Background: The mevalonate pathway generates endogenous cholesterol and intermediates including geranylgeranyl pyrophosphate (GGPP). By reducing GGPP production, statins exert pleiotropic or cholesterol-independent effects. The potential regulation of GGPP homeostasis through dietary intake and the interaction with concomitant statin therapy is unknown. Methods: We developed a sensitive HPLC technique to quantify dietary GGPP and conducted proteomics, qRT-PCR screening and western blot to determine signaling cascades, gene expression, protein-protein interaction and protein membrane trafficking in wild type and transgenic rats. Results: GGPP contents were highly variable depending on food source that differentially regulated blood GGPP levels in rats. Diets containing intermediate and high GGPP reduced or abolished the effects of statins in rats with hypoxia- and monocrotaline-induced pulmonary hypertension: this was rescuable by methyl-allylthiosulfinate and methyl-allylthiosulfinate-rich garlic extracts. In human pulmonary artery smooth muscle cells (HPASMCs) treated with statins, hypoxia activated RhoA in an extracellular GGPP-dependent manner. Hypoxia-induced ROCK2/Rab10 signaling was prevented by statin and recovered by exogenous GGPP. The hypoxia-activated RhoA/ROCK2 pathway in rat and HPASMCs upregulated the expression of Ca 2+ -sensing receptor (CaSR) and hypoxia-induced mitogenic factor/FIZZ1 (HIMF), a mechanism attenuated by statin treatment and regained with exogenous GGPP. Rab10-knockdown almost abrogated hypoxia-promoted CaSR membrane-trafficking, a process diminished by statin and resumed by exogenous GGPP. Hypoxia-induced pulmonary hypertension was reduced in rats with CaSR mutated at the binding motif of HIMF and the interaction between dietary GGPP and statin efficiency was abolished. In humans fed with a high GGPP diet, blood GGPP levels were increased, and this abolished statin-lowering effects on plasma GGPP and hypoxia-enhanced RhoA activity of blood monocytes that were both also rescued by garlic extracts. Conclusions: There is important dietary regulation of GGPP levels that interferes with the effects of statin therapy in experimental pulmonary hypertension. These observations rely on a key and central role of i) RhoA-ROCK2 cascade activation and ii) Rab10-faciliated CaSR membrane trafficking with iii) subsequent overexpression and binding of HIMF to CaSR. These findings warrant clinical investigation for the treatment of pulmonary hypertension and perhaps other diseases by combining statin together with garlic-derived methyl-allylthiosulfinate or garlic extracts and thus circumventing dietary GGPP variations.

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Background: Pulmonary arterial hypertension is an incurable disease, in which the extracellular CaSR (calcium sensing receptor) is mechanistically important. This study was aimed to genetically link the CaSR gene and function to the disease severity. Methods: Sanger sequencing, Sugen/hypoxia pulmonary arterial hypertension rat model, CaSR mutated rat, transcriptional reporter assay and measurement of CaSR activity were used. Results: Sanger sequencing identified a significant association between the variant rs1042636(A>G), located in CaSR exon 7, and idiopathic pulmonary arterial hypertension (IPAH) formation in patients. The frequency of 2968G homozygotes was higher in patients with IPAH compared with healthy individuals (23.6% versus 17.5%; P =0.001, OR=1.864), and the minor alleles of rs6776158, rs1048213, and rs9883099, located in CaSR promoter, raised the IPAH odds ratio to 2.173. Patients with IPAH carrying heterozygotes or homozygotes genotype of rs1042636 showed markedly higher pulmonary artery pressure and reduced survival compared with individuals carrying the wild-type allele. The minor alleles of rs6776158, rs1048213, and rs9883099 increased CaSR expression in reporter assay. In Sugen/hypoxia pulmonary arterial hypertension rats, the point mutation replicating rs1042636 found in IPAH exacerbated pulmonary arterial hypertension severity by promoting the overexpression and the enhanced activity of CaSR. Conclusions: Our functional genomic analysis thus indicates that the CaSR minor alleles of rs1042636, rs6776158, rs1048213, and rs9883099 contribute to the development and severity of IPAH. These findings may benefit clinical prognosis and treatment for IPAH.

The impact of inlet flow variations on turbomachinery flow is common in the real world, resulting in undesirable performance deteriorations in engineering. The origin of performance changes and how to evaluate the changes require to be studied, which is of high significance in both academic and engineering communities. On use of CFD and the nonintrusive polynomial chaos (NIPC) method, performance impact considering the stochastic variations of inlet flow angle for a transonic compressor rotor blade is studied in the paper. A detailed grid-independent study assisted by Richardson extrapolation is firstly presented to illustrate the reliability of CFD solutions. Then the implementations of NIPC employing adaptive sparse grid are introduced. Performance uncertainty quantification of NASA Rotor 67 is evaluated using NIPC and the effects of different distributions of inlet flow angle variation (IFAV), different ranges of IFAV on the performance changes at different operation conditions are presented. Finally, statistical analysis on flow solutions by Monte Carlo simulation is performed. The adiabatic efficiency along span at the outlet and the flow solutions in the blade passage are presented and discussed to demonstrate the impact mechanisms of IFAV.