Tumour microbiomes and Fusobacterium genomics in Vietnamese colorectal cancer patients.

Perturbations in the gut microbiome have been associated with colorectal cancer (CRC), with the colonic overabundance of Fusobacterium nucleatum shown as the most consistent marker. Despite its significance in the promotion of CRC, genomic studies of Fusobacterium is limited. We enrolled 43 Vietnamese CRC patients and 25 participants with non-cancerous colorectal polyps to study the colonic microbiomes and genomic diversity of Fusobacterium in this population, using a combination of 16S rRNA gene profiling, anaerobic microbiology, and whole genome analysis. Oral bacteria, including F. nucleatum and Leptotrichia, were significantly more abundant in the tumour microbiomes. We obtained 53 Fusobacterium genomes, representing 26 strains, from the saliva, tumour and non-tumour tissues of six CRC patients. Isolates from the gut belonged to diverse F. nucleatum subspecies (nucleatum, animalis, vincentii, polymorphum) and a potential new subspecies of Fusobacterium periodonticum. The Fusobacterium population within each individual was distinct and in some cases diverse, with minimal intra-clonal variation. Phylogenetic analyses showed that within four individuals, tumour-associated Fusobacterium were clonal to those isolated from non-tumour tissues. Genes encoding major virulence factors (Fap2 and RadD) showed evidence of horizontal gene transfer. Our work provides a framework to understand the genomic diversity of Fusobacterium within the CRC patients, which can be exploited for the development of CRC diagnostic and therapeutic options targeting this oncobacterium.

Protective role of the mitochondrial fusion protein OPA1 in hypertension.

Hypertension is associated with excessive reactive oxygen species (ROS) production in vascular cells. Mitochondria undergo fusion and fission, a process playing a role in mitochondrial function. OPA1 is essential for mitochondrial fusion. Loss of OPA1 is associated with ROS production and cell dysfunction. We hypothesized that mitochondria fusion could reduce oxidative stress that defect in fusion would exacerbate hypertension. Using (a) Opa1 haploinsufficiency in isolated resistance arteries from Opa1+/- mice, (b) primary vascular cells from Opa1+/- mice, and (c) RNA interference experiments with siRNA against Opa1 in vascular cells, we investigated the role of mitochondria fusion in hypertension. In hypertension, Opa1 haploinsufficiency induced altered mitochondrial cristae structure both in vascular smooth muscle and endothelial cells but did not modify protein level of long and short forms of OPA1. In addition, we demonstrated an increase of mitochondrial ROS production, associated with a decrease of superoxide dismutase 1 protein expression. We also observed an increase of apoptosis in vascular cells and a decreased VSMCs proliferation. Blood pressure, vascular contractility, as well as endothelium-dependent and -independent relaxation were similar in Opa1+/- , WT, L-NAME-treated Opa1+/- and WT mice. Nevertheless, chronic NO-synthase inhibition with L-NAME induced a greater hypertension in Opa1+/- than in WT mice without compensatory arterial wall hypertrophy. This was associated with a stronger reduction in endothelium-dependent relaxation due to excessive ROS production. Our results highlight the protective role of mitochondria fusion in the vasculature during hypertension by limiting mitochondria ROS production.

Effect of itraconazole on the pharmacokinetics and pharmacodynamics of fexofenadine in relation to the MDR1 genetic polymorphism.

OBJECTIVE: Our objective was to evaluate the effect of itraconazole, a P-glycoprotein inhibitor, on the pharmacokinetics and pharmacodynamics of fexofenadine, a P-glycoprotein substrate, in relation to the multidrug resistance 1 gene (MDR1) G2677T/C3435T haplotype. METHODS: A single oral dose of 180 mg fexofenadine was administered to 7 healthy subjects with the 2677GG/3435CC (G/C) haplotype and 7 with the 2677TT/3435TT (T/T) haplotype. One hour before the fexofenadine dose, either 200 mg itraconazole or placebo was administered to the subjects in a double-blinded, randomized, crossover manner with a 2-week washout period. Histamine-induced wheal and flare reactions were measured to assess the effects on the antihistamine response. RESULTS: In the placebo phase, pharmacokinetic parameters of fexofenadine showed no statistically significant difference between 2 MDR1 haplotypes; the area under the curve from time 0 to infinity (AUC(0-infinity)) of fexofenadine in the T/T and G/C groups was 5194.0 +/- 1910.8 and 4040.4 +/- 1832.2 ng.mL(-1).h(-1), respectively (P = .271), and the oral clearance (CL/F) was 530.9 +/- 191.1 and 806.0 +/- 355.3 mL.h(-1).kg(-1), respectively (P = .096). The disposition of itraconazole, a substrate of P-glycoprotein, was not significantly different between the 2 haplotypes. After itraconazole pretreatment, however, the differences in fexofenadine pharmacokinetics became statistically significant; the mean fexofenadine AUC(0-infinity) in the T/T group was significantly higher than that in the G/C group (15,630.6 +/- 5070.0 and 9252.9 +/- 2044.1 ng/mL.h, respectively; P = .007), and CL/F of the T/T subjects was lower than that of the G/C subjects (167.0 +/- 33.3 and 292.3 +/- 42.2 mL.h(-1).kg(-1), respectively; P < .001). Itraconazole pretreatment caused more than a 3-fold increase in the peak concentration of fexofenadine and the area under the curve to 6 hours compared with the placebo phase. This resulted in a significantly higher suppression of the histamine-induced wheal and flare reactions in the itraconazole pretreatment phase compared with those in the placebo phase. CONCLUSION: The effect of MDR1 G2677T/C3435T haplotypes on fexofenadine disposition are magnified in the presence of itraconazole. Itraconazole pretreatment significantly altered the disposition of fexofenadine and thus its peripheral antihistamine effects.