IL-10-producing T regulatory type 1 cells and oral tolerance

Oral tolerance to dietary antigens and Foxp3+ regulatory T cells

Immune tolerance to foods develops in the intestine upon food ingestion and is essential to prevent IgE-mediated food allergy and gut inflammation. In homeostasis, the intestine is a tolerogenic environment that favors the formation of food-specific Foxp3+ regulatory T cells. A tolerogenic intestinal environment depends on colonization by diverse microbiota and exposure to solid foods at a critical period in early life. These early immune responses lead to the induction of antigen-specific Foxp3+ regulatory T cells in draining mesenteric lymph nodes. These peripherally induced regulatory cells circulate and seed the lamina propria of the gut, exerting suppressive function systemically and locally in the intestine. Successful establishment of a tolerogenic intestinal environment in early life sets the stage for oral tolerance to new antigens in adult life.

Immunotherapy with biodegradable nanoparticles encapsulating the oligosaccharide galactose-alpha-1,3-galactose enhance immune tolerance against alpha-gal sensitization in a murine model of alpha-gal syndrome

IgE antibodies against the mammalian oligosaccharide allergen galactose-α-1,3-galactose (αGal) can result in a severe allergic disease known as alpha-gal syndrome (AGS). This syndrome, acquired by tick bites that cause αGal sensitization, leads to allergic reactions after ingestion of non-primate mammalian meat and mammalian-derived products that contain αGal. Allergen-specific immunotherapies for this tickborne allergic syndrome are understudied, as are the immune mechanisms of allergic desensitization that induce clinical tolerance to αGal. Here, we reveal that prophylactic administration of αGal glycoprotein-containing nanoparticles to mice prior to tick protein-induced αGal IgE sensitization blunts the production of Th2 cytokines IL-4, IL-5, and IL-13 in an αGal-dependent manner. Furthermore, these effects correlated with suppressed production of αGal-specific IgE and hypersensitivity reactions, as measured by reduced basophil activation and histamine release and the systemic release of mast cell protease-1 (MCPT-1). Therapeutic administration of two doses of αGal-containing nanoparticles to mice sensitized to αGal had partial efficacy by reducing the Th2 cytokine production, αGal-specific IgE production, and MCPT-1 release without reducing basophil activation or histamine release. These data identify nanoparticles carrying encapsulated αGal glycoprotein as a potential strategy for augmenting αGal-specific immune tolerance and reveal diverse mechanisms by which αGal nanoparticles modify immune responses for established αGal-specific IgE-mediated allergic reactions.

Migratory CD103+CD11b+ cDC2s in Peyer's patches are critical for gut IgA responses following oral immunization

Induction and regulation of specific intestinal immunoglobulin (Ig)A responses critically depend on dendritic cell (DC) subsets and the T cells they activate in the Peyer's patches (PP). We found that oral immunization with cholera toxin (CT) as an adjuvant resulted in migration-dependent changes in the composition and localization of PP DC subsets with increased numbers of cluster of differentiation (CD)103- conventional DC (cDC)2s and lysozyme-expressing DC (LysoDCs) in the subepithelial dome and of CD103+ cDC2s that expressed CD101 in the T cell zones, while oral ovalbumin (OVA) tolerization was instead associated with greater accumulation of cDC1s and peripherally induced regulatory T cells (pTregs) in this area. Decreased IgA responses were observed after CT-adjuvanted immunization in huCD207DTA mice lacking CD103+ cDC2s, while oral OVA tolerization was inefficient in cDC1-deficient Batf3-/- mice. Using OVA transgenic T cell receptor CD4 T cell adoptive transfer models, we found that co-transferred endogenous wildtype CD4 T cells can hinder the induction of OVA-specific IgA responses through secretion of interleukin-10. CT could overcome this blocking effect, apparently through a modulating effect on pTregs while promoting an expansion of follicular helper T cells. The data support a model where cDC1-induced pTreg normally suppresses PP responses for any given antigen and where CT's oral adjuvanticity effect is dependent on promoting follicular helper T cell responses through induction of CD103+ cDC2s.

Causal relationship between immune cells and the risk of myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis: A Mendelian randomization study

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare inflammatory disease categorized as antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. The majority of patients are ANCA-positive, predominantly against myeloperoxidase (MPO). Previous studies have predominantly concentrated on the association between EGPA and neutrophils, but recent research has emphasized the role of lymphocytes in the development of EGPA. The objective of our research was to examine the causal association between immune cells and MPO + ANCA EGPA. A two-sample bidirectional Mendelian randomization (MR) analysis was performed, which included 159 MPO + ANCA EGPA cases and 6688 controls and utilized Genome-Wind Associaton Studies (GWAS) summary statistics of immune traits from approximately 3757 individuals, encompassing around 22 million single nucleotide polymorphisms (SNPs). Our findings revealed that 23 immunophenotypes were associated with MPO + ANCA EGPA. Furthermore, the reverse MR analysis showed that MPO + ANCA EGPA had significant causal effects on three immunophenotypes within the Treg panel. By integrating existing research, our study unveiled the contributions of Tregs, B cells, and monocytes to the development of EGPA. Subgroup analysis specifically examined the roles of lymphocyte subtypes, cytokines, and their surface molecules in the pathogenic mechanisms of the disease. This comprehensive approach provides a novel perspective on the biological mechanisms and early intervention strategies for MPO + ANCA EGPA by focusing on immune cells.

Oral mucosa immunity: ultimate strategy to stop spreading of pandemic viruses

Global pandemics are most likely initiated via zoonotic transmission to humans in which respiratory viruses infect airways with relevance to mucosal systems. Out of the known pandemics, five were initiated by respiratory viruses including current ongoing coronavirus disease 2019 (COVID-19). Striking progress in vaccine development and therapeutics has helped ameliorate the mortality and morbidity by infectious agents. Yet, organism replication and virus spread through mucosal tissues cannot be directly controlled by parenteral vaccines. A novel mitigation strategy is needed to elicit robust mucosal protection and broadly neutralizing activities to hamper virus entry mechanisms and inhibit transmission. This review focuses on the oral mucosa, which is a critical site of viral transmission and promising target to elicit sterile immunity. In addition to reviewing historic pandemics initiated by the zoonotic respiratory RNA viruses and the oral mucosal tissues, we discuss unique features of the oral immune responses. We address barriers and new prospects related to developing novel therapeutics to elicit protective immunity at the mucosal level to ultimately control transmission.

Biomarkers associated with persistence and severity of IgE-mediated food allergies: a systematic review

OBJECTIVE

The prevalence of food allergies (FA) has increased worldwide over the last few decades. Milk, eggs, and peanuts are among the most common allergens and can cause anaphylaxis. Therefore, we aimed to identify biomarkers that could predict the persistence and/or severity of IgE-mediated allergies to milk, eggs, and peanuts via a systematic review.

METHODS

This systematic review proceeded according to a protocol registered in the International Prospective Register of Systematic Reviews. Two independent authors extracted studies of interest from PubMed, SciELO, EMBASE, Scopus, and Ebsco databases and assessed their quality using the Newcastle-Ottawa Scale.

RESULTS

We selected 14 articles describing 1,398 patients. Among eight identified biomarkers, total IgE, specific IgE (sIgE), and IgG4 were the most often cited biomarkers of persistent allergies to milk, eggs, and peanuts. Skin prick tests, endpoint tests, and sIgE cutoff levels may predict positive responses to challenges with these foods. The basophil activation test is a biomarker for the severity and/or threshold of allergic reactions to milk and peanuts.

CONCLUSION

Only a few publications identified possible prognostic indicators of the persistence or severity of FA and outcomes of oral food challenges, indicating that more accessible biomarkers are needed to determine the likelihood of having a severe food allergic reaction.

Alteration of interleukin-10-producing Type 1 regulatory cells in autoimmune diseases

PURPOSE OF REVIEW

This review highlights findings describing the role of interleukin (IL)-10-producing Type 1 regulatory T (Tr1) cells in controlling autoimmune diseases and possible approaches to restore their function and number.

RECENT FINDINGS

Reduced frequency and/or function of cell subsets playing a role in Tr1 cell induction (e.g., DC-10 and Bregs), was found in patients with autoimmunity and may impact on Tr1 cell frequency.

SUMMARY

IL-10 is a pleiotropic cytokine with fundamental anti-inflammatory functions acting as negative regulator of immune responses. IL-10 is critically involved in the induction and functions of Tr1 cells, a subset of memory CD4+ T cells induced in the periphery to suppress immune responses to a variety of antigens (Ags), including self-, allogeneic, and dietary Ags. Alterations in IL-10-related pathways and/or in the frequency and activities of Tr1 cells have been associated to several autoimmune diseases. We will give an overview of the alterations of IL-10 and IL-10-producing Tr1 cells in Multiple Sclerosis, Type 1 Diabetes, and Celiac Disease, in which similarities in the role of these tolerogenic mechanisms are present. Current and future approaches to overcome Tr1 cell defects and restore tolerance in these diseases will also be discussed.

Immune tolerance of food is mediated by layers of CD4+ T cell dysfunction

Gastrointestinal health depends on the adaptive immune system tolerating the foreign proteins in food^1,2. This tolerance is paradoxical because the immune system normally attacks foreign substances by generating inflammation. Here we addressed this conundrum by using a sensitive cell enrichment method to show that polyclonal CD4⁺ T cells responded to food peptides, including a natural one from gliadin, by proliferating weakly in secondary lymphoid organs of the gut-liver axis owing to the action of regulatory T cells. A few food-specific T cells then differentiated into T follicular helper cells that promoted a weak antibody response. Most cells in the expanded population, however, lacked canonical T helper lineage markers and fell into five subsets dominated by naive-like or T follicular helper-like anergic cells with limited capacity to form inflammatory T helper 1 cells. Eventually, many of the T helper lineage-negative cells became regulatory T cells themselves through an interleukin-2-dependent mechanism. Our results indicate that exposure to food antigens causes cognate CD4⁺ naive T cells to form a complex set of noncanonical hyporesponsive T helper cell subsets that lack the inflammatory functions needed to cause gut pathology and yet have the potential to produce regulatory T cells that may suppress it.

Immutol regulates CD4+Tregs, CD8+Tregs and pDCs via IDO signaling pathway to induce immune tolerance in rat heart allograft transplant

Indoleamine 2,3-dioxygenase (IDO) can promote tryptophan metabolism to kynurenine and modulate regulatory T cells (Tregs), thereby maintains lower efficiency to induce tolerance. Our aim is to investigate the mechanism of tolerance induction by a IDO metabolite named Immutol.

METHODS

We established rat heterotopic heart transplantation models and treated them with Immutol, cyclosporine A (CsA) and 1-methyl-DL-tryptophan (1-MT) in vivo. The drugs were administered via gavage to all but the control group one day before surgery. CsA was gavaged continually for 20 days and Immutol for 60 days; after withdrawal of the drugs, the recipients were observed for at least 10 months. Immune cells were analyzed by flow cytometry. The IDO signaling pathway was evaluated by Western blotting, RT-PCR and immunochemical staining. Enzyme-linked immunosorbent assays (ELISAs) were used to detect changes in cytokines.

RESULTS

CsA or Immutol alone prolonged survival but did not induce tolerance after withdrawal. Immutol+CsA inhibited acute rejection, and the grafts survived more than 400 d, with tolerance detected in most rats (13/15). Increased protein IDO and kynurenine could regulate the accumulation of CD4⁺Tregs, CD8⁺Tregs and pDC to induce immune tolerance. I-MT specifically blocked IDO, weakened the expression of IDO and kynurenine, and produced grafts rejection. Additionally, Tregs could down-regulate immune responses through production of the immunosuppressive cytokines IL-10 and TGF-beta, thus induce immune tolerance. CD8⁺ Tregs produce IFN-γ, and tolerance is dependent on both IFN-γ and IDO.

CONCLUSION

Immutol combined with CsA can control acute rejection and induce tolerance in rats with cardiac allografts after withdrawal. Immutol may become a novel drug for future clinical use.

Plasmacytoid dendritic cells and their therapeutic activity in cancer

In the last decade several studies provided evidence that plasmacytoid dendritic cells (pDCs) infiltrate human neoplasms with poor prognosis. However, the role of tumor-associated pDCs remains controversial. Various studies indicate that pDCs play an immuno-suppressive role and facilitate tumor progression in both animal models and humans. In contrast, others found that the presence of activated tumor-associated pDCs results in tumor regression in mice. Given these findings, understanding pDC function in tumor biology is an important necessity and may pave the way for novel therapeutic strategies to fight malignancies.

Gut Microbiota and Liver Interaction through Immune System Cross-Talk: A Comprehensive Review at the Time of the SARS-CoV-2 Pandemic

Background and aims: The gut microbiota is a complex ecosystem containing bacteria, viruses, fungi, yeasts and other single-celled organisms. It is involved in the development and maintenance of both innate and systemic immunity of the body. Emerging evidence has shown its role in liver diseases through the immune system cross-talk. We review herein literature data regarding the triangular interaction between gut microbiota, immune system and liver in health and disease. Methods: We conducted a search on the main medical databases for original articles, reviews, meta-analyses, randomized clinical trials and case series using the following keywords and acronyms and their associations: gut microbiota, microbiome, gut virome, immunity, gastrointestinal-associated lymphoid tissue (GALT), non-alcoholic fatty liver disease (NAFLD), non-alcoholic steato-hepatitis (NASH), alcoholic liver disease, liver cirrhosis, hepatocellular carcinoma. Results: The gut microbiota consists of microorganisms that educate our systemic immunity through GALT and non-GALT interactions. The latter maintain health but are also involved in the pathophysiology and in the outcome of several liver diseases, particularly those with metabolic, toxic or immune-mediated etiology. In this context, gut virome has an emerging role in liver diseases and needs to be further investigated, especially due to the link reported between severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection and hepatic dysfunctions. Conclusions: Changes in gut microbiota composition and alterations in the immune system response are involved in the pathogenesis of metabolic and immune-mediated liver diseases.

Feeding Buttermilk-Derived Choline Forms During Gestation and Lactation Modulates Ex Vivo T-Cell Response in Rat Dams

BACKGROUND

Buttermilk contains a mixture of choline forms; it is high in phosphatidylcholine (PC) and sphingomyelin (SM), which could have an impact on immune system development and function.

OBJECTIVES

We aimed to determine the effect of feeding buttermilk-derived choline forms during pregnancy and lactation on maternal immune function.

METHODS

Sprague Dawley dams (n = 8 per diet) were randomly assigned midway through pregnancy (10 d of gestation) to 1 of 3 experimental diets, containing 1.7 g/kg choline: control [100% free choline (FC)]; buttermilk [37% PC, 34% SM, 17% glycerophosphocholine (GPC), 7% FC, 5% phosphocholine]; or placebo (50% PC, 25% FC, 25% GPC). Dams consumed the same diet until the end of the lactation period (21 d after parturition). Cell phenotypes and cytokine production by mitogen-stimulated splenocytes were measured and compared using 1-factor ANOVA test in order to asses the effect of diet on immune fuction of lactating dams (main outcome).

RESULTS

After ConA stimulation, splenocytes from dams in the buttermilk group produced more IL-2 (30%), TNF-α (30%), and IFN-γ (42%) compared with both the placebo and control diets. Placebo-fed dams had a higher proportion of CD8+ cells expressing CD152+ (22%) in spleen, and splenocytes from dams that were fed the buttermilk and the placebo diets produced about 50% and 53% more IL-10 after LPS and OVA stimulation, respectively, compared with the control group.

CONCLUSIONS

Feeding buttermilk-derived choline forms during pregnancy and lactation had a beneficial impact on the immune system of Sprague Dawley rat dams, especially on T-cell function.

Interleukin 10: the critical role of a pleiotropic cytokine in food allergy

Despite advances in research, the pathophysiology of food allergy has not yet been fully elucidated. IL-10 has both a pro- and anti-inflammatory effect on the development of food allergy and in order to understand its different immune-modulatory effects the factors that influence the inflammatory microenvironment need to be taken into account. Specific single nucleotide polymorphisms of the IL-10 gene seem to confer an increased risk of developing food allergy, but to date there is a substantial lack of genome- wide association studies regarding the genetic and epigenetic underpinnings of the disease. Special interest has been drawn to the development of allergen-specific regulatory CD4+CD25+ T-cells secreting IL-10 in the immunotherapy of allergic diseases. In addition, a distinct population of human tolerogenic dendritic cells (DC), DC-10 seems to hold great potential and could potentially serve as a therapeutic tool to improve the management of food allergy.

Mesenchymal Stem Cells Extract (MSCsE)-Based Therapy Alleviates Xerostomia and Keratoconjunctivitis Sicca in Sjogren's Syndrome-Like Disease

Sjogren’s syndrome (SS) is an autoimmune disease that manifests primarily in salivary and lacrimal glands leading to dry mouth and eyes. Unfortunately, there is no cure for SS due to its complex etiopathogenesis. Mesenchymal stem cells (MSCs) were successfully tested for SS, but some risks and limitations remained for their clinical use. This study combined cell- and biologic-based therapies by utilizing the MSCs extract (MSCsE) to treat SS-like disease in NOD mice. We found that MSCsE and MSCs therapies were successful and comparable in preserving salivary and lacrimal glands function in NOD mice when compared to control group. Cells positive for AQP5, AQP4, α-SMA, CK5, and c-Kit were preserved. Gene expression of AQP5, EGF, FGF2, BMP7, LYZ1 and IL-10 were upregulated, and downregulated for TNF-α, TGF-β1, MMP2, CASP3, and IL-1β. The proliferation rate of the glands and serum levels of EGF were also higher. Cornea integrity and epithelial thickness were maintained due to tear flow rate preservation. Peripheral tolerance was re-established, as indicated by lower lymphocytic infiltration and anti-SS-A antibodies, less BAFF secretion, higher serum IL-10 levels and FoxP3⁺ T_reg cells, and selective inhibition of B220⁺ B cells. These promising results opened new venues for a safer and more convenient combined biologic- and cell-based therapy.

A comprehensive understanding of the gut mucosal immune system in allergic inflammation

Despite its direct exposure to huge amounts of microorganisms and foreign and dietary antigens, the gut mucosa maintains intestinal homeostasis by utilizing the mucosal immune system. The gut mucosal immune system protects the host from the invasion of infectious pathogens and eliminates harmful non-self antigens, but it allows the cohabitation of commensal bacteria in the gut and the entry of dietary non-self antigens into the body via the mucosal surface. These physiological and immunological activities are regulated by the ingenious gut mucosal immune network, comprising such features as gut-associated lymphoid tissue, mucosal immune cells, cytokines, chemokines, antimicrobial peptides, secretory IgA, and commensal bacteria. The gut mucosal immune network keeps a fine tuned balance between active immunity (against pathogens and harmful non-self antigens) and immune tolerance (to commensal microbiota and dietary antigens), thus maintaining intestinal healthy homeostasis. Disruption of gut homeostasis results in persistent or severe gastrointestinal infection, inflammatory bowel disease, or allergic inflammation. In this review, we comprehensively introduce current knowledge of the gut mucosal immune system, focusing on its interaction with allergic inflammation.

Directed Differentiation of Human Induced Pluripotent Stem Cells into Dendritic Cells Displaying Tolerogenic Properties and Resembling the CD141+ Subset

The advent of induced pluripotent stem cells (iPSCs) has begun to revolutionize cell therapy by providing a convenient source of rare cell types not normally available from patients in sufficient numbers for therapeutic purposes. In particular, the development of protocols for the differentiation of populations of leukocytes as diverse as naïve T cells, macrophages, and natural killer cells provides opportunities for their scale-up and quality control prior to administration. One population of leukocytes whose therapeutic potential has yet to be explored is the subset of conventional dendritic cells (DCs) defined by their surface expression of CD141. While these cells stimulate cytotoxic T cells in response to inflammation through the cross-presentation of viral and tumor-associated antigens in an MHC class I-restricted manner, under steady-state conditions CD141⁺ DCs resident in interstitial tissues are focused on the maintenance of homeostasis through the induction of tolerance to local antigens. Here, we describe protocols for the directed differentiation of human iPSCs into a mixed population of CD11c⁺ DCs through the spontaneous formation of embryoid bodies and exposure to a cocktail of growth factors, the scheduled withdrawal of which serves to guide the process of differentiation. Furthermore, we describe the enrichment of DCs expressing CD141 through depletion of CD1c⁺ cells, thereby obtaining a population of “untouched” DCs unaffected by cross-linking of surface CD141. The resulting cells display characteristic phagocytic and endocytic capacity and acquire an immunostimulatory phenotype following exposure to inflammatory cytokines and toll-like receptor agonists. Nevertheless, under steady-state conditions, these cells share some of the tolerogenic properties of tissue-resident CD141⁺ DCs, which may be further reinforced by exposure to a range of pharmacological agents including interleukin-10, rapamycin, dexamethasone, and 1α,25-dihydoxyvitamin D₃. Our protocols therefore provide access to a novel source of DCs analogous to the CD141⁺ subset under steady-state conditions in vivo and may, therefore, find utility in the treatment of a range of disease states requiring the establishment of immunological tolerance.

The Interleukin (IL)-23/T helper (Th)17 Axis in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

T helper (Th)17 cells are responsible for host defense against fungi and certain extracellular bacteria but have also been reported to play a role in a variety of autoimmune diseases. Th17 cells respond to environmental cues, are very plastic, and might also be involved in tissue homeostasis and regeneration. The imprinting of pathogenic properties in Th17 cells in autoimmunity seems highly dependent on interleukin (IL)-23. Since Th17 cells were first described in experimental autoimmune encephalomyelitis, they have been suggested to also promote tissue damage in multiple sclerosis (MS). Indeed, some studies linked Th17 cells to disease severity in MS, and the efficacy of anti-IL-17A therapy in MS supported this idea. In this review, we will summarize molecular features of Th17 cells and discuss the evidence for their function in experimental models of autoimmune diseases and MS.

Molecular and cellular mechanisms of food allergy and food tolerance

Ingestion of innocuous antigens, including food proteins, normally results in local and systemic immune nonresponsiveness in a process termed oral tolerance. Oral tolerance to food proteins is likely to be intimately linked to mechanisms that are responsible for gastrointestinal tolerance to large numbers of commensal microbes. Here we review our current understanding of the immune mechanisms responsible for oral tolerance and how perturbations in these mechanisms might promote the loss of oral tolerance and development of food allergies. Roles for the commensal microbiome in promoting oral tolerance and the association of intestinal dysbiosis with food allergy are discussed. Growing evidence supports cutaneous sensitization to food antigens as one possible mechanism leading to the failure to develop or loss of oral tolerance. A goal of immunotherapy for food allergies is to induce sustained desensitization or even true long-term oral tolerance to food allergens through mechanisms that might in part overlap with those associated with the development of natural oral tolerance.

Enhancement of Oral Tolerance Induction in DO11.10 Mice by Lactobacillus gasseri OLL2809 via Increase of Effector Regulatory T Cells

Food allergy is a serious problem for infants and young children. Induction of antigen-specific oral tolerance is one therapeutic strategy. Enhancement of oral tolerance induction by diet is a promising strategy to prevent food allergy in infants. Thus, in this study, we evaluate the effect of probiotic Lactobacillus gasseri OLL2809 (LG2809) on oral tolerance induction in a mouse model. The degree of oral tolerance induction was evaluated by measuring the proliferation and level of IL-2 production of splenic CD4⁺ T cells from DO11.10 mice fed ovalbumin (OVA) alone or OVA with LG2809. Oral administration of LG2809 significantly decreased the rate of proliferation and IL-2 production by CD4⁺ T cells from OVA-fed mice. LG2809 increased a ratio of CD4⁺ T-cell population, producing high levels of IL-10 and having strong suppressive activity. Moreover, LG2809 increased a ratio of plasmacytoid dendritic cells (pDCs) among the lamina propria (LP) in small intestine. When used as antigen presenting cells to naïve CD4⁺ T cells from DO11.10 mice, LP cells from BALB/c mice fed LG2809 induced higher IL-10 production and stronger suppressive activity than those from non-treated mice. These results suggest that oral administration of LG2809 increases the population of pDCs in the LP, resulting in the enhancement of oral tolerance induction by increasing the ratio of effector regulatory T cells. LG2809 could, therefore, act as a potent immunomodulator to prevent food allergies by promoting oral tolerance.

Microbiota, immunity and the liver

The gut harbors a complex community of over 100 trillion microbial cells known to exist in symbiotic harmony with the host influencing human physiology, metabolism, nutrition and immune function. It is now widely accepted that perturbations of this close partnership results in the pathogenesis of several major diseases with increasing evidence highlighting their role outside of the intestinal tract. The intimate proximity and circulatory loop of the liver and the gut has attracted significant attention regarding the role of the microbiota in the development and progression of liver disease. Here we give an overview of the interaction between the microbiota and the immune system and focus on their convincing role in both the propagation and treatment of liver disease.

Intranasal immunization with heat shock protein 60 induces CD4(+) CD25(+) GARP(+) and type 1 regulatory T cells and inhibits early atherosclerosis

Atherosclerosis is an autoimmune inflammatory disease involving both innate and adaptive immune mechanisms. Immune tolerance induction may have therapeutic potential for the suppression of atherosclerosis. Current interest is directed towards mucosal tolerance induction, especially nasal tolerance. Previous studies have shown that heat shock protein 60 (HSP60) is recognized as an important autoantigen in atherosclerosis, and nasal or oral HSP60 can induce tolerance and ameliorate atherosclerosis by inducing several subsets of regulatory T cells (Tregs ) such as latency-associated peptide (LAP)(+) and forkhead box transcription factor 3 (FoxP3)(+) Tregs. However, little is known regarding the detailed mechanisms of nasal tolerance. Here, we again investigated the impact of nasal HSP60 on atherosclerosis and the mechanisms underlying the anti-atherosclerosis responses. We found that nasal HSP60 caused a significant 33·6% reduction in plaque size at the aortic root in the early stages of atherosclerosis (P < 0·001). Notably, a significant increase in activated CD4(+) CD25(+) glycoprotein A repetitions predominant (GARP)(+) Tregs, type 1 Tregs (Tr1 cells), and CD4(+) CD25(+) FoxP3(+) Tregs, as well as a marked decrease in the numbers of type 1 and 17 T helper cells was detected in the spleens and cervical lymph nodes of HSP60-treated mice. Moreover, nasal HSP60 increases the production of transforming growth factor (TGF)-β and interleukin (IL)-10 and decreases the secretion of IFN-γ and IL-17. Interestingly, the atheroprotective role of nasal HSP60 treatment was abrogated partly by the neutralization of IL-10. Our findings show that nasal administration of HSP60 can attenuate atherosclerotic formation by inducing GARP(+) Tregs, Tr1 cells and FoxP3(+) Tregs, and that these Tregs maintain immune homeostasis by secreting IL-10 and TGF-β.

Imbalance of serum IL-10 and TGF-β in patients with pollen food syndrome

BACKGROUND

Pollen food syndrome is one of the main causes of food allergies in adults. However, the intrinsic immunological mechanisms remain unclear.

METHODS

Forty pollinosis sufferers [23 with a food allergy (PSFA) and 17 without a food allergy (PS)] and 17 non-atopic healthy controls were included in this study. The PSFA group was subdivided into an oral allergy syndrome group, a systemic reaction group, and an anaphylactic reaction group according to their symptoms after eating the suspected foods. Serum IL-10 and TGF-β levels of all participants were determined by ELISA. Clinical characteristics of the patients were also evaluated.

RESULTS

There were no significant differences in age, sex, pollen-associated symptoms, duration of respiratory disease, and positive parental history of atopy between the PSFA and PS groups. Compared to healthy controls, serum IL-10 levels of both the PSFA group and PS group were significantly lower (p≤0.01), but TGF β levels were significantly higher in the PSFA group (35.3±5.6ng/ml vs. 31.2±6.6ng/ml, respectively; p=0.037). Within the PSFA group, IL-10 levels in the anaphylactic reaction subgroup were significantly lower compared to oral allergy syndrome subgroup (1.87±0.47pg/ml vs. 1.40±0.30pg/ml, respectively; p=0.027). More severe food allergy symptoms were associated with lower serum IL-10 levels. In contrast, the highest serum levels of TGF-β were found in patients from the anaphylactic reaction subgroup.

CONCLUSIONS

With the exception of a defect in regulatory cells represented by the reduction of IL-10, other potential immunological mechanisms (e.g., Th17 or IL-23 together with TGF-β) may be involved in the development of pollen food syndrome.

Atopy and the gastrointestinal tract--a review of a common association in unexplained gastrointestinal disease

In addition to diseases conventionally associated with atopy there is increasing recognition that atopy is also linked to a spectrum of gastrointestinal (GI) manifestations, including food allergy, primary eosinophilic GI disease, functional gastrointestinal disorders, gluten interactions, gastroesophageal reflux disease and inflammatory bowel disease. These associations may be underpinned by shared genetic susceptibilities, initiation of related immune pathways and common patterns of exposure to environmental cues, including allergen/pathogen encounters and variations in the composition of the intestinal microbiota. Further scrutiny of GI diseases with prominent allergic-type immune responses may yet redefine treatment paradigms for these common and important atopy-associated diseases. Looking forward, interventions by manipulation of the microbiota or host immune responses hold promise, but there is still room for further exploration of this novel field of host susceptibility, host-microbe interactions and atopy-associated GI diseases.

Cholangiocarcinoma with respect to IgG4 Reaction

IgG4 reactions marked by infiltration of IgG4-positive plasma cells in affected organs occur in cancer patients and in patients with IgG4-related diseases. Extrahepatic cholangiocarcinomas including gall bladder cancer are often accompanied by significant IgG4 reactions; these reactions show a negative correlation with CD8-positive cytotoxic T cells, suggesting that the evasion of immune surveillance is associated with cytotoxic T cells. The regulatory cytokine IL-10 may induce IgG4-positive plasma cell differentiation or promote B cell switching to IgG4 in the presence of IL-4. Cholangiocarcinoma cells may function as nonprofessional antigen presenting cells that indirectly induce IgG4 reactions via the IL-10-producing cells and/or these may act as Foxp3-positive and IL-10-producing cells that directly induce IgG4 reactions. Moreover, IgG4-related disease is a high-risk factor for cancer development; IgG4-related sclerosing cholangitis (IgG4-SC) cases associated with cholangiocarcinoma or its precursor lesion biliary intraepithelial neoplasia (BilIN) have been reported. IgG4-positive cell infiltration is an important finding of IgG4-SC but is not a histological hallmark of IgG4-SC. For the diagnosis of IgG4-SC, its differentiation from cholangiocarcinoma remains important.

Interleukin 10 (IL10) and transforming growth factor β1 (TGFβ1) gene polymorphisms in persistent IgE-mediated cow's milk allergy

OBJECTIVES

The aim of this cross-sectional study was to evaluate whether interleukin 10 (IL10) and transforming growth factor β1 (TGFβ1) gene polymorphisms were associated with persistent IgE-mediated cow's milk allergy in 50 Brazilian children. The diagnostic criteria were anaphylaxis triggered by cow's milk or a positive double-blind, placebo-controlled food challenge. Tolerance was defined as the absence of a clinical response to a double-blind, placebo-controlled food challenge or cow's milk exposure.

METHOD

The genomic DNA of the 50 patients and 224 healthy controls (HCs) was used to investigate five IL10 gene polymorphisms (-3575A/T, -2849A/G, -2763A/C, -1082G/A, -592C/A) and one TGFβ1 polymorphism (-509C/T).

RESULTS

Among the five IL10 polymorphisms analyzed, homozygosis for the G allele at the -1082 position was significantly higher in the patients compared with the healthy controls (p=0.027) and in the persistent cow's milk allergy group compared with the healthy controls (p=0.001).

CONCLUSIONS

Homozygosis for the G allele at the IL10 -1082G/A polymorphism is associated with the persistent form of cow's milk allergy.

Ovariectomized OVA-sensitized mice display increased frequency of CD4(+)Foxp3(+) T regulatory cells in the periphery

It is well established that female sex hormones have a pivotal role in inflammation. For instance, our group has previously reported that estradiol has proinflammatory actions during allergic lung response in animal models. Based on these findings, we have decided to further investigate whether T regulatory cells are affected by female sex hormones absence after ovariectomy. We evaluated by flow cytometry the frequencies of CD4⁺Foxp3⁺ T regulatory cells (Tregs) in central and peripheral lymphoid organs, such as the thymus, spleen and lymph nodes. Moreover, we have also used the murine model of allergic lung inflammation a to evaluate how female sex hormones would affect the immune response in vivo. To address that, ovariectomized or sham operated female Balb/c mice were sensitized or not with ovalbumin 7 and 14 days later and subsequently challenged twice by aerosolized ovalbumin on day 21. Besides the frequency of CD4⁺Foxp3⁺ T regulatory cells, we also measured the cytokines IL-4, IL-5, IL-10, IL-13 and IL-17 in the bronchoalveolar lavage from lungs of ovalbumine challenged groups. Our results demonstrate that the absence of female sex hormones after ovariectomy is able to increase the frequency of Tregs in the periphery. As we did not observe differences in the thymus-derived natural occurring Tregs, our data may indicate expansion or conversion of peripheral adaptive Tregs. In accordance with Treg suppressive activity, ovariectomized and ovalbumine-sensitized and challenged animals had significantly reduced lung inflammation. This was observed after cytokine analysis of lung explants showing significant reduction of pro-inflammatory cytokines, such as IL-4, IL-5, IL-13 and IL-17, associated to increased amount of IL-10. In summary, our data clearly demonstrates that OVA sensitization 7 days after ovariectomy culminates in reduced lung inflammation, which may be directly correlated with the expansion of Tregs in the periphery and further higher IL-10 secretion in the lungs.

Mechanism of oral tolerance induction to therapeutic proteins

Oral tolerance is defined as the specific suppression of humoral and/or cellular immune responses to an antigen by administration of the same antigen through the oral route. Due to its absence of toxicity, easy administration, and antigen specificity, oral tolerance is a very attractive approach to prevent unwanted immune responses that cause a variety of diseases or that complicate treatment of a disease. Many researchers have induced oral tolerance to efficiently treat autoimmune and inflammatory diseases in different animal models. However, clinical trials yielded limited success. Thus, understanding the mechanisms of oral tolerance induction to therapeutic proteins is critical for paving the way for clinical development of oral tolerance protocols. This review will summarize progress on understanding the major underlying tolerance mechanisms and contributors, including antigen presenting cells, regulatory T cells, cytokines, and signaling pathways. Potential applications, examples for therapeutic proteins and disease targets, and recent developments in delivery methods are discussed.

Th1/Th2 cytokine profile in childhood-onset systemic lupus erythematosus

OBJECTIVE

To determine the serum levels of Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines in childhood-onset SLE, first-degree relatives and healthy controls. To elucidate their association with disease activity, laboratory and treatment features.

METHODS

We included 60 consecutive childhood-onset SLE patients [median age 18 years (range 10-37)], 64 first-degree relatives [median 40 (range 28-52)] and 57 healthy [median age 19 years (range 6-30 years)] controls. Controls were age and sex-matched to SLE patients. SLE patients were assessed for clinical and laboratory SLE manifestations, disease activity (SLEDAI), damage (SDI) and current drug exposures. Mood and anxiety disorders were determined through Becks Depression (BDI) and Anxiety Inventory (BAI). Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines levels were measured by ELISA and compared by non-parametric tests.

RESULTS

Serum TNF-α (p=0.004), IL-6 (p=0.007) and IL-10 (p=0.03) levels were increased in childhood-onset SLE patients when compared to first-degree relatives and healthy controls. TNF-α levels were significantly increased in patients with active disease (p=0.014) and correlated directly with SLEDAI scores (r=0.39; p=0.002). IL-12 (p=0.042) and TNF-α (p=0.009) levels were significantly increased in patients with nephritis and TNF-α in patients with depression (p=0.001). No association between cytokine levels and SDI scores or medication was observed.

CONCLUSION

Th1 cytokines may play a role in the pathogenesis of neuropsychiatric and renal manifestations in childhood-onset SLE. The correlation with SLEDAI suggests that TNF-α may be a useful biomarker for disease activity in childhood-onset SLE, however longitudinal studies are necessary to determine if increase of this cytokine may predict flares in childhood-onset SLE.

An oral CD3-specific antibody suppresses T-cell-induced colitis and alters cytokine responses to T-cell activation in mice

BACKGROUND & AIMS

New therapeutic approaches are needed for inflammatory bowel diseases. A monoclonal antibody against CD3 (anti-CD3) suppresses T-cell-mediated autoimmune diseases such as experimental allergic encephalomyelitis. We explored the effects of anti-CD3 in mice with colitis.

METHODS

Severe combined immunodeficient mice were given injections of CD4(+)CD45RB(high) T cells to induce colitis. Four weeks later, the mice were given 2 or 5 μg/day of anti-CD3 or hamster immunoglobulin (Ig)G (control), via gavage, for 5 or 10 days. The effect of oral anti-CD3 on cytokine responses was studied by activating T cells using intraperitoneal injections of anti-CD3 monoclonal antibody 2 days after oral administration of the antibody. We collected intestine samples for histology analysis and cells were analyzed by flow cytometry. Cytokines in sera were analyzed by cytometric bead array.

RESULTS

Oral administration of anti-CD3 protected the mice from wasting disease and intestinal inflammation. Analyses of spleen and mesenteric lymph node cells showed no differences in total cell counts, or percentages of CD4(+) and forkhead box P3(+) regulatory T cells, between mice given anti-CD3 or the control immunoglobulin. Colitis therefore was not suppressed by induction of forkhead box P3(+) regulatory T cells, or depletion or limited expansion of T cells. Oral administration of anti-CD3 ameliorated the enteropathy induced by intraperitoneal injection of the antibody. In mice with enteropathy, oral anti-CD3 reduced levels of inflammatory cytokines such as interferon-γ, tumor necrosis factor-α, and interleukin (IL)-6; it also increased levels of the anti-inflammatory cytokines IL-10 and transforming growth factor-β. The effects of oral anti-CD3 required IL-10.

CONCLUSIONS

Oral administration of anti-CD3 to mice induces changes in the mucosal immune response that prevent colitis, independent of specific antigen, and reduce T-cell activation in an IL-10-dependent manner. Oral anti-CD3 therefore might be developed for the treatment of patients with inflammatory bowel disease.

Heligmosomoides polygyrus abrogates antigen-specific gut injury in a murine model of inflammatory bowel disease

BACKGROUND

Developing countries have a low incidence of inflammatory bowel disease (IBD), perhaps prevented by the high prevalence of helminth infections and other alterations in intestinal flora and fauna. Helminth infections prevent colitis in various murine models of IBD. IBD may be driven by an aberrant immune response to luminal antigen(s).

METHODS

We developed a murine model of IBD in which gut injury was induced by a specific antigen to better simulate the IBD disease process and to determine if helminth infections could abolish gut injury induced by an orally administered antigen. The model features pan-enterocolitis triggered by feeding ovalbumin (OVA).

RESULTS

The intestinal inflammation is antigen-specific and generates interleukin (IL)-17 and interferon-gamma (IFN-γ), but not IL-4. Full expression of the disease required T cells with defective capacity to make IL-10 and treatment with a noninjurious, low dose of a nonsteroidal antiinflammatory drug. Exposure to Heligmosomoides polygyrus abrogated this antigen-induced gut injury. H. polygyrus colonization induced Foxp3(+) T regulatory cells (Tregs) and mucosal production of IL-10 from non-T cells. Lamina propria mononuclear cells from H. polygyrus-infected mice released less IL-17 and IFN-γ constitutively and when stimulated with OVA or anti-CD3/CD28 monoclonal antibodies.

CONCLUSIONS

We developed a murine IBD model featuring antigen-specific enterocolitis and demonstrate for the first time that gut inflammation induced by an antigen could be abrogated by H. polygyrus infection. Protection was associated with suppressed IL-17 and IFN-γ production, induction of Foxp3(+) Tregs, and elevated secretion of non-T-cell-derived IL-10, all of which could be part of the protective processes.

Significance of immunoglobulin G4 (IgG4)-positive cells in extrahepatic cholangiocarcinoma: molecular mechanism of IgG4 reaction in cancer tissue

IgG4 reactions consisting of marked infiltration by immunoglobulin G4 (IgG4)-positive plasma cells in affected organs is found in cancer patients as well as patients with IgG4-related diseases. Notably, extrahepatic cholangiocarcinomas accompanying marked IgG4 reactions clinicopathologically mimic IgG4-related sclerosing cholangitis. The regulatory cytokine interleukin (IL)-10 is thought to induce the differentiation of IgG4-positive cells. In this study, to clarify the mechanism of the IgG4 reaction in extrahepatic cholangiocarcinoma, we investigated nonprofessional antigen-presenting cells (APCs) generating IL-10-producing regulatory T cells (anergy T cells) and Foxp3-positive regulatory cells producing IL-10. Immunohistochemistry targeting IgG4, HLA-DR, CD80, CD86, and Foxp3 was performed using 54 cholangiocarcinoma specimens from 24 patients with gallbladder cancer, 22 patients with common bile duct cancer, and eight patients with cancer of the Papilla of Vater. Moreover, a molecular analysis of Foxp3 and IL-10 was performed using a cultured human cholangiocarcinoma cell line. Consequently, 43% of the cholangiocarcinomas were found to be abundant in IgG4. Those expressing HLA-DR but lacking costimulatory molecules (CD80 and CD86) and those expressing Foxp3 detected by an antibody recognizing the N terminus accounted for 54% and 39% of cases, respectively. Moreover, the number of IgG4-positive cells was larger in these cases than in other groups. In cultured cells, the presence of a splicing variant of Foxp3 messenger RNA and the expression of IL-10 were demonstrated.

CONCLUSION

Extrahepatic cholangiocarcinoma is often accompanied by significant infiltration of IgG4-positive cells. Cholangiocarcinoma cells could play the role of nonprofessional APCs and Foxp3-positive regulatory cells, inducing IgG4 reactions via the production of IL-10 indirectly and directly, respectively.

Interaction between interleukin-10 (IL-10) polymorphisms and dietary fibre in relation to risk of colorectal cancer in a Danish case-cohort study

Background

More than 50% of the colorectal cancer (CRC) etiology has been attributed to diet. Established or suspected dietary factors modifying risk of CRC are red meat, cereals, fish, and fibre. Diet and lifestyle may be linked to cancer through inflammation. Interleukin-10 (IL-10) is an anti-inflammatory cytokine. We wanted to test if dietary factors and IL10 polymorphisms interact in relation to colorectal carcinogenesis.

Methods

The functional IL10 polymorphism C-592A (rs1800872) and the marker rs3024505 were assessed in relation to diet and lifestyle in a nested case-cohort study of 378 CRC cases and 775 randomly selected participants from a prospective study of 57,053 persons. Genotyping data on the IL10 polymorphism C-592A, smoking and non-steroidal anti-inflammatory drugs (NSAID) was retrieved from Vogel et al. (Mutat Res, 2007; 624:88). Incidence rate ratios (IRR) and 95% Confidence Interval (95% CI) were calculated.

Results

No associations were found between the IL10 rs3024505 polymorphism and risk of CRC. There was interaction between rs3024505 and dietary fibre (P-value for interaction = 0.01). IL10 rs3024505 homozygous wildtype carriers were at 27% reduced risk of CRC per 10 g fibre per day (95% CI: 0.60-0.88) whereas variant carriers had no risk reduction by fibre intake. Also, interaction between IL10 C-592A and intake of fibre was found (P-value for interaction = 0.02). Among those eating <17.0 grams of fibre per day, carriers of an C-592A variant allele had a statistically significantly higher risk of colorectal cancer compared to homozygous wildtypes. No significant differences in colorectal cancer risk were observed between the reference group (CC and <17.0 g/day) and carriers of one C-592A variant allele eating 17.0 or more grams of dietary fibre per day. This suggests that the increased risk due to carrying the variant allele can be overcome by higher fibre intake. No interactions between IL10 polymorphisms and dietary meat, cereal, or fish intake, or between IL10 rs3024505 and smoking or NSAID use were found.

Conclusions

In this northern Caucasian cohort we found interaction between IL10 and dietary fibre in CRC carcinogenesis. High intake of fibre seems to protect against CRC among individuals with IL10 related genetic susceptibility to CRC. This finding should be evaluated in other prospective and population-based cohorts with different ethnic groups.

Induction of protective genes leads to islet survival and function

Islet transplantation is the most valid approach to the treatment of type 1 diabetes. However, the function of transplanted islets is often compromised since a large number of β cells undergo apoptosis induced by stress and the immune rejection response elicited by the recipient after transplantation. Conventional treatment for islet transplantation is to administer immunosuppressive drugs to the recipient to suppress the immune rejection response mounted against transplanted islets. Induction of protective genes in the recipient (e.g., heme oxygenase-1 (HO-1), A20/tumor necrosis factor alpha inducible protein3 (tnfaip3), biliverdin reductase (BVR), Bcl2, and others) or administration of one or more of the products of HO-1 to the donor, the islets themselves, and/or the recipient offers an alternative or synergistic approach to improve islet graft survival and function. In this perspective, we summarize studies describing the protective effects of these genes on islet survival and function in rodent allogeneic and xenogeneic transplantation models and the prevention of onset of diabetes, with emphasis on HO-1, A20, and BVR. Such approaches are also appealing to islet autotransplantation in patients with chronic pancreatitis after total pancreatectomy, a procedure that currently only leads to 1/3 of transplanted patients being diabetes-free.

Administering human adipose-derived mesenchymal stem cells to prevent and treat experimental arthritis

Rheumatoid arthritis is a chronic autoimmune disease and affecting approximately 1% of the population. Human adipose-derived mesenchymal stem cells (hASCs) were recently found to suppress effector T cell and inflammatory responses and, thus, to have beneficial effects in various autoimmune diseases. In this study, we examined whether hASCs could play a protective and/or therapeutic role in collagen-induced arthritis (CIA). We showed that hASCs both prevented and treated CIA by significantly reducing the incidence and severity of experimental arthritis. We further demonstrated that treatment with hASCs inhibited the production of various inflammatory mediators, decreased antigen-specific Th1/Th17 cell expansion, and induced the production of anti-inflammatory cytokine interleukin-10. Moreover, hASCs could induce the generation of antigen-specific Treg cells with the capacity to suppress collagen-specific T cell responses.

Bovine lactoferrin improves bone status of ovariectomized mice via immune function modulation

We have previously shown that bovine lactoferrin (bLF) supplementation can have a beneficial effect on postmenopausal bone loss by modulating bone formation and resorption. A direct effect of bLF on bone metabolism is support by its presence in mice blood. Moreover we know that LF plays a key role in innate immunity and recent studies have shown its ability to modulate adaptive immunity. In particular bLF ingestion prevents recruitment and activation of immune cells at inflammatory sites. We propose that LF through its ability to modulate maturation and differentiation of leucocytes can participate to abolish the deregulation induced by estrogen deficiency on T cells. This study evaluated the effects of bovine lactoferrin on immune function in ovariectomized mice. We investigated whether bLF ingestion could prevent bone loss via modulation of immune function. Three-month-old female C3H mice were either ovariectomized or sham-operated and fed for 1, 2 or 4 months with a control diet (AIN-93M) or the same diet including 10g bLF/kg diet. Bone mineral density was determined using a Lunar Piximus densitometer. The immune parameters were assessed by flow cytometry. In addition, Real-Time PCR was performed to quantify TNFα expression and plasma cytokines were measured at 4 months with Luminex. Ovariectomy induced significant changes on bone parameters and increased recruitment of macrophages, dendritic cells, and B and T cells associated with T lymphocyte activation in bone marrow. Compared to the control diet, ingestion of bLF-enriched diet for 2 months prevented T cell activation and restored dendritic and B cell populations in the bone micro-environment in ovariectomized mice. Furthermore, TNFα expression in bone was decreased by bLF supplementation after 2 and 4 months. Similarly, a decreased plasma level of TNFα was observed concomitantly to an increase of IL-10 level. In conclusion, these experiments suggest that bLF can mediate the prevention of lymphocyte activation and cytokine release in the bone micro-environment. Dietary bLF supplementation could have a beneficial effect on postmenopausal bone loss by modulating immune function.

Adaptive T-cell responses regulating oral tolerance to protein antigen

The term oral (or mucosal) tolerance has been classically defined as the suppression of T- and B-cell responses to an antigen by prior administration of the antigen by the oral route. In recent years, it has become clear that both innate and acquired regulatory immune responses are essential for the development of oral tolerance. As such, mucosal microenvironmental factors such as transforming growth factor- β, prostaglandins but also dietary vitamin A create conditioning of an adaptive regulatory T-cell response that suppresses subsequent antigen-specific responses. Particular resident subsets of antigen presenting dendritic cells are pivotal to convey conditioning signals next to the presentation of antigen. This review discusses the primary mechanisms of adaptive regulatory T-cell induction to ingested soluble protein antigen. However, we also discuss the limitations of our knowledge with respect to understanding the very common food hypersensitivity Celiac disease caused by an aberrant adaptive immune response to the food protein gluten.

The therapeutic efficacy of human adipose tissue-derived mesenchymal stem cells on experimental autoimmune hearing loss in mice

Autoimmune inner ear disease is characterized by progressive, bilateral although asymmetric, sensorineural hearing loss. Patients with autoimmune inner ear disease had higher frequencies of interferon-γ-producing T cells than did control subjects tested. Human adipose-derived mesenchymal stem cells (hASCs) were recently found to suppress effector T cells and inflammatory responses and therefore have beneficial effects in various autoimmune diseases. The aim of this study was to examine the immunosuppressive activity of hASCs on autoreactive T cells from the experimental autoimmune hearing loss (EAHL) murine model. Female BALB/c mice underwent β-tubulin immunization to develop EAHL; mice with EAHL were given hASCs or PBS intraperitoneally once a week for 6 consecutive weeks. Auditory brainstem responses were examined over time. The T helper type 1 (Th1)/Th17-mediated autoreactive responses were examined by determining the proliferative response and cytokine profile of splenocytes stimulated with β-tubulin. The frequency of regulatory T (Treg) cells and their suppressive capacity on autoreactive T cells were also determined. Systemic infusion of hASCs significantly improved hearing function and protected hair cells in established EAHL. The hASCs decreased the proliferation of antigen-specific Th1/Th17 cells and induced the production of anti-inflammatory cytokine interleukin-10 in splenocytes. They also induced the generation of antigen-specific CD4(+) CD25(+) Foxp3(+) Treg cells with the capacity to suppress autoantigen-specific T-cell responses. The experiment demonstrated that hASCs are one of the important regulators of immune tolerance with the capacity to suppress effector T cells and to induce the generation of antigen-specific Treg cells.

Nasal cardiac myosin peptide treatment and OX40 blockade protect mice from acute and chronic virally-induced myocarditis

Myocarditis poses a severe health problem, can lead to dilated cardiomyopathy (DCM) and death, and is thought to be triggered by infections. Enteroviruses such as Coxsackie virus B3 (CVB3) have been implicated as a culprit, since they can cause acute and chronic heart disease in susceptible mice. CVB was detected in human cardiac myocytes in some cases, whereas acute CVB infection was thought to have caused death. Here we studied, whether nasal administration of cardiac myosin (CM) major histocompatibility class (MHC) II peptides CM₉₄₇-₉₆₀ and CM₇₃₅-₇₄₇ and OX40 blockade would be able to ameliorate immunopathology and heart disease in BALB/C mice infected with CVB3. We found that nasal CM-peptide prophylactic treatment significantly reduced myocarditis and mortality by enhancing Treg and IL-10 induction and that blockade of OX40 signaling could reduce heart inflammation when administered late during pathogenesis. Altogether, these results chart the way for novel prevention and intervention strategies for viral myocarditis.

Porcine reproductive and respiratory syndrome virus-induced immunosuppression exacerbates the inflammatory response to porcine respiratory coronavirus in pigs

We performed a comprehensive analysis of innate and adaptive immune responses in dual-virus infected pigs to understand whether a pre-existing immunomodulatory respiratory viral infection affects the overall immunity to a subsequent porcine respiratory coronavirus (PRCV) infection in pigs. Pigs were either mock-infected or infected with porcine reproductive and respiratory syndrome virus (PRRSV), a virus known to cause immunosuppressive respiratory disease, and then pigs were co-infected with PRCV, which normally causes subclinical respiratory infection. We collected samples for six independent experiments from 178 pigs that were also used for pathological studies. We detected a significant reduction in innate NK-cell-mediated cytotoxic function in PRRSV-infected pigs, which was synergistically further decreased in pigs co-infected with PRCV. Subsequently, in association with clinical signs we observed elevated levels of proinflammatory (IL-6), Th-1 (IL-12), and regulatory (IL-10 and TGF-β) cytokines. Increased frequencies of CD4CD8 double-positive T lymphocytes and myeloid cells, in addition to the elevated Th-1 and proinflammatory cytokines in dual-infected pigs, contributed to the severity of lung disease in pigs. The results of our study clarify how each virus modulates the host innate and adaptive immune responses, leading to inflammatory reactions and lung pathology. Thus measurements of cytokines and frequencies of immune cells may serve as indicators of the progression of respiratory viral co-infections, and provide more definitive approaches for treatment.

Oral tolerance inhibits pulmonary eosinophilia in a cockroach allergen induced model of asthma: a randomized laboratory study

Background

Antigen desensitization through oral tolerance is becoming an increasingly attractive treatment option for allergic diseases. However, the mechanism(s) by which tolerization is achieved remain poorly defined. In this study we endeavored to induce oral tolerance to cockroach allergen (CRA: a complex mixture of insect components) in order to ameliorate asthma-like, allergic pulmonary inflammation.

Methods

We compared the pulmonary inflammation of mice which had received four CRA feedings prior to intratracheal allergen sensitization and challenge to mice fed PBS on the same time course. Respiratory parameters were assessed by whole body unrestrained plethysmography and mechanical ventilation with forced oscillation. Bronchoalveolar lavage fluid (BAL) and lung homogenate (LH) were assessed for cytokines and chemokines by ELISA. BAL inflammatory cells were also collected and examined by light microscopy.

Results

CRA feeding prior to allergen sensitization and challenge led to a significant improvement in respiratory health. Airways hyperreactivity measured indirectly via enhanced pause (Penh) was meaningfully reduced in the CRA-fed mice compared to the PBS fed mice (2.3 ± 0.4 vs 3.9 ± 0.6; p = 0.03). Directly measured airways resistance confirmed this trend when comparing the CRA-fed to the PBS-fed animals (2.97 ± 0.98 vs 4.95 ± 1.41). This effect was not due to reduced traditional inflammatory cell chemotactic factors, Th2 or other cytokines and chemokines. The mechanism of improved respiratory health in the tolerized mice was due to significantly reduced eosinophil numbers in the bronchoalveolar lavage fluid (43300 ± 11445 vs 158786 ± 38908; p = 0.007) and eosinophil specific peroxidase activity in the lung homogenate (0.59 ± 0.13 vs 1.19 ± 0.19; p = 0.017). The decreased eosinophilia was likely the result of increased IL-10 in the lung homogenate of the tolerized mice (6320 ± 354 ng/mL vs 5190 ± 404 ng/mL, p = 0.02).

Conclusion

Our results show that oral tolerization to CRA can improve the respiratory health of experimental mice in a CRA-induced model of asthma-like pulmonary inflammation by reducing pulmonary eosinophilia.

The role of the gut mucosal immunity in the development of tolerance against allergy to food

PURPOSE OF REVIEW

To provide an overview on the role of gut mucosal immunity in the development of tolerance against allergy to food.

RECENT FINDINGS

The gastrointestinal tract, through innate and specific immunologic factors, acts as a defense against ingested antigens. In addition to the mucous membrane integrity and digestion, numerous specific immunologic cells and mediators orchestrate such defensive mechanisms. In case of food antigens, the outcome is usually in favor of tolerance. Defects in that barrier, however, can lead to the development of aberrant immunologic responses, including hypersensitivity reactions.

SUMMARY

The prevailing evidence is that healthy mucosal immunity plus appropriate feeding regimen during early infancy are in favor of food tolerance. However, in addition to genetic predisposition, development of allergy is facilitated by defects in the gut barrier (immune or nonimmune) and the food allergen load.

Inhibition of bleomycin-induced pulmonary fibrosis through pre-treatment with collagen type V

BACKGROUND

Tolerance to collagen structures has been shown to inhibit the progression of autoimmune scleroderma and rheumatoid arthritis. More recently, tolerance induction to collagen type V (colV) in experimental models of lung transplantation was shown to ameliorate the complex pathology known as "chronic rejection." The link between colV autoimmunity and progressive graft dysfunction and subsequent development of bronchiolitis obliterans syndrome (BOS) has been established in human lung transplant recipients. We hypothesized that intravenous injection of colV inhibits development of lung fibrosis in a bleomycin-induced lung injury mouse model.

METHODS

Experimental animals were injected intravenously with saline or colV 10 days before intratracheal instillation of bleomycin. Pulmonary inflammation was monitored and quantified for the presence of cells in the bronchoalveolar lavage (BAL) fluid by flow cytometry and histology of lung tissue.

RESULTS

ColV-pre-treated animals showed a significant reduction in lung inflammation compared with non-treated animals, according to histology and morphometry. The number of inflammatory cells in the BAL fluid was significantly reduced and associated with a lower proportion of gammadelta T cells and CD4(+) T cells in the colV-pre-treated group. Matrix metalloproteinase-2 and -9 (MMP-2 and -9; also known as gelatinase A and gelatinase B, respectively) levels in the BAL fluid were significantly reduced in colV-pre-treated mice compared with the non-treated mice. In addition, intravenous injection of colV was associated with a significant reduction in the relative expression of interleukin (IL)-6, IL-17 and IL-22 in cells present in BAL fluid at 7 and 14 days after bleomycin instillation.

CONCLUSIONS

Pre-treatment by intravenous injection of colV inhibits bleomycin-induced pulmonary fibrosis by inhibiting IL-6 and IL-17 production. Fibrosis treatment in this context therefore should target induction of colV tolerance and Th17 development.

In vivo induction of type 1-like regulatory T cells using genetically modified B cells confers long-term IL-10-dependent antigen-specific unresponsiveness

Regulatory T cells (Tregs) hold much promise for the therapy of allergy and autoimmunity, but their use is hampered by lack of Ag specificity (natural Tregs) and difficulty to expand in vitro or in vivo (adaptive Tregs). We designed a method for in vivo induction of Ag-specific Tregs, in BALB/c H-2d, that share characteristics with type 1 Tregs (Tr1). A retroviral vector was constructed encoding a major T cell epitope of a common allergen, Der p 2, fused to an endosomal targeting sequence (gp75) for efficient MHC class II presentation. B cells transduced with such construct were adoptively transferred to BALB/c mice before or after peptide immunization. Long-lasting Ag-specific immune tolerance was achieved in both cases. Genetically modified B cells constitutively expressed the transgene for at least 3 mo. B cells from IL-10(-/-) mice were unable to induce tolerance. Upon transfer, B cells induced Foxp3(-)CD4(+) T cells showing phenotypic and functional characteristics comparable to Tr1-cells, including production of IL-10 but not of TGF-beta, and high expression of CTLA-4. Adoptive transfer of such T cells conferred unresponsiveness to allergen immunization and prevented the development of Der p 2-induced asthma. Functional Tr1-like cells can therefore be induced in vivo using retrovirally transduced B cells.

Aminoguanidine administered during the induction of oral tolerance alters the systemic response of the tolerised rats

Herewith we investigated the role of nitric oxide synthase (NOS)-II in the establishment of oral tolerance induced by low antigen dose. To accomplish this, we used a rat model of oral tolerance induced by intragastric administration of low doses of ovalbumin (OVA). NOS-II was inhibited in vivo during the onset of tolerance by intraperitoneal (i.p.) treatment with aminoguanidine (AMG), a selective NOS-II inhibitor. Four experimental groups were generated: (TOL), tolerised rats, receiving OVA but no AMG; (TAG), rats tolerised with OVA and simultaneously receiving AMG i.p.; (CAG), controls treated with AMG but no oral antigen; and (CONT), controls receiving neither OVA nor AMG treatment. The state of oral tolerance was evaluated in all groups by analysing several immune parameters upon subcutaneous administration of OVA in Freund's complete adjuvant. First, we were able to determine that NOS-II inhibition altered the TH1/TH2 balance in tolerised rats, driving the TH2 anti-OVA response in TOL rats towards TH1 in TAG animals, which showed enhanced delayed hypersensitivity responses. Second, splenocyte cultures from TAG rats showed lower levels of IL-10 production compared to TOL samples as determined by ELISA analysis. Last, we detected the presence of a functional distinct Tr1 regulatory T cell population in spleen samples recovered from TAG animals. Contrary to what happened with TOL Tr1 cells, the levels of Tr1 cells in TAG samples were modified by in vitro stimulation with OVA. All together, these data indicate a preponderant role for NOS-II in the process of oral tolerance induced by low antigen dose.

Extracorporeal photopheresis-induced immune tolerance: a focus on modulation of antigen-presenting cells and induction of regulatory T cells by apoptotic cells

PURPOSE OF REVIEW

This review is intended to introduce recent advances in the research surrounding extracorporeal photopheresis (ECP) with a focus on how apoptotic cells modulate antigen-presenting cells and induce regulatory T cells, given that ECP therapy induces apoptosis of leukocytes collected through leukapheresis.

RECENT FINDINGS

It has been suggested that ECP therapy, unlike other immunosuppressive regimens, does not cause global immunosuppression, but induces immune tolerance. Recent clinical and animal studies demonstrate that ECP therapy induces antigen-specific regulatory T cells, including CD4+CD25+FoxP3+ T cells and IL-10-producing Tr1 cells, that may arise secondarily to the induction of tolerogenic antigen-presenting cells (APCs) by infusion of apoptotic cells. It has also been suggested that ECP therapy may induce IL-10-producing regulatory B cells and regulatory CD8+ T cells. Finally, several recent studies, which examined the cellular elements involved in the uptake of apoptotic cells, demonstrated that apoptotic cells modulate APCs through binding to specific receptors, particularly TAM receptors that provide inhibitory signals that block APC activation.

SUMMARY

ECP therapy induces immune tolerance through modulation of antigen-presenting cells as well as induction of regulatory T cells. ECP therapy has great potential in the management of allogeneic transplantation and autoimmune diseases.

Heat shock protein 60 reactive T cells in juvenile idiopathic arthritis: what is new?

Juvenile idiopathic arthritis (JIA) is a disease characterized by chronic joint inflammation, caused by a deregulated immune response. In patients with JIA, heat shock proteins (HSPs) are highly expressed in the synovial lining tissues of inflamed joints. HSPs are endogenous proteins that are expressed upon cellular stress and are able to modulate immune responses. In this review, we concentrate on the role of HSPs, especially HSP60, in modulating immune responses in both experimental and human arthritis, with a focus on JIA. We will mainly discuss the tolerogenic immune responses induced by HSPs, which could have a beneficial effect in JIA. Overall, we will discuss the immune modulatory capacity of HSPs, and the underlying mechanisms of HSP60-mediated immune regulation in JIA, and how this can be translated into therapy.

Naturally occurring and inducible T-regulatory cells modulating immune response in allergic asthma

RATIONALE

T-regulatory cells (Tregs) are potent immunomodulators in allergic asthma.

OBJECTIVES

We evaluated the functional effects of Tregs by adoptively transferring naturally occurring CD4(+)CD25(+) Tregs (NTregs) and CD4(+)CD25(-) inducible Tregs (iTregs) from lung and spleens of green fluorescent protein (GFP)-transgenic Balb/c mice into cockroach-sensitized and -challenged mice.

METHODS

GFP-labeled NTregs and iTregs were adoptively transferred into cockroach-sensitized and -challenged mice. Airway hyperresponsiveness (AHR) to methacholine was examined using a single-chamber, whole-body plethysmograph and invasive tracheostomy.

MEASUREMENTS AND MAIN RESULTS

Adoptive transfer of either NTregs or iTregs from lung or spleen reversed airway inflammation and AHR to methacholine, and the effect lasted for at least 4 weeks. GFP-labeled iTregs up-regulated CD25 and forkhead-winged transcriptional factor box protein 3 and migrated to lymph node and lung. Lung CD4(+)CD25(+) T cells isolated from each group of recipient mice were inducible costimulatory molecule-high and programmed death (PD)-1-positive; however, higher expression of PD-1 was found in the spleen iTregs (S25(-)) and lung iTregs (L25(-)) groups. Higher levels of transforming growth factor-beta and IL-10 mRNA transcripts and bronchoalveolar lavage fluid IL-10 and INF-gamma levels were observed in lung CD4(+)CD25(+) cells from the L25(-) and S25(-) cell-recipient mice than from lung NTregs (L25(+)) and spleen NTregs (S25(+)) cell-recipient mice. Adoptive transfer of either cell type significantly reduced bronchoalveolar lavage fluid IL-4, IL-5, and IL-13 levels.

CONCLUSIONS

Tregs reverse AHR and airway inflammation; however iTregs that differentiated into IL-10-producing CD4(+) type 1 cells in the lung exert their suppressive activity likely by higher levels of transforming growth factor-beta, IL-10, IFN-gamma, and elevated levels of PD-1 compared with NTregs. Hence, PD-1 may be a conduit for reversing AHR by Tregs and a plausible target for treating asthma.