1,720,990 research outputs found
Developmental changes in rat surfactant lipidomics in the context of species variability.
No full textLung surfactant comprises mainly phosphatidylcholine (PC) species together with phosphatidylglycerols and surfactant proteins (SP) SP-A to -D. Changes in the concentrations of its principal components dipalmitoyl-PC, palmitoylmyristoyl-PC, palmitoylpalmitoleoyl-PC relative to developmental, structural and physiological differences are only partially understood. Particularly, their attribution to differences in air-liquid interface curvature, compared with dynamic parameters, such as respiratory rate, are controversial.We postulated that during alveolarization the changes in these principal PC components of surfactant differ from those in other phospholipid parameters, and that across endothermic vertebrates their concentrations are related to lung physiology rather than structure. We therefore investigated in rats from postnatal day (d)1 to d42 the pattern of surfactant phospholipids relative to alveolarization (d4-d14), and we discuss these changes in terms of molecular adaptation to pulmonary structure or physiology. Contrary to mammals with advanced alveolarization and increased respiratory rate (RR) at term, concentrations of dipalmitoyl-PC (49-52%) and palmitoylmyristoyl-PC (7-9%) in lung lavage fluid were identical at d1 and d42. At d7-d14, when in rats RR is increased, palmitoyl-myristoyl-PC transiently increased by 2.5- to 3.9-fold at the expense of dipalmitoyl-PC (-32% to 34%) and palmitoyl-palmitoleoyl-PC (-16%). Other lipidomic changes followed essentially different patterns of increase or decrease. Palmitoyl-myristoyl-PC was increased in large aggregates suggesting that it is an integral component of active surfactant. In the overall context of vertebrates, irrespective of age and lung structure, fractions of palmitoyl-myristoyl-PC, dipalmitoyl-PC and palmitoyl-palmitoleoyl-PC correlate with differences in RR rather than alveolar curvature. In adult mammals, however, only concentrations of palmitoyl-palmitoleoyl-PC correlate with RR
Acyl chain-based molecular selectivity for HL60 cellular phosphatidylinositol and of phosphatidylcholine by phosphatidylinositol transfer protein ?
No full textMammalian phosphatidylinositol transfer protein ? (PITP) is an intracellular lipid transporter with a binding site that can accommodate a single molecule of phosphatidylinositol (PI) or phosphatidylcholine (PC). Phospholipids are a heterogeneous population of molecular species that can be distinguished by their characteristic headgroups as well as their acyl chains at the sn-1 and sn-2 position. In this study, we have defined the acyl chain preference for PITP? when presented with a total population of cellular lipids. Recombinant PITP? loaded with bacterial lipid, phosphatidylglycerol (PG), was incubated with permeabilised HL60 cells, followed by recovery of PITP? by affinity chromatography. Lipids extracted from the PITP? were analysed by tandem electrospray ionisation mass spectrometry (ESI-MS) and showed total exchange of acquired bacterial lipids for HL60 cellular PI and PC. Detailed comparison of the molecular species composition of bound phospholipids with those in whole cells permitted the assessment of selectivity of acyl chain binding. For both phospholipid classes, progressive fractional enrichments in bound species possessing shorter acyl chains were apparent with a preference order: 16:1>16:0>18:1>18:0>20:4. A recapitulation of this specificity order was also seen from a dramatically altered range of molecular species present in HL60 cells enriched with arachidonate over many weeks of culture. We speculate that short-chain, saturate-binding preferences under both conditions may reflect properties in vivo. This is consistent with target cell membranes actively remodelling newly delivered phospholipids after transport rather than relying on the transport of the specific molecular species conventionally found in mammalian membranes
Diclofenac mediated derangement of neuroblastoma cell lipidomic profiles is accompanied by increased phosphatidylcholine biosynthesis.
No full textEffect of exogenous nebulised surfactant treatment on plasma phosphatidylcholine synthesis in mechanically ventilated COVID-19 patients
No full textCOVID-19 is associated with significant morbidity and mortality in the intensive care unit. Exogenous surfactant primarily consists of phosphatidylcholines (PC) and may be effective in improving outcomes. Plasma PC, the major circulating phospholipid is synthesised by two biologically different pathways: Cytidine Diphosphate (CDP)-Choline and Phosphatidylethanolamine N-methyltransferase (PEMT) pathways. Plasma PC synthetic pathways in patients undergoing surfactant treatment have not been well understood. To study the effect of exogenous porcine surfactant replacement on plasma PC composition, synthesis and metabolism, twenty mechanically ventilated COVID-19 patients, randomised at 3:2 fashion were assigned to receive surfactant treatment and no treatment. Both patient groups were infused with 3mg/kg of methyl-D9-choline chloride for 3 hours and bloods were collected at 0, 8, 16, 24, 48 and 72 hours. Stable isotope labelling with methyl-D9-Choline chloride combined with neutral loss and precursor scan modes on ESI-MS/MS were used to assess the composition and molecular specificity of PC synthesis via the PEMT and CDP-choline pathway. The analysis showed plasma PC composition primarily consisting of PC16:0/18:2, PC16:0/18:1, PC16:0/20:4 and PC18:0/18:2 in both surfactant and control patient groups, with no significant differences in plasma PC compositions between both groups. Surfactant treated group showed a decrease in methyl-D6-PC and methyl-D3-PC incorporation, possibly indicating decreased PC synthesis via the PEMT pathway, however this was not significant. The methyl-D9-PC incorporation was similar for both groups, with surfactant treated group showing a slightly earlier methyl-D9-PC incorporation and degradation, indicating a faster flux through the CDP-choline pathway. Stable isotope labelling studies of PC enrichment indicate that, although slight variations in PC synthesis were observed, these changes were not statistically significant. This suggests that exogenous surfactant administration does not markedly affect endogenous PC synthesis in plasma
Exhaled breath particles as a novel tool to study lipid composition of epithelial lining fluid from the distal lung
No full textAbstract Background Surfactant phospholipid (PL) composition plays an important role in lung diseases. We compared the PL composition of non-invasively collected exhaled breath particles (PEx) with bronchoalveolar lavage (BAL) and induced sputum (ISP) at baseline and following endotoxin (LPS) challenges. Methods PEx and BAL were collected from ten healthy nonsmoking participants before and after segmental LPS challenge. Four weeks later, PEx and ISP were sampled in the week before and after a whole lung LPS inhalation challenge. PL composition was analysed using mass spectrometry. Results The overall PL composition of BAL, ISP and PEx was similar, with PC(32:0) and PC(34:1) representing the largest fractions in all three sample types (baseline PC(32:0) geometric mean mol%: 52.1, 56.9, and 51.7, PC(34:1) mol%: 11.7, 11.9 and 11.4, respectively). Despite this similarity, PEx PL composition was more closely related to BAL than to ISP. For most lipids comparable inter-individual differences in BAL, ISP, and PEx were found. PL composition of PEx was repeatable. The most pronounced increase following segmental LPS challenge was detected for SM(d34:1) in BAL (0.24 to 0.52 mol%) and following inhalation LPS challenge in ISP (0.45 to 0.68 mol%). An increase of SM(d34:1) following segmental LPS challenge was also detectable in PEx (0.099 to 0.103 mol%). The inhalation challenge did not change PL composition of PEx. Conclusion Our data supports the peripheral origin of PEx. The lack of PL changes in PEx after inhalation challenge might to be due to the overall weaker response of inhaled LPS which primarily affects the larger airways. Compared with BAL, which always contains lining fluid from both peripheral lung and central airways, PEx analysis might add value as a selective and non-invasive method to investigate peripheral airway PL composition. Trial registration NCT03044327, first posted 07/02/2017
Phosphatidylinositol transfer protein, cytoplasmic 1 (PITPNC1) binds and transfers Phosphatidic Acid
No full textPhosphatidylinositol transfer proteins (PITPs) are versatile proteins required for signal transduction and membrane traffic. The best characterised mammalian PITPs are the Class I PITPs, PITP? (PITPNA) and PITP? (PITPNB) which are single domain proteins with a hydrophobic cavity binding a phosphatidylinositol (PI) or phosphatidylcholine (PC) molecule. In this study we report the lipid binding properties of an uncharacterised soluble PITP, phosphatidylinositol transfer protein, cytoplasmic 1 (PITPNC1) (alternative name, RdgB?) of the Class II family. We show that the lipid binding properties of this protein are distinct to Class I PITPs since, beside PI, RdgB? binds and transfers phosphatidic acid (PA) but hardly PC. RdgB? when purified from E.coli is pre-loaded with PA and phosphatidylglycerol (PG) and when incubated with permeabilised HL60 cells, PG is released and PA and PI is now incorporated into RdgB?. Increasing PA levels following activation of endogenous phospholipase D or after addition of bacterial phospholipase D, binding of PA to RdgB? is increased at the expense of PI binding. We propose that RdgB?, when containing PA, regulates an effector protein or can facilitate lipid transfer between membrane compartments
Rapid phospholipid turnover after surfactant nebulization in severe COVID- 19 infection: a randomized clinical trial
No full textStable isotope analysis of dynamic lipidomics
No full textMetabolic pathway flux is a fundamental element of biological activity, which can be quantified using a variety of mass spectrometric techniques to monitor incorporation of stable isotope-labelled substrates into metabolic products. This article contrasts developments in electrospray ionisation mass spectrometry (ESI-MS) for the measurement of lipid metabolism with more established gas chromatography mass spectrometry and isotope ratio mass spectrometry methodologies. ESI-MS combined with diagnostic tandem MS/MS scans permits the sensitive and specific analysis of stable isotope-labelled substrates into intact lipid molecular species without the requirement for lipid hydrolysis and derivatisation. Such dynamic lipidomic methodologies using non-toxic stable isotopes can be readily applied to quantify lipid metabolic fluxes in clinical and metabolic studies in vivo. However, a significant current limitation is the absence of appropriate software to generate kinetic models of substrate incorporation into multiple products in the time domain. Finally, we discuss the future potential of stable isotope-mass spectrometry imaging to quantify the location as well as the extent of lipid synthesis
The composition of pulmonary surfactant from diving mammals
No full textMaintaining a functional pulmonary surfactant system at depth is critical for diving mammals to ensure that inspiration is possible upon re-emergence. The lipid and protein composition of lavage extracts from three pinniped species (California sea lion, Northern elephant seal and Ringed seal) were compared to several terrestrial species. Lavage samples were purified using a NaBr discontinuous gradient. Concentrations of phospholipid classes and molecular species were measured using electrospray ionisation mass spectrometry, cholesterol was measured using high-performance liquid chromatography, surfactant protein A (SP-A) and SP-B were measured using enzyme-linked immunosorbent assays. There were small differences in phospholipid classes, with a lower level of anionic surfactant phospholipids, PG and PI, between diving and terrestrial mammals. There were no differences in PL saturation or SP-A levels between species. PC16:0/14:0, PC16:0/16:1, PC16:0/16:0, long chain PI species and the total concentrations of alkyl–acyl species of PC and PG as a ratio of diacyl species were increased in diving mammals, whereas concentrations of PC16:0/18:1, PG16:0/16:0 and PG16:0/18:1 were decreased. Cholesterol levels were very variable between species and SP-B was very low in diving mammals. These differences may explain the very poor surface activity of pinniped surfactant that we have previously described [Miller, N.J., Daniels, C.B., Schürch, S., Schoel, W.M., Orgeig, S., 2005. The surface activity of pulmonary surfactant from diving mammals
In Vivo Cellular Phosphatidylcholine Kinetics of CD15+ Leucocytes and CD3+ T-Lymphocytes in Adults with Acute Respiratory Distress Syndrome
No full textMammalian cell membranes composed of a mixture of glycerophospholipids, the relative composition of individual phospholipids and the dynamic flux vary between cells. In addition to their structural role, membrane phospholipids are involved in cellular signalling and immunomodulatory functions. In this study, we investigate the molecular membrane composition and dynamic flux of phosphatidylcholines in CD15+ leucocytes and CD3+ lymphocytes extracted from patients with acute respiratory distress syndrome (ARDS). We identified compositional variations between these cell types, where CD15+ cells had relatively higher quantities of alkyl-acyl PC species and CD3+ cells contained more arachidonoyl-PC species. There was a significant loss of arachidonoyl-PC in CD3+ cells in ARDS patients. Moreover, there were significant changes in PC composition and the methyl-D9 enrichment of individual molecular species in CD15+ cells from ARDS patients. This is the first study to perform an in vivo assessment of membrane composition and dynamic changes in immunological cells from ARDS patients
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