Citations

Abstract Background Despite recent approval of monoclonal antibodies that reduce amyloid (Ab) accumulation, the development of disease‐modifying strategies targeting the underlying mechanisms of Alzheimer’s Disease (AD) are urgently needed. We identified mitochondrial complex I (mtCI) as a small‐molecule druggable target for AD. Using cryo‐EM, we previously demonstrated that the neuroprotective tool compound CP2 directly binds to the Q‐site of mtCI and weakly inhibits its activity. Method Rational design and extensive structure‐activity relationship studies using CP2 as a tool compound allowed the development of novel classes of partial mtCI inhibitors with high selectivity, specificity, safety, and improved drug‐like properties. Target engagement, selectivity, efficacy, safety and the direct binding to mtCI were demonstrated using multiple in vitro assays. Efficacy in vivo was established using APP/PS1 mice. The best new leads, C458 and C273, were evaluated as preclinical candidates. Result Like CP2, C458 and C273 weakly inhibit mtCI, leading to AMPK activation, which triggers a neuroprotective stress response. This response enhances oxidative stress protection, promotes autophagy, and increases mitochondrial biogenesis and turnover, ultimately protecting against Aβ toxicity. Pretreatment with the irreversible mtCI inhibitor rotenone (at non‐toxic concentrations) blocked C458 and C273 from binding to mtCI and abrogated their protection against Aβ toxicity. Both C458 and C273 exhibited excellent bioavailability, blood–brain barrier penetrance, and a clean safety profile in the CEREP 44 safety panel. Chronic administration of C458 (25 mg/kg/day in drinking water ad lib ) to APP/PS1 mice for 7 months preserved cognition, improved long‐term potentiation, reduced oxidative stress and inflammation, and enhanced mitochondrial biogenesis. Similarly, C273 (20, 50, or 80 mg/kg/day) administered to C57BL/6 mice for one month showed no detectable side effects or toxicity in the heart or liver. Conclusion Mechanistic studies revealed that C458 and C273 activate a mitochondrial stress response, augmenting mitochondrial biogenesis, antioxidant signaling, and autophagy, which collectively provided protection against Aβ toxicity in multiple in vitro and in vivo models of AD. These findings demonstrate that weak mtCI inhibition by novel compounds C458 and C273, with improved drug‐like properties, is neuroprotective. This supports the feasibility of developing safe and efficacious mtCI inhibitors as a disease‐modifying strategy for AD.

ABSTRACT Cytotoxic T lymphocytes (CTLs) are known to eliminate target cells through perforin-mediated, contact-dependent killing - a process limited by the number of effector T cells despite its serial nature. CTLs likely also possess a mass killing mechanism that can eliminate target cells more efficiently. Using CAR-T cells against B7H3 present on B16 tumor targets, we demonstrate that activated T cells can also kill targets in a perforin-independent manner by releasing diffusible TNF and IFNγ capable of killing nearby targets in a paracrine fashion even if they bear no antigen. Against an unperturbed target, paracrine killing is inefficient but is enhanced by the deletion of TNFR1 signaling molecules such as TAK1, HOIP, or TBK1/IKKε. Notably, these molecules are inhibited naturally by pathogen-encoded antagonists. Expression of a microbial-encoded antagonist, such as the Yersinia -encoded YopJ that antagonizes TAK1 or Ebola-encoded VP35 that antagonizes TBK1/IKKε, alters the target cell response to these cytokines from non-lethal to lethal. We propose that target cells are inherently resistant to killing by TNF and IFNγ, but the presence of a microbial factor alters this sensitivity, providing for the selective elimination of the infected cell while minimizing harm to uninfected bystander cells. We propose the term ‘pathogen-restriction’ to describe this discriminatory mechanism. Potentially, any microbial-derived factor that crosstalks with the TNF and IFNγ signaling pathways can function as a pathogen-restriction element. GRAPHICAL ABSTRACT Short Summary T cells use TNF and IFNγ to kill target cells in a paracrine manner where target elimination is restricted by the presence of pathogen-derived factors.

Abstract Background Alzheimer Disease (AD) pathology evolves over decades, and understanding this progression is critical to the understanding of the disease and timing therapeutic interventions. Since individuals with Autosomal Dominant AD (ADAD) develop symptoms around the same age as their parent, it is possible to predict symptom onset and stage individuals by their estimated years to symptom onset (EYO). This approach does not generalize to other forms of AD, thus there is a pressing need for the timecourse of ADAD to be defined in broadly relevant terms. The objective of this project is to validate the Sampled Iterative Local Approximation (SILA) algorithm in a cohort with a known disease timecourse. SILA generates an estimate of time from amyloid positivity (A time ) based on longitudinal PET data. Method We evaluated A time in a longitudinal ADAD sample ( N = 316) with PET PiB data in three ways. First, we compared predicted age at amyloid positive (A+) to observed age at A+ for individuals who became A+ during enrollment. Next, using linear regression, we compared estimated age at A+ to estimated age at symptom onset (EYO=0). Finally, we used generalized additive models to compare the amount of variance in concurrent cognitive performance explained both A time and EYO. Result We observed a mean average error of 1.15 years between actual age at A+ ( N = 26) and the SILA‐predicted A time . Across all participants, SILA‐estimated age at A+ explained 39% of the variance in estimated age at symptom onset ( β = 0.918, p < 0.0001). Finally, we observed a nonlinear association between cognition and both A time and EYO. A time explained 19% of the variance in the general cognitive composite while EYO explained 43% of the variance. Conclusion SILA produces a valid estimate of time‐from‐amyloid positivity in ADAD. This work allows for disease stage in ADAD to be compared to staging for broad forms of AD, which was not previously possible using EYO. However, this work also illustrates that there is a high degree of heterogeneity in preclinical disease duration that is not explained by amyloid alone.

Abstract How embryonic cells generate large clones of cells in the adult represents a fundamental question in biology. Here using melanocyte stem cells (McSCs) in the zebrafish as a model we explore the function of the master melanocyte transcription factor (MITF) in safeguarding McSCs in embryonic development and their potential to pigment large clones in the adult. MITF is well known is for its role in the specification of melanoblasts from the neural crest (NC) and their differentiation into melanocytes, yet little is known about how this activity shapes the stem cell lineages. Here, we use live imaging coupled with single-cell transcriptomics and lineage tracing to show that MITF ( mitfa in zebrafish) protects the melanocyte stem cell (McSC) fate in zebrafish. Utilizing a temperature sensitive mitfa vc7 mutant, we show that loss of Mitfa activity leads to a surprising premature and aberrant expansion of McSC progeny at the niche during embryogenesis, coupled with novel emergent transcriptional cell states. Linage tracing of McSCs from the embryonic to juvenile stages reveals Mitfa activity is subsequently required in regeneration by Schwann cell-like and melanocyte stem cell progenitors that serve as a reservoir for fast-responding pigment progenitors. Thus, the impact of Mitfa loss on the melanocyte lineage is cell-state and stage-specific. The emergent cell states resulting from mitfa loss may have important implications for understanding how reduced MITF activity contributes to human genetic disease and melanoma.

Abstract Background Frontotemporal dementia (FTD) is a neurodegenerative disorder marked by early impairments in executive function and altered prefrontal neural circuitry. These traits are also observed in Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD), suggesting the possibility of shared mechanisms and a role for developmental neurocognitive factors in the onset of FTD. High‐penetrance mutations in GRN, C9orf72, and MAPT increase FTD risk and are suspected to influence neurodevelopment. This study hypothesizes that pre‐symptomatic carriers of these mutations exhibit cognitive and behavioral traits that overlap with those observed in ADD/ADHD. Method This cross‐sectional study analyzed participants from the ARTFL‐LEFFTDS Longitudinal FTLD (ALLFTD) Study. Inclusion criteria restricted the sample to mutation carriers with pathogenic variants in GRN, C9orf72, or MAPT while excluding individuals with prior psychiatric diagnoses (e.g., bipolar disorder, major depressive disorder) and those taking antipsychotic or anxiolytic medications to avoid potential confounding effects on test validity and interpretation. The final sample included N = 338 participants, categorized as pre‐symptomatic mutation carriers ( N = 227) or asymptomatic noncarriers ( N = 111). To assess potential overlaps with ADD/ADHD traits, a targeted subset of measures reflecting executive function, working memory, attention, social behavior, and hyperactivity were extracted from validated cognitive and neuropsychiatric assessments. Mutation carriers were further classified as either converters ( N = 20) who progressed to symptomatic FTD (CDR ≥ 1) or non‐converters ( N = 95) who remained asymptomatic. Only pre‐conversion scores were analyzed for converters. Group comparisons were conducted using general linear models adjusted for age and sex. Result Pre‐symptomatic mutation carriers showed significantly lower verbal fluency ( p = 0.004) and a trend toward reduced working memory ( p = 0.05) compared to noncarriers. Converters exhibited poorer overall cognitive performance ( p <0.0001), verbal fluency ( p = 0.001), and memory and attention ( p = 0.04) compared to non‐converters. Converters demonstrated higher Neuropsychiatric Inventory scores ( p = 0.0001), particularly in hyperactivity ( p = 0.003), reflecting greater behavioral disturbances. Conclusion Baseline impairments in cognitive function, memory, and neuropsychiatric profiles distinguish converters from non‐converters, highlighting overlaps between ADD/ADHD traits and prodromal FTD. These findings suggest shared neurobiological mechanisms and underscore the need for mutation‐specific studies to further explore the neurodevelopmental factors driving FTD progression.

We describe an unusual case of a woman in her 30s who had recently undergone Roux-en-Y gastric bypass and presented to the emergency department with a 6-week history of intractable nausea and vomiting, accompanied by progressively worsening bilateral leg weakness. Examination revealed persistent upbeat nystagmus, paraparesis, areflexia in the lower extremities, brisk reflexes in the upper extremities and diminished sensation across all modalities in lower limbs. Brain and spine MRIs were unremarkable, there was no nerve root enhancement. Laboratory tests revealed thiamine deficiency, with a level of 28 nmol/L (reference range: 70–108 nmol/L). No gangliocyte antibodies were detected. Cerebrospinal fluid study showed no albuminocytological dissociation. Electrodiagnostic studies showed evidence of lumbosacral polyradiculopathy. The patient was eventually diagnosed with thiamine deficiency-related acute nutritional axonal neuropathy and Wernicke’s encephalopathy. After aggressive thiamine supplementation and 8 weeks of physical rehabilitation, her leg strength improved, but she still requires assistance to ambulate.

ABSTRACT Objective To determine the test performance of cutaneous phosphorylated alpha‐synuclein (P‐SYN) in dementia with Lewy bodies (DLB), individuals with reduced Montreal Cognitive Assessment (MoCA) and healthy controls. Methods This is the first subgroup analysis of the Synuclein‐One study, a prospective, blinded study evaluating P‐SYN detection from skin biopsies in 218 subjects with a referral diagnosis of control ( N = 151) and DLB ( N = 67). All subjects completed detailed examinations, questionnaires, and had skin biopsies for detection of P‐SYN. DLB patients were included if meeting the 4th DLB consensus probable criteria. Control subjects, aged 40–99, had no history, examination findings, or symptoms suggestive of a synucleinopathy or neurodegenerative disease. An expert review panel, blinded to pathological data, determined the final diagnosis. Controls with reduced MoCA (MoCA < 26, N = 26) at screening were analyzed separately. Results After expert panel review, only 50/67 patients met consensus criteria for DLB, 26/151 controls had a reduced MoCA, and 120/151 controls had a normal MoCA. The proportions of subjects with cutaneous P‐SYN detected by skin biopsy were 96.0% (48 of 50) of the DLB group, 31% (8 of 26) of the controls with reduced MoCA, and 3.3% (4 of 120) of the controls with normal MoCA. Interpretation In this prospective, blinded, cross‐sectional study, a high proportion of subjects meeting clinical consensus criteria for DLB had P‐SYN detected in skin biopsies. Almost 1/3 of subjects with reduced MoCA testing also had P‐SYN detected. These results support a role for skin biopsy detection of P‐SYN in patients with DLB. Trial Registration NCT04700722

Abstract Background Bedside cognitive screening tools intend to reliably and efficiently detect cognitive impairment in research, clinical, and community settings. Black American (BA) and Hispanic/Latino (H/L) adults obtain lower performance on widely used screeners, largely driven by demographics and structural and social determinants of health (SSDoH). This study characterized the performance of the Montreal Cognitive Assessment (MoCA) performance in a cohort of cognitively normal ethnoracially diverse adults while considering cohort‐specific factors that contributed to misclassification of impairment. Method Cognitively normal BA and H/L participants completed a comprehensive neurological assessment, neuropsychological testing, and MRI and amyloid‐ and tau‐PET imaging as part of a longitudinal study of memory and aging at Mayo Clinic in Florida. Demographically adjusted MoCA cutoffs were applied to BA (MoCA ≤ 22) and WH/L (MoCA ≤ 24) subgroups. Hierarchical binary logistic regression assessed whether amyloid burden (Centiloid value) improved prediction of scoring below demographically adjusted MoCA cutoffs beyond demographic/SSDoH factors, including age, education, and Area Deprivation Index (ADI). Result Participants included 105 (47 WH/L, 58 BA/AA) cognitively normal adults (mean age = 64.71 years, SD = 8.91; 62.9% female) with average of 16.07 years of education (SD=2.35) and mild‐to‐moderate neighborhood disadvantage (mean ADI=47.60, SD=23.77). 40% of H/L participants (MoCA (≤ 24) and 17% of BA participants (MoCa ≤22) scored below demographically adjusted MoCA cut‐offs. For the H/L subgroup, the best fitting model included age, education, ADI, and amyloid burden ( R 2 = 0 .43, χ 2 = 10.98, p = 0.03). Age (OR=1.21, 95% CI: 0.986 – 1.487) and amyloid burden (OR = 0.83, 95% CI: 0.67 – 1.03) approached statistical significance as individual predictors ( p = 0.06, p = 0.09). In the BA/AA subgroup, the best fitting model included age, education and ADI only ( R 2 = 0.47, χ 2 = 9.06, p = 0.02), with education approaching significance as an individual predictor (OR=0.46, 95% CI: 0.21 – 1.01, p = 0.05). Conclusion Sociodemographic factors continued to drive low MoCA performance in cognitively normal individuals despite applying demographically adjusted cut‐off scores by subgroup. These factors differentially impacted performance among BA/AA and WH/L participants. Careful consideration of these factors is warranted to mitigate risk of overdiagnosing impairment based on cognitive screening across clinical and research settings.

Abstract Background African Americans (AA) are twice as likely to develop dementia than non‐Hispanic Whites but remain underrepresented in Alzheimer's Disease (AD) research. Recent studies have identified AA specific risk factors for AD. Therefore, targeted biomarkers and/or therapies may be needed to effectively treat AD in AA. In this study, we aimed to determine if genetic variants that show association with AD‐risk, plasma transcript or protein levels in AA, may serve as accurate and accessible AD biomarkers. Method In 189 clinically diagnosed AA AD cases and 183 AA cognitively unimpaired (CU) controls, we performed targeted DNA sequencing of 10 AD‐associated loci. Genetic variants at these loci were tested for association with corresponding plasma transcripts and total tau protein levels previously measured in this cohort using a custom nanoString panel and Simoa assays, respectively. Utilizing phased haplotypes (SHAPEIT4) from target sequencing, we inferred local ancestry (RFMix v2) using five superpopulations from the 1000 Genomes Project as anchors. Subsequently, we tested the association of each ancestry specific allelic dosages with endophenotypes using Tractor. In receiver operating characteristic (ROC) analyses, the most significant e/pQTLs were added sequentially to a base model that included age and sex to identify e/pQTLs that improved the accuracy to correctly classify AD cases and CU controls. Result Of the 5,112 variants that were tested, 70 were nominally associated with AD‐risk and with plasma transcript or protein levels. Seven of these 70 variants also showed nominally significant associations of AD‐risk and transcript levels with either African or East Asian local ancestry. ROC analysis of age, sex, 33 e/pQTLs in APOE , SORL1 , TLR4 , EPHA1 , ABCA7 , CLU , and CR1 , and plasma levels of APP, ABCA7, AKAP9, CD14, CLU, and APOE ‐ɛ4 dosage achieved 88.2% area under the curve to discriminate AD vs. CU, a 30.4% improvement over the base model that only included age and sex. Conclusion Plasma transcript levels and e/pQTLs are promising diagnostic biomarkers for AD that may improve accessibility and reduce costs for a more accurate diagnosis of AD.

Early-onset colorectal cancer (EOCRC) in people < 50 years of age has been rising globally, yet its causes remain unknown. Emerging evidence suggests that environmental factors, including exposure to micro-and nanoplastics (MNPs), may contribute to colorectal carcinogenesis. MNPs can enter the gastrointestinal tract through ingestion, translocate across the epithelial barrier via endocytosis or paracellular pathways, and interact directly with epithelial and immune cells. Once internalized, they may generate events associated with tumor initiation including oxidative stress, disruption of membrane integrity, pro-inflammatory signaling, and disruption of genomic and epigenomic stability. Patient-derived colorectal organoids offer a physiologically relevant and scalable 3D model that closely mimics the cellular architecture and genetic landscape of primary tumors. We highlight how organoid models can be leveraged to study the impact of MNPs on the key processes of inflammation, DNA damage, senescence, and epigenetic modifications. Furthermore, we discuss the application of organoid-based systems to model EOCRC driven by environmental exposures, including the integration of organoid platforms with high-throughput assays, omics profiling, and microfluidics to better capture MNP-induced pathogenic mechanisms. Altogether, colorectal organoids provide a powerful bridge between environmental plastic exposure and EOCRC etiology, offering a tractable platform to identify mechanistic pathways and potential biomarkers of early disease.