Alantolactone reduced neuron injury via activating PI3K/Akt signaling pathway after subarachnoid hemorrhage in rats

The pivotal role of microglia in injury and the prognosis of subarachnoid hemorrhage

Subarachnoid hemorrhage leads to a series of pathological changes, including vascular spasm, cellular apoptosis, blood-brain barrier damage, cerebral edema, and white matter injury. Microglia, which are the key immune cells in the central nervous system, maintain homeostasis in the neural environment, support neurons, mediate apoptosis, participate in immune regulation, and have neuroprotective effects. Increasing evidence has shown that microglia play a pivotal role in the pathogenesis of subarachnoid hemorrhage and affect the process of injury and the prognosis of subarachnoid hemorrhage. Moreover, microglia play certain neuroprotective roles in the recovery phase of subarachnoid hemorrhage. Several approaches aimed at modulating microglia function are believed to attenuate subarachnoid hemorrhage injury. This provides new targets and ideas for the treatment of subarachnoid hemorrhage. However, an in-depth and comprehensive summary of the role of microglia after subarachnoid hemorrhage is still lacking. This review describes the activation of microglia after subarachnoid hemorrhage and their roles in the pathological processes of vasospasm, neuroinflammation, neuronal apoptosis, blood-brain barrier disruption, cerebral edema, and cerebral white matter lesions. It also discusses the neuroprotective roles of microglia during recovery from subarachnoid hemorrhage and therapeutic advances aimed at modulating microglial function after subarachnoid hemorrhage. Currently, microglia in subarachnoid hemorrhage are targeted with TLR inhibitors, nuclear factor-κB and STAT3 pathway inhibitors, glycine/tyrosine kinases, NLRP3 signaling pathway inhibitors, Gasdermin D inhibitors, vincristine receptor α receptor agonists, ferroptosis inhibitors, genetic modification techniques, stem cell therapies, and traditional Chinese medicine. However, most of these are still being evaluated at the laboratory stage. More clinical studies and data on subarachnoid hemorrhage are required to improve the treatment of subarachnoid hemorrhage.

Synthetic and Pharmacological Activities of Alantolactone and Its Derivatives

Alantolactone, a sesquiterpene lactone, is isolated from the traditional Chinese medicinal herb Inula helenium L. (Asteraceae). Alantolactone is known as its wide spectrum of biological effects, including antimicrobial, antifungal, antiviral, and anthelmintic activities; anti-inflammatory activities; and antiproliferative effects on several cancer cell lines. Thus, it has received extensive attention, causing in-depth research in medicinal chemistry, and numerous undescribed alantolactone derivatives have been synthesized through different strategies. Herein, recent advances in diverse bioactivities and mechanism of alantolactone, including its derivatives, were summarized.

Molecular mechanisms of the effects of photodynamic therapy on the brain: A review of the literature

Malignant gliomas are the most common primary brain tumors in adults. These tumors have a diverse molecular origin and a very poor prognosis. There is a lack of effective treatment at WHO grade IV glioma, and all glioblastomas progress or recur. Current treatments including surgical intervention, radiation therapy, and chemotherapy are insufficient and can cause damage to healthy brain tissue and neurological deficits. The preservation of healthy brain tissue during therapeutic intervention is made extremely difficult by the ability of malignant gliomas to diffusely infiltrate the surrounding brain parenchyma. Photodynamic therapy (PDT) is a treatment modality for glioma that can possibly overcome the inherent shortcommings of traditional therapies. Photodynamic therapy involves the use of a photosensitizer (PS) which, upon absorption of light by photosensitized tissue, triggers photochemical reactions generating reactive oxygen species (ROS) leading to the killing of tumor cells. Research focusing on the effective use of PDT in the treatment of glioma is already underway with promising results. Clinical studies on PDT for the treatment of gliomas have shown it to be a safe therapeutic modality with acceptable levels of side effects. However, some adverse sequelae have been observed during PDT of these tumours, such as increased photosensitivity, increased intracranial pressure or transient aphasia and worsening of pre-existing neurological deficits. Although the clinical sequelae of PDT are well described, the molecular mechanisms of PDT's effects on the healthy brain have not yet been thoroughly characterized. In our work, we attempt to summarize the molecular mechanisms of the effects of photosensitization on neural tissue, brain vasculature and the blood-brain barrier (BBB). We also point to findings presenting molecular approaches to protect the healthy brain from the adverse effects of photodynamic damage.

Electroacupuncture improves cognitive impairment after subarachnoid hemorrhage in rats through the PI3K/AKT signaling pathway

OBJECTIVE

Cognitive impairment (CI) is highly prevalent in subarachnoid hemorrhage (SAH) patients. The phosphatidylinositol 3-kinase (PI3K)/AKT pathway plays a critical role in neuronal survival in a variety of central nervous system injuries. This study aimed to determine whether electroacupuncture (EA) at Yintang and LI20 ameliorates SAH-CI in a rat model and to examine whether it modulates the PI3K/AKT pathway by administering a PI3K inhibitor (LY294002) versus dimethyl sulfoxide (DMSO) vehicle.

METHODS

Notably, 129 male Sprague-Dawley rats were divided into Blank, Sham, SAH and SAH + EA groups (Experiment 1, n = 54) and SAH, SAH + EA, SAH + LY294002, SAH + EA + LY294002 and SAH + EA + DMSO groups (Experiment 2, n = 75). Garcia scoring was used to evaluate neurological function. The moisture content of the rat brain was determined by dry‒wet method. The Morris water maze was used to assess learning and memory function. Pathological changes in neurons in the hippocampus were observed via hematoxylin-eosin (H&E) staining. The number of surviving neurons and the percentage of apoptotic cells in the hippocampus were detected via Nissl and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. The expression of PI3K/AKT pathway-related proteins was detected via Western blotting.

RESULTS

The results indicated that EA intervention after SAH reduced brain water content, enhanced Garcia scores, improved neurological function and behavioral markers of CI, and increased the number of surviving neurons in the hippocampus. Moreover, EA significantly increased the expression of AKT, phosphorylated (p)-AKT, PI3K, p-PI3K, glycogen synthase kinase (GSK)-3β, p-GSK-3β and B cell lymphoma (Bcl)-2 proteins, and decreased the expression of Bcl-2-associated X (Bax) and caspase-3. In addition, the effects of EA were abolished by LY294002.

CONCLUSION

EA appeared to improve CI in a rat model of SAH through the activation of the PI3K/AKT pathway.

Putative Identification of 47 Compounds from Jieyu Anshen Granule and Proposal of Pharmacopeia Quality-Assessment Strategy Using TCM-Specific Library with UHPLC-Q-Exactive-Orbitrap-MS

Jieyu Anshen Granule is a traditional Chinese medicine prescription used for depression and primarily comprises five herbal medicines: Zhizi, Chaihu, Zhigancao, Danggui, and Yuanzhi. This study established a traditional Chinese herbal medicine-specific library using emerging ultra-high-performance liquid chromatography-quadrupole-orbitrap-tandem mass spectrometry analysis. Through library comparison, the study has fulfilled isomers distinction. As a result, 47 compounds were simultaneously and putatively identified from Jieyu Anshen Granule, including 12 unexpected compounds and 35 expected compounds. The unexpected compounds comprised cyclocommunol, 5-hydroxyflavone, tangeretin, 3,5,6,7,8,3',4'-heptemethoxyflavone, calycosin-7-O-β-D-glucoside, 7,4'-dihydroxyflavone, naringenin-7-O-β-D-glucoside, matrine, betaine, jervine, alantolactone, and hypericin. Among the 35 expected compounds, saikosaponin A, saikosaponin D, glycyrrhizic acid, geniposide, ligustilide, and polygalaxanthone III were further investigated using a quantum chemistry approach. Based on these, an effective quality assessment strategy is proposed for the Pharmacopeia, involving the simultaneous analysis of glycyrrhizic acid, geniposide, ligustilide, polygalaxanthone III, saikosaponins A and D through ultra-high-performance liquid chromatography-quadrupole-orbitrap-tandem mass spectrometry analysis. This strategy enables the detection of adulteration in relation to Zhizi, Chaihu, Zhigancao, Danggui, and Yuanzhi in Jieyu Anshen Granule. The findings of unexpected compounds will deepen the understanding of chemistry in Jieyu Anshen Granule.

Mining of antioxidant sesquiterpene lactones from the aerial parts of Saussurea involucrata with feature-based molecular network strategy

Sesquiterpene lactones (SLs) are a class of natural products with diverse structural scaffoldings and biological activities, making them intriguing objects in the fields of pharmaceutical industry, drug development, and pharmacology. Herein, fifteen SLs, including eleven undescribed SLs compounds sauruintones A-K (1-8 and 13-15), were isolated and identified from the aerial parts of Saussurea involucrata. Their structures were characterized by using mass spectrometry, spectroscopic methods, computational calculations, and single crystal X-ray diffraction. The Feature-Based Molecular Network (FBMN) strategy was utilized for the annotation of SLs with their MS/MS fragmentation patterns. Most of the SLs exerted their protective effects against oxidative stress by enhancing the levels of antioxidant enzyme (CAT) and reducing the malondialdehyde (MDA) levels. Among them, compound 12 exhibited potent reactive oxygen species (ROS) inhibitory activities and enhanced the activities of CAT, superoxide dismutase (SOD), and glutathione peroxidase (GSH), and decreased the content of MDA at concentrations of 10-25 μM. Further RT-qPCR assays and western blot analysis revealed it reduced the level of ROS by activating the nuclear factor erythroid 2-related factor 2 (Nrf-2) signaling pathway.

Puerarin Ameliorates Ferroptosis in Neuronal Injury Through the PI3K/AKT Signaling Pathway

Ferroptosis plays an important role in the pathogenesis of neuronal damage, generally mediated by iron and lipid peroxidation. In the present study, we measured the protective effects of puerarin against corticosterone-induced neuronal injury via PI3K/AKT-mediated activation of nuclear factor erythroid 2-related factor 2 (Nrf2). After exposing corticosterone-treated PC12 cells to indicated compounds, we measured the key regulators of ferroptosis (ferritin, SLC7A11, and Ptgs2), ferroptosis events (levels of iron, ROS, MDA, and GSH), and the PI3K/AKT/Nrf2 axis. Corticosterone induced ferroptosis in PC12 cells, evidenced by reduced levels of ferritin, SLC7A11, and GSH and increased levels of iron, ROS, and MDA. These effects were reversed by inhibiting ferroptosis with ferrostatin-1. Puerarin-mediated activation of Nrf2 repressed ferroptosis in corticosterone-treated PC12 cells by upregulating ferritin and SLC7A11 expression. Moreover, the protective effects of puerarin on ferroptosis in corticosterone-treated cells relied on the activation of the PI3K/AKT pathway though the upregulation of nuclear Nrf2. These findings indicate that ferroptosis plays an essential role in corticosterone-induced neuronal damage, and puerarin protects against ferroptosis in corticosterone-treated cells via PI3K/AKT-mediated activation of Nrf2.

CNS-peripheral immune interactions in hemorrhagic stroke

Stroke is a sudden and rapidly progressing ischemic or hemorrhagic cerebrovascular disease. When stroke damages the brain, the immune system becomes hyperactive, leading to systemic inflammatory response and immunomodulatory disorders, which could significantly impact brain damage, recovery, and prognosis of stroke. Emerging researches suggest that ischemic stroke-induced spleen contraction could activate a peripheral immune response, which may further aggravate brain injury. This review focuses on hemorrhagic strokes including intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) and discusses the central nervous system-peripheral immune interactions after hemorrhagic stroke induction. First, inflammatory progression after ICH and SAH is investigated. As a part of this review, we summarize the various kinds of inflammatory cell infiltration to aggravate brain injury after blood-brain barrier interruption induced by hemorrhagic stroke. Then, we explore hemorrhagic stroke-induced systemic inflammatory response syndrome (SIRS) and discuss the interactions of CNS and peripheral inflammatory response. In addition, potential targets related to inflammatory response for ICH and SAH are discussed in this review, which may lead to novel therapeutic strategies for hemorrhagic stroke.

Discovery of alantolactone as a naturally occurring NLRP3 inhibitor to alleviate NLRP3-driven inflammatory diseases in mice

BACKGROUND AND PURPOSE

The NLR family pyrin domain-containing 3 (NLRP3) inflammasome is activated in many inflammatory conditions. So far, no low MW compounds inhibiting NLRP3 have entered clinical use. Identification of naturally occurring NLRP3 inhibitors may be beneficial to the design and development of compounds targeting NLRP3. Alantolactone is a phytochemical from a traditional Chinese medicinal plant with anti-inflammatory activity, but its precise target remains unclear.

EXPERIMENTAL APPROACH

A bank of phytochemicals was screened for inhibitors of NLRP3-driven production of IL-1β in cultures of bone-marrow-derived macrophages from female C57BL/6 mice. Models of gouty arthritis and acute lung injury in male C57BL/6J mice were used to determine the in vivo effects of the most potent compound.

KEY RESULTS

Among the 150 compounds screened in vitro, alantolactone exhibited the highest inhibitory activity against LPS + ATP-induced production of IL-1β in macrophages, suppressing IL-1β secretion, caspase-1 activation and pyroptosis. Alantolactone directly bound to the NACHT domain of NLRP3 to inhibit activation and assembly of NLRP3 inflammasomes. Molecular simulation analysis suggested that Arg335 in NLRP3 was a critical residue for alantolactone binding, leading to suppression of NLRP3-NEK7 interaction. In vivo studies confirmed significant alleviation by alantolactone of two NLRP3-driven inflammatory conditions, acute lung injury and gouty arthritis.

CONCLUSION AND IMPLICATIONS

The phytochemical alantolactone inhibited activity of NLRP3 inflammasomes by directly targeting the NACHT domain of NLRP3. Alantolactone shows great potential in the treatment of NLRP3-driven diseases and could lead to the development of novel NLRP3 inhibitors.

Microglia and Post-Subarachnoid Hemorrhage Vasospasm: Review of Emerging Mechanisms and Treatment Modalities

Vasospasm is a potentially severe complication of subarachnoid hemorrhage. It can be attributed to neuroinflammation and the robust recruitment of microglia. Emerging evidence has linked this sustained inflammation to the development of delayed cerebral ischemia following subarachnoid hemorrhage. In this focused review, we provide an overview of the historical understanding of vasospasm. We then delve into the role of neuroinflammation and the activation of microglia. These activated microglia releases a host of inflammatory cytokines contributing to an influx of peripheral macrophages. This thereby opens a new and innovative treatment strategy to prevent vasospasm. Pre-clinical work has been promising, and the transition to clinical trials is warranted. Finally, some of the key mechanistic targets are outlined with emphasis on translation. This review will serve as a catalyst for researchers and clinicians alike in the quest to improve treatment options for vasospasm.