Mechanisms regulating cerebral hypoperfusion in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy

A CADASIL NOTCH3 mutation leads to clonal hematopoiesis and expansion of Dnmt3a-R878H hematopoietic clones

Clonal hematopoiesis (CH) is nearly universal in the elderly. The molecular and cellular mechanisms driving CH and the clinical consequences of carrying clonally derived mutant mature blood cells are poorly understood. We recently identified a C223Y mutation in the extracellular domain (ECD) of NOTCH3 as a putative CH driver in mice. Provocatively, germline NOTCH3 ECD mutations perturbing cysteine numbers cause Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), a type of vascular dementia, suggesting an unexpected link between CADASIL and CH. Here, we formally demonstrated that mouse hematopoietic stem and progenitor cells (HSPCs) expressing CADASIL-related NOTCH3C455R exhibit a proliferative advantage resulting in robust cellular expansion in vivo and in vitro. Co-expression of NOTCH3C455R and Dnmt3aR878H, homologous to a frequent human CH mutation, increased the fitness of NOTCH3C455R HSPCs, demonstrating their functional cooperation. Surprisingly, the presence of NOTCH3C455R hematopoietic cells supported the expansion of Dnmt3aR878H HSPCs in a non-cell autonomous fashion in vivo, strongly suggesting that CADASIL patients and asymptomatic carriers can be highly predisposed to DNMT3AR882H-driven CH. Considering that CADASIL-related NOTCH3 mutations are more frequent in the general population than anticipated (~1 carrier in 400 people), the effect of these NOTCH3 mutations on CH development should be considered.

Novel grading system for CADASIL severity: A multicenter cross-sectional study

Background

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited progressive cerebral microangiopathy with considerable phenotypic variability. The purpose of this study was to describe the generalizability of a recently proposed grading system of CADASIL across multiple centers in the United States.

Methods

Electronic medical records (EMR) of an initial neurological assessment of adult patients with confirmed CADASIL were reviewed across 5 tertiary referral medical centers with expertise in CADASIL. Demographic, vascular risk factors, and neuroimaging data were abstracted from EMR. Patients were categorized into groups according to the proposed CADASIL grading system: Grade 0 (asymptomatic), Grade 1 (migraine only), Grade 2 (stroke, TIA, or MCI), Grade 3 (gait assistance or dementia), and Grade 4 (bedbound or end-stage). Inter-rater reliability (IRR) of grading was tested in a subset of cases.

Results

We identified 138 patients with a mean age of 50.9 ± 13.1 years, and 57.2% were female. The IRR was acceptable over 33 cases (κ=0.855, SD 0.078, p<0.001) with 81.8% being concordant. There were 15 patients (10.9%) with Grade 0, 50 (36.2%) with Grade 1, 61 (44.2%) with Grade 2, 12 (8.7%) with Grade 3, and none with Grade 4. Patients with a lower severity grade (grade 0 vs 3) tended to be younger (49.5 vs. 61.9 years) and had a lower prevalence of hypertension (50% vs. 20%, p = 0.027) and diabetes mellitus (0% vs. 25%, p = 0.018). A higher severity grade was associated with an increased number of vascular risk factors (p = 0.02) and independently associated with hypertension and diabetes (p<0.05). Comparing Grade 0 vs. 3, cortical thickness tended to be greater (2.06 vs. 1.87 mm; p = 0.06) and white matter hyperintensity volume tended to be lower (54.7 vs. 72.5 ml; p = 0.73), but the differences did not reach significance.

Conclusion

The CADASIL severity grading system is a pragmatic, reliable system for characterizing CADASIL phenotype that does not require testing beyond that done in standard clinical practice. Higher severity grades tended to have a higher vascular risk factor burden. This system offers a simple method of categorizing CADASIL patients which may help to describe populations in observational and interventional studies.

Antiplatelet use and CADASIL: a retrospective observational analysis

OBJECTIVES

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is hallmarked by age-dependent accumulation of microangiopathy with antiplatelet medications commonly used for stroke prevention though without known therapeutic benefit. Our objective was to identify whether antiplatelet therapy impacted the incidence of acute ischemic stroke (AIS) or intracerebral hemorrhage (ICH) in those with reported CADASIL.

MATERIALS AND METHODS

Owing to the rarity of the disease, we performed a retrospective study of anonymized data from the international TriNetX Research Network (Oct 2015 through January 2021). Individuals had an ICD-10 code (I67.850) for CADASIL. The primary outcome was incidence of validated ICD-10 codes for AIS (I63) and ICH (I61) linked with unique hospital admission encounters. The primary exposure was use of an antiplatelet medication for at least 1 month prior to the primary outcome. Age-adjusted logistic regression was used for likelihood ratios.

RESULTS

We identified 455 individuals: 36% female, 40 (8.8%) antiplatelet exposed. Those with antiplatelet use were older (antiplatelet: 61±12 years vs. unexposed: 57±14 years, p = 0.034) with similar rates of AIS [antiplatelet: 23%(9/40) vs. unexposed: 14%(60/415); p=0.18] and ICH [antiplatelet: 3%(1/40) vs. unexposed: 5%(19/415); p = 0.54) and without significant impact on age-adjusted AIS likelihood (OR 1.62, 95%CI 0.73-3.60, p=0.23). Sample size precluded ICH regression analyses.

CONCLUSIONS

Our data suggests that antiplatelet use did not significantly impact incidence of AIS or ICH within a group of individuals with suspected CADASIL This study highlights the need for further understanding of the pathophysiology of CADASIL to lead to disease modifying treatments.