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The anaphylatoxin C3a triggers inflammation by binding to its specific G-protein-coupled C3a receptor (C3aR). Since the number of C3aR, which is expressed on the cell surface, affects the response to C3a, we investigated the expression levels of C3aR on human M2 macrophages in allergic situations where high levels of the Th2 cytokine IL-4 and histamine are present in a local microenvironment. The histamine H1 receptor (H1R), H2R and the H4R mRNA expressions were induced or up-regulated during the differentiation process of M2 macrophages. The presence of histamine or agonists targeting the H1R, H2R and, in particular, the H4R during in vitro differentiation from monocytes to macrophages modified the M2 phenotype by regulating the macrophage differentiation marker CD68 and CD163 expressions. In ­addition, the C3aR expression was also down-regulated by ­ST-1006 during this process. Histamine and ST-1006 down-regulated the expression of C3aR with different time kinetics on fully differentiated M2 macrophages. By analysing C3a-induced IL-6 mRNA expression, we observed a diminished response to C3a in ST-1006-treated M2 macrophages when compared to un-treated cells. Expression of C3 was not affected by histamine, whereas IL-4 strongly down-regulated C3aR and C3 expressions. Our data suggests that down-regulation of C3aR expression by mediators present in allergic situations such as IL-4 or histamine has an anti-inflammatory impact by reducing the sensitivity to C3a-induced down-stream signaling, thereby contributing to the regulation of local inflammatory responses in the skin.

Histamine is released from mast cells when tissues are inflamed or stimulated by allergens. Activation of histamine receptors and calcium influx via TRPV1 could be related to histamine-induced itch and skin inflammation. Quercetin is known to have anti-inflammatory and anti-itching effects. This study aims to understand whether quercetin can directly affect histamine-induced calcium influx in human keratinocyte. In it, we investigated quercetin, which acts on histamine-induced intracellular free calcium ([Ca2+]i) elevation in human keratinocyte. Changes in [Ca2+]i were measured using spectrofluorometry and confocal Imaging. We detected the expression of IL-8 after treatment of quercetin using qRT-PCR and evaluated its anti-itching effect in BALB/c mice. We also performed a docking study to estimate the binding affinity of quercetin to H4 receptors. We found that quercetin pretreatment decreased histamine-induced [Ca2+]i elevation in a concentration-dependent manner. The inhibitory effect of quercetin on histamine-induced [Ca2+]i elevation was blocked by JNJ7777120, a selective H4 antagonist, as well as by U73122, a PLC inhibitor, and by GF109203X, a PKC inhibitor. We also found that H4 agonist (4-methylhistamine)-induced [Ca2+]i elevation could be inhibited by quercetin. Moreover, the selective TRPV1 blocker capsazepine significantly suppressed the quercetin-mediated inhibition of histamine-induced [Ca2+]i elevation, whereas the TRPV4 blocker GSK2193874 had no effect. Last, quercetin decreased histamine and H4 agonist-induced IL-8 expression in keratinocyte and inhibited the scratching behavior-induced compound 48/80 in BALB/c mice. The molecular docking study also showed that quercetin exhibited high binding affinities with H4 receptors (autodock scores for H4 = −8.7 kcal/mol). These data suggest that quercetin could decrease histamine 4 receptor-induced calcium influx through the TRPV1 channel and could provide a molecular mechanism of quercetin in anti-itching, anti-inflammatory, and unpleasant sensations.

JNJ7777120, a histamine H4 receptor antagonist, was shown to be effective in different experimental settings of allergic inflammation, including contact hypersensitivity. Toll-like receptors (TLRs) are thought to function as a link between innate and adaptive immune responses to various haptens. Here, we studied the suppression of TLR signaling as a possible mechanism by which JNJ7777120 exerts its anti-inflammatory effects against the chemical hapten, fluorescein isothiocyanate (FITC). The potential anti-oxidant effect of JNJ7777120 in this model was also examined. Mice subjected to FITC sensitization and challenge showed significantly elevated plasma immunoglobulin E (IgE) level, ear interleukin-4 (IL-4), tumor necrosis factor-alpha (TNF-α), and thiobarbituric acid reactive substance (TBARS) contents as well as increased myeloid differentiation factor 88 (MyD88) gene expression, nuclear factor-kappa B p65 (NF-κB p65), and phospho-p38 mitogen-activated protein kinase (p-p38 MAPK) protein expression. This was accompanied by enhanced ear myeloperoxidase (MPO) and eosinophil peroxidase (EPO) activities as well as diminished glutathione (GSH) content and superoxide dismutase (SOD) activity. JNJ7777120 treatment perceivably reversed these effects, denoting profound anti-inflammatory and anti-oxidant character of JNJ7777120 which was confirmed by its mitigation of FITC-induced pathological changes in mouse ear. JNJ7777120 additionally enhanced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), providing a novel mechanism by which JNJ7777120 functions as an anti-oxidant in this model. To conclude, JNJ7777120 afforded a remarkable amendment of FITC skin insult by virtue of its anti-inflammatory and anti-oxidant effects; the mechanistic basis of these effects may include modulation of TLR and Nrf2 pathways.

Immunohistochemical staining for the lysosome-associated membrane protein 2 (LAMP-2) has been proposed previously as an alternative to electron microscopy to identify hepatic phospholipidosis. This study used LAMP-2 immunohistochemistry (IHC) to diagnose phospholipidosis in rats exhibiting renal tubular injury. Rats were administered toreforant, a histamine H4 receptor antagonist by oral gavage at a dose of 3, 10, or 100 mg/kg/d for 6 months. Hematoxylin and eosin staining revealed renal tubular epithelial cell vacuolation, hypertrophy, degeneration, and luminal dilation in the 100 mg/kg/d group animals. Renal tubular injury was confirmed using kidney injury marker 1 (KIM-1) IHC. The involvement of phosopholipidosis in the renal injury was investigated by LAMP-2. Adipophilin IHC was included to differentiate phospholipidosis from lipidosis. Increased LAMP-2 staining was observed in the 100 mg/kg/d group animals when compared to vehicle group animals. Lysosome-associated membrane protein-2 staining was most prominent in the outer stripe of the outer medulla where KIM-1 staining was also most prominent. By contrast, adipophilin staining was not increased. Phospholipidosis was also confirmed by electron microscopy. These data support the use of LAMP-2 IHC as a diagnostic tool and suggest an association between phospholipidosis and the renal tubular injury caused by toreforant.

Background The histamine H4 receptor (H4R) has attracted a lot of attention in terms of its role in antinociception. The N -Methyl- d -aspartic acid (NMDA) receptor is a well-characterized participant in pain pathways. However, it’s influence on H4R signaling is poorly understood. Thus, in the present study we investigated the effect of a selective H4R antagonist JNJ7777120 (25 mg/kg) and a NMDA receptor antagonist MK-801 (0.1–10 μg) on nociceptive thresholds in a rat acute pain model. Methods The influence of intrathecally ( it ), intracerebroventricularly ( icv ) and intraplantarly ( ipl ) administered MK-801 co-injected with JNJ7777120 administered intraperitoneally ( ip ) was determined in the modified Randall-Selitto paw pressure, the tail flick and plantar tests. Results Both ip JNJ7777120 as well as MK-801 delivered it and ipl increased nociceptive pain thresholds. It and ipl pretreatment with MK-801 additively augmented JNJ7777120 mechanical antinociception. A weaker effect was also observed after it co-administration with MK-801 and JNJ7777120 in the tail flick test. Intracerebroventricular MK-801 failed to produce any effect nor did ipl MK-801 in the plantar test. Conclusions The results show for the first time that the H4R and NMDA receptors play a significant role in antinociception in an acute non-inflammatory pain. Furthermore, the blockage of NMDA receptors at the peripheral and spinal, but not supraspinal sites produces a profound antinociceptive response upon simultaneous H4R antagonism. Thus, this study clearly demonstrates the relevance of NMDA and H4R receptors in the modulation of pain signals and that their role is not exclusively limited to their modulatory activity in inflammatory pain states.

Fil: Massari, Noelia A. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Laboratorio de Radioisotopos; Argentina Fil: Massari, Noelia A. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales. Departamento de Inmunología; Argentina Fil: Nicoud, Melisa B. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Laboratorio de Radioisotopos; Argentina Fil: Nicoud, Melisa B. Pontificia Universidad Católica Argentina. Faculta de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Biología Tumoral e Inflamación; Argenitna Fil: Nicoud, Melisa B. Consejo Nacional de Investigaciones Científicas; Argentina Fil: Sambuco, Lorena. Instituto de Inmunooncología; Argentina Fil: Martinel Lamas, Diego J. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Laboratorio de Radioisotopos; Argentina Fil: Martinel Lamas, Diego J. Pontificia Universidad Católica Argentina. Faculta de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Biología Tumoral e Inflamación; Argenitna Fil: Martinel Lamas, Diego J. Consejo Nacional de Investigaciones Científicas; Argentina Fil: Herrero Ducloux, María V. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales. Departamento de Patología; Argentina Fil: Blanco, Horacio. Hospital Municipal de Oncología Marie Curie; Argentina Fil: Rivera, Elena S. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Laboratorio de Radioisotopos; Argentina Fil: Medina, Vanina Araceli. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Laboratorio de Radioisotopos; Argentina Fil: Medina, Vanina Araceli. Pontificia Universidad Católica Argentina. Faculta de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Biología Tumoral e Inflamación; Argenitna Fil: Medina, Vanina Araceli. Consejo Nacional de Investigaciones Científicas; Argentina Abstract: The aims of the work were to improve our knowledge of the role of H4R in melanoma proliferation and assess in vivo the therapeutic efficacy of histamine, clozapine and JNJ28610244, an H4R agonist, in a preclinical metastatic model of melanoma. Additionally, we aimed to investigate the combinatorial effect of histamine and gamma radiation on the radiobiological response of melanoma cells. Results indicate that 1205Lu metastatic melanoma cells express H4R and that histamine inhibits proliferation, in part through the stimulation of the H4R, and induces cell senescence and melanogenesis. Daily treatment with H4R agonists (1 mg/kg, sc) exhibited a significant in vivo antitumor effect and importantly, compounds reduced metastatic potential, particularly in the group treated with JNJ28610244, the H4R agonist with higher specificity. H4R is expressed in benign and malignant lesions of melanocytic lineage, highlighting the potential clinical use of histamine and H4R agonists. In addition, histamine increased radiosensitivity of melanoma cells in vitro and in vivo. We conclude that stimulation of H4R by specific ligands may represent a novel therapeutic strategy in those tumors that express this receptor. Furthermore, through increasing radiation-induced response, histamine could improve cancer radiotherapy for the treatment of melanoma.

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

Although many studies have shown that histamine and its signaling regulate energy homeostasis through the central nervous system, their roles in adipose tissues remain poorly understood. Here, we identified that the histamine H4 receptor (HrH4) was highly expressed in adipocytes at a level higher than that of the other three receptors (i.e., HrH1, HrH2, and HrH3). The HrH4 expression in adipocytes responded to cold through thermogenesis and lipolysis, supported by results from both mouse and cell models. When HrH4 expression was knocked down in the subcutaneous white adipose tissue (scWAT), browning and lipolysis effects triggered by cold were ablated, and the oxygen consumption was also lowered both at the normal and cold conditions. Moreover, mice exhibited browned scWAT, accelerated metabolic rates, and tolerance to hypothermia when 4-methylhistamine (4MH), a selective HrH4 agonist, was adjacently injected to the scWAT. Consistent with these findings, 4MH also triggered the browning and lipolytic effects in cultured C3H10T1/2 adipocytes. Mechanically, we demonstrated that p38/MAPK and ERK/MAPK pathways were involved in these processes. In conclusion, our findings have uncovered an effective role of HrH4 in adipose tissue browning.

Patients with liver diseases often suffer from chronic itch, yet the pruritogen(s) and receptor(s) remain largely elusive. Here, we identify bile acids as natural ligands for MRGPRX4. MRGPRX4 is expressed in human dorsal root ganglion (hDRG) neurons and co-expresses with itch receptor HRH1. Bile acids elicited Ca2+ responses in cultured hDRG neurons, and bile acids or a MRGPRX4 specific agonist induced itch in human subjects. However, a specific agonist for another bile acid receptor TGR5 failed to induce itch in human subjects and we find that human TGR5 is not expressed in hDRG neurons. Finally, we show positive correlation between cholestatic itch and plasma bile acids level in itchy patients and the elevated bile acids is sufficient to activate MRGPRX4. Taken together, our data strongly suggest that MRGPRX4 is a novel bile acid receptor that likely underlies cholestatic itch in human, providing a promising new drug target for anti-itch therapies.

The locus coeruleus (LC) adrenergic nuclei constitute a pain-control inhibitory system nucleus implicated in descending modulation of pain through the action on spinal α

Fil: Nicoud, Melisa Beatriz. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Biología Tumoral e Inflamación; Argentina Fil: Nicoud, Melisa Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sterle, Helena A. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. División de Neuroinmunomodulación y Oncología Molecular; Argentina Fil: Sterle, Helena A. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Massari, Noelia A. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales. Departamento de Inmunología; Argentina Fil: Táquez Delgado, Mónica Alejandra. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Biología Tumoral e Inflamación; Argentina Fil: Táquez Delgado, Mónica Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Nicoud, Melisa Beatriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Laboratorio de Radioisótopos,; Argentina Fil: Formoso, Karina. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Farmacología y Función de los Canales Iónicos; Argentina Fil: Formoso, Karina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Herrero Ducloux, María V. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales. Departamento de Patología; Argentina Fil: Martinel Lamas, Diego José. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Biología Tumoral e Inflamación; Argentina Fil: Martinel Lamas, Diego José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cremaschi, Graciela A. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. División de Neuroinmunomodulación y Oncología Molecular; Argentina Fil: Cremaschi, Graciela A. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Medina, Vanina A. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Biología Tumoral e Inflamación; Argentina Fil: Medina, Vanina A. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Medina, Vanina A. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Laboratorio de Radioisótopos,; Argentina Abstract: Background: The aim of this work was to improve the knowledge of the role of histamine in breast cancer by assessing the therapeutic efficacy of histamine and histamine H4 receptor (H4R) ligands in a triple-negative breast cancer (TNBC) model developed in immunocompetent hosts. By using publicly available genomic data, we further investigated whether histidine decarboxylase (HDC) could be a potential biomarker. Methods: Tumours of 4T1 TNBC cells were orthotopically established in BALB/c mice. Treatments employed (mg kg−1): histamine (1 and 5), JNJ28610244 (H4R agonist, 1 and 5) and JNJ7777120 (H4R antagonist, 10). Results: Increased HDC gene expression is associated with better relapse-free and overall survival in breast cancer patients. Histamine treatment (5 mg kg−1) of 4T1 tumour-bearing mice reduced tumour growth and increased apoptosis. Although no immunomodulatory effects were observed in wild-type mice, significant correlations between tumour weight and cytotoxic lymphocyte infiltration were detected in H4R knockout mice. H4R agonist or antagonist differentially modulated tumour growth and immunity in 4T1 tumour-bearing mice. Conclusions: Histamine plays a complex role and stands out as a promising drug for TNBC treatment, which deserves to be tested in clinical settings. HDC expression level is associated with clinicopathological characteristics, suggesting a prognostic value in breast cancer.

Autism is a neurodevelopmental disorder characterized by deficits and qualitative impairments in communication and implicit skill learning. Its prevalence is higher than previous estimates, and treatments have limited efficacy and are costly. Here, we assessed the therapeutic potential of JNJ77777120 (JNJ), a histamine-4 receptor (H4R) antagonist, using BTBR T

Release of histamine from mast cells and basophils in inflammatory diseases of the nose and paranasal sinuses has been demonstrated in allergic and non-allergic processes.A selective literature search was conducted in PubMed and Medline, and publications in German-language journals were additionally analyzed.The histamine receptors HH

Histamine is a major peripheral inflammatory mediator and a neurotransmitter in the central nervous system. We have reported that histamine induces microglia activation and releases proinflammatory factors in primary cultured microglia. Whether histamine has similar effects in vivo is unknown. In the present study, we aimed to investigate the role of histamine and its receptors in the release of inflammatory mediators and activation of microglia in rat brain. We site-directed injected histamine, histamine receptor agonists or histamine receptor antagonists in the rat lateral ventricle using stereotaxic techniques. Flow cytometry was employed to determine histamine receptor expression in rat microglia. Microglia activation was assessed by Iba1 immunohistochemistry. The levels of tumour necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and interleukin-10 (IL-10) were measured with commercial enzyme-linked immunosorbent assay (ELISA) kits, TNF-α, IL-1β and IL-10 mRNA expressions were determined with Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). We found that all four types of histamine receptors were expressed in rat brain microglia. Histamine was able to induce microglia activation and subsequent production of the inflammatory factors TNF-α, IL-1β and IL-10, and these effects were partially abolished by H

Purpose: Fexofenadine (FXF) is the active metabolite of terfenadine with selective peripheral H 1 receptor antagonist activity. FXF is a third-generation antihistamine, non-sedating, rapid and very long acting used in symptoms associated with allergic diseases such as allergic rhinitis, asthma and dermatitis. The pleiotropic effects of histamine are mediated by four types of receptors that belong to the G-protein-coupled receptor family: histamine H 1 receptor (HRH-1), histamine H 2 receptor, histamine H 3 receptor, and histamine H 4 receptor. Our hypothesis is that HRH-4 opens new possibility in treatment in allergy diseases and FXF could be the antagonist of both HRH-1 and HRH-4. Methods: We isolated a peripheral blood mononuclear cell (PBMC) from children with diagnosed allergies and healthy – control group and measured the HRH-1 and HRH-4 mRNA gene expression using Quantitive Real-Time PCR. We obtained the results from basal gene expression and after FXF and histamine stimulation. Results: HRH-1 mRNA basal gene expression shows significantly higher, and HRH-4 shows significantly lower expression in allergy group compared to control. In both groups HRH-1 mRNA gene expression was observed as statistically significant increased after histamine stimulation compared to cells not treated, while in HRH-4 only in allergy group we observed statistical increase. FXF successively blocked histamine affinity in HRH-1 mRNA gene expression but not in HRH-4, where we not observed any reaction. Conclusions : Results clearly overturned our hypothesis about the possibility of using FXF to block over-expression HRH-4 and open new way of treatment in allergy diseases.

Studies have shown that an injection with the histamine H4 receptor agonist VUF-8430 modulates emotional memory processes. In the present study, the aim was to verify if intraperitoneal (ip) injection of VUF-8430 (500 ng/kg) in mice affects the synthesis of proteins required for memory consolidation processes by activating the phosphorylation of CREB (pCREB) in classical structures linked to emotional memory (prefrontal cortex, amygdala, and hippocampus) and the cerebellar vermis, a structure that has also been recently implicated in emotional memory. The results obtained using western blot analysis demonstrated that VUF-8430 induced a decrease in CREB and pCREB levels in the cerebellar vermis and prefrontal cortex, suggesting that this dose impaired the activation of cell signaling pathways in these structures. There was no change in protein expression in the amygdala and hippocampus. Our results are preliminary, and further investigations are needed to investigate the role of the H4 receptors in the central nervous system.

We previously reported that hypothalamic tumor necrosis factor-alpha (TNF-α) mRNA expression via histamine H

Background: Although the role of histamine H4 receptor (H4R) in immune cells is being extensively investigated, its immunomodulatory function in cancer is completely unknown. This study aimed to investigate the role of H4R in antitumour immunity in a model of triple-negative breast cancer. Methods: We evaluated growth parameters, histological characteristics and the composition of tumour, splenic and tumour draining lymph node (TDLN) immune subsets, in a syngeneic model, developed orthotopically with 4T1 cells in H4R knockout (H4R-KO) and wild-type mice. Results: Mice lacking H4R show reduced tumour size and weight, decreased number of lung metastases and percentage of CD4 + tumour-infiltrating T cells, while exhibiting increased infiltration of NK cells and CD19 + lymphocytes. Likewise, TDLN of H4R-KO mice show decreased CD4 + T cells and T regulatory cells (CD4 + CD25 + FoxP3 + ), and increased percentages of NK cells. Finally, H4R-deficient mice show decreased Tregs in spleens and non-draining lymph nodes, and a negative correlation between tumour weight and the percentages of CD4 + , CD19 + and NK splenic cells, suggesting that H4R also regulates antitumour immunity at a systemic level. Conclusions: This is the first report that demonstrates the participation of H4R in antitumour immunity, suggesting that H4R could be a target for cancer treatment. Fil: Sterle, Helena Andrea. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina Fil: Nicoud, Melisa Beatriz. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina Fil: Massari, Noelia Andrea. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; Argentina Fil: Táquez Delgado, Mónica Alejandra. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina Fil: Herrero Ducloux, María Verónica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; Argentina Fil: Cremaschi, Graciela Alicia. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina Fil: Medina, Vanina Araceli. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina

Epithelial thymic stromal lymphopoietin (TSLP) promotes Th2 inflammatory responses through induction of OX40 ligand (OX40L) on dendritic cells in allergic rhinitis (AR). Emerging evidence supports the important role of histamine H4 receptor (H4R) in allergic inflammation. This study aimed to investigate the effects of H4R in Th2-cytokine profile mediated by TSLP in AR. Human nasal epithelial cells (HNECs) from AR patients were stimulated with histamine in the presence or absence of H4R agonist (4-methylhistamine, 4-MH) and antagonist (NJ7777120, JNJ) or H1R agonist (2-pyridylethylamine). TSLP protein was measured by Western blotting and ELISA. To further elucidate the role of H4R in the in vivo situation of experimental AR, rats were sensitized and treated with JNJ or 4-MH. TSLP and OX40 ligand (OX40L) in the nasal mucosa were assayed by Western blotting. Th2 cytokines including interleukin-4, 5 and 13 in nasal lavage fluids were detected by ELISA. Histamine alone did not induce TSLP production by HNECs. The pre-incubation with 4-MH prior to histamine promoted TSLP expression, which was inhibited by the stimulation with JNJ prior to histamine and 4-MH. The pre-incubation with 2-pyridylethylamine before histamine stimulation had no impact on TSLP production. In AR rats, the levels of TSLP and OX40L protein were increased as well as Th2 cytokines, which was further up-regulated by 4-MH treatment, while JNJ treatment attenuated these effects. H4R activation induced TSLP production by HNECs, which up-regulated OX40L expression in the nasal mucosa of sensitized rats. These factors promoted Th2-cytokine profile in AR.

International audience; AIM:A Phase 1 study was performed to evaluate safety, pharmacokinetics (PK) and pharmacodynamics (PD) of the selective histamine H4 receptor antagonist SENS-111, an oral small molecule.METHODS:One hundred healthy subjects were randomized in a placebo-controlled, double-blind study evaluating single-ascending doses (SAD; 100-500 mg) and multiple-ascending doses (MAD; 50-150 mg day-1 , 4 days; 200-250 mg day-1 , 7 days). Effects of SENS-111 on nystagmus and vertigo induced by modified caloric tests were measured in the MAD studies. Population PK and PK/PD models were developed using a nonlinear mixed-effects approach.RESULTS:SENS-111 was well tolerated with mild to moderate events. No sedation was reported. A maximal tolerated dose was not reached. Dose-proportional increases in concentrations were seen up to 200 mg and more than dose-proportional thereafter, with mean half-life between 24 and 56 h. The caloric test induced mild but measurable vertigo and nystagmus with large intra/inter-individual variation for all parameters. SENS-111 did not significantly impact nystagmus but significantly improved latency of vertigo appearance/disappearance, duration and European Evaluation of Vertigo questionnaire parameters vs. baseline. A two-compartment model with first-order absorption, distribution and elimination best fit the data. PK/PD indirect modelling applied to vertigo duration and latency of appearance indicated maximum activity between 100 and 500 ng ml-1 plasma concentrations, corresponding to 100 and 200 mg day-1 , which are appropriate for clinical efficacy evaluations in vestibular diseases.CONCLUSIONS:SENS-111 is a well-tolerated first-in-class H4 receptor antagonist with acceptable PK for oral daily dosing. PK/PD modelling determined plasma concentrations and doses for efficacy studies in patients with vertigo symptoms.

Synthesis and biological evaluation of a new class of histamine H4 receptor ligands, distinct from the previously reported chemotypes, are described. A virtual screening of our corporate compound collection identified a hit with an undesired dual H3R/H4R activity. Chemical exploration led to the discovery of a more potent and selective 2-benzothiazolylphenylmethyl ether lead compound.

Background Epidermal growth factor receptor (EGFR) inhibitor gefitinib (Iressa) is used for treating non-small cell lung cancer. Gefitinib also induces differentiation in acute myeloid leukemia (AML) cell lines and patient samples lacking EGFR by an unknown mechanism. Here we dissected the mechanism of gefitinib action responsible for its EGFR-independent effects. Methods Signaling events were analyzed by homogenous time-resolved fluorescence and immunoblotting. Cellular proliferation and differentiation were assessed by ATP measurement, trypan blue exclusion, 5-bromo-2′-deoxyuridine incorporation and flow-cytometry. Gefitinib and G protein-coupled receptor (GPCR) interactions were assessed by β-arrestin recruitment, luciferase and radioligand competition assays. Role of histamine receptors (HR) in gefitinib actions were assessed by HR knockdown or pharmacological modulation. EGFR and HR interaction was assessed by co-immunoprecipitation. Results Gefitinib reduced cyclic AMP content in both AML and EGFR-expressing cells and induced ERK phosphorylation in AML cells. Dibutyryl-cAMP or PD98059 suppressed gefitinib-induced AML cell cytostasis and differentiation. Gefitinib bound to and modulated HRs with subtype selectivity. Pharmacological or genetic modulations of H2 and H4 HRs (H2R and H4R) not only suppressed gefitinib-induced cytostasis and differentiation of AML cells but also blocked EGFR and ERK1/2 inhibition in MDA-MB-231 cells. Moreover, in MDA-MB-231 cells gefitinib enhanced EGFR interaction with H4R that was blocked by H4R agonist 4-methyl histamine (4MH). Conclusion HRs play critical roles in anti-cancer effects of gefitinib in both EGFR-deficient and EGFR-rich environments. General significance We furnish fresh insights into gefitinib functions which may provide new molecular clues to its efficacy and safety issues.

Fibrosis of lung tissue is a disease where a chronic inflammatory process determines a pathological remodelling of lung parenchyma. The animal model obtained by intra-tracheal administration of bleomycin in C57BL/6 mice is one of the most validated murine model. Bleomycin stimulates oxidative stress and the production of pro-inflammatory mediators. Histamine H 4 R have recently been implicated in inflammation and immune diseases. This study was focused to investigate the effects of H 4 R ligands in the modulation of inflammation and in the reduction of lung fibrosis in C57BL/6 mice treated with bleomycin. C57BL/6 mice were treated with vehicle, JNJ7777120 (JNJ, selective H 4 R antagonist) or ST-1006 (partial H 4 R agonist), ST-994 (H 4 R neutral antagonist) and ST-1012 (inverse H 4 R agonist) at equimolar doses, released by micro-osmotic pumps for 21 days. Airway resistance to inflation was assayed and lung samples were processed to measure malondialdehyde (TBARS); 8-hydroxy-2⿲-deoxyguanosine (8OH d G); myeloperoxidase (MPO); COX-2 expression and activity as markers of oxidative stress and inflammation. Fibrosis and airway remodelling were evaluated throughout transforming growth factor-β (TGF-β), percentage of positive Goblet cells, smooth muscle layer thickness determination. Our results indicated that JNJ, ST-994 and ST-1012 decreased inflammation and oxidative stress markers, i.e. the number of infiltrating leukocytes evaluated as lung tissue MPO, COX-2 expression and activity, TBARS and 8OH d G production. They also reduced the level of TGF-β, a pro-fibrotic cytokine, collagen deposition, thickness of smooth muscle layer, Goblet cells hyperplasia; resulting in a decrease of airway functional impairment. The results here reported clearly demonstrated that H 4 R ligands have a beneficial effect in a model of lung fibrosis in the mouse, thus indicating that H 4 R antagonists or inverse agonists could be a novel therapeutic strategy for lung inflammatory diseases.

Clozapine is an effective antipsychotic for treatment-resistant schizophrenia, but can cause fatal hematopoietic toxicity as agranulocytosis. To elucidate the mechanism of hematopoietic toxicity induced by clozapine, we developed an in vitro assay system using HL-60 cells, and investigated the effect on hematopoiesis. HL-60 cells were differentiated by all-trans retinoic acid (ATRA) into three states according to the following hematopoietic process: undifferentiated HL-60 cells, those undergoing granulocytic ATRA-differentiation, and ATRA-differentiated granulocytic cells. Hematopoietic toxicity was evaluated by analyzing cell survival, cell proliferation, granulocytic differentiation, apoptosis, and necrosis. In undifferentiated HL-60 cells and ATRA-differentiated granulocytic cells, both clozapine (50 and 100μM) and doxorubicin (0.2µM) decreased the cell survival rate, but olanzapine (1-100µM) did not. Under granulocytic differentiation for 5days, clozapine, even at a concentration of 25μM, decreased survival without affecting granulocytic differentiation, increased caspase activity, and caused apoptosis rather than necrosis. Histamine H4 receptor mRNA was expressed in HL-60 cells, whereas the expression decreased under granulocytic ATRA-differentiation little by little. Both thioperamide, a histamine H4 receptor antagonist, and DEVD-FMK, a caspase-3 inhibitor, exerted protection against clozapine-induced survival rate reduction, but not of live cell counts. 4-Methylhistamine, a histamine H4 receptor agonist, decreased the survival rate and live cell counts, as did clozapine. HL-60 cells under granulocytic differentiation are vulnerable under in vitro assay conditions to hematopoietic toxicity induced by clozapine. Histamine H4 receptor is involved in the development of clozapine-induced hematopoietic toxicity through apoptosis, and may be a potential target for preventing its occurrence through granulocytic differentiation.

Background Signaling through histamine receptors on dendritic cells (DCs) may be involved in the effector phase of peanut-induced intestinal anaphylaxis. Objectives The objective of this study was to determine the role of histamine H1 (H1R) and H4 receptors (H4R) in intestinal allergic responses in a model of peanut allergy. Methods Balb/c mice were sensitized and challenged with peanut. During the challenge phase, mice were treated orally with the H1R antagonist, loratadine, and/or the H4R antagonist, JNJ7777120. Bone marrow-derived DCs (BMDCs) were adoptively transferred to nonsensitized WT mice. Symptoms, intestinal inflammation, and mesenteric lymph node and intestine mucosal DCs were assessed. Effects of the drugs on DC chemotaxis, calcium mobilization, and antigen-presenting cell function were measured. Results Treatment with loratadine or JNJ7777120 individually partially suppressed the development of diarrhea and intestinal inflammation and decreased the numbers of DCs in the mesenteric lymph nodes and lamina propria. Combined treatment with both drugs prevented the development of diarrhea and intestinal inflammation. In vitro, the combination suppressed DC antigen-presenting cell function to T helper cells and DC calcium mobilization and chemotaxis to histamine. Conclusion Blockade of both H1R and H4R in the challenge phase had additive effects in preventing the intestinal consequences of peanut sensitization and challenge. These effects were mediated through the limitation of mesenteric lymph node and intestinal DC accumulation and function. Identification of this histamine H1R/H4R-DC-CD4+ T-cell axis provides new insights into the development of peanut-induced intestinal allergic responses and for prevention and treatment of peanut allergy.

Background Natural Killer cells (NK cells) are identified as pivotal mediators in allergic skin diseases and accumulate in lesions of atopic dermatitis (AD) patients. Histamine levels are increased in these lesions and histamine is involved in chemotaxis in dendritic cells and NK cells. Objective The aim of this study was to determine if the histamine H4 receptor (H4R) mediates NK cell chemotaxis and whether it influences interplay between NK cells and dendritic cells during the early phase of allergic inflammation. Methods Chemotactic function of the H4R as well as the influence of the H4R on the cytokine profile of an NK cell-dendritic cell co-culture was studied in vitro. The effect of H4R activation on NK cell migration, NK cell-dendritic cell interaction and cytokine levels in the skin was further characterized in the murine TDI model of allergic dermatitis. Additionally, the impact of the H4R on dermal NK cells was determined in the ovalbumin (OVA)- induced allergic dermatitis model, comparing wild type and H4R knockout mice. Results The selective H4R agonist ST-1006 induced NK cell chemotaxis in vitro, which was inhibited with the H4R antagonist JNJ7777120. In vivo, mice treated with TDI plus ST-1006 topically onto the ear, showed significantly enhanced ear swelling and an increased number of NK cells compared to just allergen challenged ears. CCL17 levels in the ear were also significantly increased 8 h after allergen challenge. Histology revealed that the main source for increased CCL17 were dendritic cells. These effects could be blocked using the H4R antagonist JNJ7777120. In the chronic model of allergic dermatitis, OVA induced NK cell migration into lesional skin sites. The number of NK cells was lower in OVA-sensitized H4R knockout mice compared to wild type mice. Conclusions These results identify the H4R as a new target controlling NK cell migration and NK cell-dendritic cell interaction in the skin during early allergic inflammation. These results further suggest that blocking the H4R in the skin might be beneficial in diseases like AD.

Objective.To assess toreforant (selective histamine H4 receptor antagonist) in active rheumatoid arthritis (RA).Methods.In a phase IIa, double-blind, placebo-controlled test, 86 patients were randomized (2:1) to once-daily toreforant 100 mg or placebo for 12 weeks. In phase IIb, double-blind, placebo-controlled, dose-range–finding evaluations, 272 patients were randomized (1:1:1:1) to once-daily placebo or toreforant 3/10/30 mg. Primary efficacy endpoints for both studies were Week 12 changes in 28-joint Disease Activity Score–C-reactive protein (DAS28-CRP).Results.Phase IIa testing was terminated prematurely (patient fatality; secondary hemophagocytic lymphohistiocytosis). Posthoc analyses indicated toreforant 100 mg/day reduced RA signs/symptoms through Week 12. Phase IIb testing, however, showed no significant Week 12 improvement in DAS28-CRP with toreforant.Conclusion.Toreforant was not effective in phase IIb testing.

BACKGROUND: Histamine is a key immunoregulatory mediator in immediate-type hypersensitivity reactions and chronic inflammatory responses, in particular histamine suppresses proinflammatory responses to bacterial ligands, through histamine receptor 2 (H2R). The aim of this study was to investigate the effects of histamine and H2R on bacteria-induced inflammatory responses in patients with IBD. METHODS: Peripheral blood mononuclear cells (PBMCs) were obtained from patients with Crohn's disease, patients with ulcerative colitis, and healthy controls. PBMC histamine receptor expression was evaluated by flow cytometry. Cytokine secretion following Toll-like receptor (TLR)-2, TLR-4, TLR-5, or TLR-9 stimulation in the presence or absence of histamine or famotidine (H2R antagonist) was quantified. Biopsy histamine receptor gene expression was evaluated using reverse transcription-polymerase chain reaction. The in vivo role of H2R was evaluated in the T-cell transfer murine colitis model. RESULTS: The percentage of circulating H2R monocytes was significantly reduced in patients with IBD. Histamine effectively suppressed TLR-induced cytokine secretion from healthy volunteer PBMCs but not for PBMCs from patients with IBD. Famotidine reversed this suppressive effect. H1R, H2R, and H4R gene expression was increased in inflamed gastrointestinal mucosa compared with noninflamed mucosa from the same patient and expression levels correlated with proinflammatory cytokine gene expression. Mice receiving lymphocytes from H2R donors, or treated with famotidine, displayed more severe weight loss, higher disease scores and increased numbers of mucosal IFN-γ and IL-17 T cells. CONCLUSION: Patients with IBD display dysregulated expression of histamine receptors, with diminished anti-inflammatory effects associated with H2R signaling. Deliberate manipulation of H2R signaling may suppress excessive TLR responses to bacteria within the gut.

BACKGROUND IgE-mediated cross-linking of FceRI results in the release of mediators stored in basophil granules, such as histamine and proteases, and in the de novo synthesis of sulfidoleukotrienes. OBJECTIVE In this study, we investigated the role of the histamine receptors, in particular that of the histamine H4 receptor (H4R), in modulating human basophil function. METHODS The mRNA expression of the histamine receptors was measured by real-time PCR. Migration of basophils was assessed using the modified Boyden chamber technique. The expression levels of CD63 and CD203c on the cell surface and the sulfidoleukotriene release were determined by flow cytometry and ELISA, respectively. RESULTS We could show that highly purified basophils express the H1R, H2R, and H4R but not the H3R mRNA. Human basophils expressed higher H4R mRNA levels as compared to the expression levels of the H1R (P < 0.01). Histamine and the H4R agonist ST-1006 initiated active migration of basophils (P < 0.001). A significant reduction in FceRI cross-linking-mediated surface expression of CD63 and CD203c was observed on basophils after pre-incubation with histamine or the specific H4R agonist ST-1006 (P < 0.01). The synthesis and release of sulfidoleukotrienes from basophils after activation with different stimuli, by FceRI cross-linking or by stimulation with hymenoptera venom allergens, were significantly reduced by histamine or the H4R agonist ST-1006 (P < 0.05-0.001). CONCLUSION These data imply that the H4R regulates IgE-dependent processes in human basophils and provides a novel function of the H4R preventing an overwhelming immune reaction by engagement of a negative feedback loop.

2-Cyano-1-[4-(1H-imidazol-4-yl)butyl]-3-[2-(phenylsulfanyl)ethyl]guanidine (UR-PI376, 1) is a potent and selective agonist of the human histamine H4 receptor (hH4R). To gain information on the active conformation, we synthesized analogues of 1 with a cyclopentane-1,3-diyl linker. Affinities and functional activities were determined at recombinant hHxR (x: 1-4) subtypes on Sf9 cell membranes (radioligand binding, [(35)S]GTPγS, or GTPase assays) and in part in luciferase assays on human or mouse H4R (HEK-293 cells). The most potent H4R agonists among 14 racemates were separated by chiral HPLC, yielding eight enantiomerically pure compounds. Configurations were assigned based on X-ray structures of intermediates and a stereocontrolled synthetic pathway. (+)-2-Cyano-1-{[trans-(1S,3S)-3-(1H-imidazol-4-yl)cyclopentyl]methyl}-3-[2-(phenylsulfanyl)ethyl]guanidine ((1S,3S)-UR-RG98, 39a) was the most potent H4R agonist in this series (EC50 11 nM; H4R vs H3R,100-fold selectivity; H1R, H2R, negligible activities), whereas the optical antipode proved to be an H4R antagonist ([(35)S]GTPγS assay). MD simulations confirmed differential stabilization of the active and inactive H4R state by the enantiomers.

We examined the inhibitory effect of a histamine 4 receptor (H4R) antagonist (JNJ7777120) on CCL17 and CCL22 chemokine production by human monocyte-derived Langerhans cells (MoLC) in patients with atopic dermatitis (AD) and healthy controls (HC). We confirmed the significantly higher production of both CCL17 and CCL22 in the MoLC of AD patients compared with HC. The H4R antagonist significantly inhibited the production of both CCL17 and CCL22 in the MoLC of AD patients. With regard to TLR2-signaled enhancement, peptidoglycan (PGN)-enhanced production of CCL17 and CCL22 by MoLC was inhibited by the H4R. Immunoblotting analysis demonstrated that phosphorylated p38 mitogen-activated protein kinase was induced by PGN and that this enhancement was attenuated by the application of the H4R antagonist. These data indicate that H4 signaling modulates the production of T-helper 2 chemokine in MoLC and contributes to chronic inflammation in AD patients. Our data suggest a possible novel therapeutic approach using a H4R antagonist in the treatment of patients with AD.

Distinct diaminopyrimidines, for example, 4-(4-methylpiperazin-1-yl)-5,6-dihydrobenzo[h]quinazolin-2-amine are histamine H4 receptor (H4R) antagonists and show high affinity to the H4R, but only a moderate affinity to the histamine H1 receptor (H1R). Within previous studies it was shown that an aromatic side chain with a distinct distance to the basic amine and aromatic core is necessary for affinity to the human H1R (hH1R). Thus, a rigid aminopyrimidine with a tricyclic core was used as a lead structure. There, (1) the flexible aromatic side chain was introduced, (2) the substitution pattern of the pyrimidine core was exchanged and (3) rigidity was decreased by opening the tricyclic core. Within the present study, two compounds with similar affinity in the one digit μM range to the human H1R and H4R were identified. While the affinity at the hH1R increased about 4- to 8-fold compared to the parent diaminopyrimidine, the affinity to the hH4R decreased about 5- to 8-fold. In addition to the parent diaminopyrimidine, two selected compounds were docked into the H1R and H4R and molecular dynamic studies were performed to predict the binding mode and explain the experimental results on a molecular level. The two new compounds may be good lead structures for the development of dual H1/H4 receptor ligands with affinities in the same range.

Epithelial-mesenchymal transition (EMT) contributes to cell invasion and metastasis during the progression of epithelial cancers. Though preclinical evidence suggests a role for histamine H4 receptor (H4R) in breast cancer growth, its function in the EMT is less known. In this study we proposed to investigate the effects of H4R ligands on EMT and mammosphere formation as a surrogate assay for cancer stem cells in breast cancer cells with different invasive phenotype. We also investigated the participation of Src and TGF-β signaling in these events. Breast cancer cells were treated with the H4R agonists Clobenpropit, VUF8430 and JNJ28610244 and the H4R antagonist JNJ7777120. Immunodetection studies showed cytoplasmic E-cadherin, cytoplasmic and nuclear beta-catenin, nuclear Slug and an increase in vimentin and α-smooth muscle actin expression. There was also an enhancement in cell migration and invasion assessed by transwell units. All these effects were prevented by JNJ7777120. Moreover, H4R agonists induced an increase in phospho-Src levels detected by Western blot. Results revealed the involvement of phospho-Src in EMT events. Upon treatment with H4R agonists there was an increase in phospho-ERK1/2 and TGF-β1 levels by Western blot, in Smad2/3 positive nuclei by indirect immunofluorescence, and in tumor spheres formation by the mammosphere assay. Notably, the selective TGF-β1 kinase/activin receptor-like kinase inhibitor A83-01 blocked these effects. Moreover, cells derived from mammospheres exhibited higher Slug expression and enhanced migratory behavior. Collectively, findings support the interaction between H4R and TGF-β receptor signaling in the enhancement of EMT features and mammosphere formation and point out intracellular TGF-β1 as a potential mediator of these events. Fil: Galarza, Tamara Ester. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentina Fil: Táquez Delgado, Mónica Alejandra. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mohamad, Nora A.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina Fil: Martin, Gabriela Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina Fil: Cricco, Graciela P.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina

In a double-blind, placebo-controlled, multiple-dose study, we assessed the molecular mechanism of action of the selective histamine-4-receptor antagonist toreforant.Patients with active rheumatoid arthritis (RA) despite methotrexate were randomized (3:1) to toreforant 30 mg/day (weeks 0-52) or placebo (weeks 0-12) followed by toreforant 30 mg/day (weeks 12-52).Primary biomarker analyses comprised 39 different proteins/mRNA transcripts measured in synovial biopsy (n = 39) and/or time-matched serum (n = 15) samples collected at baseline and week 6. Clinical response was assessed using C-reactive protein-based 28-joint disease activity scores. Data were summarized using descriptive statistics.Among 21 randomized, treated patients (toreforant-16, placebo-5), 18 (toreforant-13, placebo-5) completed the 12-week double-blind period (none completed open-label treatment) prior to the early study termination. Biomarker profiling indicated potential modest effects of toreforant on gene expression of histamine-1-receptor, tumor necrosis factor-alpha, and interleukin-8 in synovium. Potential trends between biomarkers and clinical response were observed with synovial monocyte chemoattractant protein-4 and phosphorylated extracellular-signal-regulated kinases and serum matrix metalloproteinase-3. Minimal synovial gene expression of interleukins-17A and 17F was detected.While clear biomarker signals associated with toreforant pharmacology in RA patients were not identified, modest associations between biomarkers and clinical response were noted. Synovial expression of interleukins-17A/17F was minimal. Limited sample size warrants cautious interpretation.

This study focuses on the design, synthesis, molecular modeling and biological evaluation of a novel group of alkyl-1,3,5-triazinyl-methylpiperazines. New compounds were synthesized and their affinities for human histamine H

We previously designed and synthesized a series of histamine analogues with an imidazolylcyclopropane scaffold and identified potent non-selective antagonists for histamine H

Toreforant is a selective histamine H4 receptor antagonist. H4 receptor activation may play a role in immune-mediated inflammation in psoriasis.To evaluate Toreforant efficacy and safety in patients with moderate-to-severe psoriasis.Biologic-naïve patients were to be treated (30, 60, or 3 mg Toreforant or placebo) for 12 weeks and followed through week 16. In this adaptive-design study, assignments were guided by interim analyses. Primary and major secondary efficacy endpoints, evaluated using Bayesian analyses, were the proportions of patients achieving ≥75% improvement in Psoriasis Area and Severity Index (PASI) from baseline and achieving Investigator's Global Assessment (IGA) of cleared (0) or minimal (1), respectively, at week 12.Per interim analyses results, patients were randomized to 30 (n = 30) or 60 mg (n = 26) Toreforant or placebo (n = 6). The estimated mean difference in the PASI 75 response rate at week 12 from the posterior distributions compared to placebo was 14.1% (95% credible interval [CI], -0.1% to 30.9%) and 8.9% (95% CI, -5.0% to 24.3%) with 30 and 60 mg Toreforant, respectively. The posterior probabilities of 30 and 60 mg Toreforant inducing a greater response rate than placebo were 97.4% and 90.3%, respectively; neither met the 97.5% predefined success criterion. Results for the IGA 0/1 endpoint were similar. Toreforant was generally safe and well tolerated. No deaths, serious or opportunistic infections, active tuberculosis, or malignancies were reported.Toreforant efficacy at 30 and 60 mg was greater than placebo but did not meet predefined success criterion. J Drugs Dermatol. 2018;17(8):873-879.

Histamine receptor H4 (HRH4) is one of four known histamine receptors, among which H1 receptor is primarily involved in typeI allergic reactions and H2 receptor is generally recognized for its role in gastric acid secretion. Compared with H1 and H2, HRH4 has unique characteristics; it is expressed in neurons and vascular endothelial cells, and is reported to be deeply involved in inflammation. Therefore, we investigated whether HRH4 is expressed in choroidal neovascularization(CNV), the main cause of age-related macular degeneration, and further examined whether HRH4-targeted treatment is effective in suppressing CNV. It was determined that HRH4 was expressed in human and mouse CNV, but not in the normal state of mouse retina, retinal pigment epithelium, or choroid. Laser-induced CNV in Hrh4-deficient mice was significantly smaller compared with that in wild-type mice. Immunohistochemistry showed co-positivity of the macrophage marker F4/80 with HRH4-positive cells in laser-induced CNV. Intravitreal administration of an HRH4 antagonist reduced laser-induced CNV in wild-type mice. In addition, oral administration of an HRH4 antagonist also reduced laser-induced CNV. HRH4 antagonists had no effect on tube formation in human retinal vascular endothelial cells. We also examined retinal toxicity after HRH4 antagonist administration; no retinal degeneration was observed even when a large amount of HRH4 antagonist was injected into the mouse eyes, which was confirmed using fundus imaging, retinal histology, and electroretinography. In conclusion, HRH4 antagonist is believed to be a possible therapeutic agent that reduces CNV without causing retinal toxicity.

Atopic dermatitis (AD) and psoriasis are common skin diseases with a high negative impact on patients' quality of life. Both diseases are mediated by a pro‐inflammatory infiltrate consisting of several cell types, such as T‐cells, antigen‐presenting cells and granulocytes and display disturbed keratinocyte differentiation. Given the fact that histamine levels are also highly elevated in inflamed skin, it is likely that histamine plays a relevant role in disease pathology. However, antagonists blocking histamine H(1) receptor or H(2) receptors are largely ineffective in reducing chronic symptoms in AD and psoriasis. Over the last years, much research has been undertaken to shed light into the mode of action of the most recently discovered histamine H(4) receptor. This research has shown that H(4) receptor antagonists display antipruritic and anti‐inflammatory effects not only in mouse models but also in first human clinical trials, and therefore, H(4) receptors might present a novel therapeutic target. In this review, we summarize the effects of the H(4) receptors on different cell types, mouse models and clinical studies in regard to AD and psoriasis respectively. 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

Data from preclinical and clinical studies support the evaluation of histamine 4 receptor antagonists in the treatment of asthma. Toreforant is a selective histamine 4 receptor antagonist that could be effective in patients with eosinophilic asthma.To evaluate the efficacy and safety of toreforant in patients with eosinophilic, persistent asthma that was inadequately controlled despite current treatment.In this phase 2a, multicenter, randomized, double-blinded, parallel-group, placebo-controlled, proof-of-concept study, 162 eligible patients were randomized (1:1) to placebo or 30 mg of toreforant once daily through week 24 and followed for 4 weeks. The primary end point was change from baseline in pre-bronchodilator percent-predicted forced expiratory volume in 1 second at week 16. Secondary end points included change from baseline at week 16 in postbronchodilator percent-predicted forced expiratory volume in 1 second, Asthma Control Questionnaire scores, weekly averages of Daytime and Nighttime Asthma Diary Symptom Scores, and weekly average of number of puffs in a day that rescue medication was used.There was no significant difference between groups in pre-bronchodilator percent-predicted forced expiratory volume in 1 second at week 16 (difference in least-square means -0.19%; 95% confidence interval -3.01 to 2.64; P = .90). Similarly, there were no significant differences between groups at week 16 in changes from baseline in the secondary end points (P ≥ .30). Toreforant was generally well tolerated. No deaths or serious adverse events were reported at any time point.Toreforant, at the dose tested, failed to provide therapeutic benefit in this population of patients with uncontrolled, eosinophilic, persistent asthma.ClinicalTrials.gov, NCT01823016.

Microglia, the resident immune cells of the central nervous system (CNS), are activated at the beginning of the inflammatory response and induce detrimental neuroinflammation by producing excessive pro-inflammatory cytokines. Nuclear factor kappa B (NF-κB) signaling facilitates the onset of microglia activation. However, the molecular mechanisms underlying the negative regulation of NF-κB remain to be fully elucidated. In the present study, our results indicated that H4R expression increased in a rat model of lipopolysaccharide (LPS)-induced CNS inflammation. Knockdown of H4R in microglia HAPI cells enhanced the production of cytokines following LPS stimulation. Co-immunoprecipitation experiments further revealed an interaction between H4R and tumor necrosis factor receptor-associated factor 6 (TRAF6) in microglia, which was verified both in vivo and in vitro. Our experimental results support our hypothesis that H4R interacts with TRAF6 to inhibit the release of inflammatory cytokines in LPS-induced microglia cells by decreasing TRAF6-mediated ubiquitination of K63. These findings provide theoretical and experimental evidence regarding the role of H4R in the microglia inflammatory response, which may aid in the development of novel treatments for inflammation.

Receptor-binding affinity and ligand-receptor residence time are key parameters for the selection of drug candidates and are routinely determined using radioligand competition-binding assays. Recently, a novel bioluminescence resonance energy transfer (BRET) method utilizing a NanoLuc-fused receptor was introduced to detect fluorescent ligand binding. Moreover, this NanoBRET method gives the opportunity to follow fluorescent ligand binding on intact cells in real time, and therefore, results might better reflect in vivo conditions as compared with the routinely used cell homogenates or purified membrane fractions. In this study, a real-time NanoBRET-based binding assay was established and validated to detect binding of unlabeled ligands to the histamine H

The anti-inflammatory effects of histamine H4 receptor (H4R) antagonists opened new therapeutic options for the treatment of inflammatory/allergic diseases, but the role of H4R in inflammation is far from being solved. Aim of the present study was to investigate the role of structurally related H4R ligands of the aminopyrimidine class with different efficacies and functionalities (neutral antagonist ST-994, partial agonist ST-1006, inverse agonist ST-1012, and partial inverse agonist ST-1124) on croton oil-induced ear edema and pruritus in mice. The H4R ligands were administered subcutaneously before topical application of croton oil. While ST-1006 and ST-1124 were ineffective at any dose tested (10-100 mg/kg), both ST-994 and ST-1012 (30 and 100 mg/kg) significantly reduced croton oil-induced ear edema. Moreover, ST-994, ST-1006, and ST-1124, but not ST-1012, significantly inhibited croton oil-induced ear pruritus at 30 mg/kg. In accordance with results obtained with the reference H4R antagonist JNJ7777120 (100 mg/kg), histological examination of inflamed ear tissue indicated that treatment with ST-994 (30 mg/kg) led to a significant reduction in the inflammatory severity score and in the number of eosinophils infiltrating the tissue, while the number of degranulated mast cells in inflamed tissues was increased in comparison with the number of intact mast cells. These data indicate that croton oil-induced ear inflammation and pruritus seem to be clearly, but variably, affected by the H4R ligands tested. The potential advantage of dual effect of the H4R neutral antagonist ST-994 has to be carefully considered as a new therapeutic approach to the treatment of inflammatory diseases.

The diverse effects of histamine are mediated by discrete histamine receptors. The principal repository of histamine in the body is the mast cell. However, the effects of histamine on mast cells, especially those of human origin, have not been fully elucidated. In this study, the expression of histamine receptors in human lung mast cells was evaluated. Moreover, the effects of histamine receptor engagement on both mediator release and chemotaxis were investigated. Mast cells were isolated and purified from human lung tissue. Histamine receptor expression was determined by RT-PCR and q-PCR. Both methods for the detection of histamine receptors were in accordance and human lung mast cells expressed mRNA for histamine H

Contains fulltext : 214997.pdf (Publisher’s version ) (Closed access) The activation of microglial cells is presumed to play a key role in the pathogenesis of Parkinson's disease (PD). The activity of microglia is regulated by the histamine-4 receptor (H4R), thus providing a novel target that may prevent the progression of PD. However, this putative mechanism has so far not been validated. In our previous study, we found that mRNA expression of H4R was upregulated in PD patients. In the present study, we validated this possible mechanism using the rotenone-induced PD rat model, in which mRNA expression levels of H4R-, and microglial markers were significantly increased in the ventral midbrain. Inhibition of H4R in rotenone-induced PD rat model by infusion of the specific H4R antagonist JNJ7777120 into the lateral ventricle resulted in blockade of microglial activation. In addition, pharmacological targeting of H4R in rotenone-lesioned rats resulted in reduced apomorphine-induced rotational behaviour, prevention of dopaminergic neuron degeneration and associated decreases in striatal dopamine levels. These changes were accompanied by a reduction of Lewy body-like neuropathology. Our results provide first proof of the efficacy of an H4R antagonist in a commonly used PD rat model, and proposes the H4R as a promising target to clinically tackle microglial activation and thereby the progression of PD. 01 februari 2019

Histamine induces chemotaxis of mast cells through the H

Hemorrhagic shock has a potential to be life-threatening when it is not treated. The main causes of hemorrhagic shock involve: (1) forces causing injury; and (2) diseases that can cause hemorrhage., Therefore, due to the causes of hemorrhagic shock and the life-threatening potential, the search for new methods of shock treatment is extremely valuable to the modern medicine. The aim of this study was to investigate the influence of clobenpropit in the model of hemorrhagic shock. The experiments were conducted in 110 adult male Wistar rats weighing between 205 and 470g. 1, 2 and 5 μmol/kg of intravenous H3 receptors reverse agonists, clobentropit, and/or 1, 5 and 10 μmol/kg H3 receptor agonist, imetit, were used as general anesthetics. Irreversible hemorrhagic shock was induced by the paused bleeding until the mean arterial pressure (MAP) lowered to the level of 20-25 mmHg. It was proved that, in cases of critical hypotension, clobenpropit triggered a dose-dependent increase of: systolic blood pressure (SBP), diastolic blood pressure (DBP), MPA and heart rate (HR) of rats with critical hypotension. The most significant changes in hemodynamic parameters were achieved by administrating dosages of 2 mmol/kg. This resulted in the survival rate increase to up to 100%. However, imetit did not trigger any hemodynamic changes nor an increase in SBP, DBP, MAP or HR. Furthermore, it was found that the premedication with prazosin, yohimbine, 6-hydroxydopamine and the vasopressin V1a receptor antagonist blocked the effects of clobenpropit. Additionally, premedication with propranolol, captopril and ZD 7155 did not cause any significant changes in the measured hemodynamic parameters. In conclusion, after an intravenous injection clobenpropit, the inverse agonist of H3 histamine receptors/agonist of histamine receptors H4, causes a resuscitating effect on rats in hemorrhagic shock. Moreover, such effect is based on the effector mechanisms of sympathetic nervous system and vasopressin.