Lower limb ischaemia-reperfusion injury alters gastrointestinal structure and function

Effect of microRNA-26a on vascular endothelial cell injury caused by lower extremity ischemia-reperfusion injury through the AMPK pathway by targeting PFKFB3

Vascular endothelial cell (VEC) dysfunction plays an important role in the ischemia-reperfusion injury (IRI)-related diseases, and microRNAs (miRNAs) are key factors during this process. We conducted this study to investigate whether miRNA-26a (miR-26a) has effect on the IRI-induced VEC injury via the AMPK pathway by targeting 6-phosphofructo-2-kinase-fructose-2,6-biphosphatase 3 (PFKFB3). IRI rat models were successfully constructed by an abdominal incision. Additionally, the cultured VECs were further treated with miR-26a mimic or inhibitor, and si-PFKFB3. Both the reverse-transcription quantitative polymerase chain reaction and the western blot assay method were carried out to examine the expressions of PFKFB3, endothelial nitric oxide synthase (eNOS), and 5'-adenosine monophosphate-activated protein kinase (AMPK) α1, as well as the extent of the AMPK α1 phosphorylation levels in vascular tissues. Circulating endothelial cell (CEC), von Willebrand factor (VWF), thrombomodulin (TM), superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), and endothelin (ET) were all measured. In the rat model of an IRI, a poorly expressed miR-26a and contrarily highly expressed PFKFB3 were identified in vascular tissues. In response to an overexpression of miR-26a or to the PFKFB3 gene silencing, decreased CEC number, TM, VWF, MDA, and ET contents, increased AMPK α1, and eNOS levels, as well as the extent of AMPK α1 phosphorylation coordinate with both increased SOD and NO contents based on the restoration of the AMPK pathway. Overexpression of the miR-26a or si-PFKFB3 provides an elevation in cell proliferation. Our study suggests that the miR-26a RNA alleviates lower extremity IRI-induced VEC injury in rats through the activation of the AMPK pathway by inhibiting PFKFB3.

Anti-oxidative stress effect of proanthocyanidin on intestinal mucosa of rats with limb ischemia-reperfusion injury

AIM: To investigate the protective effect of proanthocyanidin (PC) on the intestinal mucosa of rats with limb ischemia-reperfusion (LI/R) and to explore the possible mechanism.

METHODS: Twenty-one male adult Sprague-Dawley rats were randomly divided into three groups (n = 7): sham operation group, LI/R group and PC group. The PC group received 100 mg/(kg•d) PC via oral gavage for 7 d before LI/R. The sham operation and LI/R groups were given the same dose of salad oil each day for 7 d. A tourniquet was used to tie the rat left hind limb to induce LI/R injury in rats (ischemia 3 h and reperfusion 18 h). Following reperfusion, the abdominal cavity was opened and blood samples were taken from the abdominal aorta to determine serum superoxide dismutase (SOD) and malondialdehyde (MDA) levels. Segments of the ileum were quickly resected and equally separated into two parts to conduct hematoxylin & eosin (H&E) staining and determine tissue secretory immunoglobulin A (sIgA) levels, respectively.

RESULTS: Compared with the sham operation group, serum SOD activity was significantly decreased (P < 0.01), MDA levels were significantly increased (P < 0.01), mucosal injury was significantly aggravated in light microscopic evaluations (P < 0.01) and tissue sIgA (P < 0.01) was significantly reduced after LI/R. Compared with the LI/R group, pretreatment with PC significantly enhanced serum SOD activity (P < 0.05), decreased MDA levels (P < 0.01), mitigated intestinal mucosal injury (P < 0.01) and increased the tissue sIgA contents (P < 0.05).

CONCLUSION: PC protects the intestinal mucosa by elevating serum SOD activity, reducing MDA levels and increasing tissue sIgA contents in rats after LI/R injury.

Remote ischemic postconditioning protects against gastric mucosal lesions in rats

AIM: To investigate the protective effects of remote ischemic postconditioning (RIP) against limb ischemia-reperfusion (IR)-induced gastric mucosal injury.

METHODS: Gastric IR was established in male Wistar rats by placing an elastic rubber band under a pressure of 290-310 mmHg on the proximal part of both lower limbs for 3 h followed by reperfusion for 0, 1, 3, 6, 12 or 24 h. RIP was performed using three cycles of 30 s of reperfusion and 30 s of reocclusion of the femoral aortic immediately after IR and before reperfusion for up to 24 h. Rats were randomly assigned to receive IR (n = 36), IR followed by RIP (n = 36), or sham treatment (n = 36). Gastric tissue samples were collected from six animals in each group at each timepoint and processed to determine levels of malondialdehyde (MDA), superoxide dismutase (SOD), xanthine oxidase (XOD) and myeloperoxidase (MPO). Additional samples were processed for histologic analysis by hematoxylin and eosin staining. Blood samples were similarly collected to determine serum levels of lactate dehydrogenase (LDH), creatine kinase (CK), tumor necrosis factor (TNF)-α and interleukin (IL)-10.

RESULTS: The pathologic changes in gastric tissue induced by IR were observed by light microscopy. Administration of RIP dramatically reduced the gastric damage score after 6 h of reperfusion (5.85 ± 0.22 vs 7.72 ± 0.43; P < 0.01). In addition, RIP treatment decreased the serum activities of LDH (3.31 ± 0.32 vs 6.46 ± 0.03; P < 0.01), CK (1.94 ± 0.20 vs 4.54 ± 0.19; P < 0.01) and the concentration of TNF-α (53.82 ± 0.85 vs 88.50 ± 3.08; P < 0.01), and elevated the concentration of IL-10 (101.46 ± 5.08 vs 99.77 ± 4.32; P < 0.01) induced by IR at 6 h. Furthermore, RIP treatment prevented the marked elevation in MDA (3.79 ± 0.29 vs 6.39 ± 0.81) content, XOD (7.81 ± 0.75 vs 10.37 ± 2.47) and MPO (0.47 ± 0.05 vs 0.82 ± 0.03) activities, and decrease in SOD (4.95 ± 0.32 vs 3.41 ± 0.38; P < 0.01) activity in the gastric tissue as measured at 6 h.

CONCLUSION: RIP provides effective functional protection and prevents cell injury to gastric tissue induced by limb IR via anti-inflammatory and antioxidant actions.