Nitric oxide, derived from inducible nitric oxide synthase, decreases hypoxia inducible factor‐1α in macrophages during aspirin‐induced mesenteric inflammation

Abstract

Background and purpose: Nitric oxide (NO) modulates expression of hypoxia inducible factor-1 (HIF-1), a transcription factor regulating function of myeloid cells. Here, we have assessed the role played by NO, formed by inducible NOS (iNOS), in the inflammation induced by aspirin in the gut, by modulating HIF-1 activity. Experimental approach: The role of iNOS-derived NO on leucocyte-endothelial interactions induced by aspirin was evaluated by intravital microscopy in mesenteric venules of rats pretreated with selective iNOS inhibitors, 1400W or L-N6-(1-iminoethyl)-lysine. NO was localized by fluorescence microscopy, using DAF-FM. iNOS, HIF-1a and CD36 were localized by immunohistochemistry. Key results: Leucocyte-endothelial interactions increased at 6 h and returned to normal levels 24 h after aspirin administration. Numbers of migrated leucocytes were similar between 6 and 24 h after aspirin. iNOS expression and iNOS-derived NO synthesis were observed in leucocytes of the mesentery of aspirin-treated rats. Blockade of iNOS activity in aspirin-treated rats: (i) did not modify leucocyte infiltration at 6 h, but reduced the number of polymorphonuclear leucocyte and increased that of macrophages at 24 h; (ii) increased HIF-1a immunostaining in macrophages of the mesentery; and (iii) prevented the decrease in CD36 immunostaining induced by aspirin in these cells. Conclusions and implications: NO, associated with acute gut inflammation induced by aspirin, diminished HIF-1a stabilization in macrophages. Early inhibition of iNOS-derived NO synthesis, by increasing the activity of HIF-1 in these cells, may accelerate the clearance of leucocytes.

Nitric Oxide Donor-Based Cancer Therapy: Advances and Prospects

“…Accordingly, NO donors reduce the stabilization of HIF-1α in cancer cells, leading to increased tumor blood flow and oxygenation. 58,59 GTN has been clinically demonstrated as a promising chemosensitizing agent, and the most commonly performed clinical trials of GTN are against advanced non-small-cell lung cancers (NSCLCs), which are usually associated with poor chemotherapy outcomes due to tumor hypoxia. 60 In a randomized phase II clinical trial in 120 Asian NSCLC patients at stage IIIB/IV in 2006, transdermally applied GTN (25 mg/ patient daily for 5 days) plus vinorelbine (25 mg/m 2 on days 1 and 8)/cisplatin (80 mg/m 2 on day 1) (Figure 4) led to an improved time to progress (TTP) value compared with vinorelbine/cisplatin alone (327 vs 185 days).…”

“…NO donors usually act as sensitizing agents against chemo- or radioresistant cancer cells, which are commonly characterized by hypoxia and the expression of high levels of HIF-1α. Accordingly, NO donors reduce the stabilization of HIF-1α in cancer cells, leading to increased tumor blood flow and oxygenation. , …”

New Laboratory Protocol to Determine the Oxidative Stress Profile of Human Nasal Epithelial Cells Using Flow Cytometry

“…Peroxynitrite (ONOO − ) production was assessed using DHR1,2,3, an uncharged, nonfluorescent ROS indicator that passively diffuses across membranes where it is oxidised to cationic rhodamine 123, exhibiting green fluorescence [ 29 , 30 ]. Nitric oxide (NO) production was assessed using DAF-FM DA, an otherwise nonfluorescent probe that forms a fluorescent benzotriazole when it reacts with NO, thereby acting as a specific NO detector [ 31 , 32 ]. Intracellular thiol-reduced status, including reduced glutathione (GSH), was measured using CMFDA [ 33 , 34 ].…”

Real‐time cytometric assay of nitric oxide and superoxide interaction in peripheral blood monocytes: A no‐wash, no‐lyse kinetic method

“…Dihydroethidium (HE) and propidium iodide (PI) were purchased from Sigma. DAF‐FM DA is a cell‐permeable fluorogenic substrate that is used to detect and quantify intracellular NO . DHR123 is an uncharged and nonfluorescent substrate indicator that diffuses passively across membranes where it is oxidized to cationic rhodamine 123, which localizes in the mitochondria and exhibits green fluorescence.…”