G[alpha]i2 and G[alpha]q expression change in pancreatic tissues and BN52021 effects in rats with severe acute pancreatitis

Ginkgolide B ameliorates myocardial ischemia reperfusion injury in rats via inhibiting endoplasmic reticulum stress

Purpose

Ginkgolide B (GB) is a terpene lactone component found in Ginkgo biloba, which has a protective role on ischemia reperfusion (I/R) injury. This study was aimed at exploring the protective mechanism of GB on the myocardial I/R.

Patients and methods

Myocardial I/R model was established on Sprague Dawley rats. The levels of cardiac troponin I, cardiac troponin T, lactic dehydrogenase, and myoglobin were determined by a 200FR NEO automatic biochemical analyzer. Histological examination was performed through HE and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining. The expression levels of p-PERK, p-IRE1α, ATF6, p-AKT, and mTOR were detected by Western blot.

Results

The results exhibited that GB treatment suppressed the high levels of cardiac troponin I, cardiac troponin T, lactic dehydrogenase, and myoglobin and ameliorated the damaged and irregularly arranged myocardial cells induced by I/R injury significantly, indicating that GB could ameliorate myocardial I/R injury. Moreover, the high expression levels of endoplasmic reticulum (ER) stress key proteins caused by I/R injury were suppressed significantly by GB treatment, including p-PERK, p-IRE1α, and ATF6. GB treatment also decreased the number of apoptotic cells compared with I/R group. In addition, activation of ER stress by Tunicamycin treatment could counteract the protective effects of GB on I/R injury, suggesting that GB ameliorated myocardial I/R injury through inhibition of ER stress-induced apoptosis. Finally, the decreased p-AKT and p-mTOR expressions caused by I/R injury were upregulated by GB and inhibition of PI3K/AKT/mTOR pathway by LY294002 abolished the protective effects of GB on I/R injury, indicating that GB activated PI3K/AKT/mTOR pathway during I/R injury.

Conclusion

GB protected against myocardial I/R injury through inhibiting ER stress-induced apoptosis via PI3K/AKT/mTOR signaling pathway.

Deficiency of the G protein Gαq ameliorates experimental autoimmune encephalomyelitis with impaired DC-derived IL-6 production and Th17 differentiation

Many G protein-coupled receptors (GPCRs) are reported to be involved in the pathogenesis of multiple sclerosis (MS), and ~40% of all identified GPCRs rely on the Gαq/11 G protein family to stimulate inositol lipid signaling. However, the function of Gα subunits in MS pathogenesis is still unknown. In this study, we attempted to determine the role of Gαq in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a well-known mouse model of MS. We discovered that compared with wild-type mice, Gαq-knockout mice exhibited less severe EAE symptoms, with lower clinical scores, reduced leukocyte infiltration and less extensive demyelination. Moreover, a significantly lower percentage of Th17 cells, one of the key players in MS pathogenesis, was observed in Gαq-knockout EAE mice. Studies in vitro demonstrated that deficiency of Gαq in CD4⁺ T cells directly impaired Th17 differentiation. In addition, deficiency of Gαq significantly impaired DC-derived IL-6 production, thus inhibiting Th17 differentiation and the Gαq-PLCβ-PKC and Gαq-MAPKs signaling pathways involved in the reduced IL-6 production by DCs. In summary, our data highlighted the critical role of Gαq in regulating Th17 differentiation and MS pathogenesis.

Ginkgolide B Exerts Cardioprotective Properties against Doxorubicin-Induced Cardiotoxicity by Regulating Reactive Oxygen Species, Akt and Calcium Signaling Pathways In Vitro and In Vivo

The aim of this study was to evaluate the effect of Ginkgolide B (GB) on doxorubicin (DOX) induced cardiotoxicity in vitro and in vivo. Rat cardiomyocyte cell line H9c2 was pretreated with GB and subsequently subjected to doxorubicin treatment. Cell viability and cell apoptosis were assessed by MTT assay and Hoechst staining, respectively. Reactive oxygen species (ROS), Akt phosphorylation and intracellular calcium were equally determined in order to explore the underlying molecular mechanism. To verify the in vivo therapeutic effect of GB, we established a mouse model of cardiotoxicity and determined left ventricle ejection fraction (LVEF) and left ventricular mass (LVM). The in vitro experimental results indicated that pretreatment with GB significantly decreases the viability and apoptosis of H9c2 cells by decreasing ROS and intracellular calcium levels and activating Akt phosphorylation. In the in vivo study, we recorded an improved LVEF and a decreased LVM in the group of cardiotoxic rats treated with GB. Altogether, our findings anticipate that GB exerts a cardioprotective effect through possible regulation of the ROS, Akt and calcium pathways. The findings suggest that combination of GB with DOX in chemotherapy could help avoid the cardiotoxic side effects of GB.

Roles of BN52021 in platelet-activating factor pathway in inflammatory MS1 cells

AIM: To determine the effects of BN52021 on platelet-activating factor receptor (PAFR) signaling molecules under lipopolysaccharide (LPS)-induced inflammatory conditions in MS1 cells.

METHODS: MS1 cells (a mouse pancreatic islet endothelial cell line) were grown in Dulbecco’s modified Eagle’s medium supplemented with 10% fetal bovine serum, 2 mmol/L glutamine and 100 μg/mL penicillin/streptomycin in 5% CO₂ at 37 °C. After growth to confluency in media, the cells were processed for subsequent studies. The MS1 cells received 0, 0.1, 1 and 10 μg/mL LPS in this experiment. The viability/proliferation of the cells induced by LPS was observed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay. Apoptosis and necrosis of the cells under the inflammatory condition described previously were observed using Hoechst 33342-propidium iodide staining. Adenylate cyclase (AC), phospholipase A₂ (PLA₂), phospholipase Cβ (PLCβ), protein tyrosine kinase (PTK), G protein-coupled receptor kinases (GRK) and p38-mitogen-activated protein kinase (p38 MAPK) mRNA in the PAFR signaling pathway were measured by real-time polymerase chain reaction. The protein expression level of phosphorylated AC (p-AC), phosphorylated PLA₂ (p-PLA₂), phosphorylated PTK (p-PTK), phosphorylated p38 MAPK (p-p38 MAPK), PLCβ and GRK was measured using Western blotting analysis.

RESULTS: The activity of MS1 cells incubated with different concentrations of LPS for 6 h decreased significantly in the 1 μg/mL LPS group (0.49 ± 0.10 vs 0.67 ± 0.13, P < 0.05) and 10 μg/mL LPS group (0.44 ± 0.10 vs 0.67 ± 0.13, P < 0.001), but not in 0.1 μg/mL group. When the incubation time was extended to 12 h (0.33 ± 0.05, 0.32 ± 0.03 and 0.25 ± 0.03 vs 0.69 ± 0.01) and 24 h (0.31 ± 0.01, 0.29 ± 0.03 and 0.25 ± 0.01 vs 0.63 ± 0.01), MS1 cell activity decreased in all LPS concentration groups compared with the blank control (P < 0.001). BN52021 significantly improved the cell activity when its concentration reached 50 μmol/L compared with the group that received LPS treatment alone, which was consistent with the results obtained from fluorescence staining. The mRNAs levels of AC (4.02 ± 0.14 vs 1.00 ± 0.13), GRK (2.63 ± 0.03 vs 1.00 ± 0.12), p38 MAPK (3.87 ± 0.07 vs 1.00 ± 0.17), PLA₂ (3.31 ± 0.12 vs 1.00 ± 0.12), PLCβ (2.09 ± 0.08 vs 1.00 ± 0.06) and PTK (1.85 ± 0.07 vs 1.00 ± 0.11) were up-regulated after LPS stimulation as compared with the blank control (P < 0.05). The up-regulated mRNAs including AC (2.35 ± 0.13 vs 3.87 ± 0.08), GRK (1.17 ± 0.14 vs 2.65 ± 0.12), p38 MAPK (1.48 ± 0.18 vs 4.30 ± 0.07), PLCβ (1.69 ± 0.10 vs 2.41 ± 0.13) and PLA₂ (1.87 ± 0.11 vs 2.96 ± 0.08) were significantly suppressed by BN52021 except for that of PTK. The level of p-AC (1.11 ± 0.12 vs 0.65 ± 0.08), GRK (0.83 ± 0.07 vs 0.50 ± 0.03), PLCβ (0.83 ± 0.16 vs 0.50 ± 0.10) and p-p38 MAPK (0.74 ± 0.10 vs 0.38 ± 0.05) was up-regulated after LPS stimulation as compared with the blank control (P < 0.05). The up-regulated proteins, including p-AC (0.65 ± 0.15 vs 1.06 ± 0.14), GRK (0.47 ± 0.10 vs 0.80 ± 0.06), PLCβ (0.47 ± 0.04 vs 0.80 ± 0.19) and p-p38 MAPK (0.30 ± 0.10 vs 0.97 ± 0.05), was significantly suppressed by BN52021, but p-PLA₂ and p-PTK protein level were not suppressed.

CONCLUSION: BN52021 could effectively inhibit LPS-induced inflammation by down-regulating the mRNA and protein levels of AC, GRK, p38 MAPK, PLA₂ and PLCβ in the PAFR signaling pathway.

Immune dysregulation in patients with severe acute pancreatitis

To investigate patients with severe acute pancreatitis (SAP) by dynamic levels of pro-/anti-inflammatory cytokines and endotoxin (ET) in plasma and the relationship between immunity and infection, organ dysfunction. Seventy-two patients with SAP were recruited. The ET, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-4 (IL-4) were determined on admission and days 3, 7, and 14. For comparison, patients were analyzed through infection group versus non-infection group, multiple organ dysfunction syndrome (MODS) group versus non-MODS group. There were sixteen patients with secondary infection, twenty-two with MODS, and nine deaths. The infection group had higher levels of ET than the non-infection group on days 3 and 7. The dynamic cytokine levels of patients in the MODS group were unanimous with those outcomes in the infection group. The levels of cytokines in the infection group were different from the non-infection group, with more levels of TNF-α, IL-6 on days 3 and 7 and less on days 14, and more levels of IL-10, IL-4 on days 7 and 14. The levels of TNF-α, IL-6 in the MODS group were different from the non-MODS group, with more levels on days 3 and 7, and less levels on days 14. Immune dysregulation may play an important role in infection and organ dysfunction for patients with SAP.