Pyruvate dehydrogenase kinase 1 protects against neuronal injury and memory loss in mouse models of diabetes.

Hyperglycemia-induced aberrant glucose metabolism is a causative factor of neurodegeneration and cognitive impairment in diabetes mellitus (DM) patients. The pyruvate dehydrogenase kinase (PDK)-lactic acid axis is regarded as a critical link between metabolic reprogramming and the pathogenic process of neurological disorders. However, its role in diabetic neuropathy remains unclear. Here, we found that PDK1 and phosphorylation of pyruvate dehydrogenase (PDH) were obviously increased in high glucose (HG)-stimulated primary neurons and Neuro-2a cell line. Acetyl-coA, a central metabolic intermediate, might enhance PDK1 expression via histone H3K9 acetylation modification in HG condition. The epigenetic regulation of PDK1 expression provided an available negative feedback pattern in response to HG environment-triggered mitochondrial metabolic overload. However, neuronal PDK1 was decreased in the hippocampus of streptozotocin (STZ)-induced diabetic mice. Our data showed that the expression of PDK1 also depended on the hypoxia-inducible factor-1 (HIF-1) transcriptional activation under the HG condition. However, HIF-1 was significantly reduced in the hippocampus of diabetic mice, which might explain the opposite expression of PDK1 in vivo. Importantly, overexpression of PDK1 reduced HG-induced reactive oxygen species (ROS) generation and neuronal apoptosis. Enhancing PDK1 expression in the hippocampus ameliorated STZ-induced cognitive impairment and neuronal degeneration in mice. Together, our study demonstrated that both acetyl-coA-induced histone acetylation and HIF-1 are necessary to direct PDK1 expression, and enhancing PDK1 may have a protective effect on cognitive recovery in diabetic mice. Schematic representation of the protective effect of PDK1 on hyperglycemia-induced neuronal injury and memory loss. High glucose enhanced the expression of PDK1 in an acetyl-coA-dependent histone acetylation modification to avoid mitochondrial metabolic overload and ROS release. However, the decrease of HIF-1 may impair the upregulation of PDK1 under hyperglycemia condition. Overexpression of PDK1 prevented hyperglycemia-induced hippocampal neuronal injury and memory loss in diabetic mice.

Acyl-protein thioesterase1 alleviates senile osteoporosis by promoting osteoblast differentiation via depalmitoylation of BMPR1a.

Objective: Senile osteoporosis (SOP) is an aging-related disease. The depalmitoylating enzyme Acyl-protein thiesterase1 (APT1) is involved in disease regulation. This study explored the mechanism of APT1 in SOP. Methods: Eight-week-old SAMP6 mice were selected as SOP models and SAMR1 mice were controls, while osteoblasts were isolated from the femoral surface-soft tissues of SOP and control mice as in vitro models. Mouse femur morphological, bone mineral density (BMD), femur maximum elastic stress and maximum load, and APT1 expression were detected by HE staining, X-ray bone densitometer, material testing machine, and RT-qPCR and Western blot (WB). Osteoprotegrin (OPG)-labeled osteoblasts and APT1 localization in bone tissues were detected by immunohistochemical staining. APT1 expression was promoted in SOP mice by tail vein injection of APT1 lentivirus or promoted/silenced in osteoblasts by transfection of pcDNA3.1-APT1 overexpression or si-APT1 plasmids. SOP mouse osteoblast differentiation (OD), OD-related protein levels, osteoblast proliferation, BMPR1a palmitoylation level, and BMP/Smad pathway were detected by alizarin red staining, ALP activity detection, WB, CCK-8, and IP-ABE method. The effects of the pathway inhibitor LDN-193189 on OD were detected. Results: APT1 was under-expressed in osteoblasts of bone tissue in SOP mice and mainly localized in osteoblasts. SOP mice manifested increased bone marrow cavity and bone trabecular space, thinned trabecular bone, decreased BMD, maximum elastic stress, maximum load, and reduced OPG-positive osteoblasts in bone tissues, which were averted by APT1 overexpression, thus alleviating SOP. APT1 overexpression increased osteoblast calcium nodules, ALP activity, OD-related protein levels, and cell proliferation. In mechanism, APT1 overexpression inhibited BMPR1a palmitoylation in SOP mouse osteoblasts and activated the BMP/Smad pathway, thus promoting OD. Conclusion: APT1 activated the BMP/Smad pathway and promoted OD by regulating BMPR1a depalmitoylation, thus alleviating mouse SOP.

Effect of hyperlipidaemia to accelerate intervertebral disc degeneration in the injured rat caudal disc model.

BACKGROUND: Dyslipidaemia is a well-known risk factor for the development of atherosclerosis, however, little is known about the effect of dyslipidaemia on intervertebral disc degeneration (IVDD). Thus, the purpose of this study is to investigate the relationship between dyslipidaemia and IVDD, and to identify the possible mechanism by which dyslipidaemia aggravates the degeneration of intervertebral discs. METHODS: Hyperlipidaemia rats were induced, thirty male Wistar rats were randomly divided into two groups: normal chow diet control group (CON) and high-fat diet group (HFD) for 8 weeks. And then, a rat disc degeneration model was established, rats were divided into three experimental groups: the normal chow diet + sham surgery group (CON-Sham); the normal chow diet + needle puncture group (CON-NP); and the high-fat diet + needle puncture group (HFD-NP), all rats were continually fed with normal chow diet or HFD 8 weeks. At the end of the experiment, the discs were harvested and histomorphological analysis, immunohistochemistry staining, real-time PCR and western blot were performed for all groups. RESULTS: The degenerative histological score of disc in the HFD-NP group was significantly higher than the CON-NP group. Immunohistochemical analysis revealed remarkable reductions in aggrecan and collagen type II expressions, and significant increases in IL-1ß, TNF-α, MMP-13, HIF-1α and P65 expression in the HFD-NP group. RT-PCR and western blot analysis showed that the mRNA levels and protein expressions of MMP-13 and TIMP-1 were higher in the HFD-NP group. CONCLUSIONS: Hyperlipidaemia resulted in an exaggerated degenerative changes and altered expression and transcription of the degeneration-associated molecules in the rat disc tissue. These results raise the possibility that hyperlipidaemia may accelerate the progression of disc degeneration.

Follistatin-like protein 1 promotes inflammatory reactions in nucleus pulposus cells by interacting with the MAPK and NFκB signaling pathways.

OBJECTIVE: Follistatin-like protein 1 (FSTL1) is a well-known mediator of inflammation. Intervertebral disc disease is an inflammatory disorder. Here, we investigated the role of FSTL1 in the intervertebral discs inflammation. METHODS: Expression of FSTL1 in nucleus pulposus tissues from rats and human was determined by immunohistochemistry staining and western blot analysis. The expression levels of tumor necrosis factor-α (TNF-α), interleukin1-ß (IL-1ß) and matrix metalloproteinase 13 (MMP-13) in human and rat nucleus pulposus tissues were measured by immunohistochemistry staining. The mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NFκB) signaling pathways were detected by western blotting. RESULTS: FSTL1 serum levels were significantly increased in lumbar disc herniation patients and had a positive correlation with Visual Analogue Scores. Additionally, FSTL1 expression was significantly increased in extrusion group compared with protrusion and control groups. Furthermore, FSTL1 expression was significantly increased in intervertebral disc degeneration models of rats. Immunohistochemistry staining demonstrated that the levels of TNF-α, IL-1ß and MMP-13 were increased in the pathogenesis of intervertebral disc disease. Recombinant human FSTL1 significantly increased the production of proinflammatory cytokines in vitro. In addition, FSTL1 promoted inflammation by activating c-Jun N-terminal kinase (JNK), extracellular regulated protein kinases 1/2(ERK1/2) and NFκB signaling. CONCLUSIONS: These data imply that FSTL1 expression was increased in the pathogenesis of intervertebral disc disease. Importantly, FSTL1 promoted inflammatory catabolism in the nucleus pulposus by activating JNK, ERK 1/2/MAPK and NFκB signaling.

Progranulin Protects Against Osteonecrosis of the Femoral Head by Activating ERK1/2 Pathway.

The aim of this study was to investigate progranulin (PGRN) expression and its effect in cartilage degradation and in the pathogenesis of osteonecrosis of the femoral head (ONFH). Cartilage specimens were obtained from ONFH and FNF patients and PGRN expression was analyzed by immunohistochemistry, western blot analysis, and RT-PCR. Peripheral blood PGRN level was detected by ELISA. Additionally, primary chondrocytes were cultured and treated with PGRN. Next, the expression of aggrecan and collagen II and the activation of ERK1/2 were detected. We observed that the expression of PGRN was significantly upregulated in ONFH patients' articular cartilage, and recombinant PGRN could promote expression of aggrecan and collagen II and the activation of ERK1/2. Collectively, PGRN can improve chondrocyte anabolism and perform a therapeutic role in the pathogenesis of ONFH. This study helps to elucidate the pathogenesis of ONFH and presents PGRN as a potential target for the treatment of ONFH.

Follistatin-like protein 1 suppressed pro-inflammatory cytokines expression during neuroinflammation induced by lipopolysaccharide.

Follistain-like protein 1 (FSTL1), has been recently demonstrated to be involved in the embryo development of nervous system and glioblastoma. However, the role of FSTL1 in neuroinflammation remains unexplored. In this study, the expression of FSTL1 in astrocytes was verified and its role was studied in neuroinflammation induced by in vivo intracerebroventricular (ICV) injection of lipopolysaccharide (LPS) or LPS treatment to astrocytes in vitro. FSTL1 was significantly induced after ICV LPS injection or LPS treatment. FSTL1 suppressed upregulation of pro-inflammatory cytokines in astrocytes after LPS treatment. Moreover, FSTL1 downregulated expression of pro-inflammatory cytokines through suppressing MAPK/p-ERK1/2 pathway in astrocytes. Our results suggest that FSTL1 may play an anti-inflammatory role in neuroinflammation mediated by astrocytes.

Th17 cell frequency and IL-17 concentration correlate with pre- and postoperative pain sensation in patients with intervertebral disk degeneration.

Numerous studies have revealed the presence of T helper 17 (Th17) cells in pathologic intervertebral disk (IVD) tissues and the contribution of Th17-associated cytokines to the development of this disease. However, the pre- and postoperative changes in the proportion of Th17 cells and the concentration of IL-17 in the peripheral blood of patients with IVD degeneration are not clear. The levels of Th17 frequency and the interleukin-17 (IL-17) concentration in peripheral blood from patients and volunteers were examined by flow cytometry and by enzyme-linked immunosorbent assay (ELISA), respectively. The clinical results were evaluated using the visual analogue scale (VAS). These results were subjected to a correlation analysis. Compared with the normal controls, the proportion of Th17 cells and the concentration of IL-17 were significantly increased preoperatively in patients with IVD degeneration. Postoperatively, the levels of Th17 cells and the expression of IL-17 were dramatically decreased. The correlation analysis of the VAS pain scores, Th17 cell frequency, and IL-17 concentration, including the pre- and postoperative levels and the changes induced by the surgery, revealed a positive correlation. The authors' results explain the contribution of Th17 cells and IL-17 to the pain sensation experienced by patients with IVD degeneration. These 2 factors may be good indicators for the evaluation of the surgical outcome of patients with lumbar disk herniation.

Effect comparison of different formulation of Dang-Gui-Bu-Xu-Tang on myelosuppression mouse.

OBJECTIVE: To compare effect of different formulation of Dang-Gui-Bu-Xu-Tang(DGBXT) on myelosuppression mouse. METHODS: HPLC was used to measure active ingredients of two DGBXT formulations. Hemopoesic function of bone marrow was measured by hemopoietic progenitor cell culture and peipheral blood count. And hemopoietic factors in bone marrow were tested by ELISA. RESULTS: The content level of astragaloside A in granule formulation was higher than that in decoction and the content ratio of active ingredient was close to 5 : 1. Two DGBXD formulations could significantly improve amount of peripheral blood cells, and bone marrow cells of bone marrow suppression mice (P<0.05). DGBXD granule formulation significantly increased the colony quantity of all progenitor cell lines and amount of G(2)/M and S phase cells (P<0.05). It also significantly decreased amount of G(0)/G(1) phase cells in the bone marrow and was more effective (P<0.05). CONCLUSIONS: DGBXT decoction and the granule formulation all can improve the hematopoietic function of bone marrow suppression mouse. They can improve quantities of peripheral blood and nucleated bone marrow cells, and yield of the hematopoietic stem/progenitor cells in vitro colony; balance the expression of cytokine (EPO, TPO and GM-CSF) in bone marrow microenvirement. They can also facilitate hematopoietic stem/progenitor cells to enter the cell cycle. And the effect of granule formulation is more satisfactory.