Phase-Separated Lipid-Based Nanoparticles: Selective Behavior at the Nano-Bio Interface

The membrane-protein interface on lipid-based nanoparticles influences their in vivo behavior. Better understanding may evolve current drug delivery methods toward effective targeted nanomedicine. Previously, the cell-selective accumulation of a liposome formulation in vivo is demonstrated, through the recognition of lipid phase-separation by triglyceride lipases. This exemplified how liposome morphology and composition can determine nanoparticle-protein interactions. Here, the lipase-induced compositional and morphological changes of phase-separated liposomes-which bear a lipid droplet in their bilayer- are investigated, and the mechanism upon which lipases recognize and bind to the particles is unravelled. The selective lipolytic degradation of the phase-separated lipid droplet is observed, while nanoparticle integrity remains intact. Next, the Tryptophan-rich loop of the lipase is identified as the region with which the enzymes bind to the particles. This preferential binding is due to lipid packing defects induced on the liposome surface by phase separation. In parallel, the existing knowledge that phase separation leads to in vivo selectivity, is utilized to generate phase-separated mRNA-LNPs that target cell-subsets in zebrafish embryos, with subsequent mRNA delivery and protein expression. Together, these findings can expand the current knowledge on selective nanoparticle-protein communications and in vivo behavior, aspects that will assist to gain control of lipid-based nanoparticles.

Radiotherapy skin marking with lancets versus electric marking pen - Comfort, satisfaction, effectiveness and cosmesis results from the randomized, double-blind COMFORTATTOO trial

INTRODUCTION

Set-up skin markings are performed, in several centers, for radiotherapy (RT) treatments. This study aimed to compare two permanent methods: lancets and an electric marking pen, the Comfort Marker 2.0® (CM).

METHODS

This was a prospective, unicentric, randomized study. Patients aged 18 years or older referred to our department to receive RT were recruited. Patients were randomly assigned, in a 1:1 ratio, to receive set-up markings using lancets or CM. The markings arrangement followed our departmental protocols. The coprimary endpoints were patients' comfort and effectiveness. Secondary endpoints included radiation therapists (RTTs) satisfaction and cosmesis.

RESULTS

Between October 2021 and January 2022, 100 patients were enrolled (50 received lancets and 50 CM) and assessed for the comfort and satisfaction outcomes. CM was significantly less painful than the lancets, with 44% and 16% of the patients, respectively, considering the tattooing process painless (RR = 2.75; 95% IC: 1.36 - 5.58). On the RTT-reported satisfaction, CM had significantly easier processes than lancets (98.0% vs. 78.0%, respectively; RR = 1.26; 95% CI: 1.08 - 1.46). For effectiveness and cosmesis assessment, 98 patients were analyzed (48 received lancets and 50 CM). Patients receiving CM had a significantly higher proportion of markings graded as good and excellent compared to those receiving lancets (98.0% and 50.0%, respectively, had ≥75% of the tattoos assessed as good/excellent, RR = 1.96; 95% CI: 1.47 - 2.61). On the cosmetic evaluation, patients receiving CM had significantly better cosmetic markings, with a median score of 4.4 (vs. 3.5 for lancets, p <0.001).

CONCLUSION

The trial results demonstrated that tattooing with the CM is significantly less painful, more effective, easier to apply, and cosmetically superior to tattooing with lancets.

IMPLICATIONS FOR PRACTICE

Tattooing with CM allows for better results regarding pain, quality, ease and cosmesis.

Real‐Time NMR Recording of Fermentation and Lipid Metabolism Processes in Live Microalgae Cells

Non‐invasive and real‐time recording of processes in living cells has been limited to detection of small cellular components such as soluble proteins and metabolites. Here we report a multiphase NMR approach using magic‐angle spinning NMR to synchronously follow microbial processes of fermentation, lipid metabolism and structural dynamic changes in live microalgae cells. Chlamydomonas reinhardtii green algae were highly concentrated, introducing dark fermentation and anoxia conditions. Single‐pulse NMR experiments were applied to obtain temperature‐dependent kinetic profiles of the formed fermentation products. Through dynamics‐based spectral editing NMR, simultaneous conversion of galactolipids into TAG and free fatty acids was observed and rapid loss of rigid lipid structures. This suggests that lipolysis under dark and anoxia conditions finally results in the breakdown of cell and organelle membranes, which could be beneficial for recovery of intracellular microbial useful products.

Glycosphingolipids and Infection. Potential New Therapeutic Avenues

Glycosphingolipids (GSLs), the main topic of this review, are a subclass of sphingolipids. With their glycans exposed to the extracellular space, glycosphingolipids are ubiquitous components of the plasma membrane of cells. GSLs are implicated in a variety of biological processes including specific infections. Several pathogens use GSLs at the surface of host cells as binding receptors. In addition, lipid-rafts in the plasma membrane of host cells may act as platform for signaling the presence of pathogens. Relatively common in man are inherited deficiencies in lysosomal glycosidases involved in the turnover of GSLs. The associated storage disorders (glycosphingolipidoses) show lysosomal accumulation of substrate(s) of the deficient enzyme. In recent years compounds have been identified that allow modulation of GSLs levels in cells. Some of these agents are well tolerated and already used to treat lysosomal glycosphingolipidoses. This review summarizes present knowledge on the role of GSLs in infection and subsequent immune response. It concludes with the thought to apply glycosphingolipid-lowering agents to prevent and/or combat infections.

α-d-Gal-cyclophellitol cyclosulfamidate is a Michaelis complex analog that stabilizes therapeutic lysosomal α-galactosidase A in Fabry disease

α-d-Gal-cyclophellitol cyclosulfamidate is a new class of neutral, conformationally-constrained competitive glycosidase inhibitor that stabilizes α-gal A and prevents its degradation both in vitro and in cellulo by mimicry of the Michaelis complex conformation.

Quantification of globotriaosylsphingosine in plasma and urine of fabry patients by stable isotope ultraperformance liquid chromatography-tandem mass spectrometry

BACKGROUND

Biochemical markers that accurately reflect the severity and progression of disease in patients with Fabry disease and their response to treatment are urgently needed. Globotriaosylsphingosine, also called lysoglobotriaosylceramide (lysoGb3), is a promising candidate biomarker.

METHODS

We synthesized lysoGb3 and isotope-labeled [5,6,7,8,9] (13)C5-lysoGb3 (internal standard). After addition of the internal standard to 25 μL plasma or 400 μL urine from patients with Fabry disease and healthy controls, samples were extracted with organic solvents and the lysoGb3 concentration was quantified by UPLC-ESI-MS/MS (ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry). Calibration curves were constructed with control plasma and urine supplemented with lysoGb3. In addition to lysoGb3, lyso-ene-Gb3 was quantified. Quantification was achieved by multiple reaction monitoring of the transitions m/z 786.4 > 282.3 [M+H](+) for lysoGb3, m/z 791.4 > 287.3 [M+H](+) for [5,6,7,8,9] (13)C5-lysoGb3, and 784.4 > 280.3 [M+H](+) for lyso-ene-Gb3.

RESULTS

The mean (SD) plasma lysoGb3 concentration from 10 classically affected Fabry hemizygotes was 94.4 (25.8) pmol/mL (range 52.7-136.8 pmol/mL), from 10 classically affected Fabry heterozygotes 9.6 (5.8) pmol/mL (range 4.1-23.5 pmol/mL), and from 20 healthy controls 0.4 (0.1) pmol/mL (range 0.3-0.5 pmol/mL). Lyso-ene-Gb3 concentrations were 10%-25% of total lysoGb3. The urine concentration of lysoGb3 was 40-480 times lower than in corresponding plasma samples. Lyso-ene-Gb3 concentrations in urine were comparable or even higher than the corresponding lysoGb3 concentrations.

CONCLUSIONS

This assay for the quantification of lysoGb3 and lyso-ene-Gb3 in human plasma and urine samples will be an important tool in the diagnosis of Fabry disease and for monitoring the effect of enzyme replacement therapy in patients with Fabry disease.

Biomarkers in the diagnosis of lysosomal storage disorders: proteins, lipids, and inhibodies

A biomarker is an analyte indicating the presence of a biological process linked to the clinical manifestations and outcome of a particular disease. In the case of lysosomal storage disorders (LSDs), primary and secondary accumulating metabolites or proteins specifically secreted by storage cells are good candidates for biomarkers. Clinical applications of biomarkers are found in improved diagnosis, monitoring disease progression, and assessing therapeutic correction. These are illustrated by reviewing the discovery and use of biomarkers for Gaucher disease and Fabry disease. In addition, recently developed chemical tools allowing specific visualization of enzymatically active lysosomal glucocerebrosidase are described. Such probes, coined inhibodies, offer entirely new possibilities for more sophisticated molecular diagnosis, enzyme replacement therapy monitoring, and fundamental research.

Paradoxical increase in TAG and DAG content parallel the insulin sensitizing effect of unilateral DGAT1 overexpression in rat skeletal muscle

BACKGROUND

The involvement of muscle triacylglycerol (TAG) storage in the onset of insulin resistance is questioned and the attention has shifted towards inhibition of insulin signalling by the lipid intermediate diacylglycerol (DAG). The enzyme 1,2-acylCoA:diacylglyceroltransferase-1 (DGAT1) esterifies a fatty acyl-CoA on DAG to form TAG. Therefore, the aim of the present study was to investigate if unilateral overexpression of DGAT1 in adult rat Tibialis anterior (TA) muscle will increase conversion of the lipid intermediate DAG into TAG, thereby improving muscle insulin sensitivity.

METHODOLOGY/PRINCIPAL FINDINGS

The DGAT1 gene construct was injected in the left TA muscle of male rats on chow or high-fat (45% kcal) diet for three weeks, followed by application of one 800 V/cm and four 80 V/cm pulses, using the contralateral leg as sham-electroporated control. Seven days after electroporation, muscle specific insulin sensitivity was assessed with a hyperinsulinemic euglycemic clamp using 2-deoxy-[3H]glucose. Here, we provide evidence that unilateral overexpression of DGAT1 in TA muscle of male rats is associated with an increased rather than decreased DAG content. Strikingly, this increase in DAG content was accompanied by improved muscle insulin sensitivity. Interestingly, markers of muscle lipolysis and mitochondrial function were also increased in DGAT1 overexpressing muscle.

CONCLUSIONS/SIGNIFICANCE

We conclude that unilateral DGAT1 overexpression can rescue insulin sensitivity, possibly by increasing DAG and TAG turnover in skeletal muscle. In case of a proper balance between the supply and oxidation of fatty acids in skeletal muscle, the lipid intermediate DAG may not exert harmful effects on insulin signalling.

Neurophysiological, behavioral and morphological abnormalities in the Fabry knockout mice

Fabry disease (OMIM 301500) is a rare X-linked recessive disorder caused by mutations in the alpha-galactosidase gene (GLA). Loss of alpha-galactosidase (alpha-Gal) activity leads to the abnormal accumulation of glycosphingolipids in lysosomes predominantly of vascular endothelial cells. Clinically the disorder presents with angiokeratomas, clouding of the cornea, and renal, cardiac, and cerebrovascular complications. In addition, there is an increased incidence of neuropathic pain in Fabry patients. In this study, we investigated the implications of loss of alpha-galactosidase A activity on sensorimotor function and peripheral nervous system. Similar to the described in Fabry disease patients, the sensorimotor assessment of Fabry mice revealed diminished locomotor activity and warm hypoalgesia as assessed in the hot-plate. Moreover Fabry mice displayed alterations both in balance and co-ordination. By histological analysis, the cyto-architecture of Fabry mice sciatic nerves showed an increase in mean cross-sectional area accompanied by a decrease in the density of non-myelinated fibers as well as a trend for a decreased number of small myelinated fibers, a well established feature of Fabry disease. A relative preservation of large myelinated fibers and nerve conduction velocity measurements was observed. Our findings demonstrate for the first time that Fabry knockout mice have Gb3 accumulation in the peripheral nervous system, alterations in sensorimotor function, hypoalgesia and no impairment of motor nerve conduction.