Ischemic postconditioning ameliorates acute kidney injury induced by limb ischemia/reperfusion via transforming TLR4 and NF-κB signaling in rats

Tourniquet-induced ischemia creates increased risk of organ dysfunction and mortality following delayed limb amputation

Tourniquets are critical for the control of traumatic extremity hemorrhage. In this study, we sought to determine, in a rodent blast-related extremity amputation model, the impact of prolonged tourniquet application and delayed limb amputation on survival, systemic inflammation, and remote end organ injury. Adult male Sprague Dawley rats were subjected to blast overpressure (120±7 kPa) and orthopedic extremity injury consisting femur fracture, one-minute soft tissue crush injury (20 psi), ± 180 min of tourniquet-induced hindlimb ischemia followed by delayed (60 min of reperfusion) hindlimb amputation (dHLA). All animals in the non-tourniquet group survived whereas 7/21 (33%) of the animals in the tourniquet group died within the first 72 h with no deaths observed between 72 and 168 h post-injury. Tourniquet induced ischemia-reperfusion injury (tIRI) likewise resulted in a more robust systemic inflammation (cytokines and chemokines) and concomitant remote pulmonary, renal, and hepatic dysfunction (BUN, CR, ALT. AST, IRI/inflammation-mediated genes). These results indicate prolonged tourniquet application and dHLA increases risk of complications from tIRI, leading to greater risk of local and systemic complications including organ dysfunction or death. We thus need enhanced strategies to mitigate the systemic effects of tIRI, particularly in the military prolonged field care (PFC) setting. Furthermore, future work is needed to extend the window within which tourniquet deflation to assess limb viability remains feasible, as well as new, limb-specific or systemic point of care tests to better assess the risks of tourniquet deflation with limb preservation in order to optimize patient care and save both limb and life.

Effect of dexmedetomidine on tourniquet-induced skeletal muscle injury

OBJECTIVE

The aim of this study was to investigate whether dexmedetomidine could reduce tourniquet-induced skeletal muscle injury.

METHODS

C57BL6 male mice were randomly assigned to sham, ischemia/reperfusion, and dexmedetomidine groups. Mice in the ischemia/reperfusion and dexmedetomidine groups received normal saline solution and dexmedetomidine intraperitoneally, respectively. The sham group underwent the same procedure as the ischemia/reperfusion group, with the exception of tourniquet application. Subsequently, the ultrastructure of the gastrocnemius muscle was observed, and its contractile force was examined. In addition, Toll-like receptor 4 and nuclear factor-κB expression within muscles was detected by Western blot.

RESULTS

Dexmedetomidine alleviated myocyte damage and increased the contractility of skeletal muscles. Moreover, dexmedetomidine significantly inhibited the expression of Toll-like receptor 4/nuclear factor-κB in the gastrocnemius muscle.

CONCLUSION

Taken together, these results demonstrate that dexmedetomidine administration attenuated tourniquet-induced structural and functional impairment of the skeletal muscle, partly through inactivation of the Toll-like receptor 4/nuclear factor-κB pathway.

Remote ischemic postconditioning protects against crush-induced acute kidney injury via down-regulation of apoptosis and senescence

BACKGROUND

Acute renal failure due to crush syndrome is one of the leading causes of death in disasters. Ischemic Postconditioning (IPC) is a potentially effective strategy to protect against ischemic reperfusion injury, but a few studies noted its protective effect in crush induced acute kidney injury (AKI). Hence, this study investigated the optimal IPC strategy to prevent crush induced AKI and reveal related cellular mechanisms.

METHODS

The right lower extremities of rabbits were constantly compressed for 8 h and then performed five cycles of clamping and releasing the femoral artery and vein before depression using a clip. In terms of the duration of clamping and releasing, the animals were randomly divided into 5 groups, Control, IPC-5sec, IPC-30sec, IPC-1min, and IPC-5min groups; 6 rabbits for each group. Biomarkers of inflammation, renal function, renal tubular injury, and muscular injury, apoptosis, and cellular senescence in kidney were detected.

RESULTS

Six hours after decompression, the levels of Serum Creatine (SCr), Blood Urea Nitrogen (BUN), K+, and Interleukin-6 (IL-6) in IPC-1min and IPC-5min groups were lower than Control, with a statistically significant difference. The morphological study of Periodic Acid-Schiff (PAS) staining demonstrated that 6 h after decompression, IPC-1min can attenuate renal tubular damage renal tubule. Meanwhile, the level of Neutrophil Gelatinase-Associated Lipocalin (NGAL) in circulation in the IPC-30sec, IPC-1min, and IPC-5min groups was significantly decreased compared with the Control group, 2 h after decompression. On the other hand, the levels of serum Creatine Kinase (CK) and Myoglobin (Mb), and the morphological change of muscular damage detected by hematoxylin and eosin (H&E) staining in IPC-1min-treated group were significantly lower than Control group 6 hours after decompression. Further results of the cellular mechanism showed that the apoptotic markers of Terminal deoxynucleotidyl Transferase-mediated dUTP Nick End Labeling (TUNEL) and Caspase3 and the cell senescent markers of senescence-associated β-galactosidase (SA-β-Gal) and nuclear LAMNB1 have changed significantly in the IPC-1min group, compared with the control group.

CONCLUSIONS

Performing 5 cycles of 1-min IPC would be a convenient, time-saving, and effective method to prevent crush-induced AKI by attenuating the release of nephrotoxic substances after decompression and downregulation of the expression of apoptosis and cellular senescence biomarkers.

Effects of Plant-Derived Glycerol Monolaurate (GML) Additive on the Antioxidant Capacity, Anti-Inflammatory Ability, Muscle Nutritional Value, and Intestinal Flora of Hybrid Grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂)

In a context where the search for plant-derived additives is a hot topic, glycerol monolaurate (GML) was chosen as our subject to study its effect on grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂). Seven gradient levels of GML (0, 600, 1200, 1800, 2400, 3000, and 3600 mg/kg) were used for the experiment. Based on our experiments, 1800 mg/kg GML significantly increased the final body weight (FBW) and weight gain rate (WGR). GML increased the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreased malondialdehyde (MDA). Adding 1800 mg/kg GML also significantly increased the levels of lauric acid (C12:0) (LA), n-3 polyunsaturated fatty acids (PFA), and the n-6 PFA-to-n-3/n-6 ratio, while significantly decreasing the levels of saturated fatty acids (SFA). Dietary supplementation with GML significantly inhibited the expression of pro-inflammatory factors and reduced the occurrence of inflammation. GML improved intestinal flora and the abundance of beneficial bacteria (Bacillus, Psychrobacter, Acinetobacter, Acinetobacter, Stenotrophomonas, and Glutamicibacter). It provides a theoretical basis for the application of GML in aquafeed and greatly enhances the possibility of using GML in aquafeed. Based on the above experimental results, the optimum level of GML in grouper feed is 1800 mg/kg.

Cerebral protection by remote ischemic post-conditioning in patients with ischemic stroke: A systematic review and meta-analysis of randomized controlled trials

Background

There is evidence that remote limb ischemic postconditioning (RIPostC) can reduce ischemia-reperfusion injury (IRI) and improve the prognosis of patients with ischemic stroke. However, so far, only few relevant clinical studies have been conducted. Therefore, we carried out a meta-analysis of eligible randomized controlled trials to compare the RIPostC group with a control group (no intervention or sham surgery) in patients with ischemic stroke.

Methods

Four English-language publication databases, PubMed, Cochrane, Embase, and Web of Science, were systematically searched up to March 2022. The data were analyzed using Review Manager fixed-effects and random-effects models.

Results

A total of 12 studies were included, and 11 of those were analyzed quantitatively. Compared to controls, The RIPostC group showed significantly reduced NIHHS scores in patients with ischemic stroke, (MD: −1.09, 95% confidence interval [CI]: −1.60, −0.57, P < 0.0001) and improved patients' Montreal Cognitive Assessment (MoCA) scores, (MD: 1.89, 95% CI: 0.78, 3.00, P = 0.0009), Our results showed that RIPostC is safe, (RR = 0.81, 95%CI: 0.61, 1.08, P = 0.15).

Conclusion

Our meta-analysis showed that RIPostC is safe and effective and has a positive cerebral protective effect in patients with ischemic stroke, which is safe and effective, and future large-sample, multicenter trials are needed to validate the cerebral protective effect of RIPostC.

The Role of Pyroptosis and Autophagy in Ischemia Reperfusion Injury

Pyroptosis is a process of programmed cell death mediated by gasdermin (GSDM) found in recent years. In the process of pyroptosis, caspase-1 or caspase-11/4/5 is activated, which cleaves gasdermin D and separates its N-terminal pore-forming domain (PFD). The oligomers of PFD bind to the cell membrane and form macropores on the membrane, resulting in cell swelling and membrane rupture. Increasing evidence indicates that pyroptosis is involved in many diseases, including ischemia reperfusion injury. Autophagy is a highly conserved catabolic process in eukaryotic cells. It plays an important role in the survival and maintenance of cells by degrading organelles, proteins, and macromolecules in the cytoplasm and recycling degradation products. Increasing evidence shows that dysfunctional autophagy participates in many diseases. Recently, autophagy and pyroptosis have been reported to play a vital role in the process of ischemia/reperfusion injury, but the related mechanisms are not completely clear. Therefore, this article reviews the role of autophagy and pyroptosis in ischemia–reperfusion injury and analyzes the related mechanisms to provide a basis for future research.

Plicosepalus acacia Extract and Its Major Constituents, Methyl Gallate and Quercetin, Potentiate Therapeutic Angiogenesis in Diabetic Hind Limb Ischemia: HPTLC Quantification and LC-MS/MS Metabolic Profiling

Plicosepalus acacia (Fam. Loranthaceae) has been reported to possess hypoglycemic, antioxidant, antimicrobial, and anti-inflammatory effects. Liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) analysis revealed the presence of a high content of polyphenolic compounds that are attributed to the therapeutic effects of the crude extract. In addition, methyl gallate and quercetin were detected as major phytomedicinal agents at concentrations of 1.7% and 0.062 g%, respectively, using high-performance thin layer chromatography (HPTLC). The present study investigated the effect of the P. acacia extract and its isolated compounds, methyl gallate and quercetin, on hind limb ischemia induced in type 1 diabetic rats. Histopathological examination revealed that treatment with P. acacia extract, methyl gallate, and quercetin decreased degenerative changes and inflammation in the ischemic muscle. Further biochemical assessment of the hind limb tissue showed decreased oxidative stress, increased levels of nitric oxide and endothelial nitric oxide synthase (eNOS), and enhancement of the levels of heme oxygenase-1 (HO-1) and vascular endothelial growth factor (VEGF) in the groups treated with methyl gallate and quercetin. Expression levels of hypoxia inducible factor-1 alpha (HIF-1α), VEGF, fibroblast growth factor-2 (FGF-2), and miR-146a were upregulated in the muscle tissue of methyl gallate- and quercetin-treated groups along with downregulation of nuclear factor kappa B (NF-κB). In conclusion, P. acacia extract and its isolated compounds, methyl gallate and quercetin, mediated therapeutic angiogenesis in diabetic hind limb ischemia.