Citations

AbstractBackgroundAPOE ε4 is the strongest genetic risk factor for late‐onset Alzheimer’s disease (AD). The contribution of microglial APOE4 to AD pathogenesis is unknown, although APOE has the most enriched gene expression in neurodegenerative microglia (MGnD).MethodGeneration of CX3CR1‐CREERT2 mice crossed to APOE‐KI(E3 and E4)fl/fl: APP/PS1 and APOE‐KI(E3 and E4)fl/fl: P301S mice. Microglia and astrocytes were isolated and sequenced using either bulk RNA‐seq (MGnD‐Paradigm) or single‐cell RNA‐seq. Crosstalk between cells was determined using the NichenetR database and validated using 1) recombinant Lgals3 intracranial injection into APP/PS1 mice and 2) adoptive transfer of microglia, from APOE3‐KI, APOE4‐KI, and APOE4‐cKO mice challenged with labeled apoptotic neurons, into WT mice and isolation of astrocytes. Validation in the brain of AD donors carrying the APOE e3/3 and e3/4 alleles.ResultHere we show, in mice and in humans, a negative role of microglial APOE4 in the induction of MGnD response to neurodegeneration. Deletion of microglial APOE4 restores MGnD phenotype, associated with neuroprotection in P301S tau transgenic mice, and decreases pathology in APP/PS1 mice. MGnD‐astrocyte crosstalk associated with b‐amyloid (Ab) plaque encapsulation and clearance is mediated via Lgals3 signaling following microglial APOE4 deletion. In the brain of AD donors carrying the APOE ε4 allele, we found a sex‐dependent reciprocal induction of AD risk factors associated with suppression of MGnD genes in females, including LGALS3, as compared to APOE ε3/3 carriers. Mechanistically, APOE4‐mediated induction of ITGB8‐TGFb signaling impairs MGnD response via upregulation of TGFb‐mediated microglial homeostatic checkpoints, including INPP5D. Microglial deletion of Inpp5d restores MGnD‐astrocyte crosstalk and facilitates plaque clearance in APP/PS1 mice. Genetic and pharmacological blocking of ITGB8‐TGFb signaling enhanced MGnD response associated with increased plaque clearance in AD mice.ConclusionWe identify the microglial APOE4‐ITGB8‐TGFb pathway as a negative regulator of microglia‐astrocyte response to AD pathology, and restoring MGnD phenotype via blocking ITGB8‐TGFb signaling may provide new molecular targets to modulate and restore functional microglia in AD.

Background: Catheter ablation for ventricular tachycardia (VT) has been increasingly performed. While it is estimated that 42% of adults in the United States are obese, the impact of obesity on VT ablation procedures remains unclear. Objective: This study aimed to evaluate the procedural outcomes and 30-day readmission among non-obese and obese patients who underwent catheter ablation of VT. Method: Using the Nationwide Readmissions Database, our study included patients aged 18 years or older who underwent catheter ablation for VT between 2017 and 2020. The study cohort was stratified into non-obese (BMI < 30kg/m 2 ) and obese (BMI ≥ 30kg/m 2 ). The in-hospital procedural outcome and 30-day readmission were analyzed between these groups. Results: Our study included a total of 835 obese patients (19.7%) and 3393 non-obese patients (80.3%). Obese group had a higher rate of prolonged length of stay (>7 days) (37.6% vs 31.2%, p<0.01) and a higher cost of hospitalization ($39 983 vs $37 015, p<0.01). Overall, there were no significant differences in early mortality (4.5% vs 3.8%, p=0.45). Apart from increased vascular complications in the obese group (1.8% vs 0.9%, p=0.03), there were no significant differences in other procedural complications between both groups. There were no significant differences in 30-day readmission rates between obese and non-obese groups (15.5% vs 14.1%, p=0.38). Additional analysis performed in the obese group revealed a non-significant decreasing trend in early mortality rate post-procedurally (5.4% to 4.8%, P trend = 0.66). On multivariable analysis, heart failure was associated with a higher risk of 30-day readmission in obese patients (OR: 2.00; 95% CI: 1.01-3.99; p=0.05). Conclusion: Our study suggests that catheter ablation for VT can be performed relatively safely in obese patients without significant differences in 30-day mortality and readmission outcomes. Patients should not be excluded from VT ablation on the basis of obesity.