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Introduction Recent advances have highlighted the relationships between gut dysbiosis and Parkinson's disease (PD). Microbiota transplantation from PD patients to mice can induce increased alpha‐synuclein‐mediated motor deficits. Human studies have identified differences in the gut microbiota of PD patients compared to healthy controls. We undertook a systematic review to evaluate the available evidence for the involvement of gut bacteria in the etiology of PD. Methods The PubMed databank, the China National Knowledge Infrastructure databank, and Wanfang Data were searched from inception until June 2021 to identify human case–control studies that investigated relationships between PD and microbiota quantified from feces. We evaluated the resulting studies focusing on bacterial taxa that were different between PD patients and healthy controls. Results Twenty‐six studies were found in which 53 microbial families and 98 genera exhibited differences between patients with PD and healthy controls. The genera identified by more than two studies as increased in PD were Bifidobacterium, Alistipes, Christensenella, Enterococcus, Oscillospira, Bilophila, Desulfovibrio, Escherichia/Shigella, and Akkermansia, while Prevotella, Blautia, Faecalibacterium, Fusicatenibacter, and Haemophilus had three or more reports of being lower in PD patients. More than one report demonstrated that Bacteroides, Odoribacter, Parabacteroides, Butyricicoccus, Butyrivibrio, Clostridium, Coprococcus, Lachnospira, Lactobacillus, Megasphaera, Phascolarctobacterium, Roseburia, Ruminococcus, Streptococcus, and Klebsiella were altered in both directions. Conclusion Our review shows that the involvement of the gut microbiome in the etiology of PD may involve alterations of short‐chain fatty acids (SCFAs)‐producing bacteria and an increase in putative gut pathobionts. SCFAs‐producing bacteria may vary above or below an “optimal range,” causing imbalances. Considering that Bifidobacterium, Lactobacillus, and Akkermansia are beneficial for human health, increased Bifidobacterium and Lactobacillus in the PD gut microbiome may be associated with PD medications, especially COMT inhibitors, while a high level of Akkermansia may be associated with aging. The role of gut bacteria in association with Parkinson's disease (PD) may involve the alterations of bacteria with the capacity to produce short‐chain fatty acids (SCFAs) and an increase in putative pathobionts, which may work together to potentially impair the intestinal barrier and/or blood–brain barrier integrity, stimulating systemic and neural inflammation. SCFAs‐producing bacteria may reduce or increase outside of an “optimal range”. Considering that Bifidobacterium, Lactobacillus, and Akkermansia are beneficial for human health, the increased Bifidobacterium and Lactobacillus may be associated with PD medications, especially COMT inhibitors, while a high level of Akkermansia may be associated with aging.

In the early stage of intracerebral hemorrhage (ICH), rebleeding occurs when blood from the initial hematoma permeates the surrounding brain parenchyma through the disrupted blood–brain barrier (BBB), exacerbating brain injury. Neuroinflammation is a critical driver of the pathological processes underlying this phenomenon. Research on microglia near early hematomas revealed that promoting the transition of microglia to the M2 phenotype could mitigate perihematomal inflammatory damage. Recent studies have shown that the nuclear receptor-related 1 protein (NR4A2) can regulate microglial function and inhibit inflammation. However, the functions of NR4A2 in the development of ICH are still unclear. In this study, we explored the potential protective effect and mechanism of NR4A2 in ICH models. Our results demonstrated that the expression of NR4A2 was significantly decreased in both ICH rats and cell models. Increasing NR4A2 activity could effectively decrease the hematoma volume, improve the neurological prognosis and alleviate perihematomal BBB damage. In vivo and in vitro experiments revealed that NR4A2 inhibited perihematomal inflammatory damage by driving microglial polarization toward the anti-inflammatory M2 phenotype. Mechanistically, NR4A2 targeted TLR4 and inhibited the TRAF6/NF-κB pathway, thereby promoting M2 microglial polarization, reducing inflammatory cell extravasation and maintaining the integrity of the BBB. Conversely, the protective effects of NR4A2 were negated when CRX-527 (a TLR4 agonist) was introduced. These findings suggest that NR4A2 represents a promising therapeutic target for ICH. Graphical abstract

Microglial activation-induced neuroinflammation and impaired neuronal mitophagy are recognized as pivotal pathogeneses in Parkinson’s disease (PD). However, the role of microglial mitophagy in microglial activation during PD development remains unclear, and therapeutic interventions targeting this interaction are lacking. Rhapontigenin (Rhap), a stilbenoid enriched in Vitis vinifera , exhibits dual anti-neuroinflammatory and mitophagy-enhancing properties, but its therapeutic potential and mechanisms in PD are unexplored. This study aimed to investigate the therapeutic efficacy of Rhap on neurodegeneration in a PD model and explore its underlying mechanism. Here, we showed that Rhap administration significantly ameliorated motor deficits, dopaminergic neuron loss, and neuroinflammation in MPTP-induced PD mice. Mechanistically, Rhap suppressed neuroinflammation by inhibiting the cGAS-STING-NF-κB signaling axis in both PD model mice and MPP⁺-induced BV2 microglia. Crucially, its anti-inflammatory effects depend on the PINK1-mediated enhancement of microglial mitophagy to control cytosolic mtDNA leakage. Specifically, Rhap bound to PINK1 strengthened the PINK1-DRP1 interaction, promoted mitochondrial fission in damaged organelles, and enhanced mitophagy clearance. This mitophagy activation prevents cytosolic leakage of mitochondrial DNA (mtDNA), thereby attenuating mtDNA-cGAS-STING-NF-κB-derived neuroinflammation and subsequent neurodegeneration in PD. PINK1 deficiency in BV2 microglia abolished Rhap’s ability to suppress mtDNA-cGAS-STING-NF-κB activation and enhance mitophagy. Overall, our study reveals a previously unrecognized mechanism by which Rhap ameliorates PD-associated neurodegeneration through dual modulation of PINK1/DRP1-dependent microglial mitophagy and the mtDNA-cGAS-STING-NF-κB neuroinflammatory axis, suggesting a potential therapeutic strategy for PD and related neurodegenerative disorders.

The leucine-rich repeat kinase 2 (LRRK2) phosphorylates a subset of RAB GTPases, and their phosphorylation levels are elevated by Parkinson’s disease (PD)-linked mutations of LRRK2. However, the precise function of the LRRK2-regulated RAB GTPase in the brain remains to be elucidated. Here, we identify RAB12 as a robust LRRK2 substrate in the mouse brain through phosphoproteomics profiling and solve the structure of RAB12-LRRK2 protein complex through Cryo-EM analysis. Mechanistically, RAB12 cooperates with LRRK2 to inhibit primary ciliogenesis and regulate centrosome homeostasis in astrocytes through enhancing the phosphorylation of RAB10 and recruiting RILPL1, while the functions of RAB12 require a direct interaction with LRRK2 and LRRK2 activity. Furthermore, the ciliary and centrosome defects caused by the PD-linked LRRK2-G2019S mutation are prevented by Rab12 deletion in astrocytes. Thus, our study reveals a physiological function of the RAB12-LRRK2 complex in regulating ciliogenesis and centrosome homeostasis. The RAB12-LRRK2 structure offers a guidance in the therapeutic development of PD by targeting the RAB12-LRRK2 interaction. LRRK2 variants are linked to Parkinson’s disease. Here, the authors solve the Cryo-EM structure of LRRK2 complexed to RAB12 and demonstrate that their interaction regulates cilia formation in astrocytes.

Parkinson’s disease (PD) is the most common progressive neurodegenerative movement disorder, which is characterized by dopaminergic (DA) neuron death and the aggregation of neurotoxic α-synuclein. Cntnap4 , a risk gene of autism, has been implicated to participate in PD pathogenesis. Here we showed Cntnap4 lacking exacerbates α-synuclein pathology, nigrostriatal DA neuron degeneration and motor impairment, induced by injection of adeno-associated viral vector (AAV)-mediated human α-synuclein overexpression (AAV- h α-Syn). This scenario was further validated in A53T α-synuclein transgenic mice injected with AAV-Cntnap4 shRNA. Mechanistically, α-synuclein derived from damaged DA neuron stimulates astrocytes to release complement C3, activating microglial C3a receptor (C3aR), which in turn triggers microglia to secrete complement C1q and pro-inflammatory cytokines. Thus, the astrocyte–microglia crosstalk further drives DA neuron death and motor dysfunction in PD. Furthermore, we showed that in vivo depletion of microglia and microglial targeted delivery of a novel C3aR antagonist (SB290157) rescue the aggravated α-synuclein pathology resulting from Cntnap4 lacking. Together, our results indicate that Cntnap4 plays a key role in α-synuclein pathogenesis by regulating glial crosstalk and may be a potential target for PD treatment.

Obesity, a global health challenge, is a major risk factor for multiple life-threatening diseases, including diabetes, fatty liver, and cancer. There is an ongoing need to identify safe and tolerable therapeutics for obesity management. Herein, we show that treatment with artesunate, an artemisinin derivative approved by the FDA for the treatment of severe malaria, effectively reduces body weight and improves metabolic profiles in preclinical models of obesity, including male mice with overnutrition-induced obesity and male cynomolgus macaques with spontaneous obesity, without inducing nausea and malaise. Artesunate promotes weight loss and reduces food intake in obese mice and cynomolgus macaques by increasing circulating levels of Growth Differentiation Factor 15 (GDF15), an appetite-regulating hormone with a brainstem-restricted receptor, the GDNF family receptor α-like (GFRAL). Mechanistically, artesunate induces the expression of GDF15 in multiple organs, especially the liver, in mice through a C/EBP homologous protein (CHOP)-directed integrated stress response. Inhibition of GDF15/GFRAL signalling by genetic ablation of GFRAL or tissue-specific knockdown of GDF15 abrogates the anti-obesity effect of artesunate in mice with diet-induced obesity, suggesting that artesunate controls bodyweight and appetite in a GDF15/GFRAL signalling-dependent manner. These data highlight the therapeutic benefits of artesunate in the treatment of obesity and related comorbidities. Obesity is a global health challenge with an ongoing need for new medical treatments. Here, the authors show that artesunate, an FDA-approved treatment for severe malaria, can be repurposed for the treatment of obesity via GDF15/GFRAL signaling axis without overt side effects in mice and non-human primates.

Parkinson’s disease (PD) is characterized by progressive neurodegeneration closely linked to neuroinflammation and oxidative stress-induced damage and is characterized by the loss of dopaminergic (DAergic) neurons and the inflammatory response associated with glial cells. RRx-001 (RRx, 2-bromo-1-(3,3-dinitroazetidin-1-yl)ethanone) is a small-molecule immunoregulator. Recent studies have shown that it strongly inhibits NLRP3 (NOD-like receptor family pyrin domain containing 3) inflammasome activation, which is crucial for influencing neuroinflammation. However, the mechanism underlying the effect of RRx on PD remains unclear. In this study, we explored the potential effects of RRX on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice, detected the transcriptome and metabolome of the substantia nigra, and performed 16 S microbial diversity sequencing and metabolomics of the intestinal tract. Our study revealed that RRx obviously relieves MPTP-induced DAergic neuronal loss and motor disorders. Mechanistically, RRx reversed the upregulated expression of lipocalin-2 (LCN2) and NLRP3 inflammasome activation in a PD model. Crucially, its protective effects on DAergic neurons involved improving LCN2-NLRP3 inflammasome activation-mediated astrocyte pyroptosis. RRx also reduced the levels of metabolites and signalling pathways associated with oxidative stress and PD in the substantia nigra. Furthermore, the 16 S rDNA analysis and metabolomic analysis of faecal pellets revealed that the intestinal tract of the RRx-treated PD mice presented a greater abundance of Deferribacterota at the phylum level than that of the PD model mice, and the gut microbiota metabolites and pathways were altered. Overall, the results of this study indicate that RRx has multiple effects on PD.

Background The glucocerebrosidase ( GBA ) and leucine-rich repeat kinase 2 ( LRRK2 ) genes are associated with the risk of sporadic Parkinson’s disease (PD). As an environmental factor, hypoxic insults may impair dopamine neurons in the substantia nigra and exacerbate PD symptoms. However, covariants of GBA and LRRK2 combined with hypoxic insults in clinical cases of Parkinsonism have not yet been reported. Case presentation A 69-year-old male patient with PD and his relatives were clinically characterized and sequenced using the whole-exome technique. A novel covariant, c.1448 T  >  C ( p. L483P , rs421016 ) on GBA and c.691 T  >  C ( p. S231P , rs201332859 ) on LRRK2 were identified in this patient who first developed bradykinesia and rigidity in the neck at one month after an acute hypoxic insult during mountaineering. The patient presented with a mask-like face, festinating gait, asymmetric bradykinesia, and moderate rigidity. These symptoms were treated with levodopa and pramipexole, resulting in a 65% improvement in the Unified Parkinson’s Disease Rating Scale (UPDRS) motor score. These parkinsonian symptoms persisted and developed with hallucinations, constipation, and rapid eye movement sleep behavior disorder. After 4 years, the patient exhibited a wearing-off phenomenon and died from pulmonary infection 8 years after disease onset. His parents, wife, and siblings were not diagnosed with PD, and his son carried p. L483P without Parkinsonism-like symptoms. Conclusions This is a case report of PD after hypoxic insult in a patient carrying a covariant of GBA and LRRK2 . This study may help us understand the interaction between genetic and environmental factors in clinical PD.

Parkinson's disease (PD) is characterized by the progressive deterioration of dopamine (DA) neurons, and therapeutic endeavors are aimed at preventing DA loss. However, lack of effective brain delivery approaches limits this strategy. In this study, a “Trojan horse” system is used for substantia nigra‐targeted delivery of a blood brain barrier‐penetrating peptide (RVG29) conjugated to the surface of nanoparticles loaded with the natural autophagy inducer 4,4′‐dimethoxychalcone (DMC) (designated as RVG‐nDMC). Here, the neuroprotective effects of DMC are demonstrated in PD. Specifically, RVG‐nDMC penetrates the blood brain barrier with enhanced brain‐targeted delivery efficiency and is internalized by DA neurons and microglia. In vivo studies demonstrate that RVG‐nDMC ameliorates motor deficits and nigral DA neuron death in PD mice without causing overt adverse effects in the brain or other major organs. Moreover, RVG‐nDMC reverses tyrosine hydroxylase ubiquitination and degradation, alleviates oxidative stress in DA neurons, and exerts antiinflammatory effects in microglia. The “Trojan horse” strategy for targeted delivery of DMC thus provides a potentially powerful and clinically feasible approach for PD intervention. A Trojan horse system (RVG‐nDMC) is constructed for blood brain barrier‐penetrated delivery of 4,4′‐dimethoxychalcone (DMC) to ameliorate motor deficits and nigral dopamine (DA) neuronal death in Parkinson's disease. Mechanistically, RVG‐nDMC reduces tyrosine hydroxylase ubiquitination and degradation, alleviates the oxidative stress in DA neurons, and exerts antiinflammation effects in microglia for synergistic Parkinsonian intervention.