeches are segmented invertebrates, famous by their blood-feeding habits and used in phlebotomy to treat various ailments since ancient times. Leech therapy is experiencing resurgence nowadays in health care principally in plastic and reconstructive surgery. Earthworms provide a source of medicinally useful products with potential antimicrobial, antiviral, and anticancer properties. Lumbrokinases are a group of fibrinolytic enzymes isolated and purified from earthworms capable of degrading plasminogen-rich and plasminogen-free fibrin and so can be used to treat various conditions associated with thrombotic diseases. Helminth infection has been proved to have therapeutic effects in both animal and human clinical trials with promising evidence in treating many allergic diseases and can block the induction of or reduce the severity of some autoimmune disorders as Crohn's disease or ulcerative colitis. What is more, venomous arthropods such as scorpions, bees, wasps, spiders, ants, centipedes, snail, beetles, and caterpillars. The venoms and toxins from these arthropods provide a promising source of natural bioactive compounds which can be employed in the development of new drugs to treat diseases as cancer. The possibility of using these active molecules in biotechnological processes can make these venoms and toxins a valuable and promising source of natural bioactive compounds. The therapeutic use of helminthes and insects will be of great value in biomedicine and further studies on insect toxins will contribute extensively to the development of Biomedical Sciences.

Induction of regulatory cells by helminth parasites: exploitation for the treatment of inflammatory diseases

Helminth parasites are highly successful pathogens, chronically infecting a quarter of the world's population, causing significant morbidity but rarely causing death. Protective immunity and expulsion of helminths is mediated by T-helper 2 (Th2) cells, type 2 (M2) macrophages, type 2 innate lymphoid cells, and eosinophils. Failure to mount these type 2 immune responses can result in immunopathology mediated by Th1 or Th17 cells. Helminths have evolved a wide variety of approaches for immune suppression, especially the generation of regulatory T cells and anti-inflammatory cytokines interleukin-10 and transforming growth factor-β. This is a very effective strategy for subverting protective immune responses to prolong their survival in the host but has the bystander effect of modulating immune responses to unrelated antigens. Epidemiological studies in humans have shown that infection with helminth parasites is associated with a low incidence of allergy/asthma and autoimmunity in developing countries. Experimental studies in mice have demonstrated that regulatory immune responses induced by helminth can suppress Th2 and Th1/Th17 responses that mediate allergy and autoimmunity, respectively. This has provided a rational explanation of the 'hygiene hypothesis' and has also led to the exploitation of helminths or their immunomodulatory products in the development of new immunosuppressive therapies for inflammatory diseases in humans.

Helminth parasites alter protection against Plasmodium infection

More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response.

Trichinella spiralis excretory-secretory products protect against polymicrobial sepsis by suppressing MyD88 via mannose receptor

Trichinella spiralis (T. spiralis) or its excretory-secretory products (TsES) protect hosts from autoimmune diseases, which depend on inducing host T helper (Th) 2 immune response and inhibiting inflammatory factors. Sepsis is a systemic inflammatory response syndrome (SIRS) evoked by infection. Little is known about the effects of helminths or their excretory-secretory products on sepsis. Here, we investigated the effects of TsES in a mice model of polymicrobial sepsis. TsES improved survival, reduced organ injury, and enhanced bacterial clearance in septic mice. To investigate the molecular mechanism, macrophages from septic patients or the control group were incubated with TsES. TsES reduced sepsis-inducing inflammatory cytokines mediated by Toll-like receptors (TLR) in vitro by suppressing TLR adaptor-transducer myeloid differentiation factor 88 (MyD88) and nuclear factor- (NF-)-κB. Furthermore, TsES upregulated mannose receptor (MR) expression during sepsis. MR blocking attenuated the effects of TsES on MyD88 and NF-κB expression. In vivo, MR RNAi reduced the survival rate of septic mice treated with TsES, suggesting that TsES-mediated protection against polymicrobial sepsis is dependent on MR. Thus, TsES administration might be a potential therapeutic strategy for treating sepsis.

Excretory/secretory products from Trichinella spiralis adult worms ameliorate DSS-induced colitis in mice

Background

Many evidences show the inverse correlation between helminth infection and allergic or autoimmune diseases. Identification and characterization of the active helminth-derived products responsible for the beneficial effects on allergic or inflammatory diseases will provide another feasible approach to treat these diseases.

Methods and Findings

Colitis was induced in C57BL/6 mice by giving 3% DSS orally for 7 days. During this period, the mice were treated daily with the excretory/secretory products from T. spiralis adult worms (AES) intraperitoneally. The severity of colitis was monitored by measuring body weight, stool consistency or bleeding, colon length and inflammation. To determine the T. spiralis AES product-induced immunological response, Th1, Th2, Th17 and regulatory cytokine profiles were measured in lymphocytes isolated from colon, mesenteric lymph nodes (MLN), and the spleen of treated mice. The CD4⁺ CD25⁺ FOXP3⁺ regulatory T cells (Tregs) were also measured in the spleens and MLN of treated mice. Mice treated with AES significantly ameliorated the severity of the DSS-induced colitis indicated by the reduced disease manifestations, improved macroscopic and microscopic inflammation correlated with the up-regulation of Treg response (increased regulatory cytokines IL-10, TGF-beta and regulatory T cells) and down-regulation of pro-inflammatory cytokines (IFN-gamma, IL-6 and IL-17) in the spleens, MLN and colon of treated mice.

Conclusions

Our results provide direct evidences that T. spiralis AES have a therapeutic potential for alleviating inflammatory colitis in mice. This effect is possibly mediated by the immunomodulation of regulatory T cells to produce regulatory and anti-inflammatory cytokines and inhibit pro-inflammatory cytokines.

Protection against allergic airway inflammation during the chronic and acute phases of Trichinella spiralis infection

BACKGROUND

Modulation of the host immune response by helminths has been reported to be essential for parasite survival and also to benefit the host by suppressing inflammatory diseases such as allergies. We have previously shown that excretory-secretory products of Trichinella spiralis muscle larvae have immunomodulatory properties and induce in vitro the expansion of CD4(+) CD25(+) FOXP3(+) Treg cells in a TGF-β-dependent manner.

OBJECTIVE

We aimed at determining the effect of the acute (intestinal) and the chronic (muscle) phase of T. spiralis infection on experimental allergic airway inflammation (EAAI) to Ovalbumin (OVA) and the involvement of Treg cells.

METHODS

The chronic phase was established before OVA-sensitization/challenge and the acute phase at two-time points, before and after OVA-sensitization. Mice were infected with 400 T. spiralis larvae and after euthanasia different pathological features of EAAI were measured. Adoptive transfer of CD4(+) T cells from Trichinella infected mice to OVA sensitized/challenged recipients was also performed.

RESULTS

We found that the chronic as well as the acute phase of Trichinella infection suppress EAAI as indicated by reduction in airway inflammation, OVA-specific IgE levels in sera, Th2-cytokine production and eosinophils in bronchoalveolar lavage. This protective effect was found to be stronger during the chronic phase and to be associated with increased numbers of splenic CD4(+) CD25(+) FOXP3(+) Treg cells with suppressive activity. Adoptive transfer of splenic CD4(+) T cells from chronically infected mice with elevated numbers of Treg cells resulted in partial protection against EAAI.

CONCLUSIONS AND CLINICAL RELEVANCE

These results demonstrate that the protective effect of T. spiralis on EAAI increases as infection progresses from the acute to the chronic phase. Here, Treg cells may play an essential role in the suppression of EAAI. Elucidating the mechanisms and molecular helminth structures responsible for this regulatory process is relevant to develop alternative tools for preventing or treating allergic asthma.

Trichinella spiralis shares epitopes with human autoantigens

Like other helminths, Trichinella spiralis has evolved strategies to allow it to survive in the host organism, including the expression of epitopes similar to those present in either expressed or hidden host antigens. To identify T. spiralis-derived antigens that are evolutionarily conserved in the parasite and its host and that could be responsible for its evasion of the host immune response, we examined the reactivity of six different types of autoantibodies to T. spiralis larvae from muscle. T. spiralis antigens that share epitopes with human autoantigens were identified by assessing the cross-reactivity of autoantibody-containing serum samples with T. spiralis antigens in the absence of specific anti-parasite antibodies. Of the 55 autoantibody-containing human serum samples that we analysed by immunohistological screening, 24 (43.6%) recognised T. spiralis muscle larvae structures such as the subcuticular region, the genital primordium or the midgut. Using Western blots, we demonstrated that the same sera reacted with 24 protein components of T. spiralis muscle larvae excretory-secretory L1 antigens. We found that the human autoantibodies predominantly bound antigens belonging to the TSL1 group; more specifically, the autoantibody-containing sera reacted most frequently with the 53-kDa component. Thus, this protein is a good candidate for further studies of the mechanisms of T. spiralis-mediated immunomodulation.

Application of dendritic cells stimulated with Trichinella spiralis excretory-secretory antigens alleviates experimental autoimmune encephalomyelitis

The parasitic nematode, Trichinella spiralis (T. spiralis), exerts an immunomodulatory effect on the host immune response through excretory-secretory products (ES L1) released from encysted muscle larvae. Our model of combined T. spiralis infection and experimental autoimmune encephalomyelitis (EAE) in Dark Agouti (DA) rats demonstrated a significant reduction in EAE severity in infected animals. Recently, we have created an immune status characteristic for the live infection by in vivo application of dendritic cells (DCs) stimulated with ES L1 products of T. spiralis muscle larvae. Moreover, these cells were able to ameliorate EAE when applied 7 days before EAE induction. ES L1-stimulated DCs increased production of IL-4, IL-10 and TGF-β, and decreased production of IFN-γ and IL-17, both at the systemic level and in target organs. A significant increase in the proportion of CD4+CD25+Foxp3+ T cells was found among spleen cells, and CNS infiltrates from DA rats treated with ES L1-stimulated DCs before EAE induction, compared to controls injected with unstimulated DCs. Regulatory T cells, together with elevated levels of IL-10 and TGF-β, are most likely involved in restraining the production of Th1 and Th17 cytokines responsible for autoimmunity and thus are responsible for the beneficial effect of ES L1-educated DCs on the course of EAE. Our results show that ES L1 antigen-stimulated DCs are able not only to provoke, but also to sustain anti-inflammatory and regulatory responses regardless of EAE induction, with subsequent amelioration of EAE, or even protection from the disease.

Helminths: Immunoregulation and Inflammatory Diseases-Which Side Are Trichinella spp. and Toxocara spp. on?

Macropathogens, such as multicellular helminths, are considered masters of immunoregulation due to their ability to escape host defense and establish chronic infections. Molecular crosstalk between the host and the parasite starts immediately after their encounter, which influences the course and development of both the innate and adaptive arms of the immune response. Helminths can modulate dendritic cells (DCs) function and induce immunosuppression which is mediated by a regulatory network that includes regulatory T (Treg) cells, regulatory B (Breg) cells, and alternatively activated macrophages (AAMs). In this way, helminths suppress and control both parasite-specific and unrelated immunopathology in the host such as Th1-mediated autoimmune and Th2-mediated allergic diseases. However, certain helminths favour the development or exacerbation of allergic responses. In this paper, the cell types that play an essential role in helminth-induced immunoregulation, the consequences for inflammatory diseases, and the contrasting effects of Toxocara and Trichinella infection on allergic manifestations are discussed.

Immunoregulation by Taenia crassiceps and its antigens

Taenia crassiceps is a cestode parasite of rodents (in its larval stage) and canids (in its adult stage) that can also parasitize immunocompromised humans. We have studied the immune response elicited by this helminth and its antigens in mice and human cells, and have discovered that they have a strong capacity to induce chronic Th2-type responses that are primarily characterized by high levels of Th2 cytokines, low proliferative responses in lymphocytes, an immature and LPS-tolerogenic profile in dendritic cells, the recruitment of myeloid-derived suppressor cells and, specially, alternatively activated macrophages. We also have utilized the immunoregulatory capabilities of this helminth to successfully modulate autoimmune responses and the outcome of other infectious diseases. In the present paper, we review the work of others and ourselves with regard to the immune response induced by T. crassiceps and its antigens, and we compare the advances in our understanding of this parasitic infection model with the knowledge that has been obtained from other selected models.

Helminth infections and host immune regulation

Helminth parasites infect almost one-third of the world's population, primarily in tropical regions. However, regions where helminth parasites are endemic record much lower prevalences of allergies and autoimmune diseases, suggesting that parasites may protect against immunopathological syndromes. Most helminth diseases are spectral in nature, with a large proportion of relatively asymptomatic cases and a subset of patients who develop severe pathologies. The maintenance of the asymptomatic state is now recognized as reflecting an immunoregulatory environment, which may be promoted by parasites, and involves multiple levels of host regulatory cells and cytokines; a breakdown of this regulation is observed in pathological disease. Currently, there is much interest in whether helminth-associated immune regulation may ameliorate allergy and autoimmunity, with investigations in both laboratory models and human trials. Understanding and exploiting the interactions between these parasites and the host regulatory network are therefore likely to highlight new strategies to control both infectious and immunological diseases.

Trichinella spiralis: shaping the immune response

The co-evolution of a wide range of helminth parasites and vertebrates represented a constant pressure on the host's immune system and a selective force for shaping the immune response. Modulation of the immune system by parasites is accomplished partly by dendritic cells. When exposed to helminth parasites or their products, dendritic cells do not become classically mature and are potent inducers of Th2 and regulatory responses. Treating animals with helminths (eggs, larvae, extracts) causes dampening or in some cases prevention of allergic or autoimmune diseases. Trichinella spiralis (T. spiralis) possess a capacity to retune the immune cell repertoire, acting as a moderator of the host response not only to itself but also to third party antigens. In this review, we will focus on the ability of T. spiralis-stimulated dendritic cells to polarize the immune response toward Th2 and regulatory mode in vitro and in vivo and also on the capacity of this parasite to modulate autoimmune disease--such as experimental autoimmune encephalomyelitis.

Heligmosomoides polygyrus: EAE remission is correlated with different systemic cytokine profiles provoked by L4 and adult nematodes

Primary exposure of mice to gastrointestinal nematode infection with Heligmosomoides polygyrus reduces inflammation in an experimental model of multiple sclerosis. In this study, we aimed to evaluate the ability of H. polygyrus L4 larvae and adults infection to reduce the symptoms of ongoing experimental autoimmune encephalomyelitis (EAE) in female C57Bl/6 mice. EAE was induced by myelin oligodendrocyte glycoprotein MOG(p35-55) and after 21 days mice were orally infected with 200 infective larvae (L3) of H. polygyrus. Reduction in EAE symptoms was observed from 2 days post infection and the symptoms were almost completely inhibited at 6 days post infection. This effect was associated with limited total protein content in the cerebrospinal fluid; CSF, and significant decreased pro-inflammatory IL-12p40 concentration and increased concentration of the regulatory cytokines IL-10, TGF-β and IL-6 in the CSF and in the serum. The reduction of EAE symptoms in the enteral phase was associated with higher IL-12p40 concentration in the CSF and very low concentrations of IL-17A and IL-2 in the serum. The fourth stage of gastrointestinal nematode can reverse systemic inflammation in animal models of multiple sclerosis by reducing IL-12 and promoting regulatory cytokines production. The mechanism induced by adult nematodes which sustained EAE inhibition can be provoked by regulatory mechanism connected with reduce IL-17A concentration.

Trichinella spiralis-secreted products modulate DC functionality and expand regulatory T cells in vitro

Helminths and their products can suppress the host immune response which may benefit parasite survival. Trichinella spiralis can establish chronic infections in a wide range of mammalian hosts including humans and mice. Here, we aim at studying the effect of T. spiralis muscle larvae excretory/secretory products (TspES) on the functionality of DC and T cell activation. We found that TspES suppress in vitro DC maturation induced by both S- and R-form lipopolysaccharide(LPS) from enterobacteria. Using different toll-like receptor (TLR) agonists, we show that the suppressive effect of TspES on DC maturation is restricted to TLR4. These helminth products also interfere with the expression of several genes related to the TLR-mediated signal transduction pathways. To investigate the effect of TspES on T cell activation, we used splenocytes derived from OVA-TCR transgenic D011.10 that were incubated with OVA and TspES-pulsed DC. Results indicate that the presence of TspES resulted in the expansion of CD4(+) CD25(+) Foxp3+ T cells. These regulatory T (Treg) cells were shown to have suppressive activity and to produce TGF-β. Together these results suggest that T. spiralis secretion products can suppress DC maturation and induce the expansion of functional Treg cells in vitro.

Soluble helminth products suppress clinical signs in murine experimental autoimmune encephalomyelitis and differentially modulate human dendritic cell activation

The increased incidence of auto-inflammatory and autoimmune diseases in the developed countries seems to be caused by an imbalance of the immune system due to the lack of proper regulation. Helminth parasites are well known modulators of the immune system and as such are of great interest for the treatment of these disorders. Clinical studies showed that administration of eggs of the pig nematode Trichuris suis to patients with inflammatory bowel disease reduces the disease severity. Here we demonstrate that treatment with soluble products from the nematodes T. suis and Trichinella spiralis induces significant suppression of symptoms in murine experimental autoimmune encephalomyelitis, a validated animal model for multiple sclerosis. These data show that infection with live nematodes is not a prerequisite for suppression of inflammation. To translate these results to the human system, the effects of soluble products of T. suis, T. spiralis and Schistosoma mansoni on the phenotype and function of human dendritic cells (DCs) were compared. Our data show that soluble products of T. suis, S. mansoni and T. spiralis suppress TNF-α and IL-12 secretion by TLR-activated human DCs, and that T. suis and S. mansoni, but not T. spiralis, strongly enhance expression of OX40L. Furthermore, helminth-primed human DCs differentially suppress the development of Th1 and/or Th17 cells. In conclusion, our data demonstrate that soluble helminth products have strong immunomodulatory capacities, but might exert their effects through different mechanisms. The suppressed secretion of pro-inflammatory cytokines together with an upregulation of OX40L expression on human DCs might contribute to achieve this modulation.

Helminth infections: therapeutic potential in autoimmune disorders

Knowledge of immunity enables us to predict that the reactions set in response to infection with helminth would prevent concomitant disease driven by an opposing spectrum of immune events. In another way, the immune response generated to combat the helminth infection could counteract the immunopathological reactions that drive autoimmune diseases. Rodent model systems recapitulate many aspects of human autoimmune diseases and have been enormously useful in defining mechanisms of immunopathology after infection. From this theoretical perspective, many researchers have proved that infection with a variety of helminth can ameliorate disease in murine model systems. Thus, helminth-evoked Th2 events were shown to improve disorders in which Th1 events predominated. This raised the question, 'Can this information be translated into therapies for autoimmune diseases in humans via actual infection, cell delivery or drug intervention?' In this review, we will present some experimental trails to treat autoimmune disorders through establishment of some parasitic infections.

Helminth infection does not reduce risk for chronic inflammatory disease in a population-based cohort study

BACKGROUND & AIMS

Parasitic helminth infections can suppress symptoms of allergy, type 1 diabetes, arthritis, and inflammatory bowel disease in animal models. We analyzed data from a large, population-based cohort study to determine whether common childhood enterobiasis protects against these diseases.

METHODS

We collected information on individual prescriptions filled for the drug mebendazole against Enterobius vermicularis for all children born in Denmark 1995-2008 from the National Register of Medicinal Product Statistics (n = 924,749; age 0-14 years); 132,383 of these children (14%) filled a prescription for mebendazole, 102,482 of the children (11%) had a household peer who was registered with a filled mebendazole prescription, and the remaining 689,884 children (75%) comprised the reference group. Children diagnosed with asthma, type 1 diabetes, juvenile arthritis, ulcerative colitis, or Crohn's disease were identified from the National Patient Registry. We used Poisson regression to estimate confounder-adjusted incidence rate ratios for first in- or outpatient hospital diagnosis of chronic inflammatory disease according to history of mebendazole treatment prescribed to children in the study.

RESULTS

Chronic inflammatory disease was diagnosed in 10,352 children during 6.4 million person-years of follow-up. The incidence rate ratios was 1.07 for asthma (95% confidence interval [CI]: 1.00-1.13), 1.05 for type 1 diabetes (95% CI: 0.79-1.12), 1.13 for juvenile arthritis (95% CI: 0.94-1.37), 0.77 for ulcerative colitis (95% CI: 0.41-1.46), and 1.44 for Crohn's disease (95% CI: 0.82-2.53). Results were not modified by number of treatments or age at treatment.

CONCLUSIONS

Based on a population-based analysis, enterobiasis does not reduce risk for asthma, type 1 diabetes, arthritis, or inflammatory bowel disease.

Alteration of helper T-cell related cytokine production in splenocytes during Trichinella spiralis infection

Infection by Trichinella spiralis takes place in two distinct phases: one is the intestinal phase and the other is the muscle phase. To evaluate alterations in cytokine production during a T. spiralis infection, we periodically assessed the cytokine production of splenocytes in mice after infection (AI). The levels of Th2-related cytokines immediately increased after the initiation of T. spiralis larval intestinal invasion (1 week AI). These early elevations in the Th2 response might be associated with the innate immune responses of intestine epithelial cells against T. spiralis larval invasion. IL-4 and IL-13 levels reached a peak prior to the initiation of nurse cell formation (2 weeks AI). Additionally, all Th17-related cytokines, except for IL-17, increased slightly until 2 weeks AI. However, expression levels for all of the Th2 and Th17-related cytokines began to decrease after the initiation of nurse cell formation and reached basal levels at 4 weeks AI, except for IL-5. At the same time, the CD4(+)CD25(+)Foxp3(+) T (regulatory T, T(reg)) cell population increased significantly in the spleen. Additionally, the number of cells in the peripheral lymph nodes increased. In conclusion, T. spiralis larva intestinal invasion induced the production of Th2 and Th17 cell-related cytokines, and the cytokines decreased with T(reg) cell-related cytokine.

Experimental autoimmune encephalomyelitis evolution was not modified by multiple infections with Strongyloides venezuelensis

According to the hygiene hypothesis, the increased incidence of allergic and autoimmune diseases in developed countries is mainly explained by the decreased contact between the human population and certain environmental agents as lactobacillus, mycobacteria and helminths. In this study, we evaluated the effect of multiple infections with Strongyloides venezuelensis on the development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Multiple infections before EAE induction were not able to change the evolution of the disease. No alterations were observed in weight loss, clinical score and inflammation intensity at the central nervous system. The presence of significant levels of parasite-specific IgG1 but not IgG2b suggested a Th2 polarization. However, the percentage and absolute number of CD4+CD25+Foxp3+ T cells were not changed, being their levels in the spleen and lymph nodes of infected rats comparable to the ones found in normal animals. These results suggest that a Th2-polarized response without concomitant expansion of Foxp3+ regulatory T cells was not able to modify EAE progression. Even though these results do not threaten the hygiene hypothesis, they suggest that this paradigm might be an oversimplification. They also emphasize the need of a study to compare the immunoregulatory ability associated with different helminth spp.

IL-23 modulated myelin-specific T cells induce EAE via an IFNγ driven, IL-17 independent pathway

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS) mediated by myelin-reactive CD4(+) T cells. An unresolved issue that has important clinical implications concerns the cytokines produced by myelin-reactive T cells that determine their pathogenicity. Initially, IL-12 polarized, IFNγ producing Th1 cells were thought to be essential for the development of EAE. More recently, IL-23 polarized, IL-17 producing Th17 cells have been highlighted as critical encephalitogenic effectors. There is growing evidence that parallel autoimmune pathways can result in common clinical and histopathological endpoints. In the current study, we describe a form of EAE induced by the transfer of IL-23 modulated CD4(+) T cells into IL-17 receptor (IL-17R) deficient hosts. We found that IL-23 stimulates myelin-reactive T cells to produce both IFNγ and IL-17. Surprisingly, in this model the development of EAE is IFNγ dependent. Our findings illustrate a novel mechanism by which IL-23 promotes encephalitogenicity and they further expand the spectrum of autoreactive T cells capable of mediating inflammatory demyelinating disease of the CNS.

Mechanisms of modulation of experimental autoimmune encephalomyelitis by chronic Trichinella spiralis infection in Dark Agouti rats

Trichinella spiralis is a helminth that provokes Th2 and anti-inflammatory type responses in an infected host. Our previous studies using Dark Agouti (DA) rats indicated that T. spiralis infection reduced experimental autoimmune encephalomyelitis (EAE) severity in rats. The aim of this study was to analyse the mechanisms underlying EAE suppression driven by T. spiralis infection. Reduced clinical and histological manifestations of the disease were accompanied by increased IL-4 and IL-10 production and decreased IFN-gamma and IL-17 production in draining lymph node cells. This indicates that T. spiralis infection successfully maintains a Th2 cytokine bias regardless of EAE induction. High IL-10 signifies parasite-induced anti-inflammatory and/or regulatory cell responses. Transfer of splenic T cell-enriched population of cells from T. spiralis-infected rats into EAE immunized rats caused amelioration of EAE and in some cases protection from disease development. This population of cells contained higher proportion of CD4(+) CD25(+) Foxp3(+) regulatory cells and produced high level of IL-10 when compared with uninfected rats.