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Allergies are a very common pathology and their manifestations consist of a spectrum of presentations, ranging from minimal discomfort like a runny nose to lethal reactions like anaphylaxis and death. Meat allergy is not a very common form of allergy, even though there is a relatively high level of meat consumption. One of the rare forms of non-primate mammalian meat allergy is alpha-gal syndrome (AGS). It is related to IgE antibodies specific for galactose-α-1,3-galactose (α-Gal). It is triggered in sensitized individuals due to multiple bites of lone star tick bites (Amblyomma americanum). Here we present a 63-year-old male with a complaint of recurrent hives and tongue swelling, developed recently after traveling to Twinsburg, OH. There is no significant history of any allergic conditions. Vital signs were stable with a normal physical examination. The patient had normal routine labs including eosinophil count, thyroid-stimulating hormone (TSH), iron panel, and negative HIV. Allergy testing showed normal total IgE but increased levels of IgE for allergens like beef, lamb, and pork (18.4, 6.71, and 7.62 respectively) and greatly increased levels of IgE for alpha-gal (42.7). Sensitization to alpha-gal can cause delayed allergic symptoms upon consuming various non-primate mammalian types of meat, particularly beef, pork, and lamb. Conditions like AGS are rare and can be missed as an initial diagnosis in many patients. A high degree of vigilance is required to diagnose such conditions.
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Non-familial Alzheimer's disease (AD) occurring before 65 years of age is commonly referred to as early-onset Alzheimer's disease (EOAD) and constitutes ~ 5-6% of all AD cases (Mendez et al. in Continuum 25:34-51, 2019). While EOAD exhibits the same clinicopathological changes such as amyloid plaques, neurofibrillary tangles (NFTs), brain atrophy, and cognitive decline (Sirkis et al. in Mol Psychiatry 27:2674-88, 2022; Caldwell et al. in Mol Brain 15:83, 2022) as observed in the more prevalent late-onset AD (LOAD), EOAD patients tend to have more severe cognitive deficits, including visuospatial, language, and executive dysfunction (Sirkis et al. in Mol Psychiatry 27:2674-88, 2022). Patient-derived induced pluripotent stem cells (iPSCs) have been used to model and study penetrative, familial AD (FAD) mutations in APP, PSEN1, and PSEN2 (Valdes et al. in Research Square 1-30, 2022; Caldwell et al. in Sci Adv 6:1-16, 2020) but have been seldom used for sporadic forms of AD that display more heterogeneous disease mechanisms. In this study, we sought to characterize iPSC-derived neurons from EOAD patients via RNA sequencing. A modest difference in expression profiles between EOAD patients and non-demented control (NDC) subjects resulted in a limited number of differentially expressed genes (DEGs). Based on this analysis, we provide evidence that iPSC-derived neuron model systems, likely due to the loss of EOAD-associated epigenetic signatures arising from iPSC reprogramming, may not be ideal models for studying sporadic AD.
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Enfermedad de Alzheimer , Células Madre Pluripotentes Inducidas , Humanos , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Células Madre Pluripotentes Inducidas/patología , Mutación/genética , Neuronas/patologíaRESUMEN
Human fetal tissue and cells derived from fetal tissue are crucial for biomedical research. Fetal tissues and cells are used to study both normal development and developmental disorders. They are broadly applied in vaccine development and production. Further, research using cells from fetal tissue is instrumental for studying many infectious diseases, including a broad range of viruses. These widespread applications underscore the value of fetal tissue research and reflect an important point: cells derived from fetal tissues have capabilities that cells from other sources do not. In many cases, increased functionality of cells derived from fetal tissues arises from increased proliferative capacity, ability to survive in culture, and developmental potential that is attenuated in adult tissues. This review highlights important, representative applications of fetal tissue for science and medicine.
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Investigación Fetal , Feto , Adulto , HumanosRESUMEN
Pulmonary pleomorphic carcinoma (PPC) is a subtype of non-small cell lung cancer that is extremely rare and carries a poor prognosis due to its inadequate response to treatment. Patients that present with PPC often exhibit similar symptoms of other malignancies of the lung, making it hard for clinicians to distinguish between each type. However, cytology and gene mutation testing are two approaches that can aid physicians in an accurate and definitive diagnosis. We present a case of an 88-year-old male patient with a diagnosis of pulmonary pleomorphic carcinoma after experiencing recurrent sanguineous pleural effusions. The patient had no smoking history but did have a history of asbestos exposure and pulmonary fibrosis. The patient underwent thoracotomy with pleurodesis and analysis of the surgical pleural biopsy specimen stained positive for markers indicative of PPC. The pathology report was also consistent with the associated cell morphology. Lung cancer is the leading cause of mortality due to cancer in the United States, and exposure to certain substances contributes to the development of these poorly treatable lung malignancies. Smoking and asbestos exposure are well known to act synergistically with each other as risk factors in developing these lung malignancies. In addition to clinical suspicion, screening for these risk factors with laboratory values and imaging is important to diagnose these rare cases of lung malignancies.
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Advances in the field of human stem cells are often a source of public and ethical controversy. Researchers must frequently balance diverse societal perspectives on questions of morality with the pursuit of medical therapeutics and innovation. Recent developments in brain organoids make this challenge even more acute. Brain organoids are a new class of brain surrogate generated from human pluripotent stem cells (hPSCs). They have gained traction as a model for studying the intricacies of the human brain by using advancements in stem cell biology to recapitulate aspects of the developing human brain in vitro. However, recent observation of neural oscillations spontaneously emerging from these organoids raises the question of whether brain organoids are or could become conscious. At the same time, brain organoids offer a potentially unique opportunity to scientifically understand consciousness. To address these issues, experimental biologists, philosophers, and ethicists united to discuss the possibility of consciousness in human brain organoids and the consequent ethical and moral implications.
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Estado de Conciencia , Células Madre Pluripotentes , Humanos , Condición Moral , Encéfalo , OrganoidesRESUMEN
Alzheimer's disease (AD) is a common neurodegenerative disorder and a mechanistically complex disease. For the last decade, human models of AD using induced pluripotent stem cells (iPSCs) have emerged as a powerful way to understand disease pathogenesis in relevant human cell types. In this review, we summarize the state of the field and how this technology can apply to studies of both familial and sporadic studies of AD. We discuss patient-derived iPSCs, genome editing, differentiation of neural cell types, and three-dimensional organoids, and speculate on the future of this type of work for increasing our understanding of, and improving therapeutic development for, this devastating disease.
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Enfermedad de Alzheimer , Células Madre Pluripotentes Inducidas , Humanos , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Neuronas/patología , Neuroglía/patología , Organoides/patologíaRESUMEN
Traumatic brain injury (TBI) results in disrupted brain function following impact from an external force and is a risk factor for sporadic Alzheimer's disease (AD). Although neurologic symptoms triggered by mild traumatic brain injuries (mTBI), the most common form of TBI, typically resolve rapidly, even an isolated mTBI event can increase the risk to develop AD. Aberrant accumulation of amyloid ß peptide (Aß), a cleaved fragment of amyloid precursor protein (APP), is a key pathologic outcome designating the progression of AD following mTBI and has also been linked to impaired axonal transport. However, relationships among mTBI, amyloidogenesis, and axonal transport remain unclear, in part because of the dearth of human models to study the neuronal response following mTBI. Here, we implemented a custom-microfabricated device to deform neurons derived from human-induced pluripotent stem cells, derived from a cognitively unimpaired male individual, to mimic the mild stretch experienced by neurons during mTBI. Although no cell lethality or cytoskeletal disruptions were observed, mild stretch was sufficient to stimulate rapid amyloidogenic processing of APP. This processing led to abrupt cessation of APP axonal transport and progressive formation of aberrant axonal accumulations that contained APP, its processing machinery, and amyloidogenic fragments. Consistent with this sequence of events, stretch-induced defects were abrogated by reducing amyloidogenesis either pharmacologically or genetically. In sum, we have uncovered a novel and manipulable stretch-induced amyloidogenic pathway directly responsible for APP axonal transport dysregulation. Our findings may help to understand and ultimately mitigate the risk of developing AD following mTBI.SIGNIFICANCE STATEMENT Mild traumatic brain injury is a risk factor for sporadic Alzheimer's disease (AD). Increased amyloid ß peptide generation after injury may drive this risk. Here, by using a custom-built device to impose mild stretch to human neurons, we found that stretch triggers amyloid precursor protein (APP) cleavage, and thus amyloid ß peptide generation, consequently disrupting APP axonal transport. Compellingly, protecting APP from cleavage was sufficient to spare axonal transport dysregulation and the consequent aberrant axonal accumulation of APP. Supporting such protective mechanism, the expression of the AD-protective APPA673T genetic variant conferred protection against stretch-induced APP axonal transport phenotypes. Our data reveal potential subcellular pathways contributing to the development of AD-associated phenotypes following mild traumatic brain injury, and putative strategies for intervening in these pathways.
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Precursor de Proteína beta-Amiloide/metabolismo , Transporte Axonal/fisiología , Neuronas/metabolismo , Neuronas/patología , Enfermedad de Alzheimer/etiología , Conmoción Encefálica/complicaciones , Conmoción Encefálica/metabolismo , Conmoción Encefálica/patología , Técnicas de Cultivo de Célula/métodos , Humanos , Células Madre Pluripotentes Inducidas , MasculinoRESUMEN
Sporadic Alzheimer's disease (AD) exclusively affects elderly people. Using direct conversion of AD patient fibroblasts into induced neurons (iNs), we generated an age-equivalent neuronal model. AD patient-derived iNs exhibit strong neuronal transcriptome signatures characterized by downregulation of mature neuronal properties and upregulation of immature and progenitor-like signaling pathways. Mapping iNs to longitudinal neuronal differentiation trajectory data demonstrated that AD iNs reflect a hypo-mature neuronal identity characterized by markers of stress, cell cycle, and de-differentiation. Epigenetic landscape profiling revealed an underlying aberrant neuronal state that shares similarities with malignant transformation and age-dependent epigenetic erosion. To probe for the involvement of aging, we generated rejuvenated iPSC-derived neurons that showed no significant disease-related transcriptome signatures, a feature that is consistent with epigenetic clock and brain ontogenesis mapping, which indicate that fibroblast-derived iNs more closely reflect old adult brain stages. Our findings identify AD-related neuronal changes as age-dependent cellular programs that impair neuronal identity.
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Enfermedad de Alzheimer , Células Madre Pluripotentes Inducidas , Anciano , Envejecimiento , Fibroblastos , Humanos , NeuronasRESUMEN
Recent data establish multiple defects in endocytic functions as early events initiating various neurodegenerative disorders, including Alzheimer's disease (AD). The genetic landscape resulting from genome-wide association studies (GWAS) reveals changes in post-endocytic trafficking of amyloid precursor protein (APP) in neurons leading to an increase in amyloidogenic processing, deficits in amyloid beta (Aß) clearance, increases in intracellular Aß, and other endosomal pathogenic phenotypes. Multiple genetic factors regulate each segment of endosomal and post-endosomal trafficking. Intriguingly, several studies indicate endosomal dysfunctions preceding Aß pathology and tau phosphorylation. In this chapter we highlight the role of various GWAS-identified endosomal and post-endosomal gene products in initiating AD pathologies. We also summarize the functions of various genetic modifiers of post-endocytic trafficking of APP that may work as targets for therapeutic intervention in AD.
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Enfermedad de Alzheimer , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Endosomas/metabolismo , Estudio de Asociación del Genoma Completo , Humanos , Transporte de ProteínasRESUMEN
Amyloid beta (Aß) is a major component of amyloid plaques, which are a key pathological hallmark found in the brains of Alzheimer's disease (AD) patients. We show that statins are effective at reducing Aß in human neurons from nondemented control subjects, as well as subjects with familial AD and sporadic AD. Aß is derived from amyloid precursor protein (APP) through sequential proteolytic cleavage by BACE1 and γ-secretase. While previous studies have shown that cholesterol metabolism regulates APP processing to Aß, the mechanism is not well understood. We used iPSC-derived neurons and bimolecular fluorescence complementation assays in transfected cells to elucidate how altering cholesterol metabolism influences APP processing. Altering cholesterol metabolism using statins decreased the generation of sAPPß and increased levels of full-length APP (flAPP), indicative of reduced processing of APP by BACE1. We further show that statins decrease flAPP interaction with BACE1 and enhance APP dimerization. Additionally, statin-induced changes in APP dimerization and APP-BACE1 are dependent on cholesterol binding to APP. Our data indicate that statins reduce Aß production by decreasing BACE1 interaction with flAPP and suggest that this process may be regulated through competition between APP dimerization and APP cholesterol binding.
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Precursor de Proteína beta-Amiloide/metabolismo , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Neuronas/metabolismo , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Péptidos beta-Amiloides/fisiología , Precursor de Proteína beta-Amiloide/efectos de los fármacos , Precursor de Proteína beta-Amiloide/fisiología , Ácido Aspártico Endopeptidasas/metabolismo , Colesterol/metabolismo , Dimerización , Células HEK293 , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Neuronas/efectos de los fármacos , Neuronas/fisiología , Unión ProteicaRESUMEN
The global epidemic of Alzheimer disease (AD) is worsening, and no approved treatment can revert or arrest progression of this disease. AD pathology is characterized by the accumulation of amyloid-ß (Aß) plaques and tau neurofibrillary tangles in the brain. Genetic data, as well as autopsy and neuroimaging studies in patients with AD, indicate that Aß plaque deposition precedes cortical tau pathology. Because Aß accumulation has been considered the initial insult that drives both the accumulation of tau pathology and tau-mediated neurodegeneration in AD, the development of AD therapeutics has focused mostly on removing Aß from the brain. However, striking preclinical evidence from AD mouse models and patient-derived human induced pluripotent stem cell models indicates that tau pathology can progress independently of Aß accumulation and arises downstream of genetic risk factors for AD and aberrant metabolic pathways. This Review outlines novel insights from preclinical research that implicate apolipoprotein E, the endocytic system, cholesterol metabolism and microglial activation as Aß-independent regulators of tau pathology. These factors are discussed in the context of emerging findings from clinical pathology, functional neuroimaging and other approaches in humans. Finally, we discuss the implications of these new insights for current Aß-targeted strategies and highlight the emergence of novel therapeutic strategies that target processes upstream of both Aß and tau.
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Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/metabolismo , Proteínas tau/metabolismo , Enfermedad de Alzheimer/terapia , Animales , Apolipoproteínas E/metabolismo , Colesterol/metabolismo , Endocitosis , Humanos , Microglía/metabolismo , Placa Amiloide/patologíaRESUMEN
In the mammalian genome, the clustered protocadherin (cPCDH) locus provides a paradigm for stochastic gene expression with the potential to generate a unique cPCDH combination in every neuron. Here we report a chromatin-based mechanism that emerges during the transition from the naive to the primed states of cell pluripotency and reduces, by orders of magnitude, the combinatorial potential in the human cPCDH locus. This mechanism selectively increases the frequency of stochastic selection of a small subset of cPCDH genes after neuronal differentiation in monolayers, 10-month-old cortical organoids and engrafted cells in the spinal cords of rats. Signs of these frequent selections can be observed in the brain throughout fetal development and disappear after birth, except in conditions of delayed maturation such as Down's syndrome. We therefore propose that a pattern of limited cPCDH-gene expression diversity is maintained while human neurons still retain fetal-like levels of maturation.
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Cadherinas/genética , Cromatina/genética , Síndrome de Down/patología , Células Madre Pluripotentes Inducidas/citología , Neuronas/fisiología , Adulto , Animales , Astrocitos/citología , Astrocitos/fisiología , Encéfalo/citología , Encéfalo/embriología , Diferenciación Celular , Línea Celular , Síndrome de Down/genética , Regulación de la Expresión Génica , Histonas/genética , Humanos , Células Madre Pluripotentes Inducidas/fisiología , Células Madre Pluripotentes Inducidas/trasplante , Ratones , Persona de Mediana Edad , Neuronas/citología , Regiones Promotoras Genéticas , Ratas , Análisis de la Célula Individual , Médula Espinal/citología , Médula Espinal/trasplante , Trasplante HeterólogoRESUMEN
Genetic, epidemiologic, and biochemical evidence suggests that predisposition to Alzheimer's disease (AD) may arise from altered cholesterol metabolism, although the molecular pathways that may link cholesterol to AD phenotypes are only partially understood. Here, we perform a phenotypic screen for pTau accumulation in AD-patient iPSC-derived neurons and identify cholesteryl esters (CE), the storage product of excess cholesterol, as upstream regulators of Tau early during AD development. Using isogenic induced pluripotent stem cell (iPSC) lines carrying mutations in the cholesterol-binding domain of APP or APP null alleles, we found that while CE also regulate Aß secretion, the effects of CE on Tau and Aß are mediated by independent pathways. Efficacy and toxicity screening in iPSC-derived astrocytes and neurons showed that allosteric activation of CYP46A1 lowers CE specifically in neurons and is well tolerated by astrocytes. These data reveal that CE independently regulate Tau and Aß and identify a druggable CYP46A1-CE-Tau axis in AD.
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Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Colesterol/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Neuronas/metabolismo , Proteínas tau/metabolismo , Enfermedad de Alzheimer/patología , Animales , Células Cultivadas , Ratones , Ratones Endogámicos C57BLRESUMEN
Mounting evidence suggests that alterations in cholesterol homeostasis are involved in Alzheimer's disease (AD) pathogenesis. Amyloid precursor protein (APP) or multiple fragments generated by proteolytic processing of APP have previously been implicated in the regulation of cholesterol metabolism. However, the physiological function of APP in regulating lipoprotein homeostasis in astrocytes, which are responsible for de novo cholesterol biosynthesis and regulation in the brain, remains unclear. To address this, here we used CRISPR/Cas9 genome editing to generate isogenic APP-knockout (KO) human induced pluripotent stem cells (hiPSCs) and differentiated them into human astrocytes. We found that APP-KO astrocytes have reduced cholesterol and elevated levels of sterol regulatory element-binding protein (SREBP) target gene transcripts and proteins, which were both downstream consequences of reduced lipoprotein endocytosis. To elucidate which APP fragments regulate cholesterol homeostasis and to examine whether familial AD mutations in APP affect lipoprotein metabolism, we analyzed an isogenic allelic series harboring the APP Swedish and APP V717F variants. Only astrocytes homozygous for the APP Swedish (APPSwe/Swe) mutation, which had reduced full-length APP (FL APP) due to increased ß-secretase cleavage, recapitulated the APP-KO phenotypes. Astrocytic internalization of ß-amyloid (Aß), another ligand for low-density lipoprotein (LDL) receptors, was also impaired in APP-KO and APPSwe/Swe astrocytes. Finally, impairing cleavage of FL APP through ß-secretase inhibition in APPSwe/Swe astrocytes reversed the LDL and Aß endocytosis defects. In conclusion, FL APP is involved in the endocytosis of LDL receptor ligands and is required for proper cholesterol homeostasis and Aß clearance in human astrocytes.
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Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Astrocitos/metabolismo , Colesterol/metabolismo , Lipoproteínas/metabolismo , Precursor de Proteína beta-Amiloide/genética , Astrocitos/citología , Sistemas CRISPR-Cas , Línea Celular , Endocitosis , Humanos , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Receptores de LDL/metabolismo , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismoRESUMEN
Developing effective therapeutics for complex diseases such as late-onset, sporadic Alzheimer's disease (SAD) is difficult due to genetic and environmental heterogeneity in the human population and the limitations of existing animal models. Here, we used hiPSC-derived neurons to test a compound that stabilizes the retromer, a highly conserved multiprotein assembly that plays a pivotal role in trafficking molecules through the endosomal network. Using this human-specific system, we have confirmed previous data generated in murine models and show that retromer stabilization has a potentially beneficial effect on amyloid beta generation from human stem cell-derived neurons. We further demonstrate that manipulation of retromer complex levels within neurons affects pathogenic TAU phosphorylation in an amyloid-independent manner. Taken together, our work demonstrates that retromer stabilization is a promising candidate for therapeutic development in AD and highlights the advantages of testing novel compounds in a human-specific, neuronal system.