Lung-specific RNA interference of coupling factor 6, a novel peptide, attenuates pulmonary arterial hypertension in rats.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a progressive and life-threatening disease associated with high morbidity and mortality rates. However, the exact regulatory mechanism of PAH is unknown. Although coupling factor 6 (CF6) is known to function as a repressor, its role in PAH has not been explored. Here, we investigated the involvement of endogenous CF6 in the development of PAH. METHODS: PAH was induced with monocrotaline (MCT), as demonstrated by significant increases in pulmonary artery pressure and vessel wall thickness. The adeno-associated virus (AAV) carrying CF6 short hairpin RNA (shRNA) or control vector (2×10(10) gp) was intratracheally transfected into the lungs of rats 2 weeks before or after MCT injection. RESULTS: A 2-6-fold increase in CF6 was observed in the lungs and circulation of the MCT-injected rats as confirmed by qRT-PCR and ELISA. Immunohistochemistry analysis revealed a small quantity of CF6 localized to endothelial cells (ECs) under physiological conditions spread to surrounding tissues in a paracrine manner in PAH lungs. Notably, CF6 shRNA effectively inhibited CF6 expression, abolished lung macrophage infiltration, reversed endothelial dysfunction and vascular remodeling, and ameliorated the severity of pulmonary hypertension and right ventricular dysfunction at 4 weeks both as a pretreatment and rescue intervention. In addition, the circulating and lung levels of 6-keto-PGF1a, a stable metabolite of prostacyclin, were reversed by CF6 inhibition, suggesting that the effect of CF6 inhibition may partly be mediated through prostacyclin. CONCLUSIONS: CF6 contributes to the pathogenesis of PAH, probably in association with downregulation of prostacyclin. The blockage of CF6 might be applied as a novel therapeutic approach for PAH and PA remodeling.

κ-Selenocarrageenan prevents microcystin-LR-induced hepatotoxicity in BALB/c mice.

Microcystins (MCs) are a family of cyclic heptapeptides that are produced by blooming algae Microcystis. MCs have been implicated in the development of liver cancer, necrosis and even intrahepatic bleeding. Effective prophylactic approaches and complete removal of MCs are urgently needed. Accumulating evidence suggests that microcystin-LR (MC-LR)-induced damage is accompanied by oxidative stress. Supplementation of Se can enhance resistance to oxidative stress. Therefore, in the present study, we investigated the protective effects of κ-Selenocarrageenan (Se-Car), a kind of organic Se compound, in Balb/c mice exposed to MC-LR. Our results proved that Se-Car could significantly ameliorate the hepatic damage induced by MC-LR, including serum markers of liver dysfunction, oxidative damages and histological alterations. Furthermore, Se-Car could significantly alleviate the up-regulation of the molecular targets indicating mitochondrial dysfunction and endoplasmic reticulum stress induced by MC-LR. In conclusion, Se-Car showed clear protection against toxicity induced by MC-LR. Thus, Se-Car could be useful as a new category of anti-MC-LR toxicity reagent.

Characterization of TCHQ-induced genotoxicity and mutagenesis using the pSP189 shuttle vector in mammalian cells.

Tetrachlorohydroquinone (TCHQ) is a major toxic metabolite of the widely used wood preservative, pentachlorophenol (PCP), and it has also been implicated in PCP genotoxicity. However, the underlying mechanisms of genotoxicity and mutagenesis induced by TCHQ remain unclear. In this study, we examined the genotoxicity of TCHQ by using comet assays to detect DNA breakage and formation of TCHQ-DNA adducts. Then, we further verified the levels of mutagenesis by using the pSP189 shuttle vector in A549 human lung carcinoma cells. We demonstrated that TCHQ causes significant genotoxicity by inducing DNA breakage and forming DNA adducts. Additionally, DNA sequence analysis of the TCHQ-induced mutations revealed that 85.36% were single base substitutions, 9.76% were single base insertions, and 4.88% were large fragment deletions. More than 80% of the base substitutions occurred at G:C base pairs, and the mutations were G:C to C:G, G:C to T:A or G:C to A:T transversions and transitions. The most common types of mutations in A549 cells were G:C to A:T (37.14%) and A:T to C:G transitions (14.29%) and G:C to C:G (34.29%) and G:C to T:A (11.43%) transversions. We identified hotspots at nucleotides 129, 141, and 155 in the supF gene of plasmid pSP189. These mutation hotspots accounted for 63% of all single base substitutions. We conclude that TCHQ induces sequence-specific DNA mutations at high frequencies. Therefore, the safety of using this product would be carefully examined.

Carbon nanotubes provoke inflammation by inducing the pro-inflammatory genes IL-1ß and IL-6.

Carbon nanotubes (CNTs) are largely produced and widely used because of their novel features, and the annual yield is expected to increase dramatically in the near future. Meanwhile, adverse health influences from exposure to CNTs are widely concerned, partially due to their asbestoid characteristics. In the current study, to assess the inflammatory responses and related mechanisms, we established a mouse model of chronic exposure to CNTs using intraperitoneal injection of single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). Our results demonstrated the fibre-like pathogenic behaviors of CNTs, reflected by increased total protein content in the lavageate from peritoneal cavities and increased serum levels of inflammatory cytokines, IL-1ß and IL-6. The pro-inflammatory effects of CNTs were further validated with exposure to in vitro cultured monocyte-macrophage cells, J774A.1, as SWNTs and MWNTs significantly increased the expression levels of pro-inflammatory genes IL-1ß and IL-6. Collectively, our data demonstrate that SWNTs and MWNTs provoke considerable inflammation presumably due to their fibre-like shape, and further confirm the length- and size-related structure-activity relationship for CNTs in stimulating inflammatory responses.