Intranasal delivery of HMGB1 siRNA confers target gene knockdown and robust neuroprotection in the postischemic brain. Mol Ther. 2012;20:829-839. [PMID: 22252450 DOI: 10.1038/mt.2011.291]

High-mobility group box-1 induces decreased brain-derived neurotrophic factor-mediated neuroprotection in the diabetic retina

To test the hypothesis that brain-derived neurotrophic factor-(BDNF-) mediated neuroprotection is reduced by high-mobility group box-1 (HMGB1) in diabetic retina, paired vitreous and serum samples from 46 proliferative diabetic retinopathy and 34 nondiabetic patients were assayed for BDNF, HMGB1, soluble receptor for advanced glycation end products (sRAGE), soluble intercellular adhesion molecule-1 (sICAM-1), monocyte chemoattractant protein-1 (MCP-1), and TBARS. We also examined retinas of diabetic and HMGB1 intravitreally injected rats. The effect of the HMGB1 inhibitor glycyrrhizin on diabetes-induced changes in retinal BDNF expressions was studied. Western blot, ELISA, and TBARS assays were used. BDNF was not detected in vitreous samples. BDNF levels were significantly lower in serum samples from diabetic patients compared with nondiabetics, whereas HMGB1, sRAGE, sICAM-1, and TBARS levels were significantly higher in diabetic serum samples. MCP-1 levels did not differ significantly. There was significant inverse correlation between serum levels of BDNF and HMGB1. Diabetes and intravitreal administration of HMGB1 induced significant upregulation of the expression of HMGB1, TBARS, and cleaved caspase-3, whereas the expression of BDNF and synaptophysin was significantly downregulated in rat retinas. Glycyrrhizin significantly attenuated diabetes-induced downregulation of BDNF. Our results suggest that HMGB1-induced downregulation of BDNF might be involved in pathogenesis of diabetic retinal neurodegeneration.

Alcohol-induced IL-1β in the brain is mediated by NLRP3/ASC inflammasome activation that amplifies neuroinflammation

Alcohol-induced neuroinflammation is mediated by proinflammatory cytokines, including IL-1β. IL-1β production requires caspase-1 activation by inflammasomes-multiprotein complexes that are assembled in response to danger signals. We hypothesized that alcohol-induced inflammasome activation contributes to increased IL-1β in the brain. WT and TLR4-, NLRP3-, and ASC-deficient (KO) mice received an ethanol-containing or isocaloric control diet for 5 weeks, and some received the rIL-1ra, anakinra, or saline treatment. Inflammasome activation, proinflammatory cytokines, endotoxin, and HMGB1 were measured in the cerebellum. Expression of inflammasome components (NLRP1, NLRP3, ASC) and proinflammatory cytokines (TNF-α, MCP-1) was increased in brains of alcohol-fed compared with control mice. Increased caspase-1 activity and IL-1β protein in ethanol-fed mice indicated inflammasome activation. TLR4 deficiency protected from TNF-α, MCP-1, and attenuated alcohol-induced IL-1β increases. The TLR4 ligand, LPS, was not increased in the cerebellum. However, we found up-regulation of acetylated and phosphorylated HMGB1 and increased expression of the HMGB1 receptors (TLR2, TLR4, TLR9, RAGE) in alcohol-fed mice. NLRP3- or ASC-deficient mice were protected from caspase-1 activation and alcohol-induced IL-1β increase in the brain. Furthermore, in vivo treatment with rIL-1ra prevented alcohol-induced inflammasome activation and IL-1β, TNF-α, and acetylated HMGB1 increases in the cerebellum. Conversely, intracranial IL-1β administration induced TNF-α and MCP-1 in the cerebellum. In conclusion, alcohol up-regulates and activates the NLRP3/ASC inflammasome, leading to caspase-1 activation and IL-1β increase in the cerebellum. IL-1β amplifies neuroinflammation, and disruption of IL-1/IL-1R signaling prevents alcohol-induced inflammasome activation and neuroinflammation. Increased levels of acetylated and phosphorylated HMGB1 may contribute to alcoholic neuroinflammation.

A novel dendritic nanocarrier of polyamidoamine-polyethylene glycol-cyclic RGD for "smart" small interfering RNA delivery and in vitro antitumor effects by human ether-à-go-go-related gene silencing in anaplastic thyroid carcinoma cells

The application of RNA interference techniques is promising in gene therapeutic approaches, especially for cancers. To improve safety and efficiency of small interfering RNA (siRNA) delivery, a triblock dendritic nanocarrier, polyamidoamine-polyethylene glycol-cyclic RGD (PAMAM-PEG-cRGD), was developed and studied as an siRNA vector targeting the human ether-à-go-go-related gene (hERG) in human anaplastic thyroid carcinoma cells. Structure characterization, particle size, zeta potential, and gel retardation assay confirmed that complete triblock components were successfully synthesized with effective binding capacity of siRNA in this triblock nanocarrier. Cytotoxicity data indicated that conjugation of PEG significantly alleviated cytotoxicity when compared with unmodified PAMAM. PAMAM-PEG-cRGD exerted potent siRNA cellular internalization in which transfection efficiency measured by flow cytometry was up to 68% when the charge ratio (N/P ratio) was 3.5. Ligand-receptor affinity together with electrostatic interaction should be involved in the nano-siRNA endocytosis mechanism and we then proved that attachment of cRGD enhanced cellular uptake via RGD-integrin recognition. Gene silencing was evaluated by reverse transcription polymerase chain reaction and PAMAM-PEG-cRGD-siRNA complex downregulated the expression of hERG to 26.3% of the control value. Furthermore, gene knockdown of hERG elicited growth suppression as well as activated apoptosis by means of abolishing vascular endothelial growth factor secretion and triggering caspase-3 cascade in anaplastic thyroid carcinoma cells. Our study demonstrates that this novel triblock polymer, PAMAM-PEG-cRGD, exhibits negligible cytotoxicity, effective transfection, “smart” cancer targeting, and therefore is a promising siRNA nanocarrier.

Nonviral gene therapy in vivo with PAM-RG4/apoptin as a potential brain tumor therapeutic

Background

Glioma is still one of the most complicated forms of brain tumor to remove completely due to its location and the lack of an efficient means to specifically eliminate tumor cells. For these reasons, this study has examined the effectiveness of a nonviral gene therapy approach utilizing a tumor-selective killer gene on a brain tumor xenograft model.

Methods and results

The therapeutic apoptin gene was recombined into the JDK plasmid and delivered into human brain tumor cells (U87MG) by using a polyamidoamine dendrimer with an arginine surface (PAM-RG4). Studies in vitro showed that the PAM-RG4/apoptin plasmid polyplex exhibited a particularly high transfection activity of .40%. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, 4′,6-Diamidino-2-phenylindole (DAPI) TUNEL assay, DAPI staining, and caspase-3 activity assay verified that the tumor cells had undergone apoptosis induced by apoptin. For in vivo studies, the polyplex was injected into tumors, which were induced by injecting U87MG cells intradermally into nude mice. Based on hematoxylin and eosin staining, epidermal growth factor receptor immunohistochemistry results and tumor volume measurement results, tumor growth was effectively inhibited and no specific edema, irritation, or other harm to the skin was observed after polyplex injection. The in vivo expression of apoptin and the induction of apoptosis were verified by reverse-transcription polymerase chain reaction analysis, TUNEL assay, and DAPI staining.

Conclusion

The PAM-RG4/apoptin gene polyplex is a strong candidate for brain tumor therapeutics because of the synergistic effect of the carrier’s high transfection efficiency (35%–40%) in glioma cells and the selective apoptosis-inducing activity of apoptin in tumor cells.

Drug delivery systems for the treatment of ischemic stroke

Stroke is the third leading cause of death in the United States. Reduced cerebral blood flow causes acute damage to the brain due to excitotoxicity, reactive oxygen species (ROS), and ischemia. Currently, the main treatment for stroke is to revive the blood flow by using thrombolytic agents. Reviving blood flow also causes ischemia-reperfusion (I/R) damage. I/R damage results from inflammation and apoptosis and can persist for days to weeks, increasing the infarct size. Drugs can be applied to stroke to intervene in the sub-acute and chronic phases. Chemical, peptide, and genetic therapies have been evaluated to reduce delayed damage to the brain. These drugs have different characteristics, requiring that delivery carriers be developed based on these characteristics. The delivery route is another important factor affecting the efficiency of drug delivery. Various delivery routes have been developed, such as intravenous injection, intranasal administration, and local direct injection to overcome the blood-brain-barrier (BBB). In this review, the delivery carriers and delivery routes for peptide and gene therapies are discussed and examples are provided. Combined with new drugs, drug delivery systems will eventually provide useful treatments for ischemic stroke.

Short interfering RNA and the central nervous system: development of nonviral delivery systems

The development of gene silencing therapies for neurological diseases has placed great importance on the delivery of short interfering RNA (siRNA) to the central nervous system (CNS). However, delivery of siRNA to neurons, glia and brain capillary endothelial cells (BCECs) has not been well established. This editorial describes different approaches that are being used to efficiently deliver siRNA to the CNS via intravenous, intracerebroventricular, or intranasal administration.