Genetic Variation along the Histamine Pathway in Children with Allergic versus Nonallergic Asthma

Combined impacts of histamine receptor H1 gene polymorphisms and an environmental carcinogen on the susceptibility to and progression of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most frequently encountered type of oral cancer. Histamine receptor H1 (HRH1) was reported to play a crucial role in OSCC carcinogenesis, but impacts of genetic variants of HRH1 on OSCC remain unclear. Herein, we investigated the association between functional single-nucleotide polymorphisms (SNPs) of HRH1 and OSCC susceptibility or clinicopathologic variables by logistic regression models. HRH1 genotypes at four loci (rs346074, rs346076, rs901865, and rs2606731) were analyzed by a TaqMan allelic discrimination assay, and we found that patients harboring HRH1 rs901865 T and rs346074 T alleles had a significantly lower risk of developing larger tumor sizes (>T2) under a dominant model. Based on the environmental carcinogen exposure status, we observed that HRH1 rs901865 polymorphic variants were also associated with a lower risk of developing more-advanced clinical stages (III or IV) in patients with a betel-quid-chewing habit. Moreover, genotype screening of rs901865 and rs346074 in OSCC cell lines showed that cells respectively carrying the CT and TT genotypes expressed lower HRH1 levels compared to cells carrying the CC genotype of rs901865 and rs346074. Furthermore, analyses of TCGA and GEO databases revealed that HRH1 expression levels were upregulated in head and neck squamous cell carcinoma (HNSCC) and OSCC tissues compared to normal tissues and were correlated with larger tumor sizes and poorer prognoses. These results indicated the involvement of HRH1 SNPs rs901865 and rs346074 in OSCC development and support the interaction between HRH1 gene polymorphisms and an environmental carcinogen as a predisposing factor for OSCC progression.

Histamine Intolerance-A Kind of Pseudoallergic Reaction

Histamine intolerance (HIT) is a common disorder associated with impaired histamine metabolism. Notwithstanding, it is often misdiagnosed as other diseases because of its lack of specific clinical manifestations. HIT did not gain traction until the early 21st century. In this review, we will focus on the latest research and elaborate on the clinical manifestations of HIT, including its manifestations in special populations such as atopic dermatitis (AD) and chronic urticaria (CU), as well as the latest understanding of its etiology and pathogenesis. In addition, we will explore the latest treatment strategies for HIT and the treatment of specific cases.

Whole transcriptome analysis of high and low IFN-α producers reveals differential response patterns following rhinovirus stimulation

Objectives

Viral respiratory infections cause considerable morbidity and economic loss. While rhinoviruses (RV) typically cause little more than the common cold, they can produce severe infections and disease exacerbations in susceptible individuals, such as those with asthma. Variations in the regulation of key antiviral cytokines, particularly type I interferon (IFN‐α and IFN‐β), may contribute to RV susceptibility. To understand this variability, we compared the transcriptomes of high and low type I IFN producers.

Methods

Blood mononuclear cells from 238 individuals with or without asthma were cultured in the presence or absence of RV. Those samples demonstrating high or low RV‐stimulated IFN‐α production (N = 75) underwent RNA‐sequencing.

Results

Gene expression patterns were similar in samples from healthy participants and those with asthma. At baseline, the high IFN‐α producer group showed higher expression of genes associated with plasmacytoid dendritic cells, the innate immune response and vitamin D activation, but lower expression of oxidative stress pathways than the low IFN‐α producer group. After RV stimulation, the high IFN‐α producer group showed higher expression of genes found in immune response biological pathways and lower expression of genes linked to developmental and catabolic processes when compared to the low IFN‐α producer group.

Conclusions

These differences suggest that the high IFN‐α group has a higher level of immune system readiness, resulting in a more intense and perhaps more focussed pathogen‐specific immune response. These results contribute to a better understanding of the variability in type I IFN production between individuals.

Histamine Intolerance in Children: A Narrative Review

Histamine intolerance is defined as a disequilibrium of accumulated histamine and the capacity for histamine degradation. This clinical term addresses a non-immunologically mediated pathology when histamine ingested with food is not particularly high, however its degradation is decreased. This paper aims to provide a narrative review on etiopathology, epidemiology, possible diagnostic algorithms and diagnostic challenges of histamine intolerance in children. The clinical picture of histamine intolerance in children is similar to that observed in adults apart from male predominance found in paediatric patients. Both in children and adults, a histamine-reduced diet is typically the treatment of choice. Diamine oxidase supplementation offers another treatment option. There is no symptom or test pathognomonic for histamine intolerance. Nevertheless, manifestations of chronic gastrointestinal symptoms, measurements of diamine oxidase deficits, positive results of histamine provocation tests and improvement in symptoms with histamine-reduced diet considerably increase the probability of histamine intolerance diagnosis. These factors have been included in the proposed diagnostic algorithm for histamine intolerance. In children histamine intolerance most likely co-occurs with allergies and bowel diseases, which creates an additional diagnostic challenge. As the evidence for children is poor further research is needed the determine epidemiology, validate diagnostic algorithms and establish possible treatment options regarding histamine intolerance.

Human Copper-Containing Amine Oxidases in Drug Design and Development

Two members of the copper-containing amine oxidase family are physiologically important proteins: (1) Diamine oxidase (hDAO; AOC1) with a preference for diamines is involved in degradation of histamine and (2) Vascular adhesion protein-1 (hVAP-1; AOC3) with a preference for monoamines is a multifunctional cell-surface receptor and an enzyme. hVAP-1-targeted inhibitors are designed to treat inflammatory diseases and cancer, whereas the off-target binding of the designed inhibitors to hDAO might result in adverse drug reactions. The X-ray structures for both human enzymes are solved and provide the basis for computer-aided inhibitor design, which has been reported by several research groups. Although the putative off-target effect of hDAO is less studied, computational methods could be easily utilized to avoid the binding of VAP-1-targeted inhibitors to hDAO. The choice of the model organism for preclinical testing of hVAP-1 inhibitors is not either trivial due to species-specific binding properties of designed inhibitors and different repertoire of copper-containing amine oxidase family members in mammalian species. Thus, the facts that should be considered in hVAP-1-targeted inhibitor design are discussed in light of the applied structural bioinformatics and structural biology approaches.

Impaired resolution of wheals in the skin prick test and low diamine oxidase blood level in allergic patients

Introduction

Histamine is the major mediator of IgE- and non-IgE-mediated allergic reactions upon allergen or hapten contact. Reduced histamine degradation capacity was associated with atopic eczema as well as with non-immunological histamine intolerance. Higher blood serum histamine level concomitant with decreased intestinal diamine oxidase activity were observed in patients with food allergy.

Aim

To evaluate the relationship between patients’ blood diamine oxidase (DAO) activity/histamine status and their reactivity to time-resolved histamine skin prick test in respect to vulnerability to allergic diseases.

Material and methods

Fifty-three patients were examined with skin prick tests (SPT) and patch tests for suspected presence of either IgE- or non-IgE-mediated allergy. All individuals were skin prick tested with histamine and the resolution of the wheal was monitored for 50 min. Blood DAO activity and histamine concentration were measured with a radio-extraction radioimmunoassay.

Results

Time-resolved histamine skin prick testing revealed presence of wheals which were 35% larger in diameter in 47% of examined subjects at 20 min of the test. These patients exhibited significantly compromised time-course wheal resolution (wheal ≥ 3 mm at 50 min) compared to a group of patients with the normal-rate of wheal resolution (wheal = 0 mm at 50 min). Within a group of subjects exhibiting impaired wheal resolution, 61% of patients were diagnosed allergic compared to 50% in a group of patients with a normal rate of wheal resolution. Finally, allergic patients were characterized by a significantly lower DAO activity and higher histamine content compared to healthy subjects.

Conclusions

The results of this study indicate that patients with IgE- or non-IgE-mediated allergy are likely to have low DAO blood activity and may concomitantly suffer from histamine intolerance. Furthermore, our results suggest that allergic patients are more likely to develop an excessive SPT reaction. Our results emphasize caution in interpretation of the SPT results in allergic patients with diagnosed histamine intolerance or histamine/DAO activity imbalance.

Human H1 receptor (HRH1) gene polymorphism is associated with the severity of side effects after desloratadine treatment in Chinese patients with chronic spontaneous uticaria

H1 nonsedating antihistamines, such as desloratadine, are first-line treatment options for chronic spontaneous urticaria (CSU). However, desloratadine induces various degrees of sedation side effect in CSU patients, and no biomarkers currently exist for predicting the severity of such side effect. Herein, we evaluated the association between HRH1 gene rs901865 polymorphism and the severity of sedation side effect following desloratadine therapy in patients with CSU. We found that 20 of the 114 patients (17.50%) showed sedation side effect after desloratadine treatment, and 3 patients (2.63%) experienced serious sleepiness. The frequency of HRH1 rs901865 G allele was significantly higher in patients who experienced sedation than in patients with rs901865 A allele (p = 0.0009). Moreover, patients with the rs901865 G/G genotype suffered a more serious sedation side effect than patients with the rs901865 G/A genotype (p = 0.005). These results provide evidence that the HRH1 rs901865 G/G polymorphism is associated with severe sedation side effect after desloratadine treatment. Thus, the HRH1 rs901865 allele may potentially be used as a biomarker for predicting the severity of sedation side effect in patients suffering from CSU and treated with desloratadine.

The Role of Histamine in the Pathophysiology of Asthma and the Clinical Efficacy of Antihistamines in Asthma Therapy

Mast cells play a critical role in the pathogenesis of allergic asthma. Histamine is a central mediator released from mast cells through allergic reactions. Histamine plays a role in airway obstruction via smooth muscle contraction, bronchial secretion, and airway mucosal edema. However, previous clinical trials of H1 receptor antagonists (H1RAs) as a treatment for asthma were not successful. In recent years, type 2 innate immunity has been demonstrated to be involved in allergic airway inflammation. Allergic asthma is defined by IgE antibody-mediated mast cell degranulation, while group 2 innate lymphoid cells (ILC2) induce eosinophilic inflammation in nonallergic asthma without allergen-specific IgE. Anti-IgE therapy has demonstrated prominent efficacy in the treatment of severe allergic asthmatics sensitized with specific perennial allergens. Furthermore, recent trials of specific cytokine antagonists indicated that these antagonists were effective in only some subtypes of asthma. Accordingly, H1RAs may show significant clinical efficacy for some subtypes of allergic asthma in which histamine is deeply associated with the pathophysiology.

Genetic Mechanisms of Asthma and the Implications for Drug Repositioning

Asthma is a chronic disease that is caused by airway inflammation. The main features of asthma are airway hyperresponsiveness (AHR) and reversible airway obstruction. The disease is mainly managed using drug therapy. The current asthma drug treatments are divided into two categories, namely, anti-inflammatory drugs and bronchodilators. However, disease control in asthma patients is not very efficient because the pathogenesis of asthma is complicated, inducing factors that are varied, such as the differences between individual patients. In this paper, we delineate the genetic mechanisms of asthma, and present asthma-susceptible genes and genetic pharmacology in an attempt to find a diagnosis, early prevention, and treatment methods for asthma. Finally, we reposition some clinical drugs for asthma therapy, based on asthma genetics.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Genetic Variation in the Histamine Production, Response, and Degradation Pathway Is Associated with Histamine Pharmacodynamic Response in Children with Asthma

Introduction: There is growing knowledge of the wide ranging effects of histamine throughout the body therefore it is important to better understand the effects of this amine in patients with asthma. We aimed to explore the association between histamine pharmacodynamic (PD) response and genetic variation in the histamine pathway in children with asthma.

Methods: Histamine Iontophoresis with Laser Doppler Monitoring (HILD) was performed in children with asthma and estimates for area under the effect curve (AUEC), maximal response over baseline (Emax), and time of Emax (Tmax) were calculated using non-compartmental analysis and non-linear mixed-effects model with a linked effect PK/PD model. DNA isolation and genotyping were performed among participants to detect known single nucleotide polymorphisms (SNPs) (n = 10) among genes (HDC, HNMT, ABP1, HRH1, HRH4) within the histamine pathway. General linear model was used to identify associations between histamine related genetic variants and measured histamine PD response parameters.

Results: Genotyping and HILD response profiles were completed for 163 children. ABP1 47 C/T, ABP1 4107, and HNMT-1639 C/Twere associated with Emax (ABP1 47 CC genotype mean Emax 167.21 vs. CT/TT genotype mean Emax 139.20, p = 0.04; ABP1 4107 CC genotype mean Emax 141.72 vs. CG/GG genotype mean Emax 156.09, p = 0.005; HNMT-1639 CC genotype mean Emax 132.62 vs. CT/TT genotype mean Emax 155.3, p = 0.02). In a stratified analysis among African American children only, ABP1 and HNMT SNPs were also associated with PD response; HRH4 413 CC genotype was associated with lower Emax, p = 0.009.

Conclusions: We show for the first time that histamine pathway genetic variation is associated with measureable changes in histamine response in children with asthma. The variability in histamine response and impact of histamine pathway genotype is important to further explore in patients with asthma so as to improve disease phenotyping leading to more personalized treatments.

Genetic variations within the promotor region of the human histamine H4 receptor gene in psoriasis patients

Environmental triggers and genetic factors are supposed to lead to complex gene expression changes in psoriasis and interact in the manifestation of the disease. The histamine H4 receptor (HRH4) is functionally expressed on Th17 cells and plasmacytoid dendritic cells (pDCs) which play a prominent role in the pathogenesis of psoriasis. On pDCs a higher basal expression level of the HRH4 in psoriasis patients compared to healthy controls has been detected. The functional relationship between predisposing genetic variations in the HRH4 gene and psoriasis is yet not known. The aim of the study was to evaluate a possible association between single nucleotide polymorphisms (SNPs) in the HRH4 gene primarily in the promotor region and incidence, severity as well as special clinical features (nail involvement, arthritis, palmoplantar location) of psoriasis. For this approach genomic DNA from 206 patients with psoriasis and 213 healthy controls of Caucasian origin was extracted and three SNPs in the promotor region and one SNP located in an intron of the HRH4 gene were analysed by PCR and pyrophosphate DNA-sequencing. The genotype distributions and allele frequencies between the different groups were compared by chi-square test. The analysis of association between HRH4 polymorphisms and psoriasis was assessed by odds ratio with 95% confidence interval. The genotype distributions and allele frequencies of the four SNPs in the HRH4 gene did not show obvious differences between the whole group of psoriasis patients and healthy controls. However, there were differences by trend in subgroup analysis: The mutant genotypes (A/G) of rs17203314 and (G/A) of rs615283 were more frequent in patients with severe psoriasis PASI≥30 (34.8% and 34.8%) when compared to the control groups (23.5% and 27.2%), respectively. The mutant G/A genotype of rs615283 was significantly more frequent in patients with moderate-to-severe psoriasis PASI≥10 when compared to mild psoriasis PASI<10 (33.3% vs 21.7%, p=0.022). For rs524149 and rs17797945 the wildtype CC genotype was more frequent by trend in moderately-to-severely affected patients with PASI≥10 (85.2% and 63.0%) when compared to the group with mild psoriasis PASI<10 (77.0% and 49.4%), respectively. Furthermore, a significant association of rs615283 with psoriasis palmoplantaris was detected. In conclusion our study suggests that genetic variations within the HRH4 gene might be associated with special clinical features of psoriasis. Further studies are needed in larger study populations to confirm the reported associations and investigate the functional relevance of the identified SNPs.

Population pharmacokinetic/pharmacodynamic modeling of histamine response measured by histamine iontophoresis laser Doppler

The epicutaneous histamine (EH) test is the current gold standard method for the clinical evaluation of allergic conditions. However, the EH method is limited in providing an objective and qualitative assessment of histamine pharmacodynamic response. The histamine iontophoresis with laser Doppler (HILD) monitoring method, an alternative method, allows a fixed dose of histamine to be delivered and provides an objective, continuous, and dynamic measurement of histamine epicutaneous response in children and adults. However, due to the high sampling frequency (up to 40 Hz), the output files are usually too cumbersome to be directly used for further analysis. In this study, we developed an averaging algorithm that efficiently reduces the HILD data in size. The reduced data was further analyzed and a population linked effect pharmacokinetic/pharmacodynamic (PK/PD) model was developed to describe the local histamine response. The model consisted of a one-compartment PK model and a direct-response fractional maximum effect (Emax) model. The parameter estimates were obtained as follows: absorption rate constant (ka), 0.094/min; absorption lag time (Tlag), 2.72 min; partitioning clearance from local depot to systemic circulation (CLpar), 0.0006 L/min; baseline effect (E0), 13.1 flux unit; Emax, 13.4; concentration at half maximum effect (EC50) 31.1 mg/L. Covariate analysis indicated that age and race had significant influence on Tlag and EC50, respectively.