Effect of limb ischemic preconditioning on myocardial apoptosis-related proteins in ischemia-reperfusion injury

Tao-Hong-Si-Wu decoction reduces ischemia reperfusion rat myoblast cells calcium overloading and inflammation through the Wnt/IP3R/CAMKII pathway

Limb ischemia reperfusion (LIRI) injury is associated with serious local and systemic effects. Reperfusion may augment tissue injury in excess of that produced by ischemia alone. Calcium overloading and inflammation are considered to be two of the pathological mechanisms of limb ischemia/reperfusion (I/R) injury. Tao-Hong-Si-Wu decoction (THSWD) is a traditional Chinese herbal medicine with a powerful anti-inflammatory properties. We studied the probable restorative effect of THSWD on limb I/R-induced calcium overloading and inflammation in myoblast obtained from gastrocnemius muscle tissues of Sprague-Dawley rats (Frizzled Z5,a wnt5a blocker; KN-93, a calmodulin-dependent protein kinase II (CamkII) blocker; XeC, a IP3R blocker as positive controls). The simulated ischemia and reperfusion(I/R) solutions were used to imitate LIRI environment. The results showed that after I/R treatment, the secretion of proinflammatory factors (TNF-α and IL-1β) and Wnt5a/Ca²⁺ signal molecules (wnt5a, camkII, and IP3R) upregulated significantly, the Ca²⁺ concentration enhanced too in myoblast cells. THSWD pretreatment decreased the secretion of TNF-α and IL-1β, Ca²⁺ concentration; and abated the Wnt5a/Ca²⁺ signal molecules of wnt5a, camkII and IP3R expression activated by I/R injury; but could not abated the Wnt11 and protein kinase C (PKC) expression significantly, the results was similar with Frizzled Z5 treatment cells. Our research illustrated that THSWD may have a mitigating effect on LIRI targeting Wnt/IP3R/CAMKII but not Wnt/IP3R/PKC signaling pathway for the first time. This study may encourage the use of THSWD in the critical clinical settings with LIRI.

Iodine-131 induces apoptosis in human cardiac muscle cells through the p53/Bax/caspase-3 and PIDD/caspase-2/ t‑BID/cytochrome c/caspase-3 signaling pathway

The aim of this study was to elucidate the effects of iodine-131 on the induction of apoptosis in human cardiac muscle cells and the underlying molecular mechanisms. We found that iodine-131 reduced cell proliferation, induced apoptosis, induced p53, PIDD, t-BID (mitochondria) protein expression, suppressed cytochrome c (mitochondria) protein expression, and increased Bax protein expression, and promoted caspase-2, -3 and -9 expression levels in human cardiac muscle cells. Meanwhile, si-p53 inhibited the effects of iodine-131 on the reduction in cell proliferation and induction of apoptosis in human cardiac muscle cells through regulation of Bax/cytochrome c/caspase-3 and PIDD/caspase‑2/t-BID/cytochrome c/caspase-3 signaling pathway. After si-Bax reduced the effects of iodine-131, it reduced cell proliferation and induced apoptosis in human cardiac muscle cells through the cytochrome c/caspase-3 signaling pathway. However, si-caspase-2 also reduced the effects of iodine-131 on the reduction of cell proliferation and induction of apoptosis in human cardiac muscle cells through the t-BID/cytochrome c/caspase-3 signaling pathway. These findings demonstrated that iodine-131 induces apoptosis in human cardiac muscle cells through the p53/Bax/caspase-3 and PIDD/caspase-2/t-BID/cytochrome c/caspase-3 signaling pathway.

Augmented O-GlcNAc signaling via glucosamine attenuates oxidative stress and apoptosis following contrast-induced acute kidney injury in rats

Contrast-induced acute kidney injury (CI-AKI) is an iatrogenic renal injury and associated with substantial morbidity and mortality in susceptible individuals. Despite extensive study of a variety of agents for renal protection, limited strategies have been shown to be effective in the reduction of CI-AKI. O-linked β-N-acetylglucosamine (O-GlcNAc) is a post-translational regulatory modification of intracellular proteins and governs the function of numerous proteins, both cytosolic and nuclear. Increasing evidence suggests that O-GlcNAc levels are increased in response to stress and that acute augmentation of this reaction is cytoprotective. However, the underlying mechanisms by which augmented OGlcNAc signaling provides renoprotection against contrast media insults is still unknown. Here, we investigated the effect of augmented O-GlcNAc signaling via glucosamine on CI-AKI and explored the underlying molecular mechanisms, particularly its relationship with PI3-kinase (PI3K)/Akt signaling. We used a novel and reliable CI-AKI model consisting of 5/6 nephrectomized (NE) rats, and a low-osmolar contrast media (iohexol, 10mL/kg, 3.5gI) injected via the tail vein after dehydration for 48h. The results showed that augmented O-GlcNAc signaling by glucosamine prevented the kidneys against iohexol-induced injury characterized by the attenuation of renal dysfunction, tubular damage, apoptosis and oxidative stress. Furthermore, this renoprotection was blocked by treatment with alloxan, an O-GlcNAc transferase inhibitor. Augmented O-GlcNAc signaling also increased the protein expression levels of phospho-Akt (Ser473, but not Thr308 and Thr450), phospho-GSK-3β, Nrf2, and Bcl-2, and decreased the levels of Bax and cleaved caspase-3. Both alloxan and specific inhibitors of PI3K (Wortmannin and LY294002) blocked the protection of glucosamine via inhibiting Akt signaling pathway. We further identified O-GlcNAcylated Akt through immunoprecipitation and western blot. We confirmed that Akt was modified by O-GlcNAcylation, and glucosamine pretreatment increased the O-GlcNAcylation of Akt. Collectively, the results demonstrate that glucosamine induces renoprotection against CI-AKI through augmented O-GlcNAc and activation of PI3K/Akt signaling, making it a promising strategy for preventing CI-AKI.

DIFFERENT PROTOCOLS OF POSTCONDITIONING DOES NOT ATTENUATE MESENTERIC ISCHEMIA-REPERFUSION INJURY AFTER SHORT-TERM REPERFUSION

Background

Mesenteric ischemia is a challenging diagnosis. Delay in diagnosis can lead to extent bowel necrosis and poor outcomes. Ischemia and reperfusion syndrome plays an important role in this scenario.

Aim

To access effects of different post-conditioning cycles on mesenteric ischemia-reperfusion syndrome.

Method

Twenty-five rats were assigned into five groups: Sham, used to establish normal parameters; control group, submitted to mesenteric ischemia for 30 min; in groups GP3, GP1 and GP30, ischemia was followed by post-conditioning protocol, which consisted of 1 cycle of 3 min (GP3), 3 cycles of 1 min (GP1) or 6 cycles of 30 s (GP30), respectively. Ileum samples were harvested after one hour of reperfusion. Intestinal mucosal injury was evaluated through histopathological analysis.

Results

The average of mesenteric injury degree was 0 in the sham group, 3.6 in the control group, 3.4 in GP3, 3.2 in GP1, and 3.0 in GP30; villous length average was 161.59 in sham group, 136.27 in control group, 135.89 in GP3, 129.46 in GP1, and 135.18 in GP30. Was found significant difference between sham and other groups (p<0.05); however, there was no difference among post-conditioning groups.

Conclusion

Post-conditioning adopted protocols were not able to protect intestinal mucosa integrity after mesenteric ischemia and short term reperfusion.

Regulatory effect of Bcl-2 in ultraviolet radiation-induced apoptosis of the mouse crystalline lens

The aim of the present study was to analyze the role of Bcl-2 during the process of apoptosis in the mouse crystalline lens. In total, 12 normal mice served as the control group and 12 Bcl-2 knockout (K.O) mice served as the experimental group. The mouse crystalline lens was sampled for the detection of Bcl-2 and caspase-3 expression following exposure to ultraviolet (UV) radiation. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to determine Bcl-2 expression in the groups of normal mice receiving UV radiation or not receiving UV radiation. Samples of the murine crystalline lens were microscopically harvested and analyzed using western blotting. Apoptosis was detected using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Furthermore, caspase 3 activity was examined using enzyme-linked immunosorbent assay kits, and RT-qPCR was used to analyze caspase-3 expression levels. The results of the present study demonstrated that there was no statistically significant difference in the level of Bcl-2 gene transcription between the two groups. In addition, UV radiation did not change the macrostructure of the crystalline lens in the group of normal mice or the group of Bcl-2 K.O mice. The results of the TUNEL assay indicated that the normal-UV group exhibited a more significant apoptosis level compared with the Bcl-2 K.O-UV group. Furthermore, the mRNA expression level of caspase-3 in the normal-UV group was significantly higher compared with the normal-nonUV group (P<0.05), while the levels in the Bcl-2 K.O-UV group were significantly higher compared with the Bcl-2 K.O and normal-nonUV groups (P<0.05). In addition, the mRNA expression level of caspase-3 was significantly higher in the normal-UV, as compared with the Bcl-2 K.O-UV group (P<0.05), and the variation trends in caspase-3 activity were consistent. In conclusion, the results of the present study demonstrated that Bcl-2 may have an important role in the promotion of UV-induced apoptosis in the crystalline lens.

Limb ischemic preconditioning protects against contrast-induced acute kidney injury in rats via phosphorylation of GSK-3β

Contrast-induced acute kidney injury (CI-AKI) resulting from the use of intravascular iodinated contrast media for diagnostic and interventional cardiovascular procedures is associated with substantial morbidity and mortality. Despite preventative measures intended to mitigate the risk of CI-AKI, there remains a need for a novel and effective therapeutic approach. Limb ischemic preconditioning (LIPC), where short-term ischemia/reperfusion is applied to an arm prior to administration of the contrast agent, has been shown in several trials to preserve renal function in patients at high risk for CI-AKI. However, the underlying mechanism by which this procedure provides renoprotection against contrast media insults is not known. Here, we explored the molecular mechanism(s) of LIPC-induced protection of the kidneys from CI-AKI, particularly the role of phosphorylated glycogen synthase kinase-3β (GSK-3β). We used a novel CI-AKI model consisting of 5/6 nephrectomized (NE) rats at 6 weeks after the ablative surgery. LIPC- or sham-treated rats were administered iohexol (10 ml/kg, 3.5 gI) via the tail vein. The results showed that LIPC protected the kidneys against iohexol-induced injury. This protective effect was accompanied by the attenuation of renal dysfunction, tubular damage, apoptosis, mitochondrial swelling, oxidative stress, and inflammation. Furthermore, LIPC-induced renoprotection was blocked via treatment with inhibitors of PI3K (wortmannin or LY294002), but not ERK (U0126 or PD98059). LIPC also increased the protein expression levels of phospho-Akt, phospho-GSK-3β, and nuclear Nrf2, and decreased the levels of nuclear NF-κB. A specific GSK-3β inhibitor (SB216763) mimicked this effect of LIPC, by inhibiting the opening of the mitochondrial permeability transition pore and reducing the levels of oxidative stress and inflammation via activation of Nrf2 and suppression of NF-κB. The above results demonstrate that LIPC induces protection against CI-AKI, making this procedure a promising strategy for preventing CI-AKI. In particular, this renoprotective effect involves the phosphorylation of GSK-3β.

Resuscitation after cardiac arrest in a septic porcine model: adding vasopressin vs epinephrine alone administration

Background

Vasopressin administration has been tested in cardiac arrest. However it has not been tested when cardiac arrest occurs in certain circumstances, as in sepsis, where it may have a major role. The aim of the study was to investigate survival after cardiac arrest in a septic porcine model compared with healthy animals and to explore the effectiveness of adding vasopressin vs epinephrine alone administration.

Methods

Thirty five healthy piglets of both genders were studied. The piglets were randomly assigned into three groups: group A (n = 8), group B (n = 14), group C (n = 13). Animals of groups B and C were given endotoxin to mimic a septic state before arrest. We applied the same resuscitation protocol to all pigs but we replaced the first dose of epinephrine with vasopressin in pigs of group C. Following surgical preparation and 30 min resting period, baseline measurements were recorded. In order to assess tissue oxygenation, we implemented Near Infrared Spectroscopy (NIRS) with the vascular occlusion technique (VOT) in thirteen lipopolysaccharide (LPS)-treated animals, occluding abdominal aorta and inferior vena cava. Afterwards, LPS (100 μg/kg) was infused in a 30 min period to animals of groups B and C and normal saline to group A. New NIRS measurements were obtained again. Subsequently, we provoked ventricular fibrillation (VF). After 3 min of untreated VF, open chest cardiopulmonary resuscitation (CPR) was performed manually. Primary end point was the restoration of spontaneous circulation (ROSC).

Results

The chance of ROSC for the groups A, B and C was 75%, 35.7%, and 30.7% respectively. A significant difference in ROSC was established between septic (group B + C) and non septic piglets (group A) (P = 0.046). Vasopressin administration had no effect in outcome. LPS administration decreased oxygen consumption rate, as assessed by NIRS, in peripheral tissues (22.6 ± 7.2. vs 18.5 ± 7.2, P = 0.07).

Conclusion

Septic piglets have fewer chances to survive after cardiac arrest. No difference in outcome was observed when the first dose of epinephrine was replaced with vasopressin to treat cardiac arrest in the LPS-treated animals.