Autophagy: A new treatment strategy for MSC-based therapy in acute kidney injury (Review)

PTEN-induced kinase 1 enhances the reparative effects of bone marrow mesenchymal stromal cells on mice with renal ischaemia/reperfusion-induced acute kidney injury

Acute kidney injury (AKI) is a common severe acute syndrome caused by multiple factors and is characterized by a rapid decline in renal function during a short period. Bone marrow mesenchymal stromal cells (BMSCs) are effective in treating AKI. However, the mechanism of their beneficial effects remains unclear. PTEN-induced kinase 1 (PINK1) may play an important role in kidney tissue repair. In this study, we explored the effect of PINK1 overexpression on enhancing BMSC-mediated repair of AKI. In this study, ischaemia/reperfusion-induced AKI (IRI-AKI) in mice and a hypoxia-reoxygenation model in cells were established, and the indices were examined by pathology and immunology experiments. After ischaemia/reperfusion, PINK1 overexpression reduced apoptosis in injured kidney tissue cell, decreased T lymphocyte infiltration, increased macrophage infiltration, and alleviated the inflammatory response. PINK1 relieved the stress response of BMSCs and renal tubular epithelial cells (RTECs), reduced apoptosis, altered the release of inflammatory factors, and reduced the proliferation of peripheral blood mononuclear cells (PBMCs). In conclusion, BMSCs and RTECs undergo stress responses in response to hypoxia, inflammation and other conditions, and overexpressing PINK1 in BMSCs could enhance their ability to resist these stress reactions. Furthermore, PINK1 overexpression can regulate the distribution of immune cells and improve the inflammatory response. The regulation of mitochondrial autophagy during IRI-AKI maintains mitochondrial homeostasis and protects renal function. The results of this study provide new strategies and experimental evidence for BMSC-mediated repair of IRI-AKI.

The protective effects of exogenous spermine on renal ischemia-reperfusion injury in rats

Background

To investigate the protective effects of exogenous spermine on renal ischemia-reperfusion injury in rats.

Methods

(I) Different doses of spermine were injected into rats to determine the safe dose on the kidneys. Kidney toxicity was assessed by hematoxylin and eosin (HE) staining of kidney tissue and enzyme-linked immunosorbent assay (ELISA) detection of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) in the venous blood. (II) A rat model of renal ischemia-reperfusion injury was established. Different doses of spermine were injected into the rats through the tail vein 30 minutes before and 3 days after the establishment of the model. Blood samples and kidney tissues were collected and renal injury was assessed via HE staining of the renal tissue, detection of apoptosis using the TUNEL assay, and detection of NGAL and KIM-1 in blood samples using ELISA. (III) Human HK-2 renal tubular epithelial cells were cultured under hypoxia/reoxygenation conditions. To evaluate the protective effects of spermine, apoptosis was assessed by flow cytometry and TUNEL assay. The mechanisms underlying the effects of spermine were studied using Western blot analyses.

Results

At spermine concentrations below 200 µM (2 mL/kg body weight), no significant damage to the kidney was observed by HE staining, and there was no significant difference in NGAL and KIM-1 levels between rats treated with spermine and control rats (P<0.05). At spermine doses below 200 µM, HE staining showed that the degree of renal ischemia-reperfusion injury was gradually alleviated with increasing doses of spermine. TUNEL assays demonstrated that spermine reduced the apoptosis of renal tissue, and increasing doses of spermine gradually decreased the levels of NGAL and KIM-1 in the blood compared with the control group (P<0.05). Western blot analysis revealed that spermine increased the expression of pro-caspase9, phosphorylated protein kinase B (p-Akt), hypoxia-inducible factor 1 alpha (HIF-1α), B cell lymphoma 2 (Bcl-2), and Bcl2 interacting protein 3 (BNIP3), and decreased the expression of cleaved caspase-3, Bax and cytochrome C compared to control cells.

Conclusions

Exogenous spermine exerted a protective effect on renal ischemia-reperfusion injury in rats by inhibiting the apoptosis of renal tubular epithelial cells.

Autophagy and Inflammation Regulation in Acute Kidney Injury

Autophagy at an appropriate juncture in the cell cycle exerts protective effects in acute kidney injury (AKI), whereas abnormal autophagy may lead to cell death. Inflammatory response plays a pivotal role in the pathophysiological process of kidney injury and repair during AKI. Several studies have reported an interaction between autophagy and inflammation in the pathogenesis of AKI. This review outlines recent advances in the investigation of the role of autophagy in inflammatory response regulation based on the following aspects. (1) Autophagy inhibits inflammatory responses induced in AKI through the regulation of mTOR and AMPK pathways and the inhibition of inflammasomes activation. (2) Autophagy can also help in the regulation of inflammatory responses through the nuclear factor kappa B pathway, which is beneficial to the recovery of kidney tissues. These studies reviewed here provide better insight into the mechanisms underlying the protective effects of the autophagy-inflammatory pathway. Through this review, we suggest that the autophagy-inflammatory pathway may serve as an alternative target for the treatment of AKI.

IL10-modified Human Mesenchymal Stem Cells inhibit Pancreatic Cancer growth through Angiogenesis Inhibition

In the present study, we constructed the recombinant plasmid IL10-PEGFP-C1 and successfully transfected into human mesenchymal stem cells. After culturing for 72 h, the levels of IL6 and TNF-α in the supernatant of the MSCs-IL10 group were significantly lower than the vector group and the control group (17.6 ± 0.68vs73.8 ± 0.8 and 74.4 ± 1.5) µg/L and (65.05 ± 3.8 vs 203.2 ± 2.4 and 201.3 ± 3.7) µg/L, respectively (p < 0.001) .The animal experiments showed that the volume of subcutaneous tumors in the MSCs-IL10 group in vivo was a significantly less level compared to that in MSC control and the blank control groups (76.84 ± 20.11) mm³ vs (518. 344 ± 48.66) mm³, (576.99± 49.88) mm³, (P < 0. 05) and they have a longer life time. Further we found the mass concentrations of IL6 and TNF-α in the blood serum of MSC-IL10 group were lower than the vector group and the control group (64.42 ± 10.9 vs120.83 ± 15.52 and 122.65 ± 13.71) and (40.05 ± 5.63 vs 126.78 ±1.89 and 105.83 ± 2.16) µg/L respectively (p < 0.001). CD31 immunohistochemistry and alginate encapsulation experiments showed tumor angiogenesis were inhibited in MSCs-IL10 group in comparison to the control and vector group (P < 0.001), FITC-labeled dextran intake was also lower than the other groups (P < 0.01). Collectively, this study suggested IL10 could inhibit the growth of the transplanted tumor in vivo and prolong survival of mice, and the primary mechanism may be the indirect inhibition of pro-inflammatory cytokines IL6 and TNF-α secretion and tumor angiogenesis formation.

Unique Triterpenoid of Jujube Root Protects Cisplatin-induced Damage in Kidney Epithelial LLC-PK1 Cells via Autophagy Regulation

Chronic exposure to cisplatin is associated with irreversible kidney impairment. In this present study, we explored the protective effects of 3-dehydroxyceanothetric acid 2-methyl ester (3DC2ME) isolated from roots of jujube (Ziziphus jujuba, Rhamnaceae) against cisplatin-induced damage in vitro. In kidney epithelial LLC-PK1 cells, western blotting and staining with specific autophagy epifluorescent dye CytoID were used to determine the molecular pathways involving autophagy. Treatment with 3DC2ME reduced the increased Cyto-ID-stained autophagic vesicles and reversed the protein expressions of 5' AMP-activated protein kinase subunit β-1 (AMPK)/mammalian target of rapamycin (mTOR)-dependent signaling pathway in cisplatin-induced cell death. Additionally, treatment with autophagy inhibitor 3-methyladenine (3-MA) and with or without 3DC2ME attenuated the cisplatin-induced apoptosis. Although further research is necessary to substantiate the effects, we evaluated the potential mechanism of action of 3DC2ME as an adjuvant for cancer patients.