A neurodegenerative cellular stress response linked to dark microglia and toxic lipid secretion.

The brain's primary immune cells, microglia, are a leading causal cell type in Alzheimer's disease (AD). Yet, the mechanisms by which microglia can drive neurodegeneration remain unresolved. Here, we discover that a conserved stress signaling pathway, the integrated stress response (ISR), characterizes a microglia subset with neurodegenerative outcomes.

Neuroprotective effect of neuron-specific deletion of the C16 ceramide synthetic enzymes in an animal model of multiple sclerosis.

Ceramide C16 is a sphingolipid detected at high levels in several neurodegenerative disorders, including multiple sclerosis (MS). It can be generated de novo or from the hydrolysis of other sphingolipids, such as sphingomyelin or through the recycling of sphingosine, in what is known as the salvage pathway. While the myelin damage occurring in MS suggests the importance of the hydrolytic and salvage pathways, the growing interest on the importance of diet in demyelinating disorders, prompted us to investigate the involvement of de novo ceramide C16 synthesis on disease severity.

Inhibiting tau-induced elevated nSMase2 activity and ceramides is therapeutic in an Alzheimer's disease mouse model.

Background: Cognitive decline in Alzheimer's disease (AD) is associated with hyperphosphorylated tau (pTau) propagation between neurons along synaptically connected networks, in part via extracellular vesicles (EVs). EV biogenesis is triggered by ceramide enrichment at the plasma membrane from neutral sphingomyelinase2 (nSMase2)-mediated cleavage of sphingomyelin. We report, for the first time, that human tau expression elevates brain ceramides and nSMase2 activity.

Key regulator PNPLA8 drives phospholipid reprogramming induced proliferation and migration in triple-negative breast cancer.

Background: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and leads to the poorest patient outcomes despite surgery and chemotherapy treatment. Exploring new molecular mechanisms of TNBC that could lead to the development of novel molecular targets are critically important for improving therapeutic options for treating TNBC.

Methods: We sought to identify novel therapeutic targets in TNBC by combining genomic and functional studies with lipidomic analysis, which included mechanistic studies to elucidate the pathways that tie lipid profile to critical cancer cell properties.

Inhibiting tau-induced elevated nSMase2 activity and ceramides is therapeutic in murine Alzheimer's disease.

Background: Cognitive decline in Alzheimer's disease (AD) is associated with prion-like tau propagation between neurons along synaptically connected networks, in part via extracellular vesicles (EV). EV biogenesis is triggered by ceramide enrichment at the plasma membrane from neutral sphingomyelinase2(nSMase2)-mediated cleavage of sphingomyelin. We report, for the first time, that tau expression triggers an elevation in brain ceramides and nSMase2 activity.

Neutral sphingomyelinase 2 is required for HIV-1 maturation.

HIV-1 assembly occurs at the inner leaflet of the plasma membrane (PM) in highly ordered membrane microdomains. The size and stability of membrane microdomains is regulated by activity of the sphingomyelin hydrolase neutral sphingomyelinase 2 (nSMase2) that is localized primarily to the inner leaflet of the PM. In this study, we demonstrate that pharmacological inhibition or depletion of nSMase2 in HIV-1-producer cells results in a block in the processing of the major viral structural polyprotein Gag and the production of morphologically aberrant, immature HIV-1 particles with severely impaired infectivity.

Inhibition of neutral sphingomyelinase 2 impairs HIV-1 envelope formation and substantially delays or eliminates viral rebound.

Although HIV-1 Gag is known to drive viral assembly and budding, the precise mechanisms by which the lipid composition of the plasma membrane is remodeled during assembly are incompletely understood. Here, we provide evidence that the sphingomyelin hydrolase neutral sphingomyelinase 2 (nSMase2) interacts with HIV-1 Gag and through the hydrolysis of sphingomyelin creates ceramide that is necessary for proper formation of the viral envelope and viral maturation. Inhibition or depletion of nSMase2 resulted in the production of noninfectious HIV-1 virions with incomplete Gag lattices lacking condensed conical cores.

Neuronal deletion of nSMase2 reduces the production of Aβ and directly protects neurons.

Extracellular vesicles (EVs) have been proposed to regulate the deposition of Aβ. Multiple publications have shown that APP, amyloid processing enzymes and Aβ peptides are associated with EVs. However, very little Aβ is associated with EVs compared with the total amount Aβ present in human plasma, CSF, or supernatants from cultured neurons.

Dendrimer-Conjugated nSMase2 Inhibitor Reduces Tau Propagation in Mice.

Alzheimer's disease (AD) is characterized by the progressive accumulation of amyloid-β and hyperphosphorylated tau (pTau), which can spread throughout the brain via extracellular vesicles (EVs). Membrane ceramide enrichment regulated by the enzyme neutral sphingomyelinase 2 (nSMase2) is a critical component of at least one EV biogenesis pathway. Our group recently identified 2,6-Dimethoxy-4-(5-Phenyl-4-Thiophen-2-yl-1H-Imidazol-2-yl)-Phenol (DPTIP), the most potent (30 nM) and selective inhibitor of nSMase2 reported to date.

Oxysterol misbalance critically contributes to Wilson disease pathogenesis.

Wilson disease (WD) is a metabolic disorder caused by inactivation of the copper-transporting ATPase 2 (ATP7B) and copper (Cu) overload in tissues. Excess Cu causes oxidative stress and pathologic changes with poorly understood mechanistic connections. In mice with established liver disease, Cu overload activates the stress-sensitive transcription factor Nrf2 (nuclear factor erythroid-derived 2-like 2).

Immunometabolic Reprogramming in Response to HIV Infection Is Not Fully Normalized by Suppressive Antiretroviral Therapy.

Background: HIV infection results in immunometabolic reprogramming. While we are beginning to understand how this metabolic reprogramming regulates the immune response to HIV infection, we do not currently understand the impact of ART on immunometabolism in people with HIV (PWH).

Methods: Serum obtained from HIV-infected ( = 278) and geographically matched HIV seronegative control subjects ( = 300) from Rakai Uganda were used in this study.

Neutral sphingomyelinase 2 inhibition attenuates extracellular vesicle release and improves neurobehavioral deficits in murine HIV.

People living with HIV (PLH) have significantly higher rates of cognitive impairment (CI) and major depressive disorder (MDD) versus the general population. The enzyme neutral sphingomyelinase 2 (nSMase2) is involved in the biogenesis of ceramide and extracellular vesicles (EVs), both of which are dysregulated in PLH, CI, and MDD. Here we evaluated EcoHIV-infected mice for behavioral abnormalities relevant to depression and cognition deficits, and assessed the behavioral and biochemical effects of nSMase2 inhibition.

Fibroblast growth factor-21 improves insulin action in nonlactating ewes.

During metabolically demanding physiological states, ruminants and other mammals coordinate nutrient use among tissues by varying the set point of insulin action. This set point is regulated in part by metabolic hormones with some antagonizing (e.g.

Effects of serine palmitoyltransferase inhibition by myriocin in ad libitum-fed and nutrient-restricted ewes.

The fungal isolate myriocin inhibits serine palmitoyltransferase and de novo ceramide synthesis in rodents; however, the effects of myriocin on ceramide concentrations and metabolism have not been previously investigated in ruminants. In our study, 12 non-lactating crossbred ewes received an intravenous bolus of myriocin (0, 0.1, 0.

Characterization of the Plasma Lipidome in Dairy Cattle Transitioning from Gestation to Lactation: Identifying Novel Biomarkers of Metabolic Impairment.

The discovery of novel biomarkers for peripartal diseases in dairy cows can improve our understanding of normal and dysfunctional metabolism, and lead to nutritional interventions that improve health and milk production. Our objectives were to characterize the plasma lipidome and identify metabolites associated with common markers of metabolic disease in peripartal dairy cattle. Multiparous Holstein cows ( = 27) were enrolled 30 d prior to expected parturition.

Characterization of extracellular vesicles and synthetic nanoparticles with four orthogonal single-particle analysis platforms.

We compared four orthogonal technologies for sizing, counting, and phenotyping of extracellular vesicles (EVs) and synthetic particles. The platforms were: single-particle interferometric reflectance imaging sensing (SP-IRIS) with fluorescence, nanoparticle tracking analysis (NTA) with fluorescence, microfluidic resistive pulse sensing (MRPS), and nanoflow cytometry measurement (NFCM). EVs from the human T lymphocyte line H9 (high CD81, low CD63) and the promonocytic line U937 (low CD81, high CD63) were separated from culture conditioned medium (CCM) by differential ultracentrifugation (dUC) or a combination of ultrafiltration (UF) and size exclusion chromatography (SEC) and characterized by transmission electron microscopy (TEM) and Western blot (WB).

Nipping disease in the bud: nSMase2 inhibitors as therapeutics in extracellular vesicle-mediated diseases.

Extracellular vesicles (EVs) are indispensable mediators of intercellular communication, but they can also assume a nefarious role by ferrying pathological cargo that contributes to neurological, oncological, inflammatory, and infectious diseases. The canonical pathway for generating EVs involves the endosomal sorting complexes required for transport (ESCRT) machinery, but an alternative pathway is induced by the enrichment of lipid membrane ceramides generated by neutral sphingomyelinase 2 (nSMase2). Inhibition of nSMase2 has become an attractive therapeutic strategy for inhibiting EV biogenesis, and a growing number of small-molecule nSMase2 inhibitors have shown promising therapeutic activity in preclinical disease models.

Patterns and Predictors of Cognitive Function Among Virally Suppressed Women With HIV.

Cognitive impairment remains frequent and heterogeneous in presentation and severity among virally suppressed (VS) women with HIV (WWH). We identified cognitive profiles among 929 VS-WWH and 717 HIV-uninfected women from 11 Women's Interagency HIV Study sites at their first neuropsychological (NP) test battery completion comprised of: Hopkins Verbal Learning Test-Revised, Trail Making, Symbol Digit Modalities, Grooved Pegboard, Stroop, Letter/Animal Fluency, and Letter-Number Sequencing. Using 17 NP performance metrics (T-scores), we used Kohonen self-organizing maps to identify patterns of high-dimensional data by mapping participants to similar nodes based on T-scores and clustering those nodes.

Astrocytes deliver CK1 to neurons via extracellular vesicles in response to inflammation promoting the translation and amyloidogenic processing of APP.

Chronic inflammation is thought to contribute to the early pathogenesis of Alzheimer's disease (AD). However, the precise mechanism by which inflammatory cytokines promote the formation and deposition of Aβ remains unclear. Available data suggest that applications of inflammatory cytokines onto isolated neurons do not promote the formation of Aβ, suggesting an indirect mechanism of action.

White Matter Injury Is Associated with Reduced Manual Dexterity and Elevated Serum Ceramides in Subjects with Cerebral Small Vessel Disease.

Introduction: We have demonstrated that asymptomatic cerebral small vessel disease (cSVD) measured by white matter hyperintensity volume is associated with reduced manipulative manual dexterity on the Grooved Peg Board Test (GPBT) in middle-aged healthy individuals with a family history of early coronary artery disease. In this current study, we aim to identify the association of subcortical white matter microstructural impairment measured by diffusion tensor imaging, manual dexterity measured by GPBT and circulating serums ceramide, another marker for white matter injury. We hypothesize that lower regional fractional anisotropy (rFA) is associated with worse performance on GPBT and elevated serum ceramides in the same study population.

Palmitate and pyruvate carbon flux in response to choline and methionine in bovine neonatal hepatocytes.

Choline and methionine may serve unique functions to alter hepatic energy metabolism. Our objective was to trace carbon flux through pathways of oxidation and glucose metabolism in bovine hepatocytes exposed to increasing concentrations of choline chloride (CC) and D,L-methionine (DLM). Primary hepatocytes were isolated from 4 Holstein calves and maintained for 24 h before treatment with CC (0, 10, 100, 1000 μmol/L) and DLM (0, 100, 300 μmol/L) in a factorial design.