The role of carbonic anhydrase III and autophagy in type 2 diabetes with cardio-cerebrovascular disease.

Type 2 diabetes mellitus (T2DM) is one of the most common chronic diseases among the elderly people. The T2DM increases the risk of cardio-cerebrovascular disease (CCD), and the main pathological change of the CCD is atherosclerosis (AS). Meanwhile, the carbonic anhydrases (CAs) are involved in the formation and progression of plaques in AS. However, the exact physiological mechanism of carbonic anhydrase III (CAIII) has not been clear yet, and there are also no correlation study between CAIII protein and T2DM with CCD. The 8-week old diabetic mice (db/db-/- mice) and wild-type mice (wt mice) were feed by a normal diet till 32 weeks, and detected the carotid artery vascular opening angle using the method of biomechanics; The changes of cerebral cortex and myocardium were watched by the ultrastructure, and the autophagy were observed by electron microscope; The tissue structure, inflammation and cell injury were observed by Hematoxylin and eosin (HE) staining; The apoptosis of cells were observed by TUNEL staining; The protein levels of CAIII, IL-17, p53 were detected by immunohistochemical and Western Blot, and the Beclin-1, LC3, NF-κB were detected by Western Blot. All statistical analysis is performed using PRISM software. Compared with wt mice, db/db-/- mice' carotid artery open angle increased significantly. Electron microscope results indicated that autophagy in db/db-/- mice cerebral cortex and heart tissue decreased and intracellular organelle ultrastructure were damaged. HE staining indicated that, db/db-/- mice' cerebral cortex and heart tissue stained lighter, inflammatory cells infiltration, cell edema were obvious, myocardial fibers were disorder, and myocardial cells showed different degrees of degeneration. Compared with wt mice, TUNEL staining showed that there was obviously increase in db/db-/- mice cortex and heart tissue cell apoptosis. The results of immunohistochemistry and Western Blot indicated that CAIII, Beclin-1 and LC3II/I expression levels conspicuously decreased in cortex and heart tissue of db/db-/- mice, and the expression level of IL-17, NF-κB and p53 obviously increased. The carotid artery' vascular stiffness was increased and which was probably related with formation of AS in diabetic mice. And the autophagy participated in the occurrence and development of diabetic CCD. CAIII protein might somehow be involved in the regulation of autophagy probably through affecting cell apoptosis and inflammation, but the underlying mechanism remains to be further studied.

IP3R-Grp75-VDAC1-MCU calcium regulation axis antagonists protect podocytes from apoptosis and decrease proteinuria in an Adriamycin nephropathy rat model.

BACKGROUND: The mechanism of podocyte apoptosis is not fully understood. In addition, the role of the inositol 1,4,5-triphosphate receptor (IP3R)/glucose-regulated protein 75 (Grp75)/voltage-dependent anion channel 1 (VDAC1)/mitochondrial calcium uniporter (MCU) calcium regulation axis, which is located at sites of endoplasmic reticulum (ER) mitochondria coupling, in the mechanism of podocyte apoptosis is unclear. This study aimed to understand the roles of this axis in podocyte apoptosis and explore potential targets for podocyte protection. METHODS: The expression of IP3R, Grp75, VDAC1, and MCU and mitochondrial Ca2+ were analyzed during Adriamycin- or angiotensin II-induced apoptosis in cultured mouse podocytes. The interaction between IP3R, Grp75, and VDAC1 was investigated using co-immunoprecipitation experiments. The effects of IP3R, Grp75, and MCU agonists and antagonists on mitochondrial Ca2+ and apoptosis were investigated in cultured podocytes. The podocyte-protective effects of an MCU inhibitor were further investigated in rats with Adriamycin-induced nephropathy. RESULTS: Increased expression of IP3R, Grp75, VDAC1 and MCU, enhanced interaction among the IP3R-Grp75-VDAC1 complex, mitochondrial Ca2+ overload, and increased active caspase-3 levels were confirmed during Adriamycin- or angiotensin II-induced mouse podocyte apoptosis. Agonists of this axis facilitated mitochondrial Ca2+ overload and podocyte apoptosis, whereas specific antagonists against IP3R, Grp75, or MCU prevented mitochondrial Ca2+ overload and podocyte apoptosis. A specific MCU inhibitor prevented Adriamycin-induced proteinuria and podocyte foot process effacement in rats. CONCLUSIONS: This study identified a novel pathway in which the IP3R-Grp75-VDAC1-MCU calcium regulation axis mediated podocyte apoptosis by facilitating mitochondrial Ca2+ overload. Antagonists that inhibit Ca2+ transfer from ER to mitochondria protected mouse podocytes from apoptosis. An MCU inhibitor protected podocytes and decreased proteinuria in rats with Adriamycin-induced nephropathy. Therefore, antagonists to this pathway have promise as novel podocyte-protective drugs.

EGb761 improves the cognitive function of elderly db/db-/- diabetic mice by regulating the beclin-1 and NF-κB signaling pathways.

To assess whether EGb761 could protect elderly diabetic mice with cognitive disorders and explore the role of beclin-1-mediated autophagy in these protective effects. Two-month-old male db/db-/- mice and wild-type C57/BL6 mice were randomly divided into six groups: db/db-/- control, db/db-/- 50 mg, db/db-/- 100 mg, wild-type (WT) control, WT 50 mg, and WT 100 mg. EGb761 (50 mg/kg or 100 mg/kg of bodyweight) was given by gavage once a day for 1 month from the age of 6 months. Y-maze and social choice tests were performed at 8th months. The blood pressure was measured. The imaging changes in the brain were measured using magnetic resonance imaging (MRI). The expression and distribution of beclin-1, LC3, and NF-κB were detected using immunohistochemistry staining and western blotting. Ultrastructure alterations in the hippocampus were observed using transmission electron microscopy. Compared with WT mice, the learning ability, memory and overall cognitive function of db/db-/- mice decreased (P < 0.05), and EGb761 could significantly improve the learning and memory function of db/db-/- mice (P < 0.05). EGb761 significantly improved systolic blood pressure in db/db-/- mice (P < 0.01). In addition, fMRI-bold showed a decline in the hippocampus of mice in the db/db-/- group compared with WT. EGb761 could improve these above changes. Immunohistochemistry staining and western blotting confirmed that EGb761 significantly increased beclin-1 and reduced LC3-II/I levels in the brains of db/db-/- mice (P < 0.05). NF-κB levels were obviously higher in the db/db-/- group than that in the WT group, and EGb761 significantly reduced NF-κB levels in db/db-/- mice (P < 0.05). There was a trend of increased autophagosomes in db/db-/- mice, but EGb761 did not change obviously the number of autophagosomes. Compared with normal aged WT mice, aging db/db-/- mice had more common complications of cerebral small vessel disease and cognitive dysfunction. EGb761 could significantly improve the cognitive function of aging db/db-/- mice via a mechanism that may involve the regulation of beclin-1, LC3, and NF-κB.

A novel palmitic acid hydroxy stearic acid (5-PAHSA) plays a neuroprotective role by inhibiting phosphorylation of the m-TOR-ULK1 pathway and regulating autophagy.

AIMS: Type 2 diabetes mellitus (T2DM) can lead to brain dysfunction and a series of neurological complications. Previous research demonstrated that a novel palmitic acid (5-PAHSA) exerts effect on glucose tolerance and chronic inflammation. Autophagy was important in diabetic-related neurodegeneration. The aim of the present study was to investigate whether 5-PAHSA has specific therapeutic effects on neurological dysfunction in diabetics, particularly with regard to autophagy. METHODS: 5-PAHSA was successfully synthesized according to a previously described protocol. We then carried out a series of in vitro and in vivo experiments using PC12 cells under diabetic conditions, and DB/DB mice, respectively. PC12 cells were treated with 5-PAHSA for 24 h, while mice were administered with 5-PAHSA for 30 days. At the end of each experiment, we analyzed glucolipid metabolism, autophagy, apoptosis, oxidative stress, cognition, and a range of inflammatory factors. RESULTS: Although there was no significant improvement in glucose metabolism in mice administered with 5-PAHSA, ox-LDL decreased significantly following the administration of 5-PAHSA in serum of DB/DB mice (p < 0.0001). We also found that the phosphorylation of m-TOR and ULK-1 was suppressed in both PC12 cells and DB/DB mice following the administration of 5-PAHSA (p < 0.05 and p < 0.01), although increased levels of autophagy were only observed in vitro (p < 0.05). Following the administration of 5-PAHSA, the concentration of ROS decreased in PC12 cells and the levels of CRP increased in high-dose group of 5-PAHSA (p < 0.01). There were no significant changes in terms of apoptosis, other inflammatory factors, or cognition in DB/DB mice following the administration of 5-PAHSA. CONCLUSION: We found that 5-PAHSA can enhance autophagy in PC12 cells under diabetic conditions. Our data demonstrated that 5-PAHSA inhibits phosphorylation of the m-TOR-ULK1 pathway and suppressed oxidative stress in PC12 cells, and exerted influence on lipid metabolism in DB/DB mice.

G-CSF and cognitive dysfunction in elderly diabetic mice with cerebral small vessel disease: Preventive intervention effects and underlying mechanisms.

AIMS: Although cognitive dysfunction is a common neurological complication in elderly patients with diabetes, the mechanisms underlying this relationship remain unclear, and effective preventive interventions have yet to be developed. Thus, this study investigated the preventive effects and mechanisms of action associated with granulocyte colony-stimulating factor (G-CSF) on cognitive dysfunction in elderly diabetic mice with cerebral small vessel disease. METHODS: This study included 40 male db/db diabetic and wild-type (WT) mice that were categorized into the following four groups at the age of 3 weeks: db/db group (DG), db/db+G-CSF group (DGG), WT group (WG), and WT+G-CSF group (WGG). The mice were fed normal diets for 4 months and then given G-CSF (75 µg/kg) via intraperitoneal injections for 1 month. At 7.5 months of age, the cognitive abilities of the mice were assessed with the Y-maze test and the Social Choice Test; body weight, blood pressure (BP), and blood glucose measurements were obtained throughout the study. Brain imaging and blood oxygen level-dependent (BOLD) contrast imaging analyses were performed with a small animal magnetic resonance imaging (MRI) system, autophagosome levels were detected with a transmission electron microscope (TEM), hippocampal neurons were assessed with hematoxylin and eosin (HE) staining, and protein expressions and distributions were evaluated using immunohistochemistry and Western blot analyses. RESULTS: (i) The body weight and blood glucose levels of the DG and DGG mice were significantly higher than those of the WG and WGG mice; (ii) social choice and spatial memory capabilities were significantly reduced in DG mice but were recovered by G-CSF in DGG mice; (iii) the MRI scans revealed multiple lacunar lesions and apparent hippocampal atrophy in the brains of DG mice, but G-CSF reduced the number of lacunar lesions and ameliorated hippocampal atrophy; (iv) the MRI-BOLD scans showed a downward trend in whole-brain activity and reductions in the connectivities of the hippocampus and amygdala with subcortical structures in DG mice, but G-CSF clearly improved the altered brain activity as well as the connectivity of the hippocampus in DGG mice; (v) HE staining revealed fewer neurons in the hippocampus in DG mice; (vi) TEM analyses revealed significantly fewer autophagosomes in the hippocampi of DG mice, but G-CSF did not increase these numbers; (vii) there were significant reductions in mechanistic target of rapamycin (mTOR) and LC3-phosphatidylethanolamine conjugate (LC3)-II/I levels in the hippocampi of DG mice, whereas p62 was upregulated, and G-CSF significantly enhanced the levels of Beclin1, mTOR, and LC-II/I in DGG mice; and (viii) G-CSF significantly reversed increases in nuclear factor κB (NF-κB) protein levels in DG but not in WG mice. CONCLUSIONS: In this study, aged diabetic mice were prone to cognitive dysfunction and cerebral small vessel disease. However, administration of G-CSF significantly improved cognitive function in elderly db/db diabetic mice, and this change was likely related to the regulation of autophagy and NF-κB signaling pathways.

Glutathione prevents free fatty acids-induced oxidative stress and apoptosis in human brain vascular endothelial cells through Akt pathway.

AIMS: The damage of human brain vascular endothelial cells (HBVECs) is the key pathogenesis of diabetes-associated cerebral vascular complications. The aim of this study was to elucidate the effects of glutathione (GSH) on free fatty acids (FFAs)-induced HBVECs apoptosis, oxidative stress, and the involved possible signaling pathway. METHODS: After culturing HBVECs for 72 h with GSH and FFAs, we determined cell proliferation by CCK8, detected apoptosis by caspase-3 and Annexin V-FITC/PI staining, and judged oxygen stress by determining the reactive oxygen species (ROS) and the mitochondrial membrane potential (MMP). We investigated whether the Akt pathway was involved in FFAs-induced signaling pathway alteration and whether GSH influenced the above effects. RESULTS: After being cultured in 200 µM FFAs for 72 h, the HBVECs proliferation significantly decreased; HBVECs apoptosis increased; the ROS levels increased; and the HBVECs MMP subsequently decreased. FFAs induced a significant decrease in phosphorylated active Akt. These alterations were obviously prevented when 1 mM GSH was added to culture medium containing FFAs, and the above effects of GSH were blocked by Akt inhibitor. CONCLUSION: GSH may prevent FFAs-induced HBVECs damage, oxidative stress, and apoptosis through activating the Akt pathway.

Effects of epithelial cell injury of the lower respiratory tract in the pathogenesis of allergic responses in a rat model.

BACKGROUND: Asthma is a complex disease involving genetic and environment interactions. Atopy is a strong risk factor for asthma. The airway epithelium not only forms a physical barrier but also provides immune defense against harmful materials. To explore the effects of airway epithelium on asthma, we hypothesized that environmental injuries could act on bronchial epithelial cells and damage the physical barrier, which might facilitate allergens to stimulate immunoreactions and play an important role in the pathogenesis of asthma. METHODS: Thirty eight-week-old male Wistar rats were randomly divided into five groups with six rats in each group: control group, asthma group, ovalbumin (OVA) + OVA group, lipopolysaccharide (LPS) group and LPS + OVA group. In the control group, 0.9% saline was injected intraperitoneally on day 1. Fourteen days later, the rats were exposed to aerosolized 0.9% saline. In the asthma group, the rats were sensitized with an injection of 10 mg of OVA, followed by an aerosolized 2% OVA challenge 14 days later. The OVA + OVA group was sensitized by an inhalation 2% OVA, 20 minutes a day, from day 1 to day 7, and then OVA challenged in the same way as the asthma group. In the LPS group, LPS (200 µl, 1 µg/µl) was given by airway on day 1 and day 3, with a simultaneous aerosol inhalation of 2% OVA for 20 minutes a day from day 1 to day 7. Fourteen days later, the rats were challenged with saline as in the control group. While in the LPS + OVA group, LPS (200 µl, 1 µg/µl) was given by airway on day 1 and day 3, with a simultaneous aerosol inhalation of 2% OVA for 20 minutes a day from day 1 to day 7. Fourteen days later, the rats were challenged with OVA as in the asthma group. The expression of interleukin (IL)-4, interferon-gamma (IFN-γ) and thymic stromal lymphopoietin (TSLP) in the lungs was detected by reverse transcription polymerase chain reaction (RT-PCR) and the pulmonary pathological changes were also observed. The level of IL-4, IFN-γ and IgE in plasma was detected by enzyme-linked immunosorbent assay (ELISA). Bronchoalveolar lavage fluid (BALF) was collected to conduct differential cell counts. Flow cytometry analysis was also used to count Th1 and Th2 cells. RESULTS: The pathological changes in the LPS + OVA group were similar to the asthma group, while in other groups, the pathological changes were not obvious. The ratio of lymphocytes in BALF, IL-4/IFN-γ in plasma and the expression of the TSLP and IL-4 in the asthma and LPS + OVA groups were higher than in the control group and the OVA + OVA group (P < 0.05). The level of IgE was higher in the asthma, LPS and LPS + OVA groups than in the control group and the OVA + OVA group (P < 0.05). By flow cytometry analysis, the Th1/Th2 ratio was lower in the LPS + OVA and asthma groups than in other groups (P < 0.05). CONCLUSIONS: The experiment results show that the injury to the bronchial epithelial layer may be the initial event of allergic responses. This finding implies that a rational approach to therapeutics would be to increase the resistance of the airways to environmental injuries rather than concentrating on suppressing inflammation.