1. Histamine induces proliferation in keratinocytes from patients with atopic dermatitis through the histamine 4 receptor 
Franziska Glatzer, PhD, Maria Gschwandtner, PhD, Sarah Ehling, DVM, Kristine Rossbach, DVM, Katrin Janik, PhD, Andreas Klos, MD, Wolfgang Bäumer, DVM, Manfred Kietzmann, DVM, Thomas Werfel, MD, Ralf Gutzmer, MD 
Journal of Allergy and Clinical Immunology 
Volume 132, Issue 6, Pages (December 2013)
DOI: /j.jaci
Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

2. Fig 1
Histamine induces proliferation in human foreskin keratinocytes. A and B, Representative amplification products and melting peaks of 3 independent real-time PCR experiments are shown. C and D, Foreskin keratinocytes were treated with different histamine concentrations (Fig 1, C) and stimulated with histamine or H4R agonist (4-MH) for different time points (Fig 1, D). E, The H4R antagonist JNJ (JNJ) abolished the H4R agonist–induced effect. F, H1R and H2R agonists and antagonists had no influence on proliferation. Means and SEMs of 4 to 8 experiments are depicted. 2-Pyr, 2-pyridylethylamine; Amtha, amthamine; Hist, histamine; Levo, levocetirizine; NS, no stimulation; Rani, ranitidine. *P < .05 and **P < .005, paired t test.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )
Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

3. Fig 2
Histamine induces proliferation in H4R-transfected HaCaT keratinocytes. A and B, Representative amplification products and melting peaks of 5 independent real-time PCR experiments are shown. C, H4R-transfected HaCaT cells were treated with different histamine concentrations. D, Forty-eight hours of stimulation with histamine and H4R agonist (4-MH) induced proliferation of H4R-transfected HaCaT keratinocytes, as determined by using the MTT assay. E and F, The H4R antagonist JNJ abolished the H4R agonist–induced effect (Fig 2, E), whereas H1R and H2R agonists and antagonists had no influence (Fig 2, F). Means and SEMs of 6 to 12 experiments are depicted. 2-Pyr, 2-pyridylethylamine; Amtha, amthamine; Hist, histamine; Levo, levocetirizine; NS, no stimulation; Rani, ranitidine. *P < .05, **P < .005, and ∗∗∗P < .001, paired t test.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )
Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

4. Fig 3
Keratinocytes derived from patients with atopic dermatitis express high levels of H4R and respond with proliferation. A, orsKCs derived from patients with atopic dermatitis showed higher H1R and H4R levels than healthy control subjects and patients with psoriasis. B, Forty-eight hours of stimulation with histamine and H4R agonist (4-MH) induced proliferation of keratinocytes from patients with atopic dermatitis. C, The H4R antagonist JNJ (JNJ) abolished the H4R agonist–induced effect in keratinocytes from patients with atopic dermatitis. Medians and quartiles of 6 to 8 experiments are depicted. Hist, Histamine; NS, no stimulation. The Mann-Whitney test was used for statistical analysis in Fig 3, A, and the Wilcoxon matched-pairs signed-rank test was used in Fig 3, B and C. *P < .05 and **P < .005.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )
Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

5. Fig 4
Histamine induces fast scratch wound healing in high H4R–expressing keratinocytes and H4R-transfected HaCaT cells. A and B, In keratinocytes from patients with atopic dermatitis, the scratch wound was better closed after 24 hours stimulation with histamine or the H4R agonist (4-MH) compared with nontreated control subjects. In contrast, histamine did not modify wound healing in healthy keratinocytes (Fig 4, B). C, Histamine induced faster scratch wound healing in H4R-transfected HaCaT keratinocytes but not in nontransfected or control-transfected cells. Individual values and medians of 5 to 7 experiments are depicted. eGFP, Enhanced green fluorescent protein; Hist, histamine; NS, no stimulation. *P < .05 and **P < .005, paired t test.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )
Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

6. Fig 5
H4R-deficient mice show decreased epidermal thickness, and keratinocytes derived from H4R-deficient mice have lower in vitro proliferative capacity. A, Biopsy specimens were taken from abdominal skin of wild-type and H4R-deficient mice, and epidermal thickness was measured. B, nKCs from H4R knockout and wild-type mice were cultured for 12, 24, and 48 hours, and cell proliferation was determined by using BrdU incorporation. Means and SEMs of 5 (12 hours), 6 (24 hours), and 7 (48 hours) experiments are shown. The Mann-Whitney test was used for statistical analysis. ∗∗∗P < .001.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )
Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

7. Fig 6
LPS and peptidoglycan induce expression of H4R in murine nKCs. A and B, Representative amplification products and melting peaks of 3 independent experiments are shown. C, As a control, H4R was amplified from wild-type mice spleen and dendritic cell (DC) mRNA samples, showing the same melting peak as the treated keratinocytes. PGN, Peptidoglycan; NS, no stimulation.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )
Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions