Heart failure-induced microbial dysbiosis contributes to colonic tumour formation in mice.

AIMS: Heart failure (HF) and cancer are the leading causes of death worldwide. Epidemiological studies revealed that HF patients are prone to develop cancer. Preclinical studies provided some insights into this connection, but the exact mechanisms remain elusive. In colorectal cancer (CRC), gut microbial dysbiosis is linked to cancer progression and recent studies have shown that HF patients display microbial dysbiosis. This current study focussed on the effects of HF-induced microbial dysbiosis on colonic tumour formation. METHODS AND RESULTS: C57BL/6J mice were subjected to myocardial infarction (MI), with sham surgery as control. After six weeks faeces were collected, processed for 16 s rRNA sequencing, and pooled for faecal microbiota transplantation. CRC tumour growth was provoked in germ-free mice by treating them with Azoxymethane/Dextran sodium sulphate. The CRC mice were transplanted with faeces from MI or sham mice. MI-induced HF resulted in microbial dysbiosis, characterized by a decreased α-diversity and microbial alterations on the genus level, several of which have been associated with CRC. We then performed faecal microbiota transplantation with faeces from HF mice in CRC mice, which resulted in a higher endoscopic disease score and an increase in the number of tumours in CRC mice. CONCLUSION: We demonstrated that MI-induced HF contributes to colonic tumour formation by altering the gut microbiota composition, providing a mechanistic explanation for the observed association between HF and increased risk for cancer. Targeting the microbiome may present as a tool to mitigate HF-associated co-morbidities, especially cancer.

Sex differences in associations of comorbidities with incident cardiovascular disease: focus on absolute risk.

Aim: To examine sex differences in associations of obesity, type-2 diabetes, hypertension, and atrial fibrillation (AF) with incident cardiovascular disease (CVD), focusing on absolute risk measures. Methods and results: We included a total of 7994 individuals (mean age 49.1 years; 51.2% women) without prior CVD from the PREVEND (Prevention of Renal and Vascular End-stage Disease) cohort with a median follow-up of 12.5 years. Using Poisson regression, we calculated the increase in absolute as well as relative CVD risk associated with a comorbidity using incidence rate differences (IRD = IRcomorbidity-IRno-comorbidity) and incidence rate ratios (IRR = IRcomorbidity/IRno-comorbidity), respectively. Sex differences were presented as women-to-men differences (WMD = IRDwomen-IRDmen) and women-to-men ratios (WMR = IRRwomen/IRRmen). Absolute CVD risk was lower in women than in men (IRwomen: 6.73 vs. IRmen: 14.58 per 1000 person-years). While increase in absolute CVD risk associated with prevalent hypertension was lower in women than in men [WMD: -6.12, 95% confidence interval: (-9.84 to -2.40), P = 0.001], increase in absolute CVD risk associated with prevalent obesity [WMD: -4.25 (-9.11 to 0.61), P = 0.087], type-2 diabetes [WMD: -1.04 (-14.36 to 12.29), P = 0.879] and AF [WMD: 18.39 (-39.65 to 76.43), P = 0.535] did not significantly differ between the sexes. Using relative risk measures, prevalent hypertension [WMR: 1.49%, 95% confidence interval: (1.12-1.99), P = 0.006], type-2 diabetes [WMR: 1.73 (1.09-2.73), P = 0.019], and AF [WMR: 2.53 (1.12-5.70), P = 0.025] were all associated with higher CVD risk in women than in men. Conclusion: Increase in absolute risk of developing CVD is higher in hypertensive men than in hypertensive women, but no substantial sex-related differences were observed among individuals with obesity, type-2 diabetes and AF. On a relative risk scale, comorbidities, in general, confer a higher CVD risk in women than in men.

A Molecular Mechanism Underlying Genotype-Specific Intrahepatic Cholestasis Resulting From MYO5B Mutations.

BACKGROUND AND AIMS: Progressive familial intrahepatic cholestasis (PFIC) 6 has been associated with missense but not biallelic nonsense or frameshift mutations in MYO5B, encoding the motor protein myosin Vb (myoVb). This genotype-phenotype correlation and the mechanism through which MYO5B mutations give rise to PFIC are not understood. The aim of this study was to determine whether the loss of myoVb or expression of patient-specific myoVb mutants can be causally related to defects in canalicular protein localization and, if so, through which mechanism. APPROACH AND RESULTS: We demonstrate that the cholestasis-associated substitution of the proline at amino acid position 600 in the myoVb protein to a leucine (P660L) caused the intracellular accumulation of bile canalicular proteins in vesicular compartments. Remarkably, the knockout of MYO5B in vitro and in vivo produced no canalicular localization defects. In contrast, the expression of myoVb mutants consisting of only the tail domain phenocopied the effects of the Myo5b-P660L mutation. Using additional myoVb and rab11a mutants, we demonstrate that motor domain-deficient myoVb inhibited the formation of specialized apical recycling endosomes and that its disrupting effect on the localization of canalicular proteins was dependent on its interaction with active rab11a and occurred at the trans-Golgi Network/recycling endosome interface. CONCLUSIONS: Our results reveal a mechanism through which MYO5B motor domain mutations can cause the mislocalization of canalicular proteins in hepatocytes which, unexpectedly, does not involve myoVb loss-of-function but, as we propose, a rab11a-mediated gain-of-toxic function. The results explain why biallelic MYO5B mutations that affect the motor domain but not those that eliminate myoVb expression are associated with PFIC6.