solid-lipid-nanoparticles-slns-for-intracellular-targeting

Solid Lipid Nanoparticles (SLNs) for Intracellular Targeting Applications

Nanoparticle-based delivery vehicles have shown great promise for intracellular targeting applications, providing a mechanism to specifically alter ...

The Johns Hopkins Applied Physics Laboratory

We examined the effects of different bacterial doses of Neisseria gonorrhoeae on the cytokine response of primary human monocytes. The data indicate that a low multiplicity of infection (MOI) challenge (MOI = 0.1) results in substantial production of IL-8 and other chemokines/cytokines, in the absence of significant TNF-alpha production. Positive control challenges (MOI = 10) induced levels of IL-8 that were comparable to the low MOI challenges, but now induced significant levels of TNF-alpha. Induction of IL-8 expression in low MOI challenges was not mediated by an autocrine response as pretreatment of monocytes with neutralizing Abs against TNF-alpha or IL-1beta had no effect on IL-8 expression. IL-8 induction resulting from gonococcal challenge was shown to require NF-kappaB activation, though this activation was limited by the inoculating dose. These data indicate that IL-8 induction results from direct contact between bacteria and monocytes. Analysis of the overall cytokine profile revealed patterns of expression for growth-regulated oncogene, MCP-1, and IL-6 that were similar to IL-8. Analysis of various MAPKs indicated that low MOI challenges were able to efficiently activate both the ERK and p38 pathways, but in contrast to positive control samples, failed to activate the JNK pathway. A lack of phosphorylated JNK leads to decreased production of AP-1 dimers, transcription factors that are critical for efficient transcription of TNF-alpha. Therefore, we propose a mechanism where a low MOI gonococcal challenge results in diminished AP-1 activity and TNF-alpha production while IL-8 levels remain constant.

TNF-alpha-independent IL-8 expression: alterations in bacterial challenge dose cause differential human monocytic cytokine response.

Neisseria gonorrhoeae is an obligate human pathogen that causes significant worldwide morbidity. N. gonorrhoeae expresses lipooligosaccharide (LOS), a phase variable molecule that plays an important role during pathogenesis of the organism. Alteration in the structure of gonococcal LOS correlates with altered disease presentation. In addition, LOS sialylation occurs readily in vivo, though the role of this sialylation during disease is unknown.

Effect of gonococcal lipooligosaccharide variation on human monocytic cytokine profile.

The activity of mitochondrial complex I of the electron transport chain (ETC) is known to be affected by an extraordinarily large number of diverse xenobiotics, and dysfunction at complex I has been associated with a variety of disparate human diseases, including those with potentially environmentally relevant etiologies. However, the risks associated with mixtures of complex I inhibitors have not been fully explored, and this warrants further examination of potentially greater than additive effects that could lead to toxicity. A potential complication for the prediction of mixture effects arises because mammalian mitochondrial complex I has been shown to exist in two distinct dynamic conformations based upon substrate availability. In this study, we tested the accepted models of additivity as applied to mixtures of rotenone, deguelin, and pyridaben, with and without substrate limitation. These compounds represent both natural and synthetic inhibitors of complex I of the ETC, and experimental evidence to date indicates that these inhibitors share a common binding domain with partially overlapping binding sites. Therefore, we hypothesized that prediction of their mixtures effects would follow dose addition. Using human hepatocytes, we analyzed the effects of these mixtures at doses between 0.001 and 100 μM on overall cellular viability. Analysis of the dose-response curves resulting from challenge with all possible binary and ternary mixtures revealed that the appropriate model was not clear. All of the mixtures tested were found to be in agreement with response addition, but only rotenone plus deguelin and the ternary mixture followed dose addition. To determine if conformational regulation via substrate limitation could improve model selection and our predictions, we tested the models of additivity for the binary and ternary mixtures of inhibitors when coexposed with 2-deoxy-d-glucose (2-DG), which limits NADH via upstream inhibition of glycolysis. Coexposure of inhibitors with 2-DG did facilitate model selection: Rotenone plus pyridaben and the ternary mixture were in sole agreement with dose addition, while deguelin plus pyridaben was in sole agreement with response addition. The only ambiguous result was the agreement of both models with the mixture of rotenone plus deguelin with 2-DG, which may be explained by deguelin's well-known affinity for protein kinase B (Akt) in addition to complex I. Thus, our findings indicate that predictive models for mixtures of mitochondrial complex I inhibitors appear to be compound specific, and our research highlights the need to control for dynamic conformational changes to improve our mechanistic understanding of additivity with these inhibitors.

Julia B. Patrone

Asymmetric Operations Sector

The Johns Hopkins Applied Physics Laboratory

Solid Lipid Nanoparticles (SLNs) for Intracellular Targeting Applications

Julia B. Patrone

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Asymmetric Operations Sector

The Johns Hopkins Applied Physics Laboratory

Solid Lipid Nanoparticles (SLNs) for Intracellular Targeting Applications

Asymmetric Operations Sector