Our previous studies showed that the anti-inflammatory effects of Paeonia lactiflora roots extract may be mediated, at least in part, through its gallic acid content, and this effect may be regulated in part by an inhibition on cAMP-phosphodiesterase (PDE). To explore the anti-inflammatory effect and mechanism, the influence of gallic acid on neutrophils PDE4 activity and expression, TNF-α and IL-6 content and rat arthritis model were further studied. PDE4 activity and gene express were calculated respectively by substrate cAMP change examined with HPLC and real-time RT-PCR. The concentration of IL-6 and TNF-α in supernatant were assayed by ELISA method. Model of rat arthritis was caused by complete Freund’s adjuvant. Results showed that gallic acid had a dose-dependent restraint on PDE4 activity of neutrophils in vitro, promoted significantly PDE4A expression (P<0.01), and had no influence on the expressions of PDE4B and 4D. However, PDE4C expression was not detected. Gallic acid could promote IL-6 release (P<0.05), and inhibit TNF-α release of neutrophils (P<0.05). The experiment in vivo showed that gallic acid had obvious restraint on local inflammation of animal model (P<0.05). Therefore, the anti-inflammatory effect of gallic acid may be mediated in part through an inhibition on PDE4 activity and further an increase of IL-6 and a decrease of TNF-α of neutrophils, and this effect seemed to have no relationship with PDE4 expression.

Luteolin is an active ingredient found early from Folium perillae and Flos lonicerae, and has a specific inhibition on phosphodiesterase 4 (PDE4) activity in vitro. Researches show luteolin has pharmacological effects of anti-inflammation, anti-anaphylaxis, antitumor, antioxidant, protection of nervous system and so on, and has mainly been used for the treatment of respiratory inflammatory diseases, cancer and cardiovascular disease in clinic. PDE4, specific to hydrolyze cyclic AMP (cAMP), is considered to be a new anti-inflammatory target due to the decisive role on cAMP signal in inflammatory cells such as neutrophils. In order to explore the anti-inflammatory mechanism, we further studied the effects of luteolin on the activity and expression of PDE4, the expression of lymphocyte function-associated antigen-1 (LFA-1) and macrophage-1 (MAC-1) in neutrophils, and the adhesion of neutrophils and endothelial cells. The results showed that luteolin had a dose-dependent inhibition on both bare PDE4 activity and PDE4 in cultured neutrophils, and had an obviously promotive effect on gene expressions of PDE4A, 4B and 4D in later period. Luteolin had a significant inhibitory effect on neutrophils adhesion and LFA-1 expression in early stage, and had no obvious effect on MAC-1 expression. Therefore, luteolin can inhibit LFA-1 expression of neutrophils, then inhibit the adhesion of neutrophils and endothelial cells, and the mechanism is at least related with the inhibition of PDE4 activity.

Pulsatilla decoction is a famous traditional Chinese herbal formula for clearing heat and treating dysentery of animals or human. To elucidate its mechanism, many active components have been studied, however, the roles of its polysaccharides still remain unclear. This study aimed to explore effects of polysaccharides from Pulsatilla decoction (PPD) on the microvascular endothelial glycocalyx (eGC). The polysaccharides were extracted from PPD by water extraction and alcohol precipitation method. Mice were administered with PPD for 4 wk, and were then anesthetized with ether inhalation and were fixed by cardiac perfusion with gradient concentration alcian blue solution. The jejunum was sampled and jejunal mucosa was prepared for ultrathin sections by routine method and was analyzed by transmission electron microscope. The results indicated that the eGC was observed as a strong electron-dense smooth linear margin or nonuniform conglomerates coating cell membranes, and PPD significantly increased its thickness from (21.85±1.87) to (28.71±3.61) nm and improved its integrity. This study suggested that PPD may express their biological activities and protect against pathogenic factor damages by influencing the eGC.

We studied the effect of baicalin, an extract from Radix Scutellariae (a traditional Chinese medicine) in inducing mouse pulmonary microvascular endothelial cells (MPMVECs) to produce interferons (IFNs). MPMVECs were cultured in vitro in the presence of different concentrations of baicalin (10, 20, and 30 μg mL-1), and the cells and the culture media were harvested at various time intervals. The proteins and mRNA levels (relative to β-actin) of IFN-α/β and IFN-γ were analyzed by RT-PCR and enzyme-linked immunosorbent assay (ELISA). It was observed that baicalin substantially up-regulated the expression of IFN-α/β and IFN-γ. In all baicalin-treated groups, the relative levels of IFN-α/β and IFN-γ mRNAs peaked after 12 h of culturing, and IFN-α/β and IFN-γ proteins peaked after 24 h of culturing. These results suggest that baicalin can effectively induce the expression of IFNs in pulmonary microvascular endothelial cells, and thus potentially act as an antiviral compound. This study may provide background information for developing new antiviral drugs based on baicalin.