Specific immunotherapy suppresses Th2 responses via modulating TIM1/TIM4 interaction on dendritic cells

The Potential Role of Moringa oleifera Lam. Leaf Proteins in Moringa Allergy by Functionally Activating Murine Bone Marrow-Derived Dendritic Cells and Inducing Their Differentiation toward a Th2-Polarizing Phenotype

Moringa oleifera leaves are an inexpensive substitute for staple foods. Despite limited data, Moringa oleifera leaf protein (Mo-Pr) may be allergenic in BALB/c mice. In mouse models and allergic patients, dendritic cells (DCs) may be involved in food allergy. In addition, some allergens, including food allergens, can directly activate DCs and induce Th2 polarization. We investigated whether Mo-Pr can modulate the functional profile of murine bone marrow-derived dendritic cells (BMDCs) in vitro. BMDCs were obtained from mouse bone marrow cultured with granulocyte-macrophage colony-stimulating factor (GM-CSF) for 7 days and then treated with lipopolysaccharide (LPS) or Mo-Pr. BMDC phenotypes were evaluated via flow cytometry, cytokine production was assessed using ELISA, the expression of key genes was studied using qRT-PCR, the effects on T-cell differentiation were investigated using mixed lymphocyte reaction (MLR), and transcriptional changes in BMDCs were investigated using RNA-Seq. Mo-Pr-specific IgE was investigated in recipient serum after BMDC transfer. Mo-Pr treatment significantly induced BMDC maturation, increased the expression of CD80/86 and MHC II, resulted in the production of IL-12 and TNF-α, and induced T-cell differentiation. Mo-Pr treatment stimulated BMDCs' expression of the Th2 promoters OX40L and TIM-4, induced the production of the Th2-type chemokines CCL22 and CCL17, and decreased the Th1/Th2 ratio in vitro. Healthy recipients of Mo-Pr-treated BMDCs produced Mo-Pr-specific IgE.

Cigarette Smoke Extract Promotes TIM4 Expression in Murine Dendritic Cells Leading to Th2 Polarization through ERK-Dependent Pathways

Smoking is considered to be the main source of indoor pollution, and it has been identified as an important environmental factor contributing to asthma onset. We know that T helper 2 (Th2) response plays a crucial role in the process of asthma disease. We have investigated the reaction of cigarette smoke extract (CSE) on Th polarization which is controlled by dendritic cells (DCs). Stimulated by CSE, immature DCs from murine bone marrow showed upregulated levels of TIM4. Cocultured with CD4+ T cells, stimulated DCs increased the ratio of IL-4+ versus IFN-γ+ of CD4+ T cells. This suggests a differentiation towards Th2 response. Moreover, antibodies against TIM4 reversed the upexpression of the IL-4+/IFN-γ+ ratio provoked by CSE, indicating that the Th2 polarization which was induced by CSE is via TIM4 mechanisms. CSE could activate mitogen-activated protein kinase pathways like ERK and p38. Upregulation of TIM4 expression by CSE stimulation was found to be inhibited by an ERK inhibitor but not p38 and JNK. In conclusion, DC-induced Th2 polarization is a hallmark of CSE allergy, and this aspect can be explained by CSE-induced TIM4 expression.

TIM‑4 blockade of KCs combined with exogenous TGF‑β injection helps to reverse acute rejection and prolong the survival rate of mice receiving liver allografts

An acute reaction response (AR) following liver transplantation (LT) is caused by immune responses that are primarily mediated by T lymphocytes. Kupffer cells (KCs) are the largest antigen presenting cell (APC) group in vivo and are the primary modulators of the inflammatory or tolerogenic immune response in liver tissues. T cell immunoglobulin-domain and mucin-domain-4 (TIM-4), the only TIM protein not expressed on T cells, is expressed on APCs; suggesting that it mediates the various immune responses. However, to the best of our knowledge, the role of TIM-4 expressed by KCs in LT injury remains unknown. The present study aimed to explore whether and how TIM-4 expressed by KCs is involved in the AR of liver allografts. Orthotopic liver transplantation (OLT) was performed in mice to establish a model of AR and results demonstrated that LT may lead to the augmented expression of TIM-4 in activated KCs. It was also revealed that TIM-4 blockade markedly attenuated AR injury in vivo via the nuclear factor-κB (NF-κB) and p38 mitogen-activated protein kinase (p38 MAPK) signaling pathways. In addition, levels of transforming growth factor-β (TGF-β) were increased following TIM-4 blockade. Furthermore, in a KC/cluster of differentiation (CD)4⁺ T cell co-culture system, blocking TIM-4 inhibited T helper 2 (Th2) differentiation, stimulated the conversion of naive (CD)4⁺ T cells into CD4⁺CD25⁺Forkhead box protein p3⁺ T regulatory cells and suppressed interleukin-4/signal transducer and activator of transcription 6/transcription factor gata3 signaling. These effects were enhanced following the addition of TGF-β. It was also demonstrated that LT mouse models treated with TIM-4 blockade in combination with exogenous TGF-β injections, increased the survival times of mice and enhanced the amelioration of AR in LT. These results indicate that blocking the expression of TIM-4 by KCs via exogenous TGF-β injection may be an effective therapeutic strategy to inhibit the AR of liver allografts.

Vitamin D regulates immunoglobulin mucin domain molecule-4 expression in dendritic cells

BACKGROUND

Dendritic cell (DC)-derived immunoglobulin domain molecule (TIM)4 plays a critical role in the initiation of T helper (Th)2 polarization. Vitamin D (VitD) involves the regulation of a number of immune responses.

OBJECTIVES

This study tests a hypothesis that VitD regulates TIM4 expression in DCs.

METHODS

Peripheral blood samples were collected from patients with allergic rhinitis (AR) and healthy subjects. DCs were isolated from the samples and analyzed for the expression of TIM4.

RESULTS

We observed that the levels of calcitriol, the active form of VitD3, in the sera of AR patients were lower than that in healthy subjects. The peripheral DC expressed higher levels of TIM4 and lower levels of VDR. A negative correlation was identified between the data of serum calcitriol and TIM4 in DCs. Exposure DCs to calcitriol in the culture increased the expression of VDR. We also found that VDR bound to the TIM4 promoter locus in DCs to repress the TIM4 gene transcription and expression.

CONCLUSIONS AND CLINICAL RELEVANCE

VitD deficiency may contribute to the pathogenesis of AR by increasing the TIM4 expression. The results suggest that to regulate the serum calcitriol levels and the expression of VDR in DCs may be necessary to be taken into account in the treatment of AR.

Viruses and bacteria in Th2-biased allergic airway disease

Allergic airway diseases are typically characterized by a type 2-biased inflammation. Multiple distinct viruses and bacteria have been detected in the airways. Recently, it has been confirmed that the microbiome of allergic individuals differs from that of healthy subjects, showing a close relationship with the type 2 response in allergic airway disease. In this review, we summarize the recent findings on the prevalence of viruses and bacteria in type 2-biased airway diseases and on the mechanisms employed by viruses and bacteria in propagating type 2 responses. The understanding of the microbial composition and postinfectious immune programming is critical for the reconstruction of the normal microflora and immune status in allergic airway diseases.

TSLP receptor is not essential for house dust mite-induced allergic rhinitis in mice

TSLP induces Th2 cytokine production by Th2 cells and various other types of cells, thereby contributing to Th2-type immune responses and development of allergic disorders. We found that house dust mite (HDM) extract induced TSLP production by nasal epithelial cells, suggesting that TSLP may be involved in development of HDM-induced allergic rhinitis (AR). To investigate that possibility in greater detail, wild-type and TSLP receptor-deficient (TSLPR-/-) mice on the C57BL/6J background were repeatedly treated intranasally with HDM extract. The frequency of sneezing, numbers of eosinophils and goblet cells, thickness of submucosal layers, serum levels of total IgE and HDM-specific IgG1, and levels of IL-4, IL-5 and IL-13 in the culture supernatants of HDM-stimulated LN cells were comparable in the two mouse strains. Those findings indicate that, in mice, TSLPR is not crucial for development of HDM-induced AR.

Scientific foundations of allergen-specific immunotherapy for allergic disease

Allergen-specific immunotherapy (AIT) was described as a therapeutic option for the treatment of allergies > 100 years ago. It is based on administration of allergen extracts and leads to the development of clinical allergen tolerance in selected patients. According to current knowledge, AIT results in the restoration of immune tolerance toward the allergen of interest. It is mainly accompanied by the induction of regulatory and suppressive subsets of T and B cells, the production of IgG4 isotype allergen-specific blocking antibodies, and decreased inflammatory responses to allergens by effector cells in inflamed tissues. Currently, AIT is mainly applied subcutaneously or sublingually and is suitable for both children and adults for pollen, pet dander, house dust mite, and venom allergies. It not only affects rhinoconjunctival symptoms but also has documented short- and long-term benefits in asthma treatment. Clinically, a fast onset of tolerance is achieved during desensitization, with a tolerable amount of side effects. The disease modification effect leads to decreased disease severity, less drug usage, prevention of future allergen sensitizations, and a long-term curative effect. Increasing safety while maintaining or even augmenting efficiency is the main goal of research for novel vaccine development and improvement of treatment schemes in AIT. This article reviews the principles of allergen-specific immune tolerance development and the effects of AIT in the clinical context.

Non-allergenic factors from pollen modulate T helper cell instructing notch ligands on dendritic cells

BACKGROUND

Pollen allergens are delivered to epithelial surfaces of the upper respiratory tract in conjunction with multiple endogenous adjuvants. We previously demonstrated pollen-mediated modulation of cytokine and chemokine production of dendritic cells, contributing to a Th2-dominated micromilieu. As T helper cell differentiation not only depends on dendritic cell-derived cytokines but also on cell-cell-contact mediated mechanisms, we studied the expression of notch ligands and myeloid differentiation primary response protein 88 (MyD88) in dendritic cells matured in the presence of aqueous birch pollen extracts and pollen-associated E1-phytoprostanes.

METHODS

Human monocyte-derived dendritic cells were stimulated with aqueous birch pollen extracts in the absence or presence of lipopolysaccharide, and mRNA expression levels of notch ligands delta-1 and -4, jagged-1 and -2 and of myd88 were determined. Regulation of Delta-4 and MyD88 by aqueous pollen extracts was assessed on protein level. The contribution of notch signaling to T helper cell differentiation was analyzed in allogeneic T cell stimulation assays.

RESULTS

In immature dendritic cells, stimulation with pollen extracts resulted in an induction of both delta and jagged notch ligands. The lipopolysaccharide-induced up-regulation of delta-1 and -4 and of myd88 was decreased by aqueous pollen extracts, whereas jagged expression was induced. Reduction of Delta-4 and MyD88 by aqueous pollen extracts was confirmed on protein level. The Th2-skewing activity was contained in a fraction of aqueous pollen extracts enriched for molecules <3 kDa and was distinct from the previously identified E1-phytoprostanes. Reduction of notch signaling in dendritic cells matured in the presence aqueous pollen extract leads to inhibition of IL-10 and to induction of IL-5 production in naïve T cells differentiated by these dendritic cells.

CONCLUSIONS

Pollen derived, non-allergenic factors reduce the dendritic cell's expression of Th1 instructing Delta-like notch ligands and of MyD88, thereby promoting Th2 skewing of T helper cell responses.

The role of T cell immunoglobulin mucin domains 1 and 4 in a herpes simplex virus-induced Behçet's disease mouse model

The T cell immunoglobulin mucin (TIM) proteins regulate T cell activation and tolerance. TIM-1 plays an important role in the regulation of immune responses and the development of autoimmune diseases. TIM-4 is a natural ligand of TIM-1, and the interaction of TIM-1 and TIM-4 is involved in the regulation of T helper (Th) cell responses and modulation of the Th1/Th2 cytokine balance. Behçet's disease (BD) is a chronic, multisystemic inflammatory disorder with arthritic, intestinal, mucocutaneous, ocular, vascular, and central nervous system involvement. Tim-1 expression was lower in a herpes simplex virus-induced BD mouse model compared to that in asymptomatic BD normal (BDN) mice. Tim-4 expression was higher in BD mice than that in BDN mice. In this study, we investigated the Tim expression in a BD mouse model with BD-like symptoms. Tim-1 and Tim-4 expression was regulated by an expression vector or siRNA injected into the BD mouse model. The Tim-1 vector injected into BD mice resulted in changes in BD-like symptoms and decreased the severity score. Treatment with Tim-4 siRNA also improved BD-like symptoms and decreased the severity score accompanied by upregulation of regulatory T cells. We showed that regulating Tim-1 or Tim-4 affected BD-like symptoms in mice.

IL-33, but not IL-25, is crucial for the development of house dust mite antigen-induced allergic rhinitis

Both interleukin (IL)-33 and IL-25 induce Th2 cytokine production by various cell types, suggesting that they contribute to development of allergic disorders. However, the precise roles of IL-33 and IL-25 in house dust mite (HDM)-induced allergic rhinitis (AR) remain unclear. Both IL-33 and IL-25 were produced mainly by nasal epithelial cells during HDM-induced AR. Eosinophil and goblet cell counts in the nose and IL-5 levels in lymph node cell culture supernatants were significantly decreased in IL-33-deficient, but not IL-25-deficient, mice compared with wild-type mice during HDM-induced AR, but the serum IgE and IgG1 levels did not differ. On the other hand, HDM-induced AR developed similarly in wild-type mice transferred with either IL-33-deficient BM cells or wild-type BM cells. IL-33, but not IL-25, produced by nasal epithelial cells was crucial for the development of murine HDM-induced AR. These observations suggest that IL-33 neutralization may be a potential approach for treatment of HDM-induced AR in humans.

Suppression of TIM-1 predicates clinical efficacy of sublingual immunotherapy for allergic rhinitis in children

OBJECTIVE

To evaluate the clinical efficacy of sublingual immunotherapy (SLIT) with house-dust mite (HDM) extract and to examine the change of biomarkers (TIM-1, IL-5 and IL-10) after 6-month SLIT in children with allergic rhinitis (AR).

METHODS

One hundred and sixteen HDM-sensitized children with persistent AR were enrolled to assess the clinical efficacy of SLIT by determining the individual nasal symptom score (INSS) and total nasal symptom scores (TNSS) after 6-month SLIT. Moreover, the mRNA expression of TIM-1, IL-5 and IL-10 in peripheral blood mononuclear cells (PBMCs) was examined in 16 well-controlled and 12 uncontrolled AR patients using quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

After 6-month SLIT, both TNSS and INSS scores were significantly decreased compared with the baseline value (p < 0.01). The rates for well-controlled, partly controlled and uncontrolled children were 43.1%, 32.8% and 24.1%, respectively. Accordingly, the mRNA levels of TIM-1 and IL-5 decreased significantly and IL-10 mRNA level increased significantly compared with the baseline value in well-controlled children (p < 0.05).

CONCLUSION

Our findings suggest SLIT with HDM extract is effective and safe for AR children and TIM-1 may be considered as an indicator for evaluating the clinical efficacy of SLIT.

Pathogenesis of food allergy in the pediatric patient

In the US and other developed countries, food allergy is a growing epidemic in pediatric populations with a substantial impact on health-related quality of life. As such, there are great efforts underway to unravel the mechanisms of oral mucosal tolerance and to better define the factors related to host and allergen exposure that contribute to the aberrant immune response leading to sensitization and clinical food allergy. Although more research is needed to eventually develop targeted treatment and prevention strategies, this review highlights our current understanding of the pathogenesis of IgE-mediated food allergy.

Mechanisms of peripheral tolerance to allergens

The immune system is regulated to protect the host from exaggerated stimulatory signals establishing a state of tolerance in healthy individuals. The disequilibrium in immune regulatory vs effector mechanisms results in allergic or autoimmune disorders in genetically predisposed subjects under certain environmental conditions. As demonstrated in allergen-specific immunotherapy and in the healthy immune response to high-dose allergen exposure models in humans, T regulatory cells are essential in the suppression of Th2-mediated inflammation, maintenance of immune tolerance, induction of the two suppressive cytokines interleukin-10 and transforming growth factor-β, inhibition of allergen-specific IgE, and enhancement of IgG4 and IgA. Also, suppression of dendritic cells, mast cells, and eosinophils contributes to the construction of peripheral tolerance to allergens. This review focuses on mechanisms of peripheral tolerance to allergens with special emphasis on recent developments in the area of immune regulation.

Intestinal epithelial barrier dysfunction in food hypersensitivity

Intestinal epithelial barrier plays a critical role in the maintenance of gut homeostasis by limiting the penetration of luminal bacteria and dietary allergens, yet allowing antigen sampling for the generation of tolerance. Undigested proteins normally do not gain access to the lamina propria due to physical exclusion by tight junctions at the cell-cell contact sites and intracellular degradation by lysosomal enzymes in enterocytes. An intriguing question then arises: how do macromolecular food antigens cross the epithelial barrier? This review discusses the epithelial barrier dysfunction in sensitized intestine with special emphasis on the molecular mechanism of the enhanced transcytotic rates of allergens. The sensitization phase of allergy is characterized by antigen-induced cross-linking of IgE bound to high affinity FcεRI on mast cell surface, leading to anaphylactic responses. Recent studies have demonstrated that prior to mast cell activation, food allergens are transported in large quantity across the epithelium and are protected from lysosomal degradation by binding to cell surface IgE and low-affinity receptor CD23/FcεRII. Improved immunotherapies are currently under study including anti-IgE and anti-CD23 antibodies for the management of atopic disorders.

Mechanisms of subcutaneous allergen immunotherapy

Allergen-specific immunotherapy (SIT) is the only curative approach in the treatment of allergic diseases defined up-to-date. Peripheral T-cell tolerance to allergens, the goal of successful allergen-SIT, is the primary mechanism in healthy immune responses to allergens. By repeated administration of increased doses of the causative allergen, allergen-SIT induces a state of immune tolerance to allergens through the constitution of T regulatory (Treg) cells, including allergen-specific interleukin (IL)-10-secreting Treg type 1 cells and CD4(+)CD25(+)Treg cells; induction of suppressive cytokines, such as IL-10 and transforming growth factor β; suppression of allergen-specific IgE and induction of IgG4 and IgA; and suppression of mast cells, basophils, eosinophils, and inflammatory dendritic cells. This review summarizes the current knowledge on the mechanisms of allergen-SIT with emphasis on the roles of Treg cells in allergen-SIT.

Intestinal epithelial cells express galectin-9 in patients with food allergy that plays a critical role in sustaining allergic status in mouse intestine

BACKGROUND AND AIMS

Mechanisms in sustaining the allergic hypersensitivity status in the body are unclear. Galectin-9 (Gal-9) has strong immune regulatory capacity. The present study aims to elucidate the role of Gal-9 in sustaining allergic status in the intestine.

METHODS

Duodenal biopsies were obtained from 20 patients with peptic ulcer and food allergy (FA). The expression of Gal-9 in intestinal tissue was examined at both protein level and mRNA level. Two coculture systems with intestinal epithelial cells (IEC) and mast cells, or dendritic cells (DC) and T cells were established to investigate the source of Gal-9 in the intestine and the mechanism by which Gal-9 modulated DC's phenotyping and sustained the T helper 2 polarization.

RESULTS

Normal IEC showed mild expression of Gal-9 that was markedly enhanced in patients with FA. Mast cells had the capability to induce IEC to produce Gal-9 via releasing tryptase that activated the proteinase-activated receptor 2 on IEC. Gal-9 activated DC to produce TIM4 (T-cell immunoglobulin mucin domain) via ligating TIM3 on DC via activating the cyclic guanosine monophosphate (cGMP) pathway. In a mouse FA model, blocking Gal-9 inhibited the allergic hypersensitivity status and the antigen-specific Th2 response in the intestine.

CONCLUSIONS

IEC-derived Gal-9 contributes to sustaining the allergic status in the intestine.

Role of TIM-4 in innate or adaptive immune response

Human being living in constant contact with microbes and pathogen and in the process has developed a recognition pattern of pathogenic structure in the immune cells. The gut lumen has high density of microbes thus the immune response is slightly tolerable to certain microbes, known as commensal flora. These microbes along with other innocuous agents do not cause any inflammation response normally, and are considered as harmless by the immune cells. In immune hypersensitivity condition, such as colitis or food allergy, this mechanism is disturbed. T cell immunoglobulin and mucin domain (TIM)-4 is a phosphatidylserine receptor expressed in mature antigen presenting cells. It is shown that TIM-4 and its ligand TIM-1 are associated in intestinal immune response. However the characteristic of TIM-4 sometimes seems to be two-faced and there is a possibility that TIM-4 also bind to other ligands.

The crucial role of dendritic cells in rhinitis

PURPOSE OF REVIEW

Dendritic cells generally play an important role as sentinels in the immune system. They are also very important in protecting the airways from invading pathogens and harmful particles and antigens. This review discusses current knowledge about dendritic cell function and the interaction between dendritic cells and their surroundings, the epithelium, during their presence in the nasal mucosa.

RECENT FINDINGS

There are some phenotypical differences between myeloid dendritic cells and plasmacytoid dendritic cells in different types of rhinitis. Since it has become possible to perform functional studies on purified dendritic cell populations obtained from the upper airway mucosa, a number of studies have appeared. Some confirm that thymic stromal lymphopoietin is present in the nasal mucosa and that it may influence dendritic cell-T-cell interaction in a pro-Th2 way. Epithelial cells share several characteristics with dendritic cells, but they cannot migrate and move antigens to draining lymph nodes.

SUMMARY

Several functional dendritic cell studies have been published indicating that there are disease-dependent dendritic cell differences in rhinitis. In addition to these differences, factors like epithelial cells and T cells influence dendritic cells. Several new therapeutic options are available targeting direct or indirect dendritic cell functions.

TIM4 modulates antigen-specific Th2 cell differentiation in mice with food allergy

AIM: To evaluate the modulatory effect of microbial products on the expression of T cell immunoglobulin and mucin domain 4 (TIM4) in dendritic cells (DCs) and to determine the role of TIM4 in modulating CD4+ T cell activation in allergic response induced by exposure to microbial products.

METHODS: Bone marrow-derived DCs were isolated from Balb/c mice and cultured in vitro. Cultured DCs were divided into control group and Staphylococcal enterotoxin B (SEB)-stimulated group. The expression of TIM4 mRNA in different groups of DCs was measured by reverse transcription-polymerase chain reaction (RT-PCR). The expression of CD11c, MHC-II and CD86 on DCs were measured by flow cytometry. DCs co-cultured with CD4+ T cells in vitro were divided into five groups: control group, SEB group, OVA group, SEB plus ovalbumin (OVA) group, and anti-TIM4 antibody plus SEB and OVA group. Different sets of DCs were co-cultured for 48 h with CD4+ T cells that were obtained from the spleen of allergic mice. Levels of interleukin-4 (IL-4) and interferon-γ (IFN-γ) in culture medium were evaluated by enzyme-linked immunosorbent assay (ELISA).

RESULTS: Compared with the control group, the expression of TIM4 mRNA in DCs was increased significantly in the SEB-stimulated group (0.941 ± 0.018 vs 0.422 ± 0.083, P < 0.05), and SEB up-regulated the expression of TIM-4 in a dose-dependent manner. SEB stimulation also significantly increased the expression of MHC-II and the costimulatory molecule CD86 on DCs compared with control cells (MHC-II: 76.684% ± 3.1803% vs 52.984% ± 3.6026%, P = 0.000; CD86: 89.746% ± 2.113% vs 67.558% ± 0.4341%, P = 0.000). Compared with control DCs co-cultured with CD4+ T cells, the level of IL-4 in culture medium increased significantly (295.834 ± 20.408 vs 78.335 ± 13.109, P < 0.05) and that of IFN-γ decreased significantly (362.109 ± 92.271 vs 761.897 ± 102.967, P < 0.05) in the SEB plus OVA group. The levels of IL-4 and IFN-γ in the SEB group and OVA group showed no significant differences with those in the control group. In contrast, the expression level of IL-4 was significantly lower and that of IFN-γ was significantly higher in the anti-TIM4 antibody group than in the SEB plus OVA group (P < 0.05). The levels of IL-4 and IFN-γ in the anti-TIM4 antibody group showed no significant differences with those in the control group, SEB group and OVA group (90.511 ± 15.500 vs 295.834 ± 20.408; 807.734 ± 95.436 vs 362.109 ± 92.271, both P < 0.05).

CONCLUSION: TIM4 is involved in the pathogenesis of food allergy induced by concurrent exposure to microbial products and food antigen. Inhibition of TIM4 expression can significantly inhibit Th2 cell polarization, effectively correct Th1/Th2 imbalance and thereby prevent the development of allergic reaction.