The liver is a major barrier for site-specific delivery of systemically injected nanoparticles, as up to 90% of the dose is usually captured by this organ. Kupffer cells are thought to be the main cellular component responsible for nanoparticle accumulation in the liver. These resident macrophages form part of the mononuclear phagocyte system, which recognizes and engulfs foreign bodies in the circulatory system. In this study, we have compared two strategies for reducing nanoparticle accumulation in the liver, in order to investigate the specific contribution of Kupffer cells. Specifically, we have performed a comparison of the capability of pegylation and Kupffer cell depletion to reduce liposome accumulation in the liver. Pegylation reduces nanoparticle interactions with all types of cells and can serve as a control for elucidating the role of specific cell populations in liver accumulation. The results indicate that liposome pegylation is a more effective strategy for avoiding liver uptake compared to depletion of Kupffer cells, suggesting that nanoparticle interactions with other cells in the liver may also play a contributing role. This study highlights the need for a more complete understanding of factors that mediate nanoparticle accumulation in the liver and for the exploration of microenvironmental modulation strategies for reducing nanoparticle-cell interactions in this organ.

Lysosomal storage diseases, including mucopolysaccharidoses, result from genetic defects that impair lysosomal catabolism. Here, we describe two patients from two independent families presenting with progressive psychomotor regression, delayed myelination, brain atrophy, neutropenia, skeletal abnormalities, and mucopolysaccharidosis‐like dysmorphic features. Both patients were homozygous for the same intronic variant in VPS16, a gene encoding a subunit of the HOPS and CORVET complexes. The variant impaired normal mRNA splicing and led to an ~85% reduction in VPS16 protein levels in patient‐derived fibroblasts. Levels of other HOPS/CORVET subunits, including VPS33A, were similarly reduced, but restored upon re‐expression of VPS16. Patient‐derived fibroblasts showed defects in the uptake and endosomal trafficking of transferrin as well as accumulation of autophagosomes and lysosomal compartments. Re‐expression of VPS16 rescued the cellular phenotypes. Zebrafish with disrupted vps16 expression showed impaired development, reduced myelination, and a similar accumulation of lysosomes and autophagosomes in the brain, particularly in glia cells. This disorder resembles previously reported patients with mutations in VPS33A, thus expanding the family of mucopolysaccharidosis‐like diseases that result from mutations in HOPS/CORVET subunits.

The global emergence of extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E. coli), mainly causing urinary tract infections (UTI), is a major threat to human health. ESBL-E. coli sequence type (ST) 131 is the dominating clone worldwide, especially its subclade C2. Patients developing recurrent UTI (RUTI) due to ST131 subclade C2 appear to have an increased risk of recurrent infections. We have thus compared the whole genome of ST131 subclade C2 isolates from 14 patients with RUTI to those from 14 patients with sporadic UTI (SUTI). We aimed to elucidate if isolates causing RUTI can be associated with specific genomic features. Paired isolates from patients with RUTI were identical, presenting 2-18 single nucleotide polymorphism (SNP) differences for all six patients investigated. Comparative genomic analyses, including virulence factors, antibiotic resistance, pangenome and SNP analyses did not find any pattern associated with isolates causing RUTI. Despite extensive whole genome analyses, an increased risk of recurrences seen in patients with UTI due to ST131 subclade C2 isolates could not be explained by bacterial genetic differences in the two groups of isolates. Hence, additional factors that could aid in identifying bacterial properties contributing to the increased risk of RUTI due to ESBL-E. coli ST131 subclade C2 remains to be explored.