IL-31-IL-31R interactions limit the magnitude of Th2 cytokine-dependent immunity and inflammation following intestinal helminth infection

Atopic dermatitis and food allergy: More than sensitization

The increased risk of food allergy in infants with atopic dermatitis (AD) has long been recognized; an epidemiologic phenomenon termed "the atopic march." Current literature supports the hypothesis that food antigen exposure through the disrupted skin barrier in AD leads to food antigen-specific immunoglobulin E production and food sensitization. However, there is growing evidence that inflammation in the skin drives intestinal remodeling via circulating inflammatory signals, microbiome alterations, metabolites, and the nervous system. We explore how this skin-gut axis helps to explain the link between AD and food allergy beyond sensitization.

Genomic Regions Associated with Resistance to Gastrointestinal Nematode Parasites in Sheep-A Review

Gastrointestinal nematodes (GINs) can be a major constraint and global challenge to the sheep industry. These nematodes infect the small intestine and abomasum of grazing sheep, causing symptoms such as weight loss, diarrhea, hypoproteinemia, and anemia, which can lead to death. The use of anthelmintics to treat infected animals has led to GIN resistance, and excessive use of these drugs has resulted in residue traced in food and the environment. Resistance to GINs can be measured using multiple traits, including fecal egg count (FEC), Faffa Malan Chart scores, hematocrit, packed cell volume, eosinophilia, immunoglobulin (Ig), and dagginess scores. Genetic variation among animals exists, and understanding these differences can help identify genomic regions associated with resistance to GINs in sheep. Genes playing important roles in the immune system were identified in several studies in this review, such as the CFI and MUC15 genes. Results from several studies showed overlapping quantitative trait loci (QTLs) associated with multiple traits measuring resistance to GINs, mainly FEC. The discovery of genomic regions, positional candidate genes, and QTLs associated with resistance to GINs can help increase and accelerate genetic gains in sheep breeding programs and reveal the genetic basis and biological mechanisms underlying this trait.

IL-31-dependent neurogenic inflammation restrains cutaneous type 2 immune response in allergic dermatitis

Despite robust literature associating IL-31 with pruritic inflammatory skin diseases, its influence on cutaneous inflammation and the interplay between inflammatory and neurosensory pathways remain unmapped. Here, we examined the consequences of disrupting Il31 and its receptor Il31ra in a mouse model of house dust mite (HDM)-induced allergic dermatitis. Il31-deficient mice displayed a deficit in HDM dermatitis-associated scratching, consistent with its well-established role as a pruritogen. In contrast, Il31 deficiency increased the number and proportion of cutaneous type 2 cytokine-producing CD4+ T cells and serum IgE in response to HDM. Furthermore, Il4ra+ monocytes and macrophages capable of fueling a feedforward type 2 inflammatory loop were selectively enriched in Il31ra-deficient HDM dermatitis skin. Thus, IL-31 is not strictly a proinflammatory cytokine but rather an immunoregulatory factor that limits the magnitude of type 2 inflammatory responses in skin. Our data support a model wherein IL-31 activation of IL31RA+ pruritoceptors triggers release of calcitonin gene-related protein (CGRP), which can mediate neurogenic inflammation, inhibit CD4+ T cell proliferation, and reduce T cell production of the type 2 cytokine IL-13. Together, these results illustrate a previously unrecognized neuroimmune pathway that constrains type 2 tissue inflammation in the setting of chronic cutaneous allergen exposure and may explain paradoxical dermatitis flares in atopic patients treated with anti-IL31RA therapy.

Bone Involvement in Rheumatoid Arthritis and Spondyloartritis: An Updated Review

Several rheumatologic diseases are primarily distinguished by their involvement of bone tissue, which not only serves as a mere target of the condition but often plays a pivotal role in its pathogenesis. This scenario is particularly prominent in chronic inflammatory arthritis such as rheumatoid arthritis (RA) and spondyloarthritis (SpA). Given the immunological and systemic nature of these diseases, in this review, we report an overview of the pathogenic mechanisms underlying specific bone involvement, focusing on the complex interactions that occur between bone tissue's own cells and the molecular and cellular actors of the immune system, a recent and fascinating field of interest defined as osteoimmunology. Specifically, we comprehensively elaborate on the distinct pathogenic mechanisms of bone erosion seen in both rheumatoid arthritis and spondyloarthritis, as well as the characteristic process of aberrant bone formation observed in spondyloarthritis. Lastly, chronic inflammatory arthritis leads to systemic bone involvement, resulting in systemic bone loss and consequent osteoporosis, along with increased skeletal fragility.

IL-31: State of the Art for an Inflammation-Oriented Interleukin

Interleukin 31 belongs to the IL-6 superfamily, and it is an itch mediator already studied in several diseases, comprising atopic dermatitis, allergic pathologies, and onco-hematological conditions. This research aims to assess the role of this cytokine in the pathogenesis of these conditions and its potential therapeutic role. The research has been conducted on articles, excluding reviews and meta-analysis, both on animals and humans. The results showed that IL-31 plays a crucial role in the pathogenesis of systemic skin manifestations, prognosis, and itch severity. Traditional therapies target this interleukin indirectly, but monoclonal antibodies (Mab) directed against it have shown efficacy and safety profiles comparable with biological drugs that are already available. Future perspectives could include the development of new antibodies against IL-31 both for humans and animals, thus adding a new approach to the therapy, which often has proven to be prolonged and specific for each patient.

New insights into IL-6 family cytokines in metabolism, hepatology and gastroenterology

IL-6 family cytokines are defined by the common use of the signal-transducing receptor chain glycoprotein 130 (gp130). Increasing evidence indicates that these cytokines are essential in the regulation of metabolic homeostasis as well as in the pathophysiology of multiple gastrointestinal and liver disorders, thus making them attractive therapeutic targets. Over the past few years, therapies modulating gp130 signalling have grown exponentially in several clinical settings including obesity, cancer and inflammatory bowel disease. A newly engineered gp130 cytokine, IC7Fc, has shown promising preclinical results for the treatment of type 2 diabetes, obesity and liver steatosis. Moreover, drugs that modulate gp130 signalling have shown promise in refractory inflammatory bowel disease in clinical trials. A deeper understanding of the main roles of the IL-6 family of cytokines during homeostatic and pathological conditions, their signalling pathways, sources of production and target cells will be crucial to the development of improved treatments. Here, we review the current state of the role of these cytokines in hepatology and gastroenterology and discuss the progress achieved in translating therapeutics targeting gp130 signalling into clinical practice.

Trichuris muris and comorbidities - within a mouse model context

Trichuris muris is a mouse intestinal parasitic nematode that inhabits the large intestine of its host and induces a strong immune response. The effects of this strong anti-parasite response can be found locally within the intestinal niche and also systemically, having effects on multiple organs. Additionally, the anti-parasite response can have multiple effects on infectious organisms and on microbiota that the host is harbouring. It has been shown that Th1 responses induced by T. muris can affect progression of bowel inflammation, cause colitic-like intestinal inflammation, reduce barrier function and intestinal mucosal responses. In the brain, T. muris can exacerbate stroke outcome and other neurological conditions. In the lung, T. muris can suppress airway inflammation and alter immune responses to other parasites. Additionally, T. muris induced responses can inhibit anti-tumour immunity. Although this parasite maintains a localized niche in the large intestine, its effects can be far-reaching and substantially impact other infections through modulation of bystander immune responses.

Interleukin-31 Signaling Bridges the Gap Between Immune Cells, the Nervous System and Epithelial Tissues

Pruritus represents one of the most common symptoms in dermatology and general medicine. Chronic pruritus severely impairs the quality of life of affected patients. During the last two decades a number of modulators and mediator of pruritus have been identified. Recently, Interleukin (IL)-31 and its receptor complex attracted significant interest, as clinical phase two studies demonstrated therapeutic efficacy of the neutralizing IL-31 receptor A (IL-31RA) antibody nemolizumab in patients suffering from atopic dermatitis or prurigo nodularis. IL-31 has also been shown to play relevant roles in allergic contact dermatitis, urticaria, mastocytosis, allergic rhinitis and asthma. Here, we summarize the current knowledge of the novel cytokine IL-31 and its receptor regarding cellular origin, regulation, signaling pathways and their involvement in biological processes such as pruritus, neuronal growth, inflammation, barrier dysfunction and tissue remodeling.

IL-31 transgenic mice show reduced allergen-induced lung inflammation

Interleukin-31 (IL-31) is a Th2 cell-derived cytokine that has been closely linked to pruritic skin inflammation. More recently, enhanced IL-31 serum levels have also been observed in patients with allergic rhinitis and allergic asthma. Therefore, the main aim of this study was to unravel the contribution of IL-31 to allergen-induced lung inflammation. We analyzed lung inflammation in response to the timothy grass (Phleum pratense) pollen allergen Phl p 5 in C57BL/6 wild-type (wt) mice, IL-31 transgenic (IL-31tg) mice, and IL-31 receptor alpha-deficient animals (IL-31RA-/- ). IL-31 and IL-31RA levels were monitored by qRT-PCR. Cellular infiltrate in bronchoalveolar lavage fluid (BALF) and lung tissue inflammation, mucus production as well as epithelial thickness were measured by flow cytometry and histomorphology. While allergen challenge induced IL-31RA expression in lung tissue of wt and IL-31tg mice, high IL-31 expression was exclusively observed in lung tissue of IL-31tg mice. Upon Phl p 5 challenge, IL-31tg mice showed reduced numbers of leukocytes and eosinophils in BALF and lung tissue as well as diminished mucin expression and less pronounced epithelial thickening compared to IL-31RA-/- or wt animals. These findings suggest that the IL-31/IL-31RA axis may regulate local, allergen-induced inflammation in the lungs.

Interleukin-31, a Potent Pruritus-Inducing Cytokine and Its Role in Inflammatory Disease and in the Tumor Microenvironment

Substantial new information has emerged supporting the fundamental role of the cytokine interleukin-31 (IL-31) in the genesis of chronic pruritus in a broad array of clinical conditions. These include inflammatory conditions, such as atopic dermatitis and chronic urticaria, to autoimmune conditions such as dermatomyositis and bullous pemphigoid, to the lymphoproliferative disorders of Hodgkin's disease and cutaneous T-cell lymphoma. IL-31 is produced in greatest quantity by T-helper type 2 (Th2) cells and upon release, interacts with a cascade of other cytokines and chemokines to lead to pruritus and to a proinflammatory environment, particularly within the skin. Antibodies which neutralize IL-31 or which block the IL-31 receptor may reduce or eliminate pruritus and may diminish the manifestations of chronic cutaneous conditions associated with elevated IL-31. The role of IL-31 in these various conditions will be reviewed.

IL-33/IL-31 Axis in Osteoporosis

The study of the immunoskeletal interface has led to the discovery of numerous cytokines involved in the regulation of bone remodeling, providing valuable information on the pathogenesis of osteoporosis. The role of inflammatory cytokines of the Th1 and Th17 profile in osteoporosis is well known. Here we focus on two newly discovered Th2 cytokines, IL-31 and IL-33, whose implications in osteoporosis are recently emerging. Clinical and experimental observations suggest an important role of the IL-33/IL-31 axis in osteoporosis. IL-33 induces IL-31 secretion by Th2 cells and inhibits RANKL-dependent osteoclastogenesis, thus counteracting bone loss. IL-31 influences Th1/Th17 osteoclastogenetic inflammation and limits Th2 osteoprotective processes, thus favoring osteoporosis. Better knowledge of the role of IL-31 and IL-33 and their receptor complexes in osteoporosis could provide an interesting perspective for the development of new and more effective therapies, possibly with less side effects.

IL-31 plays dual roles in lung inflammation in an OVA-induced murine asthma model

Interleukin 31 (IL-31) is a four-helix cytokine made predominantly by Th2 CD4⁺ T cells. It was initially identified as being associated with the promotion of atopic dermatitis, where increased levels of IL-31 levels have been found and IL-31 induced the expression of proinflammatory cytokines and chemokines in a human bronchial epithelial cell line. However, subsequent study has shown that IL-31RA knockout mice developed exacerbated type 2 inflammation in the lung following infection with Schistosoma mansoni eggs. In this study, we investigated the dynamic expression of IL-31 and IL-31RA during eight consecutive ovalbumin (OVA) challenges and measured the chemokines from lung alveolar epithelial cells induced by IL-31. In addition, we examined the effect deletion of IL-31RA has on lung inflammation and the differentiation of CD4⁺ T cells. Our results demonstrate that the expression of IL-31 and IL-31RA was elevated after each weekly OVA challenge, although slightly less of both observed after the first week of OVA challenge. IL-31 also promoted the expression of inflammatory chemokines CCL5, CCL6, CCL11, CCL16, CCL22, CCL28, CX3CL1, CXCL3, CXCL14 and CXCL16 in alveolar epithelial cells. Migration of macrophages and T cells was enhanced by culture supernatants of IL-31-stimulated alveolar epithelial cells. Lastly, and in contrast to the IL-31 results, mice deficient in IL-31RA developed exacerbated lung inflammation, increased IL-4-positive cell infiltrates and elevated Th2 cytokine responses in draining lymph nodes. The proliferation of IL-31RA^-/- CD4⁺ T cells was enhanced in vitro after anti-CD3/anti-CD28 antibody stimulation. These data indicate that IL-31/IL-31RA may play dual roles, first as an early inflammatory mediator promoting the secretion of chemokines to recruit inflammatory cells, and subsequently as a late inflammatory suppressor, limiting Th2 cytokine responses in allergic asthma.

Revisiting the Concept of Targeting NFAT to Control T Cell Immunity and Autoimmune Diseases

The nuclear factor of activated T cells (NFAT) family of transcription factors, which includes NFAT1, NFAT2, and NFAT4, are well-known to play important roles in T cell activation. Most of NFAT proteins are controlled by calcium influx upon T cell receptor and costimulatory signaling results increase of IL-2 and IL-2 receptor. NFAT3 however is not shown to be expressed in T cells and NFAT5 has not much highlighted in T cell functions yet. Recent studies demonstrate that the NFAT family proteins involve in function of lineage-specific transcription factors during differentiation of T helper 1 (Th1), Th2, Th17, regulatory T (Treg), and follicular helper T cells (Tfh). They have been studied to make physical interaction with the other transcription factors like GATA3 or Foxp3 and they also regulate Th cell signature gene expressions by direct binding on promotor region of target genes. From last decades, NFAT functions in T cells have been targeted to develop immune modulatory drugs for controlling T cell immunity in autoimmune diseases like cyclosporine A, FK506, etc. Due to their undesirable side defects, only limited application is available in human diseases. This review focuses on the recent advances in development of NFAT targeting drug as well as our understanding of each NFAT family protein in T cell biology. We also discuss updated detail molecular mechanism of NFAT functions in T cells, which would lead us to suggest an idea for developing specific NFAT inhibitors as a therapeutic drug for autoimmune diseases.

Epithelial barrier dysfunctions in atopic dermatitis: a skin-gut-lung model linking microbiome alteration and immune dysregulation

BACKGROUND

Atopic dermatitis is a systemic disorder characterized by abnormal barrier function across multiple organ sites. Causes of epidermal barrier breakdown are complex and driven by a combination of structural, genetic, environmental and immunological factors. In addition, alteration in microflora diversity can influence disease severity, duration, and response to treatment. Clinically, atopic dermatitis can progress from skin disease to food allergy, allergic rhinitis, and later asthma, a phenomenon commonly known as the atopic march. The mechanism by which atopic dermatitis progresses towards gastrointestinal or airway disease remains to be elucidated.

OBJECTIVES

This review addresses how epithelial dysfunction linking microbiome alteration and immune dysregulation can predispose to the development of the atopic march.

METHODS

A literature search was conducted using the PubMed database for relevant articles with the keywords 'atopic dermatitis', 'epithelial barrier', 'skin', 'gut', 'lung', 'microbiome' and 'immune dysregulation'.

RESULTS

Initial disruption in the skin epidermal barrier permits allergen sensitization and colonization by pathogens. This induces a T helper 2 inflammatory response and a thymic stromal lymphopoietin-mediated pathway that further promotes barrier breakdown at distant sites, including the intestinal and respiratory tract.

CONCLUSIONS

As there are no immediate cures for food allergy or asthma, early intervention aimed at protecting the skin barrier and effective control of local and systemic inflammation may improve long-term outcomes and reduce allergen sensitization in the airway and gut.

The Role of Interleukin-31 Polymorphisms in Non-Small Cell Lung Cancer Genetic Susceptibility and Clinical Outcome

BACKGROUND

Interleukin-31 (IL-31), a novel T helper type 2 effector cytokine, is known to have an important effect on the pathogenesis of allergic disease and tumors. However, the impact of IL-31 on human lung cancer remains unclear.

METHODS

This study explored the role of IL-31 polymorphisms in lung cancer and sought to characterize how IL-31 polymorphisms correlate with lung cancer tumorigenesis and patient survival rates. Using a single-nucleotide polymorphism genotype assay, we examined the expression of two IL-31 polymorphisms (rs7977932 and rs4758680) in samples from 302 lung cancer patients and 493 control cases.

RESULTS

Lung cancer patients who were homozygous CC for rs7977932 or carried the G allele of rs4758680 had significantly poorer prognoses compared to those who did not have these genotypes. Moreover, the rs7977932 CC genotype was significantly associated with metastasis and poor survival status in lung adenocarcinoma.

CONCLUSION

Our study indicates the importance of IL-31 polymorphisms for susceptibility and survival status in lung cancer.

Effect of interleukin-31 on septic shock through regulating inflammasomes and interleukin-1β

Sepsis with severe systemic inflammation remains a great challenge for the intensive care unit in clinics. Although biomarkers have been identified to diagnose, monitor and predict these syndromes, novel therapeutic approaches are required for the amelioration of symptoms of sepsis and septic shock. The present study demonstrated that interleukin (IL)-31 was able reduce the mortality rate of lipopolysaccharide (LPS)-induced sepsis with the reduction of inflammatory cytokines in the sera. IL-31 also inhibited IL-1β production in the peritoneal lavage fluid in LPS-induced or cecal ligation and puncture-induced sepsis. The in vitro mechanism responsible for IL-31 regulation on peritoneal IL-1β activation following LPS challenge was explored. It was demonstrated that IL-1β secretion was suppressed by IL-31 treatment from LPS-challenged peritoneal macrophages following adenosine triphosphate stimulation, which is an activator of NLR family, pyrin domain-containing 3 (NLRP3). Furthermore, IL-31 inhibited the expression of NLRP3 at the transcriptional level. In human THP-1 cells, anti-IL-31/anti-IL-31 receptor (R) neutralizing antibody enhanced NLRP3 expression as well as IL-1β activation, suggesting a role of the IL-31-IL-31R-NLRP3-IL-1β signaling axis in the physiological status of sepsis. On the other hand, IL-31 displayed a negative effect on the NLRP1 inflammasome, but not on NLRP3 on the LPS-primed human peripheral blood monocytes, resulting in reduction of the inflammatory cytokine, tumor necrosis factor (TNF)-α, in the supernatant. Taken together, the present data implied that T helper 2-type cytokine, IL-31, may be a promising therapeutic option for treatment of sepsis and septic shock in clinics.

Increase In Il-31 Serum Levels Is Associated With Reduced Structural Damage In Early Axial Spondyloarthritis

In spondyloarthritis, little is known about the relation between circulating cytokines and patient phenotype. We have quantified serum levels of T helper type 1 cell (Th1), Th2 and Th17 cytokines in patients with recent-onset axial spondyloarthritis (AxSpA) from the DESIR cohort, a prospective, multicenter French cohort consisting of 708 patients with recent-onset inflammatory back pain (duration >3 months but <3 years) suggestive of AxSpA. Serum levels of Th1, Th2, and Th17 cytokines were assessed at baseline in patients from the DESIR cohort fulfilling the ASAS criteria (ASAS+) and were compared with age- and sex-matched healthy controls. At baseline, ASAS+ patients (n = 443) and healthy controls (n = 79) did not differ in levels of most of the Th1, Th2 and Th17 cytokines except for IL-31, and sCD40L, which were significantly higher for ASAS+ patients than controls (p < 0.001 and p = 0.012, respectively). On multivariable analysis of ASAS+ patients, IL-31 level was associated with sCD40L level (p < 0.0001), modified Stoke AS Spine Score (mSASSS) < 1 (p = 0.035). The multivariable analyses showed that IL-31 was an independent factor associated with mSASSS < 1 (p = 0.001) and low bone mineral density (p = 0.01). Increased level of IL-31 might protect against structural damage but is also related to low BMD.

Nemolizumab in patients with moderate-to-severe atopic dermatitis: Randomized, phase II, long-term extension study

BACKGROUND

Nemolizumab, an anti-IL-31 receptor A mAb, improved pruritus, dermatitis, and sleep in adults with moderate-to-severe atopic dermatitis that was inadequately controlled by topical treatments in a phase II, 12-week, randomized, double-blind, placebo-controlled study (part A; NCT01986933).

OBJECTIVE

We sought to assess the long-term efficacy and safety of nemolizumab injected subcutaneously every 4 weeks (Q4W) or every 8 weeks (Q8W) in a 52-week, double-blind extension (part B).

METHODS

During part B, patients continued the previous nemolizumab dose (0.1, 0.5, or 2.0 mg/kg Q4W or 2.0 mg/kg Q8W). Part B end points included percentage improvement from baseline in pruritus visual analog scale and dermatitis scores (including the Eczema Area and Severity Index).

RESULTS

Overall, 216 of 264 patients completed part A, and 191 entered part B; 131 completed part B. In 153 patients randomized to nemolizumab in part A, improvement from baseline in pruritus visual analog scale score was maintained/increased from weeks 12 to 64, with greatest improvement in the 0.5-mg/kg Q4W group (percentage change from baseline at week 64: -73.0, -89.6, -74.7, and -79.1 in the 0.1-, 0.5-, and 2.0-mg/kg Q4W and 2.0-mg/kg Q8W groups, respectively). Improvement from baseline in dermatitis scores was also maintained/increased to week 64 (percentage change in Eczema Area and Severity Index score: -68.5, -75.8, -78.9, and -69.3 in the 0.1-, 0.5-, and 2.0-mg/kg Q4W and 2.0-mg/kg Q8W groups, respectively). Over 64 weeks, 83% to 89% had 1 or more adverse events, with no new safety concerns identified.

CONCLUSION

Nemolizumab for up to 64 weeks was efficacious and overall well tolerated in patients with moderate-to-severe atopic dermatitis inadequately controlled by topical therapy.

IL-33/IL-31 Axis: A Potential Inflammatory Pathway

Cytokines play an important role in the regulation of the immune system (adaptive and innate). Given their importance in proinflammatory processes, cytokines have been used for understanding the pathogenesis and as biomarkers in many diseases. IL-31 and IL-33 are still considered novel cytokines. IL-31 controls signalling and regulates a huge amount of biological functions: it induces proinflammatory cytokines, regulates cell proliferation, and is involved also in tissue remodelling. On the other hand, IL-33 has been identified as an “alarmin” released from the epithelial cells and from different human tissues and organs after a damage following, that is, an inflammatory process. The aim of this literature review is to strengthen the hypothesis about an IL-31/IL-33 axis by evaluating the most recent studies linking these two cytokines. Literature data showed that, in many cases, IL-31 and IL-33 are linked to each other and that their expression is correlated with disease severity. The presence of one interleukin might stimulate the induction of the other, amplifying inflammation and the consequent detrimental processes. In a near future, influencing their balance could be helpful in modulating the first responses of the immune system in order to prevent the development of many inflammation-related diseases.

IL-31: A new key player in dermatology and beyond

IL-31 is a novel cytokine expressed in many human tissues and involved mainly in T_H2-weighted inflammation. IL-31 signals through a receptor complex consisting of IL-31 receptor α and oncostatin M receptor β. The available data show that IL-31 is strongly linked with chronic pruritic skin disorders, such as atopic eczema, and represents a novel target for directed drug therapy. Regulation of immune responses and cellular differentiation and proliferation are recently elucidated effects of IL-31, suggesting a more complex and diverse area of effect for this novel cytokine. This review summarizes the current knowledge on IL-31 and its receptors and the involvement of IL-31 in diseases both in human subjects and mouse models.

New perspectives on the regulation of type II inflammation in asthma

Asthma is a chronic inflammatory disease of the lungs which has been thought to arise as a result of inappropriately directed T helper type-2 (Th2) immune responses of the lungs to otherwise innocuous inhaled antigens. Current asthma therapeutics are directed towards the amelioration of downstream consequences of type-2 immune responses (i.e. β-agonists) or broad-spectrum immunosuppression (i.e. corticosteroids). However, few approaches to date have been focused on the primary prevention of immune deviation. Advances in molecular phenotyping reveal heterogeneity within the asthmatic population with multiple endotypes whose varying expression depends on the interplay between numerous environmental factors and the inheritance of a broad range of susceptibility genes. The most common endotype is one described as "type-2-high" (i.e. high levels of interleukin [IL]-13, eosinophilia, and periostin). The identification of multiple endotypes has provided a potential explanation for the observations that therapies directed at typical Th2 cytokines (IL-4, IL-5, and IL-13) and their receptors have often fallen short when they were tested in a diverse group of asthmatic patients without first stratifying based on disease endotype or severity. However, despite the incorporation of endotype-dependent stratification schemes into clinical trial designs, variation in drug responses are still apparent, suggesting that additional genetic/environmental factors may be contributing to the diversity in drug efficacy. Herein, we will review recent advances in our understanding of the complex pathways involved in the initiation and regulation of type-2-mediated immune responses and their modulation by host factors (genetics, metabolic status, and the microbiome). Particular consideration will be given to how this knowledge could pave the way for further refinement of disease endotypes and/or the development of novel therapeutic strategies for the treatment of asthma .

Regulation of Th2 responses by different cell types expressing the interleukin-31 receptor

BACKGROUND

Interleukin-31 (IL-31) is a recently identified cytokine produced by Th2 cells that is involved in the development of atopic dermatitis-induced skin inflammation and pruritus. Its receptor, IL-31RA, is expressed by a number of cell types, including epithelial cells, eosinophils, and activated monocytes and macrophages. To date, however, the regulation of Th2 responses by distinct cell types and tissues expressing IL-31RA has not been well studied.

METHODS

In this study, Cry j 2, one of the major allergens of Japanese cedar pollen, was administered to IL-31RA-deficient or wild-type (WT) mice via nasal or intraperitoneal injection for induction of specific Th2 responses.

RESULTS

After nasal administration of Cry j 2, IL-31RA-deficient mice showed lower Cry j 2-specific CD4+ T cell proliferation, Th2 cytokine (IL-5 and IL-13) production, and Th2-mediated (IgE, IgG1, and IgG2b) antibody responses than WT mice. In contrast, IL-31RA-deficient mice administered Cry j 2 intraperitoneally showed stronger Th2 immune responses than WT mice.

CONCLUSIONS

These results indicate that IL-31R signaling positively regulates Th2 responses induced by nasal administration of Cry j 2, but negatively regulates these responses when Cry j 2 is administered intraperitoneally. Collectively, these data indicate that the induction of antigen-specific Th2 immune responses might depend on tissue-specific cell types expressing IL-31RA.

The IL-31/IL-31 receptor axis: general features and role in tumor microenvironment

IL-31 is a recently identified cytokine with a well-defined role in the pathogenesis of pruritus. IL-31, whose production is induced by IL-4 and IL-33, binds a heterodimeric receptor (R) composed of the exclusive IL-31RA chain and the shared oncostatin M R. Signaling through the IL-31R involves the MAPK, PI3K/AKT and Jak/STAT pathways. Different variants and isoforms of IL-31RA with different signaling activities have been identified. IL-31 is produced predominantly by circulating Th2 lymphocytes and skin-homing CLA⁺CD45RO⁺ T cells. Studies in humans have demonstrated a pathogenic role for IL-31 in atopic dermatitis and allergic asthma. The first demonstration of the involvement of the IL-31/IL-31R axis in cancer came from studies in patients with mycosis fungoides/Sézary syndrome, the most frequent, cutaneous T cell lymphoma. Tumor cells were shown to produce IL-31, whose serum levels correlated with pruritus intensity. Follicular lymphoma (FL) B cells and their counterparts-germinal center B cells-produced IL-31 and expressed IL-31R, which signaled in the former, but not the latter, cells. IL-31 released in association with microvesicles promoted tumor growth through autocrine/paracrine loops. Malignant mast cells from patients with mastocytosis or Philadelphia-negative myeloproliferative disorder produced IL-31, which contributed to pruritus pathogenesis. Finally, patients with endometrial carcinoma displayed high serum levels of IL-31 and IL-33, which may represent promising disease biomarkers. Targeting strategies for the IL-31/IL-31R axis have been developed, including the CIMM331 humanized anti-human IL-31RA antibody recently tested in a phase I/Ib study.

Interleukin-31 expression and relation to disease severity in human asthma

Interleukin 31 (IL-31) is a novel T helper type 2 effector cytokine that plays an important role in the pathogenesis of allergic diseases. However, its role in human asthma remains unclear. The aim of this study was to measure IL-31 levels in the serum, bronchoalveolar lavage fluid (BALF) and bronchial tissue of asthmatics and healthy subjects, and identify its possible correlation to disease severity. We quantified IL-31 levels in the serum of patients with asthma (n = 44), as well as in controls (n = 22). Of these subjects, 9 asthmatics and five controls underwent bronchoscopy with endobronchial biopsy and BALF collection. Our data showed that serum and BALF IL-31 levels were significantly elevated in patients with asthma compared with controls. Expressions of IL-31 and IL-31 receptor (IL-31RA and OSMR) were more prominent in the bronchial tissue in severe compared to mild asthma and controls. Serum IL-31 levels correlated positively with Th2 related cytokines (IL-5, IL-13, and TSLP), asthma severity or total serum immunoglobulin E (IgE), and inversely with asthma control and the forced expiratory volume in 1 second (FEV₁). The current data may provide insight into the underlying pathogenesis of asthma, in which IL-31 has an important pathogenic role.

Potential diagnostic value of serum/pleural fluid IL-31 levels for tuberculous pleural effusion

The aim of this study was to explore the diagnostic value of IL-31 levels in the pleural fluid and plasma to differentially diagnose tuberculous and malignant pleural effusion. We enrolled 91 cases, including tuberculous pleural effusion (TPE, n = 50), malignant pleural effusion (MPE, n = 41), other cases including pneumonia with pleural fluid, pulmonary tuberculosis and healthy people as controls. Whole blood was stimulated with the M. tuberculosis-specific antigens and plasma was collected. The multiplex bead-based cytokine immunoassay was employed to measure the levels of various cytokines. IL-31 was found to be the most prominent cytokine (P < 0.0001), and with an optimal cut-off value of 67.5 pg/mL, the sensitivity and specificity for the diagnosis of TPE were 86% and 100%, respectively. Furthermore, the tuberculosis-specific IL-31 levels in the plasma of TPE patients were higher than that of MPE patients (P = 0.0002). At an optimal cut-off value of 23.9 pg/mL, the sensitivity and specificity for the diagnosis of TPE were 92.9% and 85.7%, respectively. Ultimately, the combination of pleural fluid with the plasma tuberculosis-specific IL-31 levels improved the sensitivity and specificity to 94.0% and 95.1%, respectively. Thus, we identified a novel biomarker for the diagnosis of TPE for clinical application.

Unique IL-13Rα2-based HIV-1 vaccine strategy to enhance mucosal immunity, CD8(+) T-cell avidity and protective immunity

We have established that mucosal immunization can generate high-avidity human immunodeficiency virus (HIV)-specific CD8(+) T cells compared with systemic immunization, and interleukin (IL)-13 is detrimental to the functional avidity of these T cells. We have now constructed two unique recombinant HIV-1 vaccines that co-express soluble or membrane-bound forms of the IL-13 receptor α2 (IL-13Rα2), which can "transiently" block IL-13 activity at the vaccination site causing wild-type animals to behave similar to an IL-13 KO animal. Following intranasal/intramuscular prime-boost immunization, these IL-13Rα2-adjuvanted vaccines have shown to induce (i) enhanced HIV-specific CD8(+) T cells with higher functional avidity, with broader cytokine/chemokine profiles and greater protective immunity using a surrogate mucosal HIV-1 challenge, and also (ii) excellent multifunctional mucosal CD8(+) T-cell responses, in the lung, genito-rectal nodes (GN), and Peyer's patch (PP). Data revealed that intranasal delivery of these IL-13Rα2-adjuvanted HIV vaccines recruited large numbers of unique antigen-presenting cell subsets to the lung mucosae, ultimately promoting the induction of high-avidity CD8(+) T cells. We believe our novel IL-13R cytokine trap vaccine strategy offers great promise for not only HIV-1, but also as a platform technology against range of chronic infections that require strong sustained high-avidity mucosal/systemic immunity for protection.

New concepts in diagnostics for infectious diarrhea

Conventional approaches to the diagnosis of infectious diarrhea must include several modalities to detect an array of potential viruses, bacteria, and parasites. We will provide a general overview of the wide range of diagnostic modalities available for enteropathogens, briefly discuss some of the limitations of conventional methods, and then focus on new molecular methods, including real-time PCR and next-generation sequencing. In particular, we will discuss quantitation of pathogen load with these techniques. We will then describe examples whereby novel diagnostics may help illuminate the etiology of infectious diarrhea, where they may not, and how they may benefit studies of immunity to enteric infections.

Phenotypic and functional characterization of mesenchymal stem cells from chorionic villi of human term placenta

BACKGROUND

Bone marrow derived mesenchymal stem cells (BM-MSCs) are used extensively in transplantation but their use is associated with many problems including low abundance in BM, low overall number, decreased differentiation potential with age and the invasive isolation procedures needed to obtain BM. We report a novel method of isolating placental MSCs (pMSCs) from chorionic villi, which exhibit the phenotypic and functional characteristics that will make them an attractive source of MSCs for cell-based therapy.

METHODS

A novel explant approach was used to isolate pMSCs from chorionic villi of human placentae. These pMSCs were characterized by flow cytometry and were differentiated into adipocytes, osteocytes and chondrocytes using differentiation medium as demonstrated by cytochemical staining. The gene and protein expression profiles of pMSCs were also characterized using real time polymerase chain reaction (PCR) and flow cytometry, respectively. In addition, cytokine secretion by pMSCs was also analysed using sandwich enzyme-linked immunosorbent assay (ELISA) technique. Moreover, the migration and proliferation potentials of pMSCs were also determined.

RESULTS

pMSCs were isolated from fetal part of the chorionic villi and these pMSCs expressed CD44, CD90, CD105, CD146, CD166 and HLA-ABC but not CD14, CD19, CD40, CD45, CD80, CD83, CD86 and HLA-DR. In addition, these pMSCs differentiated into osteocytes, chondrocytes and adipocytes and they also expressed several adhesion molecules, chemokines/receptors, growth factor receptors and cytokines/receptors. Moreover, they secreted many cytokines (IL-1Ra, IL6, IL8, IL10, IL11 and IL15) and they were able to proliferate. Furthermore, they migrated in response to chemotactic factors including stromal cell-derived factor-1 (SDF-1), platelet derived growth factor (PDGF), hepatocyte growth factor (HGF), and monocyte chemotactic protein-1 (MCP-1).

CONCLUSIONS

We devised a novel explant method of isolating pMSCs that expressed many biological factors responsible for mediating cellular processes such as migration/homing, immune modulation and angiogenesis. Therefore, we suggest that pMSCs prepared from human term placental chorionic villous explants are an attractive source of MSCs for cell therapy.

The release of IL-31 and IL-13 after nasal allergen challenge and their relation to nasal symptoms

Background

IL-31, a recently discovered member of the gp130/IL-6 cytokine family, is mainly expressed by human mast cells and T helper type 2 cells. IL-31 is a key trigger of atopic dermatitis. Recent studies also suggest a role of IL-31 in the pathogenesis of other allergic diseases including allergic rhinitis. In the present study we studied the release of IL-31 and IL-13 in allergen-challenged allergic rhinitis patients.

Methods

Seven seasonal allergic volunteers underwent unilateral nasal provocation with allergen (and a control challenge) with the disc method out of the allergy season. Nasal symptom scores (rhinorrhea, itching, sneezing, obstruction) and bilateral nasal secretions were quantified before and after allergen provocation. IL-13 and IL-31 in nasal secretions and serum were measured by electrochemiluminescent immunoassay or ELISA, respectively.

Results

Nasal allergen challenge induced the typical clinical symptoms and physiological changes. IL-31 and IL-13 in nasal secretions increased in four and five, respectively, volunteers at 5 h after allergen but not after control challenge. We observed correlation trends between nasal IL-31 concentrations and IL-13 concentrations (r = 0.9, p = 0.002), and IL-31 contents and symptom scores (r = 0.9, p = 0.013) 5 h after allergen provocation. No IL-31 could be detected contralaterally or systemically in the sera.

Conclusions

The observed local upregulation of IL-31 mainly during the late phase reaction after nasal allergen challenge suggests a role of IL-31 in allergic rhinitis. In which way IL-31 modulates the inflammatory reaction and type 2 responses in allergic rhinitis remains to be investigated.

Dendritic cells activated by IFN-γ/STAT1 express IL-31 receptor and release proinflammatory mediators upon IL-31 treatment

IL-31 is a T cell-derived cytokine that signals via a heterodimeric receptor composed of IL-31Rα and oncostatin M receptor β. Although several studies have aimed to investigate IL-31-mediated effects, the biological functions of this cytokine are currently not well understood. IL-31 expression correlates with the expression of IL-4 and IL-13 and is associated with atopic dermatitis in humans, indicating that IL-31 is involved in Th2-mediated skin inflammation. Because dendritic cells are the main activators of Th cell responses, we posed the question of whether dendritic cells express the IL-31R complex and govern immune responses triggered by IL-31. In the current study, we report that primary human CD1c(+) as well as monocyte-derived dendritic cells significantly upregulate the IL-31Rα receptor chain upon stimulation with IFN-γ. EMSAs, chromatin immunoprecipitation assays, and small interfering RNA-based silencing assays revealed that STAT1 is the main transcription factor involved in IFN-γ-dependent IL-31Rα expression. Subsequent IL-31 stimulation resulted in a dose-dependent release of proinflammatory mediators, including TNF-α, IL-6, CXCL8, CCL2, CCL5, and CCL22. Because these cytokines are crucially involved in skin inflammation, we hypothesize that IL-31-specific activation of dendritic cells may be part of a positive feedback loop driving the progression of inflammatory skin diseases.

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

Chronic systemic infection exacerbates ischemic brain damage via a CCL5 (regulated on activation, normal T-cell expressed and secreted)-mediated proinflammatory response in mice

Infection and systemic inflammation are risk factors for cerebrovascular diseases and poststroke infections impair outcome in stroke patients, although the mechanisms of their contribution are mostly unknown. No preclinical studies have identified how chronic infection affects ischemic brain damage and which key inflammatory mediators are involved. We used a well established model of gut infection (Trichuris muris) to study how chronic infection contributes to brain injury. We show that, in mice, infection that leads to a chronic Th1-polarized immune response dramatically (60%) exacerbates brain damage caused by experimental stroke. Chronic Th1-type infection resulted in systemic upregulation of proinflammatory mediators and profoundly altered stroke-induced early (40 min to 4 h) and late (48 h) inflammation in the brain and peripheral tissues. Using the same infection, we show that a Th1-, but not Th2-polarized response augments brain injury by increasing the Th1 chemokine CCL5 [regulated on activation, normal T-cell expressed and secreted (RANTES)] systemically. This infection-associated response paralleled altered regulatory T-cell response, accelerated platelet aggregation in brain capillaries, and increased microvascular injury and matrix metalloproteinase activation after stroke. Antibody neutralization of RANTES reversed the effect of chronic infection on brain damage, microvascular MMP-9 activation, and cellular inflammatory response. Our results suggest that chronic infection exacerbates ischemic brain damage via a RANTES-mediated systemic inflammatory response, which leads to delayed resolution of inflammation and augmented microvascular injury in the brain.

Improved survival of mice deficient in secretory immunoglobulin M following systemic infection with Cryptococcus neoformans

Cryptococcus neoformans causes severe, and often fatal, disease (cryptococcosis) in immunocompromised patients, particularly in those with HIV/AIDS. Although resistance to cryptococcosis requires intact T-cell immunity, a possible role for antibody/B cells in protection against natural disease has not been definitively established. Previous studies of the antibody response to the C. neoformans capsular polysaccharide glucuronoxylomannan (GXM) have demonstrated that patients who are at increased risk for cryptococcosis have lower serum levels of GXM-reactive IgM than those who are not at risk, leading to the hypothesis that IgM might contribute to resistance to cryptococcosis. To determine the influence of IgM on susceptibility to systemic cryptococcosis in a murine model, we compared the survival of mice deficient in serum IgM (secretory IgM deficient [sIgM(-/-)]) and C57BL/6 x 129Sv (control) mice after intraperitoneal infection with C. neoformans strain 24067 and analyzed the splenic B- and T-cell subsets by flow cytometry and the serum and splenic cytokine/chemokine and serum antibody profiles of each mouse strain. The results showed that sIgM(-/-) mice survived significantly longer than control mice when challenged with 10(5) CFU of C. neoformans 24067. Naïve sIgM(-/-) mice had higher levels of B-1 (CD5(+)) B cells, proinflammatory mediators (interleukin-6 [IL-6], IL-1beta, MIP-1beta, tumor necrosis factor alpha [TNF-alpha], and gamma interferon [IFN-gamma]), and anti-inflammatory mediators (IL-10 and IL-13) and significantly higher titers of GXM-specific IgG2a 3 weeks postinfection. In addition, CD5(+) splenocytes from both mouse strains had fungicidal activity against C. neoformans. Taken together, these results suggest that the inflammatory milieu in sIgM(-/-) mice might confer enhanced resistance to systemic cryptococcosis, stemming in part from the antifungal activity of B-1 B cells.