Targeted brain delivery of RVG29-modified rifampicin-loaded nanoparticles for Alzheimer's disease treatment and diagnosis.

Alzheimer's disease (AD) is an aging-related neurodegenerative disease. The main pathological features of AD are ß-amyloid protein (Aß) deposition and tau protein hyperphosphorylation. Currently, there are no effective drugs for the etiological treatment of AD. Rifampicin (RIF) is a semi-synthetic broad-spectrum antibiotic with anti-ß-amyloid deposition, anti-inflammatory, anti-apoptosis, and neuroprotective effects, but its application in AD treatment has been limited for its strong hydrophobicity, high toxicity, short half-life, low bioavailability, and blood-brain barrier hindrance. We designed a novel brain-targeted and MRI-characteristic nanomedicine via loading rabies virus protein 29 (RVG29), rifampicin, and Gd on poly (l-lactide) nanoparticles (RIF@PLA-PEG-Gd/Mal-RVG29). The cytotoxicity assay demonstrated that RIF@PLA-PEG-Gd/Mal-RVG29 had favorable biocompatibility and security. Fluorescence imaging in vivo showed that PLA-PEG-Gd/Mal-RVG29 could deliver rifampicin into the brain by enhancing cellular uptake and brain targeting performance, leading to improvement of the bioavailability of rifampicin. In in vivo study, RIF@PLA-PEG-Gd/Mal-RVG29 improved the spatial learning and memory capability of APP/PS1 mice in the Morris water maze, as compared to rifampicin. Immunofluorescence, TEM, immunoblotting, and H&E staining revealed that RIF@PLA-PEG-Gd/Mal-RVG29 reduced Aß deposition in hippocampal and cortex of APP/PS1 mice, improved the damage of synaptic ultrastructure, increased the expression level of PSD95 and SYP, as well as reduced the necrosis of neurons. These findings suggest that RIF@PLA-PEG-Gd/Mal-RVG29 may be an effective strategy for the treatment of AD.

Dl-butylphthalide inhibits rotenone-induced oxidative stress in microglia via regulation of the Keap1/Nrf2/HO-1 signaling pathway.

Activated microglia are a source of superoxide which often increases oxidative stress in the brain microenvironment, increase production of reactive oxygen species (ROS) and directly or indirectly lead to dopaminergic neuronal death in the substantia nigra. Thus superoxide contributes to the pathogenesis of Parkinson's disease (PD). Evidence suggests that mitochondria are the main source of ROS, which cause oxidative stress in cells. Levels of ROS are thus associated with the function of the mitochondrial complex. Therefore, protecting the mitochondrial function of microglia is important for the treatment of PD. Dl-butylphthalide (NBP), a compound isolated from Chinese celery seeds, has been approved by the China Food and Drug Administration for the treatment of acute ischemic stroke. Recently, NBP demonstrated therapeutic potential for PD. However, the mechanism underlying its neuroprotective effect remains unclear. The present study aimed to investigate the effect of NBP on rotenone-induced oxidative stress in microglia and its underlying mechanisms. The results demonstrated that NBP treatment significantly increased mitochondrial membrane potential and decreased ROS level in rotenone-induced microglia. Western blot analysis showed that NBP treatment promoted entry of nuclear respiratory factor-2 (Nrf2) into the nucleus, increased heme oxygenase-1 (HO-1) expression and decreased the level of the Nrf2 inhibitory protein, Kelch-like ECH-associated protein 1. Overall, the findings indicated that NBP inhibited rotenone-induced microglial oxidative stress via the Keap1/Nrf2/HO-1 pathway, suggesting that NBP may serve as a novel agent for the treatment of PD.

Rifampicin ameliorates lipopolysaccharide-induced cognitive and motor impairments via inhibition of the TLR4/MyD88/NF-κB signaling pathway in mice.

OBJECTIVES: Aberrant microglial responses promote neuroinflammation in neurodegenerative diseases. However, rifampicin's effect on cognitive and motor sequelae of inflammation remains unknown. Therefore, we investigated whether rifampicin exerts neuroprotection against lipopolysaccharide (LPS)-induced cognitive and motor impairments. METHODS: A mouse model of LPS-induced cognitive and motor impairment was established. Adult C57BL/6 mice were injected intraperitoneally with 25 mg/kg rifampicin 30 min before intraperitoneal microinjection of LPS (750 µg/kg) daily until study end. Treatments and behavioral experiments were performed once daily for 7 days. Behavioral tests and pathological/biochemical assays were performed to evaluate LPS-induced damage to the hippocampus and substantia nigra (SN). RESULTS: Rifampicin attenuated LPS-induced cognitive and motor impairments, based on performance in the behavioral tests. Rifampicin suppressed the release of pro-inflammatory mediators, including tumor necrosis factor-α, interleukin-1ß, and prostaglandin E2 in the serum and nitric oxide (NO) in brain tissue, and cyclooxygenase-2 and inducible nitric oxide synthase levels. Immunofluorescence revealed that rifampicin inhibited LPS-induced microglial activation in the hippocampus and SN, thus protecting the neurons. Rifampicin inhibited the activation of the toll-like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88)/nuclear factor kappa B (NF-κB) signaling pathway. Rifampicin downregulated TLR4 and MyD88 protein levels and inhibited NF-κB inhibitor alpha and NF-κB inhibitor kinase beta phosphorylation, thus reducing p65 nuclear transfer by inhibiting NF-κB signaling activation in LPS-treated mice. CONCLUSION: Rifampicin protects against LPS-induced neuroinflammation and attenuates cognitive and motor impairments by inhibiting the TLR4/MyD88/NF-κB signaling pathway. Our findings might aid the development of novel therapies to treat progressive neurodegenerative diseases.

Rifampicin Suppresses Amyloid-ß Accumulation Through Enhancing Autophagy in the Hippocampus of a Lipopolysaccharide-Induced Mouse Model of Cognitive Decline.

BACKGROUND: Alzheimer's disease (AD) is characterized by amyloid-ß (Aß) deposition. The metabolism of Aß is critically affected by autophagy. Although rifampicin is known to mediate neuroinflammation, the underlying mechanism by which rifampicin regulates the cognitive sequelae remains unknown. OBJECTIVE: Based on our previous findings that rifampicin possesses neuroprotective effects on improving cognitive function after neuroinflammation, we aimed to examine in this study whether rifampicin can inhibit Aß accumulation by enhancing autophagy in a mouse model of lipopolysaccharide (LPS)-induced cognitive impairment. METHODS: Adult C57BL/6 mice were intraperitoneally injected with rifampicin, chloroquine, and/or LPS every day for 7 days. Pathological and biochemical assays and behavioral tests were performed to determine the therapeutic effect and mechanism of rifampicin on the hippocampus of LPS-induced mice. RESULTS: We found that rifampicin ameliorated cognitive impairments in the LPS-induced mice. In addition, rifampicin attenuated the inhibition of autophagosome formation, suppressed the accumulation of Aß1-42, and protected the hippocampal neurons against LPS-induced damage. Our results further demonstrated that rifampicin improved the neurological function by promoting autophagy through the inhibition of Akt/mTOR/p70S6K signaling pathway in the hippocampus of LPS-induced mice. CONCLUSION: Rifampicin ameliorates cognitive impairment by suppression of Aß1-42 accumulation through inhibition of Akt/mTOR/p70S6K signaling and enhancement of autophagy in the hippocampus of LPS-induced mice.

Inhibition of Caspase-1 Ameliorates Ischemia-Associated Blood-Brain Barrier Dysfunction and Integrity by Suppressing Pyroptosis Activation.

Ischemic cerebral infarction represents a significant cause of disability and death worldwide. Caspase-1 is activated by the NLRP3/ASC pathway and inflammasomes, thus triggering pyroptosis, a programmed cell death. In particular, this death is mediated by gasdermin D (GSDMD), which induces secretion of interleukin (IL)-1ß and IL-18. Accordingly, inhibition of caspase-1 prevents the development and worsening of multiple neurodegenerative diseases. However, it is not clear whether inhibition of caspase-1 can preserve blood-brain barrier (BBB) integrity following cerebral infarction. This study therefore aimed at understanding the effect of caspase-1 on BBB dysfunction and its underlying mechanisms in permanent middle cerebral artery occlusion (MCAO). Our findings in rat models revealed that expression of caspase-1 was upregulated following MCAO-induced injury in rats. Consequently, pharmacologic inhibition of caspase-1 using vx-765 ameliorated ischemia-induced infarction, neurological deficits, and neuronal injury. Furthermore, inhibition of caspase-1 enhanced the encapsulation rate of pericytes at the ischemic edge, decreased leakage of both Evans Blue (EB) and matrix metalloproteinase (MMP) proteins, and upregulated the levels of tight junctions (TJs) and tissue inhibitors of metalloproteinases (TIMPs) in MCAO-injured rats. This in turn improved the permeability of the BBB. Meanwhile, vx-765 blocked the activation of ischemia-induced pyroptosis and reduced the expression level of inflammatory factors such as caspase-1, NLRP3, ASC, GSDMD, IL-1ß, and IL-18. Similarly, vx-765 treatment significantly reduced the expression levels of inflammation-related receptor for advanced glycation end products (RAGE), high-mobility family box 1 (HMGB1), mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB). Evidently, inhibition of caspase-1 significantly improves ischemia-associated BBB permeability and integrity by suppressing pyroptosis activation and the RAGE/MAPK pathway.

Neuroprotective mechanisms of 3-n-butylphthalide in neurodegenerative diseases.

Since 3-n-butylphthalide (NBP) was approved by the China Food and Drug Administration for the treatment of acute ischemia stroke in 2002, a number of studies have investigated NBP worldwide. In recent years, NBP has also demonstrated potential as treatment of several neurodegenerative diseases, which has increased the interest in its mechanisms of protection and action. Clinical studies and studies that used cell or animal models, have directly demonstrated neuroprotective effects of NBP via the following mechanisms: i) Inhibiting the inflammatory reaction; ii) reducing mitochondrial oxidative stress; iii) regulating apoptosis and autophagy; iv) inducing resistance to endoplasmic reticulum stress; and v) decreasing abnormal protein deposition. Therefore, NBP may be a potential drug for neurodegenerative diseases, and it is particularly important to identify the mechanism of NBP as it may assist with the development of new drugs for neurodegeneration. The present review summarizes the neuroprotective mechanisms of NBP and discusses new perspectives and prospects. The aim of the current review is to provide a new summary regarding NBP and its associated mechanisms.