Sex differences in coronary artery disease severity and mortality: the impact of conventional cardiovascular risk factors

It is still unknown whether traditional risk factors may have a sex specific impact on the severity of coronary artery disease (CAD) and subsequent mortality in acute coronary syndromes (ACS). We identified 14 793 patients who underwent coronary angiography for acute coronary syndromes in the ISACS-TC (NCT01218776) registry from 2010 to 2019. The main outcome measure was the association between conventional risk factors and severity of CAD and its relationship with 30-day mortality. Risk ratios (RRs) and 95% CIs were calculated from the ratio of the absolute risks of women versus men using inverse probability of weighting. Severity of disease was categorized as obstructive (≥50% stenosis) versus nonobstructive CAD, specifically Ischemia and No Obstructive Coronary Artery disease (INOCA) and Myocardial Infarction with Non obstructive Coronary Arteries (MINOCA). The RR ratio for obstructive CAD in women versus men among people without diabetes mellitus was 0.49(95%CI,0.41–0.60) and among those with diabetes mellitus was 0.89(95% CI,0.62–1.29), with an interaction by diabetes mellitus status of P =0.002. Exposure to smoking shifted the RR ratios from 0.50 (95% CI, 0.41–0.61) in nonsmokers to 0.75 (95%CI, 0.54–1.03) in current smokers, with an interaction by smoking status of P=0.018. There were no significant sex-related interactions with hypercholesterolemia and hypertension. Women with obstructive CAD had higher 30-day mortality rates than men (RR, 1.75; 95% CI, 1.48–2.07). No sex differences in mortality were observed in patients with INOCA/MINOCA. In conclusion, obstructive CAD in women signifies a higher risk for mortality compared with men. Current smoking and diabetes mellitus disproportionally increase the risk of obstructive CAD in women. Achieving the goal of improving cardiovascular health in women still requires intensive efforts toward further implementation of lifestyle and treatment interventions.

Interaction between APOE4 genotype and environmental risk factors in Alzheimer's disease

Alzheimer's disease (AD) is probably caused by both genetic and environmental risk factors. The major genetic risk factor is the E4 variant of apolipoprotein E gene called apoE4. Several risk factors for developing AD have been identified including lifestyle, such as dietary habits. The mechanisms behind the AD pathogenesis and the onset of cognitive decline in the AD brain are presently unknown. In this study we wanted to characterize the effects of the interaction between environmental risk factors and apoE genotype on neurodegeneration processes, with particular focus on behavioural studies and neurodegenerative processes at molecular level. Towards this aim, we used 6 months-old apoE4 and apoE3 Target Replacement (TR) mice fed on different diets (high intake of cholesterol and high intake of carbohydrates). These mice were evaluated for learning and memory deficits in spatial reference (Morris Water Maze (MWM)) and contextual learning (Passive Avoidance) tasks, which involve the hippocampus and the amygdala, respectively. From these behavioural studies we found that the initial cognitive impairments manifested as a retention deficit in apoE4 mice fed on high carbohydrate diet. Thus, the genetic risk factor apoE4 genotype associated with a high carbohydrate diet seems to affect cognitive functions in young mice, corroborating the theory that the combination of genetic and environmental risk factors greatly increases the risk of developing AD and leads to an earlier onset of cognitive deficits. The cellular and molecular bases of the cognitive decline in AD are largely unknown. In order to determine the molecular changes for the onset of the early cognitive impairment observed in the behavioural studies, we performed molecular studies, with particular focus on synaptic integrity and Tau phosphorylation. The most relevant finding of our molecular studies showed a significant decrease of Brain-derived Neurotrophic Factor (BDNF) in apoE4 mice fed on high carbohydrate diet. Our results may suggest that BDNF decrease found in apoE4 HS mice could be involved in the earliest impairment in long-term reference memory observed in behavioural studies. The second aim of this thesis was to study possible involvement of leptin in AD. There is growing evidence that leptin has neuroprotective properties in the Central Nervous System (CNS). Recent evidence has shown that leptin and its receptors are widespread in the CNS and may provide neuronal survival signals. However, there are still numerous questions, regarding the molecular mechanism by which leptin acts, that remain unanswered. Thus, given to the importance of the involvement of leptin in AD, we wanted to clarify the function of leptin in the pathogenesis of AD and to investigate if apoE genotype affect leptin levels through studies in vitro, in mice and in human. Our findings suggest that apoE4 TR mice showed an increase of leptin in the brain. Leptin levels are also increased in the cerebral spinal fluid of AD patients and apoE4 carriers with AD have higher levels of leptin than apoE3 carriers. Moreover, leptin seems to be expressed by reactive glial cells in AD brains. In vitro, ApoE4 together with Amyloid beta increases leptin production by microglia and astrocytes. Taken together, all these findings suggest that leptin replacement might not be a good strategy for AD therapy. Our results show that high leptin levels were found in AD brains. These findings suggest that, as high leptin levels do not promote satiety in obese individuals, it might be possible that they do not promote neuroprotection in AD patients. Therefore, we hypothesized that AD brain could suffer from leptin resistance. Further studies will be critical to determine whether or not the central leptin resistance in SNC could affect its potential neuroprotective effects.

Modeling Alzheimer disease with iPSCs and mouse model for the identification of risk factors, new targets, and potential therapeutical strategies

Alzheimer's disease (AD) is the most common neurodegenerative disease in elderly. Donepezil is the first-line drug used for AD. In section one, the experimental activity was oriented to evaluate and characterize molecular and cellular mechanisms that contribute to neurodegeneration induced by the Aβ1-42 oligomers (Aβ1-42O) and potential neuroprotective effects of the hybrids feruloyl-donepezil compound called PQM130. The effects of PQM130 were compared to donepezil in a murine AD model, obtained by intracerebroventricular (i.c.v.) injection of Aβ1-42O. The intraperitoneal administration of PQM130 (0.5-1 mg/kg) after i.c.v. Aβ1-42O injection improved learning and memory, protecting mice against spatial cognition decline. Moreover, it reduced oxidative stress, neuroinflammation and neuronal apoptosis, induced cell survival and protein synthesis in mice hippocampus. PQM130 modulated different pathways than donepezil, and it is more effective in counteracting Aβ1-42O damage. The section two of the experimental activity was focused on studying a loss of function variants of ABCA7. GWA studies identified mutations in the ABCA7 gene as a risk factor for AD. The mechanism through which ABCA7 contributes to AD is not clear. ABCA7 regulates lipid metabolism and critically controls phagocytic function. To investigate ABCA7 functions, CRISPR/Cas9 technology was used to engineer human iPSCs and to carry the genetic variant Y622*, which results in a premature stop codon, causing ABCA7 loss-of-function. From iPSCs, astrocytes were generated. This study revealed the effects of ABCA7 loss in astrocytes. ABCA7 Y622* mutation induced dysfunctional endocytic trafficking, impairing Aβ clearance, lipid dysregulation and cell homeostasis disruption, alterations that could contribute to AD. Though further studies are needed to confirm the PQM130 neuroprotective role and ABCA7 function in AD, the provided results showed a better understanding of AD pathophysiology, a new therapeutic approach to treat AD, and illustrated an innovative methodology for studying the disease.

Traditional risk factors and lifetime risk of acute coronary events

Objective: To investigate the association between the four traditional coronary heart disease (CHD) risk factors (hypertension, smoking, hypercholesterolemia, and diabetes) and outcomes of first ACS. Methods: Data were drawn from the ISACS Archives. The study participants consisted of 70953 patients with first ACS, but without prior CHD. Primary outcomes were patient’ age at hospital presentation and 30-day all-cause mortality. The risk ratios for mortality among subgroups were calculated using a balancing strategy by inverse probability weighting. Trends were evaluated by Pearson's correlation coefficient (r). Results: For fatal ACS (n=6097), exposure to at least one traditional CHD-risk factor ranged from 77.6% in women to 74.5% in men. The presence of all four CHD-risk factors significantly decreased the age at time of ACS event and death by nearly half a decade compared with the absence of any traditional risk factors in both women (from 67.1±12.0 to 61.9±10.3 years; r=-0.089, P<0.001) and men (from 62.8±12.2 to 58.9±9.9 years; r=-0.096, P<0.001). By contrast, there was an inverse association between the number of traditional CHD-risk factors and 30-day mortality. The mortality rates in women ranged from 7.7% with four traditional CHD-risk factors to 16.3% with no traditional risk factors (r=0.073, P<0.001). The corresponding rates in men were 4.8% and 11.5% (r=0.078, P<0.001), respectively. The risk ratios among individuals with at least one CHD-risk factors vs. those with no traditional risk factors were 0.72 (95%CI:0.65-0.79) in women and 0.64 (95%CI:0.59-0.70) in men. This association was consistent among patient subgroups managed with guideline-recommended therapeutic options. Conclusions: The vast majority of patients who die for ACS have traditional CHD-risk factor exposure. Patients with CHD-risk factors die much earlier in life, but they have a lower relative risk of 30-day mortality than those with no traditional CHD-risk factors, even in the context of equitable evidence‐based treatments after hospital admission.