Search

Objective Growing evidence indicates that the activation of c-Jun N-terminal kinase (JNK) is implicated in the multiple major pathological features of Alzheimer disease (AD). However, whether specific inhibition of JNK activation could prevent disease progression in adult transgenic AD models at moderate stage remains unknown. Here we first investigated the potential disease-modifying therapeutic effect of systemic administration of SP600125, a small-molecule JNK-specific inhibitor, in middle-aged APPswe/PS1dE9 mice. Methods Using behavioral, histological, and biochemical methods, outcomes of SP600125 treatment on neuropathology and cognitive deficits were studied in APPswe/PS1dE9 mice. Results Compared with vehicle-treated APPswe/PS1dE9 mice, chronic treatment of SP600125 for 12 weeks potently inhibited JNK activation, which resulted in a marked improvement of behavioral measures of cognitive deficits and a dramatic reduction in amyloid plaque burden, β-amyloid production, tau hyperphosphorylation, inflammatory responses, and synaptic loss in these transgenic animals. In particular, we found that SP600125 treatment strongly promoted nonamyloidogenic amyloid precursor protein (APP) processing and inhibited amyloidogenic APP processing via regulating APP-cleavage secretase expression (ie, ADAM10, BACE1, and PS1) in APPswe/PS1dE9 mice. Interpretation Our findings demonstrate that chronic SP600125 treatment is powerfully effective in slowing down disease progression by markedly reducing multiple pathological features and ameliorating cognitive deficits associated with AD. This study highlights the concept that active JNK actually contributes to the development of the disease, and provides critical preclinical evidence that specific inhibition of JNK activation by SP600125 treatment may be a novel promising disease-modifying therapeutic strategy for the treatment of AD. Ann Neurol 2015;77:637-654 [ABSTRACT FROM AUTHOR]

The aggregation of soluble amyloid-beta (Aβ) peptide into oligomers/fibrils is one of the key pathological features in Alzheimer's disease (AD). The Aβ aggregates are considered to play a pivotal role in the pathogenesis of AD. Therefore, inhibiting Aβ aggregation and destabilizing preformed Aβ fibrils would be an attractive therapeutic target for prevention and treatment of AD. S14G-humanin (HNG), a synthetic derivative of Humanin (HN), has been shown to be a strong neuroprotective agent against various AD-related insults. Recent studies have shown that HNG can significantly improve cognitive deficits and reduce insoluble Aβ levels as well as amyloid plaque burden without affecting amyloid precursor protein processing and Aβ production in transgenic AD models. However, the potential mechanisms by which HNG reduces Aβ-related pathology in vivo remain obscure. In the present study, we found that HNG could significantly inhibit monomeric Aβ1-42 aggregation into fibrils and destabilize preformed Aβ1-42 fibrils in a concentration-dependent manner by Thioflavin T fluorescence assay. In transmission electron microscope study, we observed that HNG was effective in inhibiting Aβ1-42 fibril formation and disrupting preformed Aβ1-42 fibrils, exhibiting various types of amorphous aggregates without identifiable Aβ fibrils. Furthermore, HNG-treated monomeric or fibrillar Aβ1-42 was found to significantly reduce Aβ1-42-mediated cytotoxic effects on PC12 cells in a dose-dependent manner by MTT assay. Collectively, our results demonstrate for the first time that HNG not only inhibits Aβ1-42 fibril formation but also disaggregates preformed Aβ1-42 fibrils, which provides the novel evidence that HNG may have anti-Aβ aggregation and fibrillogenesis, and fibril-destabilizing properties. Together with previous studies, we concluded that HNG may have promising therapeutic potential as a multitarget agent for the prevention and/or treatment of AD. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Cerebral amyloid-beta protein (Aβ) deposition and associated neuroinflammation and apoptosis are increasingly recognized as an important component leading to cognitive impairment in Alzheimer’s disease (AD). Humanin (HN) and its derivative, S14G-HN (HNG), are best known for their ability to suppress neuronal death induced by AD-related insults in vitro. Furthermore, limited in vivo studies show that HNG can ameliorate memory impairment induced by intracerebroventricular injection of anti-cholinergic drugs or Aβ25-35. However, the mechanism underlying the in vivo effect remains unclear. In this study, we sought to determine the effects of HNG on neuroinflammatory responses and apoptosis associated with behavioral deficits induced by Aβ25-35 in vivo. Our results indicate that intracerebroventricular injection of aggregated Aβ25-35 induced impairment of learning and memory, markedly elevated numbers of reactive astrocytes, activated microglia, and apoptotic cells, as well as remarkable increased levels of IL-6 and TNFα. Moreover, intraperitoneal HNG treatment ameliorated behavioral deficits, and reduced neuroinflammatory responses and apoptotic cells in the brain. Cumulatively, these finding demonstrate for the first time that HNG may have the potential for attenuating Aβ-induced cognitive deficits by reducing inflammatory responses and apoptosis in vivo, which may add to the novel evidence for anti-inflammatory and antiapoptosis properties of HNG in AD treatment. [Copyright &y& Elsevier]

Abstract: Increased accumulation of amyloid-beta peptide (Aβ) and neuroinflammation is known to exist within the Alzheimer''s disease (AD) brain. However, it remains unclear which form of Aβ pathologies triggers neuroinflammation and whether increased neuroinflammation contributes to cognitive deficits in AD. In the present study we found that increased inflammatory responses might occur early in preplaque APPswe/PS1dE9 mice, and were significantly enhanced in both early- and late-plaque APPswe/PS1dE9 mice. Correlational analysis revealed that multiple inflammatory indexes significantly correlated with soluble Aβ level, rather than amyloid plaque burden or insoluble Aβ level, in APPswe/PS1dE9 mice. Moreover, multiple inflammatory indexes highly correlated with the impaired spatial learning and memory in APPswe/PS1dE9 mice. Collectively, these results provide evidence that inflammatory responses might be likely triggered by soluble toxic Aβ species. Importantly, we demonstrate for the first time that multiple inflammatory pathways might be involved in the development and progression of cognitive deficits in APPswe/PS1dE9 mice, suggesting that a pharmacological approach targeting multiple inflammatory pathways may be a novel promising strategy to prevent or delay AD. [Copyright &y& Elsevier]

Background: Thymectomy is an efficient and standard treatment strategy for patients with myasthenia gravis (MG), postoperative myasthenic crisis (POMC) is the major complication related to thymectomy and has a strongly life-threatening effect. As a biomarker, whether the bilirubin level is a risk factor for MG progression remains unclear. This study aimed to investigate the association between the preoperative bilirubin level and postoperative myasthenic crisis (POMC)., Methods: We analyzed 375 patients with MG who underwent thymectomy at Tangdu Hospital between January 2012 and September 2021. The primary outcome measurement was POMC. The association between POMC and bilirubin level was analyzed by restricted cubic spline (RCS). Indirect bilirubin (IBIL) was divided into two subgroups based on the normal upper limit of IBIL, 14 μmol/L., Results: Compared with non-POMC group, IBIL levels were significantly higher in patients with POMC. Elevated IBIL levels were closely associated with an increased risk of POMC ( p for trend = 0.002). There was a dose-response curve relationship between IBIL levels and POMC incidence ( p for non-linearity = 0.93). However, DBIL levels showed a U-shaped association with POMC incidence. High IBIL level (≥14 μmol/L) was an independent predictive factor for POMC [odds ratio = 3.47, 95% confidence interval (CI): 1.56-7.8, p = 0.002]. The addition of high IBIL levels improved the prediction model performance (net reclassification index = 0.186, 95% CI: 0.039-0.334; integrated discrimination improvement = 0.0345, 95% CI: 0.005-0.065)., Conclusion: High preoperative IBIL levels, especially those exceeding the normal upper limit, could independently predict the incidence of POMC., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Sun, Ruan, Zhang, Guo, Li, Wang, Gao, Tang, Song, Hao, Huang, Li, Ning, Su, Lu, Wang, Cao, Li and Chang.)

Objective To study the effects of dopamine receptor D2 (DRD2) on the adipogenesis genes in mouse primary mesencephalic neurons. Methods The lentiviral vectors which expressed specific shRNA targeting DRD2 were constructed to decrease DRD2 expression in mouse primary mesencephalic neurons. High throughput sequencing (HTS) analysis was used to investigate gene expression changes between the DRD2 knock-down group and the negative control group. Real-time quantitative PCR (qRT-PCR) and Western blot analysis were applied to verify the differently expressed genes. Fatty acids were measured by fatty acid detection kit. Results DRD2 expression was effectively down-regulated in mouse primary mesencephalic neurons by lentiviral vectors. HTS revealed adipogenesis genes were significantly up-regulated after DRD2 down-regulation, mainly including delta(14)-sterol reductase, acetyl-coenzyme A synthetase, insulin-induced gene 1 protein and especially stearoyl-coenzyme A desaturase 1 (SCD1, 4-fold upregulated). The qRT-PCR and Western blot analysis verified that SCD1 was upregulated 2.6 folds and 2 folds respectively by lentiviral DRD2-shRNA vectors. Moreover, the SCD1-related free fatty acids were significantly more increased than the negative control group. Conclusion DRD2 in primary mesencephalic neurons had a significant regulative effect on the adipogenesis genes. The up-regulation of SCD1 can accelerate the conversion of saturated fatty acids to monounsaturated fatty acids and prevent the damage of lipid toxicity to cells.

Objective: To explore the change in the number and role of Gr-1⁺ CD11b⁺ myeloid-derived suppressor cells (MDSCs) in experimental autoimmune encephalomyelitis (EAE)., Methods: Totally 30 healthy female C57BL/6 mice were randomly divided into two groups: EAE-induced group (n=15) and control group (n=15). EAE was induced by immunization with myelin oligodendrocyte glycoprotein peptide 35-55 (MOG35-55), and pathological changes in spinal cords were revealed by HE staining and Luxol fast blue (LFB) staining. The number of Gr-1⁺ CD11b⁺ MDSCs in spleens and spinal cords of the two groups was respectively compared by flow cytometry and immunofluorescent staining. The effect of Gr-1⁺ CD11b⁺ MDSCs from EAE mice on the proliferation of CD4⁺ T cells and CD8⁺ T cells was evaluated by in vitro co-culture system., Results: Twelve of 15 immunized mice (80%) developed EAE. HE staining showed an extensive infiltration of inflammatory cells in the spinal cords of the EAE mice. LFB staining revealed multiple demyelinated lesions in the above inflammatory infiltration. The immunofluorescent histochemistry suggested that many Gr-1⁺ CD11b⁺ MDSCs were present in spinal cords of the EAE mice, but no positive cells were observed in the control group. The mass of spleen in the EAE mice was significantly higher than that of the control mice [(146.5 ± 12.4) mg vs (67.2 ± 8.7) mg, P<0.01], and the proportion of splenic Gr-1⁺ CD11b⁺ MDSCs in EAE mice significantly increased (P<0.01 vs controls). Consistent with the results of immunofluorescent staining, a significantly increased proportion of Gr-1⁺ CD11b⁺ MDSCs in spinal cords of EAE mice was observed with flow cytometry. In vitro co-culture analysis revealed that Gr-1⁺ CD11b⁺ MDSCs from spinal cords of the EAE mice markedly suppressed the proliferation of CD4⁺ T cells and CD8⁺ T cells., Conclusion: EAE induces an expansion and aggregation of Gr-1⁺ CD11b⁺ MDSCs in spleens and spinal cords. These cells suppress T cell proliferation in vitro and are involved in the immunoregulation of EAE.

Introduction: Human myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular system. Experimental autoimmune myasthenia gravis (EAMG) is a well-established animal model for MG that can be induced by active immunization with the Torpedo californica-derived acetylcholine receptor (AChR). Due to the expensive cost of purifying AChR from Torpedo californica, the development of an easier and more economical way of inducing EAMG remains critically needed., Material and Methods: Full-length cDNA of the human skeletal muscle AChR α1 subunit was obtained from TE671 cells. The DNA fragment encoding the extracellular domain (ECD) was then amplified by polymerase chain reaction (PCR) and inserted into pET-16b. The reconstructed plasmid was transformed into the host strain BL21(DE3)pLysS, which was derived from Escherichia coli. Isopropyl-β-D-thiogalactopyranoside (IPTG) was used to induce the expression of the N-terminal ECD. The produced protein was purified with immobilized Ni(2+) affinity chromatography and refolded by dialysis., Results: The recombinant protein was efficiently refolded to soluble active protein, which was verified by ELISA. After immunization with the recombinant ECD, all rats acquired clinical signs of EAMG. The titer of AChR antibodies in the serum was significantly higher in the EAMG group than in the control group, indicating successful induction of EAMG., Conclusions: We describe an improved procedure for refolding recombinant ECD of human muscle AChR. This improvement allows for the generation of large quantities of correctly folded recombinant ECD of human muscle AChR, which provides for an easier and more economical way of inducing the animal model of MG.

Objective: To investigate the feature and regularity of the collagen change in bone healing during bone lengthening., Methods: Bone lengthening model was made in the middle segment of the rabbit tibia. Five days after the model was established, the bone was lengthened 1.5 mm per day for 14 days. The rabbits were put to death after elongation, 7, 14, 21, 30, 40, 50, 60 and 70 days after elongation. The distracted area of the bone was imbedded with paraffin. After being stained by the picric acid-sirius red staining, the slice was observed under polarized microscope., Results: The features of the collagen change in the distracted bone were as follows: (1) In the fibrous tissue of the distracted area during lengthening period and the early stage after lengthening, there was not only collagen III but also much collagen I. (2) Collagen I , II and III were observed in the cartilage. (3) Collagen I, II and III were also observed in the pseudo-growth plate. (4) Collagen I took the dominance during lengthening period and the late stage after lengthening., Conclusion: New bone formation in bone lengthening is under the distracted force, so the collagen changes have different features compared with that in fracture healing. Collagen I, II and III can be identified by picric acid-sirius red staining and polarized microscope, so a new method for studying the collagen typing in bone repairing is provided.