No abstract

Dendritic cells (DCs) are central to innate and adaptive immunity of early kidney IRI and strategies to alter DC function may provide new therapeutic opportunities. Sphingosine 1-phosphate (S1P) modulates immunity through binding to its receptors (S1P1-5) and protection from kidney IRI occurs in S1P3-deficient mice. Through a series of experiments we determined that this protective effect was due in part to differences between S1P3-sufficient and deficient DCs. Mice lacking S1P3 on bone marrow cells were protected from IRI and S1P3-deficient DCs displayed an immature phenotype. WT but not S1P3-deficient DCs injected into mice depleted of DCs prior to kidney IR reconstituted injury. Adoptive transfer (i.e, i.v. injection) of glycolipid (antigen)-loaded WT but not S1P3-deficient DCs into WT mice exacerbated IRI, suggesting that WT but not S1P3-deficient DCs activated NKT cells. Whereas WT DC transfers activated the Th1-IFN-γ pathway, S1P3-deficient DCs activated the Th2-IL4 pathway and an IL4 blocking antibody reversed protection from IRI supporting the concept that IL-4 mediates the protective effect of S1P3-deficient DCs. Administration of S1P3-deficient DCs 7 days prior to or 3 h after IRI protected mice from IRI and suggests their potential use in cell-based therapy. We conclude that absence of DC S1P3 prevents DC maturation and promotes a Th2-IL4 response. These findings highlight the importance of DC S1P3 in modulating NKT cell function and IRI and support development of selective S1P3 antagonists for tolerizing DCs for cell based therapy or for systemic administration for the prevention and treatment of IRI and autoimmune diseases.

Recently, there has been a lot of interest in using gold nanoparticles (GNPs) for biomedical applications due to their biocompatibility. To increase GNP cell uptake and circulation half-life, and to improve its bio-distribution in vivo, we chose to coat GNPs with 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (POPG) and polyethylene glycol (PEG). Two different methods were used to synthesize POPG-GNPs or PEG-GNPs, but the resulting nanoparticle sizes and morphologies were similar. Under the same incubation conditions, POPG-GNPs can be uptaken quicker than PEG-GNPs by cells-specifically, the maximum uptake was 8 h versus 16 h after incubation. In addition, the uptake amount of POPG-GNPs was more than that of PEG-GNPs. The uptake processes were confirmed by SEM and TEM images. The main reason for the greater uptake of POPG-GNPs can be attributed to the structural similarities between the POPG coating and the cell membrane as well as GNP aggregation.

Nanotechnology is an emerging paradigm for creating functional nanoscale materials for various biomedical applications. In this study, a new nanotechnology-based drug delivery method was developed using gold nanoparticles (GNPs) as a delivery vehicle to reduce adverse drug side effects. Fludarabine Phosphate is a commercial chemotherapy drug used in cancer treatment, and has ability to kill various cancer cells. KG-1 cell, a type of acute cancer leukemia cell, was selected as a proof-of-concept target in this study. Due to the small size of GNPs, they can help Fludarabine Phosphate enter cancer cells more efficiently and better interfere with DNA synthesis in the cancer cells. To enhance targeting ability, folic acid molecules were also covalently linked to GNPs, resulting in GNP-Fludarabine-folic acid (GNP-F/f). Compared to treatments with GNP-F or drugs on its own (Fludarabine Phosphate), the GNP-F/f achieves much improved cell-killing effects. The UV-Vis spectra results also revealed that the drugs had successfully bonded covalently to the GNPs. The higher cell-killing efficiency of GNP-F/f compared with GNP-Fludarabine (GNP-F) or drugs on their own further validates the effectiveness of both the vectors (GNPs) and folic acid in enhancing the drug delivery to the cancer cells. The MTT viability tests showed that the GNPs had no cytotoxicity.

Dendritic cell (DC)-mediated nature killer T (NKT) cell activation is critical in initiating the immune response following kidney ischemia-reperfusion injury (IRI). Adenosine 2A receptor (A2AR) agonists protect kidneys from IRI through their actions on bone marrow (BM)-derived leukocytes. We hypothesized that A2AR agonists attenuate IRI by tolerizing DCs and preventing NKT cell activation. ATL313 attenuated kidney IRI in WT mice but not in mice deficient of DC A2ARs (CD11c-CreAdora2a-/-). BM-derived DCs were activated by ex vivo incubation with alpha-galactosylceramide (aGC)±ATL313 (1nM), washed and adoptively transferred into naïve WT mice 2 days before kidney IRI. ATL313-treated aGC-loaded WT DCs (DC-aGC-ATL313) but neither Adora2a-/- DC-aGC-ATL313 nor DC-aGC protected kidney function following IRI. Co-culture of NKT cells with DC-aGC-ATL313 caused less IFN-g production than with DC-aGC. ATL313 down-regulated OX40L and CD40 and up-regulated B7-DC expression but had no effect on DC surface and intracellular CD1d/aGC complexes. DC-aGC-ATL313-mediated kidney protection was not due to Treg cell expansion, but was in part due to IL-10, as IL-10mRNA level increased and IL-10 neutralization reversed the protective effect of DC-aGC-ATL313; DC-aGC-ATL313 also up-regulated PD-1 expression on co-cultured Tregs. We conclude that A2AR-induced tolerized DCs, which suppressed NKT cell activation in vivo, provide a unique and potent cell-based strategy to attenuate organ IRI.