Biology subjects

Feelisch, M.

Publications and source records attributed to Feelisch, M..

6 recordsLinked to original sources

bioRxiv2025

Liposomal encapsulation of L-arginine and L-citrulline enhances therapeutic effects in a rat model of Preeclampsia and Fetal Growth Restriction

BackgroundL-arginine and L-citrulline improve vascular health in Preeclampsia (PE) and Fetal growth restriction (FGR). However, the short half-life of these amino acids limits their efficacy. This study investigates pharmacokinetics, delivery, and therapeutic outcomes of liposomal encapsulation of L-arginine and L-citrulline in a rat model of PE and FGR. MethodFirstly, the pharmacokinetics of liposome-encapsulated L-arginine (Encapsulated L-arg) was compared to that of free L-arginine (Free L-arg) in normal pregnant (NP) dams, following single intravenous administration. Secondly, the therapeutic effect on maternal blood pressure and fetal weight were studied in NP rats and the reduced uterine perfusion pressure (RUPP) model for PE and FGR. Treatment groups consisted of Encapsulated L-arginine and L-citrulline (Encapsulated AAs); ratio 1:1, Free L-arginine and L-citrulline (AAs), or PBS, administered intravenously for five consecutive days. Blood and organs were analyzed for amino acid concentrations and fluorescence to assess the biodistribution profile of the liposomes. Nitrite and nitrate were quantified to measure changes in endogenous nitric oxide production in the pharmacokinetic study. ResultsLiposomal encapsulation increased the area under the curve of blood arginine concentration-time curves >120-fold. Encapsulated AAs led to a marked increase in plasma and placental tissue concentrations compared to their free forms. Encapsulated AAs reduced maternal blood pressure in RUPP without affecting fetal weight. Enlarged spleens were observed in both Encapsulated AAs groups. ConclusionsThe enhanced pharmacokinetics enabled by liposomal encapsulation effectively increased placental delivery of L-arginine and L-citrulline and reduced hypertension. Optimizing composition could enhance efficacy on FGR, making Encapsulated AAs a promising strategy for managing PE and FGR. The etiology of the observed maternal splenomegaly observed warrants further research before this novel approach can be clinically implemented.

pharmacology and toxicology↗

bioRxiv2024

Chronic inorganic nitrate supplementation does not improve metabolic health and worsens disease progression in mice with diet-induced obesity.

Inorganic nitrate (NO3-) has been proposed to be of therapeutic use as a dietary supplement in obesity and related conditions including the Metabolic Syndrome (MetS), type-II diabetes and metabolic dysfunction associated steatotic liver disease (MASLD). Administration of NO3- to endothelial nitric oxide synthase-deficient mice reversed aspects of MetS, however the impact of NO3- supplementation in diet-induced obesity is not well understood. Here we investigated the whole-body metabolic phenotype and cardiac and hepatic metabolism in mice fed a high-fat high-sucrose (HFHS) diet for up to 12-months of age, supplemented with 1 mM NaNO3 (or NaCl) in their drinking water. HFHS-feeding was associated with a progressive obesogenic and diabetogenic phenotype, which was not ameliorated by NO3-. Furthermore, HFHS-fed mice supplemented with NO3- showed elevated levels of cardiac fibrosis, and accelerated progression of MASLD including development of hepatocellular carcinoma in comparison with NaCl-supplemented mice. NO3- did not enhance mitochondrial {beta}-oxidation capacity in any tissue assayed and did not suppress hepatic lipid accumulation, suggesting it does not prevent lipotoxicity. We conclude that NO3- is ineffective in preventing the metabolic consequences of an obesogenic diet and may instead be detrimental to metabolic health against the background of HFHS-feeding. This is the first report of an unfavorable effect of long-term nitrate supplementation in the context of the metabolic challenges of overfeeding, warranting urgent further investigation into the mechanism of this interaction. New & NoteworthyInorganic nitrate has been suggested to be of therapeutic benefit in obesity-related conditions as it increases nitric oxide bioavailability, enhances mitochondrial {beta}-oxidation and reverses Metabolic Syndrome in eNOS-/- mice. However, we here show that over 12 months, nitrate was ineffective in preventing metabolic consequences in high-fat high-sucrose fed mice, and worsened aspects of metabolic health, impairing cholesterol handling, increasing cardiac fibrosis, and exacerbating steatotic liver disease progression, with acceleration to hepatocellular carcinoma.

physiology↗

bioRxiv2023

Methods for the analysis of skin microbiomes: a comparison of sampling processes and 16S rRNA hypervariable regions.

BackgroundThe skin microbiome is increasingly recognised as a critical component of the innate skin immune response and is central to the pathogenesis of many inflammatory skin disorders including atopic dermatitis. Previous studies have not looked in detail at the impact of changing both sampling methodology and hypervariable region sequencing for skin microbiome analysis. ObjectivesWe set out to undertake a detailed analysis comparing microbe population diversity and resolution at the single species level by swab, tape, scrape and scrape then swab sampling assayed by hypervariable region sequencing. MethodsIn triplicate samples from the antecubital fossa were taken from healthy volunteers for 16s RNA analysis by primer amplification for hypervariable regions 1-3, and 3-4. ResultsAlpha (phylogenetic) diversity was the greatest with tape sampling and V1-3 analysis, whereas for V4, tape and swab were equivalent. Scrape sampling showed lower alpha diversity at both V1-3 and V4. All measures of beta diversity showed the scrape methodology yielded a lesser diversity than the others. Phyla composition was similar across all sampling methodologies. Minor differences in composition were noted between V1-3 and V4 sequencing, but V1-3 was optimal for identification of firmicutes (including staphylococci). ConclusionsIn the methodological planning of skin microbiome analysis skin scientists need to consider the microbes of interest to choose the optimal hypervariable region to sequence, and harmonisation of methodological approaches would be beneficial to the field. For detection of staphylococci on flexural skin, we would recommend tape sampling with analysis of V1-3. Whats already known about this topic?O_LIPrevious microbiome studies have utilised many different methodologies, but a detailed comparison of their utility in skin research has not been undertaken C_LIO_LIMethodological choices in skin microbiome analysis affect both sensitivity to detect diversity and sensitivity to identify at a species level C_LIO_LIOptimisation to detect diversity and species identification can require different approaches C_LI What does this study add?O_LIOur study compared a matrix the four most widely utilised skin sampling methodologies and the two principle means for hypervariable gene analysis. C_LIO_LIWe show that alpha diversity is optimal with tape sampling C_LIO_LIAdditionally, in contrast to gut microbiome analyses, in the skin hypervariable region V1-3 analysis is superior to V4 when the species of interest are staphylococci. C_LI

microbiology↗

bioRxiv2022

mRNA therapy restores ureagenesis and corrects glutathione metabolism in argininosuccinic aciduria

Argininosuccinate lyase (ASL) is a key enzyme integral to the hepatic urea cycle which is required for ammonia detoxification, and the citrulline-nitric oxide (NO) cycle for NO production. ASL deficient patients present with argininosuccinic aciduria (ASA), an inherited metabolic disease with hyperammonaemia and a chronic systemic phenotype with neurocognitive impairment and chronic liver disease. ASL deficiency as an inherited model of systemic NO deficiency, shows enhanced nitrosative and oxidative stress. Here, we describe the dysregulation of glutathione biosynthesis and upstream cysteine utilization in ASL-deficient patients and mice using targeted metabolomics and in vivo positron emission tomography (PET) imaging using (S)-4-(3-18F-fluoropropyl)-L-glutamate ([18F]FSPG). Upregulation of cysteine metabolism contrasted with glutathione depletion and down-regulated antioxidant pathways. hASL mRNA encapsulated in lipid nanoparticles corrected and rescued the neonatal and adult Asl-deficient mouse phenotypes, respectively, enhancing ureagenesis and glutathione metabolism and ameliorating chronic liver disease. We further present [18F]FSPG PET as a novel non-invasive diagnostic tool to assess liver disease and therapeutic efficacy in ASA. These findings support clinical translation of mRNA therapy for ASA.

genetics↗

bioRxiv2021

Metabolic dysfunction induced by high-fat diet modulates hematopoietic stem and myeloid progenitor cells in brown adipose tissue of mice

Brown adipose tissue (BAT) may be an important metabolic regulator of whole-body glucose. While important roles have been ascribed to macrophages in regulating metabolic functions in BAT, little known is known of the roles of other immune cells subsets, particularly dendritic cells (DCs). Eating a high fat diet may compromise the development of hematopoietic stem and progenitor cells (HSPC) - which give rise to DCs - in bone marrow, with less known of its effects in BAT. We have previously demonstrated that ongoing exposure to low-dose ultraviolet radiation (UVR) significantly reduced the whitening effect of eating a high-fat diet upon interscapular (i)BAT of mice. Here, we examined whether this observation may be linked to changes in the phenotype of HSPC and myeloid-derived immune cells in iBAT and bone marrow of mice using 12-colour flow cytometry. Many HSPC subsets declined in both iBAT and bone marrow with increasing metabolic dysfunction. Conversely, with rising adiposity and metabolic dysfunction, conventional (c)DCs increased in both of these tissues. When compared to low-fat diet, consumption of high-fat diet significantly reduced proportions of myeloid, common myeloid and megakaryocyte-erythrocyte progenitors in iBAT, and short-term hematopoietic stem cells in bone marrow. In mice fed a high-fat diet, exposure to low-dose UVR significantly reduced proportions of cDCs in iBAT, independently of nitric oxide release from irradiated skin (blocked using the scavenger, cPTIO), but did not significantly modify HSPC subsets in either tissue. Further studies are needed to determine whether changes in these cell populations contribute towards metabolic dysfunction.

cell biology↗

bioRxiv2018

Protein nitration is a physiological regulator of cardiac lactate dehydrogenase active site loop mobility and activity

Protein tyrosine nitration is a hallmark of oxidative stress related disease states, commonly detected as anti-nitrotyrosine immunoreactivity. The precise reactive oxygen sources, mechanisms of nitration as well as the modified target proteins and functional consequences, however, remain often unclear. Here we explore protein tyrosine nitration under basal conditions and find surprisingly physiologically nitrated proteins. Upon purifying a prominent physiologically nitrotyrosine immunopositive in hearts from mouse, rat and pig, we identify it as lactate dehydrogenase (LDH). Mechanistically, LDHs degree of basal nitration depended on two canonical sources, NO synthase (NOS) and myeloperoxidase (MPO), respectively. When validating the nitrated amino acid by MALDI-TOF mass spectrometry, we, surprisingly, located LDH nitration not to a tyrosine but the C-terminal tryptophan, Trp324. Molecular dynamics simulations suggested that Trp324 nitration restricts the interaction of the active site loop with the C-terminal -helix essential for activity. This prediction was confirmed by enzyme kinetics revealing an apparent lower Vmax of nitrated LDH, although yet unidentified concurrent oxidative modifications may contribute. Protein nitration is, thus, not a by definition disease marker but reflects also physiological signaling by eNOS/NO, MPO/nitrite and possibly other pathways. The commonly used assay of anti-nitrotyrosine immunoreactivity is apparently cross-reactive to nitrotryptophan requiring a reevaluation of the protein nitration literature. In the case of LDH, nitration of Trp324 is aggravated under cardiac metabolic stress conditions and functionally limits maximal enzyme activity. Trp324-nitrated LDH may serve both as a previously not recognized disease biomarker and possibly mechanistic lead to understand the metabolic changes under these conditions.

biochemistry↗