Protective effects of N(2)‑L‑alanyl‑L‑glutamine mediated by the JAK2/STAT3 signaling pathway on myocardial ischemia reperfusion

Cryptotanshinone alleviates myocardial ischemia and reperfusion injury in rats to mitigate ER stress-dependent apoptosis by modulating the JAK1/STAT3 axis

OBJECTIVE

Myocardial ischemia is the stoppage or insufficiency of blood flow to the myocardium, depriving cells of oxygen supply which leads to their apoptosis or death. Currently, the management of patients has improved, making it possible to reduce myocardial infarction injury with new strategies of reperfusion and pharmacologic treatment.

METHODS

A rat model of myocardial ischemia and reperfusion injury (MIRI) was created and subjected to cryptotanshinone (CRY) with or without JAK1 inhibitor filgotinib (FILGO) treatment. H&E staining was used for histopathologic evaluation of heart injury, and TTC staining was employed for evaluation of the infarct size. Western blotting and immunofluorescence were used to measure the protein expression and qRT-PCR for determining mRNA expression.

RESULTS

CRY significantly reduced the area of the infarct, the number of apoptotic cells, and the concentrations of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) induced by ischemia/reperfusion (I/R). Subsequent analysis showed that CRY repressed the expression of caspase-12, CHOP, and GRP78, but enhanced the phosphorylation of JAK and STAT3. However, FILGO treatment markedly abolished the beneficial effect of CRY pretreatment on cardiomyocyte damage, apoptosis, cardiac function, and inhibition of endoplasmic reticulum stress (ERS)-dependent apoptosis marker proteins.

CONCLUSION

CRY may alleviate MIRI by inhibiting ERS-dependent apoptosis by activating the JAK1/STAT3 signaling pathway.

Alanyl-Glutamine Protects against Lipopolysaccharide-Induced Liver Injury in Mice via Alleviating Oxidative Stress, Inhibiting Inflammation, and Regulating Autophagy

Acute liver injury is a worldwide problem with a high rate of morbidity and mortality, and effective pharmacological therapies are still urgently needed. Alanyl-glutamine (Ala-Gln), a dipeptide formed from L-alanine and L-glutamine, is known as a protective compound that is involved in various tissue injuries, but there are limited reports regarding the effects of Ala-Gln in acute liver injury. This present study aimed to investigate the protective effects of Ala-Gln in lipopolysaccharide (LPS)-induced acute liver injury in mice, with a focus on inflammatory responses and oxidative stress. The acute liver injury induced using LPS (50 μg/kg) and D-galactosamine (D-Gal) (400 mg/kg) stimulation in mice was significantly attenuated after Ala-Gln treatment (500 and 1500 mg/kg), as evidenced by reduced plasma alanine transaminase (ALT) (p < 0.01, p < 0.001), aspartate transaminase (AST) (p < 0.05, p < 0.001), and lactate dehydrogenase (LDH) (p < 0.01, p < 0.001) levels, and accompanied by improved histopathological changes. In addition, LPS/D-Gal-induced hepatic apoptosis was also alleviated by Ala-Gln administration, as shown by a greatly decreased ratio of TUNEL-positive hepatocytes, from approximately 10% to 2%, and markedly reduced protein levels of cleaved caspase-3 (p < 0.05, p < 0.001) in liver. Moreover, we found that LPS/D-Gal-triggered oxidative stress was suppressed after Ala-Gln treatment, the effect of which might be dependent on the elevation of SOD and GPX activities, and on GSH levels in liver. Interestingly, we observed that Ala-Gln clearly inhibited LPS/D-Gal exposure-induced macrophage accumulation and the production of proinflammatory factors in the liver. Furthermore, Ala-Gln greatly regulated autophagy in the liver in LPS/D-Gal-treated mice. Using RAW264.7 cells, we confirmed the anti-inflammatory role of Ala-Gln-targeting macrophages.

Characterization of novel lncRNAs in upper thoracic spinal cords of rats with myocardial ischemia-reperfusion injuries

Myocardial ischemia-reperfusion injury (MIRI) is a significant problem in clinical cardiology, and refers to a more serious myocardial injury caused by blood recanalization after a period of myocardial ischemia, as compared with injury caused by vascular occlusion. The spinal cord, as the primary afferent and efferent center of cardiac sensory and sympathetic nerve fibres, has received increased attention in recent years with regards to the regulation of MIRIs. Previous studies have revealed that MIRI has a strong correlation with the abnormal expression of long non-coding (lnc)RNAs in the myocardium; however, there are limited reports on the effects of the altered expression of lncRNAs in the spinal cord following MIRI. To investigate the expression patterns of lncRNAs in the spinal cord after MIRI and their potential role in the early stage of reperfusion, a MIRI model was established in rats. After 30 min of myocardial ischemia and 2 h of reperfusion, the upper thoracic spinal cord tissues were immediately dissected and isolated. lncRNAs and mRNAs in spinal cord tissues were screened using transcriptome sequencing technology, and the expression of several highly deregulated mRNAs, including Frs3, Zfp52, Dnajc6, Nedd4l, Tep1, Myef2, Tgfbr1, Fgf12, Mef2c, Tfdp1 and lncRNA, including ENSRNOT00000080713, ENSRNOT00000090564, ENSRNOT00000082588, ENSRNOT00000091080, ENSRNOT00000091570, ENSRNOT00000087777, ENSRNOT00000082061, ENSRNOT00000091108, ENSRNOT00000087028, ENSRNOT00000086475, were further validated via reverse transcription-quantitative PCR. The number of altered expressed lncRNAs was 126, among which there were 41 upregulated probe sets and 85 downregulated sets. A total of 470 mRNAs were differentially expressed, in which 231 probe sets were upregulated and 239 were downregulated. Gene Ontology analysis indicated that dysregulated transcripts related to biological processes were mainly associated with ‘cell-cell signaling’. Moreover, pathway analysis demonstrated significant changes in the ‘PI3K/Akt signaling pathway’ and the ‘p53 signaling pathway’. Thus, the altered expression of lncRNAs in the spinal cord may be of considerable importance in the process of MIRI. The present results could provide an insight into the potential roles and mechanism of lncRNAs during the early stage of reperfusion.

Cinnamaldehyde protects against rat intestinal ischemia/reperfusion injuries by synergistic inhibition of NF-κB and p53

Our preliminary study shows that cinnamaldehyde (CA) could protect against intestinal ischemia/reperfusion (I/R) injuries, in which p53 and NF-κB p65 play a synergistic role. In this study, we conducted in vivo and in vitro experiments to verify this proposal. SD rats were pretreated with CA (10 or 40 mg · kg⁻¹ · d⁻¹, ig) for 3 days, then subjected to 1 h mesenteric ischemia followed by 2 h reperfusion. CA pretreatment dose-dependently ameliorated morphological damage and reduced inflammation evidenced by decreased TNF-α, IL-1β, and IL-6 levels and MPO activity in I/R-treated intestinal tissues. CA pretreatment also attenuated oxidative stress through restoring SOD, GSH, LDH, and MDA levels in I/R-treated intestinal tissues. Furthermore, CA pretreatment significantly reduced the expression of inflammation/apoptosis-related NF-κB p65, IKKβ, IK-α, and NF-κB p50, and downregulated apoptotic protein expression including p53, Bax, caspase-9 and caspase-3, and restoring Bcl-2, in I/R-treated intestinal tissues. We pretreated IEC-6 cells in vitro with CA for 24 h, followed by 4 h hypoxia and 3 h reoxygenation (H/R) incubation. Pretreatment with CA (3.125, 6.25, and 12.5 μmol · L⁻¹) significantly reversed H/R-induced reduction of IEC-6 cell viability. CA pretreatment significantly suppressed oxidative stress, NF-κB activation and apoptosis in H/R-treated IEC-6 cells. Moreover, CA pretreatment significantly reversed mitochondrial dysfunction in H/R-treated IEC-6 cells. CA pretreatment inhibited the nuclear translocation of p53 and NF-κB p65 in H/R-treated IEC-6 cells. Double knockdown or overexpression of p53 and NF-κB p65 caused a synergistic reduction or elevation of p53 compared with knockdown or overexpression of p53 or NF-κB p65 alone. In H/R-treated IEC-6 cells with double knockdown or overexpression of NF-κB p65 and p53, CA pretreatment caused neither further decrease nor increase of NF-κB p65 or p53 expression, suggesting that CA-induced synergistic inhibition on both NF-κB and p53 played a key role in ameliorating intestinal I/R injuries. Finally, we used immunoprecipitation assay to demonstrate an interaction between p53 and NF-κB p65, showing the basis for CA-induced synergistic inhibition. Our results provide valuable information for further studies.

Protective Effects Oncorneal Endothelium During Intracameral Irrigation Using N-(2)-l-alanyl-l-Glutamine

Corneal endothelial disease is a global sight-threatening disease, and corneal transplantation using donor corneas remains the sole therapeutic option. A previous work demonstrated that N (2)-alanyl-glutamine (Ala-Gln) protected against apoptosis and cellular stress, and maintained intestinal tissue integrity. In this pursuit, the present study aimed to examine the effect of Ala-Gln in the protection of the corneal endothelium and expand its range of potential clinical applications. Mice in the control group were intracamerally irrigated with Ringers lactate injection, whereas those in the experimental group were irrigated with Ringers lactate injection containing Ala-Gln. The mean intraocular pressure increased to 44 ± 3.5 mm Hg during intracameral irrigation (normal range 10.2 ± 0.4 mmHg). In vivo confocal microscopy results showed that the addition of Ala-Gln protected the morphology, structure, and density of the corneal endothelial cells. Optical Coherence Tomography (OCT) measurements showed that corneal thickness was not significantly different between the two groups, because of the immediate corneal edema after irrigation, but the addition of Ala-Gln obviously promoted the recovery of the corneal edema. Scanning electron microscopy indicated that the corneal endothelial cells were severely ruptured and exfoliated in the Ringer’s group accompanied with cellular edema, when compared with the Ala-Gln group. The intracameral irrigation using Ala-Gln protected the structure and expression of cytoskeleton and Na-K-ATPase, which exhibited a regular distribution and significantly increased expression in comparison to Ringer’s group. Furthermore, Ala-Gln maintained the mitochondrial morphology and increased the activity of mitochondria. Moreover, transmission electron microscopy showed that intracameral irrigation of Ala-Gln reversed the ultrastructural changes induced by the acute ocular hypertension in mice. Our study demonstrates that the intracameral irrigation of Ala-Gln effectively maintained the corneal endothelial pump function and barrier function by protecting the mitochondrial function and preventing the rearrangement of cytoskeleton in acute ocular hypertension in mice.

Apigenin Alleviates Myocardial Reperfusion Injury in Rats by Downregulating miR-15b

Background

We investigated whether apigenin could mitigate myocardial reperfusion injury in rats, and a possible mechanism was proposed.

Material/Methods

The I-R injury model was established in rats along with a sham group as control, and the expressions of microRNA-15b (miR-15b), JAK2, and p-JAK2 in the myocardia of the 2 groups were detected. Apoptosis and reactive oxygen species (ROS) were also detected. Rats in the I-R injury model were divided into 3 groups in vivo: the 1I-R group, the 2I-R+solvent group, and the 3I-R+apigenin group. Expression of miR-15b, JAK2, p-JAK2, STAT3, and p-STAT3 in the myocardia of the 3 groups were detected. ROS content, apoptosis, MDA content, SOD, and CAT activities were detected. Rat myocardial H9C2 cells were cultured in vitro and divided into 5 treatment groups in vitro; expressions of miR-15b, JAK2, p-JAK2, STAT3, and p-STAT3 in H9C2 cells were detected, and the apoptosis and ROS content were detected by flow cytometry.

Results

We found that the increased miR-15b expression during myocardial I-R injury in rats downregulated the expression of JAK2 and activity of the JAK2-STAT3 pathway, promoted myocardial apoptosis and ROS production, and aggravated myocardial I-R injury. Apigenin treatment can downregulate miR-15b expression, increase the expression of JAK2 and the activity of JAK2-STAT3 pathway, reduce myocardial apoptosis and ROS production, and alleviate myocardial I-R injury.

Conclusions

Api treatment downregulated the expression of miR-15b and upregulated the expression of JAK2 and the activity of the JAK2-STAT3 pathway, thereby alleviating myocardial I-R injury, cardiomyocyte apoptosis, and ROS production in vitro.