Human umbilical cord mesenchymal stem cell exosomes alleviate sepsis-associated acute kidney injury via regulating microRNA-146b expression.

Human umbilical cord mesenchymal stem cell-derived exosomes (HucMSC-Ex) are a promising tool for the repair of acute kidney injury (AKI) caused by cisplatin and ischemia/reperfusion. However, the roles of hucMSC-Ex in sepsis-associated AKI repair and its mechanism are largely unknown. Hence, we constructed a sepsis model through cecal ligation and puncture (CLP), testing the benefits of hucMSC-Ex in the sepsis in terms of survival rate, serum renal markers levels, morphological changes and apoptosis. Immunohistochemistry staining and immunofluorescence assay were used to investigate the role of NF-κB activity in the repair of sepsis-associated AKI with hucMSC-Ex. HK-2 cells were transfected with microRNA-146b (miR-146b) mimics and inhibitors, respectively, and the regulatory effect of miR-146b on NF-κB activity was studied. We found that hucMSC-Ex treatment significantly decreased the serum creatinine (Cr) and blood urea nitrogen (BUN) levels, ameliorated the morphological damage and inhibited renal tubular cells apoptosis. More importantly, the survival rate at 72 h was 28% in CLP group and 45% in hucMSC-Ex group, respectively. Treatment with hucMSC-Ex improved survival in mice with sepsis. These effects of hucMSC-Ex were mediated by the inhibition of NF-κB activity and the lessening of pro-inflammatory response. Furthermore, hucMSC-Ex significantly increased miR-146b expression in kidney tissues. Conversely, interleukin (IL)-1 receptor-associated kinase (IRAK1) level, which is the target gene of miR-146b, clearly decreased in hucMSC-Ex group. In brief, this study showed that treatment with hucMSC-Ex decreased IRAK1 expression through the up-regulation of miR-146b level, led to the inhibition of NF-κB activity, and eventually alleviated sepsis-associated AKI and improved survival in mice with sepsis. HucMSC-Ex may be a novel therapeutic agent for the reduction of sepsis-associated AKI.

Cystamine slows but not inverses the progression of monocrotaline-induced pulmonary arterial hypertension in rats.

Tissue transglutaminase (TG2) plays an important role in pulmonary arterial hypertension (PAH). Previous research indicate that TG2 and protein serotonylation catalyzed by TG2 are upregulated in PAH. Serotonin transporter inhibitor fluoxetine ameliorates PAH via inhibition of protein serotonylation. It is still unknown whether PAH is inhibited through direct inhibition of TG2. Therefore, the present study aimed to investigate the effects of TG2 inhibitor cystamine on monocrotaline-induced PAH in rats. Rats were treated with monocrotaline (60 mg·kg-1, i.p.) in combination with or without cystamine (20, 40 mg·kg-1·day-1, p.o.). The results showed that compared with monocrotaline alone, combination of monocrotaline with cystamine (40 mg·kg-1·day-1, p.o.) relieved right ventricle hypertrophy, inhibited pulmonary arteriolar remodeling, and downregulated protein expression of TG2, phosphorylated protein kinase B (Akt), and extracellular regulated protein kinase (ERK) at day 21. However, except for TG2 expression, these changes were not significantly inhibited by cystamine at day 35. In addition, cystamine dose-dependently enhanced the survival rate of rats injected with monocrotaline at day 35. The findings suggest that cystamine slows but not reverses monocrotaline-induced PAH in rats, which was largely associated with the inhibition of TG2 protein expression and Akt and ERK activation.

hucMSC-sEVs-Derived 14-3-3ζ Serves as a Bridge between YAP and Autophagy in Diabetic Kidney Disease.

As nanoscale membranous vesicles, human umbilical cord mesenchymal stem cell-derived small extracellular vesicles (hucMSC-sEVs) have attracted extensive attention in the field of tissue regeneration. Under the premise that the mechanisms of hucMSC-sEVs on the treatment of diabetic kidney disease (DKD) have not been revealed clearly, we constructed DKD rat model with success. After tail vein injection, hucMSC-sEVs effectively reduced blood glucose, maintained body weight and improved renal function in DKD rats. Notably, we found that hucMSC-sEVs suppressed YAP expression in renal cortical regions. Further in vitro experiments, we confirmed that the expression of YAP in the nucleus of renal podocytes was increased, and the level of autophagy was inhibited in the high-glucose environment, which could be reversed by intervention with hucMSC-sEVs. We screened out the key protein 14-3-3ζ, which could not only promote YAP cytoplasmic retention instead of entering the nucleus, but also enhance the level of autophagy in the cytoplasm. Ultimately, excessive YAP protein was removed by autophagy, a classic way of protein degradation. In conclusion, our study provides new strategies for the prevention of DKD and proposes the possibility of hucMSC-sEVs becoming a new treatment for DKD in the future.

Platelet-rich plasma promotes MSCs exosomes paracrine to repair acute kidney injury via AKT/Rab27 pathway.

Acute kidney injury (AKI) is defined by rapid deterioration of renal function, and is a common complication in hospitalized patients. Among the recent therapeutic options, mesenchymal stem cells (MSCs) are considered a promising therapeutic strategy for damaged tissue repair. Platelet rich plasma (PRP) regulates mesenchymal cells to repair tissue damage through the release of growth factors. In this study, we proposed a possible therapeutic use of MSCs stimulated by platelet-rich plasma (PRP-MSCs) in a glycerin-induced AKI murine model. In vivo and in vitro studies, showed that PRP-MSCs could significantly attenuate serum blood urea nitrogen and creatinine levels, and reverse the histopathological kidney damage. PRP-MSCs treatment reduced renal tubular cell apoptosis stimulated by glycerin. We confirmed that PRP promoted the proliferation and reinforced the stemness of MSCs by inducing YAP nucleus expression, and that PRP promoted MSCs exosomes in a paracrine manner to repair AKI through an activated AKT/Rab27 pathway. Our results revealed that the PRP stimulated MSCs paracrine pathway could effectively alleviate glycerin-induced AKI. Therefore, PRP pretreatment may be a new method to improve the therapeutic effect of MSCs.

Neuroprotective effect of sodium ferulate and signal transduction mechanisms in the aged rat hippocampus.

AIM: To investigate whether the age-related increase in interleukin-1beta (IL-1beta) and c-Jun N-terminal kinases (JNK) pathway was coupled with a decrease in cell survival signaling pathways and whether sodium ferulate (SF) treatment was effective in preventing these age-associated changes. METHODS: Groups of young and aged rats were fed for 4 weeks on a diet enriched in SF (100 mg/kg and 200 mg/kg per day). At the end of the period of dietary manipulation, Western blotting analysis was used to determine the expressions of IL-1beta, phosphorylated mitogen-activated protein kinase kinase (MKK)4, phospho-JNK, phospho-c-Jun, phosphorylated extracellular signal-regulated kinase (ERK1/2), phospho-MEK, phospho-Akt, phosphorylated ribosomal protein S6 protein kinase (p70S6K), and activated caspase-3 and caspase-7. Nissl staining was used to observe the morphological change in hippocampal CA1 regions. Immunohistochemical techniques for glial fibrillary acidic protein (GFAP) and integrin alphaM (OX-42) were used to determine the astrocyte and microglia activation. RESULTS: IL-1beta protein levels, and phospho-MKK4, phospho-JNK1/2, and phospho-c-Jun were significantly enhanced in hippocampus prepared from age-matched control rats. Increased IL-1beta production and JNK1/2 activation was accompanied by downregulation of MEK/ERK1/2 pathway and Akt/p70S6K pathway, leading to cell apoptosis assessed by activation of caspase-3. Significantly, treatment of aged rats with SF (100 mg/kg and 200 mg/kg per day) for 4 weeks prevented the agerelated increase in IL-1beta and IL-1beta-induced JNK signaling pathway and also the age-related changes in ERK and Akt kinase. CONCLUSION: SF plays neuroprotective roles through suppression of IL-1beta and IL-1beta-induced JNK signaling and upregulation of MEK/ERK1/2 and Akt/p70S6K survival pathways.

HucMSC exosomes-delivered 14-3-3ζ enhanced autophagy via modulation of ATG16L in preventing cisplatin-induced acute kidney injury.

The clinical application of cisplatin is restricted by its side effects of nephrotoxicity. Human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-ex) have an important effect in tissue injury repair. Our previous work discovered that pretreatment with human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-ex) alleviated cisplatin-induced acute kidney injury (AKI) by activating autophagy both in vitro and in vivo. In this study, we further explored the mechanisms of hucMSC-ex in autophagy for preventing cisplatin-induced nephrotoxicity. We discovered that 14-3-3ζ was contained in hucMSC-ex, and knockdown and overexpression 14-3-3ζ reduced and enhanced the autophagic activity respectively. Furthermore, Knockdown of 14-3-3ζ alleviated the preventive effect of hucMSC-ex. In contrast, overexpression of 14-3-3ζ enhanced the effect. Further results confirmed that hucMSC-ex increased ATG16L expression and that 14-3-3ζ interacted with ATG16L, promoting the localization of ATG16L at autophagosome precursors. In this study, we revealed that hucMSC-ex-delivered 14-3-3ζ interacted with ATG16L to activate autophagy. Our findings suggest that 14-3-3ζ is a novel mechanism for MSC-exosomes-activated autophagy and provides a new strategy for the prevention of cisplatin-induced nephrotoxicity.

MicroRNA-146b, a Sensitive Indicator of Mesenchymal Stem Cell Repair of Acute Renal Injury.

: The role of mesenchymal stem cells (MSCs) in kidney injury repair has been studied widely. However, the underlying molecular mechanism remains unclear. We profiled the altered microRNAs in renal tissues from cisplatin-induced acute kidney injury (AKI) rats treated with or without rat bone marrow MSCs (rMSCs). We observed that microRNA-146b (miR-146b) expression was considerably upregulated in renal tissues from AKI rats compared with that in healthy rats, and the expression decreased following MSC treatment after cisplatin administration. At the early stage of AKI, serum miR-146b levels exhibited a rapid increase that was even faster than that of two conventional renal function indexes: serum creatinine and blood urea nitrogen levels. Furthermore, the serum miR-146b levels in AKI patients were higher than those in healthy people. In vitro exposure to cisplatin also increased miR-146b expression in renal tubular epithelial cells (TECs). miR-146b knockdown protected renal TECs from cisplatin-induced apoptosis and promoted their proliferation. Moreover, ErbB4 was identified as a direct target of miR-146b, and miR-146b inhibition induced ErbB4 expression, resulting in enhanced proliferation of injured renal TECs. In addition, restoration by rMSCs could be controlled through ErbB4 downregulation. In conclusion, elevated miR-146b expression contributes to cisplatin-induced AKI, partly through ErbB4 downregulation. miR-146b might be an early biomarker for AKI, and miR-146b inhibition could be a novel strategy for AKI treatment. SIGNIFICANCE: The present study found that microRNA-146b (miR-146b) might be a novel biomarker for acute kidney injury and an indicator for its recovery after treatment with mesenchymal stem cells (MSCs). The results showed that in acute kidney injury induced by cisplatin, miR-146b in serum increased more quickly than did the usual indexes of kidney injury and decreased with restoration of MSCs. In addition, inhibition of miR-146b could ameliorate the apoptosis induced by cisplatin and potentially improve the proliferation by freeing ErbB4 and its downstream proteins.