The present study was designed to investigate the role of β‐amyloid (Aβ 1‐42 ) in inducing neuronal pyroptosis and its mechanism. Mice cortical neurons (MCNs) were used in this study, LPS + Nigericin was used to induce pyroptosis in MCNs (positive control group), and Aβ 1‐42 was used to interfere with MCNs. In addition, propidium iodide (PI) staining was used to examine cell permeability, lactate dehydrogenase (LDH) release assay was employed to detect cytotoxicity, immunofluorescence (IF) staining was used to investigate the expression level of the key protein GSDMD, Western blot was performed to detect the expression levels of key proteins, and enzyme‐linked immunosorbent assay (ELISA) was utilized to determine the expression levels of inflammatory factors in culture medium, including IL‐1β, IL‐18 and TNF‐α. Small interfering RNA (siRNA) was used to silence the mRNA expression of caspase‐1 and GSDMD, and Aβ 1‐42 was used to induce pyroptosis, followed by investigation of the role of caspase‐1‐mediated GSDMD cleavage in pyroptosis. In addition, necrosulfonamide (NSA), an inhibitor of GSDMD oligomerization, was used for pre‐treatment, and Aβ 1‐42 was subsequently used to observe the pyroptosis in MCNs. Finally, AAV9‐siRNA‐caspase‐1 was injected into the tail vein of APP/PS1 double transgenic mice (Alzheimer's disease mice) for caspase‐1 mRNA inhibition, followed by observation of behavioural changes in mice and measurement of the expression of inflammatory factors and pyroptosis‐related protein. As results, Aβ 1‐42 could induce pyroptosis in MCNs, increase cell permeability and enhance LDH release, which were similar to the LPS + Nigericin‐induced pyroptosis. Meanwhile, the expression levels of cellular GSDMD and p30‐GSDMD were up‐regulated, the levels of NLRP3 inflammasome and GSDMD‐cleaved protein caspase‐1 were up‐regulated, and the levels of inflammatory factors in the medium were also up‐regulated. siRNA intervention in caspase‐1 or GSDMD inhibited Aβ 1‐42 ‐induced pyroptosis, and NSA pre‐treatment also caused the similar inhibitory effects. The behavioural ability of Alzheimer's disease (AD) mice was relieved after the injection of AAV9‐siRNA‐caspase‐1, and the expression of pyroptosis‐related protein in the cortex and hippocampus was down‐regulated. In conclusion, Aβ 1‐42 could induce pyroptosis by GSDMD protein, and NLRP3‐caspase‐1 signalling was an important signal to mediate GSDMD cleavage, which plays an important role in Aβ 1‐42 ‐induced pyroptosis in neurons. Therefore, GSDMD is expected to be a novel therapeutic target for AD.

The previous study by our group has found that miRNA‐22 can inhibit pyroptosis by targeting GSDMD and improve the memory and motor ability of mice with Alzheimer's disease (AD) mice by inhibiting inflammatory response. In recent years, stem cells and their exosomes have been reported to have good therapeutic effects on AD; therefore, we hypothesize that miRNA‐22 is likely to play a synergistic therapeutic effect. In this study, adipose‐derived mesenchymal stem cells (ADMSCs) were transfected into miRNA‐22 mimic to obtain miRNA‐22 loaded exosomes (Exo‐miRNA‐22), which was further used for the treatment and nerve repair of AD. In brief, 4‐month‐old APP/PS1 mice were assigned into the control group, Exo and Exo‐miRNA‐22 groups. After exosome transplantation, we observed changes in the motor and memory ability of mice. In addition, ELISA was used to detect the expression of inflammatory factors in cerebrospinal fluid and peripheral blood, Nissl staining was used to assess the survival of mouse nerve cells, immunofluorescence staining was used to determine the activation of microglia, and Western blot was utilized to detect the expression of pyroptosis‐related proteins. As a result, the nerve function and motor ability were significantly higher in mice in the Exo‐miRNA‐22 group than those in the control group and Exo group. Meanwhile, the survival level of nerve cells in mice was higher in the Exo‐miRNA‐22 group, and the expression of inflammatory factors was lower than that of the Exo group, indicating Exo‐miRNA‐22 could significantly suppress neuroinflammation. In vitro culture of PC12 cells, Aβ25‐35‐induced cell damage, detection of PC12 apoptotic level, the release of inflammatory factors and the expression of pyroptosis‐related proteins showed that Exo‐miRNA‐22 could inhibit PC12 apoptosis and significantly decrease the release of inflammatory factors. In this study, we found that miRNA‐22‐loaded ADMSC‐derived exosomes could decrease the release of inflammatory factors by inhibiting pyroptosis, thereby playing a synergetic therapeutic role with exosomes on AD, which is of great significance in AD research.

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Objective This study was mainly conducted to explore the expression changes of GSDMD and conventional markers (including T‐Tau, Tau181p, and Aβ1–42) in the cerebrospinal fluid among patients with Alzheimer's disease (AD) and vascular dementia (VD), followed by determination of role of GSDMD in diagnosing and identifying AD and VD. Methods In this study, 60 patients with VD, 60 patients with AD, and 50 healthy controls were enrolled. Lumbar puncture was performed to collect cerebrospinal fluid samples. Patients with VD and patients with AD were evaluated using the Mini‐Mental State Examination (MMSE) scale, Montreal Cognitive Assessment (MoCA) scale, Clinical Dementia Rating (CDR) scale, Activity of Daily Living (ADL) scale, and Neuropsychiatric Inventory (NPI) questionnaire, aiming to determine the behavioral ability of patients. ELISA kit was purchased to determine the levels of GSDMD, T‐Tau, Tau181p, and Aβ1–42 in cerebrospinal fluid, and the expression of inflammatory factors, IL‐1β and IL‐6, was also detected. Results (1) The levels of GSDMD, T‐Tau, and Tau181p in the cerebrospinal fluid were higher in patients with AD than those of patients with VD and healthy controls, while the levels of Aβ1‐42 in the cerebrospinal fluid were lower in patients with AD than that in healthy controls and patients with VD. (2) GSDMD had good diagnostic accuracy in AD. Additionally, GSDMD, T‐Tau, Tau181p, and Aβ1‐42 had good discrimination accuracy in distinguishing AD and VD. (3) The expression levels of inflammatory factors (IL‐1β and IL‐6) in cerebrospinal fluid were higher in patients with AD than those of healthy controls and patients with VD, which were positively correlated with GSDMD expression. Conclusion The expression of GSDMD was increased in patients with AD, which could be used as a biomarker for AD diagnosis and identification from VD.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.