Inhibition of Heat Shock Protein 90 by 17-AAG Reduces Inflammation via P2X7 Receptor/NLRP3 Inflammasome Pathway and Increases Neurogenesis After Subarachnoid Hemorrhage in Mice

Therapeutic potential of stem cells in subarachnoid hemorrhage

Aneurysm rupture can result in subarachnoid hemorrhage, a condition with potentially severe consequences, such as disability and death. In the acute stage, early brain injury manifests as intracranial pressure elevation, global cerebral ischemia, acute hydrocephalus, and direct blood-brain contact due to aneurysm rupture. This may subsequently cause delayed cerebral infarction, often with cerebral vasospasm, significantly affecting patient outcomes. Chronic complications such as brain volume loss and chronic hydrocephalus can further impact outcomes. Investigating the mechanisms of subarachnoid hemorrhage-induced brain injury is paramount for identifying effective treatments. Stem cell therapy, with its multipotent differentiation capacity and anti-inflammatory effects, has emerged as a promising approach for treating previously deemed incurable conditions. This review focuses on the potential application of stem cells in subarachnoid hemorrhage pathology and explores their role in neurogenesis and as a therapeutic intervention in preclinical and clinical subarachnoid hemorrhage studies.

Novel insights into neuroinflammatory mechanisms in traumatic brain injury: Focus on pattern recognition receptors as therapeutic targets

Traumatic brain injury (TBI) is a major global health concern and a leading cause of morbidity and mortality. Neuroinflammation is a pivotal driver of both the acute and chronic phases of TBI, with pattern recognition receptors (PRRs) playing a central role in detecting damage-associated molecular patterns (DAMPs) and initiating immune responses. Key PRR subclasses, including Toll-like receptors (TLRs), NOD-like receptors (NLRs), and cGAS-like receptors (cGLRs), are abundantly expressed in central nervous system (CNS) cells and infiltrating immune cells, where they mediate immune activation, amplify neuroinflammatory cascades, and exacerbate secondary injury mechanisms. This review provides a comprehensive analysis of these PRR subclasses, detailing their distinct structural characteristics, expression patterns, and roles in post-TBI immune responses. We critically examine the molecular mechanisms underlying PRR-mediated signaling and explore their contributions to neuroinflammatory pathways and secondary injury processes. Additionally, preclinical and clinical evidence supporting the therapeutic potential of targeting PRRs to mitigate neuroinflammation and improve neurological outcomes is discussed. By integrating recent advancements, this review offers an in-depth understanding of the role of PRRs in TBI pathobiology and underscores the potential of PRR-targeted therapies in mitigating TBI-associated neurological deficits.

The Inflammasome: A Promising Potential Therapeutic Target for Early Brain Injury Following Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH), a severe cerebrovascular disorder, is principally instigated by the rupture of an aneurysm. Early brain injury (EBI), which gives rise to neuronal demise, microcirculation impairments, disruption of the blood-brain barrier, cerebral edema, and the activation of oxidative cascades, has been established as the predominant cause of mortality among patients with SAH. These pathophysiological processes hinge on the activation of inflammasomes, specifically the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)and absent in melanoma 2 (AIM2) inflammasomes. These inflammasomes assume a crucial role in downstream intracellular signaling pathways and hold particular significance within the nervous system. The activation of inflammasomes can be modulated, either by independently regulating these two entities or by influencing their engagement at specific target loci within the pathway, thereby attenuating EBI subsequent to SAH. Although certain clinical instances lend credence to this perspective, more in-depth investigations are essential to ascertain the optimal treatment regimen, encompassing dosage, timing, administration route, and frequency. Consequently, targeting the ensuing early brain injury following SAH represents a potentially efficacious therapeutic approach.

PGAM5 promotes RIPK1-PANoptosome activity by phosphorylating and activating RIPK1 to mediate PANoptosis after subarachnoid hemorrhage in rats

Neuronal death plays a crucial role in early brain injury after subarachnoid hemorrhage (SAH). PANoptosis is a programmed form of cell death regulated by the PANoptosome, which possesses key characteristics of pyroptosis, apoptosis and necroptosis. Phosphoglycerate mutase family member 5 (PGAM5) has specific phosphatase activity that phosphorylates or dephosphorylates serine and threonine residues on bound proteins such as receptor-interacting protein kinase 1 (RIPK1), which are involved in programmed cell death. This study aimed to explore whether PANoptosis occurs after subarachnoid hemorrhage and to investigate the role of PGAM5 in early brain injury after SAH. A monofilament perforation SAH model in Sprague-Dawley rats was established, and PGAM5 siRNA (siPGAM5) was administered via intracerebroventricular injection 48 h before SAH modeling. The efficacy of siPGAM5 treatment was assessed via neurological scoring, and the impact of siPGAM5 on PANoptosis was evaluated via Western blotting, TUNEL staining and ELISA. To investigate its potential mechanism, the RIPK1 activator birinapant was administered intraperitoneally 0.5 h after SAH. The role of RIPK in PGAM5-mediated PANoptosis was evaluated by Western blotting and coimmunoprecipitation. Our findings indicate that PANoptosis occurs in neurons after SAH and that reducing PGAM5 in the cytosol after SAH can reduce PANoptosis and enhance the short-term and long-term neurological functions of SAH rats. Mechanistically, we discovered that PGAM5 can directly bind to and phosphorylate and activate RIPK1 (ser 166), triggering the assembly of the RIPK1-PANoptosome complex. In conclusion, our study revealed that the increased PGAM5 in the mitochondria-free cytosol after SAH can bind to and activate RIPK1 (ser 166), driving the assembly of the RIPK1-PANoptosome and mediating PANoptosis after SAH. PGAM5 and PANoptosis might be novel therapeutic targets for SAH.

Retinal Pigment Epithelium Under Oxidative Stress: Chaperoning Autophagy and Beyond

The structural and functional integrity of the retinal pigment epithelium (RPE) plays a key role in the normal functioning of the visual system. RPE cells are characterized by an efficient system of photoreceptor outer segment phagocytosis, high metabolic activity, and risk of oxidative damage. RPE dysfunction is a common pathological feature in various retinal diseases. Dysregulation of RPE cell proteostasis and redox homeostasis is accompanied by increased reactive oxygen species generation during the impairment of phagocytosis, lysosomal and mitochondrial failure, and an accumulation of waste lipidic and protein aggregates. They are the inducers of RPE dysfunction and can trigger specific pathways of cell death. Autophagy serves as important mechanism in the endogenous defense system, controlling RPE homeostasis and survival under normal conditions and cellular responses under stress conditions through the degradation of intracellular components. Impairment of the autophagy process itself can result in cell death. In this review, we summarize the classical types of oxidative stress-induced autophagy in the RPE with an emphasis on autophagy mediated by molecular chaperones. Heat shock proteins, which represent hubs connecting the life supporting pathways of RPE cells, play a special role in these mechanisms. Regulation of oxidative stress-counteracting autophagy is an essential strategy for protecting the RPE against pathological damage when preventing retinal degenerative disease progression.

Activation of Piezo1 by intracranial hypertension induced neuronal apoptosis via activating hippo pathway

AIM

Most of the subarachnoid hemorrhage (SAH) patients experienced the symptom of severe headache caused by intracranial hypertension. Piezo1 is a mechanosensitive ion channel protein. This study aimed to investigate the effect of Piezo1 on neurons in response to intracranial hypertension.

METHODS

The SAH rat model was performed by the modified endovascular perforation method. Piezo1 inhibitor GsMTx4 was administered intraperitoneally after SAH induction. To investigate the underlying mechanism, the selective Piezo1 agonist Yoda1, Piezo1 shRNA, and MY-875 were administered via intracerebroventricular injection before SAH induction. In vitro, we designed a pressurizing device to exclusively explore the effect of Piezo1 activation on primary neurons. Neurons were pretreated with Piezo1 inhibition followed by intracranial hypertension treatment, and then apoptosis-related proteins were detected.

RESULTS

Piezo1 inhibition significantly attenuated neuronal apoptosis and improved the outcome of neurological deficits in rats after SAH. The Hippo pathway agonist MY-875 reversed the anti-apoptotic effects of Piezo1 knockdown. In vitro, intracranial hypertension mimicked by the pressurizing device induced Piezo1 expression, resulting in Hippo pathway activation and neuronal apoptosis. The Hippo pathway inhibitor Xmu-mp-1 attenuated Yoda1-induced neuronal apoptosis. In addition, the combination of hypertension and oxyhemoglobin treatment exacerbated neuronal apoptosis.

CONCLUSIONS

Intracranial hypertension induced Piezo1 expression, neuronal apoptosis, and the Hippo pathway activation; the Hippo signaling pathway is involved in Piezo1 activation-induced neuronal apoptosis in respond to intracranial hypertension. Primary neurons treated with intracranial hypertension and oxyhemoglobin together can better characterize the circumstance of SAH in vivo, which is contributed to construct an ideal in vitro SAH model.

MFGE8 promotes adult hippocampal neurogenesis in rats following experimental subarachnoid hemorrhage via modifying the integrin β3/Akt signaling pathway

Subarachnoid hemorrhage (SAH) is one of the most severe type of cerebral strokes, which can cause multiple cellular changes in the brain leading to neuronal injury and neurological deficits. Specifically, SAH can impair adult neurogenesis in the hippocampal dentate gyrus, thus may affecting poststroke neurological and cognitive recovery. Here, we identified a non-canonical role of milk fat globule epidermal growth factor 8 (MFGE8) in rat brain after experimental SAH, involving a stimulation on adult hippocampal neurogenesis(AHN). Experimental SAH was induced in Sprague-Dawley rats via endovascular perforation, with the in vivo effect of MFGE8 evaluated via the application of recombinant human MFGE8 (rhMFGE8) along with pharmacological interventions, as determined by hemorrhagic grading, neurobehavioral test, and histological and biochemical analyses of neurogenesis related markers. Results: Levels of the endogenous hippocampal MFGE8 protein, integrin-β3 and protein kinase B (p-Akt) were elevated in the SAH relative to control groups, while that of hippocalcin (HPCA) and cyclin D1 showed the opposite change. Intraventricular rhMGFE8 infusion reversed the decrease in doublecortin (DCX) immature neurons in the DG after SAH, along with improved the short/long term neurobehavioral scores. rhMGFE8 treatment elevated the levels of phosphatidylinositol 3-kinase (PI3K), p-Akt, mammalian target of rapamycin (mTOR), CyclinD1, HPCA and DCX in hippocampal lysates, but not that of integrin β3 and Akt, at 24 hr after SAH. Treatment of integrin β3 siRNA, the PI3K selective inhibitor ly294002 or Akt selective inhibitor MK2206 abolished the effects of rhMGFE8 after SAH. In conclusion, MFGE8 is upregulated in the hippocampus in adult rats with reduced granule cell genesis. rhMFGE8 administration can rescue this impaired adult neurogenesis and improve neurobehavioral recovery. Mechanistically, the effect of MFGE8 on hippocampal adult neurogenesis is mediated by the activation of integrin β3/Akt pathway. These findings suggest that exogenous MFGE8 may be of potential therapeutic value in SAH management. Graphical abstract and proposed pathway of rhMFGE8 administration attenuate hippocampal injury by improving neurogenesis in SAH models. SAH caused hippocampal injury and neurogenesis interruption. Administered exogenous MFGE8, recombinant human MFGE8(rhMFGE8), could ameliorate hippocampal injury and improve neurological functions after SAH. Mechanistically, MFGE8 bind to the receptor integrin β3, which activated the PI3K/Akt pathway to increase the mTOR expression, and further promote the expression of cyclin D1, HPCA and DCX. rhMFGE8 could attenuated hippocampal injury by improving neurogenesis after SAH, however, know down integrin β3 or pharmacological inhibited PI3K/Akt by ly294002 or MK2206 reversed the neuro-protective effect of rhMFGE8.

Anti-inflammatory activities of novel heat shock protein 90 isoform selective inhibitors in BV-2 microglial cells

Heat shock protein 90 (Hsp90) is a family of chaperone proteins that consists of four isoforms: Hsp90α, Hsp90β, glucose-regulated protein 94 (Grp94), and tumor necrosis factor type 1 receptor-associated protein (TRAP1). They are involved in modulating the folding, maturation, and activation of their client proteins to regulate numerous intracellular signaling pathways. Previous studies demonstrated that pan-Hsp90 inhibitors reduce inflammatory signaling pathways resulting in a reduction of inflammation and pain but show toxicities in cancer-related clinical trials. Further, the role of Hsp90 isoforms in inflammation remains poorly understood. This study aimed to determine anti-inflammatory activities of Hsp90 isoforms selective inhibitors on the lipopolysaccharide (LPS)-induced inflammation in BV-2 cells, a murine microglial cell line. The production of inflammatory mediators such as nitric oxide (NO), interleukin 1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α) was measured. We also investigated the impact of Hsp90 isoform inhibitors on the activation of nuclear factor kappa B (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), and mitogen-activated protein kinases (MAPKs). We found that selective inhibitors of Hsp90β reduced the LPS-induced production of NO, IL-1β, and TNF-α via diminishing the activation of NF-κB and Extracellular signal-regulated kinases (ERK) MAPK. The Hsp90α, Grp94, TRAP1 inhibitors had limited effect on the production of inflammatory mediators. These findings suggest that Hsp90β is the key player in LPS-induced neuroinflammation. Thereby providing a more selective drug target for development of medications involved in pain management that can potentially contribute to the reduction of adverse side effects associated with Hsp90 pan inhibitors.

HSP90, a Common Therapeutic Target for Suppressing Skin Injury Caused by Exposure to Chemically Diverse Classes of Blistering Agents

Vesicants such as arsenicals and mustards produce highly painful cutaneous inflammatory and blistering responses, hence developed as chemical weapons during World War I/II. Here, using lewisite and sulfur mustard surrogates, namely phenylarsine oxide (PAO) and 2-chloroethyl ethyl sulfide (CEES), respectively, we defined a common underlying mechanism of toxic action by these two distinct classes of vesicants. Murine skin exposure to these chemicals causes tissue destruction characterized by increase in skin bifold thickness, Draize score, infiltration of inflammatory cells, and apoptosis of epidermal and dermal cells. RNA sequencing analysis identified ∼346 inflammatory genes that were commonly altered by both PAO and CEES, along with the identification of cytokine signaling activation as the top canonical pathway. Activation of several proinflammatory genes and pathways is associated with phosphorylation-dependent activation of heat shock protein 90α (p-HSP90α). Topical treatment with known HSP90 inhibitors SNX-5422 and IPI-504 post PAO or CEES skin challenge significantly attenuated skin damage including reduction in overall skin injury and clinical scores. In addition, highly upregulated inflammatory genes Saa3, Cxcl1, Ccl7, IL-6, Nlrp3, Csf3, Chil3, etc. by both PAO and CEES were significantly diminished by treatment with HSP90 inhibitors. These drugs not only reduced PAO- or CEES-induced p-HSP90α expression but also its client proteins NLRP3 and pP38 and the expression of their target inflammatory genes. Our data confirm a critical role of HSP90 as a shared underlying molecular target of toxicity by these two distinct vesicants and provide an effective and novel medical countermeasure to suppress vesicant-induced skin injury. SIGNIFICANCE STATEMENT: Development of effective and novel mechanism-based antidotes that can simultaneously block cutaneous toxic manifestations of distinct vesicants is important and urgently needed. Due to difficulties in determining the exact nature of onsite chemical exposure, a potent drug that can suppress widespread cutaneous damage may find great utility. Thus, this study identified HSP90 as a common molecular regulator of cutaneous inflammation and injury by two distinct warfare vesicants, arsenicals and mustards, and HSP90 inhibitors afford significant protection against skin damage.

Purinergic P2X7 receptor as a potential therapeutic target in depression

The elaborate mechanisms of depression have always been a research hotspot in recent years, and the pace of research has never ceased. The P2X7 receptor (P2X7R) belongs to one of the adenosine triphosphates (ATP)-gated cation channels that exist widely in brain tissues and play a prominent role in the regulation of depression-related pathology. To date, the role of purinergic P2X7R in the mechanisms underlying depression is not fully understood. In this review, we conclude that the purinergic receptor P2X7 is a potential therapeutic target for depression based on research results published over the past 5 years in Google Scholar and the National Library of Medicine (PubMed). Additionally, we introduced the functional characteristics of P2X7R and confirmed that excessive activation of P2X7R led to increased release of inflammatory cytokines, which eventually contributed to depression. Furthermore, the inhibition of P2X7R produced antidepressant-like effects in animal models of depression, further proving that P2X7R signalling mediates depression-like behaviours. Finally, we summarised related studies on drugs that exert antidepressant effects by regulating the expression of P2X7R. We hope that the conclusions of this review will provide information on the role of P2X7R in the neuropathophysiology of depression and novel therapeutic targets for the treatment of depression.

P2X7 receptor antagonist A-438079 alleviates oxidative stress of lung in LPS-induced septic rats

Sepsis is a deadly systemic inflammatory response of the body against infection resulting in immune response, cell differentiation and organ damage. Endotoxemia is one of the causes of sepsis-related acute respiratory distress and respiratory burst is an important generator of oxidants. Inflammation may be aggravated by overexpression of ATP-gated purinergic receptors (i.e., P2X7R) following cell damage. We aimed to evaluate the effects of P2X7R antagonist A-438079 on lung oxidative status and the receptor expression in endotoxemia of sepsis. Rats were subjected to sepsis by E. coli lipopolysaccharide (LPS) and treated with 15 mg/kg A-438079. The increase in circulatory IL-1β and IL-8 concentrations in LPS group confirmed the systemic inflammatory response to endotoxemia compared with Control groups (p < 0.001). Besides, there was an increase in P2X7R expression in lung tissue after LPS administration. Compared with Control groups, there were significant increases in the values of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) (p < 0.001), and myeloperoxidase (MPO) (p < 0.05) in lung tissue of LPS group. P2X7R expression in lung and IL-1β level in blood did not increase in LPS + A-438079 group. A-438079 decreased the lung levels of MDA, GSH, CAT and SOD (p < 0.001), and MPO (p < 0.01) in septic rats. As a result, administration of pathogen-associated LPS led to increased P2X7R expression into lung tissue and elevated lipid peroxidation product MDA with regard to oxidative damage. The P2X7R antagonist A-438079 alleviated the oxidative stress of lung with a balance of tissue oxidant/antioxidant factors in experimental sepsis in rats.

The Potential of NLRP3 Inflammasome as a Therapeutic Target in Neurological Diseases

NLRP3 (NLRP3: NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome is the best-described inflammasome that plays a crucial role in the innate immune system and a wide range of diseases. The intimate association of NLRP3 with neurological disorders, including neurodegenerative diseases and strokes, further emphasizes its prominence as a clinical target for pharmacological intervention. However, after decades of exploration, the mechanism of NLRP3 activation remains indefinite. This review highlights recent advances and gaps in our insights into the regulation of NLRP3 inflammasome. Furthermore, we present several emerging pharmacological approaches of clinical translational potential targeting the NLRP3 inflammasome in neurological diseases. More importantly, despite small-molecule inhibitors of the NLRP3 inflammasome, we have focused explicitly on Chinese herbal medicine and botanical ingredients, which may be splendid therapeutics by inhibiting NLRP3 inflammasome for central nervous system disorders. We expect that we can contribute new perspectives to the treatment of neurological diseases.

The NLRP3 inflammasome: role in the pathobiology of chronic pain

Chronic pain is not only one of the most common health problems, it is often challenging to treat adequately. Chronic pain has a high prevalence globally, affecting approximately 20% of the adult population. Chronic inflammatory pain and neuropathic (nerve) pain conditions are areas of large unmet medical need because analgesic/adjuvant agents recommended for alleviation of these types of chronic pain often lack efficacy and/or they produce dose-limiting side effects. Recent work has implicated the NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome in the pathobiology of chronic pain, especially neuropathic and inflammatory pain conditions. NLRP3 is activated by damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs). This in turn leads to recruitment and activation of caspase-1 an enzyme that cleaves the inactive IL-1β and IL-18 precursors to their respective mature pro-inflammatory cytokines (IL-1β and IL-18) for release into the cellular milieu. Caspase-1 also cleaves the pyroptosis-inducing factor, gasdermin D, that leads to oligomerization of its N-terminal fragment to form pores in the host cell membrane. This then results in cellular swelling, lysis and release of cytoplasmic contents in an inflammatory form of cell death, termed pyroptosis. The ultimate outcome may lead to the development of neuropathic pain and/or chronic inflammatory pain. In this review, we address a role for NLRP3 inflammasome activation in the pathogenesis of various chronic pain conditions.

The ferroptosis signature predicts the prognosis and immune microenvironment of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a cancer with a high metastatic rate and poor prognosis. Growing studies suggest that ferroptosis take part in the development of tumours. At the same time, the connection between ferroptosis-related genes (FRGs) and the prognosis of NPC remains unclear. In this study, we explored the dysregulated FRGs between normal control and tumour samples of NPC. Firstly, 14 of 36 differentially expressed FRGs were identified in NPC tissues compared to normal tissues, among which ABCC1, GLS2, CS and HMGCR were associated with poor prognosis for patients. The four ferroptosis genes were used for consensus cluster analysis and two risk-related FRGs (ABCC1 and GLS2) were used in a risk model. The ROC curve revealed the good predictive performance of this risk signature. Multivariate analysis revealed that risk score and intratumoral TILs were independent risk factors linked to prognosis. Additionally, our results suggested that the risk signature was attached to the immune microenvironment. Moreover, the NPC patients with high risk were sensitive to chemotherapeutic drugs including axitinib, docetaxel, embelin, epothilone.B, parthenolide, thapsigargin, tipifarnib, vinorelbine. Finally, the expression of ABCC1 and GLS2 was validated in NPC tissues using immunohistochemistry. Together, these results revealed ferroptosis may be a potential biomarker in NPC and representing a promising future direction in prognosis and therapeutic strategy for the treatment of NPC.

The NLRP3 inflammasome is involved in resident intruder paradigm-induced aggressive behaviors in mice

Background: Aggressive behaviors are one of the most important negative behaviors that seriously endangers human health. Also, the central para-inflammation of microglia triggered by stress can affect neurological function, plasticity, and behavior. NLRP3 integrates stress-related signals and is a key driver of this neural para-inflammation. However, it is unclear whether the NLRP3 inflammasome is implicated in the development of aggressive behaviors. Methods: First, aggressive behavior model mice were established using the resident intruder paradigm. Then, aggressive behaviors were determined with open-field tests (OFT), elevated plus-maze (EPM), and aggressive behavior tests (AT). Moreover, the expression of P2X7R and NLRP3 inflammasome complexes were assessed by immunofluorescence and Western blot. The levels of NLRP3 and inflammatory cytokines were evaluated using enzyme-linked immunosorbent assay (ELISA) kits. Finally, nerve plasticity damage was observed by immunofluorescence, transmission electron microscope, and BrdU staining. Results: Overall, the resident intruder paradigm induced aggressive behaviors, activated the hippocampal P2X7R and NLRP3 inflammasome, and promoted the release of proinflammatory cytokines IL-1β in mice. Moreover, NLRP3 knockdown, administration of P2X7R antagonist (A804598), and IL-1β blocker (IL-1Ra) prevented NLRP3 inflammasome-driven inflammatory responses and ameliorated resident intruder paradigm-induced aggressive behaviors. Also, the resident intruder paradigm promoted the activation of mouse microglia, damaging synapses in the hippocampus, and suppressing hippocampal regeneration in mice. Besides, NLRP3 knockdown, administration of A804598, and IL-1Ra inhibited the activation of microglia, improved synaptic damage, and restored hippocampal regeneration. Conclusion: The NLRP3 inflammasome-driven inflammatory response contributed to resident intruder paradigm-induced aggressive behavior, which might be related to neuroplasticity. Therefore, the NLRP3 inflammasome can be a potential target to treat aggressive behavior-related mental illnesses.

NLRP3 Inflammasome Overactivation in Patients with Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is an uncommon and severe subtype of stroke leading to the loss of many years of productive life. We analyzed NLRP3 activity as well as key components of the inflammasome cascade in monocytes and plasma from 28 patients with aSAH and 14 normal controls using flow cytometry, western blot, ELISA, and qPCR technologies. Our data reveal that monocytes from patients with aSAH present an overactivation of the NLRP3 inflammasome, which results in the presence of high plasma levels of interleukin (IL)-1β, IL-18, gasdermin D, and tissue factor. Although further research is needed, we propose that serum tissue factor concentration might be a useful prognosis biomarker for clinical outcome, and for Tako-Tsubo cardiomyopathy and cerebral vasospasm prediction. Remarkably, MCC-950 inhibitor effectively blocks NLRP3 activation in aSAH monocyte culture and supresses tissue factor release to the extracellular space. Finally, our findings suggest that NLRP3 activation could be due to the release of erythrocyte breakdown products to the subarachnoid space during aSAH event. These data define NLRP3 activation in monocytes from aSAH patients, indicating systemic inflammation that results in serum TF upregulation which in turns correlates with aSAH severity and might serve as a prognosis biomarker for aSAH clinical outcome and for cerebral vasospasm and Tako-Tsubo cardiomyopathy prediction.

Neuroprotection by Trans-Resveratrol in Rats With Intracerebral Hemorrhage: Insights into the Role of Adenosine A1 Receptors

Given the neuroprotective effects of trans-resveratrol (RV), this study aimed to investigate the involvement of the adenosine A1 receptor (A1R) in RV-mediated neuroprotection in a rat intracerebral hemorrhage (ICH) model induced by intrastriatal injection of collagenase. Rats were divided into 5 groups: (1) control, (2) sham-operated, (3) ICH pretreated with vehicle, (4) ICH pretreated with RV, and (5) ICH pretreated with RV and the A1R antagonist DPCPX. At 48 hours after ICH, the rats were subjected to neurological testing. Brain tissues were assessed for neuronal density and morphological features using routine and immunohistochemical staining. Expression of tumor necrosis factor-α (TNF-α), caspase-3, and RIPK3 proteins was examined using ELISA. A1R, MAPK P38, Hsp90, TrkB, and BDNF genes were examined using RT-qPCR. RV protected against neurological deficits and neuronal depletion, restored the expression of TNF-α, CASP3, RIPK3, A1R, and Hsp90, and increased BDNF/TrkB. DPCPX abolished the effects of RV on neurological outcomes, neuronal density, CASP3, RIPK3, A1R, Hsp90, and BDNF. These data indicate that the neuroprotection by RV involves A1R and inhibits CASP3-dependent apoptosis and RIPK3-dependent necroptosis in the perihematoma region; this is likely to be mediated by crosstalk between A1R and the BDNF/TrkB pathway.

The Inflammasome NLR Family Pyrin Domain-Containing Protein 3 (NLRP3) as a Novel Therapeutic Target for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a dramatic disease without cure. The US Food and Drug Administration-approved drugs, pirfenidone and nintedanib, only slow disease progression. The clinical investigation of novel therapeutic approaches for IPF is an unmet clinical need. Nucleotide-binding oligomerization domain-like receptor or NOD-like receptors are pattern recognition receptors capable of binding a large variety of stress factors. NLR family pyrin domain-containing protein 3 (NLRP3), once activated, promotes IL-1β, IL-18 production, and innate immune responses. Multiple reports indicate that the inflammasome NLRP3 is overactivated in IPF patients, leading to increased production of class I IL and collagens. Similarly, data from animal models of pulmonary fibrosis confirm the role of NLRP3 in the development of chronic lung injury and pulmonary fibrosis. This report provides a review of the evidence of NLRP3 activation in IPF and of NLRP3 inhibition in different animal models of fibrosis, and highlights the recent advances in direct and indirect NLRP3 inhibitors.

Knock-Down of CD24 in Astrocytes Aggravates Oxyhemoglobin-Induced Hippocampal Neuron Impairment

Subarachnoid hemorrhage (SAH), as one of the most severe hemorrhagic strokes, is closely related to neuronal damage. Neurogenesis is a promising therapy, however, reliable targets are currently lacking. Increasing evidence has indicated that CD24 is associated with the growth of hippocampal neurons and the regulation of neural stem/precursor cell proliferation. To investigate the potential effect of CD24 in astrocytes on neuron growth in the hippocampus, we used a Transwell co-culture system of hippocampal astrocytes and neurons, and oxyhemoglobin (OxyHb) was added to the culture medium to mimic SAH in vitro. A specific lentivirus was used to knock down CD24 expression in astrocytes, which was verified by western blot, quantitative real-time polymerase chain reaction, and immunofluorescent staining. Astrocyte activation, neurite elongation, neuronal apoptosis, and cell viability were also assessed. We first determined the augmented expression level of CD24 in hippocampal astrocytes after SAH. A similar result was observed in cultured astrocytes exposed to OxyHb, and a corresponding change in SHP2/ERK was also noticed. CD24 in astrocytes was then downregulated by the lentivirus, which led to the impairment of axons and dendrites on the co-cultured neurons. Aggravated neuronal apoptosis was induced by the CD24 downregulation in astrocytes, which might be a result of a lower level of brain derived neurotrophic factor (BDNF). In conclusion, the knock-down of CD24 in astrocytes suppressed hippocampal neuron growth, in which the SHP2-ERK signaling pathway and BNDF were possibly involved.

Hypoxia Tolerant Species: The Wisdom of Nature Translated into Targets for Stroke Therapy

Human neurons rapidly die after ischemia and current therapies for stroke management are limited to restoration of blood flow to prevent further brain damage. Thrombolytics and mechanical thrombectomy are the available reperfusion treatments, but most of the patients remain untreated. Neuroprotective therapies focused on treating the pathogenic cascade of the disease have widely failed. However, many animal species demonstrate that neurons can survive the lack of oxygen for extended periods of time. Here, we reviewed the physiological and molecular pathways inherent to tolerant species that have been described to contribute to hypoxia tolerance. Among them, Foxo3 and Eif5A were reported to mediate anoxic survival in Drosophila and Caenorhabditis elegans, respectively, and those results were confirmed in experimental models of stroke. In humans however, the multiple mechanisms involved in brain cell death after a stroke causes translation difficulties to arise making necessary a timely and coordinated control of the pathological changes. We propose here that, if we were able to plagiarize such natural hypoxia tolerance through drugs combined in a pharmacological cocktail it would open new therapeutic opportunities for stroke and likely, for other hypoxic conditions.

Atorvastatin ameliorates early brain injury after subarachnoid hemorrhage via inhibition of pyroptosis and neuroinflammation

Subarachnoid hemorrhage (SAH) is a subtype of stroke with high mortality and morbidity due to the lack of effective therapy. Atorvastatin has been reported to alleviate early brain injury (EBI) following subarachnoid hemorrhage (SAH) via reducing reactive oxygen species, antiapoptosis, regulated autophagy, and neuroinflammation. Which was the related to the pyroptosis? Pyroptosis can be defined as a highly specific inflammatory programmed cell death, distinct from classical apoptosis and necrosis. However, the precise role of pyroptosis in atorvastatin-mediated neuroprotection following SAH has not been confirmed. The present study aimed to investigate the neuroprotection and potential molecular mechanisms of atorvastatin in the SAH-induced EBI via regulating neural pyroptosis using the filament perforation model of SAH in male C57BL/6 mice, and the hemin-induced neuron damage model in HT-22. Atorvastatin or vehicle was administrated 2 h after SAH and hemin-induced neuron damage. The mortality, neurological score, brain water content, and neuronal death were evaluated. The results show that the atorvastatin treatment markedly increased survival rate, neurological score, greater survival of neurons, downregulated the protein expression of NLRP1, cleaved caspase-1, interleukin-1β (IL-1β), and IL-18, which indicated that atorvastatin-inhibited pyroptosis and neuroinflammation, ameliorated neuron death in vivo/vitro subjected to SAH. Taken together, this study demonstrates that atorvastatin improved the neurological outcome in rats and reduced the neuron death by against neural pyroptosis and neuroinflammation.

Differential Expression of Inflammasome-Related Genes in Induced Pluripotent Stem-Cell-Derived Retinal Pigment Epithelial Cells with or without History of Age-Related Macular Degeneration

Inflammation is a key underlying factor of age-related macular degeneration (AMD) and inflammasome activation has been linked to disease development. Induced pluripotent stem-cell-derived retinal pigment epithelial cells (iPSC-RPE) are an attractive novel model system that can help to further elucidate disease pathways of this complex disease. Here, we analyzed the effect of dysfunctional protein clearance on inflammation and inflammasome activation in iPSC-RPE cells generated from a patient suffering from age-related macular degeneration (AMD) and an age-matched control. We primed iPSC-RPE cells with IL-1α and then inhibited both proteasomal degradation and autophagic clearance using MG-132 and bafilomycin A1, respectively, causing inflammasome activation. Subsequently, we determined cell viability, analyzed the expression levels of inflammasome-related genes using a PCR array, and measured the levels of pro-inflammatory cytokines IL-1β, IL-6, IL-8, and MCP-1 secreted into the medium. Cell treatments modified the expression of 48 inflammasome-related genes and increased the secretion of mature IL-1β, while reducing the levels of IL-6 and MCP-1. Interestingly, iPSC-RPE from an AMD donor secreted more IL-1β and expressed more Hsp90 prior to the inhibition of protein clearance, while MCP-1 and IL-6 were reduced at both protein and mRNA levels. Overall, our results suggest that cellular clearance mechanisms might already be dysfunctional, and the inflammasome activated, in cells with a disease origin.

The Potential Role of Inflammation in Modulating Endogenous Hippocampal Neurogenesis After Spinal Cord Injury

Currently there are approximately 291,000 people suffering from a spinal cord injury (SCI) in the United States. SCI is associated with traumatic changes in mobility and neuralgia, as well as many other long-term chronic health complications, including metabolic disorders, diabetes mellitus, non-alcoholic steatohepatitis, osteoporosis, and elevated inflammatory markers. Due to medical advances, patients with SCI survive much longer than previously. This increase in life expectancy exposes them to novel neurological complications such as memory loss, cognitive decline, depression, and Alzheimer's disease. In fact, these usually age-associated disorders are more prevalent in people living with SCI. A common factor of these disorders is the reduction in hippocampal neurogenesis. Inflammation, which is elevated after SCI, plays a major role in modulating hippocampal neurogenesis. While there is no clear consensus on the mechanism of the decline in hippocampal neurogenesis and cognition after SCI, we will examine in this review how SCI-induced inflammation could modulate hippocampal neurogenesis and provoke age-associated neurological disorders. Thereafter, we will discuss possible therapeutic options which may mitigate the influence of SCI associated complications on hippocampal neurogenesis.

Safinamide prevents lipopolysaccharide (LPS)-induced inflammation in macrophages by suppressing TLR4/NF-κB signaling

Inflammation is a basal host defense response that eliminates the causes and consequences of infection and tissue injury. Macrophages are the primary immune cells involved in the inflammatory response. When activated by LPS, macrophages release various pro-inflammatory cytokines, chemokines, inflammatory mediators, and MMPs. However, unbridled inflammation causes further damage to tissues. Safinamide is a selective and reversible monoamine oxidase B (MAOB) inhibitor that has been used for the treatment of Parkinson's disease. In this study, we aimed to investigate whether safinamide has effects on LPS-treated macrophages. Our results show that safinamide inhibited the expression of pro-inflammatory cytokines such as IL-1α, TNF-α, and IL-6. Furthermore, safinamide suppressed the production of CXCL1 and CCL2, thereby preventing leukocyte migration. In addition, safinamide reduced iNOS-derived NO, COX-2-derived PGE₂, MMP-2, and MMP-9. Importantly, the functions of safinamide mentioned above were found to be dependent on its inhibitory effect on the TLR4/NF-κB signaling pathway. Our data indicates that safinamide may exert a protective effect against inflammatory response.

MFGE8 mitigates brain injury in a rat model of SAH by maintaining vascular endothelial integrity via TIGβ5/PI3K/CXCL12 signaling

Leaked blood components, injured endothelial cells, local inflammatory response and vasospasm may converge to promote microthrombosis following subarachnoid hemorrhage (SAH). Previously, we showed that the milk fat globule-epidermal growth factor 8 (MFGE8) can mitigate SAH-induced microthrombosis. This present study was aimed to explore the molecular pathway participated in MFGE8-dependent protection on vascular endothelium. Immunofluorescence, immunoblot and behavioral tests were used to determine the molecular partner and signaling pathway mediating the effect of MFGE8 in vascular endothelium in rats with experimental SAH and controls, together with the applications of RNA silencing and pharmacological intervention methods. Relative to control, recombinant human MFGE8 (rhMFGE8) treatment increased 5-bromo-2'-deoxyuridine (BrdU) labeled new endothelial cells, reduced TUNUL-positive endothelial cells and elevated the expression of phosphatidylinositol 3-kinase (PI3K) and chemokine (C-X-C motif) ligand 12 (CXCL12), in the brains of SAH rats. These effects were reversed by MFGE8 RNA silencing, as well as following cilengitide and wortmannin intervention. These results suggest that MFGE8 promotes endothelial regeneration and mitigates endothelial DNA damage through the activation of the TIGβ5/PI3K/CXCL12 signaling pathway.

TAS-116, a Well-Tolerated Hsp90 Inhibitor, Prevents the Activation of the NLRP3 Inflammasome in Human Retinal Pigment Epithelial Cells

Chronic inflammation has been associated with several chronic diseases, such as age-related macular degeneration (AMD). The NLRP3 inflammasome is a central proinflammatory signaling complex that triggers caspase-1 activation leading to the maturation of IL-1β. We have previously shown that the inhibition of the chaperone protein, Hsp90, prevents NLRP3 activation in human retinal pigment epithelial (RPE) cells; these are cells which play a central role in the pathogenesis of AMD. In that study, we used a well-known Hsp90 inhibitor geldanamycin, but it cannot be used as a therapy due to its adverse effects, including ocular toxicity. Here, we have tested the effects of a novel Hsp90 inhibitor, TAS-116, on NLRP3 activation using geldanamycin as a reference compound. Using our existing protocol, inflammasome activation was induced in IL-1α-primed ARPE-19 cells with the proteasome and autophagy inhibitors MG-132 and bafilomycin A1, respectively. Intracellular caspase-1 activity was determined using a commercial caspase-1 activity kit and the FLICA assay. The levels of IL-1β were measured from cell culture medium samples by ELISA. Cell viability was monitored by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and lactate dehydrogenase (LDH) measurements. Our findings show that TAS-116 could prevent the activation of caspase-1, subsequently reducing the release of mature IL-1β. TAS-116 has a better in vitro therapeutic index than geldanamycin. In summary, TAS-116 appears to be a well-tolerated Hsp90 inhibitor, with the capability to prevent the activation of the NLRP3 inflammasome in human RPE cells.

Potential roles of natural products in the targeting of proteinopathic neurodegenerative diseases

Defective proteostasis is associated with the gradual accumulations of misfolded proteins and is a hallmark of many age-associated neurodegenerative diseases. In the aged brain, maintenance of the proteostasis network presents a substantial challenge, and its loss contributes to the onset and progression of neurological diseases associated with cognitive decline due to the generation of toxic protein aggregates, a process termed 'proteinopathy'. Emerging evidence suggests that reversing proteinopathies by boosting proteostasis might provide an effective means of preventing neurodegeneration. From this perspective, phytochemicals may play significant roles as potent modulators of the proteostasis network, as previous reports have suggested they can interact with various network components to modify pathologies and confer neuroprotection. This review focuses on some potent phytochemicals that directly or indirectly modulate the proteostasis network and on their possible molecular targets. In addition, we propose strategies for the natural product-based modulation of proteostasis machinery that target proteinopathies.

Glucocorticoid receptor-targeted liposomal delivery system for delivering small molecule ESC8 and anti-miR-Hsp90 gene construct to combat colon cancer

High mortality rate in colon cancer patients is often attributed to late diagnosis. To overcome the conventional chemotherapy associated challenges, chemotherapeutic drugs (single or combination) or genetic drugs are often delivered using ligand-modified delivery systems that selectively target over expressed receptors or particular receptors that act abnormally in cancer cells. In the current investigation, first we assessed anti-colon cancer effect of a cationic estrogenic molecule, ESC8 which was earlier shown to act against estrogen receptor (ER) ± breast cancer cells. We found that against both colon and breast cancer cells the anticancer activity is intervened by AMPK-mTOR pathway and at the same time it acts as anti-angiogenic agent. It also showed enhancement of mesenchymal-to-epithelial (MET) transition as well as reduction of cyclin D in both cells. Earlier we demonstrated the use of glucocorticoid receptor (GR) targeted cationic liposomal delivery system carrying anti-Hsp90 plasmid and ESC8 to act as potent anti-skin cancer therapeutics. As ESC8 demonstrated anti-colon cancer effect in vitro, in here, we used the same GR-targeted liposomal formulation but carrying a more fusogenic cationic lipid D1 and used against colon tumor orthotopic model in mice. We show that GR targeted formulation (D1XE-Hsp90) exhibited efficient cellular uptake, transfection and selective cytotoxicity in colon cancer cells, tumor-targeted bio-distribution and enhanced survivability, reduced tumor size in orthotopic colon tumor-bearing mice. The tumor sections exhibited reduced tumor proliferation as well as neo-vascularization, thus supporting the holistic antitumor effect of the D1XE-Hsp90 formulation. Over all our results establish the GR-targeted D1XE-Hsp90 formulation as potent anti-colon cancer therapeutics.

Functions and Therapeutic Potential of Extracellular Hsp60, Hsp70, and Hsp90 in Neuroinflammatory Disorders

Neuroinflammation is implicated in central nervous system (CNS) diseases, but the molecular mechanisms involved are poorly understood. Progress may be accelerated by developing a comprehensive view of the pathogenesis of CNS disorders, including the immune and the chaperone systems (IS and CS). The latter consists of the molecular chaperones; cochaperones; and chaperone cofactors, interactors, and receptors of an organism and its main collaborators in maintaining protein homeostasis (canonical function) are the ubiquitin–proteasome system and chaperone-mediated autophagy. The CS has also noncanonical functions, for instance, modulation of the IS with induction of proinflammatory cytokines. This deserves investigation because it may be at the core of neuroinflammation, and elucidation of its mechanism will open roads toward developing efficacious treatments centered on molecular chaperones (i.e., chaperonotherapy). Here, we discuss information available on the role of three members of the CS—heat shock protein (Hsp)60, Hsp70, and Hsp90—in IS modulation and neuroinflammation. These three chaperones occur intra- and extracellularly, with the latter being the most likely involved in neuroinflammation because they can interact with the IS. We discuss some of the interactions, their consequences, and the molecules involved but many aspects are still incompletely elucidated, and we hope that this review will encourage research based on the data presented to pave the way for the development of chaperonotherapy. This may consist of blocking a chaperone that promotes destructive neuroinflammation or replacing or boosting a defective chaperone with cytoprotective activity against neurodegeneration.

Mesenchymal stem cell-derived extracellular vesicles promote microglial M2 polarization after subarachnoid hemorrhage in rats and involve the AMPK/NF-κB signaling pathway

Subarachnoid hemorrhage (SAH) is an acute and severe disease with high disability and mortality. Inflammatory reactions have been proven to occur throughout SAH. Extracellular vesicles derived from mesenchymal stem cells (MSCs-EVs) have shown broad potential for the treatment of brain dysfunction and neuroprotective effects through neurogenesis and angiogenesis after stroke. However, the mechanisms of EVs in neuroinflammation during the acute phase of SAH are not well known. Our present study was designed to investigate the effects of MSCs-EVs on neuroinflammation and the polarization regulation of microglia to the M2 phenotype and related signaling pathways after SAH in rats. The SAH model was induced by an improved method of intravascular perforation, and MSCs-EVs were injected via the tail vein. Post-SAH assessments included neurobehavioral tests as well as brain water content, immunohistochemistry, PCR and Western blot analyses. Our results showed that MSCs-EVs alleviated the expression of inflammatory cytokines in the parietal cortex and hippocampus 24 h and 48 h after SAH and that MSCs-EVs inhibited NF-κB and activated AMPK to reduce inflammation after SAH. Furthermore, MSC-EVs regulated the polarization of microglia toward the M2 phenotype by downregulating interleukin-1β, cluster of differentiation 16, cluster of differentiation 11b, and inducible nitric oxide synthase and upregulating the expression of cluster of differentiation 206 and arginase-1. Additionally, MSCs-EVs inhibited the neuroinflammatory response and had neuroprotective effects in the brain tissues of rats after SAH. This study may support their use as a potential treatment strategy for early SAH in the future.

INT-777 attenuates NLRP3-ASC inflammasome-mediated neuroinflammation via TGR5/cAMP/PKA signaling pathway after subarachnoid hemorrhage in rats

BACKGROUND

Inflammasome-mediated neuroinflammation plays an important role in the pathogenesis of early brain injury (EBI) following subarachnoid hemorrhage (SAH). The activation of the TGR5 receptor has been shown to be neuroprotective in a variety of neurological diseases. This study aimed to investigate the effects of the specific synthetic TGR5 agonist, INT-777, in attenuating NLRP3-ASC inflammasome activation and reducing neuroinflammation after SAH.

METHODS

One hundred and eighty-four male Sprague Dawley rats were used. SAH was induced by the endovascular perforation. INT-777 was administered intranasally at 1 h after SAH induction. To elucidate the signaling pathway involved in the effect of INT-777 on inflammasome activation during EBI, TGR5 knockout CRISPR and PKA inhibitor H89 were administered intracerebroventricularly and intraperitoneally at 48 h and 1 h before SAH. The SAH grade, short- and long-term neurobehavioral assessments, brain water content, western blot, immunofluorescence staining, and Nissl staining were performed.

RESULTS

The expressions of endogenous TGR5, p-PKA, and NLRP3-ASC inflammasome were increased after SAH. INT-777 administration significantly decreased NLRP3-ASC inflammasome activation in microglia, reduced brain edema and neuroinflammation, leading to improved short-term neurobehavioral functions at 24 h after SAH. The administration of TGR5 CRISPR or PKA inhibitor (H89) abolished the anti-inflammation effects of INT-777, on NLRP3-ASC inflammasome, pro-inflammatory cytokines (IL-6, IL-1β, and TNF-a), and neutrophil infiltration at 24 h after SAH. Moreover, early administration of INT-777 attenuated neuronal degeneration in hippocampus on 28 d after SAH.

CONCLUSIONS

INT-777 attenuated NLRP3-ASC inflammasome-dependent neuroinflammation in the EBI after SAH, partially via TGR5/cAMP/PKA signaling pathway. Early administration of INT-777 may serve as a potential therapeutic strategy for EBI management in the setting of SAH.

α-Cyperone Confers Antidepressant-Like Effects in Mice via Neuroplasticity Enhancement by SIRT3/ROS Mediated NLRP3 Inflammasome Deactivation

α-Cyperone (Cy) is a major active compound of Cyperus rotundus that has various pharmacological activities. But whether Cy possesses antidepressant effect is unknown. In this study, we exposed mice to chronic unpredictable mild stress (CUMS) with or without intervention with Cy. Our results showed that Cy significantly improved the depressive phenotypes in sucrose preference test, tail suspension test and forced swimming test. Meanwhile, increased SIRT3 expression, reduced ROS production and activated NF-κB signal were detected in the hippocampus of mice. NLRP3 inflammasome related proteins including NLRP3, ASC, Caspase-1, IL-1β, IL-18 and GSDMD-N were downregulated after Cy administration. Synaptic proteins including Synapsin-1 and PSD-95 and dendritic spine density were improved after Cy treatment. Moreover, the protective effects of Cy in CUMS mice were compromised when co-administrated with SIRT3 inhibitor 3-TYP. Taken together, these findings suggested that Cy has therapeutic potential for treating depression and that this antidepressant effect may be attributed to SIRT3 stimulated neuroplasticity enhancement by suppressing NLRP3 inflammasome.

DsbA-L mediated renal tubulointerstitial fibrosis in UUO mice

Recent studies have reported that upregulation of disulfide-bond A oxidoreductase-like protein (DsbA-L) prevented lipid-induced renal injury in diabetic nephropathy (DN). However, the role and regulation of proximal tubular DsbA-L for renal tubulointerstitial fibrosis (TIF) remains unclear. In current study, we found that a proximal tubules-specific DsbA-L knockout mouse (PT-DsbA-L-KO) attenuated UUO-induced TIF, renal cell apoptosis and inflammation. Mechanistically, the DsbA-L interacted with Hsp90 in mitochondria of BUMPT cells which activated the signaling of Smad3 and p53 to produce connective tissue growth factor (CTGF) and then resulted in accumulation of ECM of BUMPT cells and mouse kidney fibroblasts. In addition, the progression of TIF caused by UUO, ischemic/reperfusion (I/R), aristolochic acid, and repeated acute low-dose cisplatin was also alleviated in PT-DsbA-L-KO mice via the activation of Hsp90 /Smad3 and p53/CTGF axis. Finally, the above molecular changes were verified in the kidney biopsies from patients with obstructive nephropathy (Ob). Together, these results suggest that DsbA-L in proximal tubular cells promotes TIF via activation of the Hsp90 /Smad3 and p53/CTGF axis.

DsbA-L upregulation prevents lipid-induced renal injury in diabetic nephropathy. Here, the authors show that DsbA-L knockout attenuates tubulointerstitial fibrosis in mice, and show that this occurs via activation of Smad3 and p53, which result in modulation of CTGF, a regulator of kidney fibrosis.

Targeting CCL20 inhibits subarachnoid hemorrhage-related neuroinflammation in mice

Recent evidence suggests that CC chemokine ligand 20 (CCL20) is upregulated after subarachnoid hemorrhage (SAH). Here, we investigated the functions of CCL20 in SAH injury and its underlying mechanisms of action. We found that CCL20 is upregulated in an SAH mouse model and in cultured primary microglia and neurons. CCL20-neutralizing antibody alleviated SAH-induced neurological deficits, decreased brain water content and neuronal apoptosis, and repressed microglial activation. We observed increased levels of CCL20, CC chemokine receptor 6 (CCR6), interleukin 1 beta (IL-1β), and tumor necrosis factor alpha (TNF-α), as well as of microglial activation in microglia treated with oxyhemoglobin (OxyHb). CCL20 or CCR6 knockdown reversed the effects of OxyHb on microglia. Conditioned medium from OxyHb-treated microglia induced neuronal apoptosis, while the percentage of apoptotic neurons in the conditioned medium from microglia transfected with CCL20 siRNA or CCR6 siRNA was decreased. We observed no decrease in OxyHb-induced apoptosis in CCL20-knockdown neurons. Conditioned medium from OxyHb-treated neurons led to microglial activation and induced CCR6, IL-1β and TNF-α expression, while CCL20 knockdown in neurons or CCR6 knockdown in microglia reversed those effects. Our results thus suggest CCL20 may be targeted to elicit therapeutic benefits after SAH injury.

HSP70-Mediated NLRP3 Inflammasome Suppression Underlies Reversal of Acute Kidney Injury Following Extracellular Vesicle and Focused Ultrasound Combination Therapy

Acute kidney injury (AKI) is the abrupt loss of renal function, for which only supportive therapies exist. Mesenchymal stromal cell (MSC)-derived extracellular vesicles (EVs) have been shown to be therapeutically effective in treating AKI by spurring endogenous cell proliferation and survival while suppressing inflammation. Pre-treating kidneys with pulsed focused ultrasound (pFUS) has also been shown to enhance MSC therapy for AKI, but its role in MSC-derived EV therapy remains unexplored. Using a mouse model of cisplatin-induced AKI, we show that combination therapy with pFUS and EVs restores physiological and molecular markers of kidney function, more so than either alone. Both pFUS and EVs downregulate heat shock protein 70 (HSP70), the NLRP3 inflammasome, and its downstream pro-inflammatory cytokines IL-1β and IL-18, all of which are highly upregulated in AKI. In vitro knockdown studies suggest that HSP70 is a positive regulator of the NLRP3 inflammasome. Our study therefore demonstrates the ability of pFUS to enhance EV therapy for AKI and provides further mechanistic understanding of their anti-inflammatory and regenerative effects.

Chemokine receptor 4 expression is correlated with the occurrence and prognosis of gastric cancer

Gastric cancer (GC) is a common tumor with a low 5-year survival rate. The chemokine receptor 4 (CXCR4) protein contributes to the progression and prognosis of GC, but the relationship between CXCR4 and immune infiltration, somatic copy number alteration (SCNA), tumor purity, tumor mutation burden (TMB), cytolytic activity (CYT), and drug sensitivity in GC is poorly understood. This study aimed to systematically explore the role of CXCR4 in GC. Microarray and RNA-seq data were collected from the Gene Expression Omnibus and The Cancer Genome Atlas. Our analysis shows that CXCR4 is correlated with various types of immune cells. Patients with high CXCR4 expression had a higher fraction of B cells and CD8+ T cells, and a lower fraction of CD4+ T cells. In addition, high CXCR4 expression was associated with more advanced tumor stage, worse prognosis and higher stromal score, immune score, and cytolytic activity (P < 0.05). High CXCR4 expression also correlated with lower tumor purity and TMB. In summary, our analyses suggest that CXCR4 may affect the progression and prognosis of GC by influencing immune infiltration, TMB, CYT, tumor purity, and drug sensitivity.

Dl-3-n-Butylphthalide promotes neovascularization and neurological recovery in a rat model of intracerebral hemorrhage

Background

Cerebral stroke occurs following ischemic and hemorrhagic lesions in the brain. Survival and recovery of stroke patients depend on the severity of the initial injury but also the therapeutic approaches applied for emergent lifesaving and continuing post-stroke management. Dl-3-n-Butylphthalide (NBP), an active compound derived from Chinese celery seeds, has shown clinical efficacy in the treatment of ischemic cerebral stroke.

Results

In the present study we explored the therapeutic effect of NBP in a rat model of intracerebral hemorrhage (ICH), focusing on its potential role in promoting neovascularization in the perihemorrhagic zone. ICH was induced in male Sprague-Dawley rats by unilateral injection of autologous blood into the globus pallidus, with sham-operated (Sham group), vehicle-treated (ICH) and NBP-treated (at 10 and 25 mg/kg/Bid, p.o., ICH + NBP10 and ICH + NBP25, respectively) groups examined behaviorally, macroscopically, histologically and biochemically at 1, 3, 7 and 15 days (d) post operation. Rats in the ICH + NBP10 and ICH + NBP25 groups showed reduced Longa’s motor scores relative to the ICH groups at the 3 and 7d time points, while the hematoma volume was comparable in the two NBP relative to the ICH groups as measured at 7d and 15d. In the perihemorrhagic zone, the numeric density of blood vessels immunolabeled by CD34, an angiogenic marker, was greater in the ICH + NBP10 and ICH + NBP25 than ICH groups, more so in the higher dosage group, at 1, 3, 7 and 15d. Levels of the vascular endothelial growth factor (VEGF) and angiopoietins-2 (Ang-2) proteins were elevated in the NBP groups relative to the sham and vehicle controls in immunoblotting of tissue lysates from the injection region.

Conclusion

These results suggest that NBP can alleviate neurological defects following experimentally induced local brain hemorrhage, which is associated with a potential role of this drug in promoting neovascularization surrounding the bleeding loci.

Inhibition of HSP90 and Activation of HSF1 Diminish Macrophage NLRP3 Inflammasome Activity in Alcohol-Associated Liver Injury

BACKGROUND

Activation of NLRP3 in liver macrophages contributes to alcohol-associated liver disease (ALD). Molecular chaperone heat shock protein (HSP) 90 facilitates NLRP3 inflammasome activity during infections and inflammatory diseases. We previously reported that HSP90 is induced in ALD and regulates proinflammatory cytokines, tumor necrosis factor alpha, and IL-6. Whether HSP90 affects IL-1β and IL-18 regulated by NLRP3 inflammasome in ALD is unknown. Here, we hypothesize that HSP90 modulated NLRP3 inflammasome activity and affects IL-1β and IL-18 secretion in ALD.

METHODS

The expression of HSP90AA1 and NLRP3 inflammasome genes was evaluated in human alcoholic livers and in mouse model of ALD. The importance of HSP90 on NLRP3 inflammasome activation in ALD was evaluated by administering HSP90 inhibitor, 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) to mice subjected to ALD, and in vitro to bone marrow-derived macrophages (BMDM) stimulated with LPS and ATP. The effect of activation of HSF1/HSPA1A axis during HSP90 inhibition or direct activation during heat shock of BMDMs on NLRP3 activity and secretion of downstream cytokines was evaluated.

RESULTS

We found positive correlation between induction of HSP90 and NLRP3 inflammasome genes in human alcoholic cirrhotic livers. Administration of 17-DMAG in mouse model of ALD significantly down-regulated NLRP3 inflammasome-mediated caspase-1 (CASP-1) activity and cytokine secretion, with reduction in ALD. 17-DMAG-mediated decrease in NLRP3 was restricted to liver macrophages. Using BMDMs, we show that inhibition of HSP90 prevented CASP-1 activity, and Gasdermin D (GSDMD) cleavage, important in release of active IL-1β and IL-18. Interestingly, activation of the heat shock factor 1 (HSF1)/HSPA1A axis, either during HSP90 inhibition or by heat shock, decreased NLRP3 inflammasome activity and reduced secretion of cytokines.

CONCLUSION

Our studies indicate that inhibition of HSP90 and activation of HSF1/HSPA1A reduce IL-1β and IL-18 via decrease in NLRP3/CASP-1 and GSDMD activity in ALD.

Mechanisms of neuroinflammation and inflammatory mediators involved in brain injury following subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disorder. Neuroinflammation is a critical cause of brain injury following SAH in both acute and chronic phases. While accumulating evidence has shown that therapies targeting neuroinflammation exerted beneficial effects in experimental SAH, there is little clinical evidence. One of the factors making neuroinflammation complicated is that inflammatory signaling pathways and mediators act as protective or detrimental responses at different phases. In addition, biomarkers to detect neuroinflammation are little known in clinical settings. In this review, first, we discuss how the inflammatory signaling pathways contribute to brain injury and other secondary pathophysiological changes in SAH. Damage-associated molecular patterns arising from mechanical stress, transient global cerebral ischemia, red blood cell breakdown and delayed cerebral ischemia following SAH trigger to activate pattern recognition receptors (PRRs) such as Toll-like receptors, nucleotide-binding oligomerization domain-like receptors, and receptors for advanced glycation end products. Most of PRRs activate common downstream signaling transcriptional factor nuclear factor-κΒ and mitogen-activated protein kinases, releasing pro-inflammatory mediators and cytokines. Next, we focus on how pro-inflammatory substances play a role during the course of SAH. Finally, we highlight an important inducer of neuroinflammation, matricellular protein (MCP). MCPs are a component of extracellular matrix and exert beneficial and harmful effects through binding to receptors, other matrix proteins, growth factors, and cytokines. Treatment targeting MCPs is being proved efficacious in pre-clinical models for preventing brain injury including neuroinflammation in SAH. In addition, MCPs may be a candidate of biomarkers predicting brain injury following SAH in clinical settings.

HSP70 and HSP90 in neurodegenerative diseases

Molecular chaperones have a role to stabilize proteins or assist them in reaching their native fold. Heat shock proteins (HSPs) are a family of molecular chaperons that protect proteins from cellular stress during the assembly of protein complexes and also prevent the proteins from aggregation and disassembly. The immediate increase of HSPs is crucial for cellular adaptation to environmental changes and protection of other proteins from denaturation, thereby maintaining the cellular homeostasis and increasing the longevity of an organism. HSP70 and HSP90 are the most studied HSPs in this very large HSP family. Notably, HSP90 also stabilizes the disease-related proteins in neurodegenerative disorders. Therefore, small molecules that inhibit the HSP90 but also increase the HSP70 has been tested as potential drugs for neurodegenerative disorders.

Recombinant Human Milk Fat Globule-Epidermal Growth Factor 8 Attenuates Microthrombosis after Subarachnoid Hemorrhage in Rats

BACKGROUND

Microthrombosis after subarachnoid hemorrhage has an adverse effect on prognosis. Milk fat globule-epidermal growth factor 8 promotes phagocytosis of phagocytic cells and may reduce microthrombosis. This study investigated the effects of recombinant human milk fat globule-epidermal growth factor 8 on microthrombosis and neurological function after subarachnoid hemorrhage.

METHODS

Rats subarachnoid hemorrhage model was induced by intravascular puncture method. Western blot was performed to measure the expression of endogenous milk fat globule-epidermal growth factor 8 after subarachnoid hemorrhage. Microthrombosis was quantified by microthrombi count using immunohistochemistry and immunofluorescence. The neuroprotective effect of recombinant human milk fat globule-epidermal growth factor 8 administration was evaluated by modified Garcia score, beam balance, Rotarod test, and Morris water maze.

RESULTS

Endogenous milk fat globule-epidermal growth factor 8 protein level increased after subarachnoid hemorrhage. Microthrombosis was significantly increased in subarachnoid hemorrhage rats brain, while recombinant human milk fat globule-epidermal growth factor 8 dramatically reduced microthrombosis as well as improve short- and long- term neurobehavior after subarachnoid hemorrhage.

CONCLUSIONS

Recombinant human milk fat globule-epidermal growth factor 8 reduces microthrombosis and improves neurological function after subarachnoid hemorrhage, which may be an effective strategy for treating subarachnoid hemorrhage.

Recent Advances in Stem Cell Research in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke with significant morbidity and mortality, and it often leads to poor clinical outcome. Although great efforts have been made toward animal and clinical studies, optimal therapy of SAH remains a challenge for scientists and clinicians. Increasing evidence suggests that stem-cell-based therapies may provide innovative approaches for treatment of SAH-related disability. In this review, we summarized the recent advances in stem cell research in SAH. Neuroregeneration after SAH could be conducted by the activation of endogenous neural stem cells (NSCs), transplantation of external stem cells, or reprogramming non-neuronal cell to neurons. The potential mechanism and signaling pathways, as well as the efficiency and safety of these stem cell treatments, were discussed in detail. Although lots of challenges remain for translating the laboratory findings and technologies into clinical therapies, these research studies provided the foundation and guidance for using different resources of stem cells as a brain repair strategy after SAH.

Heat Shock Proteins and Inflammasomes

Heat shock proteins (HSP) regulate inflammation in many physiological contexts. However, inflammation is a broad process, involving numerous cytokines produced by different molecular pathways with multiple functions. In this review, we focused on the particular role of HSP on the inflammasomes intracellular platforms activated by danger signals and that enable activation of inflammatory caspases, mainly caspase-1, leading to the production of the pro-inflammatory cytokine IL-1β. Interestingly, some members of the HSP family favor inflammasomes activation whereas others inhibit it, suggesting that HSP modulators for therapeutic purposes, must be carefully chosen.

P2X7 Interactions and Signaling - Making Head or Tail of It

Extracellular adenine nucleotides play important roles in cell-cell communication and tissue homeostasis. High concentrations of extracellular ATP released by dying cells are sensed as a danger signal by the P2X7 receptor, a non-specific cation channel. Studies in P2X7 knockout mice and numerous disease models have demonstrated an important role of this receptor in inflammatory processes. P2X7 activation has been shown to induce a variety of cellular responses that are not usually associated with ion channel function, for example changes in the plasma membrane composition and morphology, ectodomain shedding, activation of lipases, kinases, and transcription factors, as well as cytokine release and apoptosis. In contrast to all other P2X family members, the P2X7 receptor contains a long intracellular C-terminus that constitutes 40% of the whole protein and is considered essential for most of these effects. So far, over 50 different proteins have been identified to physically interact with the P2X7 receptor. However, few of these interactions have been confirmed in independent studies and for the majority of these proteins, the interaction domains and the physiological consequences of the interactions are only poorly described. Also, while the structure of the P2X7 extracellular domain has recently been resolved, information about the organization and structure of its C-terminal tail remains elusive. After shortly describing the structure and assembly of the P2X7 receptor, this review gives an update of the identified or proposed interaction domains within the P2X7 C-terminus, describes signaling pathways in which this receptor has been involved, and provides an overlook of the identified interaction partners.

The NLRP3 Inflammasome: An Overview of Mechanisms of Activation and Regulation

The NLRP3 inflammasome is a critical component of the innate immune system that mediates caspase-1 activation and the secretion of proinflammatory cytokines IL-1β/IL-18 in response to microbial infection and cellular damage. However, the aberrant activation of the NLRP3 inflammasome has been linked with several inflammatory disorders, which include cryopyrin-associated periodic syndromes, Alzheimer's disease, diabetes, and atherosclerosis. The NLRP3 inflammasome is activated by diverse stimuli, and multiple molecular and cellular events, including ionic flux, mitochondrial dysfunction, and the production of reactive oxygen species, and lysosomal damage have been shown to trigger its activation. How NLRP3 responds to those signaling events and initiates the assembly of the NLRP3 inflammasome is not fully understood. In this review, we summarize our current understanding of the mechanisms of NLRP3 inflammasome activation by multiple signaling events, and its regulation by post-translational modifications and interacting partners of NLRP3.

The role and therapeutic potential of heat shock proteins in haemorrhagic stroke

Heat shock proteins (HSPs) are induced after haemorrhagic stroke, which includes subarachnoid haemorrhage (SAH) and intracerebral haemorrhage (ICH). Most of these proteins function as neuroprotective molecules to protect cerebral neurons from haemorrhagic stroke and as markers to indicate cellular stress or damage. The most widely studied HSPs in SAH are HSP70, haeme oxygenase-1 (HO-1), HSP20 and HSP27. The subsequent pathophysiological changes following SAH can be divided into two stages: early brain injury and delayed cerebral ischaemia, both of which determine the outcome for patients. Because the mechanisms of HSPs in SAH are being revealed and experimental models in animals are continually maturing, new agents targeting HSPs with limited side effects have been suggested to provide therapeutic potential. For instance, some pharmaceutical agents can block neuronal apoptosis signals or dilate cerebral vessels by modulating HSPs. HO-1 and HSP70 are also critical topics for ICH research, which can be attributed to their involvement in pathophysiological mechanisms and therapeutic potential. However, the process of HO-1 metabolism can be toxic owing to iron overload and the activation of succedent pathways, for example, the Fenton reaction and oxidative damage; the overall effect of HO-1 in SAH and ICH tends to be protective and harmful, respectively, given the different pathophysiological changes in these two types of haemorrhagic stroke. In the present study, we focus on the current understanding of the role and therapeutic potential of HSPs involved in haemorrhagic stroke. Therefore, HSPs may be potential therapeutic targets, and new agents targeting HSPs are warranted.