4-Methylhistamine (hydrochloride)

4-Methylhistamine is a histamine H4 receptor agonist (Ki = 50 nM).{36324} It is >100-fold selective for H4 over other histamine receptors. 4-Methylhistamine inhibits CRE-B-galactosidase activity induced by forskolin (Item No. 11018) with an EC50 value of 39.8 nM in SK-N-MC cells transfected with the human H4 receptor. It induces a change in eosinophil shape (EC50 = 0.36 ?M) and stimulates migration of murine bone marrow mast cells (EC50 = 12 ?M), activities that can be inhibited by the histamine H4 antagonist JNJ-7777120 (Item No. 10011925). Intratracheal administration of 4-methylhistamine (10 ?g/animal) reduces airway resistance and inflammation and increases the number of CD4+CD25+FoxP3+ regulatory T cells in a mouse model of allergic asthma.{36323} 4-Methylhistamine also reduces epidermal hyperplasis, hyperkeratosis, and lymphocyte infiltration and increases the number of CD4+CD25+FoxP3+ regulatory T cells in a mouse model of psoriasis induced by imiquimod (Item No. 14956).{36325}