Neutrophil activation markers can predict rheumatoid arthritis treatment response to the Janus Kinase 1/2 inhibitor baricitinib.

OBJECTIVES: Neutrophils play an important role in regulating immune and inflammatory responses in rheumatoid arthritis (RA). We assessed whether baricitinib, a JAK1/JAK2 inhibitor, could reduce neutrophil activation, and whether a neutrophil activation score could predict treatment response. METHODS: Markers of neutrophil activation, calprotectin, and neutrophil extracellular traps (NETs) were analyzed using ELISA in RA plasma (n=271) and healthy controls (n=39). For RA patients, neutrophil activation markers were measured at baseline, 12 weeks, and 24 weeks after treatment with placebo, 2 mg, and 4 mg baricitinib. Whole blood RNA analyses from multiple randomized baricitinib RA trials were performed to study neutrophil-related transcripts (n=1651). RESULTS: Baseline levels of plasma neutrophil markers were elevated in RA patients compared to healthy controls (p<0.001). Baricitinib reduced levels of soluble calprotectin at 12 and 24 weeks, especially in RA patients responding to treatment, as determined by ACR20. Whole blood RNA analysis revealed similar changes in the predominant neutrophil markers calprotectin and FcαRI upon treatment with baricitinib in three randomized clinical trials involving RA patients at various stages of disease modifying therapy. Clustering analysis of plasma activation markers showed elevated levels of calprotectin and NETs, e.g., a neutrophil activation score, at baseline, could predict treatment response to baricitinib. In contrast, CRP levels could not distinguish between responders and non-responders. CONCLUSIONS: Neutrophil activation markers may add clinical value in predicting treatment response to baricitinib and other drugs targeting RA. This study supports personalized medicine, in treating RA patients, not only based on symptoms, but also based on immunophenotyping.

Effect of Preparation Methods on the Interface of LiBH4/SiO2 Nanocomposite Solid Electrolytes.

Nanocomposites of complex metal hydrides and oxides are promising solid state electrolytes. The interaction of the metal hydride with the oxide results in a highly conducting interface layer. Up until now it has been assumed that the interface chemistry is independent of the nanoconfinement method. Using 29Si solid state NMR and LiBH4/SiO2 as a model system, we show that the silica surface chemistry differs for nanocomposites prepared via melt infiltration or ball milling. After melt infiltration, a Si···H···BH3 complex is present on the interface, together with silanol and siloxane groups. However, after ball milling, the silica surface consists of Si- H sites, and silanol and siloxane groups. We propose that this change is related to a redistribution of silanol groups on the silica surface during ball milling, where free silanol groups are converted to mutually hydrogen-bonded silanol groups. The results presented here help to explain the difference in ionic conductivity between nanocomposites prepared via ball milling and melt infiltration.

Is There Such a Thing as Theological Medicine?

The idea that science must be understood in existential contradiction to religion and even theology is more of a conviction than a philosophical or experiential necessity. Indeed, we may now propose "Theological Medicine" as a new terminology for a perennial reality: that most physicians, health care providers, patients, and their caretakers experience the reality of illness within a theological framework, at least for those who have some degree of spiritual or religious belief. Developing a curriculum in Theological Medicine could develop a mechanism to offer appropriate training to healthcare providers. Such a course would have to be created and delivered by experienced physicians and nursing staff, spiritual advisors, clergy representatives such as pastors or priests from different churches or faith communities, bioethicists, psychologists, social workers, psychotherapists, patient support group members, members of institutional review boards, researchers, and even legal advisors, if available. Continuing professional education requirements also create an opportunity to introduce and evaluate competency in theological medicine, an emerging discipline that could add significant value to the lived experience of medical practice which remains based on the uniquely rich relationship between physician and patient.

The extracellular matrix protein fibronectin promotes metanephric kidney development.

Complex interactions of the branching ureteric bud (UB) and surrounding mesenchymal cells during metanephric kidney development determine the final number of nephrons. Impaired nephron endowment predisposes to arterial hypertension and chronic kidney disease. In the kidney, extracellular matrix (ECM) proteins are usually regarded as acellular scaffolds or as the common histological end-point of chronic kidney diseases. Since only little is known about their physiological role in kidney development, we aimed for analyzing the expression and role of fibronectin. In mouse, fibronectin was expressed during all stages of kidney development with significant changes over time. At embryonic day (E) 12.5 and E13.5, fibronectin lined the UB epithelium, which became less pronounced at E16.5 and then switched to a glomerular expression in the postnatal and adult kidneys. Similar results were obtained in human kidneys. Deletion of fibronectin at E13.5 in cultured metanephric mouse kidneys resulted in reduced kidney sizes and impaired glomerulogenesis following reduced cell proliferation and branching of the UB epithelium. Fibronectin colocalized with alpha 8 integrin and fibronectin loss caused a reduction in alpha 8 integrin expression, release of glial-derived neurotrophic factor and expression of Wnt11, both of which are promoters of UB branching. In conclusion, the ECM protein fibronectin acts as a regulator of kidney development and is a determinant of the final nephron number.

Auditing the prescription drug consumer price index in a changing marketplace.

Changes in the dynamics of prescription drug markets have raised issues regarding whether the United States Bureau of Labor Statistics' (BLS') Prescription Drug Consumer Price Index (CPI-Rx) has adequately kept up with the evolving marketplace. The CPI-Rx limits its sampling frame to retail outpatient outlets and excludes prescription pharmaceuticals dispensed in non-retail settings such as hospitals, physician/clinic outpatient facilities, and nursing homes. Thus, the CPI-Rx overlooks the increasingly important specialty pharmaceuticals dispensed in non-retail settings, whose transactions are instead captured in the overall hospital and professional services component of the medical care CPI. Specialty drugs now account for about 55% of all U.S. drug spending, double the share of a decade earlier. To the extent specialty drug price growth differs from that of traditional pharmaceuticals, the CPI-Rx could provide an inaccurate measure of overall drug price inflation. We calculate a chained Laspeyres CPI using data from the Merative™ MarketScan® Databases for the years 2010-2019 and IQVIA-designated specialty drugs and offer evidence showing that by not sampling specialty drugs in non-retail settings, the CPI-Rx has understated overall U.S. prescription drug inflation by just under 75 basis points annually. We discuss implications for health care policy and suggest the BLS examine the feasibility of publishing an overall pharmaceutical price index incorporating both traditional and specialty pharmaceuticals dispensed in retail and non-retail settings.

Proteomic Associations of Adverse Outcomes in Human Heart Failure.

BACKGROUND: Identifying novel molecular drivers of disease progression in heart failure (HF) is a high-priority goal that may provide new therapeutic targets to improve patient outcomes. The authors investigated the relationship between plasma proteins and adverse outcomes in HF and their putative causal role using Mendelian randomization. METHODS AND RESULTS: The authors measured 4776 plasma proteins among 1964 participants with HF with a reduced left ventricular ejection fraction enrolled in PHFS (Penn Heart Failure Study). Assessed were the observational relationship between plasma proteins and (1) all-cause death or (2) death or HF-related hospital admission (DHFA). The authors replicated nominally significant associations in the Washington University HF registry (N=1080). Proteins significantly associated with outcomes were the subject of 2-sample Mendelian randomization and colocalization analyses. After correction for multiple testing, 243 and 126 proteins were found to be significantly associated with death and DHFA, respectively. These included small ubiquitin-like modifier 2 (standardized hazard ratio [sHR], 1.56; P<0.0001), growth differentiation factor-15 (sHR, 1.68; P<0.0001) for death, A disintegrin and metalloproteinase with thrombospondin motifs-like protein (sHR, 1.40; P<0.0001), and pulmonary-associated surfactant protein C (sHR, 1.24; P<0.0001) for DHFA. In pathway analyses, top canonical pathways associated with death and DHFA included fibrotic, inflammatory, and coagulation pathways. Genomic analyses provided evidence of nominally significant associations between levels of 6 genetically predicted proteins with DHFA and 11 genetically predicted proteins with death. CONCLUSIONS: This study implicates multiple novel proteins in HF and provides preliminary evidence of associations between genetically predicted plasma levels of 17 candidate proteins and the risk for adverse outcomes in human HF.

Tunneling Interpenetrative Lithium Ion Conduction Channels in Polymer-in-Ceramic Composite Solid Electrolytes.

Polymer-in-ceramic composite solid electrolytes (PIC-CSEs) provide important advantages over individual organic or inorganic solid electrolytes. In conventional PIC-CSEs, the ion conduction pathway is primarily confined to the ceramics, while the faster routes associated with the ceramic-polymer interface remain blocked. This challenge is associated with two key factors: (i) the difficulty in establishing extensive and uninterrupted ceramic-polymer interfaces due to ceramic aggregation; (ii) the ceramic-polymer interfaces are unresponsive to conducting ions because of their inherent incompatibility. Here, we propose a strategy by introducing polymer-compatible ionic liquids (PCILs) to mediate between ceramics and the polymer matrix. This mediation involves the polar groups of PCILs interacting with Li+ ions on the ceramic surfaces as well as the interactions between the polar components of PCILs and the polymer chains. This strategy addresses the ceramic aggregation issue, resulting in uniform PIC-CSEs. Simultaneously, it activates the ceramic-polymer interfaces by establishing interpenetrating channels that promote the efficient transport of Li+ ions across the ceramic phase, the ceramic-polymer interfaces, and the intervening pathways. Consequently, the obtained PIC-CSEs exhibit high ionic conductivity, exceptional flexibility, and robust mechanical strength. A PIC-CSE comprising poly(vinylidene fluoride) (PVDF) and 60 wt % PCIL-coated Li3Zr2Si2PO12 (LZSP) fillers showcasing an ionic conductivity of 0.83 mS cm-1, a superior Li+ ion transference number of 0.81, and an elongation of ∼300% at 25 °C could be produced on meter-scale. Its lithium metal pouch cells show high energy densities of 424.9 Wh kg-1 (excluding packing films) and puncture safety. This work paves the way for designing PIC-CSEs with commercial viability.

Proteomic Associations of NT-proBNP (N-Terminal Pro-B-Type Natriuretic Peptide) in Heart Failure With Preserved Ejection Fraction.

BACKGROUND: NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels are variably elevated in heart failure with preserved ejection fraction (HFpEF), even in the presence of increased left ventricular filling pressures. NT-proBNP levels are prognostic in HFpEF and have been used as an inclusion criterion for several recent randomized clinical trials. However, the underlying biologic differences between HFpEF participants with high and low NT-proBNP levels remain to be fully understood. METHODS: We measured 4928 proteins using an aptamer-based proteomic assay (SOMAScan) in available plasma samples from 2 cohorts: (1) Participants with HFpEF enrolled in the PHFS (Penn Heart Failure Study; n=253); (2) TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist Trial) participants in the Americas (n=218). We assessed the relationship between SOMAScan-derived plasma NT-proBNP and levels of other proteins available in the SOMAScan assay version 4 using robust linear regression, with correction for multiple comparisons, followed by pathway analysis. RESULTS: NT-proBNP levels exhibited prominent proteome-wide associations in PHFS and TOPCAT cohorts. Proteins most strongly associated with NT-proBNP in both cohorts included SVEP1 (sushi, von Willebrand factor type-A, epidermal growth factor, and pentraxin domain containing 1; ßTOPCAT=0.539; P<0.0001; ßPHFS=0.516; P<0.0001) and ANGPT2 (angiopoietin 2; ßTOPCAT=0.571; P<0.0001; ßPHFS=0.459; P<0.0001). Canonical pathway analysis demonstrated consistent associations with multiple pathways related to fibrosis and inflammation. These included hepatic fibrosis and inhibition of matrix metalloproteases. Analyses using cut points corresponding to estimated quantitative concentrations of 360 pg/mL (and 480 pg/mL in atrial fibrillation) revealed similar proteomic associations. CONCLUSIONS: Circulating NT-proBNP levels exhibit prominent proteomic associations in HFpEF. Our findings suggest that higher NT-proBNP levels in HFpEF are a marker of fibrosis and inflammation. These findings will aid the interpretation of NT-proBNP levels in HFpEF and may guide the selection of participants in future HFpEF clinical trials.

Far-travelled 3700 km lateral magma propagation just below the surface of Venus.

The Great Dyke of Atla Regio (GDAR) is traced for ~3700 km on Venus, as a surface graben (narrow trough) interpreted to overlie a continuous laterally-emplaced underlying mafic dyke (vertical magma-filled crack). The GDAR belongs to a giant radiating dyke swarm associated with Ozza Mons (volcano), Atla Regio plume, and was fed from a magma reservoir ~600 km south of the Ozza Mons centre. A 50-degree counter-clockwise swing of the GDAR at 1200 km from the centre is consistent with a 1200 km radius for the underlying Ozza Mons plume head, and a stress link to the 10,000 km long Parga Chasmata rift system. Our discovery of the GDAR, should spur the search for additional long continuous single dykes on Venus (and Earth), with implications for estimating plume head size, locating buffered magma reservoirs, mapping regional stress variation at a geological instant, and revealing relative ages (through cross-cutting relationships) over regional-scale distances.

Induced Attenuation of Scleral TGF-ß Signaling in Mutant Mice Increases Susceptibility to IOP-Induced Optic Nerve Damage.

Purpose: Axonal optic nerve (ON) damage in glaucoma is characteristically associated with increased amounts of active transforming growth factor-beta 2 (TGF-ß2) in the ON head. Here we investigated the functional role of scleral TGF-ß signaling in glaucoma. Methods: A deficiency of Tgfbr2, which encodes for TGF-ß receptor type II (TGF-ßRII), the essential receptor for canonical TGF-ß signaling, was induced in fibroblasts (including those of the sclera) of mutant mice. To this end, 5-week-old mice were treated with tamoxifen eye drops. Experimental glaucoma was induced in 8-week-old mice using a magnetic microbead (MB) model. After 6 weeks of high intraocular pressure (IOP), the ON axons and their somata in the retina were labeled by paraphenylenediamine (PPD) and RNA-binding protein with multiple splicing (RBPMS) immunohistochemistry, respectively, and quantified. Results: Tamoxifen treatment resulted in a significant decrease of TGF-ßRII and its mRNA in the sclera. After 6 weeks of high IOP, reduced numbers of PPD-stained ON axons were seen in MB-injected eyes in comparison with not-injected contralateral eyes. Moreover, MB injection also led to a decrease of retinal ganglion cell (RGC) somata as seen in RBPMS-stained retinal wholemounts. Axon loss and RGC loss were significantly higher in mice with a fibroblast specific deficiency of TGF-ßRII in comparison with control animals. Conclusions: We conclude that the ablation of scleral TGF-ß signaling increases the susceptibility to IOP-induced ON damage. Scleral TGF-ß signaling in mutant mice appears to be beneficial for ON axon survival in experimentally induced glaucoma.

Retinal Pigmented Epithelium-Derived Ectopic Norrin Does Not Promote Intraretinal Angiogenesis in Transgenic Mice.

Formation of intraretinal capillaries and inner blood-retinal barrier during development requires norrin, a ligand of the canonical wingless/integrated (Wnt)/ß-catenin signaling pathway. Here we addressed the question whether retinal pigmented epithelium (RPE)-derived overexpression of norrin in transgenic mice rescues the vascular phenotype caused by norrin deficiency. To this end, we generated NdpKO/Rpe65-Norrin mice and analyzed the activation of ß-catenin signaling, the development of intraretinal capillaries, and the expression of blood-retinal barrier marker molecules. RPE-derived norrin induced retinal ß-catenin signaling but failed to rescue the vascular developmental defects and the breakdown of the blood-retinal barrier in norrin-deficient mice. Sites of ectopic norrin expression and the amounts of secreted transgenic protein are critical factors to enable the angiogenic properties of norrin.

Histomorphometry of the Sural Nerve for Use as a CFNG in Facial Reanimation Procedures.

Facial palsy (FP) is a debilitating nerve pathology. Cross Face Nerve Grafting (CFNG) describes a surgical technique that uses nerve grafts to reanimate the paralyzed face. The sural nerve has been shown to be a reliable nerve graft with little donor side morbidity. Therefore, we aimed to investigate the microanatomy of the sural nerve. Biopsies were obtained from 15 FP patients who underwent CFNG using sural nerve grafts. Histological cross-sections were fixated, stained with PPD, and digitized. Histomorphometry and a validated software-based axon quantification were conducted. The median age of the operated patients was 37 years (5-62 years). There was a significant difference in axonal capacity decrease towards the periphery when comparing proximal vs. distal biopsies (p = 0.047), while the side of nerve harvest showed no significant differences in nerve caliber (proximal p = 0.253, distal p = 0.506) and axonal capacity for proximal and distal biopsies (proximal p = 0.414, distal p = 0.922). Age did not correlate with axonal capacity (proximal: R = -0.201, p = 0.603; distal: R = 0.317, p = 0.292). These novel insights into the microanatomy of the sural nerve may help refine CFNG techniques and individualize FP patient treatment plans, ultimately improving overall patient outcomes.

Intravenous injection of cyclosporin A loaded lipid nanocapsules fights inflammation and immune system activation in a mouse model of diabetic retinopathy.

Inflammation and immune system activation are key pathologic events in the onset and escalation of diabetic retinopathy (DR). Both are driven by cytokines and complement originating from the retinal pigment epithelium (RPE). Despite the RPE's pivotal role, there is no therapeutic tool to specifically interfere with the RPE-related pathomechanism. A therapy that addresses RPE cells and counteracts inflammation and immune response would be of paramount value for the early treatment of DR, where currently are no specific therapies available. Here, we utilized lipoprotein-mimetic lipid nanocapsules to deliver the anti-inflammatory and immunosuppressive drug cyclosporin A (CsA) to RPE cells. Using a mouse model of DR that mirrors all pathologic aspects of human DR, we demonstrate that intravenously applied CsA-loaded lipid nanocapsules comprehensively counteract inflammation and immune system activation. One single injection suppressed the expression of pro-inflammatory cytokines, dampened macrophage infiltration, and prevented macrophage and microglia activation in eyes with DR. This work shows that CsA-loaded lipid nanocapsules can offer new avenues for the treatment of DR.

IL17A Blockade with Ixekizumab Suppresses MuvB Signaling in Clinical Psoriasis.

Unbiased informatics approaches have the potential to generate insights into uncharacterized signaling pathways in human disease. In this study, we generated longitudinal transcriptomic profiles of plaque psoriasis lesions from patients enrolled in a clinical trial of the anti-IL17A antibody ixekizumab (IXE). This dataset was then computed against a curated matrix of over 700 million data points derived from published psoriasis and signaling node perturbation transcriptomic and chromatin immunoprecipitation-sequencing datasets. We observed substantive enrichment within both psoriasis-induced and IXE-repressed gene sets of transcriptional targets of members of the MuvB complex, a master regulator of the mitotic cell cycle. These gene sets were similarly enriched for pathways involved in the regulation of the G2/M transition of the cell cycle. Moreover, transcriptional targets for MuvB nodes were strongly enriched within IXE-repressed genes whose expression levels correlated strongly with the extent and severity of the psoriatic disease. In models of human keratinocyte proliferation, genes encoding MuvB nodes were transcriptionally repressed by IXE, and depletion of MuvB nodes reduced cell proliferation. Finally, we made the expression and regulatory networks that supported this study available as a freely accessible, cloud-based hypothesis generation platform. Our study positions inhibition of MuvB signaling as an important determinant of the therapeutic impact of IXE in psoriasis.

Re-investigating the structure-property relationship of the solid electrolytes Li 3-x In1-x Zr x Cl6 and the impact of In-Zr(iv) substitution.

Chloride-based solid electrolytes are considered interesting candidates for catholytes in all-solid-state batteries due to their high electrochemical stability, which allows the use of high-voltage cathodes without protective coatings. Aliovalent Zr(iv) substitution is a widely applicable strategy to increase the ionic conductivity of Li3M(iii)Cl6 solid electrolytes. In this study, we investigate how Zr(iv) substitution affects the structure and ion conduction in Li3-x In1-x Zr x Cl6 (0 ≤ x ≤ 0.5). Rietveld refinement using both X-ray and neutron diffraction is used to make a structural model based on two sets of scattering contrasts. AC-impedance measurements and solid-state NMR relaxometry measurements at multiple Larmor frequencies are used to study the Li-ion dynamics. In this manner the diffusion mechanism and its correlation with the structure are explored and compared to previous studies, advancing the understanding of these complex and difficult to characterize materials. It is found that the diffusion in Li3InCl6 is most likely anisotropic considering the crystal structure and two distinct jump processes found by solid-state NMR. Zr-substitution improves ionic conductivity by tuning the charge carrier concentration, accompanied by small changes in the crystal structure which affect ion transport on short timescales, likely reducing the anisotropy.

Aluminium ion doping mechanism of lithium thiophosphate based solid electrolytes revealed with solid-state NMR.

We investigate the impact of Al incorporation on the structure and dynamics of Al-doped lithium thiophosphates (Li3-3xAlxPS4) based on ß-Li3PS4. 27Al and 6Li magic-angle spinning NMR spectra confirm that Al3+ ions occupy octahedral sites in the structure. Quantitative analyses of 27Al NMR spectra show that the maximum Al incorporation is x = 0.06 in Li3-3xAlxPS4. The ionic conductivity of ß-Li3PS4 is enhanced by over a factor 3 due to Al incorporation. Further increase of the Al doping level leads to the formation of a more complicated material consisting of multiple crystalline and distorted phases as indicated by 31P NMR spectra and powder X-ray diffraction. Consequently, novel Li ion diffusion pathways develop leading to a very high ionic conductivity at room temperature. NMR relaxometry shows that the activation barrier for long-range Li ion diffusion in ß-Li3PS4 hardly changes upon Al incorporation, but the onset temperature for motional narrowing comes down significantly due to Al doping. The activation barrier in the subsequently formed multiphase material decreases significantly, however, indicating a different more efficient Li ion conduction pathway.

Self-organized hetero-nanodomains actuating super Li+ conduction in glass ceramics.

Easy-to-manufacture Li2S-P2S5 glass ceramics are the key to large-scale all-solid-state lithium batteries from an industrial point of view, while their commercialization is greatly hampered by the low room temperature Li+ conductivity, especially due to the lack of solutions. Herein, we propose a nanocrystallization strategy to fabricate super Li+-conductive glass ceramics. Through regulating the nucleation energy, the crystallites within glass ceramics can self-organize into hetero-nanodomains during the solid-state reaction. Cryogenic transmission electron microscope and electron holography directly demonstrate the numerous closely spaced grain boundaries with enriched charge carriers, which actuate superior Li+-conduction as confirmed by variable-temperature solid-state nuclear magnetic resonance. Glass ceramics with a record Li+ conductivity of 13.2 mS cm-1 are prepared. The high Li+ conductivity ensures stable operation of a 220 µm thick LiNi0.6Mn0.2Co0.2O2 composite cathode (8 mAh cm-2), with which the all-solid-state lithium battery reaches a high energy density of 420 Wh kg-1 by cell mass and 834 Wh L-1 by cell volume at room temperature. These findings bring about powerful new degrees of freedom for engineering super ionic conductors.

Dietary nitrate biochemistry and physiology. An update on clinical benefits and mechanisms of action.

It is now more than 35 years since endothelium derived relaxing factor was identified as nitric oxide (NO). The last few decades have seen an explosion around nitric oxide biochemistry, physiology and clinical translation. The science reveals that all chronic disease is associated with decreased blood flow to the affected organ which results in increased inflammation, oxidative stress and immune dysfunction. This is true for cardiovascular disease, neurological disease, kidney, lung, liver disorders and every other major disorder. Since nitric oxide controls and regulates blood flow, oxygen and nutrient delivery to every cell, tissue and organ in the body and also mitigates inflammation, oxidative stress and immune dysfunction, a focus on restoring nitric oxide production is an obvious therapeutic strategy for a number of poorly managed chronic diseases. Since dietary nitrate is a major contributor to endogenous nitric oxide production, it should be considered as a means of therapy and restoration of nitric oxide. This review will update on the current state of the science and effects of inorganic nitrate administered through the diet on several chronic conditions and reveal how much is needed. It is clear now that antiseptic mouthwash and use of antacids disrupt nitrate metabolism to nitric oxide leading to clinical symptoms of nitric oxide deficiency. Based on the science, nitrate should be considered an indispensable nutrient that should be accounted for in dietary guidelines.

Alterations in ether lipid metabolism and the consequences for the mouse lipidome.

Alkylglycerol monooxygenase (AGMO) and plasmanylethanolamine desaturase (PEDS1) are enzymes involved in ether lipid metabolism. While AGMO degrades plasmanyl lipids by oxidative cleavage of the ether bond, PEDS1 exclusively synthesizes a specific subclass of ether lipids, the plasmalogens, by introducing a vinyl ether double bond into plasmanylethanolamine phospholipids. Ether lipids are characterized by an ether linkage at the sn-1 position of the glycerol backbone and they are found in membranes of different cell types. Decreased plasmalogen levels have been associated with neurological diseases like Alzheimer's disease. Agmo-deficient mice do not present an obvious phenotype under unchallenged conditions. In contrast, Peds1 knockout mice display a growth phenotype. To investigate the molecular consequences of Agmo and Peds1 deficiency on the mouse lipidome, five tissues from each mouse model were isolated and subjected to high resolution mass spectrometry allowing the characterization of up to 2013 lipid species from 42 lipid subclasses. Agmo knockout mice moderately accumulated plasmanyl and plasmenyl lipid species. Peds1-deficient mice manifested striking changes characterized by a strong reduction of plasmenyl lipids and a concomitant massive accumulation of plasmanyl lipids resulting in increased total ether lipid levels in the analyzed tissues except for the class of phosphatidylethanolamines where total levels remained remarkably constant also in Peds1 knockout mice. The rate-limiting enzyme in ether lipid metabolism, FAR1, was not upregulated in Peds1-deficient mice, indicating that the selective loss of plasmalogens is not sufficient to activate the feedback mechanism observed in total ether lipid deficiency.

Normal plasmalogen levels are maintained in tissues from mice with hepatocyte-specific deletion in peroxin 5.

On the basis of findings that cultured rat hepatocytes secrete lipoprotein with a high plasmalogen content and the occurrence of this lipid in human serum, it has been suggested that hepatocytes play a role in the supply of plasmalogens to tissues. We tested this hypothesis in a mouse with a hepatocyte-specific defect in peroxisomes, an organelle essentially required for plasmalogen biosynthesis. We analyzed plasmalogens in lipid extracts of forebrain, liver and five further tissues and in plasma by reaction with dansylhydrazine in hydrochloric acid, which cleaves the vinyl ether of plasmalogens and forms a fluorescent dansylhydrazone, which we quantified by reversed phase high performance liquid chromatography. Reaction with dansylhydrazine in acetic acid was used to quantify free aldehydes as a control. Our results show normal levels of plasmalogens in plasma and in all tissues examined, including forebrain and the liver, irrespective of the inactivation of hepatic peroxisomes. None of the selected ether lipids analyzed by mass spectrometry in plasma and liver was decreased in the mice deficient in liver peroxisomes. In contrast, we found three plasmenylcholine species which were even significantly increased in the livers of these animals. Quantification of mRNA expression of plasmalogen biosynthetic enzymes revealed particularly low expression of fatty acyl-CoA reductase, the key regulatory enzyme of plasmalogen biosynthesis, in liver, with and without hepatic peroxisome deficiency. Our results do not support the suggested role of hepatocytes in supplying plasmalogens to tissues.