Downregulation of the Syk Signaling Pathway in Intestinal Dendritic Cells Is Sufficient To Induce Dendritic Cells That Inhibit Colitis

The Roles of Various Immune Cell Populations in Immune Response against Helminths

Helminths are multicellular parasites that are a substantial problem for both human and veterinary medicine. According to estimates, 1.5 billion people suffer from their infection, resulting in decreased life quality and burdens for healthcare systems. On the other hand, these infections may alleviate autoimmune diseases and allergy symptoms. The immune system is programmed to combat infections; nevertheless, its effector mechanisms may result in immunopathologies and exacerbate clinical symptoms. This review summarizes the role of the immune response against worms, with an emphasis on the Th2 response, which is a hallmark of helminth infections. We characterize non-immune cells (enteric tuft cells-ETCs) responsible for detecting parasites, as well as the role of hematopoietic-derived cells (macrophages, basophils, eosinophils, neutrophils, innate lymphoid cells group 2-ILC2s, mast cells, T cells, and B cells) in initiating and sustaining the immune response, as well as the functions they play in granulomas. The aim of this paper is to review the existing knowledge regarding the immune response against helminths, to attempt to decipher the interactions between cells engaged in the response, and to indicate the gaps in the current knowledge.

Blockade of Syk modulates neutrophil immune-responses via the mTOR/RUBCNL-dependent autophagy pathway to alleviate intestinal inflammation in ulcerative colitis

Background

Ulcerative colitis (UC) is a progressive chronic inflammatory disorder. Neutrophils play a critical role in regulating intestinal mucosal homeostasis in UC. Spleen tyrosine kinase (Syk) is involved in several inflammatory diseases. Here, we evaluated the effects and underlying mechanisms of Syk on neutrophil immune-responses in UC.

Methods

Syk expression in the colonic tissues of patients with UC was determined using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry. Colonic biopsies from patients with UC were obtained for single-cell RNA-sequencing. Neutrophils isolated from peripheral blood were pre-treated with R788 (a Syk inhibitor) and gene differences were determined using RNA sequencing. Neutrophil functions were analyzed using qRT-PCR, flow cytometry, and Transwell assay. R788 was administered daily to mice with dextran sulfate sodium (DSS)-induced colitis to verify the effects of Syk on intestinal inflammation.

Results

Syk expression was increased in inflamed mucosa and neutrophils of patients with UC and positively correlated with disease activity. Pharmacological inhibition of Syk in neutrophils decreased the production of pro-inflammatory cytokines, chemokines, neutrophil extracellular traps, reactive oxygen species, and myeloperoxidase. Apoptosis and migration of neutrophils were suppressed by Syk blockade. Syk blockade ameliorated mucosal inflammation in DSS-induced murine colitis by inhibiting neutrophil-associated immune responses. Mechanistically, Syk regulated neutrophil immune-responses via the mammalian target of rapamycin kinase/rubicon-like autophagy enhancer-dependent autophagy pathway.

Conclusions

Our findings indicate that Syk facilitates specific neutrophil functional responses to mucosal inflammation in UC, and its inhibition ameliorates mucosal inflammation in DSS-induced murine colitis, suggesting its potential as a novel therapeutic target for UC treatment.

How to train your myeloid cells: a way forward for helminth vaccines?

Soil-transmitted helminths affect approximately 1.5 billion people worldwide. However, as no vaccine is currently available for humans, the current strategy for elimination as a public health problem relies on preventive chemotherapy. Despite more than 20 years of intense research effort, the development of human helminth vaccines (HHVs) has not yet come to fruition. Current vaccine development focuses on peptide antigens that trigger strong humoral immunity, with the goal of generating neutralizing antibodies against key parasite molecules. Notably, this approach aims to reduce the pathology of infection, not worm burden, with only partial protection observed in laboratory models. In addition to the typical translational hurdles that vaccines struggle to overcome, HHVs face several challenges (1): helminth infections have been associated with poor vaccine responses in endemic countries, probably due to the strong immunomodulation caused by these parasites, and (2) the target population displays pre-existing type 2 immune responses to helminth products, increasing the likelihood of adverse events such as allergy or anaphylaxis. We argue that such traditional vaccines are unlikely to be successful on their own and that, based on laboratory models, mucosal and cellular-based vaccines could be a way to move forward in the fight against helminth infection. Here, we review the evidence for the role of innate immune cells, specifically the myeloid compartment, in controlling helminth infections. We explore how the parasite may reprogram myeloid cells to avoid killing, notably using excretory/secretory (ES) proteins and extracellular vesicles (EVs). Finally, learning from the field of tuberculosis, we will discuss how anti-helminth innate memory could be harnessed in a mucosal-trained immunity-based vaccine.

Advances in Current Drugs and Formulations for the Management of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease with a complex pathophysiology. Treatment of AD remains challenging owing to the presence of a wide spectrum of clinical phenotypes and limited response to existing therapies. However, recent genetic, immunological, and pathophysiological insights into the disease mechanism resulted in the invention of novel therapeutic drug candidates. This review provides a comprehensive overview of current therapies and assesses various novel drug delivery strategies currently under clinical investigation. Further, this review majorly emphasizes on various topical treatments including emollient therapies, barrier repair agents, topical corticosteroids (TCS), phosphodiesterase 4 (PDE4) inhibitors, calcineurin inhibitors, and Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway inhibitors. It also discusses biological and systemic therapies, upcoming treatments based on ongoing clinical trials. Additionally, this review scrutinized the use of pharmaceutical inactive ingredients in the approved topical dosage forms for AD treatment.

Therapeutic strategy for rheumatoid arthritis by induction of myeloid-derived suppressor cells with high suppressive potential

Combination treatment using fingolimod (FTY720), an immunomodulator, and a pathogenic antigen prevents the progression of glucose-6-phosphate isomerase (GPI)_325-339-induced arthritis. In this study, we focused on myeloid-derived suppressor cells (MDSCs; CD11b⁺Gr-1⁺ cells) and investigated the effects of the combination treatment on these cells. DBA/1J mice with GPI_325-339-induced arthritis were treated using FTY720 and/or GPI_325-339 for five days. The expanded CD11b⁺Gr-1⁺ cell population and its inhibitory potential were examined. The percentage of CD369⁺CD11b⁺Gr-1⁺ cells effectively increased in the combination-treated mice. The inhibitory potential of CD369⁺CD11b⁺Gr-1⁺ cells was higher than that of cells not expressing CD369. Among bone marrow cells, the expression of CD369 in CD11b⁺Gr-1⁺ cells increased following stimulation with granulocyte-macrophage colony-stimulating factor, and the expression of CD11c increased accordingly. The increased CD11c expression indicated a decrease in the potential to suppress T cell proliferation based on the results of the suppression assay. The percentage of CD11c^-CD369⁺ cells in CD11b⁺Gr-1⁺ cells that were induced by the combination treatment also increased, and these cells tended to have a higher capacity to inhibit T cell proliferation. In conclusion, the combination treatment using FTY720 and the pathogenic antigen effectively induces MDSC, which demonstrates a high potential for suppressing T cell proliferation in the lymph nodes, thereby establishing an immune-tolerant state.

The Fibronectin-ILT3 Interaction Functions as a Stromal Checkpoint that Suppresses Myeloid Cells

Suppressive myeloid cells inhibit antitumor immunity by preventing T-cell responses. Immunoglobulin-like transcript 3 (ILT3; also known as LILRB4) is highly expressed on tumor-associated myeloid cells and promotes their suppressive phenotype. However, the ligand that engages ILT3 within the tumor microenvironment and renders tumor-associated myeloid cells suppressive is unknown. Using a screening approach, we identified fibronectin as a functional ligand for ILT3. The interaction of fibronectin with ILT3 polarized myeloid cells toward a suppressive state, and these effects were reversed with an ILT3-specific antibody that blocked the interaction of ILT3 with fibronectin. Furthermore, ex vivo treatment of human tumor explants with anti-ILT3 reprogrammed tumor-associated myeloid cells toward a stimulatory phenotype. Thus, the ILT3-fibronectin interaction represents a "stromal checkpoint" through which the extracellular matrix actively suppresses myeloid cells. By blocking this interaction, tumor-associated myeloid cells may acquire a stimulatory phenotype, potentially resulting in increased antitumor T-cell responses.

The ubiquitous role of spleen tyrosine kinase (Syk) in gut diseases: From mucosal immunity to targeted therapy

Spleen tyrosine kinase (Syk) is a cytoplasmic non-receptor protein tyrosine kinase expressed in a variety of cells and play crucial roles in signal transduction. Syk mediates downstream signaling by recruiting to the dually phosphorylated immunoreceptor tyrosine-based activation motifs (ITAMs) of the transmembrane adaptor molecule or the receptor chain itself. In gut diseases, Syk is observed to be expressed in intestinal epithelial cells, monocytes/macrophages, dendritic cells and mast cells. Activation of Syk in these cells can modulate intestinal mucosal immune response by promoting inflammatory cytokines and chemokines production, thus regulating gut homeostasis. Due to the restriction of specificity and selectivity for the development of Syk inhibitors, only a few such inhibitors are available in gut diseases, including intestinal ischemia/reperfusion damage, infectious disease, inflammatory bowel disease, etc. The promising outcomes of Syk inhibitors from both preclinical and clinical studies have shown to attenuate the progression of gut diseases thereby indicating a great potential in the development of Syk targeted therapy for treatment of gut diseases. This review depicts the characterization of Syk, summarizes the signal pathways of Syk, and discusses its potential targeted therapy for gut diseases.

Mining Helminths for Novel Therapeutics

Helminths are an emerging source of therapeutics for dysregulated inflammatory diseases. Excretory/secretory (ES) molecules, released during infection, are responsible for many of these immunomodulatory effects and are likely to have evolved as a means for parasite survival in the host. While the mechanisms of action of these molecules have not been fully defined, evidence demonstrates that they target various pathways in the immune response, ranging from initiation to effector cell modulation. These molecules are applied in controlling specific effector mechanisms of type 1 and type 2 immune responses. Recently, studies have further focused on their therapeutic potential in specific disease models. Here we review recent findings on ES molecule modulation of immune functions, specifically highlighting their clinical implications for future use in inflammatory disease therapeutics.

Gain-of-function variants in SYK cause immune dysregulation and systemic inflammation in humans and mice

Spleen tyrosine kinase (SYK) is a critical immune signaling molecule and therapeutic target. We identified damaging monoallelic SYK variants in six patients with immune deficiency, multi-organ inflammatory disease such as colitis, arthritis and dermatitis, and diffuse large B cell lymphomas. The SYK variants increased phosphorylation and enhanced downstream signaling, indicating gain of function. A knock-in (SYK-Ser544Tyr) mouse model of a patient variant (p.Ser550Tyr) recapitulated aspects of the human disease that could be partially treated with a SYK inhibitor or transplantation of bone marrow from wild-type mice. Our studies demonstrate that SYK gain-of-function variants result in a potentially treatable form of inflammatory disease.

CCL4-mediated targeting of spleen tyrosine kinase (Syk) inhibitor using nanoparticles alleviates inflammatory bowel disease

Inflammatory bowel disease (IBD) has emerged a global disease and the ascending incidence and prevalence is accompanied by elevated morbidity, mortality, and substantial healthcare system costs. However, the current typical one-size-fits-all therapeutic approach is suboptimal for a substantial proportion of patients due to the variability in the course of IBD and a considerable number of patients do not have positive response to the clinically approved drugs, so there is still a great, unmet demand for novel alternative therapeutic approaches. Spleen tyrosine kinase (Syk), a cytoplasmic nonreceptor protein tyrosine kinase, plays crucial roles in signal transduction and there are emerging data implicating that Syk participates in pathogenesis of several gut disorders, such as IBD. In this study, we observed the Syk expression in IBD patients and explored the effects of therapeutic Syk inhibition using small-molecule Syk inhibitor piceatannol in bone marrow-derived macrophages (BMDMs). In addition, due to the poor bioavailability and pharmacokinetics of small-molecule tyrosine kinase inhibitors and superiority of targeting nanoparticles-based drug delivery system, we herein prepared piceatannol-encapsulated poly(lactic-co-glycolic acid) nanoparticles that conjugated with chemokine C-C motif ligand 4 (P-NPs-C) and studied its therapeutic effects in vitro in BMDMs and in vivo in experimental colitis model. Our results indicated that in addition to alleviating colitis, oral administration of P-NPs-C promoted the restoration of intestinal barrier function and improved intestinal microflora dysbiosis, which represents a promising treatment for IBD.

Extracellular Vesicles Derived From Trichinella spiralis Muscle Larvae Ameliorate TNBS-Induced Colitis in Mice

Helminths are masters at modulating the host immune response through a wide variety of versatile mechanisms. These complex strategies facilitate parasite survival in the host and can also be exploited to prevent chronic immune disorders by minimizing excessive inflammation. Extracellular vesicles (EVs) are small membrane-bound structures secreted by helminths which mediate immune evasion during parasite infection. The goal of this study was to investigate the immunoregulatory properties of Trichinella spiralis EVs (Ts-EVs) in a murine model of colitis. We found that Ts-EVs significantly ameliorated 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice. Ts-EVs alleviated intestinal epithelium barrier damage, markedly reduced pro-inflammatory cytokine secretion and neutrophil infiltration, and upregulated immunoregulatory cytokine expression in colon tissue. Ts-EVs also modulated the adaptive immune response by influencing T-cell composition. The numbers of Th1 and Th17 cells in MLNs, as well as the expression levels of Th1/Th17-associated cytokines and transcription factors in colon were reduced. In contrast, Th2 and Treg cells were increased after Ts-EVs treatment. Furthermore, sequencing of EV-derived microRNAs (miRNAs) indicated that an array of miRNAs was involved in the regulation of the host immune response, including inflammation. These findings expand our knowledge of host-parasite interactions, and may help design novel and effective strategies to prevent parasite infections or to treat inflammatory diseases like IBD. Further studies are needed to identify the specific cargo molecules carried by Ts-EVs and to clarify their roles during T. spiralis infection.

JAK Inhibitors for Atopic Dermatitis: An Update

Atopic dermatitis (AD) is one of the most common inflammatory skin diseases. AD is driven by barrier dysfunction and abnormal immune activation of T helper (Th) 2, Th22, and varying degrees of Th1 and Th17 among various subtypes. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) and spleen tyrosine kinase (SYK) pathways are involved in signaling of several AD-related cytokines, such as IFN-γ, IL-4, IL-13, IL-31, IL-33, IL-23, IL-22, and IL-17, mediating downstream inflammation and barrier alterations. While AD is primarily Th2-driven, the clinical and molecular heterogeneity of AD endotypes highlights the unmet need for effective therapeutic options that target more than one immune axis and are safe for long-term use. The JAK inhibitors, which target different combinations of kinases, have overlapping but distinct mechanisms of action and safety profiles. Several topical and oral JAK inhibitors have been shown to decrease AD severity and symptoms. A review of the JAK and SYK inhibitors that are currently undergoing evaluation for efficacy and safety in the treatment of AD summarizes available data on a promising area of therapeutics and further elucidates the complex molecular interactions that drive AD.

Dendritic cells treated by Trichinella spiralis muscle larval excretory/secretory products alleviate TNBS-induced colitis in mice

BACKGROUND

Therapeutic potential of helminth have been shown to have a protective effect on immune-mediated diseases such as Crohn's disease (CD), which is associated with increased production of T helper cell type 1. However, helminth therapy is unacceptable to patients due to side-effects and the fear of parasites. As helminths regulate the cellular immune responses through innate cells such as dendritic cells (DCs), cellular immunotherapy has been considered a therapeutic option to treat CD.

METHODS

Bone marrow-dendritic cells were generated, enriched and treated with Trichinella spiralis muscle larval excretory/secretory products (Ts-MLES). DCs maturation was measured by flow cytometry and cytokine production of DCs were measured by ELISA. Colitis was generated by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) solution. For adoptive transfer, Ts-MLES treated-DCs injected intravenously 24 h prior to TNBS challenge. Disease activity index (DAI) including weight loss, diarrhea, and bloody stool were measured. Colon segments were stained with hematoxylin and eosin (H.E.) and periodic acid schiff (PAS) staining for histological damage scoring. The relative mRNA expression of cytokines in colon was analyzed by RT-PCR. Cytokine production in colon was measured by ELISA. Splenocytes were separated and cytokine profiles including Th1 (IFN-γ), Th2 (IL-4, IL-13), and Treg subsets (IL-10, TGF-β) were analyzed by flow cytometry.

RESULTS

Ts-MLES regulated the maturation and cytokine production of DCs. Ts-MLES -DC ameliorated the severity of the TNBS-induced colitis. In the colon and the spleen, Ts-MLES-DC decreased IFN-γ (Th1) significantly and increased Th2 (IL-4, IL-13)- and Treg (IL-10, TGF-β)- related cytokines.

CONCLUSIONS

Ts-MLES-DC ameliorated the severity of the TNBS-induced colitis through decreasing IFN-γ. Ts-MLES-DC skewed the Th1-mediated response toward the Th2 type and regulatory T cell response.

Exopolysaccharides from Cyanobacterium aponinum induce a regulatory dendritic cell phenotype and inhibit SYK and CLEC7A expression in dendritic cells, T cells and keratinocytes

Regular bathing in the Blue Lagoon has beneficial effects on psoriasis. Previously, we showed that exopolysaccharides (EPS-Ca) secreted by Cyanobacterium aponinum, a dominating organism in the Blue Lagoon, increased IL-10 secretion by human dendritic cells (DCs). In addition, co-culturing allogeneic CD4⁺ T cells with DCs matured in the presence of EPS-Ca increased differentiation of T cells into T regulatory cells at the cost of the disease inducing Th17 cells. In the present study, EPS-Ca increased the proportion of DCs expressing CD141, a surface molecule linked to regulatory DCs, and the CD141⁺ cells secreted more IL-10 than the CD141^- cells. EPS-Ca decreased T cell secretion of IL-17, IL-13 and IL-10 and the proportion of T cells expressing the activation marker CD69 that has also been linked to lymphocyte retention. In addition, EPS-Ca reduced keratinocyte secretion of CCL20 and CXCL10, chemokines implicated in recruitment of inflammatory cells. EPS-Ca decreased DC expression of Dectin-1/CLEC7A and SYK, keratinocyte expression of CLEC7A, SYK and CAMP (the gene for LL37), and T cell expression of phosphorylated Zap70. These results indicate that EPS-Ca may induce a regulatory phenotype of DCs, T cells that are less active/inflammatory and less prone to being retained in the skin, and keratinocytes that induce less recruitment of inflammatory cells to the skin and that these effects may be mediated by the effects of EPS-Ca on CLEC7A and SYK. Overall the results indicate that EPS-Ca may be involved in the beneficial effects psoriasis patients experience when bathing in the Blue Lagoon.

Macrophages treated with antigen from the tapeworm Hymenolepis diminuta condition CD25+ T cells to suppress colitis

Macrophages play central roles in immunity as early effectors and modulating adaptive immune reponses; we implicated macrophages in the anticolitic effect of infection with the tapeworm Hymenolepis diminuta. Here, gene arrays revealed that H. diminuta antigen (HdAg) evoked a program in murine macrophages distinct from that elicited by IL-4. Further, HdAg suppressed LPS-evoked release of TNF-α and IL-1β from macrophages via autocrine IL-10 signaling. In assessing the ability of macrophages treated in vitro with an extract of H. diminuta [M^(HdAg)] to affect disease, intravenous, but not peritoneal, injection of M^(HdAg) protected wild-type but not RAG1^-/- mice from dinitrobenzene sulphonic acid (DNBS)-induced colitis. Administration of splenic CD4⁺ T cells from in vitro cocultures with M^(HdAg), but not those cocultured with M^(IL-4) cells, inhibited DNBS-induced colitis; fractionation of the T-cell population indicated that the CD4⁺CD25⁺ T cells from cocultures with M^(HdAg) drove the suppression of DNBS-induced colitis. Use of IL-4^-/- or IL-10^-/- CD4⁺ T cells revealed that neither cytokine alone from the donor cells was essential for the anticolitic effect. These data illustrate that HdAg evokes a unique regulatory program in macrophages, identifies HdAg-evoked IL-10 suppression of macrophage activation, and reveals the ability of HdAg-treated macrophages to educate ( i.e., condition) and mobilize CD4⁺CD25⁺ T cells, which could be deployed to treat colonic inflammation.-Reyes, J. L., Lopes, F., Leung, G., Jayme, T. S., Matisz, C. E., Shute, A., Burkhard, R., Carneiro, M., Workentine, M. L., Wang, A., Petri, B., Beck, P. L., Geuking, M. B., McKay, D. M., Macrophages treated with antigen from the tapeworm Hymenolepis diminuta condition CD25⁺ T cells to suppress colitis.

The inflammatory function of human IgA

The prevailing concept regarding the immunological function of immunoglobulin A (IgA) is that it binds to and neutralizes pathogens to prevent infection at mucosal sites of the body. However, recently, it has become clear that in humans IgA is also able to actively contribute to the initiation of inflammation, both at mucosal and non-mucosal sites. This additional function of IgA is initiated by the formation of immune complexes, which trigger Fc alpha Receptor I (FcαRI) to synergize with various other receptors to amplify inflammatory responses. Recent findings have demonstrated that co-stimulation of FcαRI strongly affects pro-inflammatory cytokine production by various myeloid cells, including different dendritic cell subsets, macrophages, monocytes, and Kupffer cells. FcαRI-induced inflammation plays a crucial role in orchestrating human host defense against pathogens, as well as the generation of tissue-specific immunity. In addition, FcαRI-induced inflammation is suggested to be involved in the pathogenesis of various chronic inflammatory disorders, including inflammatory bowel disease, celiac disease, and rheumatoid arthritis. Combined, IgA-induced inflammation may be used to either promote inflammatory responses, e.g. in the context of cancer therapy, but may also provide new therapeutic targets to counteract chronic inflammation in the context of various chronic inflammatory disorders.

Immunomodulation by Helminths: Intracellular Pathways and Extracellular Vesicles

Helminth parasites are masters at manipulating host immune responses, using an array of sophisticated mechanisms. One of the major mechanisms enabling helminths to establish chronic infections is the targeting of pattern recognition receptors (PRRs) including toll-like receptors, C-type lectin receptors, and the inflammasome. Given the critical role of these receptors and their intracellular pathways in regulating innate inflammatory responses, and also directing adaptive immunity toward Th1 and Th2 responses, recognition of the pathways triggered and/or modulated by helminths and their products will provide detailed insights about how helminths are able to establish an immunoregulatory environment. However, helminths also target PRRs-independent mechanisms (and most likely other yet unknown mechanisms and pathways) underpinning the battery of different molecules helminths produce. Herein, the current knowledge on intracellular pathways in antigen presenting cells activated by helminth-derived biomolecules is reviewed. Furthermore, we discuss the importance of helminth-derived vesicles as a less-appreciated components released during infection, their role in activating these host intracellular pathways, and their implication in the development of new therapeutic approaches for inflammatory diseases and the possibility of designing a new generation of vaccines.

Trichinella spiralis Excretory-Secretory Products Induce Tolerogenic Properties in Human Dendritic Cells via Toll-Like Receptors 2 and 4

Trichinella spiralis, as well as its muscle larvae excretory–secretory products (ES L1), given either alone or via dendritic cells (DCs), induce a tolerogenic immune microenvironment in inbred rodents and successfully ameliorate experimental autoimmune encephalomyelitis. ES L1 directs the immunological balance away from T helper (Th)1, toward Th2 and regulatory responses by modulating DCs phenotype. The ultimate goal of our work is to find out if it is possible to translate knowledge obtained in animal model to humans and to generate human tolerogenic DCs suitable for therapy of autoimmune diseases through stimulation with ES L1. Here, the impact of ES L1 on the activation of human monocyte-derived DCs is explored for the first time. Under the influence of ES L1, DCs acquired tolerogenic (semi-matured) phenotype, characterized by low expression of HLA-DR, CD83, and CD86 as well as moderate expression of CD40, along with the unchanged production of interleukin (IL)-12 and elevated production of IL-10 and transforming growth factor (TGF)-β, compared to controls. The interaction with DCs involved toll-like receptors (TLR) 2 and 4, and this interaction was mainly responsible for the phenotypic and functional properties of ES L1-treated DCs. Importantly, ES L1 potentiated Th2 polarizing capacity of DCs, and impaired their allo-stimulatory and Th1/Th17 polarizing properties. Moreover, ES L1-treated DCs promoted the expansion of IL-10- and TGF-β- producing CD4⁺CD25^hiFoxp3^hi T cells in indolamine 2, 3 dioxygenase (IDO)-1-dependent manner and increased the suppressive potential of the primed T cell population. ES L1-treated DCs retained the tolerogenic properties, even after the challenge with different pro-inflammatory stimuli, including those acting via TLR3 and, especially TLR4. These results suggest that the induction of tolerogenic properties of DCs through stimulation with ES L1 could represent an innovative approach for the preparation of tolerogenic DC for treatment of inflammatory and autoimmune disorders.

Nematodes and human therapeutic trials for inflammatory disease

Helminth infections likely provide a protective influence against some immune-mediated and metabolic diseases because helminth infection dramatically decreased in developed countries shortly before the explosive rise in the prevalence of these diseases. The capacity of helminths to activate immune-regulatory circuits in their hosts and to modulate the composition of intestinal flora appears to be the mechanisms of protective action. Animal models of disease show that various helminth species prevent and/or block inflammation in various organs in a diverse range of diseases. Clinical trials have demonstrated that medicinal exposure to Trichuris suis or small numbers of Necator americanus is safe with minor, if any, reported adverse effects. This includes exposure of inflamed intestine to T. suis, asthmathic lung to N. americanus and in patients with atopy. Efficacy has been suggested in some small studies, but is absent in others. Factors that may have led to inconclusive results in some trials are discussed. To date, there have been no registered clinical trials using helminths to treat metabolic syndrome or its component conditions. However, the excellent safety profile of T. suis or N. americanus suggests that such studies should be possible.