Histamine metabolism and transport are deranged in human keratinocytes in oral lichen planus

H2 antihistamines: May be useful for combination therapies in cancer?

Cancer morbimortality is still a great concern despite advances in research and therapies. Histamine and its receptors' ligands can modulate different biological responses according to the cell type and the receptor subtype involved. Besides the wide variety of histamine functions in normal tissues, diverse roles in the acquisition of hallmarks of cancer such as sustained proliferative signaling, resistance to cell death, angiogenesis, metastasis, altered immunity and modified microenvironment have been described. This review summarizes the present knowledge of the various roles of histamine H2 receptor (H2R) ligands in neoplasias. A bioinformatic analysis of human tumors showed dissimilar results in the expression of the H2R gene according to tumor type when comparing malignant versus normal tissues. As well, the relationship between patients' survival parameters and H2R gene expression levels also varied, signaling important divergences in the role of H2R in neoplastic progression in different cancer types. Revised experimental evidence showed multiple effects of H2R antihistamines on several of the cited hallmarks of cancer. Interventional and retrospective clinical studies evaluated different H2R antihistamines in cancer patients with two main adjuvant uses: improving antitumor efficacy (which includes regulation of immune response) and preventing toxic adverse effects produced by chemo or radiotherapy. While there is a long path to go, research on H2R antihistamines may provide new opportunities for developing more refined combination therapeutic strategies for certain cancer types to improve patients' survival and health-related quality of life.

Emerging potential of phototherapy in management of symptomatic oral lichen planus: A systematic review of randomised controlled clinical trials

Phototherapy incorporating photobiomodulation therapy and antimicrobial photodynamic therapy has been utilised as antioxidants in symptomatic oral lichen planus (OLP) management; however, its role of intervention remains controversial. The aim of this systematic review of CRD42021227788 PROSPERO (an international prospective register of systematic reviews in health and social care) registration number was to oversee and determine phototherapy efficacy in patients with symptomatic OLP, identifying and bridging the literature gaps by proposing recommendations for future studies. A search strategy was developed in consistent with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Various electronic databases were exercised to search for randomised controlled clinical trials (RCTs). Several search engines were employed to analyse a total of 177 studies of which nine included. A wide range of utilised laser and light-emitted diode wavelengths between 630 and 808 nm and irradiance ranged between 10 and 13 mW/cm² were noted. 67% of studies reported a high risk of bias and a high heterogeneity obtained from numerical data for quantitative analysis, therefore meta-analysis was impossible to conduct. Despite inconsistency and diversity in phototherapy parameters, treatment protocols, photosensitiser (type, concentration and method of application) and outcome assessment tools, the majority of the studies showed positive results compared with standard care treatments. Hence, a necessity to perform well-designed RCTs with robust methodology is warranted, after acknowledging the current drawbacks and addressing the suggested recommendations highlighted in our review. Moreover, advanced knowledge in understanding further phototherapy-antioxidants molecular mechanistic in symptomatic OLP is required.

Systemic mastocytosis: The roles of histamine and its receptors in the central nervous system disorders

Mastocytosis is a rare disease of clonal hematological disorders characterized by a pathological accumulation of Mast Cells (MCs) in different tissues, with variable symptomatology and prognosis. Signs and symptoms of Systemic Mastocytosis (SM) are due to pathological infiltration of MCs and to the release of chemical mediators, mainly histamine. Patients with SM may also present with neurological symptoms or complications. The pathophysiology of these neurological disorders remains uncertain to this day, but it can be associated with the infiltration of tissue mastocytes, release of mastocytes' mediators or both. Moreover, there is a lot to understand about the role of neurological symptoms in SM and knowing, for example, what is the real frequency of neurological disorders in SM and if is present a relation between other SM subtypes, because it has been noted that the alteration of the histamine expression may be an initiating factor for susceptibility, gravity and progression of the epigenetic disease. In this review we explain the possible pathophysiological mechanism about neurological symptomatology found in some patients affected by SM, describing the role of histamine and its receptors in the nervous system and, in light of the results, what the future prospects may be for a more specific course of treatment.

Organic Cation Transporters in Brain Histamine Clearance: Physiological and Psychiatric Implications

Histamine acts as a neurotransmitter in the central nervous system and is involved in numerous physiological functions. Recent studies have identified the causative role of decreased histaminergic systems in various neurological disorders. Thus, the brain histamine system has attracted attention as a therapeutic target to improve brain function. Neurotransmitter clearance is one of the most important processes for the regulation of neuronal activity and is an essential target for diverse drugs. Our previous study has shown the importance of histamine N-methyltransferase for the inactivation of brain histamine and the intracellular localization of this enzyme; the study indicated that the transport system for the movement of positively charged histamine from the extracellular to intracellular space is a prerequisite for histamine inactivation. Several studies on in vitro astrocytic histamine transport have indicated the contribution of organic cation transporter 3 (OCT3) and plasma membrane monoamine transporter (PMAT) in histamine uptake, although the importance of these transporters in in vivo histamine clearance remains unknown. Immunohistochemical analyses have revealed the expression of OCT3 and PMAT on neurons, emphasizing the importance of investigating neuronal histamine uptake. Further studies using knockout mice or fast-scan cyclic voltammetry will accelerate the research on histamine transporters. In this review article, we summarize histamine transport assays and describe the candidate transporters responsible for histamine transport in the brain.

Nothing to sneeze at: Histamine and histamine receptors in oral carcinogenesis

Oral squamous cell carcinoma (OSCC), the most common oral malignancy, shows an increasing rate of incidence worldwide. In spite of the recent advances in cancer research, OSCC therapy continues to have unfavourable outcomes, and thus, patient's prognosis remains relatively poor. Current research has been devoted to identifying novel therapeutic targets also in the tumour microenvironment (TME). Histamine and its G-protein-coupled receptors (H1R-H4R) play vital roles in multiple cancer-associated processes in TME, where histamine is mainly produced by mast cells. However, oral epithelial cells were recently shown to produce low concentrations of histamine in autocrine and paracrine modes. These findings, together with the discovery of the high-affinity histamine H4 receptor, have led to a massive increase in our understanding of histamine functions. In this review, we aim to summarize the most recent findings regarding histamine and its receptors and their involvement in oral carcinogenesis-from oral potentially malignant disorders (OPMDs) to invasive OSCC. Importantly, histamine receptors are differentially expressed in OPMDs and OSCC. Furthermore, H1R and H4R are associated with clinicopathological characteristics of OSCC patients, suggesting a role in prognosis. Due to the enormous success of histamine-based medications, histamine receptors may also represent promising and viable drug targets in oral cancer.

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.

Human β-Defensin 2 Expression in Oral Epithelium: Potential Therapeutic Targets in Oral Lichen Planus

Human β-defensin 2 (hBD-2) is a potent antimicrobial peptide that participates in defense against invading bacteria. We recently showed that bacterial components and histamine, through histamine H4 receptor (H4R), are involved in the pathogenesis of the potentially malignant lesion, oral lichen planus (OLP). However, the underlying mechanisms remain unknown. We, therefore, investigated the role of hBD2–histamine crosstalk signaling in promoting OLP pathology. Biopsies from OLP and oral tongue squamous cell carcinoma (OTSCC) patients, and healthy controls were used. Two OTSCC cell lines and normal human oral keratinocytes (HOKs) were used. HBD-2 and other targets were mapped by immunostaining and analyzed by ImageJ2 software. The highly sensitive droplet-digital PCR technology and qRT-PCR were utilized to study the clinically derived and in vitro samples, respectively. H4R was challenged with the specific agonist HST-10 and inverse agonist ST-1007. HBD-2 was highly induced in OLP lesions. In contrast, hBD2 expression was attenuated in OTSCC tissues, while very low levels of hBD-2 messenger RNA (mRNA) were observed in OTSCC cells. Together with tumor necrosis factor-α (TNF-α), histamine upregulated hBD-2 mRNA expression in HOKs. Activation of H4R seems to modulate the expression of epithelial hBD-2. These findings suggest the involvement of hBD-2 in the pathogenesis of OLP and may, thus, be harnessed for therapeutic interventions in OLP.

Histamine pharmacology: from Sir Henry Dale to the 21st century

Histamine has been one of the most studied substances in medicine, playing a major role in diverse (patho)physiological processes. It elicits its multifaceted modulatory functions by activating four types of GPCRs, designated as H_1-4 . Despite the heterogeneity and the complexity of histamine receptor pharmacology, many discoveries over the past 100 years resulted in the development of H₁ antihistamines and H₂ -targeting 'blockbuster' therapeutics for the management of allergies and gastrointestinal disorders respectively. Recently, a first-in-class H₃ inverse agonist was approved for the treatment of narcolepsy, whereas H₄ antagonists are under clinical evaluation for their potential therapeutic exploitation in immune-related diseases. This review critically presents the past successes and drawbacks in histamine research, complemented by the modern conceptual innovations in molecular and receptor pharmacology. It targets both young and experienced researchers in an ongoing effort to stimulate novel insights for the dissection of the translational potential of histamine pharmacology. 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.

Extracellular interleukin-17F has a protective effect in oral tongue squamous cell carcinoma

BACKGROUND

Oral tongue squamous cell carcinoma (SCC) is characterized by early metastasis and poor prognosis. Interleukin-17F (IL-17F) plays a protective role in many tumors. However, IL-17F expression in oral tongue SCC tissue has not been investigated.

METHODS

Immunostaining of 83 oral tongue SCC specimens and blinded-scoring were used to map IL-17F expression, location, and distribution. Survival curves were constructed according to Kaplan-Meier method. The Cox proportional hazard model was applied for univariate and multivariate survival analyses.

RESULTS

Mast cells are the major source of IL-17F in oral tongue SCC. In multivariate analysis, only the extracellular mast cell-derived IL-17F at the tumor invasion front was associated with better disease-specific survival in patients with all-stages and early-stages of oral tongue SCC.

CONCLUSION

Extracellular mast cell-derived IL-17F is antitumorigenic in oral tongue SCC. It separates patients with early-stage disease who are at high risk from patients who are at low risk. Furthermore, when analyzing tentative prognostic molecules, we conclude that in addition to the staining intensity, attention must be paid to the cellular source, distribution, and location of the molecule.

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.