Histamine-cytokine connection in immunity and hematopoiesis

H1 Antihistamines-Promising Candidates for Repurposing in the Context of the Development of New Therapeutic Approaches to Cancer Treatment

Despite significant progress in the field of clinical oncology in terms of diagnostic and treatment methods, the results of anticancer therapy are still not fully satisfactory, especially due to limited response and high toxicity. This has forced the need for further research to finding alternative ways to improve success rates in oncological treatment. A good solution to this problem in the context of rapidly obtaining an effective drug that works on multiple levels of cancer and is also safe is the global strategy of repurposing an existing drug. Research into other applications of an existing drug enables a precise assessment of its possible mechanisms of action and, consequently, the broadening of therapeutic indications. This strategy is also supported by the fact that most non-oncological drugs have pleiotropic effects, and most of the diseases for which they were originally intended are multifactorial, which in turn is a very desirable phenomenon due to the heterogeneous and multifaceted biology of cancer. In this review, we will mainly focus on the anticancer potential of H1 antihistamines, especially the new generation that were not originally intended for cancer therapy, to highlight the relevant signaling pathways and discuss the properties of these agents for their judicious use based on the characteristic features of cancer.

SYNLAC prime probiotics enhances growth performance, and resistance of white shrimp, Penaeus vannamei to Enterocytozoon hepatopenaei and Vibrio alginollyticus: Insights into immune and metabolic pathway modulations

This study explores the impact of SYNLAC Prime probiotics on the growth performance, health status, and metabolic profile of white shrimp, Penaeus vannamei. Shrimp fed with the experimental diets, including the control diet without probiotic supplementation, and the diets supplemented with SYNLAC Prime probiotics at concentrations of 105 CFU (g diet)-1 (P5) and 106 CFU (g diet)-1 (P6) for 56 days. Results indicated a significant enhancement in growth performance in probiotic-treated shrimp relative to the control group, attributed to structural improvements in the digestive tract, particularly the increased abundances of B cells in the hepatopancreas. The administration of dietary probiotics markedly reduced the severity of Enterocytozoon hepatopenaei (EHP) infection and decreased cumulative mortalities following Vibrio alginolyticus challenge. Shrimp in the P6 group exhibited significant elevations in phenoloxidase activity, respiratory burst, lysozyme activity and phagocytic activity compared to control group. Furthermore, there was an upregulation of several immune-related genes in hepatopancreas, including serine protease (SP), prophenoloxidase (proPO) I, proPO II, and penaeidin 3a. Additionally, the expression of β-1, 3-glucan binding protein and SP mRNA was significantly increased in hemocytes. Untargeted metabolomics analysis using LC-MS/MS revealed significant changes in the hepatopancreas metabolic profile, highlighting alterations in energy metabolisms pathways, such as citrate cycle and nicotinate and nicotinamide metabolism, as well as amino acid metabolisms pathways including arginine and proline metabolism, taurine and hypotaurine metabolism, and histidine metabolism. These findings underscore the potential of SYNLAC Prime probiotics in enhancing shrimp growth, immune function, and metabolic pathways, offering valuable insights for advancing health management strategies in shrimp aquaculture.

Therapeutic potential of histamine H4 receptor antagonist as a preventive treatment for diabetic retinopathy in mice

Diabetic retinopathy (DR) is a prevalent complication of diabetes, often resulting in vision loss and blindness. Existing treatments primarily aim to control blood sugar levels and inhibit angiogenesis. However, current therapies for DR, such as anti-VEGF and laser photocoagulation, are frequently invasive, and can cause adverse side effects. Consequently, there is a critical need for new preventive therapeutics to address DR more effectively. This study aimed to examine the therapeutic potential of a histamine H4 receptor (HRH4) antagonist as a preventive treatment for DR in mice. A mouse model of DR was established by intraperitoneally injecting 200 mg/kg of streptozotocin (STZ). Immune cell infiltration into the retina of mice with STZ-induced diabetes was measured using fluorescence-activated cell sorting (FACS) 12 weeks after STZ injection. The preventive effects of the HRH4 antagonist on inflammation and pathological retinal vessel leakage were determined in a mouse model of DR. Infiltration of HRH4-expressing macrophages increased in the retina of mice with STZ-induced DR. The HRH4 antagonist prevented macrophage infiltration and retinal vascular leakage to prevent STZ-induced DR in mice without causing any retinal toxicity. The infiltration of macrophages increased in the retina of mice with STZ-induced diabetes through HRH4, indicating that HRH4 is potentially a novel preventative therapeutic target in DR. These findings suggest that targeting HRH4 is a promising strategy for the prevention and treatment of DR.

The story of clobenpropit and CXCR4: can be an effective drug in cancer and autoimmune diseases?

Clobenpropit is a histamine H3 receptor antagonist and has developed as a potential therapeutic drug due to its ability to inhibit CXCR4, a chemokine receptor involved in autoimmune diseases and cancer pathogenesis. The CXCL12/CXCR4 axis involves several biological phenomena, including cell proliferation, migration, angiogenesis, inflammation, and metastasis. Accordingly, inhibiting CXCR4 can have promising clinical outcomes in patients with malignancy or autoimmune disorders. Based on available knowledge, Clobenpropit can effectively regulate the release of monocyte-derived inflammatory cytokine in autoimmune diseases such as juvenile idiopathic arthritis (JIA), presenting a potential targeted target with possible advantages over current therapeutic approaches. This review summarizes the intricate interplay between Clobenpropit and CXCR4 and the molecular mechanisms underlying their interactions, comprehensively analyzing their impact on immune regulation. Furthermore, we discuss preclinical and clinical investigations highlighting the probable efficacy of Clobenpropit for managing autoimmune diseases and cancer. Through this study, we aim to clarify the immunomodulatory role of Clobenpropit and its advantages and disadvantages as a novel therapeutic opportunity.

The role of histamine and its receptors in breast cancer: from pathology to therapeutic targets

Breast cancer is the most common malignancy in women, and despite the development of new treatment methods and the decreasing mortality rate in recent years, one of the clinical problems in breast cancer treatment is chronic inflammation in the tumor microenvironment. Histamine, an inflammatory mediator, is produced by tumor cells and can induce chronic inflammation and the growth of some tumors by recruiting inflammatory cells. It can also affect tumor physiopathology, antitumor treatment efficiency, and patient survival. Antihistamines, as histamine receptor antagonists, play a role in modulating the effects of these receptors in tumor cells and can affect some treatment methods for breast cancer therapy; in this review, we investigate the role of histamine, its receptors, and antihistamines in breast cancer pathology and treatment methods.

Peptide-Based Recognition Agents of Histamine: A Biopanning Approach with Enhanced Specificity

Histamine is a biogenic amine that poses a potential threat to public health due to its toxicological effects. In this study, we identified histamine-binding peptides by screening a random 12-mer peptide library, employing a novel biopanning approach that excluded histidine-binding sequences in the final round. This additional step enhanced the selectivity of the peptides and prevented interference from histidine during detection. The binding affinities of synthesized peptides to histamine were assessed using isothermal titration calorimetry (ITC). Among the identified peptides, HBF10 (SGFRDGIEDFLW) and HBF26 (IPLENQHKIYST) showed significant affinity to histamine, with Ka values of 2.56×104 (M-1) and 8.94×104 (M-1), respectively. Notably, the identified peptides did not demonstrate binding affinity towards histidine, despite its structural similarity to histamine. Subsequently, the surface plasmon resonance (SPR) sensor surface was prepared by immobilizing the peptide HBF26 to investigate the potential of the peptide as a recognition agent for histamine detection. The findings suggest that the identified peptides have an affinity to histamine specifically, showcasing their potential applications as diagnostic agents with specific targeting capabilities.

Chronic Visceral Pain: New Peripheral Mechanistic Insights and Resulting Treatments

Chronic visceral pain is one of the most common reasons for patients with gastrointestinal disorders, such as inflammatory bowel disease or disorders of brain-gut interaction, to seek medical attention. It represents a substantial burden to patients and is associated with anxiety, depression, reductions in quality of life, and impaired social functioning, as well as increased direct and indirect health care costs to society. Unfortunately, the diagnosis and treatment of chronic visceral pain is difficult, in part because our understanding of the underlying pathophysiologic basis is incomplete. In this review, we highlight recent advances in peripheral pain signaling and specific physiologic and pathophysiologic preclinical mechanisms that result in the sensitization of peripheral pain pathways. We focus on preclinical mechanisms that have been translated into treatment approaches and summarize the current evidence base for directing treatment toward these mechanisms of chronic visceral pain derived from clinical trials. The effective management of chronic visceral pain remains of critical importance for the quality of life of suffers. A deeper understanding of peripheral pain mechanisms is necessary and may provide the basis for novel therapeutic interventions.

Impact of autoimmune gastritis on chronic urticaria in paediatric patients - pathophysiological point of views

We would like to provide an updated comprehensive perspective and identify the components linked to chronic spontaneous urticaria (CSU) without specific triggers in autoimmune atrophic gastritis (AAG). AAG is an organ-specific autoimmune disease that affects the corpus-fundus gastric mucosa. Although we lack a unified explanation of the underlying pathways, when considering all paediatric patients reported in the literature, alterations result in gastric neuroendocrine enterochromaffin-like (ECL) cell proliferation and paracrine release of histamine. Several mechanisms have been proposed for the pathogenesis of CSU, with much evidence pointing towards AAG and ECL cell responses, which may be implicated as potential factors contributing to CSU. The excessive production/release of histamine into the bloodstream could cause or trigger exacerbations of CSU in AAG, independent of Helicobacter pylori; thus, the release of histamine from ECL cells may be the primary modulator.

CONCLUSION

Considering the understanding of these interactions, recognising the respective roles of AAG in the pathogenesis of CSU may strongly impact the diagnostic workup and management of unexplained/refractory CSU and may inform future research and interventions in the paediatric population.

WHAT IS KNOWN

• Autoimmune atrophic gastritis is a chronic immune-mediated inflammatory disease characterised by the destruction of the oxyntic mucosa in the gastric body and fundus, mucosal atrophy, and metaplastic changes. • Autoimmune atrophic gastritis in paediatric patients is important because of the poor outcome and risk of malignancy and possibly underestimated entities primarily reported in single-case reports.

WHAT IS NEW

• Upper gastrointestinal inflammatory disorders, independent of H. pylori, have been implicated as potential inducing factors in the development of chronic spontaneous urticaria. • If a paediatric patient presents with symptoms such as anaemia, reduced vitamin B12 levels, recurrent urticaria with no other detectable aetiology, positive anti-parietal cell antibodies, and elevated gastrin levels, autoimmune atrophic gastritis should be considered a possible cause of chronic urticaria.

Histamine deficiency inhibits lymphocyte infiltration in the submandibular gland of aged mice via increased anti-aging factor Klotho

OBJECTIVES

Histidine decarboxylase (HDC), a histamine synthase, is expressed in various tissues and is induced by proinflammatory cytokines such as TNFα. As they age, C57BL/6 mice show auto-antibody deposition and lymphocyte infiltration into various tissues, including salivary glands. However, the mechanism underlying cell infiltration and the change in HDC expression in salivary glands with aging remain unclear. Thus, we aimed to elucidate the relationship between histamine and inflammaging.

METHODS

We investigated the change in histology and HDC expression in the major salivary glands (parotid, submandibular, and sublingual) of 6-week- and 9-month-old wild-type mice. We also determined the histological changes, cytokine expression, and anti-aging factor Klotho in the salivary glands of 9-month-old wild-type and HDC-deficient (HDC-KO) mice.

RESULTS

Cell infiltration was observed in the submandibular gland of 9-month-old wild-type mice. Although most cells infiltrating the submandibular glands were CD3-positive and B220-positive lymphocytes, CD11c-positive and F4/80-positive monocyte lineages were also detected. HDC, TNFα, and IL-1β mRNA expression increased in the submandibular gland of 9-month-old wild-type mice. The expression of PPARγ, an anti-inflammatory protein, declined in 9-month-old wild-type mice, and Klotho expression increased in 9-month-old HDC-KO mice. Immunohistochemistry showed that Klotho-positive cells disappeared in the submandibular gland of 9-month-old wild-type mice, while Klotho was detected in all salivary glands in HDC-KO mice of the same age.

CONCLUSION

Our findings demonstrate the multifunctionality of histamine and can aid in the development of novel therapeutic methods for inflammatory diseases such as Sjogren's syndrome and age-related dysfunctions.

Inflammatory Bowel Disease: Crosstalk between Histamine, Immunity, and Disease

Inflammatory bowel disease (IBD) is increasingly recognized as a serious, worldwide public health concern. It is generally acknowledged that a variety of factors play a role in the pathogenesis of this group of chronic inflammatory diseases. The diversity of molecular actors involved in IBD does not allow us to fully assess the causal relationships existing in such interactions. Given the high immunomodulatory activity of histamine and the complex immune-mediated nature of inflammatory bowel disease, the role of histamine and its receptors in the gut may be significant. This paper has been prepared to provide a schematic of the most important and possible molecular signaling pathways related to histamine and its receptors and to assess their relevance for the development of therapeutic approaches.

IL-33 induces histidine decarboxylase, especially in c-kit+ cells and mast cells, and roles of histamine include negative regulation of IL-33-induced eosinophilia

OBJECTIVE AND METHODS

IL-33 is present in endothelial, epithelial, and fibroblast-like cells and released upon cell injury. IL-33 reportedly induces mast-cell degranulation and is involved in various diseases, including allergic diseases. So, IL-33-related diseases seem to overlap with histamine-related diseases. In addition to the release from mast cells, histamine is newly formed by the induction of histidine decarboxylase (HDC). Some inflammatory and/or hematopoietic cytokines (IL-1, IL-3, etc.) are known to induce HDC, and the histamine produced by HDC induction is released without storage. We examined the involvement of HDC and histamine in the effects of IL-33.

RESULTS

A single intraperitoneal injection of IL-33 into mice induced HDC directly and/or via other cytokines (including IL-5) within a few hours in various tissues, particularly strongly in hematopoietic organs. The major cells exhibiting HDC-induction were mast cells and c-kit⁺ cells in the bone marrow. HDC was also induced in non-mast cells in non-hematopoietic organs. HDC, histamine, and histamine H4 receptors (H4Rs) contributed to the suppression of IL-33-induced eosinophilia.

CONCLUSION

IL-33 directly and indirectly (via IL-5) induces HDC in various cells, particularly potently in c-kit⁺ cells and mature mast cells, and the newly formed histamine contributes to the negative regulation of IL-33-induced eosinophilia via H4Rs.

Histamine deficiency deteriorates LPS-induced periodontal diseases in a murine model via NLRP3/Caspase-1 pathway

Histamine is a versatile biogenic amine, generated by the unique enzyme histidine decarboxylase (Hdc). Accumulating evidence has proven that histamine plays important roles in numerous biological and pathophysiological processes. However, the role and mechanism of Hdc/Histamine signaling in periodontal diseases remain unclear. In our current study, the concentration of histamine increased in the serum, and Hdc gene expression was upregulated in the gingiva of WT mice with LPS-induced periodontal inflammation. With Hdc-GFP mice, we identified that Hdc/GFP in the periodontium was expressed in CD11b⁺ myeloid cells, rather than in tryptase-positive mast cells. Hdc-expressing CD11b⁺Gr-1⁺ neutrophils significantly increased in the peripheral blood of Hdc-GFP mice one day after LPS injection. Lack of histamine in Hdc^-/- mice not only promoted the activation and infiltration of more CD11b⁺ cells into the peripheral blood but also upregulated mRNA expression levels of IL-1β, IL-6, MCP-1and MMP9 in the gingiva compared to WT mice one day after LPS stimulation. 28 days after LPS treatment, we observed that Hdc^-/- mice exhibited more alveolar bone loss and more osteoclasts than WT mice, which was slightly ameliorated by the administration of exogenous histamine. In vivo and in vitro mechanistic studies revealed that the mRNA expression levels of proinflammatory cytokines and protein levels of NLRP3, Caspase-1, and cleaved-Caspase-1 were upregulated after blocking histamine receptor 1 and 2, especially histamine receptor 1. Taken together, CD11b⁺Gr-1⁺ neutrophils are the predominant Hdc-expressing sites in periodontal inflammation, and deficiency of endogenous histamine in Hdc^-/- mice exacerbates the destruction of the periodontium. Disruption of the histamine/H₁R/H₂R axis aggravates the inflammatory immune response via NLRP3/Casapse-1 pathway.

Mast cell activation mediates blood-brain barrier impairment and cognitive dysfunction in septic mice in a histamine-dependent pathway

Introduction

Sepsis-associated encephalopathy (SAE) is a diffuse cerebral dysfunction resulting from a systemic inflammatory response to infection; however, its pathophysiology remains unclear. Sepsis-induced neuroinflammation and blood-brain barrier (BBB) disruption are crucial factors in brain function disturbance in SAE. Mast cells (MCs) activation plays an important role in several neuroinflammation models; however, its role in SAE has not been comprehensively investigated.

Methods

We first established a SAE model by cecal ligation puncture (CLP) surgery and checked the activation of MCs. MCs activation was checked using immumohistochemical staining and Toluidine Blue staining. We administrated cromolyn (10mg/ml), a MC stabilizer, to rescue the septic mice. Brain cytokines levels were measured using biochemical assays. BBB disruption was assessed by measuring levels of key tight-junction (TJ) proteins. Cognitive function of mice was analyzed by Y maze and open field test. Transwell cultures of brain microvascular endothelial cells (BMVECs) co-cultured with MCs were used to assess the interaction of BMVECs and MCs.

Results

Results showed that MCs were overactivated in the hippocampus of CLP-induced SAE mice. Cromolyn intracerebroventricular (i.c.v) injection substantially inhibited the MCs activation and neuroinflammation responses, ameliorated BBB impairment, improved the survival rate and alleviated cognitive dysfunction in septic mice. In vitro experiments, we revealed that MCs activation increased the sensitivity of BMVECs against to lipopolysaccharide (LPS) challenge. Furthermore, we found that the histamine/histamine 1 receptor (H1R) mediated the interaction between MCs and BMVECs, and amplifies the LPS-induced inflammatory responses in BMVECs by modulating the TLR2/4-MAPK signaling pathway.

Conclusions

MCs activation could mediate BBB impairment and cognitive dysfunction in septic mice in a histamine-dependent pathway.

Specific histamine regulating activity of surface-modified yeast vacuoles by histamine- binding protein and its immune-enhancing effect

We aimed to develop a biocompatible material that could enhance weakened immunity and control histamine in vivo. Histamine‐binding protein (HBP) vacuoles have a mechanism of action that directly binds to the histamine molecule. It is designed to eliminate the side effects of antihistamine caused by binding to other receptors. HBP vacuoles were designed to produce a material that was biocompatible, and could enhance immunity. First, a recombinant vector was designed so that HBP was located on the vacuole surface, and expressed towards the cytoplasm. The vector was transformed into yeast, and protein expression was induced. Then, the vacuole was isolated by centrifugation to complete HBP vacuoles. Cytotoxicity test was conducted for application to RAW 264.7 cells. In addition, immune enhancement reaction and histamine inhibition were confirmed through phagocytosis assay and histamine ELISA. RAW 264.7 cells were pre‐treated with HBP vacuoles to confirm the immune enhancement of HBP vacuoles. As a result, it was confirmed that the immunostimulatory effect of the vacuole was increased in a concentration‐dependent manner. In addition, the reduction of histamine was confirmed by treating the HBP vacuoles. As a result, HBP vacuoles reduced the histamine secreted from RAW 264.7 cells by about 75%.

Role of Microbial Metabolites of Histidine in the Development of Colitis

SCOPE

Colitis is a chronic relapsing inflammatory disease of colon. Clinical studies show that meat-rich diet plays a critical role in the relapse of colitis. However, it is unclear whether the microbial metabolites of histidine, which is an amino acid widely found in meat, have an impact on the health of the intestine.

METHODS AND RESULTS

Six metabolites of histidine are given to IEC-6 cells. The cell activity measurement shows that imidazole propionate (IMP) is the most detrimental metabolite. Then, IMP is injected to mice by rectal administration, with blood and colon tissues collected for the measurement of colitis related parameters. The results show that treatment with IMP significantly increased NF-κB, iNOS, and IL-6, decreased number of goblet cell, and inhibited expressions of miR-146b. However, overexpression of miR-146b in mice rescues the decline of the physical condition. Additionally, Notch receptor 1 (Notch1) is identified as a target gene of miR-146b. Further analysis shows that miR-146b restored the abundance of goblet cells by regulating Notch1 signaling pathway.

CONCLUSION

IMP is able to induce intestinal inflammation, impairs the intestinal barrier, and affects the proliferation of goblet cells. The underlined mechanism may partially contribute to the dysregulation of miR-146b/Notch1 axis.

Recent Progress of Fluorescence Sensors for Histamine in Foods

Biological amines are organic nitrogen compounds that can be produced by the decomposition of spoiled food. As an important biological amine, histamine has played an important role in food safety. Many methods have been used to detect histamine in foods. Compared with traditional analysis methods, fluorescence sensors as an adaptable detection tool for histamine in foods have the advantages of low cost, convenience, less operation, high sensitivity, and good visibility. In terms of food safety, fluorescence sensors have shown great utilization potential. In this review, we will introduce the applications and development of fluorescence sensors in food safety based on various types of materials. The performance and effectiveness of the fluorescence sensors are discussed in detail regarding their structure, luminescence mechanism, and recognition mechanism. This review may contribute to the exploration of the application of fluorescence sensors in food-related work.

The Roles of Cardiovascular H2-Histamine Receptors Under Normal and Pathophysiological Conditions

This review addresses pharmacological, structural and functional relationships among H₂-histamine receptors and H₁-histamine receptors in the mammalian heart. The role of both receptors in the regulation of force and rhythm, including their electrophysiological effects on the mammalian heart, will then be discussed in context. The potential clinical role of cardiac H₂-histamine-receptors in cardiac diseases will be examined. The use of H₂-histamine receptor agonists to acutely increase the force of contraction will be discussed. Special attention will be paid to the potential role of cardiac H₂-histamine receptors in the genesis of cardiac arrhythmias. Moreover, novel findings on the putative role of H₂-histamine receptor antagonists in treating chronic heart failure in animal models and patients will be reviewed. Some limitations in our biochemical understanding of the cardiac role of H₂-histamine receptors will be discussed. Recommendations for further basic and translational research on cardiac H₂-histamine receptors will be offered. We will speculate whether new knowledge might lead to novel roles of H₂-histamine receptors in cardiac disease and whether cardiomyocyte specific H₂-histamine receptor agonists and antagonists should be developed.

Hymenoptera Venom Immunotherapy: Immune Mechanisms of Induced Protection and Tolerance

Hymenoptera venom allergy is one of the most severe allergic diseases, with a considerable prevalence of anaphylactic reaction, making it potentially lethal. In this review, we provide an overview of the current knowledge and recent findings in understanding induced immune mechanisms during different phases of venom immunotherapy. We focus on protection mechanisms that occur early, during the build-up phase, and on the immune tolerance, which occurs later, during and after Hymenoptera venom immunotherapy. The short-term protection seems to be established by the early desensitization of mast cells and basophils, which plays a crucial role in preventing anaphylaxis during the build-up phase of treatment. The early generation of blocking IgG antibodies seems to be one of the main reasons for the lower activation of effector cells. Long-term tolerance is reached after at least three years of venom immunotherapy. A decrease in basophil responsiveness correlates with tolerated sting challenge. Furthermore, the persistent decline in IgE levels and, by monitoring the cytokine profiles, a shift from a Th2 to Th1 immune response, can be observed. In addition, the generation of regulatory T and B cells has proven to be essential for inducing allergen tolerance. Most studies on the mechanisms and effectiveness data have been obtained during venom immunotherapy (VIT). Despite the high success rate of VIT, allergen tolerance may not persist for a prolonged time. There is not much known about immune mechanisms that assure long-term tolerance post-therapy.

Metabolic Profile Reveals the Immunosuppressive Mechanisms of Methionyl-Methionine in Lipopolysaccharide-Induced Inflammation in Bovine Mammary Epithelial Cell

Our previous transcriptomic study found that methionyl-methionine (Met-Met) exerts an anti-inflammatory effect in the bovine mammary epithelial cell (MAC-T) at a molecular level. However, evidence of whether the metabolic production of Met-Met confers protection was scarce. To investigate the inflammatory response and metabolite changes of Met-Met in lipopolysaccharide (LPS)-induced inflammation of MAC-T, mass spectrometry-based metabolomics and qPCR were conducted. The increased levels of IL-8, TNF-α, AP-1, and MCP-1 were reduced by pretreating with 2 mM Met-Met after LPS exposure. Metabolomics profiling analysis demonstrated that LPS induced significant alteration of metabolites, including decreased tryptophan, phenylalanine, and histidine levels and increased palmitic acid and stearic acid levels as well as purine metabolism disorder, whereas Met-Met reversed these changes significantly. Pathways analysis revealed that overlapping metabolites were mainly enriched in the cysteine and methionine metabolism, fatty acids biosynthesis, and purines degradation. Correlation networks showed that the metabolic profile was significantly altered under the conditions of inflammation and Met-Met treatment. Collectively, Met-Met might relieve MAC-T cell inflammation via hydrolysate methionine, which further changes the processes of amino acid, purine, and fatty acid metabolism.

In vitro effects of histamine receptor 1 antagonists on proliferation and histamine release in canine neoplastic mast cells

Canine mastocytomas (MCTs) are characterized by rapid proliferation of neoplastic mast cells (MCs) and clinical signs caused by MC-derived mediators. In dogs suffering from MCT, histamine receptor 1 (HR1) antagonists are frequently used to control mediator-related clinical symptoms. Previous studies have shown that the HR1 antagonists loratadine and terfenadine exert some growth-inhibitory effects on neoplastic MCs. We examined whether other HR1 antagonists used in clinical practice (desloratadine, rupatadine, cyproheptadine, dimetindene, diphenhydramine) affect proliferation and survival of neoplastic MCs. Furthermore, we analysed whether these HR1 antagonists counteract IgE-dependent histamine release from a MC line harbouring a functional IgE-receptor. HR1 antagonists were applied on two canine MC lines, C2 and NI-1, and on primary MCs obtained from three MCT samples. The HR1 antagonists desloratadine, rupatadine and cyproheptadine were found to be more potent in decreasing proliferation of C2 and NI-1 cells when compared with dimetindene and diphenhydramine. Similar effects were seen in primary neoplastic MCs, except for diphenhydramine, which exerted more potent growth-inhibitory effects than the other HR1 antagonists. Drug-induced growth-inhibition in C2 and NI-1 cells was accompanied by apoptosis. Loratadine, desloratadine and rupatadine also suppressed IgE-dependent histamine release in NI-1 cells. However, drug concentrations required to elicit substantial effects on growth or histamine release were relatively high (>10 µM). Therefore, it remains unknown whether these drugs or similar, more potent, HR1-targeting drugs can suppress growth or activation of canine neoplastic MCs in vivo.

Histamine receptors and cancer pharmacology: an update

In the present review, we will discuss the recent advances in the understanding of the role of histamine and histamine receptors in cancer biology. The controversial role of the histaminergic system in different neoplasias including gastric, colorectal, oesophageal, oral, pancreatic, liver, lung, skin, blood and breast cancers will be reviewed. The expression of histamine receptor subtypes, with special emphasis on the histamine H4 receptor, in different cell lines and human tumours, the signal transduction pathways and the associated biological responses as well as the in vivo treatment of experimental tumours with pharmacological ligands will be described. The presented evidence demonstrates that histamine regulates cancer-associated biological processes during cancer development in multiple cell types, including neoplastic cells and cells in the tumour micro-environment. The outcome will depend on tumour cell type, the level of expression of histamine receptors, signal transduction associated with these receptors, tumour micro-environment and histamine metabolism, reinforcing the complexity of cancer disease. Findings show the pivotal role of H4 receptors in the development and progression of many types of cancers, and considering its immunomodulatory properties, the H4 receptor appears to be the most promising molecular therapeutic target for cancer treatment within the histamine receptor family. Furthermore, the H4 receptor is differentially expressed in tumours compared with normal tissues, and in most cancer types in which data are available, H4 receptor expression is associated with clinicopathological characteristics, suggesting that H4 receptors might represent a novel cancer biomarker. LINKED ARTICLES: This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.

Interleukin-1 and histamine are essential for inducing nickel allergy in mice

BACKGROUND

We previously reported that (a) lipopolysaccharide (LPS) is a potent adjuvant for inducing Nickel (Ni) allergy in mice at both the sensitization and elicitation steps, (b) LPS induces Interleukin-1 (IL-1) and histidine decarboxylase (HDC, the histamine-forming enzyme), and IL-1 induces HDC, (c) Ni allergy is induced in mast cell-deficient, but not IL-1-deficient (IL-1-KO) or HDC-KO mice.

OBJECTIVE

To examine the roles of IL-1 and HDC (or histamine) and their interrelationship during the establishment of Ni allergy.

METHODS

Ni (NiCl₂ ) 1 mmol/L containing IL-1β and/or histamine was injected intraperitoneally (sensitization step). Ten days later, test substance(s) were intradermally injected into ear pinnas (elicitation step), and ear swelling was measured.

RESULTS

In wild-type mice, Ni + LPS or Ni + IL-1β injection at sensitization step followed by Ni alone at elicitation step induced Ni allergy. In IL-1-KO, injection of Ni + IL-1β (but not Ni + histamine) was required at both sensitization and elicitation steps to induce Ni allergy. In HDC-KO, Ni + IL-1β + histamine at sensitization step followed by Ni + histamine at elicitation step induced Ni allergy. In histamine H1 receptor-deficient mice, IL-1β induced HDC, but was ineffective as an adjuvant for inducing Ni allergy. In wild-type mice, injection into ear pinnas of Ni 10 mmol/L alone or Ni 1 mmol/L + LPS induced IL-1β, HDC and a prolonged swelling of ear pinnas. In non-sensitized mice, injection of IL-1β by itself into ear pinnas in IL-1-KO mice induced prolonged ear swelling. Ni augmented IL-1 production (both IL-1α and IL-1β) and HDC induction in wild-type mice sensitized to Ni.

CONCLUSIONS

In mice: (a) for inducing Ni allergy, IL-1 is essential at both the sensitization and elicitation steps, and HDC induction is involved in the effect of IL-1, (b) stimulation of H1 receptor is also essential for inducing Ni allergy at both sensitization and elicitation steps, and (c) the 'sensitization to Ni' state may be a state where tissues are primed for augmented production of IL-1α and/or IL-1β in response to Ni. (within 300 words, now 300).

Urinary metabolomic profiling for noninvasive diagnosis of acute T cell-mediated rejection after kidney transplantation

To improve early renal allograft function, it is important to develop a noninvasive diagnostic method for acute T cell-mediated rejection (TCMR). This study aims to explore potential noninvasive urinary biomarkers to screen for acute TCMR in kidney transplant recipients (KTRs) using untargeted metabolomic profiling. Urinary metabolites, collected from KTRs with stable graft function (STA) or acute TCMR episodes, were analyzed using liquid chromatography-mass spectrometry (LC-MS). Multivariate statistical analyses were performed to discriminate differences in urinary metabolites between the two groups. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of potential urinary biomarkers. Statistical analysis revealed the differences in urinary metabolites between the two groups and indicated several statistically significant metabolic features suitable for potential biomarkers. By comparing the retention times and mass fragmentation patterns of the chemicals in metabolite databases, samples, and standards, six of these features were clearly identified. ROC curve analysis showed the best performance of the training set (area under the curve value, 0.926; sensitivity, 90.0%; specificity, 84.6%) using a panel of five potential biomarkers: guanidoacetic acid, methylimidazoleacetic acid, dopamine, 4-guanidinobutyric acid, and L-tryptophan. The diagnostic accuracy of this model was 62.5% for an independent test dataset. LC-MS-based untargeted metabolomic profiling is a promising method to discriminate between acute TCMR and STA groups. Our model, based on a panel of five potential biomarkers, needs to be further validated in larger scale studies.

Current Trends in Detection of Histamine in Food and Beverages

Histamine is a heterocyclic amine formed by decarboxylation of the amino acid l-histidine. It is involved in the local regulation of physiological processes but also can occur exogenously in the food supply. Histamine is toxic at high intakes; therefore, determination of the histamine level in food is an important aspect of food safety. This article will review the current understanding of physiological functions of endogenous and ingested histamine with a particular focus placed on existing and emerging technologies for histamine quantification in food. Methods reported in this article are sequentially arranged and provide a brief overview of analytical methods reported, including those based on nanotechnologies.

Distinct roles of histamine H1- and H2-receptor signaling pathways in inflammation-associated colonic tumorigenesis

Inflammatory bowel disease (IBD) is a well-known risk factor for the development of colorectal cancer. Prior studies have demonstrated that microbial histamine can ameliorate intestinal inflammation in mice. We tested the hypothesis whether microbe-derived luminal histamine suppresses inflammation-associated colon cancer in Apc^min/+ mice. Mice were colonized with the human-derived Lactobacillus reuteri. Chronic inflammation was induced by repeated cycles of low-dose dextran sulfate sodium (DSS). Mice that were given histamine-producing L. reuteri via oral gavage developed fewer colonic tumors, despite the presence of a complex mouse gut microbiome. We further demonstrated that administration of a histamine H1-receptor (H1R) antagonist suppressed tumorigenesis, while administration of histamine H2-receptor (H2R) antagonist significantly increased both tumor number and size. The bimodal functions of histamine include protumorigenic effects through H1R and antitumorigenic effects via H2R, and these results were supported by gene expression profiling studies on tumor specimens of patients with colorectal cancer. Greater ratios of gene expression of H2R ( HRH2) vs. H1R ( HRH1) were correlated with improved overall survival outcomes in patients with colorectal cancer. Additionally, activation of H2R suppressed phosphorylation of mitogen-activated protein kinases (MAPKs) and inhibited chemokine gene expression induced by H1R activation in colorectal cancer cells. Moreover, the combination of a H1R antagonist and a H2R agonist yielded potent suppression of lipopolysaccharide-induced MAPK signaling in macrophages. Given the impact on intestinal epithelial and immune cells, simultaneous modulation of H1R and H2R signaling pathways may be a promising therapeutic target for the prevention and treatment of inflammation-associated colorectal cancer. NEW & NOTEWORTHY Histamine-producing Lactobacillus reuteri can suppress development of inflammation-associated colon cancer in an established mouse model. The net effects of histamine may depend on the relative activity of H1R and H2R signaling pathways in the intestinal mucosa. Our findings suggest that treatment with H1R or H2R antagonists could yield opposite effects. However, by harnessing the ability to block H1R signaling while stimulating H2R signaling, novel strategies for suppression of intestinal inflammation and colorectal neoplasia could be developed.

l-glutamine in vitro supplementation enhances Nile tilapia Oreochromis niloticus (Linnaeus, 1758) leukocyte function

Under appropriate conditions, glutamine (Gln) is an essential nutrient for immunological responses, acting as a metabolic substrate for proliferation of enterocytes and lymphocytes, and having positive effects on the function of stimulated immune cells. Thus, specific components of both innate and adaptive immune systems of Nile tilapia were evaluated after supplementing Gln to cell culture media. Primary cell cultures of kidney leukocytes were used for respiratory burst and phagocytic activity assessment. The ability of macrophages to kill Streptococcus iniae also was evaluated. Additionally, a proliferation assay was conducted with peripheral blood lymphocytes (PBL) exposed to non-specific mitogens. Results showed that macrophage phagocytosis, anion superoxide production, and bactericidal capacity were significantly (P < 0.05) enhanced by Gln supplementation to the culture media. The proliferation of lymphocytes upon mitogenic exposure also was significantly (P < 0.05) enhanced by Gln supplementation to the media. Our results suggest that in vitro, different levels of Gln were necessary for optimal immunological responses of leukocytes and lymphocytes. As such, Gln supplementation was able to enhance and modulate both innate and adaptive responses of Nile tilapia leukocytes, highlighting its potential application as an immunonutrient.

Immunomodulatory effects of phytogenics in chickens and pigs - A review

Environmental stressors like pathogens and toxins may depress the animal immune system through invasion of the gastrointestinal tract (GIT) tract, where they may impair performance and production, as well as lead to increased mortality rates. Therefore, protection of the GIT tract and improving animal health are top priorities in animal production. Being natural-sourced materials, phytochemicals are potential feed additives possessing multiple functions, including: anti-inflammatory, anti-fungal, anti-viral and antioxidative properties. This paper focuses on immunity-related physiological parameters regulated by phytochemicals, such as carvacrol, cinnamaldehyde, curcumin, and thymol; many studies have proven that these phytochemicals can improve animal performance and production. On the molecular level, the impact of inflammatory gene expression on underlying mechanisms was also examined, as were the effects of environmental stimuli and phytochemicals in initiating nuclear factor kappa B and mitogen-activated protein kinases signaling pathways and improving health conditions.

Proteomic Response of Human Umbilical Vein Endothelial Cells to Histamine Stimulation

The histamine receptors (HRs) represent a subclass of G protein-coupled receptors (GPCRs) and comprise four subtypes. Due to their numerous physiological and pathological effects, HRs are popular drug targets for the treatment of allergic reactions or the regulation of gastric acid secretion. Hence, an understanding of the functional selectivity of HR ligands has gained importance. These ligands can bind to specific GPCRs and selectively activate defined pathways. Supporting the activation of a therapeutically necessary pathway without the activation of other signaling cascades can result in drugs with more specific activity and fewer side effects. To evaluate the cellular consequences resulting from receptor binding, comprehensive analyses of cellular protein alterations upon incubation with ligands are required. For this purpose, endothelial cells are treated with histamine, as the endogenous ligand of HRs, to obtain a global overview of its cellular effects. Quantitative proteomics and pathway analyses of histamine-treated and untreated cells reveal enrichment of the nuclear factor-κB and tumor necrosis factor signaling pathways, cytokine-cytokine receptor interactions, complement and coagulation cascades, and acute inflammatory processes upon histamine treatment. This strategy offers the opportunity to monitor HR-mediated signaling in a multidimensional manner.

Targeting Histamine Receptors in Irritable Bowel Syndrome: A Critical Appraisal

Irritable bowel syndrome is a group of functional gastrointestinal disorders with not yet fully clarified etiology. Recent evidence suggesting that mast cells may play a central role in the pathogenesis of irritable bowel syndrome paves the way for agents targeting histamine receptors as a potential therapeutic option in clinical treatment. In this review, the role of histamine and histamine receptors is debated. Moreover, the clinical evidence of anti-histamine therapeutics in irritable bowel syndrome is discussed.

Histamine H4 receptor signalling in tongue cancer and its potential role in oral carcinogenesis - a short report

PURPOSE

Recent reports indicate that histamine and its novel, high-affinity histamine H₄ receptor (H₄R) play a role in carcinogenesis, and thus H₄R signalling has become a focus of increasing interest in the pathogenesis of many cancers. The roles of H₄R in oral epithelial dysplasia (OED) and oral tongue squamous cell carcinoma (OTSCC) are unknown. The purpose of this study was to assess H₄R expression in OTSCC patients and in OTSCC-derived cell lines.

METHODS

Biopsies taken from OED, OTSCC and healthy oral mucosa were studied by immunostaining. Primary human oral keratinocytes (HOKs) and two OTSCC-derived cell lines (HSC-3 and SCC-25) were used for the in vitro studies. Quantitative real-time PCR was used to measure oncogene expression in the stimulated HOKs.

RESULTS

We found that H₄R-immunoreactivity was significantly reduced in the OED and OTSCC samples, especially in the samples with higher histopathological grades and noticeably increased mast cell counts. The presence of H₄R in HSC-3 cells had clearly waned, in contrast to the HOKs. Gene expression data indicated that histamine-relevant inflammatory and environmental elements may participate in the regulation of oncogenes.

CONCLUSIONS

Our results suggest an association between H₄R and oral carcinogenesis. Furthermore, our findings raise a potential implication of histamine-mediated factors in the regulation of oncogenes, possibly via mast cells, as crucial components of the tumor microenvironment. The identification of new elements that govern oral cancer development is highly relevant for the development of novel therapeutic approaches in OTSCC.

Preliminary study of histamine H4 receptor expressed on human CD4+ T cells and its immunomodulatory potency in the IL-17 pathway of psoriasis

BACKGROUND

Previous studies have shown the expression of histamine H₄ receptor (H4R) on CD4⁺ T cells, especially human CD4⁺ T_h2-polarized T cells.

OBJECTIVE

This study aimed to investigate the role of H4R on these effector T cells in psoriasis.

METHODS

We enrolled three patients each with active psoriasis, inactive psoriasis, scalp seborrheic dermatitis, and three normal controls, and compared the basal expression of H4R mRNA in their peripheral blood CD4⁺ T cells. Then, we identified H4R expression in dermal CD4⁺ T cells. Furthermore, we investigated H4R expression after stimulating separated peripheral blood CD4⁺ T cells with several inflammatory cytokines.

RESULTS

The results showed higher H4R expression in the active psoriasis group compared to the inactive psoriasis group. It was interesting that interleukin (IL)-23, which is a representative cytokine contributing to T_h17 cell differentiation, stimulated H4R expression significantly. After adding a selective H4R antagonist (JNJ-7777120) while the CD4⁺ T cells were polarized into T_h17 cells, we observed a tendency toward suppressed IL-17 secretion.

CONCLUSIONS

Histamine stimulation influences the IL-17 pathway in psoriasis via the fourth histamine receptor subtype, H4R, on CD4⁺ T cells. The immunomodulatory roles of H4R suggest its potency as a new therapeutic target for obstinate psoriasis.

Histamine and Histamine H4 Receptor Promotes Osteoclastogenesis in Rheumatoid Arthritis

Histamine H4 receptor (H4R) has immune-modulatory and chemotaxic effects in various immune cells. This study aimed to determine the osteoclastogenic role of H4R in rheumatoid arthritis (RA). The concentration of histamine in synovial fluid (SF) and sera in patients with RA was measured using ELISA. After RA SF and peripheral blood (PB) CD14+ monocytes were treated with histamine, IL-17, IL-21 and IL-22, and a H4R antagonist (JNJ7777120), the gene expression H4R and RANKL was determined by real-time PCR. Osteoclastogenesis was assessed by counting TRAP–positive multinucleated cells in PB CD14+ monocytes cultured with histamine, Th17 cytokines and JNJ7777120. SF and serum concentration of histamine was higher in RA, compared with osteoarthritis and healthy controls. The expression of H4R was increased in PB monocytes in RA patients. Histamine, IL-6, IL-17, IL-21 and IL-22 induced the expression of H4R in monocytes. Histamine, IL-17, and IL-22 stimulated RANKL expression in RA monocytes and JNJ7777120 reduced the RANKL expression. Histamine and Th17 cytokines induced the osteoclast differentiation from monocytes and JNJ7777120 decreased the osteoclastogenesis. H4R mediates RANKL expression and osteoclast differentiation induced by histamine and Th17 cytokines. The blockage of H4R could be a new therapeutic modality for prevention of bone destruction in RA.

Histamine Amplifies Immune Response of Gingival Fibroblasts

Histamine is an important mediator in immune responses, but it is unclear whether periodontal tissues express histamine receptors and are able to respond to histamine. We hypothesized that histamine, inflammatory cytokines, and bacterial components released in inflamed periodontal tissues may be synergistically involved in periodontitis. The present study showed that human gingival fibroblasts mainly express histamine receptor H1R, and responded to histamine to produce interleukin (IL)-8. Stimulation of gingival fibroblasts with tumor necrosis factor-α, IL-1α, and lipopolysaccharide markedly induced IL-8 production, and the IL-8 production was synergistically augmented in the presence of or pre-treatment with histamine. Selective inhibitors of mitogen-activated protein kinases (MAPKs), nuclear factor (NF)-κB, and phospholipase C (PLC) significantly inhibited the synergistic effect. These results indicate that histamine induces IL-8 production from gingival fibroblasts through H1R, and synergistically augments the inflammatory stimuli by amplification of the MAPK and NF-κB through H1R-linked PLC. Abbreviations used: HDC, histidine decarboxylase; LPS, lipopolysaccharide; IL, interleukin; TNF, tumor necrosis factor; HR, histamine receptor; PLC, phospholipase C; MAPK, mitogen-activated protein kinase; NF, nuclear factor; ERK, extracellular signal-related kinase; JNK, c-Jun N-terminal kinase; R, receptor; TLR, Toll-like receptor; α-MEM, alpha-minimum essential medium; FCS, fetal calf serum; RT-PCR, reverse-transcriptase polymerase chain-reaction; ELISA, enzyme-linked immunosorbent assay; SD, standard deviation; LDH, lactate dehydrogenase.

Critical in vivo roles of histamine and histamine receptor signaling in animal models of metabolic syndrome

Histamine, a classic low-molecular-weight amine, is synthesized from L-histidine by histidine decarboxylase (HDC), and histamine-specific receptors (HRs) are essential for its actions. Our serial in vivo studies have uniquely reported that expression of histamine/HRs is variably identified in atherosclerotic lesions, and that HDC-gene knockout mice without histamine/HRs signaling show a marked reduction of atherosclerotic progression. These data have convinced us that histamine plays a pivotal role in the pathogenesis of atherosclerosis. Among four subclasses of HRs, the expression profile of the main receptors (H1/2R) has been shown to be switched from H2R to H1R during monocyte to macrophage differentiation, and H1R is also predominant in smooth muscle and endothelial cells of atheromatous plaque. Using various animal models of H1/2R-gene knockout mice, H1R and H2R were found to reciprocally but critically regulate not only hypercholesterolemia-induced atherosclerosis and injury-induced arteriosclerosis, but also hyperlipidemia-induced nonalcoholic fatty liver disease (NAFLD). Metabolic syndrome manifests obesity, dyslipidemia, insulin resistance, atherosclerosis, and/or NAFLD, i.e. the dysregulation of lipid/bile acid/glucose metabolism. Therefore, although its etiology is complicated and multifactorial, histamine/HRs signaling has a close relationship with the development of metabolic syndrome. We herein review diverse, key in vivo roles of histamine/HR signaling in the pathogenesis of metabolic syndrome.

Mast cell histamine-mediated transient inflammation following exposure to nickel promotes nickel allergy in mice

We previously reported that allergic responses to nickel (Ni) were minimal in mice deficient in the histamine-forming enzyme histidine decarboxylase (HDC-KO), suggesting an involvement of histamine in allergic responses to Ni. However, it remains unclear how histamine is involved in the process of Ni allergy. Here, we examined the role of histamine in Ni allergy using a murine model previously established by us. Mice were sensitized to Ni by intraperitoneal injection of a NiCl2 -lipopolysaccharide (LPS) mixture. Ten days later, allergic inflammation was elicited by challenging ear-pinnas intradermally with NiCl2 . Then, ear-swelling was measured. Pyrilamine (histamine H1-receptor antagonist) or cromoglicate (mast cell stabilizer) was intravenously injected 1 h before the sensitization or the challenge. In cell-transfer experiments, spleen cells from Ni-sensitized donor mice were intravenously transferred into non-sensitized recipient mice. In both sensitized and non-sensitized mice, 1 mm or more NiCl2 (injected into ear-pinnas) induced transient non-allergic inflammation (Ni-TI) with accompanying mast cell degranulation. LPS did not affect the magnitude of this Ni-TI. Pyrilamine and cromoglicate reduced either the Ni-TI or the ensuing allergic inflammation when administered before Ni-TI (at either the sensitization or elicitation step), but not if administered when the Ni-TI had subsided. Experiments on HDC-KO and H1-receptor-KO mice, and also cell-transfer experiments using these mice, demonstrated histamine's involvement in both the sensitization and elicitation steps. These results suggest that mast cell histamine-mediated Ni-TI promotes subsequent allergic inflammatory responses to Ni, raising the possibility that control of Ni-TI by drugs may be effective at preventing or reducing Ni allergy.

Mast cells and histamine alter intestinal permeability during malaria parasite infection

Co-infections with malaria and non-typhoidal Salmonella serotypes (NTS) can present as life-threatening bacteremia, in contrast to self-resolving NTS diarrhea in healthy individuals. In previous work with our mouse model of malaria/NTS co-infection, we showed increased gut mastocytosis and increased ileal and plasma histamine levels that were temporally associated with increased gut permeability and bacterial translocation. Here, we report that gut mastocytosis and elevated plasma histamine are also associated with malaria in an animal model of falciparum malaria, suggesting a broader host distribution of this biology. In support of mast cell function in this phenotype, malaria/NTS co-infection in mast cell-deficient mice was associated with a reduction in gut permeability and bacteremia. Further, antihistamine treatment reduced bacterial translocation and gut permeability in mice with malaria, suggesting a contribution of mast cell-derived histamine to GI pathology and enhanced risk of bacteremia during malaria/NTS co-infection.

Interactions between histamine H1 receptor and its antagonists by using cell membrane chromatography method

Objectives

A high histamine H1 receptor (H1R) expression cell membrane chromatography (CMC) method was developed to investigate the affinity of ligands for H1R.

Methods

The affinity of ligands for H1R was evaluated by frontal analysis. Competition studies and molecular docking study were utilized to study the interactions that occurred at specific binding sites on H1R.

Key findings

The KD values measured by frontal analysis were (8.72 ± 0.21) × 10−7 M for azelastine, (9.12 ± 0.26) × 10−7 M for cyproheptadine, (9.90 ± 0.18) × 10−7 M for doxepin, (1.42 ± 0.13) × 10−6 M for astemizole, (2.25 ± 0.36) × 10−6 M for chlorpheniramine and (3.10 ± 0.27) × 10−6 M for diphenhydramine. The results had a positive correlation with those from radioligand binding assay. The ability of displacement order measured on the binding sites occupied by doxepin was doxepin (KD, (2.95 ± 0.21) × 10−8 M) &gt; astemizole (KD, (5.03 ± 0.18) × 10−7 M) &gt; chlorpheniramine (KD, (1.27 ± 0.16) × 10−6 M) &gt; cyproheptadine (KD, (1.61 ± 0.27) × 10−6 M), whose order met with the scores by molecular docking study.

Conclusions

The studies showed CMC could be applied to investigate drug–receptor interactions.

Stimulatory effects of histamine on migration of nasal fibroblasts

BACKGROUND

Fibroblast migration is crucial for normal wound repair after sinonasal surgery. Histamine is known to be involved in wound healing by its effects on cell proliferation and migration. This study aimed to determine whether histamine affects the migration of nasal fibroblasts and to investigate the mechanism of action of histamine on nasal fibroblasts.

METHODS

Primary cultures of nasal fibroblasts were established from inferior turbinate samples. Fibroblast migration was evaluated with scratch assays. Cells were treated with histamine and/or histamine receptor-selective antagonists. U-73122 and pertussis toxin, which are selective inhibitors of the lower signaling pathway of H1R and H4R, were used to confirm the modulation of nasal fibroblast migration by histamine. Fibroblast cytoskeletal structures were visualized with immunocytochemistry.

RESULTS

Histamine significantly stimulated the migration of nasal fibroblasts. Antagonists selective for HR1 and HR4 significantly reduced nasal fibroblast migration. In immunocytochemical staining, histamine treatment increased membrane ruffling and pyrilamine, diphenhydramine, fexofenadine, and JNJ7777120 decreased histamine-induced membrane ruffling. U-73122 and pertussis toxin also decreased histamine-induced migration of fibroblasts. Histamine maintains its stimulatory effects on fibroblast migration in the presence of mitomycin C, which blocks proliferation of cells.

CONCLUSION

We showed that histamine stimulates fibroblast migration in nasal fibroblasts. This effect appeared to be mediated by HR1 and HR4. However, because fibroblast migration also can be involved in scaring and fibrosis, more research is necessary to determine the effects of antihistamine on wound healing after sinus surgery.

Histamine deficiency promotes accumulation of immunosuppressive immature myeloid cells and growth of murine gliomas

To elucidate mechanisms underlying epidemiological findings of decreased risk of glioma development in patients with allergies and asthma, gliomas were induced in mice deficient for histidine decarboxylase (HDC), the enzyme responsible for histamine production. These mice exhibited shortened survival and enhanced tumor growth compared to wild-type (WT) mice. Previous studies have shown a pivotal role of HDC in maturation of bone marrow (BM)-derived myeloid cells. In our glioma models, brain-infiltrating leukocytes (BIL) demonstrated an increased frequency of CD11b⁺Gr1⁺ immature myeloid cells (IMC; both CD11b⁺Ly6G⁺ and CD11b⁺Ly6C⁺ subpopulations) as well as diminished CD8⁺ T cell infiltration and their effector functions in HDC^-/- mice compared with WT mice. Furthermore, HDC^-/- IMC demonstrated a more profound immune suppression of CD8⁺ T cell proliferation and functions associated with increased prostaglandin E2 (PGE2) expression levels. Celecoxib, a cyclooxygenase-2 inhibitor, which is vital for PGE2 production, abrogated suppressive capabilities of HDC^-/- IMC. In addition, glioma-bearing HDC-eGFP mice, in which HDC promoter drives green fluorescence protein (GFP) expression, exhibited decreased HDC promoter activities in CD11b⁺Gr1⁺ cells in the BM, spleen, and intracranial tumor site compared with non-tumor bearing HDC-eGFP mice. Additionally, in vitro culture with glioma supernatants decreased GFP expression in CD11b⁺Gr1⁺, CD11b⁺Ly6G⁺, and CD11b⁺Ly6C⁺ IMC. HDC expression levels inversely correlated with suppressive functions of CD11b⁺Gr1⁺ IMC, as GFP^-CD11b⁺Gr1⁺ more profoundly inhibited CD8⁺ T cell proliferation compared with CD11b⁺Gr1⁺GFP⁺ cells. Taken together, these data show a significant role of HDC in the glioma microenvironment via maturation of myeloid cells and resulting activation of CD8⁺ T cells.

The role of histamine H1 and H4 receptors in atopic dermatitis: from basic research to clinical study

Histamine plays important roles in inflammation and nervous irritability in allergic disorders, including atopic dermatitis (AD). It has been shown to regulate the expression of pruritic factors, such as nerve growth factor and semaphorin 3A, in skin keratinocytes via histamine H1 receptor (H1R). Furthermore, H1R antagonist reduced the level of IL-31, a cytokine involving the skin barrier and pruritus, in chronic dermatitis lesions in NC/Nga mice and patients with AD. Histamine plays roles in the induction of allergic inflammation by activating eosinophils, mast cells, basophils, and Th2 cells via histamine H4 receptor (H4R). H4R, in addition to H1R, is expressed on sensory neurons, and a decrease in scratching behaviors was observed in H4R-deficient mice and mice treated with a H4R antagonist. We found that the combined administration of H1R and H4R antagonists inhibited the itch response and chronic allergic inflammation, and had a pharmacological effect similar to that of prednisolone. Although the oral administration of H1R antagonists is widely used to treat AD, it is not very effective. In contrast, JNJ39758979, a novel H4R antagonist, had marked effects against pruritus in Japanese patients with AD in a phase II clinical trial. Next generation antihistaminic agents possessing H1R and H4R antagonistic actions may be a potent therapeutic drug for AD.

H2 Receptor-Mediated Relaxation of Circular Smooth Muscle in Human Gastric Corpus: the Role of Nitric Oxide (NO)

This study was designed to examine the effects of histamine on gastric motility and its specific receptor in the circular smooth muscle of the human gastric corpus. Histamine mainly produced tonic relaxation in a concentration-dependent and reversible manner, although histamine enhanced contractility in a minor portion of tissues tested. Histamine-induced tonic relaxation was nerve-insensitive because pretreatment with nerve blockers cocktail (NBC) did not inhibit relaxation. Additionally, K⁺ channel blockers, such as tetraethylammonium (TEA), apamin (APA), and glibenclamide (Glib), had no effect. However, N^G-nitro-L-arginine methyl ester (L-NAME) and 1H-(1,2,4)oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), did inhibit histamine-induced tonic relaxation. In particular, histamine-induced tonic relaxation was converted to tonic contraction by pretreatment with L-NAME. Ranitidine, the H₂ receptor blocker, inhibited histamine-induced tonic relaxation. These findings suggest that histamine produced relaxation in circular smooth muscle of human gastric smooth muscle through H₂ receptor and NO/sGC pathways.

Roles of histamine on the expression of aldehyde dehydrogenase 1 in endometrioid adenocarcinoma cell line

Cancer-initiating cells (CICs) are a limited number of cells that are essential for maintenance, recurrence, and metastasis of tumors. Aldehyde dehydrogenase 1 (ALDH1) has been recognized as a marker of CICs. We previously reported that ALDH1-high cases of uterine endometrioid adenocarcinoma showed poor prognosis, and that ALDH1 high population was more tumorigenic, invasive, and resistant to apoptosis than ALDH1 low population. Histamine plays a critical role in cancer cell proliferation, migration, and invasion. Here, we examined the effect of histamine on ALDH1 expression in endometrioid adenocarcinoma cell line. The addition of histamine increased ALDH1 high population, which was consistent with the result that histamine enhanced the invasive ability and the resistance to anticancer drug. Among 4 types of histamine receptors, histamine H1 and H2 receptor (H1R and H2R) were expressed in endometrioid adenocarcinoma cell line. The addition of H1R agonist but not H2R agonist increased ALDH1. The antagonist H1R but not H2R inhibited the effect of histamine on ALDH1 expression. These results indicated that histamine increased the expression of ALDH1 via H1R but not H2R. These findings may provide the evidence for exploring a new strategy to suppress CICs by inhibiting ALDH1 expression with histamine.