C-Type Natriuretic Peptide (CNP) Inhibition of Interferon-γ-Mediated Gene Expression in Human Endothelial Cells In Vitro.

Cardiovascular diseases, including atherosclerosis, now account for more deaths in the Western world than from any other cause. Atherosclerosis has a chronic inflammatory component involving Th1 pro-inflammatory cytokines such as IFN-γ, which is known to induce endothelial cell inflammatory responses. On the other hand CNP, which acts via its receptors to elevate intracellular cGMP, is produced by endothelium and endocardium and is upregulated in atherosclerosis. It is believed to be protective, however its role in vascular inflammation is not well understood. The aim of this study was to investigate the effects of CNP on human endothelial cell inflammatory responses following IFN-γ stimulation. Human umbilical vein endothelial cells were treated with either IFN-γ (10 ng/mL) or CNP (100 nm), or both in combination, followed by analysis by flow cytometry for expression of MHC class I and ICAM-1. IFN-γ significantly increased expression of both molecules, which was significantly inhibited by CNP or the cGMP donor 8-Bromoguanosine 3',5'-cyclic monophosphate (1 µm). CNP also reduced IFN-γ mediated kynurenine generation by the IFN-γ regulated enzyme indoleamine-2,3-deoxygenase (IDO). We conclude that CNP downmodulates IFN-γ induced pro-inflammatory gene expression in human endothelial cells via a cGMP-mediated pathway. Thus, CNP may have a protective role in vascular inflammation and novel therapeutic strategies for CVD based on upregulation of endothelial CNP expression could reduce chronic EC inflammation.

CXCL4/Platelet Factor 4 is an agonist of CCR1 and drives human monocyte migration.

Activated platelets release micromolar concentrations of the chemokine CXCL4/Platelet Factor-4. Deposition of CXCL4 onto the vascular endothelium is involved in atherosclerosis, facilitating monocyte arrest and recruitment by an as yet, unidentified receptor. Here, we demonstrate that CXCL4 drives chemotaxis of the monocytic cell line THP-1. Migration and intracellular calcium responses induced by CXCL4 were pertussis toxin-sensitive, implicating a GPCR in signal transduction. Cell treatment with chondroitinase ABC ablated migration, suggesting that cis presentation of CXCL4 by cell surface glycosaminoglycans to a GPCR is required. Although CXCR3 has been previously described as a CXCL4 receptor, THP-1 cells were unresponsive to CXCR3 ligands and CXCL4-induced migration was insensitive to a CXCR3 antagonist, suggesting that an alternative receptor is involved. Interrogating CC-class chemokine receptor transfectants, we unexpectedly found that CXCL4 could induce the migration of CCR1-expressing cells and also induce CCR1 endocytosis. Extending our findings to primary human monocytes, we observed that CXCL4 induced CCR1 endocytosis and could induce monocyte chemotaxis in a CCR1 antagonist-sensitive manner. Collectively, our data identify CCR1 as a previously elusive monocyte CXCL4 receptor and suggest that CCR1 may play a role in inflammation where the release of CXCL4 is implicated.

Mammalian Sulf1 RNA alternative splicing and its significance to tumour growth regulation.

SULF1/SULF2 enzymes regulate the activities of several growth factors by selective hydrolysis of 6-O-sulphates of heparan sulphate proteoglycan co-receptors, the sulfation of which is essential for signal transduction of some ligand/receptor interactions but not others. This study demonstrates the existence of SULF1 variants with a wide spectrum of splicing patterns in mammalian tumours. The levels and relative proportions of SULF1/SULF2 splice variants markedly vary in different tumours with a potential to regulate cell growth differentially. Although mammalian Sulf1 compared with Sulf2 gene generates a much larger number of splice variants, both enzymes follow generally similar distribution and signalling association trends in hepatocellular carcinomas.

Sulf2 gene is alternatively spliced in mammalian developing and tumour tissues with functional implications.

SULF2 enzyme regulates the activities of a number of signalling pathways that in many tissues are up-regulated during development and disease. As we recently showed for avian Sulf1, the present study demonstrates that mammalian Sulf2 gene can also generate functionally distinct splice variants that would regulate normal development and tumour growth differentially. It is thus important to distinguish SULF1/SULF2 isoforms in mammalian tissues to understand their functional and clinical relevance to disease. This study demonstrates that unlike normal adult lung with little or no SULF2 expression, this enzyme is expressed at high levels in most lung tumours showing differential cellular distribution of full length and shorter SULF2 variants in such tumours. Furthermore, we show that the short SULF2 splice variants are associated with those signalling pathways that are inhibited by full length SULF1/SULF2 variants and therefore could promote growth in such lung tumours.

Neutral endopeptidase determines the severity of pancreatitis-associated lung injury.

BACKGROUND: Neutral endopeptidase (NEP) is a cell-surface metalloprotease that degrades proinflammatory peptides such as substance P, neurokinin A, and bradykinin. Inhibition of NEP exacerbates both experimental pancreatitis and the associated lung injury. It is unclear if worsened lung injury is the indirect result of more severe pancreatitis or if it is a direct effect of NEP inhibition in the lung. MATERIALS AND METHODS: We used a model of pancreatitis-associated lung injury (PALI) to test the hypothesis that antagonism or genetic deletion of NEP augments PALI inflammation and pulmonary damage irregardless of the degree of pancreatitic inflammation. RESULTS: In NEP(+/+) mice, intraperitoneal injection of porcine pancreatic elastase (elastase, 0.085 U/g at t = 0 h and t = 1 h) caused a 7-fold increase in lung myeloperoxidase (MPO) activity and marked pulmonary edema, neutrophil infiltration, and hemorrhage at 4 h as compared to control animals. The pattern of lung injury induced by elastase mimicked that observed among a separate group of animals with PALI induced by cerulein but was not associated with pancreatitis. Both NEP(-/-) mice and NEP(+/+) mice pretreated with the NEP antagonist phosphoramidon (10 mg/kg s.c.) had significant elevations of lung MPO and worsened lung histology compared to NEP(+/+) mice given elastase alone. Antagonism of either the vanilloid receptor transient receptor vanilloid 1 or the substance P receptor NK1-R had no effect on elastase-mediated lung injury in NEP-deficient mice. CONCLUSIONS: NEP is an inhibitor of pancreatic elastase-induced lung injury, presumably via degradation of proinflammatory mediators.

Transient receptor potential vanilloid (TRPV-1) promotes neurogenic inflammation in the pancreas via activation of the neurokinin-1 receptor (NK-1R).

OBJECTIVES: The transient receptor potential vanilloid 1 (TRPV-1) is an ion channel found on primary sensory afferent neurons. Activation of TRPV-1 leads to the release of the proinflammatory neuropeptide substance P (SP). SP then binds to the neurokinin-1 receptor (NK1-R) on endothelial cells and promotes extravasation of plasma and proteins into the interstitial tissue and neutrophil infiltration, a process called neurogenic inflammation. We tested 2 hypotheses: (1) activation of TRPV-1 in the pancreas leads to interstitial edema and neutrophil infiltration and (2) TRPV-1-induced plasma extravasation is mediated by the release of SP and activation of the NK1-R in the rat. METHODS: We measured extravasation of the intravascular tracer Evans blue as an index of plasma extravasation and quantified pancreas tissue myeloperoxidase activity (MPO) as a marker of neutrophil infiltration. The severity of inflammation following intravenous infusion of the secretagogue cerulein (10 microg/kg/h x 4 hours) was assessed using a histologic scoring system. RESULTS: Intravenous injection of the TRPV-1 agonist capsaicin induced a dose-dependent increase in Evans blue accumulation in the rat pancreas (P < 0.05 vs. vehicle control). This effect was blocked by pretreatment with the TRPV-1 antagonist capsazepine (1.8 mg/kg), or the NK1-R antagonist CP 96,345 (1 mg/kg). Capsazepine also reduced cerulein-induced Evans blue, MPO, and histologic severity of inflammation in the pancreas but had no effect on serum amylase. CONCLUSION: Activation of TRPV-1 induces SP-mediated plasma extravasation in the rat pancreas via activation of the NK1-R. TRPV-1 mediates neurogenic inflammation in cerulein-induced pancreatitis in the rat.

Does the DRD2-Taq1 A polymorphism influence treatment response to bupropion hydrochloride for reduction of the nicotine withdrawal syndrome?

Bupropion hydrochloride is effective in promoting long-term abstinence from smoking and may reduce risk for relapse through attenuation of withdrawal symptoms and craving. Bupropion is a weak dopamine reuptake inhibitor, and individual genetic variation in the dopamine D2 receptor has been associated with nicotine dependence in case-control studies. Thirty smokers were randomly assigned to bupropion or placebo and interviewed using the Minnesota Nicotine Withdrawal Scale on two occasions: prior to starting medication and after 14 days on bupropion or placebo. The individual symptoms of craving, irritability, and anxiety were significantly reduced in the bupropion group, whereas no withdrawal symptoms were diminished in the placebo group. Within the bupropion group, subgroup analyses with stratification by genotype demonstrated that craving, irritability, and anxiety were significantly attenuated only among subjects with DRD2-Taq1 A2/A2 genotypes. In the DRD2-Taq1 A1/A1 and A1/A2 groups, no significant reduction was seen in any individual symptom of the nicotine withdrawal syndrome. These data suggest that bupropion attenuates specific symptoms of the nicotine withdrawal syndrome and that this effect may be modified by genotype for the dopamine D2 receptor.