Purpose:Perioperative exposure to the volatile anesthetic isoflurane (ISO) has been associated with cognitive and olfactory deficits and may increase the risk of Alzheimer's disease (AD). Apolipoprotein E4 (APOE4), the strongest genetic risk factor for AD, contributes to disease pathogenesis through disrupted lipid homeostasis. However, whether and how isoflurane interacts with APOE genotype to influence neurological vulnerability remains unclear. Methods:Young adult, presymptomatic humanized APOE4 and APOE3 knock-in mice underwent laparotomy under 2 h of isoflurane anesthesia. Microglia and astrocytes were isolated from the olfactory bulb (OB) and hippocampus (HI) by magnetic-activated cell sorting. Lipid composition, transcriptional responses, and functional outcomes were assessed using lipidomic, bulk RNA-seq, and longitudinal behavioral testing. In vivo and ex vivo electrophysiological recordings evaluated neuronal excitability and synaptic transmission in both regions. Results:By day 7 post-anesthesia, cell type-specific lipidomic profiling of both OB and HI revealed more pronounced lipid perturbations in microglia and astrocytes from APOE4/ISO mice than from APOE3 mice, characterized by elevated free fatty acids, increased lipid peroxidation, triglyceride depletion, and reduced hippocampal hexosylceramides and cardiolipins. Electrophysiological recordings showed greater olfactory circuit dysfunction in APOE4/ISO mice, accompanied by persistent odor memory deficits, transient olfactory sensitivity loss, early motor coordination impairments, and delayed cognitive deficits. RNA sequencing of the OB identified downregulated lipid metabolism and atherosclerosis-related pathways. Conclusion:These findings establish a mechanistic link between APOE4-dependent glial lipid dysregulation, olfactory circuit dysfunction, and delayed cognitive impairment following isoflurane anesthesia and surgery, highlighting lipid homeostasis as a potential therapeutic target.

Oligonucleotide therapeutics are emerging as a promising modality for targeting disease-associated RNAs. Phosphorothioate (PS)-containing oligonucleotides have gained prominence due to their enhanced stability and pharmacodynamic properties. However, current manufacturing practices afford a mixture of Rp and Sp stereoisomers, and this distribution has been linked to changes in product efficacy. Understanding the sensitivity of analytical methods to changes in this quality attribute has therefore become critically important. Here, we used a suite of analytical techniques-ultraviolet (UV) thermal denaturation, circular dichroism (CD), and nuclear magnetic resonance (NMR) spectroscopy-to evaluate the PS diastereomer distribution using Tegsedi, a Food and Drug Administration-approved PS-containing antisense oligonucleotide, and with other synthetic inotersen samples having varied PS diastereomer distributions. While UV and CD techniques showed limited sensitivity, NMR excelled in detecting small changes in the PS diastereomer distribution. The univariate metric of 31P integration was shown to be insufficient for this quality metric evaluation; application of principal component analysis to both 1D 31P and 2D 1H,13C spectra revealed distinct PS changes that arose from the different activators used during manufacturing. This comprehensive evaluation highlights the necessity of advanced analytical techniques in ensuring the quality and consistency of PS-containing oligonucleotide therapeutics.

Enveloped viruses are significant zoonotic disease threats with the potential to cause global pandemics. We identified a class of small-molecule sulfur-containing antiviral compounds (XM series) that broadly inhibit enveloped viruses. Multidisciplinary approaches revealed that XM compounds alter the viral membrane lipid chemical composition, enhance membrane order within the hydrophobic bilayer, and increase membrane phase transition temperatures. This mechanism inhibits membrane fusion and viral entry, while leaving the viral glycoproteins and genomes largely unaffected. Leveraging these unique properties, we develop a proof-of-concept whole inactivated influenza virus (IIV) vaccine using XM-01 (XM-01-IIV). In a mouse model, XM-01-IIV elicit significantly enhanced neutralizing antibody responses against hemagglutinin and neuraminidase compared to traditional paraformaldehyde-inactivated vaccines. Further, XM-01-IIV reduces morbidity and mortality following influenza challenge, achieving protection comparable to live virus vaccination. This promising class of broadly acting antivirals can be highly impactful in the development of highly potent inactivated vaccines for enveloped viruses.

The brain is a lipid-rich organ that experiences rapid growth and development after birth in a period hallmarked by extensive lipid synthesis. We still lack a fundamental understanding of lipid metabolism during this critical time of brain development and how these dynamics occur in infants born extremely preterm (<28 weeks of gestation) suffering from brain injuries. Using an established model of neonatal brain injury due to intermittent hypoxemia, we recapitulate hippocampal-dependent cognitive impairments and examine the extent of changes in the brain’s lipid profile. Our results show changes in hippocampal lipid composition and abnormal fatty acid profile. Furthermore, we provide evidence of an increase in mitochondrial fatty acid β-oxidation, a process that is not classically thought of occurring in the developing brain. We find that a specific alternative fuel, acetate, spares fatty acids from mitochondrial β-oxidation. Here, we show that treatment with acetate in vivo in the form of glycerol-triacetate promotes functional recovery and restores hippocampal fatty acid profile after neonatal brain injury. Neonatal brain injury from intermittent hypoxemia increases fatty acid oxidation and causes long-term changes in hippocampal lipid profile. Here authors demonstrate oral treatment with glycerol-triacetate restores lipid fatty acid profile and promotes functional recovery.

Ether-glycerophospholipids (ether-GPs), the ether bond- (- O -) containing glycerophospholipids, are major components of the brain lipidome. Ether-GPs play a crucial role in regulating neuronal function, and their deficiency has been implicated in many neurodegenerative diseases. However, how they are affected after traumatic brain injury (TBI) is not known. Our data demonstrate a significant decrease in ether-GPs abundance in the mouse cortex following controlled cortical impact (CCI)-induced TBI. This is at least in part due to the impairment of peroxisomal ether-GP synthesis in the mouse brain after TBI. We detected dysregulation of peroxisomal ether-GPs synthesizing enzymes - glyceronephosphate-O-acyltransferase (GNPAT) and alkylglycerone phosphate synthase (AGPS) in the injured mouse brains. Our data demonstrate a significant decline in GNPAT level in the peroxisomal fraction and a marked accumulation of AGPS in the cytosol of mouse cortices after TBI. To restore the ether-GP level in the injured brain, we treated TBI mice with an ether-GP precursor, 1-O-octadecylglycerol (OAG), to bypass the peroxisomal ether-GPs synthesizing steps. OAG partially restored the levels of several ether-GPs, attenuated inflammatory cytokine expression, and improved their functional recovery after TBI. Taken together, our data demonstrate that the decline in ether-GPs abundance after TBI is at least in part due to the impairment in peroxisomal ether-GPs synthesis and that restoration of ether-GPs by OAG treatment can improve TBI outcomes.

Motivated by promising clinical trial data for the combination of the histone deacetylase 6 (HDAC6) inhibitor ricolinostat with the proteasome inhibitor bortezomib in relapsed/refractory multiple myeloma (MM) patients, we engineered dual HDAC6/proteasome inhibitors. FDA-approved HDAC inhibitors suffer from off-target effects, which have been attributed, in part, to their lack of HDAC isoform selectivity. Furthermore, they are potentially mutagenic, because of their indispensable hydroxamic acid zinc-binding groups (ZBGs). Deploying the HDAC6-selective phenyl-4-hydroxamic acid motif, and O-carbamoylated hydroxamates as hydroxamic acid surrogates, then grafting to the electrophilic boronic acid warhead of bortezomib/ixazomib, we discovered several dual HDAC6/proteasome inhibitors that were potent in cell-free assays, inhibiting the chymotrypsin-like (CL) proteasomal activity on par with that of bortezomib, and many compounds demonstrated selectivity for HDAC6 over HDAC1 as predicted. Moreover, several dual HDAC6/proteasome inhibitors were submicromolar inhibitors of MM cell growth. Of particular interest, AMC-3-030 with an O-(N-phenylcarbamoyl)-hydroxamate ZBG emerged as an exciting lead for further studies.

Synthetic oligonucleotide therapeutics represent a rapidly advancing class of drugs that target RNA to modulate gene expression. The phosphorothioate modification to the nucleic acid backbone is routinely used to increase resistance to enzymatic degradation and improve the pharmacological profile. Each phosphorothioate modification creates a stereogenic center, leading to the formation of diastereomers at every modified linkage. This results in a final drug product containing a complex and heterogenous mixture of diastereomers. With the increasing regulatory approval of synthetic oligonucleotide drug products, there is a pressing need to develop analytical methods that can characterize their diastereomer composition. We detail the use of four liquid chromatography methods complemented by 31P NMR to characterize the diastereomer composition of fully phosphorothioated short (2- and 5-mers) and full-length (20-mers) oligonucleotide sequences. We also assessed the effect of how specific chemical activators influenced the diastereomer composition in these synthetic sequences. Our data showed that the use of multiple liquid chromatography methods augmented by 31P NMR provided complementary and additional insight into the diastereomer composition of phosphorothioate-linked oligonucleotides. Further, our data also indicated that the chemical activator substantially influenced the diastereomer content but other important factors including the overall chemical synthesis process and sequence specific nucleobases and modifications play an important role as well.

Polymeric nanoparticles (NPs) are promising tools used for immunomodulation and drug delivery in various disease contexts. The interaction between NP surfaces and plasma-resident biomolecules results in the formation of a biomolecular corona, which varies patient-to-patient and as a function of disease state. This study investigates how the progression of acute systemic inflammatory disease influences NP corona compositions and the corresponding effects on innate immune cell interactions, phenotypes, and cytokine responses. NP coronas alter cell associations in a disease-dependent manner, induce differential co-stimulatory and co-inhibitory molecule expression, and influence cytokine release. Integrated multi-omics analysis of proteomics, lipidomics, metabolomics, and cytokine datasets highlight a set of differentially enriched TLR4 ligands that correlate with dynamic NP corona-mediated immune activation. Pharmacological inhibition and genetic knockout studies validate that NP coronas mediate this response through TLR4/MyD88/NF-κB signaling. Our findings illuminate the personalized nature of corona formation under a dynamic inflammatory condition and its impact on NP-mediated immune activation profiles and inflammation, suggesting that disease progression-related alterations in plasma composition can manifest in the corona to cause unintended toxicity and altered therapeutic efficacy.

Mammalian injury responses are predominantly characterized by fibrosis and scarring rather than functional regeneration. This limited regenerative capacity in mammals could reflect a loss of proregeneration programs or active suppression by genes functioning akin to tumor suppressors. To uncover programs governing regeneration in mammals, we screened transcripts in human participants following laser rejuvenation treatment and compared them with mice with enhanced wound-induced hair neogenesis (WIHN), a rare example of mammalian organogenesis. We found that Rnasel-/-mice exhibit an increased regenerative capacity, with elevated WIHN through enhanced IL-36 alpha. Consistent with RNase L's known role to stimulate caspase-1, we found that pharmacologic inhibition of caspases promoted regeneration in an IL-36-dependent manner in multiple epithelial tissues. We identified a negative feedback loop, where RNase L-activated caspase-1 restrains the proregenerative dsRNA-TLR3 signaling cascade through the cleavage of toll-like adaptor protein TRIF. Through integrated single-cell RNA-seq and spatial transcriptomic profiling, we confirmed OAS & IL-36 genes to be highly expressed at the site of wounding and elevated in Rnasel-/- mouse wounds. This work suggests that RNase L functions as a regeneration repressor gene, in a functional trade off that tempers immune hyperactivation during viral infection at the cost of inhibiting regeneration.

CNS has an overall higher level of lipids than all tissues except adipose and contains up to 25% of total body cholesterol. Recent data demonstrate a complex crosstalk between lipid metabolism and inflammation, suggesting potential contribution of the lipid-rich brain environment to neuroinflammation. While recent data support the importance of brain lipid environment to inflammatory changes observed in age related chronic neurodegenerative diseases, in vivo interactions between lipid environment, lipid metabolism and neuroinflammation in acute brain disease and injury remain poorly understood. Here we utilize a mouse model of traumatic brain injury (TBI) to demonstrate that acute neurotrauma leads to widespread lipid metabolism reprograming in all microglial and brain associated and infiltrating monocyte populations. Additionally, we identify unique microglial and monocyte populations with higher degree of lipid metabolism reprograming and pronounced accumulation of neutral storage lipids, including cholesteryl esters and triglycerides. These lipids accumulate not only in lipid droplets but also in the microglial and monocyte lysosomes and are associated with lysosomal dysfunction and inhibition of autophagy after TBI. Our data indicate that lipid accumulation in these cells is the result of altered lipid handling rather than lipid synthesis and is triggered by phagocytosis of lipid-rich myelin debris generated after TBI. Finally, we use mice with autophagy defects in microglia and monocytes to demonstrate that further inhibition of autophagy leads to more pronounced lipid metabolism reprograming and exacerbated cellular lipid accumulation. Our data suggest a pathological feedback loop, where lipid phagocytosis causes inhibition of autophagy-lysosomal function, which in turn exacerbates cellular lipid retention, reprograming and inflammation.

Recent data indicate that lipid composition has profound influence on the brain function and that changes in lipid homeostasis affect brain aging and predisposition to neurodegenerative diseases. Lipids dynamically reside in multiple intracellular locations and their organellar distribution is important for specific interactions and biological function. During brain aging lipid changes have been specifically noted in lysosomes, but the identity of the accumulated lipids, their interactions with other biomolecules such as proteins, and their functional relevance have not been characterized. We used mass spectrometry (MS) to assess longitudinal changes in the lipidome and proteome of lysosomes isolated from the mouse cortex, from the age of 3- to 24-months. Our statistical and machine learning analyses identified two factors demonstrating predictive power for age and differences in both lipids and proteins. Of these, factor 1 was the best predictor of sample age. Factor 1 lipids with the highest feature importance included multiple species of hexosylceramides (HexCer) and their sulfonated derivatives, sulfatides (SHexCer), all of which increased with age. Increased factor 1 proteins included myelin proteins, select sphingolipid catabolism enzymes and proteins associated with lysosomal storage diseases. Our analyses suggested that mechanisms underlying factor 1 encompass the combination of an age-dependent increase in lysosomal delivery of myelin components and alterations in lysosomal sphingolipid catabolism favoring degradation of sphingomyelin over HexCer. The overall age-related lysosomal changes resembled those observed in lysosomal storage diseases, particularly Gaucher disease, where accumulation of HexCer species is associated with lysosomal dysfunction. To corroborate factor 1 predictions, we employed a combination of biochemical, imaging and flow cytometry approaches, which confirmed alterations in sphingolipid catabolism and lysosomal accumulation of myelin components. These changes were associated with age-related alteration in lysosomal morphology, lysosomal dysfunction and inhibition of autophagy in both neurons and microglia. Our findings indicate that factors contributing to lysosomal aging resemble those observed in lysosomal storage diseases and underscore the significance of organelle-specific analyses for dissecting mechanisms contributing to brain aging. ### Competing Interest Statement The authors have declared no competing interest. NIH Common Fund, https://ror.org/001d55×84, R01NS115876, R33AG076858, R56AG081262 University of Maryland System, AIM-HI Challenge Award

Plant-derived lipid nanoparticles (PDNPs) are nano-sized particles isolated from various edible plants that contain bioactive components involved in regulating biological responses. Here, we isolated maca-derived lipid nanoparticles (MDNPs) from Lepidium meyenii Walp (maca), evaluated their therapeutic effects using two representative lethal models of sepsis, and determined their multimodal anti-inflammatory mechanism that relied on broad sequestration and neutralization of multiple pro-inflammatory cytokines and acute phase proteins (APPs) through formation of a protein corona. Lipidomics of MDNPs revealed triacylglycerols and phytoceramides as major constituents. In vitro studies showed that MDNPs were non-toxic, reduced macrophage activation, and sequestered lipopolysaccharide (LPS)-induced pro-inflammatory cytokines, while mitigating nuclear factor kappa B (NF-κB) activity. In a pre-established LPS-induced endotoxemia model, MDNP treatment significantly reduced systemic pro-inflammatory cytokines, reduced organ damage, and increased survival. Untargeted proteomics and bioinformatics analysis identified an enrichment in APPs present in MDNP protein coronas and corresponding inflammatory pathways modulated. The efficacy of MDNPs were further tested using a lethal polymicrobial sepsis model, where treatment significantly improved survival even in the absence of antibiotics. This study identifies MDNPs as an effective strategy capable of inducing potent anti-inflammatory responses, offering significant therapeutic potential for diseases such as sepsis, while informing the future design of synthetic lipid nanoparticles.

Transient events during development can exert long-lasting effects on organismal lifespan. Here we demonstrate that exposure of Caenorhabditis elegans to reactive oxygen species during development protects against amyloid-induced proteotoxicity later in life. We show that this protection is initiated by the inactivation of the redox-sensitive H3K4me3-depositing COMPASS complex and conferred by a substantial increase in the heat-shock-independent activity of heat shock factor 1 (HSF-1), a longevity factor known to act predominantly during C. elegans development. We show that depletion of HSF-1 leads to marked rearrangements of the organismal lipid landscape and a significant decrease in mitochondrial β-oxidation and that both lipid and metabolic changes contribute to the protective effects of HSF-1 against amyloid toxicity. Together, these findings link developmental changes in the histone landscape, HSF-1 activity and lipid metabolism to protection against age-associated amyloid toxicities later in life.

Propionic acid links the oxidation of branched-chain amino acids and odd-chain fatty acids to the TCA cycle. Gut microbes ferment complex fiber remnants, generating high concentrations of short chain fatty acids, acetate, propionate and butyrate, which are shared with the host as fuel sources. Analysis of vitamin B12-dependent propionate utilization in skin biopsy samples has been used to characterize and diagnose underlying inborn errors of cobalamin (or B12) metabolism. In these cells, the B12-dependent enzyme, methylmalonyl-CoA mutase (MMUT), plays a central role in funneling propionate to the TCA cycle intermediate, succinate. Our understanding of the fate of propionate in other cell types, specifically, the involvement of the β-oxidation-like and methylcitrate pathways, is limited. In this study, we have used [14C]-propionate tracing in combination with genetic ablation or inhibition of MMUT, to reveal the differential utilization of the B12-dependent and independent pathways for propionate metabolism in fibroblast versus colon cell lines. We demonstrate that itaconate can be used as a tool to investigate MMUT-dependent propionate metabolism in cultured cell lines. While MMUT gates the entry of propionate carbons into the TCA cycle in fibroblasts, colon-derived cell lines exhibit a quantitatively significant or exclusive reliance on the β-oxidation-like pathway. Lipidomics and metabolomics analyses reveal that propionate elicits pleiotropic changes, including an increase in odd-chain glycerophospholipids, and perturbations in the purine nucleotide cycle and arginine/nitric oxide metabolism. The metabolic rationale and the regulatory mechanisms underlying the differential reliance on propionate utilization pathways at a cellular, and possibly tissue level, warrant further elucidation.

Reactive aldehydes are a class of electrophilic low molecular weight compounds that play an essential role in physiological function and lipid peroxidation. These molecules are implicated in many diseases, especially cardiovascular and neurodegenerative diseases, and are potential endogenous markers of lipid peroxidation. However, there are limited options to accurately quantify multiple reactive aldehydes in brain tissue. This study developed and validated a 3-nitrophenylhydrazine derivatization-based LC-MS/MS method to quantify four reactive aldehydes: malondialdehyde, acrolein, 4-hydroxy-2-hexenal and 4-hydroxy-2-nonenal. Method development involved comparing the sensitivity of detection between widely used derivatization reagents: 2,4-dinitrophenylhydrazine and 3-nitrophenylhydrazine. Our data showed that 3-nitrophenylhydrazine resulted in greater sensitivity. Additional method development included evaluation of hydrolysis sample pretreatment, selection of protein precipitation reagent, and optimization of derivatization conditions. The optimized conditions included no hydrolysis and use of 20 % trichloroacetic acid as the protein precipitation reagent. The optimized derivatization condition was 25 mM 3-nitrophenylhydrazine reacted at 20 °C for 30 min. The chromatographic conditions were optimized to reduce matrix effects, ion suppression, and efficient analysis time (<7-minute analytical run). The four aldehyde species were accurately quantified in brain tissue using stable-labeled internal standards. Application of this assay to a traumatic brain injury mouse model revealed significant accumulation of acrolein, 4-hydroxy-2-hexenal, and 4-hydroxy-2-nonenal at 28 days post injury. Overall, a validated method was developed to rapidly quantify the most prominent reactive aldehydes associated with lipid peroxidation during injury progression following acute brain trauma.

Macroautophagy/autophagy is a complex degradation process with a dual role in cell death that is influenced by the cell types that are involved and the stressors they are exposed to. Ferroptosis is an iron-dependent oxidative form of cell death characterized by unrestricted lipid peroxidation in the context of heterogeneous and plastic mechanisms. Recent studies have shed light on the involvement of specific types of autophagy (e.g. ferritinophagy, lipophagy, and clockophagy) in initiating or executing ferroptotic cell death through the selective degradation of anti-injury proteins or organelles. Conversely, other forms of selective autophagy (e.g. reticulophagy and lysophagy) enhance the cellular defense against ferroptotic damage. Dysregulated autophagy-dependent ferroptosis has implications for a diverse range of pathological conditions. This review aims to present an updated definition of autophagy-dependent ferroptosis, discuss influential substrates and receptors, outline experimental methods, and propose guidelines for interpreting the results.Abbreviation: 3-MA:3-methyladenine; 4HNE: 4-hydroxynonenal; ACD: accidentalcell death; ADF: autophagy-dependentferroptosis; ARE: antioxidant response element; BH2:dihydrobiopterin; BH4: tetrahydrobiopterin; BMDMs: bonemarrow-derived macrophages; CMA: chaperone-mediated autophagy; CQ:chloroquine; DAMPs: danger/damage-associated molecular patterns; EMT,epithelial-mesenchymal transition; EPR: electronparamagnetic resonance; ER, endoplasmic reticulum; FRET: Försterresonance energy transfer; GFP: green fluorescent protein;GSH: glutathione;IF: immunofluorescence; IHC: immunohistochemistry; IOP, intraocularpressure; IRI: ischemia-reperfusion injury; LAA: linoleamide alkyne;MDA: malondialdehyde; PGSK: Phen Green™ SK;RCD: regulatedcell death; PUFAs: polyunsaturated fatty acids; RFP: red fluorescentprotein;ROS: reactive oxygen species; TBA: thiobarbituricacid; TBARS: thiobarbituric acid reactive substances; TEM:transmission electron microscopy.

The rapid increase in lipidomic studies has led to a collaborative effort within the community to establish standards and criteria for producing, documenting, and disseminating data. Creating a dynamic easy-to-use checklist that condenses key information about lipidomic experiments into common terminology will enhance the field's consistency, comparability, and repeatability. Here, we describe the structure and rationale of the established Lipidomics Minimal Reporting Checklist to increase transparency in lipidomics research.

Aged individuals with spinal cord injury (SCI) are prevalent with increased mortality and worse outcomes. SCI can cause secondary brain neuroinflammation and neurodegeneration. However, the mechanisms contributing to SCI-induced brain dysfunction are poorly understood. Cell-to-cell signaling through extracellular vesicles (EVs) has emerged as a critical mediator of neuroinflammation, including at a distance through circulation. We have previously shown that SCI in young adult (YA) male mice leads to robust changes in plasma EV count and microRNAs (miRs) content. Here, our goal was to investigate the impact of old age on EVs and brain after SCI. At 24 h post-injury, there was no difference in particle count or size distribution between YA and aged mice. However, aged animals increased expression of EV marker CD63 with SCI. Using the Fireplex® miRs assay, Proteomics, and mass spectrometry-based Lipidomics, circulating EVs analysis identified distinct profiles of miRs, proteins, and lipid components in old and injury animals. In vitro, plasma EVs from aged SCI mice, at a lower concentration comparable to those of YA SCI mice, induced the secretion of pro-inflammatory cytokines and neuronal apoptosis. Systemic administration of plasma EVs from SCI animals was sufficient to impair general physical function and neurological function in intact animals, which is associated with pro-inflammatory changes in the brain. Furthermore, plasma EVs from young animals had rejuvenating effects on naïve aged mice. Collectively, these studies identify the critical changes in circulating EVs cargoes after SCI and in aged animals and support a potential EV-mediated mechanism for SCI-induced brain changes.