Urolithin A promotes mitophagy and suppresses NLRP3 inflammasome activation in lipopolysaccharide-induced BV2 microglial cells and MPTP-induced Parkinson's disease model

Small extracellular vesicles from adipose derived stem cells alleviate microglia activation and improve motor deficit of Parkinson's disease via miR-100-5p/DTX3L/STAT1 signaling axis

Dopaminergic neuron loss caused by microglia activation is an important pathological factor of Parkinson's disease (PD). Previously, we reported that small extracellular vesicle from adipose derived stem cells (ADSC-sEVs) could inhibit the activation of microglia and protect neuron apoptosis from microglia activation. However, whether ADSC-sEVs have protective effect on the motor deficit of PD mouse and the exact mechanism remains unknown. In this study, ADSC-sEVs were delivered to experimental model of Parkinson's disease by tail vein injection to explore the in vivo effect of ADSC-sEVs on PD. Next, the potential key microRNA in ADSC-sEVs was screened by RNA sequencing (RNA-seq), and the exact mechanism was further explored. We found that ADSC-sEVs greatly alleviated the activation of microglia and reduced the loss of dopaminergic neurons in the substantia nigra of PD mice, the motor deficit was also significantly improved. By RNA-seq analysis, miR-100-5p was verified as a potential microRNA in this process, because knockdown of miR-100-5p in ADSC-sEVs weakened the protective effect of ADSC-sEVs on PD mouse as well as the anti-inflammatory effect on microglia activation. Finally, we found that miR-100-5p could target Deltex E3 ubiquitin ligase 3 L (DTX3L) and suppress its expression, which then decreased the expression and phosphorylation of Signal Transducers and Activators of Transcription 1 (STAT1), as well as alleviating the activation of microglia. Our findings illustrate that ADSC-sEVs are an effective therapy for PD, and it could be a promising therapy for the treatment of PD.

P2Y6R Inhibition Induces Microglial M2 Polarization by Promoting PINK1/Parkin-Dependent Mitophagy After Spinal Cord Injury

Secondary injury presents a significant hurdle to neural regeneration following spinal cord injury (SCI), primarily driven by inflammation in which microglial cells play a crucial role. Despite the growing interest in mitophagy, studies on its occurrence post-spinal cord injury, particularly within microglial cells, are scarce. While P2Y6R has been implicated in inflammation regulation in various neurological conditions, its specific role in SCI remains uncertain. Our study revealed an upregulation of P2Y6R expression following SCI notably in microglial cells. Treatment with the P2Y6R-specific inhibitor, MRS2578, in mice facilitated M2 polarization of microglial cells and alleviated secondary damage, ultimately enhancing neural regeneration and functional recovery. In an in vitro BV2 inflammation model, our findings indicate that P2Y6R inhibition induced M2 polarization of BV2 cells and reduced neuroinflammation through PINK/Parkin-dependent mitophagy activation. In summary, our results underscore the potential of P2Y6R inhibition in promoting mitophagy-induced M2 polarization of microglial cells, thereby ameliorating secondary injury following spinal cord injury.

Molecular mechanism of PANoptosis and programmed cell death in neurological diseases

PANoptosis represents a highly coordinated inflammatory programmed cell death governed by the assembly and activation of PANoptosome, which strategically integrate core molecular elements from pyroptosis, apoptosis, and necroptosis. The triple-component cell death pathways set themselves apart from alternative regulated cell death mechanisms through their unique capacity to concurrently integrate and process molecular signals derived from multiple death-signaling modalities, thereby coordinating a multifaceted cellular defense system against diverse pathological insults. Pathogen-associated molecular patterns synergistically interact with cytokine storms, and oncogenic stress to active PANoptosis, establishing this programmed cell death pathway as a critical nexus in inflammatory pathogenesis and tumor immunomodulation. This molecular crosstalk highlights PANoptosis as a promising therapeutic target for managing immune-related disorders and malignant transformation. Emerging evidence links PANoptosis to neuroinflammatory disorders through dysregulated crosstalk between programmed death pathways (apoptosis, necroptosis, pyroptosis) and accidental necrosis, driving neuronal loss and neural damage. Single-cell transcriptomics reveals spatially resolved PANoptosis signatures in Alzheimer's hippocampal microenvironments and multiple sclerosis demyelinating plaques, with distinct molecular clusters correlating to quantifiable neuroinflammatory metrics. Emerging PANoptosis-targeted therapies show preclinical promise in alleviating neurovascular dysfunction while preserving physiological microglial surveillance functions. Accumulating evidence linking dysregulated cell death pathways (particularly PANoptosis) to neurological disorders underscores the urgency of deciphering its molecular mechanisms and developing precision modulators as next-generation therapies. This review systematically deciphers PANoptosome assembly mechanisms and associated cell death cascades, evaluates their pathological roles in neurological disorders through multiscale regulatory networks, and proposes PANoptosis-targeted therapeutic frameworks to advance precision neurology.

Novel pH-responsive lipid nanoparticles deliver UA-mediated mitophagy and ferroptosis for osteoarthritis treatment

Synovial inflammation plays a crucial role in osteoarthritis (OA) development, leading to chronic inflammation and cartilage destruction. Although targeting synovitis can alleviate OA, clinical outcomes have been disappointing due to poor drug targeting and joint cavity heterogeneity. This study presents pH-responsive lipid nanoparticles (LNPs@UA), loaded with Urolithin A (UA), as a potential OA treatment. LNPs@UA showed uniform particle size, low zeta potential, and effective mitochondria-targeting and pH-responsive capabilities. In vitro, LNPs@UA reduced reactive oxygen species (ROS), pro-inflammatory factors (IL-1β, IL-6, TNF-α), and promoted M2 macrophage polarization. It improved mitochondrial structure, enhanced autophagy, and inhibited ferroptosis. In vivo, LNPs@UA alleviated OA progression in an ACLT-induced OA mouse model. Transcriptomic analysis revealed inhibition of NF-κB signaling and activation of repair pathways. These results suggest LNPs@UA could offer a promising therapeutic approach for OA.

Inhalation of Acori Tatarinowii Rhizoma essential oil alleviates dyskinesia in Parkinson's disease rats through the regulation of neuroinflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Acorus tatarinowii Rhizoma, a traditional Chinese medicine known for opening the orifices and transforming phlegm, is used in the treatment of brain disorders. It is listed as the top grade in the famous herbal monograph Shennong Materia Medica Classic. Traditional Chinese medicine believes that Acorus tatarinowii Rhizoma has a good advantage in the treatment of nervous system diseases, and modern research has also found that the essential oil of Acorus tatarinowii Rhizoma is the main component that plays a neuroprotective role and plays an important role in the treatment of Parkinson's disease.

AIM OF THE STUDY

This study aims to explore the effects and mechanisms of essential oil of Acorus tatarinowii Rhizoma (EOAT) on LPS-induced BV2 cell damage and Rotenone-induced Parkinson's disease (PD) rat models.

MATERIALS AND METHODS

In this experiment, the components of EOAT were identified by GC-MS. LPS was used to induce the overactivation of BV2 microglia, and rotenone was injected subcutaneously to induce Parkinson's disease in rats. Then, the expression of inflammatory factors and IBA-1 in cell was evaluated, and the effects of EOAT treatment were assessed on motor function, inflammatory factors, neurotransmitters, TH, α-Syn, and pathways and inflammation-related mRNA in rats.

RESULTS

GC-MS analysis obtained 24 components, among which β-Asarone and α-Asarone had the highest contents. In vitro experiments showed that after 2 h of EOAT intervention, the inflammatory factors TNF-α and IL-6 in the supernatant of LPS-induced BV2 cells were significantly reduced. The IF results showed that after EOAT intervention, the expression of IBA-1 protein in BV2 cells was significantly reduced. In animal experiments, rotenone injection in model rats led to a decrease in motor function, while inhalation of EOAT improved the motor ability of Parkinson's rats. In addition, Madopar and EOAT inhalation increased the levels of BDNF and DA in brain tissue and reduced the levels of IL-Iβ, TNF-α, and IL-6. IHC, IF, and WB analyses showed that the expression of TH protein in brain tissue of the Madopar group and the EOAT group was significantly increased, and the expression level of α-syn was reduced. RT-qPCR results showed that compared with the Model group, the levels of TLR2, MyD88, NF-κB, IL-1β, TNF-α, α-syn, and Bax in the substantia nigra and striatum of the Madopar group and the EOAT group were significantly down-regulated, and the levels of TH and Bcl-2 were significantly up-regulated.

CONCLUSION

These findings suggest that EOAT can prevent LPS from damaging BV2 cells and significantly improve the motor function of PD rats and lessen neuroinflammation. The anti-Parkinson's mechanism of EOAT is primarily dependent on the regulation of the TLR2/MyD88/NF-κB signaling pathway.

Appeal of Urolithins from Synthesis to Biological Activities

Urolithins (Uros), a series of natural polyphenols derived from ellagic acid through gut bacteria metabolism, have gathered significant attention due to their diverse bioactivities such as maintaining mitochondrial health and anti-inflammatory and antioxidative effects. However, the ability to metabolize Uros varies among individuals. This Review provides a comprehensive insight into the synthesis, encapsulation and bioactivities of Uros, focusing on their biotransformation in vivo. We highlight the critical role of gut microbiota in the biotransformation of urolithins, including primary bacterial species such as Gordonibacter urolithinfaciens, Enterocloster bolteae and Enterococcus faecium. Furthermore, the therapeutic potential of Uros in alleviating neurodegenerative diseases, cancer, and Duchenne muscular dystrophy is discussed. Finally, several encapsulation strategies for enhancing the solubility and bioavailability of Uros are summarized. Future research direction includes identifying key genes involved in Uros biotransformation, elucidating the bioactive mechanisms of Uros, and improving their bioavailability. In conclusion, we synthesized biosynthetic pathways and bioactive properties of Uros for better utilization in health management.

Therapeutic potential and limitation of condensed and hydrolyzed tannins in Parkinson's disease

Parkinson's disease is a complex neurodegenerative disorder characterized by neuroinflammation, mitochondrial dysfunction, and the accumulation of misfolded proteins such as α-synuclein. This review explores the therapeutic potential of tannins, particularly proanthocyanidins and hydrolyzable tannins from grape seeds, in alleviating Parkinson's disease pathology. Condensed tannins exhibit significant antioxidant properties, can cross the blood-brain barrier, reduce oxidative stress, upregulate antioxidant proteins, and prevent neuronal apoptosis. Hydrolyzable tannins, through their unique chemical structure, further help reduce neuroinflammation and improve mitochondrial function. Both types of tannins can modulate inflammatory responses and enhance mitochondrial integrity, addressing key aspects of Parkinson's disease pathogenesis. Tannins possess excellent neuroprotective effects, representing a promising therapeutic approach. However, due to their chemical nature and structural characteristics, the bioavailability of tannins in the human body remains low. Current methods to enhance their bioavailability are limited. Further exploration is needed to improve their bioavailability and strengthen their potential clinical applications. Based on this, new Parkinson's disease treatment strategies can be developed, warranting in-depth research and clinical validation.

Discovery of undescribed schinortriterpenoids from Schisandra chinensis by molecular networking and their neuroprotective effects

The dried, ripe fruit of Schisandra chinensis (Turcz.) Baill has significant nutritional as well as medicinal value and has been used in traditional Chinese medicine for centuries. Schinortriterpenoids (SNTs) are a distinct class of highly oxygenated and rearranged terpenoids exclusively derived from plants belonging to the Schisandraceae family. In this study, nine previously undescribed (1-9) and 20 known SNTs (10-29) were isolated from a Schisandra chinensis extract using the molecular networking technique. The structures of these compounds were elucidated using NMR, HR-ESI-MS, X-ray diffraction analysis, and quantum chemical calculations. Compounds 8, 11, 16, 18, and 24 exhibited significant anti-neuroinflammatory activity in LPS-stimulated microglial BV-2 cells, with IC50 values of 3.28 ± 0.86, 0.63 ± 0.32, 1.57 ± 0.27, 1.55 ± 0.50, and 1.86 ± 0.41 μM, respectively. Notably, the anti-neuroinflammatory activity of compound 11 was associated with the inhibition of the TLR4/NF-κB/NLRP3 signalling pathway.

Urolithin improves α-synuclein aggregation and DNMT1 expression in rotenone model of Parkinson's disease

α-synuclein aggregation is a key hallmark of Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). We examined the multi-targeting effects of urolithin (UA, UB, UC, UD, UE, UM5, and UM6) against α-synuclein aggregation using an in-silico and in-vitro approach. For in-silico analysis, several potential targets were selected like 1XQ8 (α-synuclein monomer), 1H1D (catechol-o-methyltransferase), 2BK3 (monoamine oxidase-B), 3IAM (NADH dehydrogenase), 4I5I (Sirtuin-1), and 5WVO [DNA methyltransferase-1], which play key role in α-synuclein aggregation, levodopa degradation, and mitochondrial dysfunction. In protein-protein docking analysis, 5HF9 (acetylcholinesterase, AChE) was found to interact with 1XQ8 dimer, forming a more stable complex with two additional H-bonds and one salt bridge, which indicates AChE's role as a nucleator in α-synuclein aggregation. In ligand docking and molecular dynamic studies, urolithin-A (UA) formed a more stable complex with 1XQ8, 4I5I, and 5WVO compared to specific inhibitor 1XQ8-ZPD2 and specific activator 4I5I-resveratrol. While other urolithins (UE, UM5, UC, and UD) displayed a more stable complex with 5HF9, 2BK3, 1H1D, and 3IAM compared to specific inhibitor 5HF9-physostigmine, 2BK3-selegiline, 1H1D-BIA, and specific activator 3IAM-resveratrol complexes, respectively. The blood-brain barrier permeability of UA (QPlogBB: -0.97) was predicted to be more than levodopa (QPlogBB: -1.44) and less than rotenone (QPlogBB: 0.08). DNMT1 inhibitor (5-Aza-dC) and rotenone robustly decreased the DNMT1 and α-synuclein expression in Neuro 2 A cells which was significantly reversed by UA treatment at 31.25 µM concentration. These findings indicate the potential of urolithins, specifically UA, UC, UD, UE, and UM5 against α-synuclein aggregation.

Urolithin A ameliorates schizophrenia-like behaviors and cognitive impairments in female rats by modulating NLRP3 signaling

The management of cognitive impairments in schizophrenia presents a considerable challenge, with a strong association between neuroinflammation and its progression. Urolithin A (UA) demonstrates important anti-inflammatory properties in multiple neurological disease models, contributing to the enhancement of cognitive deficits. However, it remains uncertain if UA can produce comparable neuroregulatory effects in female rat models of schizophrenia. Eight-week-old female Sprague Dawley rats received either 0.1 mg/kg of MK801 or volume-matched saline via intraperitoneal injection for 5 consecutive days. Furthermore, they were administered 150 mg/kg of UA through oral gavage for 4 weeks. Behavioral assessments were performed to evaluate cognitive function and behavior after UA treatment. Immunofluorescence staining was employed to assess microglial activity in the hippocampus, while Western blot analysis was conducted to investigate the expression of neuroinflammation-associated proteins. Prolonged exposure to MK801 induces schizophrenia-like behaviors and cognitive deficits in female rats. It also elevates the expression of NLRP3, Caspase-1, IL-1β, and IL-18 proteins in the hippocampus, accompanied by the activation of microglial cells. However, UA treatment can reverse the expression of these inflammatory proteins and the activation of microglial cells induced by MK801. This is the first study to evaluate the effects of UA on behavior and cognition in a female rat model of schizophrenia. The findings indicate that UA mitigates MK-801-induced cognitive deficits in female rats by inhibiting neuroinflammation and microglial activation via modulation of the NLRP3 signaling pathway. These findings offer preclinical data endorsing the possible application of UA as a dietary supplement to prevent cognitive deficits in schizophrenia.

Parkinson's Disease and the Microbiota-Gut-Brain Axis: Metabolites, Mechanisms, and Innovative Therapeutic Strategies Targeting the Gut Microbiota

The human gut microbiota is diverse and abundant and plays important roles in regulating health by participating in metabolism and controlling physiological activities. The gut microbiota and its metabolites have been shown to affect the functioning of the gut and central nervous system through the microbiota-gut-brain axis. It is well established that microbiota play significant roles in the pathogenesis and progression of Parkinson's disease (PD). Disorders of the intestinal microbiota and altered metabolite levels are closely associated with PD. Here, the changes in intestinal microbiota and effects of metabolites in patients with PD are reviewed. Potential mechanisms underlying intestinal microbiota disorders in the pathogenesis of PD are briefly discussed. Additionally, we outline the current strategies for the treatment of PD that target the gut microbiota, emphasizing the development of promising novel strategies.

Immune cell metabolic dysfunction in Parkinson's disease

Parkinson's disease (PD) is a multi-system disorder characterized histopathologically by degeneration of dopaminergic neurons in the substantia nigra pars compacta. While the etiology of PD remains multifactorial and complex, growing evidence suggests that cellular metabolic dysfunction is a critical driver of neuronal death. Defects in cellular metabolism related to energy production, oxidative stress, metabolic organelle health, and protein homeostasis have been reported in both neurons and immune cells in PD. We propose that these factors act synergistically in immune cells to drive aberrant inflammation in both the CNS and the periphery in PD, contributing to a hostile inflammatory environment which renders certain subsets of neurons vulnerable to degeneration. This review highlights the overlap between established neuronal metabolic deficits in PD with emerging findings in central and peripheral immune cells. By discussing the rapidly expanding literature on immunometabolic dysfunction in PD, we aim to draw attention to potential biomarkers and facilitate future development of immunomodulatory strategies to prevent or delay the progression of PD.

Dehydroervatamine as a promising novel TREM2 agonist, attenuates neuroinflammation

Microglia play a dual role in neuroinflammatory disorders that affect millions of people worldwide. These specialized cells are responsible for the critical clearance of debris and toxic proteins through endocytosis. However, activated microglia can secrete pro-inflammatory mediators, potentially exacerbating neuroinflammation and harming adjacent neurons. TREM2, a cell surface receptor expressed by microglia, is implicated in the modulation of neuroinflammatory responses. In this study, we investigated if and how Dehydroervatamine (DHE), a natural alkaloid, reduced the inflammatory phenotype of microglia and suppressed neuroinflammation. Our findings revealed that DHE was directly bound to and activated TREM2. Moreover, DHE effectively suppressed the production of pro-inflammatory cytokines, restored mitochondrial function, and inhibited NLRP3 inflammasome activation via activating the TREM2/DAP12 signaling pathway in LPS-stimulated BV2 microglial cells. Notably, silencing TREM2 abolished the suppression effect of DHE on the neuroinflammatory response, mitochondrial dysfunction, and NF-κB/NLRP3 pathways in vitro. Additionally, DHE pretreatment exhibited remarkable neuroprotective effects, as evidenced by increased neuronal viability and reduced apoptotic cell numbers in SH-SY5Y neuroblastoma cells co-cultured with LPS-stimulated BV2 microglia. Furthermore, in our zebrafish model, DHE pretreatment effectively alleviated behavioral impairments, reduced neutrophil aggregation, and suppressed neuroinflammation in the brain by regulating TREM2/NF-κB/NLRP3 pathways after intraventricular LPS injection. These findings provide novel insights into the potent protective effects of DHE as a promising novel TREM2 agonist against LPS-induced neuroinflammation, revealing its potential therapeutic role in the treatment of central nervous system diseases associated with neuroinflammation.

Protective role of mitophagy on microglia-mediated neuroinflammatory injury through mtDNA-STING signaling in manganese-induced parkinsonism

Manganese (Mn), the third most abundant transition metal in the earth's crust, has widespread applications in the emerging field of organometallic catalysis and traditional industries. Excessive Mn exposure causes neurological syndrome resembling Parkinson's disease (PD). The pathogenesis of PD is thought to involve microglia-mediated neuroinflammatory injury, with mitochondrial dysfunction playing a role in aberrant microglial activation. In the early stages of PD, PINK1/Parkin-mediated mitophagy contributes to the microglial inflammatory response via the cGAS/STING signaling pathway. Suppression of PINK1/Parkin-mediated mitophagy due to excessive Mn exposure exacerbates neuronal injury. Moreover, excessive Mn exposure leads to neuroinflammatory damage via the microglial cGAS-STING pathway. However, the precise role of microglial mitophagy in modulating neuroinflammation in Mn-induced parkinsonism and its underlying molecular mechanism remains unclear. Here, we observed that Mn-exposed mice exhibited neurobehavioral abnormalities and detrimental microglial activation, along with increased apoptosis of nerve cells, proinflammatory cytokines, and intracellular ROS. Furthermore, in vivo and in vitro experiments showed that excessive Mn exposure resulted in microglial mitochondrial dysfunction, manifested by increased mitochondrial ROS, decreased mitochondrial mass, and membrane potential. Additionally, with the escalating Mn dose, PINK1/Parkin-mediated mitophagy changed from activation to suppression. This was evidenced by decreased levels of LC3-II, PINK1, p-Parkin/Parkin, and increased levels of p62 protein expression level, as well as the colocalization between ATPB and LC3B due to excessive Mn exposure. Upregulation of mitophagy by urolithin A could mitigate Mn-induced mitochondrial dysfunction, as indicated by decreased mitochondrial ROS, increased mitochondrial mass, and membrane potential, along with improvements in neurobehavioral deficits and attenuated detrimental microglial activation. Using single-nucleus RNA-sequencing (snRNA-seq) analysis in the Mn-exposed mouse model, we identified the microglial cGAS-STING signaling pathway as a potential mechanism underlying Mn-induced neuroinflammation. This pathway is associated with an increase in cytosolic mtDNA levels, which activate STING signaling. These findings point to the induction of microglial mitophagy as a viable strategy to alleviate Mn-induced neuroinflammation through mtDNA-STING signaling.

Mitophagy in Neurodegenerative Diseases: Mechanisms of Action and the Advances of Drug Discovery

Neurodegenerative diseases (NDDs), such as Parkinson's disease (PD) and Alzheimer's disease (AD), are devastating brain diseases and are incurable at the moment. Increasing evidence indicates that NDDs are associated with mitochondrial dysfunction. Mitophagy removes defective or redundant mitochondria to maintain cell homeostasis, whereas deficient mitophagy accelerates the accumulation of damaged mitochondria to mediate the pathologies of NDDs. Therefore, targeting mitophagy has become a valuable therapeutic pathway for the treatment of NDDs. Several mitophagy modulators have been shown to ameliorate neurodegeneration in PD and AD. However, it remains to be further investigated for other NDDs. Here, we describe the mechanism and key signaling pathway of mitophagy and summarize the roles of defective mitophagy on the pathogenesis of NDDs. Further, we underline the development advances of mitophagy modulators for PD and AD therapy, discuss the therapeutic challenges and limitations of the existing modulators, and provide guidelines for mitophagy mechanism exploration and drug design.

BOK-engaged mitophagy alleviates neuropathology in Alzheimer's disease

Mitochondrial malfunction associated with impaired mitochondrial quality control and self-renewal machinery, known as mitophagy, is an under-appreciated mechanism precipitating synaptic loss and cognitive impairments in Alzheimer's disease. Promoting mitophagy has been shown to improve cognitive function in Alzheimer's disease animals. However, the regulatory mechanism was unclear, which formed the aim of this study. Here, we found that a neuron-specific loss of Bcl-2 family member BOK in patients with Alzheimer's disease and APPswe/PS1dE9 (APP/PS1) mice is closely associated with mitochondrial damage and mitophagy defects. We further revealed that BOK is the key to the Parkin-mediated mitophagy through competitive binding to the MCL1/Parkin complex, resulting in Parkin release and translocation to damaged mitochondria to initiate mitophagy. Furthermore, overexpressing bok in hippocampal neurons of APP/PS1 mice alleviated mitophagy and mitochondrial malfunction, resulting in improved cognitive function. Conversely, the knockdown of bok worsened the aforementioned Alzheimer's disease-related changes. Our findings uncover a novel mechanism of BOK signalling through regulating Parkin-mediated mitophagy to mitigate amyloid pathology, mitochondrial and synaptic malfunctions, and cognitive decline in Alzheimer's disease, thus representing a promising therapeutic target.

Targeting NLRP3 Inflammasomes: A Trojan Horse Strategy for Intervention in Neurological Disorders

Recently, a growing focus has been on identifying critical mechanisms in neurological diseases that trigger a cascade of events, making it easier to target them effectively. One such mechanism is the inflammasome, an essential component of the immune response system that plays a crucial role in disease progression. The NLRP3 (nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3) inflammasome is a subcellular multiprotein complex that is widely expressed in the central nervous system (CNS) and can be activated by a variety of external and internal stimuli. When activated, the NLRP3 inflammasome triggers the production of proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18) and facilitates rapid cell death by assembling the inflammasome. These cytokines initiate inflammatory responses through various downstream signaling pathways, leading to damage to neurons. Therefore, the NLRP3 inflammasome is considered a significant contributor to the development of neuroinflammation. To counter the damage caused by NLRP3 inflammasome activation, researchers have investigated various interventions such as small molecules, antibodies, and cellular and gene therapy to regulate inflammasome activity. For instance, recent studies indicate that substances like micro-RNAs (e.g., miR-29c and mR-190) and drugs such as melatonin can reduce neuronal damage and suppress neuroinflammation through NLRP3. Furthermore, the transplantation of bone marrow mesenchymal stem cells resulted in a significant reduction in the levels of pyroptosis-related proteins NLRP3, caspase-1, IL-1β, and IL-18. However, it would benefit future research to have an in-depth review of the pharmacological and biological interventions targeting inflammasome activity. Therefore, our review of current evidence demonstrates that targeting NLRP3 inflammasomes could be a pivotal approach for intervention in neurological disorders.

Mechanisms by which microbiome-derived metabolites exert their impacts on neurodegeneration

Recent developments in microbiome research suggest that the gut microbiome may remotely modulate central and peripheral neuronal processes, ranging from early brain development to age-related changes. Dysbiotic microbiome configurations have been increasingly associated with neurological disorders, such as neurodegeneration, but causal understanding of these associations remains limited. Most mechanisms explaining how the microbiome may induce such remote neuronal effects involve microbially modulated metabolites that influx into the 'sterile' host. Some metabolites are able to cross the blood-brain barrier (BBB) to reach the central nervous system, where they can impact a variety of cells and processes. Alternatively, metabolites may directly signal to peripheral nerves to act as neurotransmitters or exert modulatory functions, or impact immune responses, which, in turn, modulate neuronal function and associated disease propensity. Herein, we review the current knowledge highlighting microbiome-modulated metabolite impacts on neuronal disease, while discussing unknowns, controversies and prospects impacting this rapidly evolving research field.

Ellagic acid alleviates DSS-induced ulcerative colitis by inhibiting ROS/NLRP3 pathway activation and modulating gut microbiota in mice

Ulcerative colitis (UC) can cause severe oxidative stress in the colon, which can lead to tissue damage and an imbalance in the normal gut microbiota. Ellagic acid (EA) is one of the main types of plant polyphenols with improved pharmacological effects such as antioxidant, anti-inflammatory, and antibacterial properties. However, currently, the studies on the impact of EA on the gut microbiota and its potential to alleviate UC in mice through the ROS/NLRP3 pathway are limited. In this study, dextran sodium sulfate (DSS) was used to construct a UC mouse model, which was then treated with EA as an intervention for UC. The results revealed that EA alleviated the trend of liver, spleen, and weight changes in UC mice and improved colon oxidative stress, inflammation, and pathological damage. Mechanistically, DSS-induced UC indicated a significant increase in ROS/NLRP3 pathway-related factors, whereas EA intervention activated the Nrf2 pathway to reduce these factors. Furthermore, the DSS group had a reduced abundance of Firmicutes (59.02%) and an increased abundance of Bacteroides and Proteobacterium by 1.8 times and 10.16%; however, EA intervention reversed these changes, thus alleviating UC. The findings of this study revealed that EA could significantly enhance the composition of gut microbiota in UC and reduce the inflammatory response, colonic damage as well as oxidative stress caused by DSS by regulating the ROS/NLRP3 pathway. These results provide novel perspectives on the prevention and treatment strategies of UC and highlight the therapeutic benefits of EA in managing colitis.

Preclinical and clinical study on type 3 metabotropic glutamate receptors in Parkinson's disease

Metabotropic glutamate (mGlu) receptors are candidate drug targets for therapeutic intervention in Parkinson's disease (PD). Here we focused on mGlu3, a receptor subtype involved in synaptic regulation and neuroinflammation. mGlu3-/- mice showed an enhanced nigro-striatal damage and microglial activation in response to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Expression of genes encoding anti-inflammatory proteins and neuroprotective factors was reduced in the striatum of MPTP-treated mGlu3-/- mice. We also examined polymorphic variants of GRM3 (the mGlu3 receptor encoding gene) in 723 PD patients and 826 healthy controls. Two GRM3 haplotypes were associated with PD, and gene variants correlated with motor and non-motor signs. Interestingly, PD patients carrying each of the two haplotypes showed an impaired cortical plasticity in the paired associated stimulation paradigm of magnetic transcranial stimulation. These findings suggest that mGlu3 receptors are neuroprotective in mouse models of parkinsonism and shape mechanisms of cortical plasticity in PD.

Molecular Symphony of Mitophagy: Ubiquitin-Specific Protease-30 as a Maestro for Precision Management of Neurodegenerative Diseases

INTRODUCTION

Mitochondrial dysfunction stands as a pivotal feature in neurodegenerative disorders, spurring the quest for targeted therapeutic interventions. This review examines Ubiquitin-Specific Protease 30 (USP30) as a master regulator of mitophagy with therapeutic promise in Alzheimer's disease (AD) and Parkinson's disease (PD). USP30's orchestration of mitophagy pathways, encompassing PINK1-dependent and PINK1-independent mechanisms, forms the crux of this exploration.

METHOD

A systematic literature search was conducted in PubMed, Scopus, and Web of Science, selecting studies that investigated USP's function, inhibitor design, or therapeutic efficacy in AD and PD. Inclusion criteria encompassed mechanistic and preclinical/clinical data, while irrelevant or duplicate references were excluded. Extracted findings were synthesized narratively.

RESULTS

USP30 modulates interactions with translocase of outer mitochondrial membrane (TOM) 20, mitochondrial E3 ubiquitin protein ligase 1 (MUL1), and Parkin, thus harmonizing mitochondrial quality control. Emerging novel USP30 inhibitors, racemic phenylalanine derivatives, N-cyano pyrrolidine, and notably, benzosulphonamide class compounds, restore mitophagy, and reduce neurodegenerative phenotypes across diverse models with minimal off-target effects. Modulation of other USPs also influences neurodegenerative disease pathways, offering additional therapeutic avenues.

CONCLUSIONS

In highlighting the nuanced regulation of mitophagy by USP30, this work heralds a shift toward more precise and effective treatments, paving the way for a new era in the clinical management of neurodegenerative disorders.

Mitophagy in ischemic heart disease: molecular mechanisms and clinical management

The influence of the mitochondrial control system on ischemic heart disease has become a major focus of current research. Mitophagy, as a very crucial part of the mitochondrial control system, plays a special role in ischemic heart disease, unlike mitochondrial dynamics. The published reviews have not explored in detail the unique function of mitophagy in ischemic heart disease, therefore, the aim of this paper is to summarize how mitophagy regulates the progression of ischemic heart disease. We conclude that mitophagy affects ischemic heart disease by promoting cardiomyocyte hypertrophy and fibrosis, the progression of oxidative stress, the development of inflammation, and cardiomyocyte death, and that the specific mechanisms of mitophagy are worthy of further investigation.

YAP1 exacerbates pyroptosis and senescence in nucleus pulposus cells by promoting BNIP3-mediated mitophagy

Yes-associated protein 1 (YAP1) is a crucial downstream effector of the Hippo pathway that plays a role in regulating inflammation and mitochondrial function. However, whether YAP1 regulates pyroptosis in nucleus pulposus (NP) cells caused by inflammation via mitophagy remains unclear. This study aimed to investigate the effects of YAP1 on the pyroptosis of NP cells induced by LPS. Here, we demonstrated that the protein expression of YAP1 in the NP tissue of degenerative discs was significantly reduced. Next, we found that NLRP3 inflammasome activation in YAP1-overexpressing (YAP1-ov) NP cells was further enhanced in the LPS-induced inflammatory microenvironment. YAP1-ov strongly aggravated inflammation-induced pyroptosis and senescence, but these effects were reversed by the inhibition of BNIP3-mediated mitophagy. However, comparative analysis of the overexpression of YAP1 in normal discs and discs after annulus fibrosus puncture revealed that YAP1-ov accelerated the degeneration of normal discs and attenuated the degeneration of annulus fibrosus punctured discs in vivo. Additionally, YAP1-ov upregulated the expression of TNFAIP3, an anti-inflammatory protective protein, and CLPP, a vital protein in the mitochondrial unfolded protein response, in NP cells. Collectively, the above results revealed that YAP1 exacerbates LPS-induced pyroptosis and senescence of NP cells by promoting BNIP3-mediated mitophagy, which causes disc degeneration. Notably, YAP1-ov mitigated the degeneration of the disc caused by annular needle puncture in vivo, suggesting its potential as a therapeutic candidate foracute IDD injury.

Inter- and intracellular mitochondrial communication: signaling hubs in aging and age-related diseases

Mitochondria are versatile and complex organelles that can continuously communicate and interact with the cellular milieu. Deregulated communication between mitochondria and host cells/organelles has significant consequences and is an underlying factor of many pathophysiological conditions, including the process of aging. During aging, mitochondria lose function, and mitocellular communication pathways break down; mitochondrial dysfunction interacts with mitochondrial dyscommunication, forming a vicious circle. Therefore, strategies to protect mitochondrial function and promote effective communication of mitochondria can increase healthy lifespan and longevity, which might be a new treatment paradigm for age-related disorders. In this review, we comprehensively discuss the signal transduction mechanisms of inter- and intracellular mitochondrial communication, as well as the interactions between mitochondrial communication and the hallmarks of aging. This review emphasizes the indispensable position of inter- and intracellular mitochondrial communication in the aging process of organisms, which is crucial as the cellular signaling hubs. In addition, we also specifically focus on the status of mitochondria-targeted interventions to provide potential therapeutic targets for age-related diseases.

Hidden role of microglia during neurodegenerative disorders and neurocritical care: A mitochondrial perspective

The incidence of aging-related neurodegenerative disorders and neurocritical care diseases is increasing worldwide. Microglia, the main inflammatory cells in the brain, could be potential viable therapeutic targets for treating neurological diseases. Interestingly, mitochondrial functions, including energy metabolism, mitophagy and transfer, fission and fusion, and mitochondrial DNA expression, also change in activated microglia. Notably, mitochondria play an active and important role in the pathophysiology of neurodegenerative disorders and neurocritical care diseases. This review briefly summarizes the current knowledge on mitochondrial dysfunction in microglia in neurodegenerative disorders and neurocritical care diseases and comprehensively discusses the prospects of the application of neurological injury prevention and treatment targets by mitochondria.

Cycloastragenol reduces microglial NLRP3 inflammasome activation in Parkinson's disease models by promoting autophagy and reducing Scrib-driven ROS

BACKGROUND

In Parkinson's disease (PD), microglial autophagy is crucial for the maintenance of cellular redox homeostasis. Meanwhile, cycloastragenol (CAG), a triterpenoid saponin and the principal active component of Astragalus, reduces the activation of NLRP3 inflammasomes. Nevertheless, the specific molecular mechanisms underlying the CAG-mitigated microglial neuroinflammation remains obscure in PD.

PURPOSE

This study explored the role of CAG in the activation of microglial NLRP3 inflammasome and the mechanisms underlying its therapeutic potential for PD treatment.

STUDY DESIGN

The effect of CAG was assessed in α-Syn-induced primary microglia and PD models.

METHODS

AAV1/2-hsyn-SNCA (A53T) was stereo-injected into the striatum of mice to induce PD models and CAG was orally administered. The mice underwent quantitative 4D proteomics analysis and behavioral assessments. The primary microglia and neuron cultures were analyzed by western blotting, immunofluorescence, transmission electron microscopy, etc. RESULTS: CAG reduced phagocytosis-induced reactive oxygen species (ROS) by suppressing the microglial Scribble (Scrib) and p22phox expression. Concurrently, CAG enhanced autophagy, promoted α-Syn clearance, and reduced mitochondrial damage. These synergistic effects downregulated NLRP3 inflammasome activation, in turn reducing gasdermin D cleavage, caspase-1 activation, and the release of interleukin-1β and interleukin-18. Further investigation revealed that CAG shielded neurons from α-Syn toxicity, thus attenuating behavioral impairments observed in the mouse PD model.

CONCLUSION

CAG mitigates neuroinflammation by inhibiting ROS-induced NLRP3 inflammasome activation in microglia via promoting microglial autophagy and reducing the activity of Scrib-associated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which signifies a promising alternative approach to PD management.

Therapeutic potential of Parkin and its regulation in Parkinson's disease

Parkinson's disease (PD) is a debilitating neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the midbrain substantia nigra, resulting in motor and non-motor symptoms. While the exact etiology of PD remains elusive, a growing body of evidence suggests that dysfunction in the parkin protein plays a pivotal role in the pathogenesis of the disease. Parkin is an E3 ubiquitin ligase that ubiquitinates substrate proteins to control a number of crucial cellular processes including protein catabolism, immune response, and cellular apoptosis.While autosomal recessive mutations in the PARK2 gene, which codes for parkin, are linked to an inherited form of early-onset PD, heterozygous mutations in PARK2 have also been reported in the more commonly occurring sporadic PD cases. Impairment of parkin's E3 ligase activity is believed to play a pathogenic role in both familial and sporadic forms of PD.This article provides an overview of the current understanding of the mechanistic basis of parkin's E3 ligase activity, its major physiological role in controlling cellular functions, and how these are disrupted in familial and sporadic PD. The second half of the manuscript explores the currently available and potential therapeutic strategies targeting parkin structure and/or function in order to slow down or mitigate the progressive neurodegeneration in PD.

Effect of bioactive extracts from Eucalyptus globulus leaves in experimental models of Alzheimer's disease

Current therapies for Alzheimer's disease (AD) do not delay its progression, therefore, novel disease-modifying strategies are urgently needed. Recently, an increasing number of compounds from natural origin with protective properties against AD have been identified. Mixtures or extracts obtained from natural products containing several bioactive compounds have multifunctional properties and have drawn the attention because multiple AD pathways can be simultaneously modulated. This study evaluated the in vitro and in vivo effect of the essential oil (EO) obtained from the hydrodistillation of Eucalyptus globulus leaves, and an extract obtained from the hydrodistillation residual water (HRW). It was observed that EO and HRW have anti-inflammatory effect in brain immune cells modeling AD, namely lipopolysaccharide (LPS)- and amyloid-beta (Aβ)-stimulated microglia. In cell models that mimic AD-related neuronal dysfunction, HRW attenuated Aβ secretion and Aβ-induced mitochondrial dysfunction. Since the HRW's major components did not cross the blood-brain barrier, both EO and HRW were administered to the APP/PS1 transgenic AD mouse model by an intranasal route, which reduced cortical and hippocampal Aβ levels, and to rescue memory deficits and anxiety-like behaviors. Finally, HRW and EO were found to regulate cholesterol levels in aged mice after intranasal administration, suggesting that these extracts can reduce hypercholesterolemia and avoid risk for AD development. Overall, findings support a protective role of E. globulus extracts against AD‑like pathology and cognitive impairment highlighting the underlying mechanisms. These extracts obtained from underused forest biomass could be useful to develop nutraceutical supplements helpful to avoid AD risk and to prevent its progression.

Urolithin A Protects Hepatocytes from Palmitic Acid-Induced ER Stress by Regulating Calcium Homeostasis in the MAM

An ellagitannin-derived metabolite, Urolithin A (UA), has emerged as a potential therapeutic agent for metabolic disorders due to its antioxidant, anti-inflammatory, and mitochondrial function-improving properties, but its efficacy in protecting against ER stress remains underexplored. The endoplasmic reticulum (ER) is a cellular organelle involved in protein folding, lipid synthesis, and calcium regulation. Perturbations in these functions can lead to ER stress, which contributes to the development and progression of metabolic disorders such as metabolic-associated fatty liver disease (MAFLD). In this study, we identified a novel target protein of UA and elucidated its mechanism for alleviating palmitic acid (PA)-induced ER stress. Cellular thermal shift assay (CETSA)-LC-MS/MS analysis revealed that UA binds directly to the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA), an important regulator of calcium homeostasis in mitochondria-associated ER membranes (MAMs). As an agonist of SERCA, UA attenuates abnormal calcium fluctuations and ER stress in PA-treated liver cells, thereby contributing to cell survival. The lack of UA activity in SERCA knockdown cells suggests that UA regulates cellular homeostasis through its interaction with SERCA. Collectively, our results demonstrate that UA protects against PA-induced ER stress and enhances cell survival by regulating calcium homeostasis in MAMs through SERCA. This study highlights the potential of UA as a therapeutic agent for metabolic disorders associated with ER stress.

Advanced Spray-Dried Inhalable Microparticles/Nanoparticles of an Innovative Mitophagy Activator for Targeted Lung Delivery: Design, Comprehensive Characterization, Human Lung Cell Culture, and In Vitro Aerosol Dispersion Performance

Urolithin A (UA) has demonstrated the ability to stimulate mitophagy and enhance mitochondrial and cellular health in skeletal muscles in humans after oral administration. It is hypothesized that targeted delivery of UA as inhaled dry powders to the lungs will enhance mitochondrial health through mitochondrial biogenesis. This study aimed to engineer inhalable excipient-free powders of UA as dry powder inhalers (DPIs) for targeted pulmonary delivery. The particles were designed by particle engineering from dilute organic solutions of UA using the state-of-the-art spray drying technology in a closed mode. Comprehensive physicochemical characterization and advanced microscopy techniques were conducted to examine phase behavior, molecular properties, and particle properties, which are necessary for the rational design of advanced pulmonary inhalation aerosols. Molecular fingerprinting was conducted by using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and Raman spectroscopy. Chemical imaging and mapping were conducted using confocal Raman microscopy (CRM) and IR microscopy. The advanced spray-dried (SD) excipient-free powders were successfully produced at different spraying pump feed rates and exhibited favorable molecular and particle properties. The excipient-free SD powders exhibited outstanding in vitro aerosol dispersion performance with an FDI-approved human DPI device (Neohaler) and correlated with the spray drying pump rate. In vitro, cell viability of various human pulmonary cells from different lung regions demonstrated biocompatibility and safety at different doses of UA. The transepithelial electrical resistance (TEER) assay shows that UA maintains cell membrane integrity and barrier tightness, indicating its potential for safe and effective localized drug delivery without long-term adverse effects. These results demonstrated that UA has favorable physicochemical and in vitro properties for inhalation and can be successfully engineered into excipient-free inhalable microparticles/nanoparticles as DPIs.

Coumarins as versatile therapeutic phytomolecules: A systematic review

BACKGROUND

Coumarins, abundantly distributed in a plethora of biologically active compounds, serve as a fundamental motif in numerous natural products, drugs, and therapeutic leads. Despite their small size, they exhibit a diverse range of biological activities, intriguing researchers with their immense pharmacological potential.

PURPOSE

This study consolidates the evidence regarding the essential role of coumarins in modern drug discovery, exploring their broad-spectrum pharmaceutical effects, structural versatility, and mechanisms of action across various domains.

METHODS

For literature search, we utilized PubMed, Google scholar, and SciFinder databases. Keyword and keyword combinations such as "coumarins", "natural coumarins", "specific natural coumarins for particular diseases", and "therapeutic effects" were employed to retrieve relevant studies. The search encompassed articles published between 2005 and 2023. Selection criteria included studies reporting on the pharmacological activities of natural coumarins against various diseases.

RESULTS

The results highlight the therapeutic potential of natural coumarins against various diseases, demonstrating anti-cancer, anti-oxidant, and anti-inflammatory activities. They also act as monoamine oxidase inhibitors and phosphodiesterase inhibitors, and as anti-thrombotic, anti-diabetic, and hepatoprotective agents. They also show efficacy against diabetic nephropathy, neurodegenerative diseases, microbial infections and many other diseases.

CONCLUSION

This review underscores the significant role of natural coumarins in medicinal chemistry and drug discovery. Their diverse biological activities and structural versatility make them promising therapeutic agents. This study serves as a catalyst for further research in the field, aiming to address emerging challenges and opportunities in drug development.

Targeting selective autophagy in CNS disorders by small-molecule compounds

Autophagy functions as the primary cellular mechanism for clearing unwanted intracellular contents. Emerging evidence suggests that the selective elimination of intracellular organelles through autophagy, compared to the increased bulk autophagic flux, is crucial for the pathological progression of central nervous system (CNS) disorders. Notably, autophagic removal of mitochondria, known as mitophagy, is well-understood in an unhealthy brain. Accumulated data indicate that selective autophagy of other substrates, including protein aggregates, liposomes, and endoplasmic reticulum, plays distinctive roles in various pathological stages. Despite variations in substrates, the molecular mechanisms governing selective autophagy can be broadly categorized into two types: ubiquitin-dependent and -independent pathways, both of which can be subjected to regulation by small-molecule compounds. Notably, natural products provide the remarkable possibility for future structural optimization to regulate the highly selective autophagic clearance of diverse substrates. In this context, we emphasize the selectivity of autophagy in regulating CNS disorders and provide an overview of chemical compounds capable of modulating selective autophagy in these disorders, along with the underlying mechanisms. Further exploration of the functions of these compounds will in turn advance our understanding of autophagic contributions to brain disorders and illuminate precise therapeutic strategies for these diseases.

Urolithin A alleviates cell senescence by inhibiting ferroptosis and enhances corneal epithelial wound healing

Purpose

To analyze the therapeutic effect and mechanism of Urolithin A (UA) on delayed corneal epithelial wound healing.

Methods

The C57BL/6 mice were continuously exposed to hyperosmotic stress (HS) for 7 days followed by the removal of central corneal epithelium to establish a delayed corneal epithelial wound healing model in vivo. In vitro, the human corneal epithelial cell line (HCE-T) was also incubated under HS. UA was administered in vivo and in vitro to study its effects on corneal epithelial cells. Senescence-associated β-galactosidase (SA-β-gal) staining was performed to detect the level of cell senescence. Transcriptome sequencing (RNA-seq) was conducted to elucidate the molecular mechanism underlying the effect of UA on corneal epithelial repair. Additionally, the expression of senescence-related and ferroptosis-related genes and the levels of lipid peroxides (LPO) and malondialdehyde (MDA) were measured.

Results

Hyperosmotic stress (HS) significantly increased the proportion of SA-β-gal staining positive cells in corneal epithelial cells and upregulated the expression of p16 and p21 (p < 0.0001). Topical application of UA decreased the accumulation of senescent cells in corneal epithelial wounds and promoted epithelial wound healing. The results of RNA-seq of HS-induced corneal epithelial cells showed that the ferroptosis pathway was significantly dysregulated. Further investigation revealed that UA decreased the level of oxidative stress in HCE-T cells, including the levels of LPO and MDA (p < 0.05). Inhibition of ferroptosis significantly prevented cellular senescence in HS-induced HCE-T cells.

Conclusion

In this study, UA promoted HS-induced delayed epithelial wound healing by reducing the senescence of corneal epithelial cells through the inhibition of ferroptosis.

Mitophagy and cGAS-STING crosstalk in neuroinflammation

Mitophagy, essential for mitochondrial health, selectively degrades damaged mitochondria. It is intricately linked to the cGAS-STING pathway, which is crucial for innate immunity. This pathway responds to mitochondrial DNA and is associated with cellular stress response. Our review explores the molecular details and regulatory mechanisms of mitophagy and the cGAS-STING pathway. We critically evaluate the literature demonstrating how dysfunctional mitophagy leads to neuroinflammatory conditions, primarily through the accumulation of damaged mitochondria, which activates the cGAS-STING pathway. This activation prompts the production of pro-inflammatory cytokines, exacerbating neuroinflammation. This review emphasizes the interaction between mitophagy and the cGAS-STING pathways. Effective mitophagy may suppress the cGAS-STING pathway, offering protection against neuroinflammation. Conversely, impaired mitophagy may activate the cGAS-STING pathway, leading to chronic neuroinflammation. Additionally, we explored how this interaction influences neurodegenerative disorders, suggesting a common mechanism underlying these diseases. In conclusion, there is a need for additional targeted research to unravel the complexities of mitophagy-cGAS-STING interactions and their role in neurodegeneration. This review highlights potential therapies targeting these pathways, potentially leading to new treatments for neuroinflammatory and neurodegenerative conditions. This synthesis enhances our understanding of the cellular and molecular foundations of neuroinflammation and opens new therapeutic avenues for neurodegenerative disease research.

The Potential of Metabolomics to Find Proper Biomarkers for Addressing the Neuroprotective Efficacy of Drugs Aimed at Delaying Parkinson's and Alzheimer's Disease Progression

The first objective is to highlight the lack of tools to measure whether a given intervention affords neuroprotection in patients with Alzheimer's or Parkinson's diseases. A second aim is to present the primary outcome measures used in clinical trials in cohorts of patients with neurodegenerative diseases. The final aim is to discuss whether metabolomics using body fluids may lead to the discovery of biomarkers of neuroprotection. Information on the primary outcome measures in clinical trials related to Alzheimer's and Parkinson's disease registered since 2018 was collected. We analysed the type of measures selected to assess efficacy, not in terms of neuroprotection since, as stated in the aims, there is not yet any marker of neuroprotection. Proteomic approaches using plasma or CSF have been proposed. PET could estimate the extent of lesions, but disease progression does not necessarily correlate with a change in tracer uptake. We propose some alternatives based on considering the metabolome. A new opportunity opens with metabolomics because there have been impressive technological advances that allow the detection, among others, of metabolites related to mitochondrial function and mitochondrial structure in serum and/or cerebrospinal fluid; some of the differentially concentrated metabolites can become reliable biomarkers of neuroprotection.

Urolithin A suppresses NLRP3 inflammasome activation by inhibiting the generation of reactive oxygen species and prevents monosodium urate crystal-induced peritonitis

The NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome triggers the maturation of interleukin-1β (IL-1β) and is implicated in the pathogenesis of various inflammatory diseases. Urolithin A, a gut microbial metabolite of ellagic acid, reportedly exerts antiinflammatory effects in vitro and in vivo. However, whether urolithin A suppresses NLRP3 inflammasome activation is unclear. In this study, urolithin A inhibited the cleavage of NLRP3 inflammasome agonist-induced caspase-1, maturation of IL-1β, and activation of pyroptosis in lipopolysaccharide-primed mouse bone marrow-derived macrophages. Urolithin A reduced generation of intracellular and mitochondrial reactive oxygen species (ROS) and restricted the interaction between thioredoxin-interacting protein and NLRP3, which attenuated NLRP3 inflammasome activation. Urolithin A administration prevented monosodium urate-induced peritonitis in mice. Collectively, these findings indicate that urolithin A suppresses NLRP3 inflammasome activation, at least partially, by repressing the generation of intracellular and mitochondrial ROS.

Ameliorating Mitochondrial Dysfunction for the Therapy of Parkinson's Disease

Parkinson's disease (PD) is currently the second most incurable central neurodegenerative disease resulting from various pathogenesis. As the "energy factory" of cells, mitochondria play an extremely important role in supporting neuronal signal transmission and other physiological activities. Mitochondrial dysfunction can cause and accelerate the occurrence and progression of PD. How to effectively prevent and suppress mitochondrial disorders is a key strategy for the treatment of PD from the root. Therefore, the emerging mitochondria-targeted therapy has attracted considerable interest. Herein, the relationship between mitochondrial dysfunction and PD, the causes and results of mitochondrial dysfunction, and major strategies for ameliorating mitochondrial dysfunction to treat PD are systematically reviewed. The study also prospects the main challenges for the treatment of PD.

CDK5-USP30 signaling pathway regulates MAVS-mediated inflammation via suppressing mitophagy in MPTP/MPP+ PD model

The discovery of MPTP, an industrial chemical and contaminant of illicit narcotics, which causes parkinsonism in humans, non-human primates and rodents, has led to environmental pollutants exposure being convicted as key candidate in Parkinson's disease (PD) pathogenesis. Though MPTP-induced mitochondrial dysfunction and neuroinflammation are mainly responsible for the causative issue of MPTP neurotoxicity, the underlying mechanism involved remains unclear. Here, we reveal a novel signaling mechanism of CDK5-USP30-MAVS regulating MPTP/MPP+ induced PD. MPP+ (the toxic metabolite of MPTP) treatment not only led to the increased protein levels of USP30 but also to mitophagy inhibition, mitochondrial dysfunction, and MAVS-mediated inflammation in BV2 microglial cells. Both mitophagy stimulation (Urolithin A administration) and USP30 knockdown relieved MAVS-mediated inflammation via restoring mitophagy and mitochondrial function in MPP+-induced cell model. Notably, MPTP/MPP+-induced CDK5 activation regulated USP30 phosphorylation at serine 216 to stabilize USP30. Moreover, CDK5-USP30 pathway promoted MAVS-mediated inflammation in MPTP/MPP+-induced PD model. Inhibition of CDK5 not only had a protective effect on MPP+-induced cell model of PD via suppressing the upregulation of USP30 and the activation of MAVS inflammation pathway in vitro, but also prevented neurodegeneration in vivo and alleviated movement impairment in MPTP mouse model of PD. Overall, our study reveal that CDK5 blocks mitophagy through phosphorylating USP30 and activates MAVS inflammation pathway in MPTP/MPP+-induced PD model, which suggests that CDK5-USP30-MAVS signaling pathway represents a valuable treatment strategy for PD induced by environmental neurotoxic pollutants in relation to MPTP.

Effects of Strigolactones on NLRP3 Activation, Nitrosative Stress, and Antioxidant Mox Phenotype: In Vitro and In Silico Evidence

Phytohormones have significant roles in redox metabolism, inflammatory responses, and cellular survival mechanisms within the microenvironment of the mammalian brain. Herein, we identified the mammalian molecular targets of three representative strigolactone (SL) analogues structurally derived from apocarotenoids and the functional equivalent of plant hormones. All tested SL analogues have an inhibitory effect on NLRP3 inflammasome-mediated IL-1β release in murine microglial cells. However, IND and EGO10 became prominent among them due to their high potency at low micromolar doses. All SL analogues dose-dependently suppressed the release and expression of proinflammatory factors. For EGO10 and IND, IC50 values for iNOS-associated NO secretion were as low as 1.72 and 1.02 μM, respectively. In silico analyses revealed that (S)-EGO10 interacted with iNOS, NLRP3, and Keap1 ligands with the highest binding affinities among all stereoisomeric SL analogues. Although all compounds were effective in microglial Mox phenotype polarization, 4-Br-debranone exhibited a differential pattern for upregulating Nrf2-driven downstream enzymes.

Modulatory Effects of Phytochemicals on Gut-Brain Axis: Therapeutic Implication

This article explores the potential therapeutic implications of phytochemicals on the gut-brain axis (GBA), which serves as a communication network between the central nervous system and the enteric nervous system. Phytochemicals, which are compounds derived from plants, have been shown to interact with the gut microbiota, immune system, and neurotransmitter systems, thereby influencing brain function. Phytochemicals such as polyphenols, carotenoids, flavonoids, and terpenoids have been identified as having potential therapeutic implications for various neurological disorders. The GBA plays a critical role in the development and progression of various neurological disorders, including Parkinson's disease, multiple sclerosis, depression, anxiety, and autism spectrum disorders. Dysbiosis, or an imbalance in gut microbiota composition, has been associated with a range of neurological disorders, suggesting that modulating the gut microbiota may have potential therapeutic implications for these conditions. Although these findings are promising, further research is needed to elucidate the optimal use of phytochemicals in neurological disorder treatment, as well as their potential interactions with other medications. The literature review search was conducted using predefined search terms such as phytochemicals, gut-brain axis, neurodegenerative, and Parkinson in PubMed, Embase, and the Cochrane library.

Gut microbiota-generated metabolites: missing puzzles to hosts' health, diseases, and aging

The gut microbiota, an intricate community of bacteria residing in the gastrointestinal system, assumes a pivotal role in various physiological processes. Beyond its function in food breakdown and nutrient absorption, gut microbiota exerts a profound influence on immune and metabolic modulation by producing diverse gut microbiota-generated metabolites (GMGMs). These small molecules hold potential to impact host health via multiple pathways, which exhibit remarkable diversity, and have gained increasing attention in recent studies. Here, we elucidate the intricate implications and significant impacts of four specific metabolites, Urolithin A (UA), equol, Trimethylamine N-oxide (TMAO), and imidazole propionate, in shaping human health. Meanwhile, we also look into the advanced research on GMGMs, which demonstrate promising curative effects and hold great potential for further clinical therapies. Notably, the emergence of positive outcomes from clinical trials involving GMGMs, typified by UA, emphasizes their promising prospects in the pursuit of improved health and longevity. Collectively, the multifaceted impacts of GMGMs present intriguing avenues for future research and therapeutic interventions. [BMB Reports 2024; 57(5): 207-215].

ApoE4 dysregulation incites depressive symptoms and mitochondrial impairments in mice

Apolipoprotein E4 (ApoE4) is involved in the stress-response processes and is hypothesized to be a risk factor for depression by means of mitochondrial dysfunction. However, their exact roles and underlying mechanisms are largely unknown. ApoE4 transgenic mice (B6. Cg-ApoEtm1Unc Cdh18Tg( GFAP-APOE i4)1Hol /J) were subjected to stress (lipopolysaccharides, LPS) to elucidate the aetiology of ApoE4-induced depression. LPS treatment significantly aggravated depression-like behaviours, concurrent with neuroinflammation and impaired mitochondrial changes, and melatonin/Urolithin A (UA) + 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) reversed these effects in ApoE4 mice. Concurrently, ApoE4 mice exhibited mitophagy deficits, which could be further exacerbated by LPS stimulation, as demonstrated by reduced Atg5, Beclin-1 and Parkin levels, while PINK1 levels were increased. However, these changes were reversed by melatonin treatment. Additionally, proteomic profiling suggested mitochondria-related signalling and network changes in ApoE4 mice, which may underlie the exaggerated response to LPS. Furthermore, HEK 293T cells transfected with ApoE4 showed mitochondria-associated protein and mitophagy defects, including PGC-1α, TFAM, p-AMPKα, PINK1 and LC3B impairments. Additionally, it aggravates mitochondrial impairment (particularly mitophagy), which can be attenuated by triggering autophagy. Collectively, ApoE4 dysregulation enhanced depressive behaviour upon LPS stimulation.

Intestinal metabolite UroB alleviates cerebral ischemia/reperfusion injury by promoting competition between TRIM65 and TXNIP for binding to NLRP3 inflammasome in response to neuroinflammation

Our previous research suggests that targeting NLRP3 inflammasomes holds promise for mitigating cerebral ischemia/reperfusion injury. The gut metabolite Urolithin B (UroB) has been shown to inhibit the neuroinflammation. However, the specific role of UroB in cerebral ischemia/reperfusion injury and its potential impact on NLRP3 inflammasome remain unclear. In this study, acute stroke was simulated using the MCAO model in male Sprague-Dawley rats. UroB was intraperitoneally administered after 1 h of reperfusion. The effects of UroB on brain tissue were evaluated, including infarct volume, brain edema, and neurobehavioral changes. Western blotting and immunofluorescence were performed to investigate the effect of UroB on inflammation-related proteins. Furthermore, TRIM65 knockdown and TXNIP overexpression experiments elucidated the role of UroB in NLRP3 inflammasome activation. The ( demonstrate the neuroprotective effect of UroB in acute stroke, reducing brain tissue damage and improving motor function. Mechanistically, UroB modulated neuroinflammation by influencing TXNIP and TRIM65 protein expression, as well as competitive binding to the NLRP3 inflammasome, attenuating cerebral ischemia/reperfusion injury. In conclusion, the potential of UroB as a protective agent against cerebral ischemia/reperfusion injury in acute stroke stands out as it regulates TRIM65 and TXNIP competitive binding to the NLRP3 inflammasome. These findings suggest that UroB is a promising drug candidate for the treatment of acute stroke.

The effects of urolithin A on poly I:C-induced microglial activation

Neuroinflammation can be triggered by various stimuli, including viral infections. Viruses can directly invade the brain and infect neuronal cells or indirectly trigger a "cytokine storm" in the periphery that eventually leads to microglial activation in the brain. While this initial activation of microglial cells is important for viral clearance, chronic activation leads to excessive inflammation and oxidative stress, which can be neurotoxic. Remarkebly, recent studies have shown that certain viruses such as influenza A virus, coronavirus, herpes virus and Epstein-Barr virus may be involved in the development of neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Therefore, it is important to find therapeutic strategies against chronic neuroinflammation triggered by viral infections. Here, we investigated the effects of urolithin A (UA) on microglial activation in vitro induced by a viral mimetic, poly I:C, in a triple co-culture system of neurons, astrocytes and microglial cells. Immunocytochemistry was used to perform a comprehensive single-cell analysis of the morphological changes of microglia as an indicator of their reactive state. Treatment with UA significantly prevented the poly I:C-induced reactive state of microglia, which was characterized by increased expression of the microglial activation markers CD68 and IBA-1. UA restored the poly I:C-induced morphology by restoring microglial ramification. In addition, UA was able to reduce the release of the pro-inflammatory mediators CCL2, TNF-α, and IL-1β and showed a trend toward attenuation of cellular ROS production in poly I:C-treated cultures. Overall, this study suggests that UA as a component of a healthy diet may help prevent virus-induced neuroinflammation and may have therapeutic potential for future studies to prevent or treat neurodegenerative diseases by targeting the associated neuroinflammatory processes.

Urolithin A Prevents Sleep-deprivation-induced Neuroinflammation and Mitochondrial Dysfunction in Young and Aged Mice

Sleep deprivation (SD) has reached epidemic proportions worldwide and negatively affects people of all ages. Cognitive impairment induced by SD involves neuroinflammation and mitochondrial dysfunction, but the underlying mechanisms are largely unknown. Urolithin A (UA) is a natural compound that can reduce neuroinflammation and improve mitochondrial health, but its therapeutic effects in a SD model have not yet been studied. Young (3-months old) and aged (12-months old) mice were sleep deprived for 24 h, and UA (2.5 mg/kg or 10 mg/kg) was injected intraperitoneally for 7 consecutive days before the SD period. Immunofluorescent staining, western blotting, and RT-PCR were employed to evaluate levels of proteins involved in neuroinflammation and mitochondrial function. Transmission electron microscope and Golgi-Cox staining were used to evaluate mitochondrial and neuronal morphology, respectively. Finally, contextual fear conditioning and the Morris water maze test were conducted to assess hippocampal learning and memory. In the hippocampus of young (3 months-old) and aged (12 months-old) mice subjected to 24 h SD, pretreatment with UA prevented the activation of microglia and astrocytes, NF-κB-NLRP3 signaling and IL-1β, IL6, TNF-α cytokine production, thus ameliorating neuroinflammation. Furthermore, UA also attenuated SD-induced mitochondrial dysfunction, normalized autophagy and mitophagy and protected hippocampal neuronal morphology. Finally, UA prevented SD-induced hippocampal memory impairment. Cumulatively, the results show that UA imparts cognitive protection by reducing neuroinflammation and enhancing mitochondrial function in SD mice. This suggests that UA shows promise as a therapeutic for the treatment of SD-induced neurological disorders.

Single-neuron neurodegeneration as a degenerative model for Parkinson's disease

The positive effect of levodopa in the treatment of Parkinson's disease, although it is limited in time and has severe side effects, has encouraged the scientific community to look for new drugs that can stop the neurodegenerative process or even regenerate the neuromelanin-containing dopaminergic nigrostriatal neurons. Successful preclinical studies with coenzyme Q10, mitoquinone, isradipine, nilotinib, TCH346, neurturin, zonisamide, deferiprone, prasinezumab, and cinpanemab prompted clinical trials. However, these failed and after more than 50 years levodopa continues to be the key drug in the treatment of the disease, despite its severe side effects after 4-6 years of chronic treatment. The lack of translated successful results obtained in preclinical investigations based on the use of neurotoxins that do not exist in the human body as new drugs for Parkinson's disease treatment is a big problem. In our opinion, the cause of these failures lies in the experimental animal models involving neurotoxins that do not exist in the human body, such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 6-hydroxydopamine, that induce a very fast, massive and expansive neurodegenerative process, which contrasts with the extremely slow one of neuromelanin-containing dopaminergic neurons. The exceedingly slow progress of the neurodegenerative process of the nigrostriatal neurons in idiopathic Parkinson's patients is due to (i) a degenerative model in which the neurotoxic effect of an endogenous neurotoxin affects a single neuron, (ii) a neurotoxic event that is not expansive and (iii) the fact that the neurotoxin that triggers the neurodegenerative process is produced inside the neuromelanin-containing dopaminergic neurons. The endogenous neurotoxin that fits this degenerative model involving one single neuron at a time is aminochrome, since it (i) is generated within neuromelanin-containing dopaminergic neurons, (ii) does not cause an expansive neurotoxic effect and (iii) triggers all the mechanisms involved in the neurodegenerative process of the nigrostriatal neurons in idiopathic Parkinson's disease. In conclusion, based on the hypothesis that the neurodegenerative process of idiopathic Parkinson's disease corresponds to a single-neuron neurodegeneration model, we must search for molecules that increase the expression of the neuroprotective enzymes DT-diaphorase and glutathione transferase M2-2. It has been observed that the activation of the Kelch-like ECH-associated protein 1/nuclear factor (erythroid-derived 2)-like 2 pathway is associated with the transcriptional activation of the DT-diaphorase and glutathione transferase genes.

Mechanism and role of mitophagy in the development of severe infection

Mitochondria produce adenosine triphosphate and potentially contribute to proinflammatory responses and cell death. Mitophagy, as a conservative phenomenon, scavenges waste mitochondria and their components in the cell. Recent studies suggest that severe infections develop alongside mitochondrial dysfunction and mitophagy abnormalities. Restoring mitophagy protects against excessive inflammation and multiple organ failure in sepsis. Here, we review the normal mitophagy process, its interaction with invading microorganisms and the immune system, and summarize the mechanism of mitophagy dysfunction during severe infection. We highlight critical role of normal mitophagy in preventing severe infection.

Minocycline alleviates LPS-induced cognitive dysfunction in mice by inhibiting the NLRP3/caspase-1 pathway

BACKGROUND

Growing experimental evidence indicates that cognitive impairment is linked to neuroinflammation. Minocycline (MINO), an antibiotic known for its anti-inflammatory, has shown promise in alleviating cognitive impairment. Nonetheless, the exact mechanism through which MINO improves cognitive impairment is not yet understood.

METHODS

A neuroinflammatory model was establish by utilizing lipopolysaccharide. The assessment of mice's cognitive and learning abilities was conducted through the MWM and Y-maze tests. The evaluation of hippocampal neuronal injury and microglial activation were achieved by performing HE staining and IHC, respectively. To evaluate BV2 cell viability and apoptosis, the CCK-8 and Hoechst 33342/PI staining assays were employed. In order to assess the protein and RNA expression levels of NLRP3, caspase-1, IL-1β, IL-18, Iba-1, and Bcl2/Bax, WB and RT-qPCR were utilized. Additionally, the inhibitory effect of MINO on apoptosis by targeting the NLRP3/caspase-1 pathway was investigated using Nigericin.

RESULTS

MINO was effective in reducing the time it took for mice to escape from the test, increasing the number of platforms they crossed, and mitigating damage to the hippocampus while also suppressing microglial activation and the expression of Iba-1 in a neuroinflammatory model caused by LPS. Furthermore, MINO improved the viability of BV2 cell and reduced apoptosis. It also had the effect of reducing the expression levels of NLRP3/Caspase-1, IL-1β, IL-18, and BAX, while upregulating the expression of Bcl2. Additionally, MINO was found to downregulate the NLRP3 expression, which is specifically activated by nigericin.

CONCLUSION

The protective effect of MINO relies on the crucial involvement of the NLRP3/caspase-1 pathway.

The cGAS-STING signaling pathway is modulated by urolithin A

During aging, general cellular processes, including autophagic clearance and immunological responses become compromised; therefore, identifying compounds that target these cellular processes is an important approach to improve our health span. The innate immune cGAS-STING pathway has emerged as an important signaling system in the organismal defense against viral and bacterial infections, inflammatory responses to cellular damage, regulation of autophagy, and tumor immunosurveillance. These key functions of the cGAS-STING pathway make it an attractive target for pharmacological intervention in disease treatments and in controlling inflammation and immunity. Here, we show that urolithin A (UA), an ellagic acid metabolite, exerts a profound effect on the expression of STING and enhances cGAS-STING activation and cytosolic DNA clearance in human cell lines. Animal laboratory models and limited human trials have reported no obvious adverse effects of UA administration. Thus, the use of UA alone or in combination with other pharmacological compounds may present a potential therapeutic approach in the treatment of human diseases that involves aberrant activation of the cGAS-STING pathway or accumulation of cytosolic DNA and this warrants further investigation in relevant transgenic animal models.

Anesthesia/surgery-induced learning and memory dysfunction by inhibiting mitophagy-mediated NLRP3 inflammasome inactivation in aged mice

Postoperative cognitive dysfunction (POCD) is a common postoperative complication, not only affects the quality of life of the elderly and increases the mortality rate, but also brings a greater burden to the family and society. Previous studies demonstrated that Nod-like receptor protein 3 (NLRP3) inflammasome participates in various inflammatory and neurodegenerative diseases. However, possible mitophagy mechanism in anesthesia/surgery-elicited NLRP3 inflammasome activation remains to be elucidated. Hence, this study clarified whether mitophagy dysfunction is related to anesthesia/surgery-elicited NLRP3 inflammasome activation. POCD model was established in aged C57BL/6 J mice by tibial fracture fixation under isoflurane anesthesia. Morris Water Maze (MWM) was used to evaluate learning and memory abilities. We found that in vitro experiments, lipopolysaccharide (LPS) significantly facilitated NLRP3 inflammasome activation and mitophagy inhibition in BV2 cells. Rapamycin restored mitophagy and improved mitochondrial function, and inhibited NLRP3 inflammasome activation induced by LPS. In vivo experiments, anesthesia and surgery caused upregulation of hippocampal NLRP3, caspase recruitment domain (ASC) and interleukin-1β (IL-1 β), and downregulation of microtubule-associated protein light chain 3II (LC3II) and Beclin1 in aged mice. Olaparib inhibited anesthesia/surgery-induced NLRP3, ASC, and IL-1β over-expression in the hippocampus, while upregulated the expression of LC3II and Beclin1. Furthermore, Olaparib improved cognitive impairment in older mice. These results revealed that mitophagy was involved in NLRP3 inflammasome-mediated anesthesia/surgery-induced cognitive deficits in aged mice. Overall, our results suggested that mitophagy was related in NLRP3 inflammasome-induced cognitive deficits after anesthesia and surgery in aged mice. Activating mitophagy may have clinical benefits in the prevention of cognitive impairment induced by anesthesia and surgery in elderly patients.