miRNA-5119 regulates immune checkpoints in dendritic cells to enhance breast cancer immunotherapy.

Dendritic cell (DC) based immunotherapy is a promising approach to clinical cancer treatment. miRNAs are a class of small non-coding RNA molecules that bind to RNAs to mediate multiple events which are important in diverse biological processes. miRNA mimics and antagomirs may be potent agents to enhance DC-based immunotherapy against cancers. miRNA array analysis was used to identify a representative miR-5119 potentially regulating PD-L1 in DCs. We evaluated levels of ligands of immune cell inhibitory receptors (IRs) and miR-5119 in DCs from immunocompetent mouse breast tumor-bearing mice, and examined the molecular targets of miR-5119. We report that miRNA-5119 was downregulated in spleen DCs from mouse breast cancer-bearing mice. In silico analysis and qPCR data showed that miRNA-5119 targeted mRNAs encoding multiple negative immune regulatory molecules, including ligands of IRs such as PD-L1 and IDO2. DCs engineered to express a miR-5119 mimic downregulated PD-L1 and prevented T cell exhaustion in mice with breast cancer homografts. Moreover, miR-5119 mimic-engineered DCs effectively restored function to exhausted CD8+ T cells in vitro and in vivo, resulting in robust anti-tumor cell immune response, upregulated cytokine production, reduced T cell apoptosis, and exhaustion. Treatment of 4T1 breast tumor-bearing mice with miR-5119 mimic-engineered DC vaccine reduced T cell exhaustion and suppressed mouse breast tumor homograft growth. This study provides evidence supporting a novel therapeutic approach using miRNA-5119 mimic-engineered DC vaccines to regulate inhibitory receptors and enhance anti-tumor immune response in a mouse model of breast cancer. miRNA/DC-based immunotherapy has potential for advancement to the clinic as a new strategy for DC-based anti-breast cancer immunotherapy.

Effect of Quercetin on Atherosclerosis Based on Expressions of ABCA1, LXR-α and PCSK9 in ApoE-/- Mice.

OBJECTIVE: To investigate the effect of quercetin on ATP binding cassette transporter A1 (ABCA1), liver X receptor (LXR), and proprotein convertase subtilisin/kexin type 9 (PCSK9) expressions in apoE-knockout (ApoE-/-) mice. METHODS: The high-fat diet-induced atherosclerosis (AS) in ApoE-/- mice was established. Thirty-six mice were divided into 3 groups using random number table method: model group (n=12), quercetin group (n=12), and atorvastatin group (n=12), with C57BL/6J mice of the same strain and age as the control group (n=12). Quercetin group and atorvastatin group were administrated with quercetin and atorvastatin by oral gavage, with doses of 12.5 and 4 mg/(kg•d), respectively. Animals in the control and model groups were given an equal volume of distilled water by oral gavage once per day for a total of 12 weeks. Western blot and immunohistochemical methods were employed to determine the aortic ABCA1, LXR-α and PCSK9 protein expression. Enzyme linked immunosorbent assay method was used to detect the expression of serum total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-10, combined with tissue pathological examination. RESULTS: ApoE-/- mice fed with a high-fat diet had notable atherosclerosis lesions, with reduced ABCA1, LXR-α and IL-10 levels (all P<0.01), elevated PCSK9, TNF-α and IL-6 expression, and increased TC and LDL-C contents (all P<0.01). After quercetin intervention, the areas of AS plaques and the expressions of PCSK9, TNF-α and IL-6 were significantly reduced (all P<0.01), while the expressions of ABCA1 and LXR-α were increased significantly (all P<0.01). CONCLUSION: Quercetin effectively interfered with AS development by regulating the expressions of ABCA1, LXR- α and PCSK9 in ApoE-/- mice.

Glutamine synthetase down-regulation reduces astrocyte protection against glutamate excitotoxicity to neurons.

Although the role of astrocyte glutamate transporters in glutamate clearance is well illustrated, the role of glutamine synthetase (GS) that influences this process remains to be elucidated. We examined whether GS affected the uptake of glutamate in astrocytes in vitro. The glutamate uptake was assessed by measuring the concentration of glutamate and glutamine in culture medium in the presence or absence of glutamate. We demonstrated that inhibition of GS in astrocytes by MSO significantly impaired glutamate uptake and glutamine release. Conversely, induction of GS expression in astrocytes by gene transfer significantly enhanced the glutamate uptake and glutamine release. When an inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) was applied to the cultures, it significantly reduced GS expression and inhibited glutamate-induced GS activation resulting in increased excitotoxicity to neurons. These results suggest that GS in astrocytes may represent a novel target for neuroprotection against neuronal dysfunction and death that occur in many neurological disorders.