Roles of basophils and mast cells in cutaneous inflammation

ERK/STAT3 activation through CCL17/CCR4 axis-mediated type 2 cytokine-involved signaling pathways in Th2 cells regulates cutaneous drug reactions

Cutaneous drug reactions (CDRs) are common drug-induced allergic reactions that cause severe consequences in HIV/AIDS patients. The CCL17/CCR4 axis is involved in the immune mechanism of allergic diseases, but its role in the CDRs has not been determined. Here, we aimed to determine the role of the CCL17/CCR4 axis and the underlying mechanism involved in CDRs. In this study, the serum cytokine levels in patients with CDR and healthy controls were measured. The CCL17-triggered allergic profile was screened via a PCR array. Apoptosis of keratinocytes cocultured with CCL17-stimulated Th2 cells was analyzed by flow cytometry. An NVP-induced rat CDR model was established, and dynamic inflammatory factor levels and Th2 cells in the peripheral blood of the rats were measured. Rat skin lesions and signaling pathways in Th2 cells were also analyzed. We showed that the serum CCL17 level was significantly upregulated in CDR patients (P = 0.0077), and the Th2 cell subgroup was also significantly elevated in the CDR rats. The CCL17/CCR4 axis induces Th2 cells to release IL-4 and IL-13 via the ERK/STAT3 pathway. The CCR4 antagonist compound 47 can alleviate rash symptoms resulting from NVP-induced drug eruption, Th2 cell subgroup, IL-4, and IL-13 and inhibit keratinocyte apoptosis. Taken together, these findings indicate that the CCL17/CCR4 axis mediates CDR via the ERK/STAT3 pathway in Th2 cells and type 2 cytokine-induced keratinocyte apoptosis.

Mast Cell Deficiency in Mice Attenuates Insulin Phenolic Preservative-Induced Inflammation

One major obstacle that limits the lifespan of insulin infusion pumps is surmounting the tissue site reaction at the device implantation site. All commercial insulin formulations contain insulin phenolic preservatives (IPPs) designed to ensure insulin protein stability and prolong shelf-life. However, our laboratory demonstrated that these preservatives are cytotoxic and induce inflammation. Mature mast cells (MCs) reside in cutaneous tissue and are one of the first responders to an epidermal breach. Upon activation, MCs release proinflammatory and immunomodulatory prepacked mediators that exacerbate these inflammatory reactions. Thus, we hypothesized that once the epidermis is breached, cutaneous MCs are triggered inciting the inflammatory response to IPP-induced inflammation. This hypothesis was pursued utilizing our modified in vivo mouse air pouch model, including a c-kit dependent (C57BL/6J-kitW-sh/W-sh) and a c-kit independent (Cpa3-Cre; Mcl-1fl/fl) MC-deficient mouse model. Leukocytes were quantified in the mouse air pouch lavage fluid following flow cytometry analysis for IPP infusion under three different states, insulin-containing phenolic preservatives (Humalog®), insulin preservatives alone, and normal saline as a control. The air pouch wall was assessed using histopathological evaluations. Flow cytometry analysis demonstrated a statistically significant difference in inflammatory cell recruitment for both MC-deficient mouse models when compared to the control strain including infused control saline. Significantly less inflammation was observed at the site of infusion for the MC-deficient strains compared to the control strain. Overall, concordant results were obtained in both mouse types, C57Bl6-kitW-sh/W-sh and Cpa3-Cre; Mcl-1fl/fl. These findings in multiple model systems support the conclusion that MCs have important or possible unique roles in IPP-induced inflammation.

Blood Basophils Relevance in Chronic Rhinosinusitis with Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is characterized by eosinophilic asthma, chronic rhinosinusitis with nasal polyps (CRSwNP) and intolerance to cyclooxygenase-1 inhibitors. Interest is emerging in studying the role of circulating inflammatory cells in CRSwNP pathogenesis and its course, as well as their potential use for a patient-tailored approach. By releasing IL-4, basophils play a crucial role in activating the Th2-mediated response. The main aim of this study was to, first, investigate the level of the pre-operative blood basophils' values, blood basophil/lymphocyte ratio (bBLR) and blood eosinophil-to-basophil ratio (bEBR) as predictors of recurrent polyps after endoscopic sinus surgery (ESS) in AERD patients. The secondary aim was to compare the blood basophil-related variables of the AERD series (study group) with those of a control group of 95 consecutive cases of histologically non-eosinophilic CRSwNP. The AERD group showed a higher recurrence rate than the control group (p < 0.0001). The pre-operative blood basophil count and pre-operative bEBR were higher in AERD patients than in the control group (p = 0.0364 and p = 0.0006, respectively). The results of this study support the hypothesis that polyps removal may contribute to reducing the inflammation and activation of basophils.

The Role of Type 2 Innate Lymphoid Cells in Allergic Diseases

Allergic diseases are significant diseases that affect many patients worldwide. In the past few decades, the incidence of allergic diseases has increased significantly due to environmental changes and social development, which has posed a substantial public health burden and even led to premature death. The understanding of the mechanism underlying allergic diseases has been substantially advanced, and the occurrence of allergic diseases and changes in the immune system state are known to be correlated. With the identification and in-depth understanding of innate lymphoid cells, researchers have gradually revealed that type 2 innate lymphoid cells (ILC2s) play important roles in many allergic diseases. However, our current studies of ILC2s are limited, and their status in allergic diseases remains unclear. This article provides an overview of the common phenotypes and activation pathways of ILC2s in different allergic diseases as well as potential research directions to improve the understanding of their roles in different allergic diseases and ultimately find new treatments for these diseases.

Induced Transient Immune Tolerance in Ticks and Vertebrate Host: A Keystone of Tick-Borne Diseases?

Ticks and tick transmitted infectious agents are increasing global public health threats due to increasing abundance, expanding geographic ranges of vectors and pathogens, and emerging tick-borne infectious agents. Greater understanding of tick, host, and pathogen interactions will contribute to development of novel tick control and disease prevention strategies. Tick-borne pathogens adapt in multiple ways to very different tick and vertebrate host environments and defenses. Ticks effectively pharmacomodulate by its saliva host innate and adaptive immune defenses. In this review, we examine the idea that successful synergy between tick and tick-borne pathogen results in host immune tolerance that facilitates successful tick infection and feeding, creates a favorable site for pathogen introduction, modulates cutaneous and systemic immune defenses to establish infection, and contributes to successful long-term infection. Tick, host, and pathogen elements examined here include interaction of tick innate immunity and microbiome with tick-borne pathogens; tick modulation of host cutaneous defenses prior to pathogen transmission; how tick and pathogen target vertebrate host defenses that lead to different modes of interaction and host infection status (reservoir, incompetent, resistant, clinically ill); tick saliva bioactive molecules as important factors in determining those pathogens for which the tick is a competent vector; and, the need for translational studies to advance this field of study. Gaps in our understanding of these relationships are identified, that if successfully addressed, can advance the development of strategies to successfully disrupt both tick feeding and pathogen transmission.

Dietary osteopontin-enriched algal protein as nutritional support in weaned pigs infected with F18-fimbriated enterotoxigenic Escherichia coli

This study investigated the effects of dietary osteopontin (OPN)-enriched algal protein on growth, immune status, and fecal fermentation profiles of weaned pigs challenged with a live infection of F18-fimbriated enterotoxigenic E. coli (ETEC). At 21 d of age, 54 pigs (5.95 ± 0.28 kg BW; blocked by BW) were allotted to 1 of 3 experimental groups combining dietary and health statuses. A control diet, containing 1% wild-type algal protein, was fed to both sham-inoculated (NC) and ETEC-inoculated (PC) pigs, while the test diet contained 1% OPN-enriched algal protein as fed only to ETEC-inoculated pigs (OA). All pigs received their assigned dietary treatment starting at study initiation to permit a 10-d acclimation period prior to inoculation. Growth performance, fecal dry matter, as well as hematological, histopathological, immune, and microbiota outcomes were analyzed by ANOVA, where treatment and time were considered as fixed effects and pig as a random effect; significance was accepted at P < 0.05. Overall, ETEC-inoculated pigs (PC and OA) exhibited decreased (P < 0.05) ADG and G:F, as well as increased (P < 0.05) peripheral blood helper T-cells and total leukocyte counts, compared with NC pigs during the postinoculation period. The OA treatment also elicited the highest (P < 0.05) concentrations of circulating tumor necrosis factor-α and volatile fatty acid concentrations in luminal contents at various postinoculation time-points, compared with other treatments. A principal coordinate analysis based on Unifrac weighted distances indicated that NC and OA groups had similar overall bacterial community structures, while PC pigs exhibited greater diversity, but infection status had no impact on α-diversity. Osteopontin-specific effects on microbial community structure included enrichment within Streptococcus and Blautia genera and decreased abundance of 12 other genera as compared with PC pigs. Overall, ETEC-infected pigs receiving 1% OPN-enriched algal protein exhibited changes immunity, inflammatory status, and colonic microbial community structure that may benefit weanling pigs experiencing F18 ETEC infection.

Blood Eosinophilic and Basophilic Trends in Recurring and Non-Recurring Eosinophilic Rhinosinusitis With Nasal Polyps

BACKGROUND

Very few studies have compared blood eosinophil and basophil levels before and after surgery in patients with eosinophilic CRSwNP (eCRSwNP). No investigations seem to have repeatedly measured them pre- and postoperatively in eCRSwNP patients with recurring versus non-recurring disease to examine how their levels evolved.

OBJECTIVE

Hence this study to analyze blood eosinophil and basophil levels in patients with eCRSwNP immediately before surgery and afterwards, at 4 months, 1 year, and then yearly up to 5 years.

METHODS

Fifty-one eCRSwNP patients were enrolled, who all had preoperative laboratory data and the results of at least 4 of the 6 scheduled postoperative follow-up tests.

RESULTS

Seventeen patients had recurrent disease. Blood eosinophil counts (p = 0.005) and percentages (p = 0.002) were both higher in these patients than in those whose eCRSwNPs did not recur after surgery. Blood basophil counts (p = 0.04) and percentages (p < 0.05) were also significantly higher in patients whose eCRSwNPs relapsed. The time by relapse interaction was not significant for either counts or percentages, though an effect of time was detected for basophil counts (p = 0.01).

CONCLUSIONS

In eCRSwNP, the statistical analysis of repeated quantitative laboratory data can shed light on the evolution of a patient's systemic inflammatory picture in response to previous treatments, and above all to long-term therapies. Long-term monitoring of blood eosinophil and basophil levels could be of significant value when monoclonal antibodies that inhibit IL signaling will widely enter in clinical practice for eCRSwNP treatment to follow the effectiveness of therapy over time.

Limited role of mast cells during infection with the parasitic nematode Litomosoides sigmodontis

Mast cells are innate effector cells that due to their localization in the tissue form the first line of defense against parasites. We have previously shown that specifically mucosal mast cells were essential for the termination of the intestinal Strongyloides ratti infection. Here, we analyze the impact of mast cells on the immune response and defense against the tissue-dwelling filarial nematode Litomosoides sigmodontis using mast cell-deficient Cpa3^cre mice. Despite an increase and an activation of mast cells at the site of infection in wildtype BALB/c mice the outcome of L. sigmodontis infection was not changed in mast cell-deficient BALB/c Cpa3^cre mice. In Cpa3^cre mice neither vascular permeability induced by blood-sucking mites nor the migration of L3 was altered compared to Cpa3 wildtype littermates. Worm burden in the thoracic cavity was alike in the presence and absence of mast cells during the entire course of infection. Although microfilaremiae in the peripheral blood increased in mast cell-deficient mice at some time points, the infection was cleared with comparable kinetics in the presence and absence of mast cells. Moreover, mast cell deficiency had no impact on the cytokine and antibody response to L. sigmodontis. In summary, our findings suggest that mast cells are not mandatory for the initiation of an appropriate immune response and host defense during L. sigmodontis infection in mice.

Mast cells are innate cells that are equipped with biologically potent granule proteins. Due to their localization in many tissues they form the first line of defense against parasites such as helminths. In the current study we analyzed the impact of mast cell deficiency on the course of a tissue-dwelling helminth infection. Mice were infected with the filarial nematode L. sigmodontis in the presence and absence of mast cells. We show that mast cell numbers increase at the site of infection and that mast cells are activated. Despite the recruitment of mast cells in infected wildtype BALB/c mice, worm burden in the thoracic cavity and final eradication of microfilariae from the peripheral blood were alike in mast cell-deficient and wildtype mice. Mast cell deficiency had no impact on the anti-helminth immune response. In summary, our findings suggest that mast cells are not required for a protective immune response against L. sigmodontis infection in mice.

Novel reactivation and degranulation of mast cells

Mast cells (MCs) degranulation is a key process during the allergic inflammatory response. MCs release their preformed and new synthesized granules after activation. We found that granules were released partially and selectively after the activation of bone marrow-derived mouse mast cells (BMMCs). Next, we investigated the response of degranulated MCs to a new challenge. BMMCs were activated by antibody/antigen (IgE/Ag) or compound 48/80 (C48/80). The degranulated BMMCs were then reactivated by either IgE/Ag or C48/80 without time intervals. Flow cytometry was used to detect the expression of CD117, FcεRI, and intracellular granules of BMMCs, and BMMCs degranulation was detected using the β-hexosaminidase release assay. The morphology of BMMCs was observed by staining with toluidine blue. Degranulated BMMCs activated by IgE/Ag failed to respond to the same IgE/Ag challenge and released β-hexosaminidase independent of unoccupied FcεRI, but responded to C48/80. Degranulated BMMCs activated by C48/80 responded to either IgE/Ag or C48/80. These results indicated that degranulated BMMCs could be reactivated and released granule mediators again, this revealed the unique mediator releasing mechanism of degranulated MCs and their potential function in maintaining inflammation or causing hypersensitivity.

IL-37 is protective in allergic contact dermatitis through mast cell inhibition

Allergic contact dermatitis (ACD), characterized predominantly by erythema, vesiculation, and pruritus, is a T cell-mediated skin inflammatory condition. Among immune cells involved in ACD, mast cells (MCs) play an essential role in its pathogenesis. As an inhibitor of proinflammatory IL-1 family members, interleukin 37 (IL-37) has been shown to ameliorate inflammatory responses in various allergic diseases. In this study, we assessed the immunomodulatory effect of IL-37 on allergic inflammation using a 2,4-dinitrofluorobenzene (DNFB)-induced ACD rat model and isolated rat peritoneal mast cells (RPMCs). Systematic application of IL-37 significantly relieved ear swelling, reduced inflammatory cell infiltration, decreased inflammatory cytokine production (TNF-α, IL-1β, IFN-γ, and IL-13), inhibited MC recruitment, lowered IgE levels, and reduced IL-33 production in the local ear tissues with DNFB challenge. Additionally, RPMCs isolated from ACD rats with IL-37 intervention showed downregulation of IL-6, TNF-α, IL-13, and MCP-1 production following IL-33 stimulation, and reduction of β-hexosaminidase and histamine release under DNP-IgE/HSA treatment. Moreover, IL-37 treatment also significantly restrained NF-κB activation and P38 phosphorylation in ACD RPMCs. SIS3, a specific Smad3 inhibitor, abolished the suppressive effects of IL-37 on MC-mediated allergic inflammation, suggesting the participation of Smad3 in the anti-ACD effect of IL-37. These findings indicated that IL-37 protects against IL-33-regulated MC inflammatory responses via inhibition of NF-κB and P38 MAPK activation accompanying the regulation of Smad3 in rats with ACD.

No Differences in Nasal Tissue Inflammatory Cells and Adhesion Molecules (iCAM-1 and vCAM-1) Based on the Comparison of EGPA With Eosinophilic Chronic Sinusitis With Polyposis

Background

An example of aggressive eosinophilic polyposis can be found in eosinophilic granulomatosis with polyangiitis (EGPA). Intercellular adhesion molecule-1 (iCAM-1) and vascular cell adhesion molecule-1 (vCAM-1) play a part in mediating the recruitment and adhesion of leukocytes to the vessel wall, and their blood-to-tissue migration under inflammatory conditions.

Objective

This prospective study compared 3 groups—patients with a definite diagnosis EGPA, non-EGPA patients with phenotypic features suggestive of EGPA, and patients with non-eosinophilic nasal polyposis (controls)—in terms of nasal tissue histology, iCAM-1 and vCAM-1 expression, and blood inflammatory cells.

Methods

A total of 58 adults underwent sinus surgery (13 patients with EGPA, 23 suspected of having EGPA, and 22 controls).

Results

Mean tissue eosinophil counts were significantly higher in EGPA patients and suspected cases of EGPA than in controls. Although iCAM-1 and vCAM-1 were diffusely expressed in sinonasal tissues, they did not differently stain EGPA, eosinophilic-type and non-eosinophilic polyposis. Blood basophil and eosinophil levels were high in both the EGPA and the suspected EGPA groups. Intergroup differences were found for eosinophils but not for basophils.

Conclusions

We do not have yet blood or tissue markers able to differentiate the early phase of EGPA from chronic rhinosinusitis with nasal polyps. Further investigations are mandatory considering EGPA patients at their initial diagnosis and before any treatment, in terms of nasal histology and blood inflammatory cells, to identify markers characterizing sinonasal mucosa inflammation and useful for an early diagnosis of EGPA.

Novel cutaneous mediators of chemical allergy

Chemical allergy can manifest into allergic contact dermatitis and asthma and the importance of skin sensitization in both of these diseases is increasingly being recognized. Given the unique characteristics of chemical allergy, coupled with the distinct immunological microenvironment of the skin research is still unraveling the mechanisms through which sensitization and elicitation occur. This review first describes the features of chemical sensitization and the known steps that must occur to develop a chemical allergy. Next, the unique immunological properties of the skin - which may influence chemical sensitization - are highlighted. Additionally, mediators involved with the development of allergy are reviewed, starting with early ones - including the properties of haptens, skin integrity, the microbiome, the inflammasome, and toll-like receptors (TLR). Novel cellular mediators of chemical sensitization are highlighted, including innate lymphoid cells, mast cells, T-helper (T_H) cell subsets, and skin intrinsic populations including γδ T-cells and resident memory T-cells. Finally, this review discusses two epigenetic mechanisms that can influence chemical sensitization, microRNAs and DNA methylation. Overall, this review highlights recent research investigating novel mediators of chemical allergy that are present in the skin. It also emphasizes the need to further explore these mediators to gain a better understanding of what makes a chemical an allergen, and how best to prevent the development of chemical-induced allergic diseases.

Modulation of the extraneuronal cholinergic system on main innate response leukocytes

The expression of elements of the cholinergic system has been demonstrated in non-neuronal cells, such as immune cells, where acetylcholine modulates innate and adaptive responses. However, the study of the non-neuronal cholinergic system has focused on lymphocyte cholinergic mechanisms, with less attention to its role of innate cells. Considering this background, the aims of this review are 1) to review information regarding the cholinergic components of innate immune system cells; 2) to discuss the effect of cholinergic stimuli on cell functions; 3) and to describe the importance of cholinergic stimuli on host immunocompetence, in order to set the base for the design of intervention strategies in the biomedical field.

BPA Alters Estrogen Receptor Expression in the Heart After Viral Infection Activating Cardiac Mast Cells and T Cells Leading to Perimyocarditis and Fibrosis

Myocarditis is an inflammatory heart disease that leads to dilated cardiomyopathy (DCM) and heart failure. Sex hormones play an important role in the development of myocarditis with testosterone driving disease in males and estrogen being cardioprotective in females. The human population is widely exposed to the endocrine disruptor bisphenol A (BPA) from plastics such as water bottles, plastic food containers, copy paper, and receipts. Several clinical and numerous animal studies have found an association between elevated BPA levels and cardiovascular disease. A recent report found elevated levels of BPA in the serum of patients with DCM compared to healthy controls. In this study we examined whether exposure to BPA for 2 weeks prior to viral infection and leading up to myocarditis at day 10 altered inflammation in female BALB/c mice housed in standard plastic cages/water bottles with soy-free food and bedding. We found that a human relevant dose of BPA (25 μg/L) in drinking water, with an estimated exposure of 5 μg BPA/kg BW, significantly increased myocarditis and pericarditis compared to control water without altering viral genome levels in the heart. BPA exposure activated ERα and ERβ in the spleen 24 h after infection and phosphorylated ERα and ERβ during myocarditis, but decreased ERα and increased ERβ mRNA in the heart as measured by qRT-PCR. Exposure to BPA significantly increased CD4⁺ T cells, IFNγ, IL-17A, TLR4, caspase-1, and IL-1β in the heart. BPA exposure also increased cardiac fibrosis compared to controls. Mast cells, which are associated with cardiac remodeling, were found to increase in number and degranulation, particularly along the pericardium. Interestingly, plastic caging/water bottle exposure alone led to increased mast cell numbers, pericardial degranulation and fibrosis in female BALB/c mice compared to animals housed in glass cages/water bottles with soy-free food and bedding. These data suggest that BPA exposure may increase the risk of developing myocarditis after a viral infection in women.

MicroRNA-126 accelerates IgE-mediated mast cell degranulation associated with the PI3K/Akt signaling pathway by promoting Ca2+ influx

Mast cells (MCs) have been reported to serve a crucial role in allergic diseases, including asthma, allergic rhinitis and anaphylaxis. A previous study revealed that microRNA-126 (miR-126) was associated with airway hyperresponsiveness induced by house dust mites, however the molecular mechanisms were unclear. The present study aimed to investigate the effect of miR-126 on immunoglobulin E (IgE)-regulated MC degranulation and explore its underlying mechanisms. miR-126 expression was quantified using a rat model in vivo and in rat peritoneal mast cells (RPMCs) in vitro. Overexpression or downregulation of miR-126 was established by transfection with miR-126 mimics or miR-126 inhibitors and MC degranulation was subsequently evaluated. The effect of miR-126 on protein kinase B (Akt) and phosphorylated Akt protein expression was examined by western blot analysis. The phosphoinositide 3-kinase (PI3K) inhibitor (LY294002) was used to determine the role of the PI3K/Akt signaling pathway. In addition, cytosolic calcium (Ca²⁺) levels were measured by a fura-2 assay. The results demonstrated that miR-126 expression was upregulated in the ear tissues of rats with allergic contact dermatitis and IgE-activated MCs. The overexpression of miR-126 in RPMCs was established following miR-126 mimic transfection. The release of β-hexosaminidase and histamine, markers of MC degranulation, were significantly increased in cells with miR-126 overexpression. The phosphorylation of Akt was significantly increased following transfection with miR-126 mimics in stimulated cells, however the signaling activation was abrogated by LY294002. In addition, Ca²⁺ influx was significantly promoted in stimulated RPMCs overexpressing miR-126. These results indicate that miR-126 accelerated IgE-mediated MC degranulation associated with the PI3K/Akt signaling pathway by promoting Ca²⁺ influx. This suggests that miR-126 may be a promising therapeutic target for the treatment of allergic skin diseases.

The effects of resiquimod in an ovalbumin-induced allergic rhinitis model

Growing evidence indicates that the Toll-like receptor7/8(TLR7/8) agonist resiquimod (R848) is a potential inhibitor of type-2 immunity. However, the mechanisms mediating its therapeutic effects are not fully understood. This study investigated the effects of R848 on OVA-induced allergic rhinitis(AR) mice and the expression of IL-25, IL-33, TSLP, T-cell immunoglobulin mucin1 (TIM1) and T-cell immunoglobulin mucin3 (TIM3). BALB/c mice were intranasally sensitized and challenged with ovalbumin (OVA), and R848 was intraperitoneally injected into AR mice. Histological changes in the nasal mucosa were evaluated by hematoxylin and eosin (H & E) and Periodic Acid-Schiff (PAS) staining; cytokine levels in serum were measured with enzyme-linked immunosorbent assays (ELISAs);the mRNA expression levels of IFN-γ, IL-17 and Foxp3 in the spleen determined by quantitative real-time RT-PCR (qRT-PCR); the proportions of Th1, Th2, Th17, Treg and TIM3 + IFN-γ + Th1 cells in the spleen were assessed with flow cytometry; TIM1, TIM3 and IL-33 expression levels in the nasal mucosa were evaluated with immunofluorescence staining(IF).R848 alleviated the nasal allergic symptoms; reduced eosinophil cell infiltration, goblet cell hyperplasia in the nasal mucosa; reduced IL-13, IL-17, IL-25 and IL-33 levels in serum; upregulated the relative mRNA expression of IFN-γ and Foxp3, and downregulated the relative mRNA expression of IL-17 in the spleen; decreased Th2, Th17 and TIM3 + IFN-γ + Th1 cells ratios, increased the proportion of Th1 and Treg cells in the spleen; suppressed TIM1 and TIM3,but increased IL-33 expression in the nasal mucosa in OVA-induced AR mice. R848 suppresses IL-25, IL-33 released and TIM1, TIM3 expression, which may contribute to its anti-allergic effects.

Protease-activated receptor-2 suppresses interleukin (IL)-10 expression in B cells via upregulating Bcl2L12 in patients with allergic rhinitis

BACKGROUND AND AIMS

The function of interleukin (IL)-10-producing B cells (B10 cell) is compromised in patients with allergic diseases. Protease-activated receptor (PAR)-2 has immunoregulatory functions. This study aimed to elucidate the role of PAR2 in the suppression of IL-10 expression in peripheral B cells.

METHODS

Peripheral blood B cells were collected from patients with allergic rhinitis (AR). A correlation between the expression of Bcl2-like protein 12 (Bcl2L12) and IL-10 in the B cells was analyzed. An AR mouse model was developed.

RESULTS

We observed that the expression of IL-10 was lower in the peripheral B cells from patients with airway allergy. A negative correlation was identified between the expression of IL-10 and PAR2 in B cells. Activation of PAR2 of B cells increased the expression of Bcl2L12 and suppression of LPS-induced IL-10 expression, which were inhibited by knocking down the Bcl2L12 gene. Treating B cells from AR patients with Bcl2L12-shRNA-carrying liposomes reversed the capability of IL-10 expression and the immunosuppressive function. Administration of Bcl2L12 shRNA-carrying liposomes attenuated experimental AR in mice.

CONCLUSIONS

Activation of PAR2 inhibits the expression of IL-10 in B cells, which can be reversed by treating B cells with Bcl2L12 shRNA-carrying liposomes. The data suggest that regulation of Bcl2L12 may be a novel approach in the treatment for AR.

Innate lymphoid cells in allergic and nonallergic inflammation

In the last decade, the full picture of the role of innate lymphoid cells (ILCs) has been gradually revealed. ILCs are classified into 3 groups based on their transcription factors and cytokine production patterns, which mirror helper T-cell subsets. Unlike T cells and B cells, ILCs do not have antigen receptors. They promptly respond to multiple tissue-derived factors, such as cytokines and alarmins, and produce multiple proinflammatory and immunoregulatory cytokines. It has been reported that ILC-derived cytokines are important for the induction and regulation of inflammation. Accumulating evidence suggests that ILCs play substantial roles in protection against infection and the pathogenesis of inflammatory diseases, such as allergic diseases and autoimmune diseases. Different ILC subsets localize in distinct tissue/organ niches and receive tissue-derived signals on different types of inflammation, which allows them to acquire diverse phenotypes with specialized effector capacities. In this review we highlight the roles of ILCs in a variety of organs, such as the airway, skin, and gastrointestinal tract, in the context of allergic and nonallergic inflammation.

Increased frequencies of basophils, type 2 innate lymphoid cells and Th2 cells in skin of patients with atopic dermatitis but not psoriasis

BACKGROUND

Pathogenesis of atopic dermatitis (AD) involves interaction between type 2 cells that include basophils, mast cells, innate lymphoid type 2 cells (ILC2), and Th2 cells. Levels of IL-4 and IL-13 are elevated in AD patients.

OBJECTIVE

Here, we investigated the distribution of type 2 cells and the source of IL-4 and IL-13 in skin and blood of AD relative to psoriasis.

METHODS

Lesional skin biopsies and blood were collected from patients. Skin cell suspensions were prepared by mild enzymatic digestion and mechanical dissociation. IL-4 and IL-13 expression was analyzed at single-cell level before or after stimulation using flow cytometry.

RESULTS

Frequencies of basophils, ILC2 and Th2 but not mast cells were significantly elevated in skin, and not blood, of AD relative to psoriasis. IL-4 production by circulating basophils and Th2 cells, and IL-13 by ILCs and Th2 cells was similar in both diseases. In contrast, skin T cells expressed IL-4 and IL-13 prior to stimulation in AD when compared to psoriasis. Moreover, skin basophils, which were detected in AD only, expressed IL-4 following stimulation. Interestingly, basophils and ILC2 were positively correlated in skin, whereas skin basophils were inversely correlated with blood ILC2.

CONCLUSIONS

Lesional AD skin harbors a distinctive innate and adaptive type 2 profile, which is characterized by basophils producing IL-4, Th2 cells expressing IL-4 or IL-13, and ILC2. This underlies the therapeutic efficacy of targeting IL-4 and IL-13 signaling pathways in AD.

The etiopathogenesis of atopic dermatitis: barrier disruption, immunological derangement, and pruritus

Atopic dermatitis (AD) is a common chronic skin inflammatory disorder characterized by recurrent eczema accompanied by an intractable itch that leads to an impaired quality of life. Extensive recent studies have shed light on the multifaceted pathogenesis of the disease. The complex interplay among skin barrier deficiency, immunological derangement, and pruritus contributes to the development, progression, and chronicity of the disease. Abnormalities in filaggrin, other stratum corneum constituents, and tight junctions induce and/or promote skin inflammation. This inflammation, in turn, can further deteriorate the barrier function by downregulating a myriad of essential barrier-maintaining molecules. Pruritus in AD, which may be due to hyperinnervation of the epidermis, increases pruritogens, and central sensitization compromises the skin integrity and promotes inflammation. There are unmet needs in the treatment of AD. Based on the detailed evidence available to date, certain disease mechanisms can be chosen as treatment targets. Numerous clinical trials of biological agents are currently being conducted and are expected to provide treatments for patients suffering from AD in the future. This review summarizes the etiopathogenesis of the disease and provides a rationale for choosing the novel targeted therapy that will be available in the future.

The prognostic role of serum eosinophil and basophil levels in sinonasal polyposis

BACKGROUND

Predicting which patients are at a higher risk for recurrent chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the most challenging problems in clinical rhinology. A direct association between CRSwNP recurrence rates and serum eosinophil and basophil counts was reported. This study aimed to identify best-fitting cutoffs for binarizing preoperative serum eosinophils and basophils (counts/percentages) for prognostic purposes in cases of CRSwNP recurrence after surgery. A secondary endpoint was to distinguish said cutoffs for prognosticating recurrence in subcohorts of patients with histologically diagnosed eosinophilic/non-eosinophilic CRSwNP.

METHODS

A retrospective study was performed on 280 patients (127 eosinophilic and 153 non-eosinophilic CRSwNP) examining the prognostic role of serum eosinophil and basophil levels.

RESULTS

For all patients examined, mean preoperative serum eosinophil and basophil levels were significantly higher in patients whose CRSwNP recurred. Patients with eosinophil counts ≥0.24 cells × 10⁹ /L and percentages ≥3.7% had odds ratios (ORs) of 2.57 and 2.19 for recurrence; patients with basophil counts ≥0.03 cells × 10⁹ /L and percentages ≥0.5% had ORs of 2.19 and 2.24, respectively. Among histologically eosinophilic CRSwNP patients, mean eosinophils and basophils (counts/percentages) were significantly higher in cases that recurred. Serum eosinophil and basophil values were directly correlated. The recurrence odds were OR 2.52 for high eosinophils (≥5.9%), and OR 2.52 and 2.69 for high basophils (≥0.04 cells × 10⁹ /L and ≥0.5%, respectively).

CONCLUSION

High serum eosinophil and basophil values should be further investigated because they could pinpoint patients at higher risk of eosinophilic-type CRSwNP recurrence. These preliminary results support the increasing interest in the role of basophils in CRSwNP.