title: Functional characterization of histamine H4 receptor on human mast cells.
abstract: Among the four different types of histamine receptors (H1-H4), H4R is predominantly expressed in immune cells and involved in immunomodulatory response. Here, in this study we determined the expression of H4R in human mast cells (HMC-1, LAD-2 and primary cord blood derived CD34+ human mast cells) and characterized its functional properties. Interestingly, we found that human mast cells responded to both histamine (natural ligand) and 4-methylhistamine (selective H4R agonist) for sustained intracellular calcium mobilization, degranulation and cytokine production. However, only histamine induced the release of cAMP, but 4-methylhistamine down regulates cAMP indicating that H4R mediates its effect through Gαi/o protein and H1R via Gαq protein. Furthermore, both histamine and 4-methylhistamine induced the production of cysteinyl leukotrienes and LTB4. Using human inflammation antibody array membrane, we found that H4R induced the expression of various inflammatory proteins, involving pro-inflammatory cytokines and chemokines and these are TGF-β1, TNF-α, TNF-β, PDGF-BB, TIMP-2, M-CSF, IP-10, IL-16, IL-6, IL-3, IL-10, MIP-1α, IL-1α, ICAM-1, Eotaxin-2, RANTES, IL-8, MCP-1, and IL-6sR. We also quantified the level of various inflammatory cytokines produced by human mast cells through H4R. It was observed that, the production level of Th2 cytokines IL-4(401.34 pg/ml), IL-5 (64.21 pg/ml) and IL-13 (1044 pg/ml) and classical proinflammatory cytokines IL-6 (221.27 pg/ml) and IL-1β (34.24 pg/ml) and chemokines MCP-1(106 pg/ml) and IL-8 (818.32 pg/ml). Furthermore, activation of H4R caused the phosphorylation of ERK and PI3K in a time dependent manner. Taken together these data demonstrate that, the activation of H4R in human mast cells produced not only inflammatory mediators that are associated with allergic reactions but also other inflammatory conditions.
authors.affiliation: Department of Biotechnology, School of Bioengineering, SRM University, Kattankulathur 603203, Tamil Nadu, India.
authors.forename: E Angel
authors.initials: EA
authors.lastname: Jemima
authors.affiliation: Department of Pediatrics, SRM Medical College Hospital and Research Centre, Kattankulathur 603203, Tamil Nadu, India.
authors.forename: A
authors.initials: A
authors.lastname: Prema
authors.affiliation: Department of Biotechnology, School of Bioengineering, SRM University, Kattankulathur 603203, Tamil Nadu, India. Electronic address: berlathagam.e@ktr.srmuniv.ac.in.
authors.forename: E Berla
authors.initials: EB
authors.lastname: Thangam
mesh_terms: D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007107:Immune System / Q000378:metabolism; D007231:Infant, Newborn; D018836:Inflammation Mediators / Q000378:metabolism; D015289:Leukotrienes / Q000378:metabolism; D008407:Mast Cells / Q000276:immunology*; D008761:Methylhistamines / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism / Q000502:physiology*; D011968:Receptors, Histamine / Q000378:metabolism / Q000502:physiology*; D011969:Receptors, Histamine H1 / Q000235:genetics / Q000378:metabolism; D000074040:Receptors, Histamine H4; D018417:Th1 Cells / Q000378:metabolism; D018418:Th2 Cells / Q000378:metabolism
chemical_list: D016207:Cytokines; C418607:HRH4 protein, human; D018836:Inflammation Mediators; D015289:Leukotrienes; D008761:Methylhistamines; D043562:Receptors, G-Protein-Coupled; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D000074040:Receptors, Histamine H4; C025566:4-methylhistamine
keywords: 4-methylhistamine; Cytokine; Histamine; Histamine H4 receptor; Inflammatory mediators; Mast cells