Study on the Role and Mechanism of Exosomes Derived from Dental Pulp Stem Cells in Promoting Regeneration of Myelin Sheath in Rats with Sciatic Nerve Injury

The prognosis of peripheral nerve injury (PNI) is usually poor, and currently, there is no effective treatment for PNI. Studies have shown that exosomes derived from mesenchymal stem cells could promote nerve regeneration by optimizing the function of endogenous Schwann cells (SCs), while the mechanism is unclear. Autophagy, a highly conserved intracellular catabolic process responsible for maintaining cellular homeostasis, has been proved to be involved in the regulation of nerve repair after injury. We explored the effect of exosomes derived from dental pulp stem cells (DPSC-Exos) on the regeneration of myelin sheath in rats with sciatic nerve injury (SNI). In vitro and in vivo experiments were performed to clarify whether the effect of DPSC-Exos is associated with autophagy of SCs and to reveal the mechanism at the molecular level. Our results showed that the SCs of SNI rats exhibited the obvious autophagic characteristics, and the increase of P53 expression was an internal factor of autophagy. Our mechanism research indicated that DPSC-Exos could deliver miR-122-5p from DPSCs into SCs and suppressed the rapamycin (RAPA)-induced autophagy in SCs by inhibiting P53 expression. Rescue experiments showed that both the use of GW4869 and overexpression of exogenous P53 in SCs could reverse the inhibitory effect of DPSCs on the autophagy in SCs from co-culture system. In short, our study indicated that DPSC-Exos could promote the regeneration of the myelin sheath through suppressing the autophagy in SCs caused by PNI via miR-122-5p/P53 pathway; this provides researchers with another option for precise repair of PNI.

Dopaminergic damage pattern predicts phenoconversion time in isolated rapid eye movement sleep behavior disorder

PURPOSE

The exact phenoconversion time from isolated rapid eye movement (REM) sleep behavior disorder (iRBD) to synucleinopathies remains unpredictable. This study investigated whole-brain dopaminergic damage pattern (DDP) with disease progression and predicted phenoconversion time in individual patients.

METHODS

Age-matched 33 iRBD patients and 20 healthy controls with 11C-CFT-PET scans were enrolled. The patients were followed up 2-10 (6.7 ± 2.0) years. The phenoconversion year was defined as the base year, and every 2 years before conversion was defined as a stage. Support vector machine with leave-one-out cross-validation strategy was used to perform prediction.

RESULTS

Dopaminergic degeneration of iRBD was found to occur about 6 years before conversion and then abnormal brain regions gradually expanded. Using DDP, area under curve (AUC) was 0.879 (90% sensitivity and 88.3% specificity) for predicting conversion in 0-2 years, 0.807 (72.7% sensitivity and 83.3% specificity) in 2-4 years, 0.940 (100% sensitivity and 84.6% specificity) in 4-6 years, and 0.879 (100% sensitivity and 80.7% specificity) over 6 years. In individual patients, predicted stages correlated with whole-brain dopaminergic levels (r =  - 0.740, p < 0.001).

CONCLUSION

Our findings suggest that DDP could accurately predict phenoconversion time of individual iRBD patients, which may help to screen patients for early intervention.

[The clinical application value of brain 18F-FDG PET/CT in the diagnostics of Parkinsonian syndromes]

Objective: To analyze the PET/CT imaging features of fluoride 18F-fluorodeoxyglucose (18F-FDG) in patients with various types of Parkinson's syndrome (PS), and to establish a "diagnostic tree" model of 18F-FDG PET/CT for PS. Methods: Data of patients with Parkinson's disease (PD), patients with multiple system atrophy cerebellar type (MSA-C), and patients with multiple system atrophy Parkinson's type (MSA-P)admitted to the Neurology Department of Huashan Hospital affiliated to Fudan University from January 2019 to December 2021. 18F-FDG PET/CT examination was conducted in all patients. Clinical and follow-up data was collected to determine clinical diagnosis. The specific patterns of brain glucose metabolism in patients with various types of Parkinsonism were observed and their utility in the differential diagnosis of the disease was analyzed. 18F-FDG PET/CT imaging"diagnostic tree"model was established and its value in the differential diagnosis of Parkinsonism was verified. Results: A total of 320 patients, 187 males and 133 females, aged (62±9) years, were enrolled in our study, including 80 PD, 90 PSP, 114 MSA-C and 36 MSA-P patients. The differential diagnostic features of cerebral glucose metabolism of Parkinsonism were as follows: the metabolism of putamen increased in PD patients, the metabolism of caudate nucleus, thalamus, midbrain, and frontal lobe decreased in PSP patients, the metabolism of cerebellum decreased in MSA-C patients, and the metabolism of putamen and cerebellum decreased in MSA-P patients. The sensitivity and specificity of the"diagnostic tree"model are 88.75% and 91.25% for PD diagnosis, 54.44% and 96.96% for PSP diagnosis, 87.72% and 86.41% for MSA-C diagnosis, and 55.56% and 91.55% for MSA-P diagnosis, respectively. It could correctly classify 75%(240/320) of patients. Conclusions: Characteristic metabolism patterns of brain in 18F-FDG PET/CT imaging is significant for the differential diagnosis of PD, PSP, MSA-C and MSA-P. The"diagnostic tree"model is valuable for clinical diagnosis.

Metformin Ameliorates Postoperative Cognitive Dysfunction through Regulation of the AMPK/SIRT1 Pathway

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common postoperative complication in elderly patients. The purpose of this study was to investigate the mechanism through which metformin improves postoperative cognitive function.

METHODS

In the in vivo experiment, 18-month-old Sprague-Dawley (SD) rats were randomly divided into four groups (n = 12 in each group): the control, metformin, operation, and operation plus metformin groups. The animals were pretreated with metformin by gavage once daily for two weeks. The Morris water maze (MWM) was used to measure cognitive ability. In the in vitro experiment, BV2 cells were divided into five groups: the control, metformin, lipopolysaccharide (LPS), LPS plus metformin, and LPS plus metformin plus compound C groups. We stimulated microglia with LPS (500 ng/mL). Immunofluorescence and Western blotting were used to assess ROS (reactive oxygen species) levels, autophagy-associated protein levels and adenosine monophosphate-activated protein kinase (AMPK)/regulator factor 2-related enzyme 1 (SIRT1) signaling pathway activity in the rat cortex and microglial cells.

RESULTS

In the MWM test, the metformin-pretreated rats spent a higher proportion of time in the target quadrant. Immunofluorescence showed that the fluorescence intensity of LC3 in the cortex was increased in rats pretreated with metformin. Western blotting indicated that metformin upregulated the expression of autophagy-related and AMPK/SIRT1 signaling pathway-related proteins in the cortex after surgery. By activating the AMPK/SIRT1 signaling pathway in vitro, metformin reduced microglial activation and oxidative stress and promoted autophagy.

CONCLUSIONS

Through the AMPK/SIRT1 pathway, metformin can boost autophagy and reduce oxidative stress in cortical microglia in older rats, in turn improving postoperative cognitive function.

Head-to-head comparison of plasma and PET imaging ATN markers in subjects with cognitive complaints

BACKGROUND

Gaining more information about the reciprocal associations between different biomarkers within the ATN (Amyloid/Tau/Neurodegeneration) framework across the Alzheimer's disease (AD) spectrum is clinically relevant. We aimed to conduct a comprehensive head-to-head comparison of plasma and positron emission tomography (PET) ATN biomarkers in subjects with cognitive complaints.

METHODS

A hospital-based cohort of subjects with cognitive complaints with a concurrent blood draw and ATN PET imaging (18F-florbetapir for A, 18F-Florzolotau for T, and 18F-fluorodeoxyglucose [18F-FDG] for N) was enrolled (n = 137). The β-amyloid (Aβ) status (positive versus negative) and the severity of cognitive impairment served as the main outcome measures for assessing biomarker performances.

RESULTS

Plasma phosphorylated tau 181 (p-tau181) level was found to be associated with PET imaging of ATN biomarkers in the entire cohort. Plasma p-tau181 level and PET standardized uptake value ratios of AT biomarkers showed a similarly excellent diagnostic performance for distinguishing between Aβ+ and Aβ- subjects. An increased tau burden and glucose hypometabolism were significantly associated with the severity of cognitive impairment in Aβ+ subjects. Additionally, glucose hypometabolism - along with elevated plasma neurofilament light chain level - was related to more severe cognitive impairment in Aβ- subjects.

CONCLUSION

Plasma p-tau181, as well as 18F-florbetapir and 18F-Florzolotau PET imaging can be considered as interchangeable biomarkers in the assessment of Aβ status in symptomatic stages of AD. 18F-Florzolotau and 18F-FDG PET imaging could serve as biomarkers for the severity of cognitive impairment. Our findings have implications for establishing a roadmap to identifying the most suitable ATN biomarkers for clinical use.

Correlation exploration among CT imaging, pathology and genotype of pulmonary ground-glass opacity

To analyse the clinical features, imaging manifestation, pathological typing and genetic testing results of patients undergoing surgery for ground-glass opacity (GGO) nodules, and explore the reasonable diagnosis and treatment program for GGO patients as to provide the basis for the establishment of GGO treatment process. This study is an exploratory study. 465 cases with GGO confirmed by HRCT, undergoing surgery and approved by pathologic diagnosis in Shanghai pulmonary hospital were enrolled in this study. All the patients with GGO were cases with single lesion. The relationship between the clinical, imaging, pathological and molecular biological data of single GGO were statistically studied. (1) Among 465 cases, the median age was 58 years and females were 315 (67.7%); there were 397 (85.4%) non-smoking, and 354 cases (76.1%) had no clinical symptoms. There were 33 cases of benign and 432 cases of malignant GGO. Significant differences were observed on the size, vacuole sign, pleural indentation and blood vessel sign of GGO between two groups (p < 0.05). Of 230 mGGO, there were no AAH, 13 cases of AIS, 25 cases of MIA and 173 cases of invasive adenocarcinoma. The probability of solid nodules in invasive adenocarcinoma was higher than that in micro invasive carcinoma, and the difference was statistically significant (p < 0.05). 360 cases were followed up with the average follow-up time of 6.05 months, and GGO of 34 cases (9.4%) increased. (2) In 428 adenocarcinoma samples approved by pathologic diagnosis, there were 262 (61.2%) lesions of EGFR mutation, 14 (3.3%) lesions of KRAS mutation, 1 (0.2%) lesion of Braf mutation, 9 (2.1%) lesions of EML4-ALK gene fusion and 2 (0.5%) lesions of ROS1 fusion. The detection rate of gene mutation in mGGO was higher than that of pGGO. During the follow-up period, genetic testing results of 32 GGO showed that EGFR mutation rate was 53.1%, ALK positive rate of 6.3%, KRAS mutation rate of 3.1% and no ros1 and BRAF gene mutation. No statistically significant difference was observed in comparison with unchanged GGO. (3) EGFR mutation rate of invasive adenocarcinoma was the highest (168/228, 73.7%), mainly in the 19Del and L858R point mutations. No KRAS mutation was found in atypical adenoma hyperplasia. No significant difference was observed on the mutation rate of KRAS between different types of GGO (p = 0.811). EML4-ALK fusion gene was mainly detected in invasive adenocarcinoma (7/9). GGO tends to occur in young, non-smoking women. The size of GGO is related to the degree of malignancy. Pleural depression sign, vacuole sign and vascular cluster sign are all characteristic images of malignant GGO. pGGO and mGGO reflect the pathological development of GGO. During the follow-up, it is found that GGO increases and solid components appear, which is the indication of surgical resection. The detection rate of EGFR mutations in mGGO and invasive adenocarcinoma is high. pGGO has heterogeneity in imaging, pathology and molecular biology. Heterogeneity research helps to formulate correct individualized diagnosis and treatment plans.

Fibroblast growth factor 21 attenuates ventilator-induced lung injury by inhibiting the NLRP3/caspase-1/GSDMD pyroptotic pathway

BACKGROUND

Ventilator-induced lung injury (VILI) is caused by overdistension of the alveoli by the repetitive recruitment and derecruitment of alveolar units. This study aims to investigate the potential role and mechanism of fibroblast growth factor 21 (FGF21), a metabolic regulator secreted by the liver, in VILI development.

METHODS

Serum FGF21 concentrations were determined in patients undergoing mechanical ventilation during general anesthesia and in a mouse VILI model. Lung injury was compared between FGF21-knockout (KO) mice and wild-type (WT) mice. Recombinant FGF21 was administrated in vivo and in vitro to determine its therapeutic effect.

RESULTS

Serum FGF21 levels in patients and mice with VILI were significantly higher than in those without VILI. Additionally, the increment of serum FGF21 in anesthesia patients was positively correlated with the duration of ventilation. VILI was aggravated in FGF21-KO mice compared with WT mice. Conversely, the administration of FGF21 alleviated VILI in both mouse and cell models. FGF21 reduced Caspase-1 activity, suppressed the mRNA levels of Nlrp3, Asc, Il-1β, Il-18, Hmgb1 and Nf-κb, and decreased the protein levels of NLRP3, ASC, IL-1β, IL-18, HMGB1 and the cleaved form of GSDMD.

CONCLUSIONS

Our findings reveal that endogenous FGF21 signaling is triggered in response to VILI, which protects against VILI by inhibiting the NLRP3/Caspase-1/GSDMD pyroptosis pathway. These results suggest that boosting endogenous FGF21 or the administration of recombinant FGF21 could be promising therapeutic strategies for the treatment of VILI during anesthesia or critical care.