Histamine differentially regulates the production of Th1 and Th2 chemokines by keratinocytes through histamine H1 receptor.

Histamine is a biological amine that plays an important role in allergic responses. However, the involvement of histamine signaling in late allergic responses in the skin is poorly understood. Therefore, we attempted to investigate the involvement of histamine signaling in late allergic responses, especially in keratinocytes (KCs). HaCaT KCs and normal human KCs (NHKs) predominantly expressed histamine H1 receptor (H1R) and H2 receptor (H2R). Histamine suppressed tumor necrosis factor α (TNF-α)- and interferon-γ (IFN-γ)-induced production of CC chemokine ligand 17(CCL17), a type 2 T-helper (Th2) chemokine, by HaCaT KCs. It suppressed the phosphorylation of p38 mitogen-activated protein (MAP) kinase, but not that of extracellular signal-regulated kinases (ERKs), and TNF-α- and IFN-γ-induced nuclear factor κB (NFκB) activity. In contrast, histamine enhanced the production of CXC chemokine ligand 10 (CXCL10), a Th1 chemokine, by TNF-α- and IFN-γ-stimulated HaCaT KCs and NHKs. TNF-α- and IFN-γ-induced CXCL10 production was upregulated by suppression of p38 MAP kinase or NF-κB activity, which could explain histamine involvement. We concluded that histamine suppresses CCL17 production by KCs by suppressing p38 MAP kinase and NF-κB activity through H1R and may act as a negative-feedback signal for existing Th2-dominant inflammation by suppressing CCL17 and enhancing CXCL10 production.

Efficacy of a Moisturizer for Pruritus Accompanied With Asteatosis in Dialysis Patients: An Open-Label, Randomized, Exploratory Study.

BACKGROUND: In dialysis patients, skin disorders (dryness and itching) are frequently observed and treated with a moisturizer, in the absence of clear evidence of efficacy. STUDY DESIGN: An open-label, randomized, before/after, parallel-group, comparative/exploratory study. SETTING & PARTICIPANTS: 12 Japanese patients with chronic kidney failure undergoing maintenance hemodialysis who presented with dry skin and itching. INTERVENTION: Patients received a topical heparinoid moisturizer as the study drug for 2 weeks from the first day of the study treatment, followed by either a 2-week washout (group A: 6 participants) or further 2-week treatment (group B: 6 participants). OUTCOMES: The primary end point was change in water content in the stratum corneum in the hypochondrium. Secondary end points included change in visual analogue scale itching score and subjective evaluations of symptoms. To evaluate safety, adverse events were also investigated. MEASUREMENTS: Water content of the stratum corneum, dryness/itching improvement rating, itching visual analogue scale/duration of itching, photographic evaluation of skin symptoms, principal investigator's overall assessment of study drug, and adverse events. RESULTS: Mean water content of the stratum corneum in the combined groups significantly increased at week 2 (51.2 arbitrary units [AU] vs treatment start day, 31.6 AU; P<0.001), but significantly decreased at week 4 in group A, in which patients discontinued treatment with the study drug (39.4 AU; P = 0.005). Other efficacy end points, including the visual analogue scale itching score, were also improved by treatment with the study drug, but such improvement was not sustained after discontinuation of treatment. There were no adverse events related to the study treatment. LIMITATIONS: Only Japanese patients were included in the study, with a small sample size. CONCLUSIONS: Continuous application of the topical heparinoid moisturizer increased water content in the stratum corneum and lessened itching in dialysis patients. FUNDING: Maruho Co, Ltd. TRIAL REGISTRATION: Registered at the University Hospital Medical Information Network Clinical Trials Registry with study number UMIN000017016.

CCR4 and CCR10 are expressed on epidermal keratinocytes and are involved in cutaneous immune reaction.

CC chemokine ligand (CCL)17 and CCL27 produced by epidermal keratinocytes (KCs) recruit CC chemokine receptor (CCR)4 and CCR10 expressing T cells into the skin, respectively, resulting in enhanced skin inflammation. However, CCR4/CCL17 and CCR10/CCL27 interactions in epidermal KCs have not been investigated. The purpose of this study was to evaluate the role of the CCR4/CCL17 and CCR10/CCL27 loops in cutaneous immune reaction. Normal human KCs (NHKs) and HaCaT KCs expressed both CCR4 and CCR10 at mRNA and protein levels. CCR4 ligand CCL17 but not CCR10 ligand CCL27 induced production of IL-12 p40, granulocyte/monocyte colony-stimulating factor (GM-CSF) and nerve growth factor (NGF) by KCs. Both CCL17 and CCL27 induced migration of KCs in Boyden chamber assay and wound scratch assay. This study revealed that CCR4 and CCR10 are expressed on epidermal KCs and that both are functional in terms of skin cytokine production and/or migration to their ligand CCL17 and CCL27, respectively. Thus this study provided new insight into chemokine/chemokine receptors of KCs.