Th2 cells and macrophages cooperatively induce allergic inflammation through histamine signaling

Shuteria involucrata alleviates OVA-induced asthma through the TLR4/NF-κB pathway

The roots of Shuteria involucrata (Wall.) Wight & Arn., known as "Tong-qian-ma-huang" in Dai folk medicine in China, are renowned for their efficacy in treating asthma. Despite the use of S. involucrata has been reported as ameliorating respiratory diseases, its mechanism of action remains unclear. This work described the effect of ethyl acetate extract of S. involucrate (SSE) on allergic asthma and its potential mechanism of action was assessed. Ovalbumin was used in vivo to establish a BALB/c asthma mouse model. Lipopolysaccharide was used in vitro to stimulate the human macrophage cell line THP-1 to establish an inflammatory model. In vivo and in vitro experiments showed that SSE effectively ameliorated pathological symptoms and attenuated airway inflammation and cellular inflammation in allergic asthma mice, with a mechanism of action potentially associated to the inhibition of the TLR4/NF-κB signaling pathway.

Macrophage-mediated activation of the IL4I1/AhR axis is a key player in allergic rhinitis

BACKGROUND

Epidemiological evidence suggests that environmental pollutants precipitate the occurrence of allergic rhinitis (AR). The aryl hydrocarbon receptor (AhR), a receptor or sensor for various contaminants, is closely related to immunomodulation and the polarization of M2 macrophages. However, the mechanisms involving AhR and M2 macrophages in AR remain unclear.

METHODS

Bioinformatics analysis of GEO datasets (GSE180697 and GSE180697) assessed AhR and IL4I1 expression levels, which were then verified in the nasal mucosa, monocytes and serum of patients with AR using western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). Primary human mononuclear cells were isolated from peripheral blood using a magnetic separation technique, and THP-1 cell lines with IL4I1 overexpression or downexpression were established through lentiviral constructs. M2 macrophages were induced with the cytokines CSF, IL4 and IL13 and then treated with the AhR agonist FICZ or inhibitor CH223191. The polarization of M2 macrophages was measured by flow cytometry and western blotting. Furthermore, primary nasal epithelial cells and macrophages were co-cultured to assess the epithelial-mesenchymal transition (EMT) in epithelial cells. The AR murine model was established using ovalbumin (OVA). Inflammation within the nasal mucosa and lung tissue was examined after CH223191 or IL4I1 treatment.

RESULTS

Nuclear translocation of AhR and upregulation of IL4I1 was observed in peripheral mononuclear cells and nasal mucosal tissue of patients with AR. Through the activation of AhR, IL4I1 promoted M2 macrophage polarization. Furthermore, modulation of the IL4I1/AhR axis regulated the migratory impact of OVA on T-M2 cells. The IL4I1/AhR axis was involved in the regulation of M2 macrophage-associated EMT and contributed to the expression of IL-33 and STAT6 phosphorylation in epithelial cells. In AR mice, increased AhR nuclear translocation and higher expression of IL4I1 and the M2 macrophage marker CD206 in the lungs was observed. The IL4I1/AhR axis exacerbated allergic symptoms in AR mice, fostering allergic inflammation within the nasal mucosa and lungs.

CONCLUSIONS

The IL4I1/AhR axis is activated within the mononuclear phagocyte system of patients with AR. This activation facilitates the polarization of mononuclear cells into M2 macrophages, which further aggravates EMT in epithelial cells and exacerbates inflammation in AR. This study may provide novel strategies for the precise treatment of AR.

Pathogenesis and Key Cells in Allergic Rhinitis

BACKGROUND

Allergic rhinitis (AR) is one of the most common chronic diseases worldwide, with prevalence rates as high as 50% in high-income countries. Patients with AR often have symptoms such as runny nose, itchy nose, nasal congestion, sneezing, and signs of edema and pallor of the nasal mucosa, and these pathologies have a major impact on the patient's learning, sleep, and quality of life, often resulting in significant pain and a huge economic burden for the patient.

SUMMARY

Among the current treatments for AR, immunotherapy is able to achieve satisfactory clinical outcomes. This shows the importance of immune cells in AR. However, current therapies do not provide a complete cure for AR. The reason for this is that current research on AR focuses on the mechanism of Th1 and Th2 immune cells in AR, ignoring the role of other key cells in AR.

KEY MESSAGES

Group 2 innate lymphoid cells, B cells, T cells, and macrophages can play a role in the pathogenesis of AR by producing appropriate cytokines and mediating the inflammatory response. M2 macrophages can promote Th2 cells and eosinophils in AR to enhance the type 2 inflammatory response and further promote AR.

Opportunities and challenges in the therapeutic exploitation of histamine and histamine receptor pharmacology in inflammation-driven disorders

Inflammation-driven diseases encompass a wide array of pathological conditions characterised by immune system dysregulation leading to tissue damage and dysfunction. Among the myriad of mediators involved in the regulation of inflammation, histamine has emerged as a key modulatory player. Histamine elicits its actions through four rhodopsin-like G-protein-coupled receptors (GPCRs), named chronologically in order of discovery as histamine H1, H2, H3 and H4 receptors (H1-4R). The relatively low affinity H1R and H2R play pivotal roles in mediating allergic inflammation and gastric acid secretion, respectively, whereas the high affinity H3R and H4R are primarily linked to neurotransmission and immunomodulation, respectively. Importantly, however, besides the H4R, both H1R and H2R are also crucial in driving immune responses, the H2R tending to promote yet ill-defined and unexploited suppressive, protective and/or resolving processes. The modulatory action of histamine via its receptors on inflammatory cells is described in detail. The potential therapeutic value of the most recently discovered H4R in inflammatory disorders is illustrated via a selection of preclinical models. The clinical trials with antagonists of this receptor are discussed and possible reasons for their lack of success described.

The function and mechanism of Human nasal mucosa-derived mesenchymal stem cells in allergic rhinitis in mice

PURPOSE

To investigate the immunomodulatory effects and potential mechanisms of human nasal mucosa-derived mesenchymal stem cells(hNMSCs) on mouse allergic rhinitis, and to compare them with human umbilical cord-derived mesenchymal stem cells (hUCMSCs).

METHOD

hNMSCs and hUCMSCs were isolated and cultured for identification from human nasal mucosa and umbilical cord tissues. A co-culture system of LPS-stimulated RAW264.7 cells/mouse peritoneal macrophages and MSCs was employed.Changes in inflammatory factors in RAW264.7 cells and the culture medium as well as the expression of NF-κB signaling pathway in RAW264.7 cells were detected. Forty-eight BALB/c mice were randomly divided into control, OVA, hNMSCs, and hUCMSCs groups. An allergic rhinitis (AR) model was established through ovalbumin (OVA) stimulation and treated with hNMSCs and hUCMSCs. Subsequent assessments included related symptoms, biological changes, and the expression of the NF-κB signaling pathway in the nasal mucosa of mice.

RESULTS

MSCs can be successfully isolated from human nasal mucosa. Both hNMSCs and hUCMSCs interventions significantly reverseed the inflammation induced by LPS and suppressed the upregulation of the NF-κB signaling pathway in RAW264.7 cells. Treatment with hNMSCs and hUCMSCs alleviated mouse allergic symptoms, reduced levels of total IgE, OVA-specific IgE and IgG1 in mouse serum, TH2-type cytokines and chemokines in mouse nasal mucosa, and TH2-type cytokines in mouse spleen culture medium, while also inhibiting the expression of the NF-κB signaling pathway in the nasal mucosa of mice. moreover, the hNMSCs group showed a more significant reduction in OVA-specific IgG1 in serum and IL-4 expression levels in mouse spleen culture medium compared to the hUCMSCs group.

CONCLUSION

Our findings suggest that hNMSCs can ameliorate allergic rhinitis in mice, with a certain advantage in anti-inflammatory effects compared to hUCMSCs. The NF-κB pathway is likely involved in the anti-inflammatory regulation process by hNMSCs.Therefore, hNMSCs might represent a novel therapeutic approach for allergic rhinitis.

The macrophage polarization in allergic responses induced by tropomyosin of Macrobrachium nipponense in cell and murine models

Macrophages are one of the important immune cells, which play important roles in innate and adaptive immune. However, the roles of macrophages in food allergy are not thoroughly understood. To investigate the roles of macrophages during food allergy, we focused on the relationship between macrophage polarization and allergic responses induced by tropomyosin (TM) in the present study. Arg 1 and CD206 expressions in the TM group were significantly higher than those of the PBS group, while iNOS and TNF-α expressions were no obvious difference, moreover, the morphology of macrophages stimulated by TM was similar to that of M2 macrophages. These results indicated macrophages were mainly polarized toward M2 phenotypes in vitro. The antibodies, mMCP-1, histamine and cytokines, revealed that macrophages could participate in food allergy, and macrophage polarization was associated with changes in allergic-related factors. The cytokine levels of M2 phenotypes were significantly higher than those of M1 phenotypes in peripheral blood. The mRNA expressions and protein levels of Arg1 and iNOS in the jejunum and peritoneal cells indicated that M2 phenotypes were the major macrophage in these tissues compared with M1 phenotypes. Hence, macrophage polarization plays an important role in food allergy.

Immune Dysregulation, Inflammation in Characterizing Women with Vulvodynia, Depression, and Both

Background: Depression and vulvodynia are often comorbid. The onset of depression and vulvodynia may be immune and/or stress/environmentally induced. We explored whether vulvodynia, depression, or both occur in response to a Th1-mediated versus Th2-mediated immune response. Materials and Methods: We analyzed data from a case-control study of clinically confirmed vulvodynia and history of depression determined through structured clinical interviews. Immune dysregulation and inflammation were categorized based on the following self-reported conditions: rheumatoid arthritis, Sjogren's disease, scleroderma, systemic lupus erythematosus, inflammatory bowel disease, fibromyalgia, osteoarthritis, polycystic ovarian syndrome, diabetes mellitus, uterine fibroids, asthma, atopic dermatitis, and allergic rhinitis. Logistic regression analyses were adjusted for marital status, body mass index, age, and pack years. Results: Women with systemic immune dysregulation had higher odds of depression (adjusted odds ratio [aOR] = 1.61, confidence interval [95% CI]: 0.65-3.98), vulvodynia (aOR = 2.45, 95% CI: 1.00-5.96), and comorbid depression and vulvodynia (aOR = 4.93, 95% CI: 2.19-11.10) versus neither condition. Women reporting local immune dysregulation had similar odds of depression (aOR = 1.89, 95% CI: 0.99-3.59), vulvodynia (aOR = 2.12, 95% CI: 1.08-4.18), and comorbid depression and vulvodynia (aOR = 1.96, 95% CI: 0.98-3.90). Women with Th2 inflammation had similar odds of depression (aOR = 2.23, 95% CI: 1.05-4.77) and vulvodynia (aOR = 2.56, 95% CI: 1.20-5.49). Women with Th1 or Th2 inflammation had similar odds of comorbid depression and vulvodynia (aOR = 3.03, 95% CI: 1.48-6.19; aOR = 3.14, 95% CI: 1.49-6.60, respectively). Conclusions: Our results suggest that an imbalance of cytokines, indicated by the presence of one or more immune-related health conditions, is associated with an increased risk of vulvodynia and/or depression.

IL-12p40 Monomer: A Potential Player in Macrophage Regulation

Macrophages are myeloid phagocytic leukocytes whose functions are to protect against infections, mediate T-cell responses, and maintain tissue homeostasis. IL-12p40 monomer is a cytokine that is largely produced by macrophages, and it has, for the longest time, been considered a largely non-functional cytokine of the IL-12 family. However, new research has emerged that demonstrates that this p40 monomer may play a bigger role in shaping immune environments. To shed light on the specific effects of p40 monomer on macrophages and their surrounding environment, we showed, through cell culture studies, qPCR, ELISA, and immunofluorescence analyses, that the direct administration of recombinant p40 monomer to RAW 264.7 cells and primary lung macrophages stimulated the production of both pro-inflammatory (TNFα) and anti-inflammatory (IL-10) signals. Accordingly, p40 monomer prevented the full pro-inflammatory effects of LPS, and the neutralization of p40 monomer by mAb a3-3a stimulated the pro-inflammatory effects of LPS. Furthermore, we demonstrated that the intranasal administration of p40 monomer upregulated TNFα+IL-10+ macrophages in vivo in the lungs of mice. Collectively, these results indicate an important immunoregulatory function of p40 monomer in the upregulation of both pro- and anti-inflammatory molecules in macrophages.

Anti-Inflammatory Effects of the LK5 Herbal Complex on LPS- and IL-4/IL-13-Stimulated HaCaT Cells and a DNCB-Induced Animal Model of Atopic Dermatitis in BALB/c Mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease influenced by a complex interplay of genetic and environmental factors. The activation of the JAK-STAT pathway increases the expression of inflammatory cytokines such as IL-4 and IL-13, further deteriorating AD. Therefore, for the treatment of AD, the JAK-STAT pathway is emerging as a significant target, alongside inflammatory cytokines. This study investigates the potential therapeutic effects of a novel herbal complex, LK5, composed of Scutellaria baicalensis, Liriope platyphylla, Sophora flavescens, Dictammus dasycarpus, and Phellodendron schneider, known for their anti-inflammatory and immune-modulating properties. We examined the anti-inflammatory and anti-AD effects of the LK5 herbal complex in HaCaT cells stimulated by LPS and IL-4/IL-13, as well as in a mouse model of AD induced by DNCB. In HaCaT cells stimulated with LPS or IL-4/IL-13, the LK5 herbal complex demonstrated anti-inflammatory effects by inhibiting the expression of inflammatory cytokines including TNF-α, IL-6, and IL-1β, and downregulating the phosphorylation of STAT proteins. In a murine AD-like model induced by DNCB, administration of the LK5 herbal complex significantly ameliorated clinical symptoms, including dermatitis, ear thickness, and TEWL. Histological analysis revealed a reduction in epidermal thickness and mast cell infiltration. The LK5 herbal complex also inhibited pruritus induced by compound 48/80. Furthermore, the LK5 herbal complex treatment significantly decreased the levels of inflammatory cytokines such as TSLP, IL-6, and IgE in plasma and ear tissue of AD-induced mice. These findings suggest that the LK5 herbal complex may modulate the immune response and alleviate AD symptoms by inhibiting STAT pathways.

The relationship between exposure to environmental noise and risk of atopic dermatitis, asthma, and allergic rhinitis

BACKGROUND

Noise is defined as unwanted sound. It may induce negative emotions and mental health problems and may even lead to increased suicide risk. However, the impact of noise exposure on environmental diseases and disease severity is not well understood. This study aimed to elucidate the association between night-time noise exposure and the prevalence of environmental diseases in South Korea.

METHODS

We conducted an analysis of the Environmental Disease Database provide by the National Health Insurance Service (NHIS) from 2013 to 2017. After spatially interpolating the noise data provided by the National Noise Information System (NNIS), night-time noise values in the district level were obtained by calculating the mean noise values at the administrative district level. The linear regression analyses were performed to test the association between the age-standardized prevalence ratio (SPR) and the night-time noise exposure in the district level.

RESULTS

In areas with high night-time noise exposure (≥55 dB), the SPR for atopic dermatitis and allergic rhinitis were 1.0515 (95 % confidence interval [CI]:1.0508-1.0521) and 1.0202 (95 % CI:1.0201-1.0204), respectively, which were higher than those in the general population. The SPR for environmental diseases, including atopic dermatitis, asthma, and allergic rhinitis, was 1.0104 (95 % CI:1.0103-1.0105). Additionally, a significant linear association was observed between the level of nocturnal noise exposure and the total hospitalization period for atopic dermatitis (β = 399.3, p < 0.01).

CONCLUSION

We provide evidence of a significant association between night-time environmental noise and environmental diseases, particularly atopic dermatitis and allergic rhinitis. Furthermore, we observed a significant linear association between night-time noise exposure and the severity of atopic dermatitis.

Variants in transient receptor potential channels and toll-like receptors modify airway responses to allergen and air pollution: a randomized controlled response human exposure study

BACKGROUND

Environmental co-exposure to allergen and traffic-related air pollution is common globally and contributes to the exacerbation of respiratory diseases. Individual responses to environmental insults remain variable due to gene-environment interactions.

OBJECTIVE

This study examined whether single nucleotide polymorphisms (SNPs) in lung cell surface receptor genes modifies lung function change and immune cell recruitment in allergen-sensitized individuals exposed to diesel exhaust (DE) and allergen.

METHODS

In this randomized, double-blinded, four-arm, crossover study, 13 allergen-sensitized participants underwent allergen inhalation challenge following a 2-hour exposure to DE, particle-depleted diesel exhaust (PDDE) or filtered air (FA). Lung function tests and bronchoscopic sample collection were performed up to 48 h after exposures. Transient receptor potential channel (TRPA1 and TRPV1) and toll-like receptor (TLR2 and TLR4) risk alleles were used to construct an unweighted genetic risk score (GRS). Exposure-by-GRS interactions were tested using mixed-effects models.

RESULTS

In participants with high GRS, allergen exposure was associated with an increase in airway hyperresponsiveness (AHR) when co-exposed to PDDE (p = 0.03) but not FA or DE. FA and PDDE also were associated with a relative increase in macrophages and decrease in lymphocytes in bronchoalveolar lavage.

CONCLUSIONS

TRPs and TLRs variants are associated with increased AHR and altered immune cellularity in allergen-exposed individuals. This effect is blunted by DE exposure, suggesting greater influence of unmeasured gene variants as primary meditators of a particulate-rich co-exposure.

TRIAL REGISTRATION

The study was registered with ClinicalTrials.gov on December 20, 2013 (NCT02017431).

Koumine alleviates rheumatoid arthritis by regulating macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

The imbalance between M1-and M2-polarized macrophages is one of the major pathophysiological changes in RA. Therefore, targeted macrophage polarization may be an effective therapy for RA. Koumine, an alkaloid monomer with the highest content and low toxicity in Gelsemium elegans Benth., has the effect of treating RA by playing an immunomodulatory role by influencing various immune cells. However, whether koumine affects macrophage polarization in RA and the associated molecular mechanisms remain unknown.

AIM OF THE STUDY

To investigate the mechanism of the anti-RA effect of koumine on macrophage polarization.

MATERIALS AND METHODS

The effect of koumine on macrophage polarization was investigated in vivo and in vitro. We first explored the effects of koumine on AIA rats and detected the levels of M1/M2 macrophage polarization markers in the spleen by western blotting. Then, we explored the regulatory effect of koumine on M1/M2 macrophage polarization and the effect on the PI3K/AKT signaling pathway in vitro. Finally, we verified the effects of koumine on macrophage polarization in CIA mice.

RESULTS

We found that koumine alleviated symptoms, including relieving pain, reducing joint redness and swelling in AIA rats and restoring the M1/M2 macrophage balance in vivo. Interestingly, koumine had an inhibitory effect on both M1 and M2 macrophage polarization in vitro, but it had a stronger inhibitory effect on M1 macrophage. In a mixed polarization experiment, koumine mainly inhibited M1 macrophage polarization and had an inhibitory effect on the PI3K/AKT signaling pathway. Finally, we found that koumine had therapeutic effects on CIA mice, regulated macrophage polarization and inhibited the PI3K/AKT signaling pathway.

CONCLUSIONS

Our results reveal that koumine regulates macrophage polarization through the PI3K/AKT signaling pathway. This may be one of the important mechanisms of its anti-RA effect, which provides a theoretical and scientific basis for the possible clinical application of koumine.

Innate and Adaptive Immunity during SARS-CoV-2 Infection: Biomolecular Cellular Markers and Mechanisms

The coronavirus 2019 (COVID-19) pandemic was caused by a positive sense single-stranded RNA (ssRNA) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, other human coronaviruses (hCoVs) exist. Historical pandemics include smallpox and influenza, with efficacious therapeutics utilized to reduce overall disease burden through effectively targeting a competent host immune system response. The immune system is composed of primary/secondary lymphoid structures with initially eight types of immune cell types, and many other subtypes, traversing cell membranes utilizing cell signaling cascades that contribute towards clearance of pathogenic proteins. Other proteins discussed include cluster of differentiation (CD) markers, major histocompatibility complexes (MHC), pleiotropic interleukins (IL), and chemokines (CXC). The historical concepts of host immunity are the innate and adaptive immune systems. The adaptive immune system is represented by T cells, B cells, and antibodies. The innate immune system is represented by macrophages, neutrophils, dendritic cells, and the complement system. Other viruses can affect and regulate cell cycle progression for example, in cancers that include human papillomavirus (HPV: cervical carcinoma), Epstein-Barr virus (EBV: lymphoma), Hepatitis B and C (HB/HC: hepatocellular carcinoma) and human T cell Leukemia Virus-1 (T cell leukemia). Bacterial infections also increase the risk of developing cancer (e.g., Helicobacter pylori). Viral and bacterial factors can cause both morbidity and mortality alongside being transmitted within clinical and community settings through affecting a host immune response. Therefore, it is appropriate to contextualize advances in single cell sequencing in conjunction with other laboratory techniques allowing insights into immune cell characterization. These developments offer improved clarity and understanding that overlap with autoimmune conditions that could be affected by innate B cells (B1+ or marginal zone cells) or adaptive T cell responses to SARS-CoV-2 infection and other pathologies. Thus, this review starts with an introduction into host respiratory infection before examining invaluable cellular messenger proteins and then individual immune cell markers.

Expected impact of immunomodulatory agents during pregnancy: A newborn's perspective

The neonatal immune ontogeny begins during pregnancy to ensure that the neonate is well-suited for perinatal life. It prioritizes Th2/M2 and regulatory responses over Th/M1 activity to avoid excessive inflammatory responses and to ensure immune tolerance and homeostasis. Newborns also present increased Th17/Th22 responses providing effective anti-fungal immunity and mucosal protection. Intrauterine exposure to immune modulatory drugs with the placental transfer may influence the natural course of the fetal immune development. The vertical transfer of both biological therapy and small molecules begins during the first trimester through neonatal Fc receptor or placental diffusion, respectively, reaching its maximum transfer potential during the third trimester of pregnancy. Most of the biological therapy have a prolonged half-life in newborn's blood, being detectable in infants up to 12 months after birth (usually 6-9 months). The use of immunomodulators during pregnancy is gaining global interest. Current evidence mainly reports birth-related outcomes without exhaustive analysis of the on-target side effect on the perinatal immune system ontogeny, the infection risk, or the immune dysregulation. The present review will focus on: (1) the main characteristics of the perinatal immune system to understand its specific features and vulnerabilities to immune modulation; (2) the mechanisms of placental transfer of immunomodulators; and (3) the immune changes reported to date in newborns exposed to immunomodulators with emphasis on the current concerns and gaps in knowledge.

Aryl hydrocarbon receptor: The master regulator of immune responses in allergic diseases

The aryl hydrocarbon receptor (AhR) is a widely studied ligand-activated cytosolic transcriptional factor that has been associated with the initiation and progression of various diseases, including autoimmune diseases, cancers, metabolic syndromes, and allergies. Generally, AhR responds and binds to environmental toxins/ligands, dietary ligands, and allergens to regulate toxicological, biological, cellular responses. In a canonical signaling manner, activation of AhR is responsible for the increase in cytochrome P450 enzymes which help individuals to degrade and metabolize these environmental toxins and ligands. However, canonical signaling cannot be applied to all the effects mediated by AhR. Recent findings indicate that activation of AhR signaling also interacts with some non-canonical factors like Kruppel-like-factor-6 (KLF6) or estrogen-receptor-alpha (Erα) to affect the expression of downstream genes. Meanwhile, enormous research has been conducted to evaluate the effect of AhR signaling on innate and adaptive immunity. It has been shown that AhR exerts numerous effects on mast cells, B cells, macrophages, antigen-presenting cells (APCs), Th1/Th2 cell balance, Th17, and regulatory T cells, thus, playing a significant role in allergens-induced diseases. This review discussed how AhR mediates immune responses in allergic diseases. Meanwhile, we believe that understanding the role of AhR in immune responses will enhance our knowledge of AhR-mediated immune regulation in allergic diseases. Also, it will help researchers to understand the role of AhR in regulating immune responses in autoimmune diseases, cancers, metabolic syndromes, and infectious diseases.

The Effects of Saposhnikovia divaricata Aqueous Extracts on the Inflammation and Intestinal Microflora in Allergic Rhinitis Mice

Background

Allergic rhinitis (AR) is a type I allergic disease induced by IgE. Traditional Chinese medicine Saposhnikovia divaricata (Turcz.) Schischk (SD) has anti-inflammatory and antiallergic effects.

Materials and Methods

AR model mice were constructed with ovalbumin (OVA) sensitization to observe the improving effect of SD treatment on AR by counting the number of sneezing and rubbing the nose, hematoxylin-eosin, periodic acid-Schiff, and toluidine blue stains. In addition, the allergy and inflammatory cytokines levels and inflammatory cells were observed by ELISA and Wright's-Giemsa stain. The protein levels of the TLR4/TRAF6/NF-κB and IL-6/ROR-γt/STAT3 pathways were measured by immunohistochemistry, quantitative real-time PCR, and western blot. The intestinal microflora abundance in mice was observed by 16S rDNA high-throughput sequencing.

Results

SD treatment inhibited the sneezing and rubbing times of the nose, decreased the degree of a dense arrangement of cells and mucosal swelling and the number of goblet and mast cells of nasal lavage fluid, reduced the levels of IgE, histamine, Leukotriene B4, IL-4, IL-5, TNF-α, IL-6, and IL-17, the eosinophils, neutrophils, and lymphocytes number, the LR4, TRAF6, IL-6, ROR-γt, and STAT3 mRNA levels, respectively, while, it increased the IL-2, IL-10, IFN-γ, and TGF-β1 proteins. SD treatment inhibited the NF-κB, p-STAT3, TLR4, TRAF6, and p-IκBα/IκBα proteins. Besides, the effects of OVA and SD treatments were significantly correlated with the abundance of intestinal microflora. The abundances of Cytophagales, Burkholderia, Alteromonadales, Lactococcus, and Clostridiaceae were changed in SD treatment on AR mice.

Conclusions

This study provides a possibility that the improvement effect of SD treatment on allergies and inflammation in AR mice may be related to the TLR4/TRAF6/NF-κB and IL-6/ROR-γt/STAT3 pathways and intestinal microflora modulation.

Allergic Rhinitis: Pathophysiology and Treatment Focusing on Mast Cells

Allergic rhinitis (AR) is a common rhinopathy that affects up to 30% of the adult population. It is defined as an inflammation of the nasal mucosa, develops in allergic individuals, and is detected mostly by a positive skin-prick test. AR is characterized by a triad of nasal congestion, rhinorrhea, and sneezing. Mast cells (MCs) are innate immune system effector cells that play a pivotal role in innate immunity and modulating adaptive immunity, rendering them as key cells of allergic inflammation and thus of allergic diseases. MCs are typically located in body surfaces exposed to the external environment such as the nasal mucosa. Due to their location in the nasal mucosa, they are in the first line of defense against inhaled substances such as allergens. IgE-dependent activation of MCs in the nasal mucosa following exposure to allergens in a sensitized individual is a cardinal mechanism in the pathophysiology of AR. This review is a comprehensive summary of MCs' involvement in the development of AR symptoms and how classical AR medications, as well as emerging AR therapies, modulate MCs and MC-derived mediators involved in the development of AR.

Lirentelimab for severe and chronic forms of allergic conjunctivitis

BACKGROUND

Allergic conjunctivitis (AC) is an ocular inflammatory disease with symptoms driven by eosinophils and mast cells. Allergic comorbidities are common. Current treatments are often ineffective in severe AC and limited by potential side effects. Lirentelimab is an anti-sialic acid-binding immunoglobulin-like lectin-8 mAb that depletes eosinophils and inhibits mast cells.

OBJECTIVE

We sought to determine safety and preliminary efficacy of lirentelimab in an open-label, phase 1b study.

METHODS

Patients with chronic, severely symptomatic atopic keratoconjunctivitis, vernal keratoconjunctivitis, and perennial AC, and who had history of topical or systemic corticosteroid use, were enrolled to receive up to 6 monthly lirentelimab infusions (dose 1: 0.3 mg/kg, dose 2: 1 mg/kg, subsequent doses: 1 or 3 mg/kg). Changes from baseline in peripheral blood eosinophils, changes in patient-reported symptoms (measured by daily Allergic Conjunctivitis Symptom Questionnaire, including atopic comorbidities), changes in investigator-reported ocular signs and symptoms (Ocular Symptom Scores), changes in quality of life, and changes in tear cytokine and chemokine levels were assessed.

RESULTS

Thirty patients were enrolled (atopic keratoconjunctivitis n = 13, vernal keratoconjunctivitis n = 1, perennial AC n = 16), 87% of whom had atopic comorbidities. After lirentelimab treatment, mean improvement was observed in Allergic Conjunctivitis Symptom Questionnaire score (-61%; 95% CI, -75% to -48%) and Ocular Symptom Scores (-53%; 95% CI, -76% to -31%), consistent across atopic keratoconjunctivitis, vernal keratoconjunctivitis, and perennial AC groups. There was substantial improvement in atopic comorbidities, with -55% (95% CI, -78% to -31%), -50% (95% CI, -82% to -19%), and -63% (95% CI, -87% and -38%) reduction in symptoms of atopic dermatitis, asthma, and rhinitis, respectively. Levels of key mediators of inflammation were reduced in patient tears after lirentelimab treatment. The most common adverse effects were mild to moderate infusion-related reactions.

CONCLUSIONS

Lirentelimab was well tolerated, improved severe AC and concomitant atopic symptoms, and reduced inflammatory mediators in patient tears.

Circulating MMP-12 as Potential Biomarker in Evaluating Disease Severity and Efficacy of Sublingual Immunotherapy in Allergic Rhinitis

Background

Allergic rhinitis (AR) is a highly heterogeneous disease, and allergen-specific immunotherapy (AIT) is an effective treatment. This study aims to evaluate the circulating mas-related G protein-coupled receptor-X2 (MRGPRX2) and matrix metalloproteinase-12 (MMP-12) levels in evaluating disease severity and predicting efficacy of SLIT in AR patients.

Methods

We enrolled 110 moderate-severe persist AR patients (AR group) and 40 healthy controls (HC group). Circulating levels of MRGPRX2 and MMP-12 were measured, and their associations with disease severity were evaluated. All AR patients were assigned to receive sublingual immunotherapy (SLIT), and the efficacy was evaluated, and serum samples were collected at 1 year and 3 years after treatment. The correlations between serum MRGPRX2 and MMP-12 and clinical efficacy were assessed.

Results

The serum concentrations of MRGPRX2 and MMP-12 were significantly higher in the AR group than the HC group, and the elevated MMP-12 levels were correlated with VAS and TNSS, and serum MRGPRX2 levels were correlated with VAS. Finally, 100 and 80 patients completed 1-year and 3-year follow-up and were classified into effective and ineffective groups. Serum MRGPRX2 and MMP-12 levels were lower in the effective group than the ineffective group. Although serum MRGPRX2 and MMP-12 levels did not significantly change after 1 year SLIT, serum MMP-12 levels were decreased 3 years post-SLIT than baseline and 1 year post-SLIT levels. Receiver operating characteristic (ROC) showed that serum MMP-12 was a potential biomarker for predicting the efficacy of SLIT.

Conclusion

Serum MRGPRX2 and MMP-12 appeared to be promising biological indicators in reflecting disease severity in AR patients. Moreover, circulating MMP-12 might serve as a reliable predictor for clinical responsiveness of SLIT.

How Do Pollen Allergens Sensitize?

Plant pollen is one of the main sources of allergens causing allergic diseases such as allergic rhinitis and asthma. Several allergens in plant pollen are panallergens which are also present in other allergen sources. As a result, sensitized individuals may also experience food allergies. The mechanism of sensitization and development of allergic inflammation is a consequence of the interaction of allergens with a large number of molecular factors that often are acting in a complex with other compounds, for example low-molecular-mass ligands, which contribute to the induction a type 2-driven response of immune system. In this review, special attention is paid not only to properties of allergens but also to an important role of their interaction with lipids and other hydrophobic molecules in pollen sensitization. The reactions of epithelial cells lining the nasal and bronchial mucosa and of other immunocompetent cells will also be considered, in particular the mechanisms of the activation of B and T lymphocytes and the formation of allergen-specific antibody responses.

Interactions between Macrophages and Mast Cells in the Female Reproductive System

Mast cells (MCs) and macrophages (Mϕs) are innate immune cells that differentiate from early common myeloid precursors and reside in all body tissues. MCs have a unique capacity to neutralize/degrade toxic proteins, and they are hypothesized as being able to adopt two alternative polarization profiles, similar to Mϕs, with distinct or even opposite roles. Mϕs are very plastic phagocytic cells that are devoted to the elimination of senescent/anomalous endogenous entities (to maintain tissue homeostasis), and to the recognition and elimination of exogenous threats. They can adopt several functional phenotypes in response to microenvironmental cues, whose extreme profiles are the inflammatory/killing phenotype (M1) and the anti-inflammatory/healing phenotype (M2). The concomitant and abundant presence of these two cell types and the partial overlap of their defensive and homeostatic functions leads to the hypothesis that their crosstalk is necessary for the optimal coordination of their functions, both under physiological and pathological conditions. This review will examine the relationship between MCs and Mϕs in some situations of homeostatic regulation (menstrual cycle, embryo implantation), and in some inflammatory conditions in the same organs (endometriosis, preeclampsia), in order to appreciate the importance of their cross-regulation.

Characteristics of allergen profile, sensitization patterns and Allergic Rhinitis in SouthEast Asia

PURPOSE OF REVIEW

To highlight the characteristics of allergic rhinitis, local allergic rhinitis (LAR), and importance of allergens in Southeast Asian countries.

RECENT FINDINGS

The Asia-Pacific region is very diverse with disparities in the epidemiological data between countries as well as in the unmet needs. The prevalence of allergic rhinitis has markedly increased in the past decades, with a high variation between countries, ranging from 4.5--80.3%. In terms of LAR, the reported prevalence in Southeast Asia is similar to that of other Asian countries (3.7-24.9%) but lower than that in western countries. House dust mites, cockroach, pollens, and molds are major allergens that are known triggers for of allergic rhinitis in this region, whereas the association with helminth infection requires further investigation.

SUMMARY

There are gaps and high variation between countries in Southeast Asia regarding the prevalence of allergic rhinitis and LAR. Further studies are needed to fully elucidate the association between allergens and allergic rhinitis in Southeast Asia.

COVID-19 pandemic: the delta variant, T-cell responses, and the efficacy of developing vaccines

Background

The mayhem COVID-19 that was ushered by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) was declared pandemic by the World Health Organization in March 2020. Since its initial outbreak in late 2019, the virus has affected hundreds of million adults in the world and killing millions in the process. After the approval of newly developed vaccines, severe challenges remain to manufacture and administer them to the adult population globally in quick time. However, we have witnessed several mutations of the virus leading to ‘waves’ of viral spread and mortality. WHO has categorized these mutations as variants of concern (VOCs) and variants of interest (VOIs). The mortality due to COVID-19 has also been associated with various comorbidities and improper immune response. This has created further complications in understanding the nature of the SARS-CoV2–host interaction that has fuelled doubts in the efficacy of the approved vaccines. Whether there is requirement of booster dose and whether the impending wave could affect the children are some of the hotly debated topics.

Materials and Methods

A systematic literature review of PubMed, Medline, Scopus, Google Scholar was utilized to understand the nature of Delta variant and how it alters our T-cell responses and cytokine production and neutralizes vaccine-generated antibodies.

Conclusion

In this review, we discuss the variants of SARS-CoV2 with specific focus on the Delta variant. We also specifically review the T-cell response against the virus and bring a narrative of various factors that may hold the key to fight against this marauding virus.

The Flagellin:Allergen Fusion Protein rFlaA:Betv1 Induces a MyD88- and MAPK-Dependent Activation of Glucose Metabolism in Macrophages

TLR5 ligand flagellin-containing fusion proteins are potential vaccine candidates for many diseases. A recombinant fusion protein of flagellin A and the major birch pollen allergen Bet v 1 (rFlaA:Betv1) modulates immune responses in vitro and in vivo. We studied the effects of rFlaA:Betv1 on bone marrow-derived macrophages (BMDMs). BMDMs differentiated from BALB/c, C57BL/6, TLR5^-/-, or MyD88^-/- mice were pre-treated with inhibitors, stimulated with rFlaA:Betv1 or respective controls, and analyzed for activation, cytokine secretion, metabolic state, RNA transcriptome, and modulation of allergen-specific Th2 responses. Stimulation of BMDMs with rFlaA:Betv1 resulted in MyD88-dependent production of IL-1β, IL-6, TNF-α, IL-10, CD69 upregulation, and a pronounced shift towards glycolysis paralleled by activation of MAPK, NFκB, and mTOR signaling. Inhibition of either mTOR (rapamycin) or SAP/JNK-MAPK signaling (SP600125) resulted in dose-dependent metabolic suppression. In BMDM and T cell co-cultures, rFlaA:Betv1 stimulation suppressed rBet v 1-induced IL-5 and IL-13 secretion while inducing IFN-γ production. mRNA-Seq analyses showed HIF-1a, JAK, STAT, phagosome, NLR, NFκB, TNF, TLR, and chemokine signaling to participate in the interplay of cell activation, glycolysis, and immune response. rFlaA:Betv1 strongly activated BMDMs, resulting in MyD88-, MAPK-, and mTOR-dependent enhancement of glucose metabolism. Our results suggest macrophages are important target cells to consider during restauration of allergen tolerance during AIT.

Th2 cell-derived histamine is involved in nasal Th2 infiltration in mice

OBJECTIVE

Histamine derived from mast cells and basophils plays important roles in inducing allergic symptoms. Although T cells also produce histamine, the involvement of the histamine produced from T cells has remained enigmatic. We sought to reveal the roles of T helper 2 (Th2) cell-derived histamine in nasal allergic disorders.

METHODS

The histamine production from Th2 cells was measured by EIA. The mRNA expression of histidine decarboxylase (HDC) was measured by real-time PCR. To investigate the roles of Th2 cell-derived histamine in vivo, we analyzed an antigen-specific Th2 cell transfer mouse model.

RESULTS

Th2 cells produced histamine by T cell receptor stimulation, and these properties were specific for Th2 cells, but not Th1 cells and naïve CD4 T cells. The histamine produced from Th2 cells was involved in the infiltrations of Th2 cells in response to antigen exposure.

CONCLUSION

These results suggest that Th2 cell-derived histamine play important roles in nasal allergic disorders.

Experimental postoperative ileus: is Th2 immune response involved?

Rationale: Postoperative ileus (POI) is a frequent complication arising after gastrointestinal surgery but pathogenesis of POI is still not fully understood. While Th1 immune cells are implicated in POI, the involvement of Th2 cells has not yet been clarified. Given the impact of reactive oxygen species (ROS) in the regulation of Th1 and Th2 balance, we hypothesized that not only Th1 but also Th2 immune response can be involved in the development of experimental POI. Methods: The intestinal transit test was performed using carbon gum arabic. Electron microscopy was employed to assess tissue morphology and the presence of immune cells. Cytokines, IgE and ROS were measured. Immune cells from Peyer's patches were analyzed by Flow Cytometry and toluidine blue staining was used for detection of mast cells. Transcriptional factors were analyzed by Western blot. Results: POI is associated with an increase in both Th2 cytokines and Th2 cells. We have further demonstrated that POI induces a Th2-dependent activation of memory and non-memory B cells. This was accompanied by an increase in a number of mast cells in the colon of POI mice as well by an increased IgE and histamine plasma levels. We found that POI-induced accumulation of ROS was associated with an increased expression of the transcriptional factors HMBGI, NF-κB, and p38. This increased expression seemed to be associated with a Th2 response. Conclusion: Th2 immune response can be involved in the activation of mast cells in POI, which was associated with ROS mediated activation of NF-κB and p38 MAPK signaling pathway.