New Potential of Roxatidine Acetate Hydrochloride on Atopic Dermatitis Mouse Model, Human Keratinocytes, and Human Skin Equivalent Model

The mRNA expression and secretion of granzyme B are up-regulated via the histamine H2 receptor in human CD4+ T cells

INTRODUCTION

Granzyme B (GZMB), a serine protease with cytotoxic and immunomodulatory functions, shows elevated levels in blood plasma of patients with atopic dermatitis (AD). It has been observed that GZMB expression in CD4+ and CD8+ T cells is higher in lesional skin in AD than in healthy skin. Since histamine is present in high concentration in the skin of AD patients, we investigated the regulation of GZMB in human CD4+ T cells by histamine.

METHODS

Naïve CD4+ T cells polarized into Th2 cells, total CD4+ T cells treated with IL-4 for 72 h and CD4+ T cells isolated from healthy donors and AD patients were investigated. The cells were stimulated with histamine or with different histamine-receptor agonists. Gene expression was evaluated by RNA-Seq. GZMB mRNA expression was detected by quantitative real time PCR, whereas GZMB secretion was measured by ELISpot and ELISA. T cell degranulation was evaluated by flow cytometry using CD107a surface expression as a degranulation marker.

RESULTS

By RNA-Seq, we identified the up-regulation of various genes of the cytotoxic pathway, in particular of GZMB, by histamine in Th2-polarized CD4+ T cells. In Th2-polarized CD4+ T cells and in CD4+ T cells activated by IL-4 the mRNA expression of GZMB was significantly up-regulated by histamine and by histamine H2 receptor (H2R) agonists. The induction of GZMB secretion by histamine was significantly higher in CD4+ T cells from AD patients than in those from healthy donors. CD107a surface expression was up-regulated by trend in response to histamine in Th2-polarized CD4+ T cells.

CONCLUSION

Our findings may help to elucidate novel mechanisms of the H2R and to achieve a better understanding of the role of GZMB in the pathogenesis of AD.

Effects of Echinocystic Acid on Atopic Dermatitis and Allergic Inflammation of the Skin and Lungs

BACKGROUND

Echinocystic acid (ECA), a pentacyclic triterpene enriched in various herbs, promotes anti-inflammatory and antioxidant activity; however, its therapeutic effects on atopic dermatitis (AD) or atopic march and the underlying mechanisms of action have not yet been fully elucidated.

PURPOSE

This study aimed to elucidate the effects and molecular mechanisms of ECA on AD and allergic inflammation.

METHODS

We evaluated the inhibitory effects of ECA using a house dust mite (HDM)-induced AD mouse model and human keratinocytes.

RESULTS

The results revealed that ECA improved AD symptoms by decreasing epidermal/dermal thickness, immune cell infiltration, and restoring skin barrier function, as well as an imbalanced immune response. In addition, repeated epicutaneous HDM challenges aggravated allergic inflammation in mice lungs, which was caused by the infiltration of immune cells and collagen deposition, whereas ECA alleviated these symptoms. Moreover, ECA suppressed the expression of T helper cell-derived cytokines, phosphorylation of extracellular signal-regulated kinase, and signal transducer and activator of transcription 1 in the skin and lungs of mice with HDM-induced AD, as well as inhibited the translocation of nuclear factor-κB in HaCaT keratinocytes.

CONCLUSION

This is the meaningful study to demonstrate that ECA improves allergic inflammation of the skin and lungs through recovery of the skin barrier, regulation of immune balance, and alleviation of lung inflammation, suggesting that ECA has therapeutic potential as an antiatopic and antiallergic agent that blocks the progression of AD to atopic march.