Background/Aims: Interleukin-17 (IL-17) is a major pro-inflammatory cytokine that initiates and maintains inflammation. However, the molecular mechanisms as to how IL-17 influences endothelial cells to promote neutrophil recruitment are not fully understood. Methods: Human endothelial cells (HMECs) were stimulated with IL-17, and investigated for proliferation, migration, and tubule formation activities. Transwell chemotaxis and adhesion assays were performed to assess neutrophil recruitment. Cytokine production was measured by Cytokine Array Chip and ELISA. Western blotting and immunofluorescent analysis were used to detect the phosphorylation and translocation of STAT3. Specific inhibitors, small interfering RNA, and phosphorylation mutants were used to confirm that IL-17 induced STAT3 activation via IL-17RA signaling. Results: Activation of HMECs with IL-17 induced STAT3 phosphorylation and nuclear translocation, which were associated with induction of GRO-α, GM-CSF and IL-8, and neutrophil recruitment. Phosphorylation of STAT3 was identified mainly at the tyrosine in position 705 (Y705), and the Y705F mutants attenuated IL-17-mediated STAT3 activation. Moreover, specific inhibitors, FLLL31, or siRNA silencing of STAT3 attenuated HMECs activation, resulting in inhibition of GRO-α, GM-CSF, IL-8 production, and neutrophil recruitment. Furthermore, phosphorylation of STAT3 was identified as downstream of IL-17RA signaling. Conclusions: IL-17 induced STAT3 activation as a necessary step in endothelial cell activation and neutrophil recruitment.

Brusatol, a biologically active natural product, was modified in four distinct positions through the covalent attachment of a furoxan moiety, which acts as a nitric oxide (NO) donor. Forty derivatives were synthesized and evaluated for their inhibitory effects on excess NO biosynthesis in activated macrophages. Among them, compound 75 demonstrated inhibition (IC50 = 0.067 μM) comparable to that of brusatol but were less cytotoxic. More importantly, even at very low doses (2 μmol/kg/day), compound 75 also showed substantial inhibitory efficacy against chronic obstructive pulmonary disease (COPD)-like inflammation in the mouse model induced by cigarette smoke (CS) and lipopolysaccharide (LPS). Particularly, this compound was over 100-fold less toxic (LD50 > 3852 μmol/kg) than brusatol and could be a promising lead for further studies. Notably, the improved properties of this derivative are associated with its NO-releasing capability.

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Twelve hydrolyzable tannins were obtained from the twigs of Myricaria bracteata, including two new hellinoyl-type dimers, bracteatinins D1 (1) and D2 (2); a new hellinoyl-type trimer, bracteatinin T1 (3); two known monomers, nilotinin M4 (4) and 1,3-di-O-galloyl-4,6-O-(aS)-hexahydroxydiphenoyl-β-d-glucose (5); six known dimers, tamarixinin A (6), nilotinin D8 (7), hirtellins A (10), B (9), and E (8), and isohirtellin C (11); and a known trimer, hirtellin T3 (12). The structures of the tannins were elucidated by spectroscopic data analysis and comparisons to known tannins. All compounds were evaluated as free radical scavengers using 1,1-diphenyl-2-picrylhydrazyl and hydroxy radicals and compared to the activity of BHT and Trolox. Compound 6 showed a significant anti-inflammatory effect on croton oil-induced ear edema in mice (200 mg/kg, inhibition rate 69.8%) and on collagen-induced arthritis in DBA/1 mice (20 mg/kg, inhibition rate 46.0% at day 57).

Vam3 protects bronchial epithelial cells from CS-induced apoptosis in vitro and in vivo by preventing mitochondrial dysfunction.