Expression and release of IL-29 by mast cells and modulation of mast cell behavior by IL-29

Mast cell mediation of visceral sensation and permeability in irritable bowel syndrome

Abnormalities of mast cell structure or function may play prominent roles in irritable bowel syndrome (IBS) symptom genesis. Mast cells show close apposition to sensory nerves and release bioactive substances in response to varied stimuli including infection, stress, and other neuroendocrine factors. Most studies focus on patients who develop IBS after enteric infection or who report diarrhea-predominant symptoms. Three topics underlying IBS pathogenesis have been emphasized in recent investigations. Visceral hypersensitivity to luminal stimulation is found in most IBS patients and may contribute to abdominal pain. Mast cell dysfunction also may disrupt epithelial barrier function which alters mucosal permeability potentially leading to altered bowel function and pain. Mast cell products including histamine, proteases, prostaglandins, and cytokines may participate in hypersensitivity and permeability defects, especially with diarrhea-predominant IBS. Recent experimental evidence indicates that the pronociceptive effects of histamine and proteases are mediated by the generation of prostaglandins in the mast cell. Enteric microbiome interactions including increased mucosal bacterial translocation may activate mast cells to elicit inflammatory responses underlying some of these pathogenic effects. Therapies to alter mast cell activity (mast cell stabilizers) or function (histamine antagonists) have shown modest benefits in IBS. Future investigations will seek to define patient subsets with greater potential to respond to therapies that address visceral hypersensitivity, epithelial permeability defects, and microbiome alterations secondary to mast cell dysfunction in IBS.

The Role of Crosstalk of Immune Cells in Pathogenesis of Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is defined as recurrent episodes of spontaneous wheal development and/or angioedema for more than six weeks and at least twice a week. The core link in the pathogenesis of CSU is the activation of mast cells, T cells, eosinophils, and other immune cells infiltrating around the small venules of the lesion. Increased vascular permeability, vasodilatation, and recruitment of inflammatory cells directly depend on mast cell mediators’ release. Complex regulatory systems tightly influence the critical roles of mast cells in the local microenvironment. The bias toward Th2 inflammation and autoantibodies derived from B cells, histamine expressed by basophils, and initiation of the extrinsic coagulation pathway by eosinophils or monocytes exerts powerful modulatory influences on mast cells. Cell-to-cell interactions between mast cells and eosinophils/T cells also are regulators of their function and may involve CSU’s pathomechanism. This review summarizes up-to-date knowledge regarding the crosstalk between mast cells and other immune cells, providing the impetus to develop new research concepts and treatment strategies for CSU.

Enhanced serum interferon-lambda 1 interleukin-29 levels in patients with psoriasis vulgaris

BACKGROUND

Interferon (IFN)-λ1, also named Interleukin (IL)-29, is a new member of the Type III IFN or IFN-λ family. IL-29 plays an important role in the pathogenesis of many types of autoimmune and inflammatory diseases.

OBJECTIVE

To study the role of IL-29 in the pathogenesis of psoriasis vulgaris.

METHODS

The authors detected the serum levels of IL-29 in forty-one patients with psoriasis vulgaris, twenty-three patients with atopic dermatitis and thirty-eight age and gender-matched controls by sandwich Enzyme-Linked Immunosorbent Assay (ELISA). The effects of IL-29 on the expression of cytokines, such as IL-6, IL-17, IL-8, IL-4, IL10, Interferon (IFN-γ) and Tumor Necrosis Factor-α (TNF-α), in PBMCs and HaCat cells were determined by real-time quantitative PCR.

RESULTS

Our data indicated that serum IL-29 levels were significantly elevated in patients with psoriasis vulgaris when compared with atopic dermatitis patients and the control group. Moreover, Serum levels of IL-29 were closely associated with the severity of psoriasis vulgaris. Furthermore, IL-29 up-regulated the mRNA expression levels of IL-6, IL-17 and TNF-α in PBMCs from psoriasis vulgaris patients. In addition, IL-29 enhanced the IL-6 and IL-8 expression from the HaCat cells.

CONCLUSION

This study provides the first observations on the association of IL-29 and psoriasis vulgaris and showed elevated IL-29 serum levels. The authors suggest that IL-29 may play a role in the pathogenesis of psoriasis vulgaris.

Upregulated Expression of Toll-Like Receptor 7 in Peripheral Blood Basophils of Patients With Allergic Rhinitis

Background

Recently, it has been reported that Toll-like receptor 7 (TLR7) agonists can improve allergic rhinitis (AR) symptoms by up-regulation of Th1 cytokine release and suppression of Th2 cell functions. However, little is known of the expression of TLR7 in basophils of AR.

Objective

To explore the expression of TLR7 in basophils of AR, and influence of allergens on TLR7 expression.

Methods

The expression levels of TLR7 in basophils of patients with AR were determined by flow cytometry, and the influence of allergens on TLR7 expression was examined by real time (q) PCR.

Results

The percentages of TLR7+CCR3+ cells ( P < 0.001 and P = 0.011), TLR7+CD123+HLA-DR− cells ( P = 0 .016 and P = 0.042) and TLR7+CCR3+CD123+HLA-DR− cells ( P = 0.046 and P = 0.035) in blood granulocyte and mononucleated cell populations of the patients with AR were increased, respectively compared with HC subjects. TLR7 MFI on CCR3+ cells ( P = 0.050 and P = 0.043), CD123+HLA-DR− cells ( P < 0.001 and P = 0.002) and CCR3+CD123+HLA-DR− cells ( P < 0.001 and P = 0.003) were enhanced compared with HC subjects. Allergens Der p1 and OVA provoked upregulation of TLR7 expression at both protein and mRNA levels and IL-13 production in KU812 cells. House Dust Mite extract (HDME), Artemisia sieversiana wild allergen extract (ASWE), IL-31, IL-33, IL-37, and TSLP provoked elevation of IL-6 release from KU812 cells following 2 h incubation period.

Conclusions

The percentage of TLR7+ basophils and TLR7 expression intensity in a single basophil are both increased in the blood of patients with AR, indicating that basophils likely contribute to the pathogenesis of AR via TLR7.

Upregulation of the expression of Toll-like receptor 9 in basophils in patients with allergic rhinitis: An enhanced expression by allergens

It was reported that the expression of Toll-like receptor (TLR) 9 may be related to Th2-type allergic inflammation including allergic rhinitis (AR). However, little is known about the expression of TLR9 in the basophils in AR. In the present study, the expression of TLR9 was examined by flow cytometry analysis, and the expression of TLR9 mRNA in KU812 was determined by quantitative real-time PCR. The results showed that the percentage of TLR9⁺ CCR3⁺ cells in blood granulocytes increased by 46% in patients with AR, but not in peripheral blood mononuclear cells (PBMCs). Allergens namely Dermatophagoide allergen extract (DAE) and Platanus pollen allergen extract (PPAE) upregulated the expression of TLR9 in CCR3⁺ granulocytes by 76% and 84%, respectively. DAE and PPAE also enhanced the proportions of TLR9⁺ CD123⁺ HLA-DR^- cells and TLR9⁺ CCR3⁺ CD123⁺ HLA-DR^- cells in granulocytes and PBMCs of patients with AR. In order to investigate the actions of allergens on basophils, KU812 cells were used. It was observed that all KU812 cells expressed TLR9, and the expression intensity of TLR9 in a single KU812 cell was elevated by CpG. IL-37, IL-31, IL-33, Artemisia sieversiana wild allergen extract (ASWAE), DAE, OVA and Der p 1 induced an increase in the expression of TLR9 mRNA and IL-6 production in KU812 cells. It was shown that the percentage of TLR9-expressing basophils increased in the blood of ovalbumin (OVA)-sensitized mice. In conclusion, an increased expression of TLR9 and the production of IL-6 in basophils implicate that the contribution of basophils to AR is likely via TLR9.

Insights into IL-29: Emerging role in inflammatory autoimmune diseases

Interleukin-29 (IL-29) is a newly discovered member of type III interferon. It mediates signal transduction via binding to its receptor complex and activates downstream signalling pathways, and therefore induces the generation of inflammatory components. Recent studies reported that expression of IL-29 is dysregulated in inflammatory autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, osteoarthritis, Sjögren's syndrome, psoriasis and systemic sclerosis. Furthermore, functional analysis revealed that IL-29 may involve in the pathogenesis of the inflammatory autoimmune disorders. In this review, we will systematically review the current knowledge about IL-29. The information collected revealed the regulatory role of IL-29 and may give important implications for its potential in clinical treatment.

Chinese Society of Allergy Guidelines for Diagnosis and Treatment of Allergic Rhinitis

Allergic rhinitis (AR) is a global health problem that causes major illnesses and disabilities worldwide. Epidemiologic studies have demonstrated that the prevalence of AR has increased progressively over the last few decades in more developed countries and currently affects up to 40% of the population worldwide. Likewise, a rising trend of AR has also been observed over the last 2-3 decades in developing countries including China, with the prevalence of AR varying widely in these countries. A survey of self-reported AR over a 6-year period in the general Chinese adult population reported that the standardized prevalence of adult AR increased from 11.1% in 2005 to 17.6% in 2011. An increasing number of Journal Articles and imporclinical trials on the epidemiology, pathophysiologic mechanisms, diagnosis, management and comorbidities of AR in Chinese subjects have been published in international peer-reviewed journals over the past 2 decades, and substantially added to our understanding of this disease as a global problem. Although guidelines for the diagnosis and treatment of AR in Chinese subjects have also been published, they have not been translated into English and therefore not generally accessible for reference to non-Chinese speaking international medical communities. Moreover, methods for the diagnosis and treatment of AR in China have not been standardized entirely and some patients are still treated according to regional preferences. Thus, the present guidelines have been developed by the Chinese Society of Allergy to be accessible to both national and international medical communities involved in the management of AR patients. These guidelines have been prepared in line with existing international guidelines to provide evidence-based recommendations for the diagnosis and management of AR in China.

Induction of mast cell accumulation by chymase via an enzymatic activity- and intercellular adhesion molecule-1-dependent mechanism

BACKGROUND AND PURPOSE

Chymase is a unique, abundant secretory product of mast cells and a potent chemoattractant for eosinophils, monocytes and neutrophils, but little is known of its influence on mast cell accumulation.

EXPERIMENTAL APPROACH

A mouse peritoneal inflammation model, cell migration assay and flowcytometry analysis, were used to investigate the role of chymase in recruiting mast cells.

KEY RESULTS

Chymase increased, by up to 5.4-fold, mast cell numbers in mouse peritoneum. Inhibitors of chymase, heat-inactivation of the enzyme, sodium cromoglycate and terfenadine, and pretreatment of mice with anti-intercellular adhesion molecule 1, anti-L-selectin, anti-CD11a and anti-CD18 antibodies dramatically diminished the chymase-induced increase in mast cell accumulation. These findings indicate that this effect of chymase is dependent on its enzymatic activity and activation of adhesion molecules. In addition, chymase provoked a significant increase in 5-HT and eotaxin release (up to 1.8- and 2.2-fold, respectively) in mouse peritoneum. Since 5-HT, eotaxin and RANTES can induce marked mast cell accumulation, these indirect mechanisms may also contribute to chymase-induced mast cell accumulation. Moreover, chymase increased the trans-endothelium migration of mast cells in vitro indicating it also acts as a chemoattractant.

CONCLUSION AND IMPLICATIONS

The finding that mast cells accumulate in response to chymase implies further that chymase is a major pro-inflammatory mediator of mast cells. This effect of chymase, a major product of mast cell granules, suggests a novel self-amplification mechanism for mast cell accumulation in allergic inflammation. Mast cell stabilizers and inhibitors of chymase may have potential as a treatment of allergic disorders.

Enhanced Expression of IL-18 and IL-18BP in Plasma of Patients with Eczema: Altered Expression of IL-18BP and IL-18 Receptor on Mast Cells

IL-18 has been found to be associated with eczema. However, little is known of the role of IL-18 binding protein (BP) and IL-18 receptor (R) in eczema. We therefore investigated the expression of IL-18, IL-18BP, and IL-18R on mast cells by using flow cytometry analysis and mouse eczema model. The results showed that plasma free IL-18 and free IL-18BP levels in eczema patients were higher than those in healthy controls. IL-18 provoked up to 3.1-fold increase in skin mast cells. IL-18 induced also an increase in IL-18BP+ mast cells, but a reduction of IL-18R+ mast cells in mouse eczema skin. It was found that house dust mite allergen Der p1 and egg allergen OVA induced upregulation of the expression of IL-18, IL-18BP, and IL-18R mRNAs in HMC-1 cells following 2 and 16 h incubation. In conclusion, correlation of IL-18 and IL-18BP in eczema plasma suggests an important balance between IL-18 and IL-18BP in eczema. The decrease in molar concentration ratio of plasma IL-18BP/IL-18 and allergen-induced upregulated expression of IL-18 and IL-18R in skin mast cells of the patients with eczema suggests that anti-IL-18 including IL-18BP therapy may be useful for the treatment of eczema.

Unveil the mysterious mask of cytokine-based immunotherapy for melanoma

Melanoma is the leading cause of death among all skin cancers and its incidence continues to rise rapidly worldwide in the past decades. The available treatment options for melanoma remain limited despite extensive clinical research. Melanoma is an immunogenic tumor and great advances in immunology in recent decades allow for the development of immunotherapeutic agents against melanoma. In recent years, immunotherapy utilizing cytokines has been particularly successful in certain cancers and holds promise for patients with advanced melanoma. In this review, an overview of the current status and emerging perspectives on cytokine immunotherapy for melanoma are discussed in details. Such a study will be helpful to unveil the mysterious mask of cytokine-based immunotherapy for melanoma.

Elevated Serum Levels of Interleukin-29 Are Associated with Disease Activity in Rheumatoid Arthritis Patients with Anti-Cyclic Citrullinated Peptide Antibodies

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that may lead to progressive joint destruction. The anti-cyclic citrullinated peptide (anti-CCP) antibody is an essential marker for the diagnosis of RA and has a crucial role in the bone destruction in RA. Recent studies have shown that interleukin (IL)-29, a vital member of type III interferon (IFN) family, could enhance proinflammatory cytokine production and might be involved in the joint destruction in RA. Therefore, in this study, we aimed to examine the role of IL-29 in RA patients with anti-CCP antibodies. The result showed that the serum IL-29 levels were higher in RA patients (n = 68) compared with healthy controls (HC, n = 68, P = 0.019). Correlation analysis demonstrated a significant positive correlation among serum IL-29 level, rheumatoid factor (RF, P < 0.001) and anti-CCP antibodies (P = 0.042). However, when RA patients were divided into two groups according to anti-CCP antibodies, the serum IL-29 levels were significantly higher in anti-CCP-antibodies positive RA patients (n = 54) than those in HC (n = 68) and anti-CCP-antibodies negative RA patients (n = 14). Furthermore, the serum IL-29 levels were positively correlated with the disease activity (P < 0.05) and significantly declined after 6 months of treatment (P < 0.01) in the anti-CCP-antibodies positive RA patients, whereas no significant change was found in the anti-CCP-antibodies negative RA patients (P > 0.05). The findings indicate that IL-29 is a potential biomarker for disease activity in anti-CCP-antibodies positive RA patients.

The role of IL-29 in immunity and cancer

Interleukin-29 (IL-29) is a new member of the recently discovered interferon λ (IFNλ) family. It is produced predominantly by maturing dendritic cells and macrophages. It has been implicated in numerous immunological responses and has shown antiviral activity similar to the Type I interferons, although its target cell population is more limited than the Type I interferons. In recent years, the role of IL-29 in the pathogenesis of various cancers has also been extensively studied. In this review, we will discuss the recent advances of IL-29 in immunological processes and the pathogenesis of various cancer.

Ocular Fluid Analysis in Children Reveals Interleukin-29/Interferon-λ1 as a Biomarker for Juvenile Idiopathic Arthritis-Associated Uveitis

OBJECTIVE

Childhood uveitis is a vision-threatening inflammatory eye disease commonly attributed to juvenile idiopathic arthritis (JIA). The pathogenesis is poorly understood, which makes clinical management challenging. We analyzed soluble mediators in ocular fluid (aqueous humor [AqH]) and serum from children with JIA-associated uveitis and common childhood uveitis to identify potential biomarkers and investigate the ocular microenvironment of this sight-threatening eye disease.

METHODS

AqH (n = 73) and paired serum (n = 66) samples were analyzed for 51 soluble mediators of inflammation by multiplex immunoassay. Twenty-one children with JIA-associated uveitis were compared to 15 children with chronic anterior uveitis without arthritis, 29 children with noninfectious idiopathic uveitis, and 8 children with noninflammatory conditions (controls). For visualization of the joint effect of multiple mediators, we used the radial coordinate visualization (Radviz) method. Optimal biomarker level cutoffs were also determined.

RESULTS

The levels of interleukin-29 (IL-29)/interferon-λ1 (IFNλ1) were decreased (P < 0.001) and the levels of latency-associated peptide and osteoprotegerin were increased (P = 0.002 and P = 0.001, respectively) in samples of AqH, but not serum, from patients with JIA-associated uveitis. Multivariate analysis correcting for disease activity and treatment revealed that intraocular levels of IL-29/IFNλ1 were specifically decreased in patients with JIA-associated uveitis as compared to those with idiopathic uveitis. Indeed, JIA-associated uveitis patients and idiopathic uveitis patients showed distinct profiles of intraocular soluble mediators. IL-29/IFNλ1 showed a high area under the curve value (0.954), with 23.5 pg/ml as the optimal cutoff value.

CONCLUSION

We identified IL-29/IFNλ1 as an intraocular biomarker for JIA-associated uveitis, which suggests that aberrant IFNλ signaling might be important in JIA-associated uveitis and distinct from other forms of childhood uveitis.

Elevated Plasma Level of Interferon-λ1 in Chronic Spontaneous Urticaria: Upregulated Expression in CD8(+) and Epithelial Cells and Induction of Inflammatory Cell Accumulation

Interferon- (IFN-) λ1 is regarded as a potent bio-active molecule in innate immunity. However, little is known about its role in chronic spontaneous urticaria (CSU). We therefore investigated expression of IFN-λ1 in CSU, its cellular location, and its influence on inflammatory cell accumulation by using flow cytometry analysis, skin tissue dispersion, immunohistochemical stain, and a mouse peritoneal inflammation model. The results showed that level of IFN-λ1 was 2.0-fold higher in plasma of the patients with CSU than the level in healthy control (HC) subjects. Among leukocytes examined, only CD8(+) T cells expressed more IFN-λ1 in CSU blood. Double labeling immunohistochemical staining revealed that IFN-λ1(+) inflammatory cells such as mast cells, eosinophils, B cells, neutrophils, and macrophages were mainly located in dermis, whereas epidermis tissue highly expressed IFN-λ1. IFN-λ1 induced a dose-dependent increase in number of eosinophils, lymphocytes, mast cells, macrophages, and neutrophils in the peritoneum of mice at 6 h following injection, which was inhibited by pretreatment of the animals with anti-intercellular adhesion molecule- (ICAM-) 1 and/or anti-L-selectin antibodies. In conclusion, IFN-λ1 is likely to play a role in the pathogenesis of CSU. Blocking IFN-λ1 production may help to reduce the accumulation of inflammatory cells in the involved CSU skin.

Interleukin-29 Enhances Synovial Inflammation and Cartilage Degradation in Osteoarthritis

We have recently shown that IL-29 was an important proinflammatory cytokine in pathogenesis of rheumatoid arthritis (RA). Inflammation also contributes to the pathogenesis of osteoarthritis (OA). The aim of this study was to investigate the effect and mechanism of IL-29 on cytokine production and cartilage degradation in OA. The mRNA levels of IL-29 and its specific receptor IL-28Ra in peripheral blood mononuclear cells (PBMCs) were significantly increased in OA patients when compared to healthy controls (HC). In the serum, IL-29 protein levels were higher in OA patients than those in HC. Immunohistochemistry revealed that both IL-29 and IL-28Ra were dramatically elevated in OA synovium compared to HC; synovial fibroblasts (FLS) and macrophages were the main IL-29-producing cells in OA synovium. Furthermore, recombinant IL-29 augmented the mRNA expression of IL-1β, IL-6, IL-8, and matrix-metalloproteinase-3 (MMP-3) in OA FLS and increased cartilage degradation when ex vivo OA cartilage explant was coincubated with OA FLS. Finally, in OA FLS, IL-29 dominantly activated MAPK and nuclear factor-κB (NF-κB), but not Jak-STAT and AKT signaling pathway as examined by western blot. In conclusion, IL-29 stimulates inflammation and cartilage degradation by OA FLS, indicating that this cytokine is likely involved in the pathogenesis of OA.

Correlation of IL-18 with Tryptase in Atopic Asthma and Induction of Mast Cell Accumulation by IL-18

Interleukin- (IL-) 18 and tryptase were previously reported to relate to asthma, but the correlation between these two potent proinflammatory molecules in asthma and their roles in mast cell accumulation remain uninvestigated. Using flow cytometric analysis technique and ovalbumin- (OVA-) sensitized mouse model, it was found that IL-18 and tryptase levels in the plasma of moderate and severe asthma were elevated, and they correlated well with each other. Tryptase and agonist peptides of protease activated receptor- (PAR-) 2 induced substantial quantity of IL-18 release. IL-18 and tryptase provoked mast cell accumulation in peritoneum of OVA-sensitized mice. OVA-sensitization increased number of IL-18 receptor (R)⁺ mast cells. IL-18 and tryptase induced dramatic increase in IL-18R⁺ mast cells and mean fluorescence intensity (MFI) of IL-18R on mast cells. Moreover, while IL-18 induced an increase in PAR-2⁺ mast cells in nonsensitized mice, IL-18 and tryptase provoked increases in IL-4 and thymic stromal lymphopoietin (TSLP) in the peritoneum of OVA-sensitized mice. In summary, the correlation between IL-18 and tryptase in plasma of patients with asthma indicates close interactions between them, which should be considered for development of anti-IL-18 and antitryptase therapies. Interactions between IL-18 and tryptase may contribute to mast cell recruitment in asthma.

Altered Expression of IFN-λ2 in Allergic Airway Disorders and Identification of Its Cell Origins

This study investigated the expression levels of interferon- (IFN-) λ2 in peripheral blood and tissues. The results showed that the levels of IFN-λ2 were elevated by 17.9% and 14.2% in the plasma of allergic rhinitis (AR) and combined rhinitis with asthma (AR + AS), which was positively correlated with the level of tryptase but negatively correlated with the level of IL-10. IFN-λ2 was predominately expressed in the CD16+ cells and CD14+ cells in healthy control subjects (HC) but upregulated only in CD8+ cells of AR and in eosinophils of asthma. It was observed that approximately 6.6% and 7.0% dispersed tonsil cells and 5.8% and 0.44% dispersed lung cells are IFN-λ2+ mast cells and macrophages. Moreover, tryptase and agonist peptides of PAR-2 induced enhanced IFN-λ2 mRNA expression in A549 cells. In conclusion, the elevated levels of IFN-λ2 in the plasma of AR and AR + AS indicate that IFN-λ2 is likely to contribute to the pathogenesis of allergic airway disorders. The potential origins of the elevated plasma IFN-λ2 include mast cells, macrophages, and epithelial cells in tissues, neutrophils, monocytes, CD8+ T cells, and eosinophils in peripheral blood. Development of IFN-λ2 related therapy may help to treat or prevent allergic airway disorders.

Induction of Mast Cell Accumulation by Tryptase via a Protease Activated Receptor-2 and ICAM-1 Dependent Mechanism

Mast cells are primary effector cells of allergy, and recruitment of mast cells in involved tissue is one of the key events in allergic inflammation. Tryptase is the most abundant secretory product of mast cells, but little is known of its influence on mast cell accumulation. Using mouse peritoneal model, cell migration assay, and flow cytometry analysis, we investigated role of tryptase in recruiting mast cells. The results showed that tryptase induced up to 6.7-fold increase in mast cell numbers in mouse peritoneum following injection. Inhibitors of tryptase, an antagonist of PAR-2 FSLLRY-NH2, and pretreatment of mice with anti-ICAM-1, anti-CD11a, and anti-CD18 antibodies dramatically diminished tryptase induced mast cell accumulation. On the other hand, PAR-2 agonist peptides SLIGRL-NH2 and tc-LIGRLO-NH2 provoked mast cell accumulation following injection. These implicate that tryptase induced mast cell accumulation is dependent on its enzymatic activity, activation of PAR-2, and interaction between ICAM-1 and LFA-1. Moreover, induction of trans-endothelium migration of mast cells in vitro indicates that tryptase acts as a chemoattractant. In conclusion, provocation of mast cell accumulation by mast cell tryptase suggests a novel self-amplification mechanism of mast cell accumulation. Mast cell stabilizers as well as PAR-2 antagonist agents may be useful for treatment of allergic reactions.

Indication of immune activation in patients with perceived food hypersensitivity

Majority of the patients with perceived food hypersensitivity have irritable bowel syndrome (IBS), and a significant proportion of IBS patients also attribute their gastrointestinal complaints to food items. Different factors such as disturbed intestinal fermentation, enteric dysmotility, post-infectious changes and altered microbial flora in the colon as well as psychological disturbances likely play a role in the pathophysiology and symptoms generation in patients with food hypersensitivity. In addition, a number of studies in these patient groups indicate that local, systemic and mucosal immune systems are activated. The question now is no longer intestinal immune activation, but how the immune system is activated in these patients. In the following review, the potential pathogenetic role of the immune system and evidence of immune activation are reported in patients with perceived food hypersensitivity.

IL-29 enhances Toll-like receptor-mediated IL-6 and IL-8 production by the synovial fibroblasts from rheumatoid arthritis patients

INTRODUCTION

We previously reported that IL-29, a newly described member of interferon (IFN) family, was overexpressed in blood and synovium of rheumatoid arthritis (RA) patients and triggered proinflammatory cytokine IL-6 and IL-8 mRNA expression in RA synovial fibroblasts (RA-FLS). This suggests that IL-29 has an important role in synovial inflammation. Toll-like receptors (TLRs) also activate RA-FLS to produce inflammatory mediators including tumor necrosis factor α (TNF-α) and IL-1β in RA-FLS. Since the TLR family plays an early role in the innate immune response and the subsequent induction of the adaptive immune response, we hypothesize that IL-29 interacts with TLRs in RA inflammation. This study aimed to investigate the effect of IL-29 on TLR-mediated proinflammatory cytokine production in RA-FLS.

METHODS

The mRNA level of IL-29 receptors (IL-28Rα and IL-10R2) in RA-FLS was determined by semi-quantitative RT- PCR. IL-6 and IL-8 mRNA expressions in RA-FLS were evaluated by real-time PCR after pre-incubation with IL-29 and subsequent stimulation with peptidoglycan (PGN, TLR2 ligand), or polycytidylic acid (poly(I:C), TLR3 ligand), or lipopolysaccharide (LPS, TLR4 ligand) . The production of TLR2, 3, and 4 in RA-FLS after IL-29 stimulation was also assessed by real-time PCR and flow cytometry. IL-29 mRNA and protein expression in RA-FLS after stimulation with PGN, poly(I:C), or LPS were measured by real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

The IL-29 receptor complex (IL-28Rα and IL-10R2) was identified in RA-FLS. IL-29 enhanced TLR-mediated IL-6 and IL-8 expression in RA-FLS. IL-29 upregulated expression of TLR2, 3 and 4 in RA-FLS. Exposure to PGN, poly(I:C) or LPS triggered IL-29 production by RA-FLS.

CONCLUSIONS

We show for the first time that IL-29 enhances TLR-induced proinflammatory cytokine production in RA-FLS via upregulation of TLRs.

Mast cells and basophils are essential for allergies: mechanisms of allergic inflammation and a proposed procedure for diagnosis

The current definition of allergy is a group of IgE-mediated diseases. However, a large portion of patients with clinical manifestations of allergies do not exhibit elevated serum levels of IgE (sIgEs). In this article, three key factors, ie soluble allergens, sIgEs and mast cells or basophils, representing the causative factors, messengers and primary effector cells in allergic inflammation, respectively, were discussed. Based on current knowledge on allergic diseases, we propose that allergic diseases are a group of diseases mediated through activated mast cells and/or basophils in sensitive individuals, and allergic diseases include four subgroups: (1) IgE dependent; (2) other immunoglobulin dependent; (3) non-immunoglobulin mediated; (4) mixture of the first three subgroups. According to our proposed definition, pseudo-allergic-reactions, in which mast cell or basophil activation is not mediated via IgE, or to a lesser extent via IgG or IgM, should be non-IgE-mediated allergic diseases. Specific allergen challenge tests (SACTs) are gold standard tests for diagnosing allergies in vivo, but risky. The identification of surface membrane activation markers of mast cells and basophils (CD203c, CCR3, CD63, etc) has led to development of the basophil activation test (BAT), an in vitro specific allergen challenge test (SACT). Based on currently available laboratory allergy tests, we here propose a laboratory examination procedure for allergy.

Modulation of PAR expression and tryptic enzyme induced IL-4 production in mast cells by IL-29

Interleukin (IL)-29 is a relatively newly discovered cytokine, which has been shown to be actively involved in the pathogenesis of allergic inflammation. However, little is known of the effects of IL-29 on protease activated receptor (PAR) expression and potential mechanisms of cytokine production in mast cells. In the present study, we examined potential influence of IL-29 on PAR expression and cytokine production in P815 and bone marrow derived mast cells (BMMCs) by using flow cytometry analysis, quantitative real time PCR, and ELISA techniques. The results showed that IL-29 downregulated the expression of PAR-1 by up to 56.2%, but had little influence on the expression of PAR-2, PAR-3 and PAR-4. IL-29 also induced downregulation of expression of PAR-1 mRNA. However, when mast cells were pre-incubated with IL-29, thrombin-, trypsin- and tryptase-induced expression of PAR-2, PAR-3 and PAR-4 was upregulated, respectively. IL-29 provoked approximately up to 1.9-fold increase in IL-4 release when mast cells was challenged with IL-29. Administration of IL-29 blocking antibody, AG490 or LY294002 abolished IL-29-induced IL-4 release from P815 cells. It was found that IL-29 diminished trypsin- and tryptase-induced IL-4 release from P815 cells following 16 h incubation. In conclusion, IL-29 can regulate expression of PARs and tryptase- and trypsin-induced IL-4 production in mast cells, through which participates in the mast cell related inflammation.

Interferon-λs: special immunomodulatory agents and potential therapeutic targets

Interferon (IFN)-λs are a new addition to the old IFN family and share many similarities, such as antiviral and antiproliferative characteristics, with type I IFNs. IFN-λs also exhibit unique characteristics in immunomodulation. Accumulating studies have indicated the interactions between IFN-λs and immune cells, which lead to the regulation of the latter. IFN-λs can influence dendritic cells (DCs) and their product, IFN-λs-DCs, can then regulate the function of T cells. On the other hand, IFN-λs can also directly affect T cells through inhibition of the T helper 2 cell (Th2) responses. IFN-λs have varying immunomodulatory functions under different physiological conditions or in different organs and can inhibit tumor growth via regulation of the immune system. Diseases associated with IFN-λs include asthma, allergy, and systemic lupus erythematosus. In this review, we summarize the current knowledge of the biology of IFN-λs and their immunomodulatory function in relevant human diseases.

Mast cells

Mast cells have been considered for many years to participate specifically in allergic reactions through the release of cytokines, chemokines, proteases, leukotrienes, and bioactive polyamines. Emerging roles for mast cells have been identified recently, which highlight their relevance in both innate and adaptive immunity. Mast cells play a role in many different processes, including clearance of enteric pathogens, food allergies, visceral hypersensitivity, and intestinal cancer. The activation of mast cells can initiate inflammatory reactions that are life-saving in some circumstances (eg, nematode infection) but life-threatening in others (eg, allergy). In recent years, mast cells, their products, and the mechanisms by which mast cell activity can be regulated by the microenvironment are a major area of investigation. The purpose of this review article is to summarize and highlight the latest findings in mast cell biology associated with intestinal homeostasis and pathologies.