ISO-alpha-acids improve the hematoma resolution and prevent peri-hematoma inflammations by transforming microglia via PPARgamma-CD36 axis in ICH rats

Drug delivery nanoparticles for preventing implant bacterial infections based on the bacteria and immunity mechanisms

Implant dysfunction and failure during medical treatment can be attributed to bacterial infection with Staphylococcus aureus and Enterococcus faecalis, which are the prevalent strains responsible for implant infections. Currently, antibiotics are primarily used either locally or systemically to prevent and treat bacterial infections in implants. However, the effectiveness of this approach is unsatisfactory. Therefore, the development of new antimicrobial medications is crucial to address the clinical challenges associated with implant infections. In this study, a nanoparticle (ICG+RSG) composed of indocyanine green (ICG) and rosiglitazone (RSG), and delivered using 1,2-dipalmitoyl-snglycero-3-phosphocholine (DPPC) was prepared. ICG+RSG has photothermal and photodynamic properties to eliminate bacteria at the infection site by releasing reactive oxygen species and increasing the temperature. Additionally, it regulates phagocytosis and macrophage polarization to modulate the immune response in the body. ICG+RSG kills bacteria and reduces tissue inflammation, showing potential for preventing implant infections.

Modulating the polarization phenotype of microglia - A valuable strategy for central nervous system diseases

Central nervous system (CNS) diseases have become one of the leading causes of death in the global population. The pathogenesis of CNS diseases is complicated, so it is important to find the patterns of the disease to improve the treatment strategy. Microglia are considered to be a double-edged sword, playing both harmful and beneficial roles in CNS diseases. Therefore, it is crucial to understand the progression of the disease and the changes in the polar phenotype of microglia to provide guidance in the treatment of CNS diseases. Microglia activation may evolve into different phenotypes: M1 and M2 types. We focused on the roles that M1 and M2 microglia play in regulating intercellular dialogues, pathological reactions and specific diseases in CNS diseases. Importantly, we summarized the strategies used to modulate the polarization phenotype of microglia, including traditional pharmacological modulation, biological therapies, and physical strategies. This review will contribute to the development of potential strategies to modulate microglia polarization phenotypes and provide new alternative therapies for CNS diseases.

Pre-treatment of rapamycin transformed M2 microglia alleviates traumatic cervical spinal cord injury via AIM2 signaling pathway in vitro and in vivo

BACKGROUND

Traumatic spinal cord injury (SCI) is still devastating. It was suggested that the inhibition of mTOR may alleviate neuronal inflammatory injury but its underlying mechanism remained to be elucidated. AIM2 (absent in melanoma 2) recruits ASC (apoptosis-associated speck-like protein containing a CARD) and caspase-1 to form the AIM2 inflammasome, activate caspase-1, and elicit inflammatory responses. We designed this study to elucidate whether pre-treatments of rapamycin could suppress SCI induced neuronal inflammatory injury via AIM2 signaling pathway in vitro and in vivo.

METHODS

We performed oxygen and glucose deprivation / re-oxygenation (OGD) treatment and rats clipping model to mimic neuronal injury after SCI in vitro and in vivo. Morphologic changes of injured spinal cord were detected by hematoxylin and eosin staining. The expression of mTOR, p-mTOR, AIM2, ASC, Caspase-1 and et al were analyzed by fluorescent staining, western blotting or qPCR. The polarization phenotype of microglia was identified by flow cytometry or fluorescent staining.

RESULTS

We found BV-2 microglia without any pre-treatment cannot alleviate primary cultured neuronal OGD injury. However, pre-treated rapamycin in BV-2 cells could transform microglia to M2 phenotype and protects against neuronal OGD injury via AIM2 signaling pathway. Similarly, pre-treatment of rapamycin could improve the outcome of cervical SCI rats through AIM2 signaling pathway.

CONCLUSIONS

It was suggested that resting state microglia pre-treated by rapamycin could protect against neuronal injury via AIM2 signaling pathway in vitro and in vivo. Pre-inhibition of mTOR pathway may improve neuronal protection after SCI.

Magnetic Targeting Nanocarriers Combined with Focusing Ultrasound for Enhanced Intracerebral Hemorrhage Therapy

Intracerebral hemorrhage (ICH) remains a significant cause of morbidity and mortality around the world, and surgery is still the most direct and effective way to remove ICH. However, the potential risks brought by surgery, such as normal brain tissue damage, post-operative infection, and difficulty in removing deep hematoma, are still the main problems in the surgical treatment of ICH. Activation of the peroxisome proliferator-activated receptor gamma (PPARγ) is reported to show a good therapeutic effect in hematoma clearance. Herein, a magnetic targeting nanocarrier loaded with a PPARγ agonist (15d-PGJ2-MNPs) is synthesized, which could be magnetically targeted and enriched in the area of the hematoma after intravenous injection. Subsequent application of focusing ultrasound (FUS) could enhance drug diffusion, which activates the PPARγ receptors on macrophages around the hematoma for better hematoma clearance. The 15d-PGJ2-MNP treatment alleviates brain injury, accelerates hematoma clearance, attenuates neuroinflammation, reduces brain edema and significantly improves the deficits in sensory and motor function and spatial learning ability in the ICH mouse model. This work proposes an effective magnetic targeting plus FUS method to treat ICH, highlighting its great potential in the treatment of hemorrhagic stroke.

Research progress of endogenous hematoma absorption after intracerebral hemorrhage

Non-traumatic intraparenchymal brain hemorrhage is referred to as intracerebral hemorrhage (ICH). Although ICH is associated with a high rate of disability and case fatality, active intervention can significantly lower the rate of severe disability. Studies have shown that the speed of hematoma clearance after ICH determines the patient's prognosis. Following ICH, depending on the hematoma volume and mass effect, either surgical- or medication-only conservative treatment is chosen. The goal of promoting endogenous hematoma absorption is more relevant because surgery is only appropriate for a small percentage of patients, and open surgery can cause additional trauma to patients. The primary method of removing hematoma after ICH in the future will involve understanding how to produce and manage macrophage/microglial endogenous phagocytic hematomas. Therefore, it is necessary to elucidate the regulatory mechanisms and key targets for clinical purposes.

The Critical Role of Erythrolysis and Microglia/Macrophages in Clot Resolution After Intracerebral Hemorrhage: A Review of the Mechanisms and Potential Therapeutic Targets

Intracerebral hemorrhage (ICH) is a common cerebrovascular disorder with high morbidity and mortality. Secondary brain injury after ICH, which is initiated by multiple hemolytic products during erythrolysis, has been identified as a critical factor accounting for the poor prognosis of ICH patients. Clot resolution and hematoma clearance occur immediately after ICH via erythrolysis and erythrophagocytosis. During this process, erythrolysis after ICH results in the release of hemoglobin and products of degradation along with rapid morphological changes in red blood cells (RBCs). Phagocytosis of deformed erythrocytes and products of degradation by microglia/macrophages accelerates hematoma clearance, which turns out to be neuroprotective. Thus, a better understanding of the mechanism of erythrolysis and the role of microglia/macrophages after ICH is urgently needed. In this review, the current research progresses on the underlying mechanism of erythrolysis and erythrophagocytosis, as well as several useful tools for the quantification of erythrolysis-induced brain injury, are summarized, providing potential intervention targets and possible treatment strategies for ICH patients.

Kinetics of monocyte subpopulations during experimental cerebral malaria and its resolution in a model of late chloroquine treatment

Cerebral malaria (CM) is one of the most severe forms of malaria and is a neuropathology that can lead to death. Monocytes have been shown to accumulate in the brain microvasculature at the onset of neurological symptoms during CM. Monocytes have a remarkable ability to adapt their function to their microenvironment from pro-inflammatory to resolving activities. This study aimed to describe the behavior of monocyte subpopulations during infection and its resolution. C57BL/6 mice were infected with the Plasmodium berghei ANKA strain and treated or not with chloroquine (CQ) on the first day of the onset of neurological symptoms (day 6) for 4 days and followed until day 12 to mimic neuroinflammation and its resolution during experimental CM. Ly6C monocyte subpopulations were identified by flow cytometry of cells from the spleen, peripheral blood, and brain and then quantified and characterized at different time points. In the brain, the Ly6C^int and Ly6C^low monocytes were associated with neuroinflammation, while Ly6C^hi and Ly6C^int were mobilized from the peripheral blood to the brain for resolution. During neuroinflammation, CD36 and CD163 were both involved via splenic monocytes, whereas our results suggest that the low CD36 expression in the brain during the neuroinflammation phase was due to degradation. The resolution phase was characterized by increased expressions of CD36 and CD163 in blood Ly6C^low monocytes, a higher expression of CD36 in the microglia, and restored high expression levels of CD163 in Ly6C^hi monocytes localized in the brain. Thus, our results suggest that increasing the expressions of CD36 and CD163 specifically in the brain during the neuroinflammatory phase contributes to its resolution.

Curcumin Restrains Oxidative Stress of After Intracerebral Hemorrhage in Rat by Activating the Nrf2/HO-1 Pathway

Intracerebral hemorrhage (ICH), a severe hemorrhagic stroke, induces cerebral oxidative stress and severe secondary neurological injury. Curcumin was demonstrated to inhibit oxidative stress in the brain after ICH. However, the pharmacological mechanism needs further research. We used an intrastriatal injection of autologous blood to make the rat ICH model, and then the rat was treated with curcumin (100 mg/kg/day). Modified Neurological Severity Score (mNSS) and corner test results showed that curcumin could significantly promote the neurological recovery of ICH rats. Meanwhile, curcumin could substantially reduce ROS and MDA in the tissues around intracranial hematoma and prevent GSH depletion. To explore the pharmacological molecular mechanism of curcumin, we used HAPI cells and primary rat cortical microglia for in vitro experiments. In vitro, heme-treated cells were used as the cell model of ICH to explore the molecular mechanism of inhibiting oxidative stress by curcumin treatment. The results showed that curcumin significantly inhibited heme-induced oxidative stress, decreased intracellular ROS and MDA, and promoted Nrf2 and its downstream antioxidant gene (HO-1, NQO1, and Gpx4) expression. These results suggest that curcumin inhibits oxidative stress by activating the Nrf2/HO-1 pathway. Here, our results indicate that curcumin can promote the inhibition of oxidative stress in microglia by activating the Nrf2/HO-1 pathway and promoting neurological recovery after ICH, providing a new therapeutic target for clinical treatment of ICH.

Activation of the PPARγ Prevents Ferroptosis-Induced Neuronal Loss in Response to Intracerebral Hemorrhage Through Synergistic Actions With the Nrf2

Intracerebral hemorrhage (ICH) is a subtype of stroke characterized by high mortality and disability rates. The long-term effects of ICH-induced intracranial hematoma on patients’ neurological function are unclear. Currently, an effective treatment that significantly reduces the rates of death and disability in patients with ICH is not available. Based on accumulating evidence, ferroptosis may be the leading factor contributing to the neurological impairment caused by ICH injury. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated receptor in the nuclear hormone receptor family that synergistically interacts with the nuclear factor erythrocyte 2-related factor 2 (Nrf2) pathway to promote the expression of related genes and inhibit ferroptosis. Primary rat hippocampal neurons were treated with heme (50 μM) and erastin (50 μM) to induce ferroptosis, followed by the PPARγ agonist pioglitazone (PDZ, 10 μM) to verify the inhibitory effect of PPARγ activation on ferroptosis. ML385 (2 μM), a novel and specific NRF2 inhibitor, was administered to the inhibitor group, followed by an analysis of cellular activity and immunofluorescence staining. In vivo Assays, ICH rats injected with autologous striatum were treated with 30 mg/kg/d pioglitazone, and the inhibitor group was injected with ML385 (30 mg/kg). The results showed that PDZ inhibited ferroptosis in neurons by increasing the expression of PPARγ, Nrf2 and Gpx4 in vitro, while PDZ reduced ferroptosis in neurons after ICH and promoted the recovery of neural function in vivo. Our results suggest that PDZ, a PPARγ agonist, promotes Gpx4 expression through the interaction between PPARγ and the Nrf2 pathway, inhibits ferroptosis of neurons after ICH, and promotes the recovery of neural function.

Erythrophagocytosis by Microglia/Macrophage in Intracerebral Hemorrhage: From Mechanisms to Translation

Intracerebral hemorrhage (ICH) is a devastating condition characterized by hematoma related mass effect. Microglia/macrophage (M φ) are rapidly recruited in order to remove the red blood cells through erythrophagocytosis. Efficient erythrophagocytosis can detoxify hemolytic products and facilitate neurological recovery after ICH. The underlying mechanisms include modulation of inflammatory response and oxidative stress, among others. It is a dynamic process mediated by a cascade of signal transduction, including “find-me” signals, “eat-me” signals and a set of phagocytotic receptors-ligand pairs that may be exploited as therapeutic targets. This review summarizes mechanistic signaling pathways of erythrophagocytosis and highlights the potential of harnessing M φ-mediated phagocytosis for ICH treatment.

p53 Inhibition Protects against Neuronal Ischemia/Reperfusion Injury by the p53/PRAS40/mTOR Pathway

The underlying mechanisms of cerebral ischemia/reperfusion (I/R) injury are unclear. Within this study, we aimed to explore whether p53 inhibition exerts protective effects via the p53/PRAS40/mTOR pathway after stroke and its potential mechanism. Both an in vitro oxygen-glucose deprivation (OGD) model with a primary neuronal culture and in vivo stroke models (dMCAO or MCAO) were used. We found that the infarction size, neuronal apoptosis, and autophagy were less severe in p53 KO mice and p53 KO neurons after cerebral I/R or OGD/R injury. By activating the mTOR pathway, p53 knockdown alleviated cerebral I/R injury both in vitro and in vivo. When PRAS40 was knocked out, the regulatory effects of p53 overexpression or knockdown against stroke disappeared. PRAS40 knockdown could inhibit the activities of the mTOR pathway; moreover, neuronal autophagy and apoptosis were exacerbated by PRAS40 knockdown. To sum up, in this study, we showed p53 inhibition protects against neuronal I/R injury after stroke via the p53/PRAS40/mTOR pathway, which is a novel and pivotal cerebral ischemic injury signaling pathway. The induction of neuronal autophagy and apoptosis by the p53/PRAS40/mTOR pathway may be the potential mechanism of this protective effect.

Hypoxia-preconditioned mesenchymal stem cells attenuate microglial pyroptosis after intracerebral hemorrhage

Background

Microglia plays a vital role in neuroinflammation, contributing to the pathogenesis of intracerebral hemorrhage (ICH)-induced brain injury. Mesenchymal stem cells (MSCs) hold great potential for treating ICH. We previously revealed that MSCs ameliorate the microglial pyroptosis caused by an ischemic stroke. However, whether MSCs can modulate microglial pyroptosis after ICH remains unknown. This study aimed to investigate the neuroprotective effects of hypoxia-preconditioned olfactory mucosa MSCs (OM-MSCs) on ICH and the possible mechanisms.

Methods

ICH was induced in mice via administration of collagenase IV. At 6 h post-ICH, 2-4×10⁵ normoxic/hypoxic OM-MSCs or saline were intracerebrally administered. To evaluate the neuroprotective effects, the behavioral outcome, apoptosis, and neuronal injury were measured. Microglia activation and pro-inflammatory cytokines were applied to detect neuroinflammation. Microglial pyroptosis was determined by western blotting, immunofluorescence staining, and transmission electron microscopy (TEM).

Results

The two OM-MSC-transplanted groups exhibited significantly improved functional recovery and reduced neuronal injury, especially the hypoxic OM-MSCs group. Hypoxic OM-MSCs attenuated microglial activation as well as the levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Moreover, we found that hypoxia-preconditioned OM-MSCs ameliorated pyroptosis by diminishing the levels of pyroptosis-associated proteins in peri-hematoma brain tissues, decreasing the expression of the microglial nod-like receptor family protein 3 (NLRP3) and caspase-1, and reducing the membrane pores on microglia post-ICH.

Conclusions

Our study showed that hypoxic preconditioning augments the therapeutic efficacy of OM-MSCs, and hypoxia-preconditioned OM-MSCs alleviate microglial pyroptosis in the ICH model.

Redox and Anti-Inflammatory Properties from Hop Components in Beer-Related to Neuroprotection

Beer is a fermented beverage widely consumed worldwide with high nutritional and biological value due to its bioactive components. It has been described that both alcoholic and non-alcoholic beer have several nutrients derived from their ingredients including vitamins, minerals, proteins, carbohydrates, and antioxidants that make beer a potential functional supplement. Some of these compounds possess redox, anti-inflammatory and anticarcinogenic properties making the benefits of moderate beer consumption an attractive way to improve human health. Specifically, the hop cones used for beer brewing provide essential oils, bitter acids and flavonoids that are potent antioxidants and immune response modulators. This review focuses on the redox and anti-inflammatory properties of hop derivatives and summarizes the current knowledge of their neuroprotective effects.