OBJECTIVETo observe the inhibitory effect of mizolastine on substance P(SP)-induced production of leukotriene B(4) (LTB(4)) and interleukin 5 (IL-5) in mouse skin.

METHODSMice were fed with different doses of mizolastine or other control drugs, 30 min after administration animals were injected intradermally with SP on the back. The treated skin samples were taken and competitive enzyme-link immunoassay (ELISA) method was applied to detect LTB (4) and IL-5 in the skin samples.

RESULTThe LTB(4) and IL-5 levels in 10 mg/kg mizolastine group were (1.23 +/-0.29)pg/ml and (34.28 +/-11.00)pg/ml, respectively, which were lower than those in saline control group [(5.52+/-1.88)pg/ml and (179.62 +/-46.25)pg/ml respectively] or loratadine group [(3.89+/-1.27)pg/ml and (127.74 +/-43.27)pg/ml respectively]. No significant difference was found between 10 mg/kg mizolastine group and dexamethasone group (P=0.161 and P=0.508).

CONCLUSIONMizolastine might inhibit the production of LTB(4) and IL-5 induced by substance P in mouse skin, suggesting that anti-inflammatory effect and the blockade of histamine H1 receptors might be involved in its anti-pruritic mechanisms.

Animals ; Benzimidazoles ; pharmacology ; Female ; Histamine H1 Antagonists ; pharmacology ; Interleukin-5 ; biosynthesis ; Leukotriene B4 ; biosynthesis ; Male ; Mice ; Mice, Inbred BALB C ; Skin ; metabolism ; Substance P ; antagonists & inhibitors

Skin exposure to low-dose ultraviolet B (UVB) light up-regulates the expression of matrix metalloproteinase-1 (MMP-1), thus contributing to premature skin aging (photo-aging). Although cyclooxygenase-2 (COX-2) and its product, prostaglandin E2 (PGE2), have been associated with UVB-induced signaling to MMP expression, very little are known about the roles of lipoxygenases and their products, especially leukotriene B4 (LTB4) and 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), in MMP-1 expression in skin keratinocytes. In the present study, we demonstrate that BLT2, a cell surface receptor for LTB4 and 12(S)-HETE, plays a critical role in UVB-mediated MMP-1 upregulation in human HaCaT keratinocytes. Moreover, our results demonstrated that BLT2-mediated MMP-1 upregulation occurs through a signaling pathway dependent on reactive oxygen species (ROS) production and the subsequent stimulation of ERK. Blockage of BLT2 via siRNA knockdown or with the BLT2-antagonist LY255283 completely abolished the up-regulated expression of MMP-1 induced by low-dose UVB irradiation. Finally, when HaCaT cells were transiently transfected with a BLT2 expression plasmid, MMP-1 expression was significantly enhanced, along with ERK phosphorylation, suggesting that BLT2 overexpression alone is sufficient for MMP-1 up-regulation. Together, our results suggest that the BLT2-ROS-ERK-linked cascade is a novel signaling mechanism for MMP-1 upregulation in low-dose UVB-irradiated keratinocytes and thus potentially contributes to photo-aging.
12-Hydroxy-5,8,10,14-eicosatetraenoic Acid/biosynthesis ; Cell Line ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Humans ; Keratinocytes/metabolism/*radiation effects ; Leukotriene B4/biosynthesis ; Matrix Metalloproteinase 1/*biosynthesis ; Phosphorylation ; Reactive Oxygen Species/metabolism ; Receptors, Leukotriene B4/*physiology ; Signal Transduction ; Ultraviolet Rays/*adverse effects

Endotoxic responses to bacterial lipopolysaccharide (LPS) are triggered by Toll-like receptor 4 (TLR4) and involve the production of inflammatory mediators, including interleukin-6 (IL-6), by macrophages. The detailed mechanism of IL-6 production by macrophages in response to LPS has remained unclear, however. We now show that LPS induces IL-6 synthesis in mouse peritoneal macrophages via the leukotriene B4 receptor BLT2. Our results suggest that TLR4-MyD88 signaling functions upstream of BLT2 and that the generation of reactive oxygen species (ROS) by NADPH oxidase 1 (Nox1) and consequent activation of the transcription factor nuclear factor (NF)-kappaB function downstream of BLT2 in this response. These results suggest that a TLR4-MyD88-BLT2-Nox1-ROS-NF-kappaB pathway contributes to the synthesis of IL-6 in LPS-stimulated mouse macrophages.
Animals ; Cell Line ; Interleukin-6/*biosynthesis ; Leukotriene B4/metabolism ; Ligands ; Lipopolysaccharides/immunology ; Macrophages/immunology/*metabolism ; Macrophages, Peritoneal/immunology/metabolism ; Mice ; Myeloid Differentiation Factor 88/*metabolism ; NADH, NADPH Oxidoreductases/metabolism ; NF-kappa B/metabolism ; Reactive Oxygen Species/metabolism ; Receptors, Leukotriene B4/*metabolism ; Signal Transduction

OBJECTIVETo explore the regularity of recipe composition by observing inhibitory effects of disassembled compositions of Mahuang decoction (MHD) on chemotaxis and leukotriene production from neutrophils in rats.

METHODNeutrophil aggregation was induced by intraperitoneal injection of glycogen in rats. Intraperitoneal lavage fluid (PLF) was collected and neu-trophils were removed. Neutrophils were stimulated by calciumionophore A23187 in vitro to produce leukotriene B4. The concentrations of leukotriene B4 was measured by reversed-phase high performance liquid chromatography(HPLC), chemotatic chamber assay was used to investigate the regulative role of MHD on chenmotaxis of the neutrophils in response to LPS stimulation.

RESULTDisassembled compositions of MHD could inhibite chemotaxis and leukotriene production from neutrophils in rats. Inhibitory effects of MHD on mast cells were different.

CONCLUSIONMHD has significantly inhibitory effects on chemotaxis and leukotriene production from neutrophils in rats. The original formula (MHD) works best. These results have confirmed the rationality and scientific level of MHD.

Animals ; Chemotaxis, Leukocyte ; drug effects ; Drug Combinations ; Drugs, Chinese Herbal ; administration & dosage ; isolation & purification ; pharmacology ; Female ; Leukotriene B4 ; biosynthesis ; Male ; Neutrophils ; drug effects ; secretion ; Plants, Medicinal ; chemistry ; Rats ; Rats, Sprague-Dawley

12(S)-Hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) is an enzymatic product of prostaglandin H2 (PGH2) derived from cyclooxygenase (COX)-mediated arachidonic acid metabolism. Despite the high level of 12-HHT present in tissues and bodily fluids, its precise function remains largely unknown. In this study, we found that 12-HHT treatment in HaCaT cells remarkably down-regulated the ultraviolet B (UVB) irradiation-induced synthesis of interleukin-6 (IL-6), a pro-inflammatory cytokine associated with cutaneous inflammation. In an approach to identify the down-stream signaling mechanism by which 12-HHT down-regulates UVB-induced IL-6 synthesis in keratinocytes, we observed that 12-HHT inhibits the UVB-stimulated activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-kappaB). In addition, we found that 12-HHT markedly up-regulates MAPK phosphatase-1 (MKP-1), a critical negative regulator of p38 MAPK. When MKP-1 was suppressed by siRNA knock-down, the 12-HHT-mediated inhibitory effects on the UVB-stimulated activation of p38 MAPK and NF-kappaB, as well as the production of IL-6, were attenuated in HaCaT cells. Taken together, our results suggest that 12-HHT exerts anti-inflammatory effect via up-regulation of MKP-1, which negatively regulates p38 MAPK and NF-kappaB, thus attenuating IL-6 production in UVB-irradiated HaCaT cells. Considering the critical role of IL-6 in cutaneous inflammation, our findings provide the basis for the application of 12-HHT as a potential anti-inflammatory therapeutic agent in UV-induced skin diseases.
Anti-Inflammatory Agents, Non-Steroidal/pharmacology ; Cell Line ; Dual Specificity Phosphatase 1/biosynthesis/genetics ; Enzyme Activation ; Fatty Acids, Unsaturated/*pharmacology ; Humans ; Interleukin-6/*biosynthesis ; Keratinocytes/*metabolism/radiation effects ; NF-kappa B/metabolism ; RNA Interference ; RNA, Small Interfering ; Receptors, Leukotriene B4/genetics ; Signal Transduction/drug effects ; Skin Diseases/drug therapy ; *Ultraviolet Rays ; Up-Regulation ; p38 Mitogen-Activated Protein Kinases/metabolism