Yukio Azuma

Pharmacological Studies on the Anti-inflammatory Action of Phenolic Compounds:

The mechanism of the anti-inflammatory action of phenolic compounds was examined using neutrophil chemotaxis. Chemotactic activity of guinea pig peritoneal neutrophils to N-formylmethionyl-leucylphenylalanine (FMLP) was suppressed in a concentration-dependent manner. The order of drug potency in inhibiting the neutrophil chemotaxis was eugenol » thymol > guaiacol » phenol. The concentrations of phenolic compounds used in these experiments did not induce lactate dehydrogenase (LDH) release and did not affect neutrophil viability. There was a consistent positive relation between the ID50 of superoxide anion generation in neutrophils and the inhibitory dose for neutrophil chemotaxis by phenolic compounds. A free phenolic hydroxyl group is essential for scavenging oxygen free-radicals and is also essential for inhibiting leukocyte chemotaxis, as was demonstrated in these experiments. These findings suggest that inhibition of leukocyte chemotaxis may be involved in the anti-inflammatory action of phenolic compounds, and that one of the anti-inflammatory actions of phenolic compounds is the prevention of the production of oxygen free-radicals by leukocytes.

The growth factor progranulin attenuates neuronal injury induced by cerebral ischemia-reperfusion through the suppression of neutrophil recruitment.

BackgroundTo improve the clinical outcome of patients who suffered ischemic stroke, cerebral ischemia-reperfusion (I/R) injury is one of the major concerns that should be conquered. Inflammatory reactions are considered a major contributor to brain injury following cerebral ischemia, and I/R exacerbates these reactions. The aim of this study was to investigate the possible ameliorative effects of progranulin (PGRN) against I/R injury in mice.MethodsIn vivo I/R was induced in four-week-old male ddY mice by 2 h of MCAO (middle cerebral artery occlusion) followed by 22 h of reperfusion. We evaluate expression of PGRN in I/R brain, efficacy of recombinant-PGRN (r-PGRN) treatment and its therapeutic time-window on I/R injury. Two hours after MCAO, 1.0 ng of r-PRGN or PBS was administered via intracerebroventricular. We assess neutrophil infiltration, expression of tumor necrosis factor (TNF)-α, matrix metalloproteinase-9 (MMP-9) and phosphorylation of nuclear factor-κB (NF-κB) by immunofluorescense staining and Western blotting. We also investigate neutrophil chemotaxis and intercellular adhesion molecule-1 (ICAM-1) expression in vitro inflammation models using isolated neutrophils and endothelial cells.ResultsWe found that expression of PGRN was decreased in the I/R mouse brain. r-PGRN treatment at 2 h after MCAO resulted in a reduction in the infarct volume and decreased brain swelling; this led to an improvement in neurological scores and to a reduction of mortality rate at 24 h and 7 d after MCAO, respectively. Immunohistochemistry, Western blotting, and gelatin zymography also confirmed that r-PGRN treatment suppressed neutrophil recruitment into the I/R brain, and this led to a reduction of NF-κB and MMP-9 activation. In the in vitro inflammation models, PGRN suppressed both the neutrophil chemotaxis and ICAM-1 expression caused by TNF-α in endothelial cells.ConclusionsPGRN exerted ameliorative effects against I/R-induced inflammation, and these effects may be due to the inhibition of neutrophil recruitment into the I/R brain.

Mesenchymal miR-21 regulates branching morphogenesis in murine submandibular gland in vitro

Branching morphogenesis in murine submandibular glands (SMG) is regulated by growth factors, extracellular matrix (ECM) and many biological processes through interactions between the epithelium and the mesenchyme. MicroRNAs (miRNAs) are a set of small, non-protein-coding RNAs that regulate gene expression at the post-transcriptional level. We hypothesized that branching morphogenesis is partly regulated by miRNAs. Forty-four miRNAs and novel miRNA candidates were detected in SMG at embryonic day 13 by a cloning method combined with Argonaute-2 immunoprecipitation. MicroRNA21 (miR-21) expression in the mesenchyme was up-regulated and accelerated by epidermal growth factor, which is known to enhance branching morphogenesis in vitro. Down-regulation of miR-21 in the mesenchyme by locked nucleic acids was associated with a decrease in the number of epithelial buds. Relative quantification of candidates for target genes of miR-21 indicated that two messenger RNAs (for Reck and Pdcd4) were down-regulated in the mesenchyme, where miR-21 expression levels were up-regulated. These results suggest that branching morphogenesis is regulated by miR-21 through gene expression related to ECM degradation in the mesenchyme.