Efficient delivery of short interfering RNAs reflects a prerequisite for the development of RNA interference therapeutics. Here, we describe highly specific nanoparticles, based on near infrared fluorescent polymethine dye-derived targeting moieties coupled to biodegradable polymers. The fluorescent dye, even when coupled to a nanoparticle, mimics a ligand for hepatic parenchymal uptake transporters resulting in hepatobiliary clearance of approximately 95% of the dye within 45 min. Body distribution, hepatocyte uptake and excretion into bile of the dye itself, or dye-coupled nanoparticles can be tracked by intravital microscopy or even non-invasively by multispectral optoacoustic tomography. Efficacy of delivery is demonstrated in vivo using 3-hydroxy-3-methyl-glutaryl-CoA reductase siRNA as an active payload resulting in a reduction of plasma cholesterol levels if siRNA was formulated into dye-functionalised nanoparticles. This suggests that organ-selective uptake of a near infrared dye can be efficiently transferred to theranostic nanoparticles allowing novel possibilities for personalised silencing of disease-associated genes.

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Sepsis induces reprogramming of the hepatic transcriptome. This includes induction of adaptive acute-phase proteins but also repression of phase I, II metabolism and transport with important implications for monitoring and pharmacotherapy.

Rationale: The biological functions of cholesterol are diverse, ranging from cell membrane integrity and signalling, immunity, to the synthesis of steroid and sex hormones, Vitamin D, bile acids and oxysterols. Multiple studies have demonstrated hypocholesterolemia in sepsis, the degree of which is an excellent prognosticator of poor outcomes. However, the clinical significance of hypocholesterolemia has been largely unrecognized.Objectives/Methods: We undertook a detailed review of the biological roles of cholesterol, the impact of sepsis, its reliability as a prognosticator in sepsis, and the potential utility of cholesterol as a treatment.Measurements and Main Results: Sepsis affects cholesterol synthesis, transport and metabolism. This likely impacts upon its biological functions including immunity, hormone and vitamin production, and cell membrane receptor sensitivity. Early preclinical studies show promise for cholesterol as a pleiotropic therapeutic agent.Conclusions: Hypocholesterolemia is a frequent condition in sepsis and an important early prognosticator. Low plasma levels are associated with wider changes in cholesterol metabolism and its functional roles, and these appear to play a significant role in sepsis pathophysiology. The therapeutic impact of cholesterol elevation warrants further investigation.

Dye-loaded micelles of 10 nm diameter formed from amphiphilic graft copolymers composed of a hydrophobic poly­(methyl methacrylate) backbone and hydrophilic poly­(2-ethyl-2-oxazoline) side chains with a degree of polymerization of 15 were investigated concerning their cellular interaction and uptake in vitro as well as their interaction with local and circulating cells of the reticuloendothelial system in the liver by intravital microscopy. Despite the high molar mass of the individual macromolecules (M n ≈ 20 kg mol–1), backbone end group modification by attachment of a hydrophilic anionic fluorescent probe strongly affected the in vivo performance. To understand these effects, the end group was additionally modified by the attachment of four methacrylic acid repeating units. Although various micelles appeared similar in dynamic light scattering and cryo-transmission electron microscopy, changes in the micelles were evident from principal component analysis of the Raman spectra. Whereas an efficient stealth effect was found for micelles formed from polymers with anionically charged or thiol end groups, a hydrophobic end group altered the micelles’ structure sufficiently to adapt cell-type specificity and stealth properties in the liver.

Strategies to deliver drugs using nanocarriers, which are passively or actively targeted to their alleged site of action might favorably affect benefit-risk profiles of novel therapeutics. Here we tested the hypothesis whether the physico-chemical properties of the cargo as well as the actual conditions during encapsulation interfere during formulation of nanoparticular cargo-carrier systems. On the basis of previous work, a versatile class of nanocarriers is polyether-based ABC triblock terpolymer micelles with diameters below 50 nm. Their tunable chemistry and size allows to systematically vary important parameters. We demonstrate in vivo differences in pharmacokinetics and biodistribution not only dependent on micellar net charge but also on the properties of encapsulated (model) drugs and their localization within the micelles. On the basis of in vitro and in vivo evidence we propose that depending on drug cargo and encapsulation conditions micelles with homogeneous or heterogeneous corona structure are formed, contributing to an altered pharmacokinetic profile as differences in cargo location occur. Thus, these interactions have to be considered when a carrier system is selected to achieve optimal delivery to a given tissue.

Liver failure is a life-threatening complication of infections restricting the host's response to infection. The pivotal role of the liver in metabolic, synthetic, and immunological pathways enforces limits the host's ability to control the immune response appropriately, making it vulnerable to ineffective pathogen resistance and tissue damage. Deregulated networks of liver diseases are gradually uncovered by high-throughput, single-cell resolved OMICS technologies visualizing an astonishing diversity of cell types and regulatory interaction driving tolerogenic signaling in health and inflammation in disease. Therefore, this review elucidates the effects of the dysregulated host response on the liver, consequences for the immune response, and possible avenues for personalized therapeutics.

Biochemical information from activated leukocytes provide valuable diagnostic information. In this study, Raman spectroscopy was applied as a label-free analytical technique to characterize the activation pattern of leukocyte subpopulations in an in vitro infection model. Neutrophils, monocytes, and lymphocytes were isolated from healthy volunteers and stimulated with heat-inactivated clinical isolates of Candida albicans, Staphylococcus aureus, and Klebsiella pneumoniae. Binary classification models could identify the presence of infection for monocytes and lymphocytes, classify the type of infection as bacterial or fungal for neutrophils, monocytes, and lymphocytes and distinguish the cause of infection as Gram-negative or Gram-positive bacteria in the monocyte subpopulation. Changes in single-cell Raman spectra, upon leukocyte stimulation, can be explained with biochemical changes due to the leukocyte’s specific reaction to each type of pathogen. Raman spectra of leukocytes from the in vitro infection model were compared with spectra from leukocytes of patients with infection (DRKS-ID: DRKS00006265) with the same pathogen groups, and a good agreement was revealed. Our study elucidates the potential of Raman spectroscopy-based single-cell analysis for the differentiation of circulating leukocyte subtypes and identification of the infection by probing the molecular phenotype of those cells.