Pentoxifylline and Methylprednisolone Additively Alleviate Kidney Failure and Prolong Survival of Rats after Renal Warm Ischemia-Reperfusion

Effects of grape seed-derived proanthocyanidin B2 pretreatment on oxidative stress, endoplasmic reticulum stress and apoptosis of renal tubular epithelial cells in renal ischemia-reperfusion injury model of mice

PURPOSE

To investigate the effect of grape seed-derived proanthocyanidin B2 (GSPB2) pretreatment on acute renal ischemia-reperfusion injury model of mice.

METHODS

50 mice were divided into 5 groups: Sham group: mice were treated with right nephrectomy. GSPB2 group: GSPB2 was injected intraperitoneally 45 min before right nephrectomy. IRI group: right kidney was resected and the left renal arteriovenous vessel was blocked for 45 min. GSPB2 + IRI group: GSPB2 was intraperitoneally injected 45 min before IRI established. GSPB2 + BRU + IRI group: GSPB2 and brusatol (BRU) were injected intraperitoneally 45 min before IRI established. Creatinine and urea nitrogen of mice were detected, and the kidney morphology and pathological changes of each group were detected by HE staining, PAS staining and transmission electron microscopy. Expressions of Nrf2, HO-1, GRP78, CHOP, and cleaved-caspase3 were detected by immunofluorescence staining and western blotting.

RESULTS

Morphology and mitochondrial damages of kidney in GSPB2 + IRI group were significantly alleviated than those in IRI group. Expression levels of Nrf2 and HO-1 were significantly higher in GSPB2 + IRI group than those in IRI group. Expression levels of GRP78, CHOP and cleaved-caspase3 were significantly lower in GSPB2 + IRI group than those in IRI group. However, compared to GSPB2 + IRI group, protective effects of GSPB2 pretreatment were weakened in GSPB2 + BRU + IRI group.

CONCLUSIONS

GSPB2 pretreatment could alleviate oxidative stress damage and reduce apoptosis of renal tubular epithelial cells, which might be related to activating the antioxidant system, up-regulating the expression of Nrf2 and HO-1, inhibiting the expressions of GRP78, CHOP and cleaved-caspase3. However, the protective effect could be reversed by brusatol.

The polarization of M2 macrophages can be adjusted to alleviate renal injury by methylprednisolone in sepsis-AKI

Acute kidney injury in sepsis patients has an extreme mortality rate in clinical. It obviously seems that immune cells, for example, macrophages are involved with this process. Macrophages, as highly important immune cells, play a significant role in the development of human kidney diseases. But the specific role of macrophages in this process is still unclear. Under different timeline points, we surprisingly found that macrophages had the most dynamic changes in acute kidney injury immune cells. Based on macrophages' functions, they are primarily classified into M1 macrophages (pro-inflammatory) and M2 macrophages (anti-inflammatory). The polarization of M2 macrophages is closely associated with the seriousness of sepsis-induced kidney injury, but how to modulate their polarization to alleviate sepsis-associated renal damage remains unknown. We discovered that the polarization of M2 macrophages after methylprednisolone injection can significantly alleviate acute kidney injury by reducing secreted cytokine. This study suggests that the proportion of macrophage subtypes can be regulated by methylprednisolone to alleviate acute kidney injury in sepsis to provide a new sight for a clinical to provide a promising strategy for renal injury caused.

Pentoxifylline and thiamine ameliorate rhabdomyolysis-induced acute kidney injury in rats via suppressing TLR4/NF-κB and NLRP-3/caspase-1/gasdermin mediated-pyroptosis

Acute kidney injury (AKI) is a common complication of rhabdomyolysis (RM), a syndrome characterized by skeletal muscle damage resulting in renal tubular oxidative stress, inflammation, and activated toll like receptor-4 (TLR-4) and NOD-like receptor protein-3 (NLRP-3) inflammasome. Pyroptosis is a programmed cell death mediated by NLRP-3 leading to the activation of caspase-1 and gasdermin D (GSDMD), the hallmark of pyroptosis. This study aims to investigate the renoprotective effects of two antioxidants; pentoxifylline (PTX) and thiamine (TM) via targeting the aforementioned pathways. RM-AKI was induced in male Albino Wistar rats by intramuscular injection of glycerol (50% v/v, 10 ml/kg). PTX (100 mg/kg, oral) and TM (25 mg/kg, i.p) were administered for 12 days prior glycerol injection and continued for 3 days following induction of RM-AKI. Serum creatinine, blood urea nitrogen (BUN), creatin kinase, lipid peroxides, total antioxidant activity, inflammatory markers (tumor necrosis factor-α, interleukin-1β, and nuclear factor kappa B), TLR4, NLRP-3, caspase-1, GSDMD and c-myc (an apoptotic marker) were estimated. Compared to AKI model, co-administered drugs revealed a significant improvement in renal function and pathology as indicated by the reduction in serum creatinine, BUN and protein cast accumulation. The elevations of oxidative stress, and inflammatory markers as well as the over-expression of c-myc were alleviated. Protein levels of TLR4, NLRP3, cleaved caspase-1, and GSDMD were significantly elevated in RM-AKI model, and this elevation was attenuated by the tested drugs. In conclusion, PTX and TM could be a potential renoprotective approach for patients with RM through targeting TLR4/NF-κB and NLRP-3/caspase-1/gasdermin mediated-pyroptosis pathways.

Evaluation of Nrf2/ARE Signaling Pathway in the Presence of Pentoxifylline as a Cryoprotectant in Mouse Spermatogonial Stem Cells

The process of spermatogonial stem cell cryopreservation (SSCs) in young male cancer survivors is associated with increased reactive oxygen species (ROS), DNA fragmentation, apoptosis, decreased cell activity, and finally reduced fertility of SSCs. Therefore, it is necessary to add cryoprotectants to the freezing medium to minimize the injuries associated with cryopreservation. In addition, the Nrf2/ARE pathway is a main cellular pathway that regulates the antioxidant defense system. The purpose of this study was to evaluate the cryoprotective effect of pentoxifylline (PTX) on SSCs after freezing-thawing through the Nrf2/ARE pathway. SSCs extracted from neonatal mice testes were isolated and their purity was measured by flow cytometry with GDNF family receptor alpha-1 (GFRα1) and inhibitor of differentiation 4 (ID4). After culturing, the cells were frozen in different groups for 1 month. After freezing-thawing, cell viability, colonization rate, and intracellular ROS, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were evaluated. Quantitative real-time polymerase chain reaction and western blotting were done to assess the expression levels of Nrf2, Keap-1, PI3K, and AKT genes and proteins. The survival and colonization rates of SSCs, SOD, and CAT levels, and Nrf2, PI3K, and AKT expression levels were significantly higher in the PTX group compared with the other cryopreservation groups. The Keap-1 expression level and the ROS and MDA production levels also decreased significantly in the PTX group (p-value <0.05). According to our findings, PTX can activate the antioxidant defense through the Nrf2/ARE signaling pathway; therefore, it could be a suitable cryoprotectant candidate for freezing and long-term storage of SSCs in the clinical setting.

Implications of miRNAs on TGF-β/TAK1/mTOR pathway in mediating the renoprotective effects of pentoxifylline against cisplatin-induced nephrotoxicity in rats

Cisplatin (CIS)-mediated nephrotoxicity is induced via transforming growth factor-beta (TGF-β) and TGF-β-activated kinase (TAK1). TGF-β and TAK1 are known to interact with microRNA-let-7b and microRNA-26b, respectively. Additionally, TGF-β1 is reported to down-regulate the autophagy marker microtubule-associated protein 1 light chain 3-II (LC3-II) through upregulation of microRNA-34a. Pentoxifylline (PTX) anti-inflammatory effects are mediated via suppressing TGF-β and regulating mammalian target of rapamycin (mTOR). The current study aimed to investigate the involvement of microRNAs let-7b, 26b, and 34a, and the modulating impact of PTX on CIS-induced nephrotoxicity. Moreover, we aimed at examining the ability of PTX to interact with TGF-β receptor-1 (TGFβR-1), and TAK1, and examine its ability to downgrade the previously reported toxicities. Hence, the expression of the aforementioned microRNAs, and protein levels of TGFβR-1, TGF-β1, TAK1, mTOR, LC3-II, and NF-κB were assessed. Molecular docking studies of PTX on TGFβR-1 and TAK1 were also executed. CIS induced TGF-β1, with down-regulation of microRNA-let-7b and -26b, and up-regulation of microRNA-34a. TGFβR-1, TAK1, and mTOR levels were increased, while LC3-II level was decreased. PTX significantly protected renal cells against CIS-induced changes as indicated by reverting the level of the investigated parameters, while exhibiting an antagonistic effect on TGFβR-1 and TAK1. Our results postulate a possible role of epigenetic regulation of CIS-induced nephrotoxicity through the investigated microRNAs proposing them as potential future targets for controlling this serious toxicity. PTX was able to shield CIS-induced toxicity possibly through blocking TGF-β pathway, while promoting autophagy in a TAK1 independent manner with the involvement of the examined microRNAs.