Mechanism of pyroptosis in neurodegenerative diseases and its therapeutic potential by traditional Chinese medicine

Berberine chloride loaded nano-PEGylated liposomes attenuates imidacloprid-induced neurotoxicity by inhibiting NLRP3/Caspase-1/GSDMD-mediated pyroptosis

Concerns have been expressed about imidacloprid (IMI), one of the most often used pesticides, and its potential neurotoxicity to non-target organisms. Chronic neuroinflammation is central to the pathology of several neurodegenerative disorders. Hence, exploring the molecular mechanism by which IMI would trigger neuroinflammation is particularly important. This study examined the neurotoxic effects of oral administration of IMI (45 mg/kg/day for 30 days) and the potential neuroprotective effect of berberine (Ber) chloride loaded nano-PEGylated liposomes (Ber-Lip) (10 mg/kg, intravenously every other day for 30 days) using laboratory rat. The histopathological changes, anti-oxidant and oxidative stress markers (GSH, SOD, and MDA), proinflammatory cytokines (IL1β and TNF-α), microglia phenotype markers (CD86 and iNOS for M1; CD163 for M2), the canonical pyroptotic pathway markers (NLRP3, caspase-1, GSDMD, and IL-18) and Alzheimer's disease markers (Neprilysin and beta amyloid [Aβ] deposits) were assessed. Oral administration of IMI resulted in apparent cerebellar histopathological alterations, oxidative stress, predominance of M1 microglia phenotype, significantly upregulated NLRP3, caspase-1, GSDMD, IL-18 and Aβ deposits and significantly decreased Neprilysin expression. Berberine reduced the IMI-induced aberrations in the measured parameters and improved the IMI-induced histopathological and ultrastructure alterations brought on by IMI. This study highlights the IMI neurotoxic effect and its potential contribution to the development of Alzheimer's disease and displayed the neuroprotective effect of Ber-Lip.

Salidroside ameliorates neuroinflammation in autistic rats by inhibiting NLRP3/Caspase-1/GSDMD signal pathway

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that place a huge economic and emotional burden on society. Salidroside (Sal) has been reported to have therapeutic effects in a variety of neurological disorders such as Alzheimer's disease （AD） and Parkinson's disease (PD), however no studies have been conducted to show whether salidroside is effective in ASD. Pyroptosis is involved in the pathology of a variety of neurological disorders, but has not been reported in ASD.

OBJECTIVES

The aim of this study was to investigate whether pyroptosis is involved in the pathological mechanisms of ASD, and whether salidroside has an impact on the pathological process of ASD by regulating pyroptosis.

METHODS

We obtained a rat model of offspring ASD by prenatal intraperitoneal administration of valproic acid (VPA, 500 mg/kg) to pregnant rats, and we treated seven-day-old offspring ASD with salidroside (Sal, 30 mg/kg once daily) by gavage for 28 days as the salidroside treatment group. We examined the hippocampal state of ASD rats and the effect of salidroside on the hippocampus of VPA-induced ASD rats. In addition, in BV2 cells treated with LPS/Nig, we explored the mechanisms by which salidroside regulates neuroinflammation and pyroptosis in vitro.

RESULTS

In vivo, we observed VPA-induced hippocampal neuronal damage and activation of the NLRP3/Caspase-1/GSDMD signalling pathway in ASD rats, while salidroside alleviated neuronal damage in ASD rats. In vitro, we found that salidroside inhibited LPS/Nig-induced neuroinflammation and activation of the NLRP3/Caspase-1/GSDMD signalling pathway. These results suggest that the therapeutic effect of salidroside on hippocampal damage in ASD rats may be related to NLRP3/Caspase-1/GSDMD-mediated pyroptosis.

CONCLUSIONS

Our work showed that salidroside ameliorates hippocampal neurological damage in ASD rats by targeting NLRP3/Caspase-1/GSDMD-mediated pyroptosis, providing a potential therapy drug for ASD.

The Interplay of Carveol and All-Trans Retinoic Acid (ATRA) in Experimental Parkinson's Disease: Role of Inflammasome-Mediated Pyroptosis and Nrf2

Parkinson's disease (PD) is a debilitating and the second most common neurodegenerative disorder with a high prevalence. PD has a multifaceted etiology characterized by an altered redox state and an excessive inflammatory response. Extensive research has consistently demonstrated the role of the nuclear factor E2-related factor (Nrf2) and inflammasomes, notably NLRP3 in neurodegenerative diseases. In this study, our focus was on exploring the potential neuroprotective properties of carveol in Parkinson's disease. Our findings suggest that carveol may exhibit these effects through Nrf2 and by suppressing pyroptosis. Male albino mice were treated with carveol, and the animal PD model was induced through a single intranigral dose of 2 µg/2µl lipopolysaccharide (LPS). To further demonstrate the essential role of the Nrf2 pathway, we utilized all-trans retinoic acid (ATRA) to inhibit the Nrf2. Our finding showed the induction of pyroptosis as evidenced by increased levels of NLRP3 and other inflammatory mediators, including IL-1β, iNOS, p-NFKB, and apoptotic cell death indicated by positive fluoro Jade B (FJB) staining. Moreover, increased levels of lipid peroxides and reactive oxygen species indicated a significant rise in oxidative stress due to LPS. The administration of carveol mitigates oxidative stress and suppresses inflammatory pathways through the augmentation of intrinsic antioxidant defenses, primarily via the activation of the Nrf2. Conversely, ATRA reversed carveol protective effects by increasing FJB-positive cells, inflammatory and oxidative biomarkers. Taken together, our findings suggest that carveol mitigated LPS-induced Parkinson-like symptoms, partially through the activation of the Nrf2 and downregulation of pyroptosis notably NLRP3.

B355252 Suppresses LPS-Induced Neuroinflammation in the Mouse Brain

B355252 is a small molecular compound known for potentiating neural growth factor and protecting against neuronal cell death induced by glutamate in vitro and cerebral ischemia in vivo. However, its other biological functions remain unclear. This study aims to investigate whether B355252 suppresses neuroinflammatory responses and cell death in the brain. C57BL/6j mice were intraperitoneally injected with a single dosage of lipopolysaccharide (LPS, 1 mg/kg) to induce inflammation. B355252 (1 mg/kg) intervention was started two days prior to the LPS injection. The animal behavioral changes were assessed pre- and post-LPS injections. The animal brains were harvested at 4 and 24 h post-LPS injection, and histological, biochemical, and cytokine array outcomes were examined. Results showed that B355252 improved LPS-induced behavioral deterioration, mitigated brain tissue damage, and suppressed the activation of microglial and astrocytes. Furthermore, B355252 reduced the protein levels of key pyroptotic markers TLR4, NLRP3, and caspase-1 and inhibited the LPS-induced increases in IL-1β, IL-18, and cytokines. In conclusion, B355252 demonstrates a potent anti-neuroinflammatory effect in vivo, suggesting that its potential therapeutic value warrants further investigation.

Another Use for a Proven Drug: Experimental Evidence for the Potential of Artemisinin and Its Derivatives to Treat Alzheimer's Disease

Plant-derived multitarget compounds may represent a promising therapeutic strategy for multifactorial diseases, such as Alzheimer's disease (AD). Artemisinin and its derivatives were indicated to beneficially modulate various aspects of AD pathology in different AD animal models through the regulation of a wide range of different cellular processes, such as energy homeostasis, apoptosis, proliferation and inflammatory pathways. In this review, we aimed to provide an up-to-date overview of the experimental evidence documenting the neuroprotective activities of artemi-sinins to underscore the potential of these already-approved drugs for treating AD also in humans and propose their consideration for carefully designed clinical trials. In particular, the benefits to the main pathological hallmarks and events in the pathological cascade throughout AD development in different animal models of AD are summarized. Moreover, dose- and context-dependent effects of artemisinins are noted.

Necrosis Links Neurodegeneration and Neuroinflammation in Neurodegenerative Disease

The mechanisms of neuronal cell death in neurodegenerative disease remain incompletely understood, although recent studies have made significant advances. Apoptosis was previously considered to be the only mechanism of neuronal cell death in neurodegenerative diseases. However, recent findings have challenged this dogma, identifying new subtypes of necrotic neuronal cell death. The present review provides an updated summary of necrosis subtypes and discusses their potential roles in neurodegenerative cell death. Among numerous necrosis subtypes, including necroptosis, paraptosis, ferroptosis, and pyroptosis, transcriptional repression-induced atypical cell death (TRIAD) has been identified as a potential mechanism of neuronal cell death. TRIAD is induced by functional deficiency of TEAD-YAP and self-amplifies via the release of HMGB1. TRIAD is a feasible potential mechanism of neuronal cell death in Alzheimer's disease and other neurodegenerative diseases. In addition to induction of cell death, HMGB1 released during TRIAD activates brain inflammatory responses, which is a potential link between neurodegeneration and neuroinflammation.

Herbal medicine and gut microbiota: exploring untapped therapeutic potential in neurodegenerative disease management

The gut microbiota that exists in the human gastrointestinal tract is incredibly important for the maintenance of general health as it contributes to multiple aspects of host physiology. Recent research has revealed a dynamic connection between the gut microbiota and the central nervous system, that can influence neurodegenerative diseases (NDs). Indeed, imbalances in the gut microbiota, or dysbiosis, play a vital role in the pathogenesis and progression of human diseases, particularly NDs. Herbal medicine has been used for centuries to treat human diseases, including NDs. These compounds help to relieve symptoms and delay the progression of NDs by improving intestinal barrier function, reducing neuroinflammation, and modulating neurotransmitter production. Notably, herbal medicine can mitigate the progression of NDs by regulating the gut microbiota. Therefore, an in-depth understanding of the potential mechanisms by which herbal medicine regulates the gut microbiota in the treatment of NDs can help explain the pathogenesis of NDs from a novel perspective and propose novel therapeutic strategies for NDs. In this review, we investigate the potential neuroprotective effects of herbal medicine, focusing on its ability to regulate the gut microbiota and restore homeostasis. We also highlight the challenges and future research priorities of the integration of herbal medicine and modern medicine. As the global population ages, access to this information is becoming increasingly important for developing effective treatments for these diseases.

The pyroptosis mediated biomarker pattern: an emerging diagnostic approach for Parkinson's disease

BACKGROUND

Parkinson's disease (PD) affects 1% of people over 60, and long-term levodopa treatment can cause side effects. Early diagnosis is of great significance in slowing down the pathological process of PD. Multiple pieces of evidence showed that non-coding RNAs (ncRNAs) could participate in the progression of PD pathology. Pyroptosis is known to be regulated by ncRNAs as a key pathological feature of PD. Therefore, evaluating ncRNAs and pyroptosis-related proteins in serum could be worthy biomarkers for early diagnosis of PD.

METHODS

NcRNAs and pyroptosis/inflammation mRNA levels were measured with reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). Luciferase assays were performed to confirm GSDME as a target of miR-675-5p and HMGB1 as a target of miR-1247-5p. In the serum of healthy controls (n = 106) and PD patients (n = 104), RT-qPCR was utilized to assess miR-675-5p, miR-1247-5p, and two related ncRNAs (circSLC8A1and lncH19) levels. The enzyme-linked immunosorbent assay measured serum levels of pyroptosis-related proteins in controls (n = 54) and PD patients (n = 70).

RESULTS

Our data demonstrated that miR-675-5p and miR-1247-5p significantly changed in PD neuron and animal models. Overexpressed miR-675-5p or downregulated miR-1247-5p could regulate pyroptosis and inflammation in PD neuron models. Using the random forest algorithm, we constructed a classifier based on PD neuron-pyroptosis pathology (four ncRNAs and six proteins) having better predictive power than single biomarkers (AUC = 92%). Additionally, we verified the performance of the classifier in early-stage PD patients (AUC ≥ 88%).

CONCLUSION

Serum pyroptosis-related ncRNAs and proteins could serve as reliable, inexpensive, and non-invasive diagnostic biomarkers for PD.

LIMITATIONS

All participants were from the same region. Additionally, longitudinal studies in the aged population are required to explore the practical application value of the classifier.

Total flavonoids of Cynomorium songaricum attenuates cognitive defects in an Aβ 1-42 -induced Alzheimer's disease rat model by activating BDNF/TrkB signaling transduction

Alzheimer's disease (AD) is a degenerative disorder characterized by cognitive dysfunction and BDNF/TrkB is a well-conceived anti-AD signaling. Cynomorium songaricum Rupr. ( C. songaricum ) is a herb with promising neuroprotective effects and the function is majorly attributed to flavonoids. The current study attempted to explore the effects of total flavonoids of C. songaricum (CS) on AD model by focusing on changes in BDNF/TrkB axis. AD model was induced in rats via transcranial injection of Aβ 1-42 and AD symptoms treated with CS of three doses. Donepezil was used as the positive control. Changes in rat memory and learning abilities, brain histological, apoptosis, production of neurotransmitters, BDNF/TrkB axis, and apoptosis-related markers were measured. The injection of Aβ 1-42 induced cognitive dysfunction in AD rats. The integrity of brain tissue structure was destructed and apoptosis was induced in AD rats, in which was found the increased production of AChE and Aβ 1-42 , and decreased production of ChAT, ACH. At the molecular level, the expression of BDNF, TrkB, and Bcl-2 was suppressed, while the expression of Bax, caspase-3, and caspase-9 was induced. After the administration of CS, the memory and learning abilities of rats were improved, the production of neurotransmitter was restored, ordered arrangement of pyramidal cells was retained, and neuron apoptosis was inhibited. The attenuation of Aβ 1-42 -indcued impairments was associated with the activation of BDNF/TrkB axis and blockade of apoptosis-related pathways. Collectively, CS can improve learning and memory abilities in Aβ 1-42 -induced AD model rats. which may depend on the activation of the hippocampal BDNF/TrkB signaling pathway.

Quercetin Alleviated Inflammasome-Mediated Pyroptosis and Modulated the mTOR/P70S6/P6/eIF4E/4EBP1 Pathway in Ischemic Stroke

Stroke ranks as the world's second most prevalent cause of mortality, and it represents a major public health concern with profound economic and social implications. In the present study, we elucidated the neuroprotective role of quercetin on NLRP3-associated pyroptosis, Nrf2-coupled anti-inflammatory, and mTOR-dependent downstream pathways. Male Sprague Dawley rats were subjected to 72 h of transient middle cerebral artery ischemia, followed by the administration of 10 mg/kg of quercetin. Our findings demonstrated that MCAO induced elevated ROS which were coupled to inflammasome-mediated pyroptosis and altered mTOR-related signaling proteins. We performed ELISA, immunohistochemistry, and Western blotting to unveil the underlying role of the Nrf2/HO-1 and PDK/AKT/mTOR pathways in the ischemic cortex and striatum. Our results showed that quercetin post-treatment activated the Nrf2/HO-1 cascade, reversed pyroptosis, and modulated the autophagy-related pathway PDK/AKT/mTOR/P70S6/P6/eIF4E/4EBP1. Further, quercetin enhances the sequestering effect of 14-3-3 and reversed the decrease in interaction between p-Bad and 14-3-3 and p-FKHR and 14-3-3. Our findings showed that quercetin exerts its protective benefits and rescues neuronal damage by several mechanisms, and it might be a viable neuroprotective drug for ischemic stroke therapy.