Huntington's disease phenotypes are improved via mTORC1 modulation by small molecule therapy.

Huntington's Disease (HD) is a dominantly inherited neurodegenerative disease for which the major causes of mortality are neurodegeneration-associated aspiration pneumonia followed by cardiac failure. mTORC1 pathway perturbations are present in HD models and human tissues. Amelioration of mTORC1 deficits by genetic modulation improves disease phenotypes in HD models, is not a viable therapeutic strategy. Here, we assessed a novel small molecule mTORC1 pathway activator, NV-5297, for its improvement of the disease phenotypes in the N171-82Q HD mouse model. Oral dosing of NV-5297 over 6 weeks activated mTORC1, increased striatal volume, improved motor learning and heart contractility. Further, the heart contractility, heart fibrosis, and survival were improved in response to the cardiac stressor isoprenaline when compared to vehicle-treated mice. Cummulatively, these data support mTORC1 activation as a therapeutic target in HD and consolidates NV-5297 as a promising drug candidate for treating central and peripheral HD phenotypes and, more generally, mTORC1-deficit related diseases.

Clinical characterization of familial hypercholesterolemia due to an amish founder mutation in Apolipoprotein B.

BACKGROUND: Familial hypercholesterolemia (FH) due to a founder variant in Apolipoprotein B (ApoBR3500Q) is reported in 12% of the Pennsylvania Amish community. By studying a cohort of ApoBR3500Q heterozygotes and homozygotes, we aimed to characterize the biochemical and cardiac imaging features in children and young adults with a common genetic background and similar lifestyle. METHODS: We employed advanced lipid profile testing, carotid intima media thickness (CIMT), pulse wave velocity (PWV), and peripheral artery tonometry (PAT) to assess atherosclerosis in a cohort of Amish ApoBR3500Q heterozygotes (n = 13), homozygotes (n = 3), and their unaffected, age-matched siblings (n = 9). ApoBR3500Q homozygotes were not included in statistical comparisons. RESULTS: LDL cholesterol (LDL-C) was significantly elevated among ApoBR3500Q heterozygotes compared to sibling controls, though several ApoBR3500Q heterozygotes had LDL-C levels in the normal range. LDL particles (LDL-P), small, dense LDL particles, and ApoB were also significantly elevated among subjects with ApoBR3500Q. Despite these differences in serum lipids and particles, CIMT and PWV were not significantly different between ApoBR3500Q heterozygotes and controls in age-adjusted analysis. CONCLUSIONS: We provide a detailed description of the serum lipids, atherosclerotic plaque burden, vascular stiffness, and endothelial function among children and young adults with FH due to heterozygous ApoBR3500Q. Fasting LDL-C was lower than what is seen with other forms of FH, and even normal in several ApoBR3500Q heterozygotes, emphasizing the importance of cascade genetic testing among related individuals for diagnosis. We found increased number of LDL particles among ApoBR3500Q heterozygotes but an absence of detectable atherosclerosis.

Is the child at risk? Cardiovascular remodelling in children born to diabetic mothers.

OBJECTIVE: The objective of this study was to assess differences in myocardial systolic and diastolic function and vascular function in children 2-5 years of age born to diabetic as compared to non-diabetic mothers. METHODS: This study was a retrospective cohort conducted in 2016 at The Aga Khan University Hospital, Karachi, Pakistan. It included children between 2 and 5 years of age born to mothers with and without exposure to diabetes in utero (n = 68 in each group) and who were appropriate for gestational age. Myocardial morphology and function using echocardiogram and carotid intima media thickness (cIMT) and pulse wave velocity was performed to evaluate cardiac function as well as macrovascular remodelling in these children. Multiple linear regression was used to compare the groups. RESULTS: There was no significant difference in cardiac morphology, myocardial systolic and diastolic function, and macrovascular assessment between the exposed and unexposed groups of AGA children. Subgroup analysis demonstrated a significantly decreased mitral E/A ratio in children whose mothers were on medications as compared to those on dietary control (median [IQR] = 1.7 [1.6-1.9] and 1.56 [1.4-1.7], respectively, p = 0.02), and a higher cIMT in children whose mothers were on medication as compared to controls (0.48 [0.44-0.52] and 0.46 [0.44-0.50], respectively, p = 0.03). CONCLUSION: In utero exposure to uncontrolled maternal diabetes has an effect on the cardiovascular structure and function in children aged 2-5 years. However, future work requires long-term follow-up from fetal to adult life to assess these changes over the life course.

Cardiac mTORC1 Dysregulation Impacts Stress Adaptation and Survival in Huntington's Disease.

Huntington's disease (HD) is a dominantly inherited neurological disorder caused by CAG-repeat expansion in exon 1 of Huntingtin (HTT). But in addition to the neurological disease, mutant HTT (mHTT), which is ubiquitously expressed, impairs other organ systems. Indeed, epidemiological and animal model studies suggest higher incidence of and mortality from heart disease in HD. Here, we show that the protein complex mTORC1 is dysregulated in two HD mouse models through a mechanism that requires intrinsic mHTT expression. Moreover, restoring cardiac mTORC1 activity with constitutively active Rheb prevents mortality and relieves the mHTT-induced block to hypertrophic adaptation to cardiac stress. Finally, we show that chronic mTORC1 dysregulation is due in part to mislocalization of endogenous Rheb. These data provide insight into the increased cardiac-related mortality of HD patients, with cardiac mHTT expression inhibiting mTORC1 activity, limiting heart growth, and decreasing the heart's ability to compensate to chronic stress.