Maternal endotoxemia induces renal collagen deposition in adult offspring: Role of NADPH oxidase/TGF-β1/MMP-2 signaling pathway

Perinatal Oxidative Stress and Kidney Health: Bridging the Gap between Animal Models and Clinical Reality

Oxidative stress arises when the generation of reactive oxygen species or reactive nitrogen species overwhelms antioxidant systems. Developing kidneys are vulnerable to oxidative stress, resulting in adult kidney disease. Oxidative stress in fetuses and neonates can be evaluated by assessing various biomarkers. Using animal models, our knowledge of oxidative-stress-related renal programming, the molecular mechanisms underlying renal programming, and preventive interventions to avert kidney disease has grown enormously. This comprehensive review provides an overview of the impact of perinatal oxidative stress on renal programming, the implications of antioxidant strategies on the prevention of kidney disease, and the gap between animal models and clinical reality.

Therapeutic Implications of Ferroptosis in Renal Fibrosis

Renal fibrosis is a common feature of chronic kidney disease (CKD), and can lead to the destruction of normal renal structure and loss of kidney function. Little progress has been made in reversing fibrosis in recent years. Ferroptosis is more immunogenic than apoptosis due to the release and activation of damage-related molecular patterns (DAMPs) signals. In this paper, the relationship between renal fibrosis and ferroptosis was reviewed from the perspective of iron metabolism and lipid peroxidation, and some pharmaceuticals or chemicals associated with both ferroptosis and renal fibrosis were summarized. Other programmed cell death and ferroptosis in renal fibrosis were also firstly reviewed for comparison and further investigation.

Ginsenoside Rg3 Alleviates Aluminum Chloride-Induced Bone Impairment in Rats by Activating the TGF-β1/Smad Signaling Pathway

Aluminum (Al)-induced bone formation and metabolism disorder through inhibition of the TGF-β1/Smad signaling pathway is one of the important mechanisms of bone impairment. Ginsenoside Rg3 (Rg3), a specific biological effector molecule, can provide protection to bones. Previously, we demonstrated that Rg3 can reverse aluminum chloride (AlCl₃)-induced oxidative stress and metabolic disorder of bones; however, whether the TGF-β1/Smad signaling pathway is involved in it remains unclear. First, we found that Rg3 attenuated Al-induced bone impairment in vivo and in vitro by relieving structural damage to the femur, increasing MC3T3-E1 cell activity, differentiation, mineralization, inhibition of cell apoptosis, and upregulating the extracellular matrix (ECM) synthesis and the expression of TGF-β1/Smad signaling pathway key factors. Subsequently, in the signal pathway intervention experiment, the protective effect of Rg3 on bone impairment induced by Al was weakened; these results indicate that activating the TGF-β1/Smad signaling pathway is one of the mechanisms of Rg3-attenuated Al-induced bone impairment.

Exploring the Effect of Dapagliflozin on Alcoholic Kidney Injury and Renal Interstitial Fibrosis in Rats Based on TIMP-1/MMP-24 Pathway

Objective

To establish a rat model of alcoholic kidney injury and detect the expression of TIMP-1/MMP-24 in the kidneys of rats with alcoholic kidney injury at the molecular pathological level, so as to explore the mechanism of alcohol abuse leading to kidney injury and renal interstitial fibrosis as well as the alleviation of alcohol-induced kidney injury and inhibition of renal interstitial fibrosis by dapagliflozin.

Methods

48 male rats were randomly divided into 4 groups: control group, alcohol group, alcohol + dapagliflozin group, and alcohol + losartan group, each with 12 rats. Different drugs were administered by gavage for modeling and treatment. Six days later, the rats were sacrificed, blood was collected from the heart to separate the serum, and the blood creatinine (Scr) and urea nitrogen (BUN) contents were detected biochemically. After blood collection, the kidney tissue was taken and fixed in10% neutral formalin. The expression of renal tissue inflammatory factors (CRP, IL-6, and TNF-α) and renal fibrosis indexes (LN, HA, and TGF-β1) were detected; MMP-24 and TIMP-1 in the kidney tissue of rats in different treatment groups were detected, and Smad3 expression was also detected.

Results

After treatment, the general condition of the alcohol + dapagliflozin group and the alcohol + losartan group improved to different degrees. The weight first decreased and then gradually increased over time. There was no statistical difference in the weight change between the two groups; Compared with the control group, the Scr level, BUN content, renal index, inflammatory factors, and renal fibrosis indexes in the alcohol group were significantly increased (P < 0.05); after 6 weeks of treatment, in the alcohol + dapagliflozin group and alcohol + losartan group, Scr level, BUN content, kidney index, inflammatory factors, and renal fibrosis indexes were significantly decreased (P < 0.05); the expression of MMP-24 in the kidney tissue of the control group was upregulated, and the expression of TIMP-1 and Smad3 was downregulated; MMP-24 expression was downregulated, and TIMP-1 and Smad3 expression was significantly upregulated (P < 0.05) in the rats of the alcohol group. After dapagliflozin and losartan treatment, MMP-24 expression gradually increased and TIMP-1 and Smad3 expression gradually decreased (P < 0.05).

Conclusion

Long-term large-scale alcohol intake can cause kidney tissue damage and fibrotic lesions. The expression of fibrotic cytokines such as TIMP-1 and Smad3 will increase, and the expression of MMP-24 will be decreased. However, dapagliflozin and losartan have certain therapeutic effects on the abovementioned lesions. The mechanism may be downregulating TIMP-1 and Smad3 and upregulating the expression of MMP-24 and other cytokines in the kidney.

The First Thousand Days: Kidney Health and Beyond

The global burden of chronic kidney disease (CKD) is rising. A superior strategy to advance global kidney health is required to prevent and treat CKD early. Kidney development can be impacted during the first 1000 days of life by numerous factors, including malnutrition, maternal illness, exposure to chemicals, substance abuse, medication use, infection, and exogenous stress. In the current review, we summarize environmental risk factors reported thus far in clinical and experimental studies relating to the programming of kidney disease, and systematize the knowledge on common mechanisms underlying renal programming. The aim of this review is to discuss the primary and secondary prevention actions for enhancing kidney health from pregnancy to age 2. The final task is to address the potential interventions to target renal programming through updating animal studies. Together, we can enhance the future of global kidney health in the first 1000 days of life.

Renal ischemia-reperfusion leads to hypertension and changes in proximal tubule Na+ transport and renin-angiotensin-aldosterone system: Role of NADPH oxidase

Acute renal injury (AKI) is a risk factor for the development of hypertension, which involves oxidative stress, changes in Na⁺ handling, and the intrarenal renin-angiotensin-aldosterone system (RAAS) as underlying mechanisms. We investigated in rats whether renal ischemia-reperfusion (IR) leads to changes in the proximal tubule ATP-dependent Na⁺ transport and the intrarenal content of RAAS components, as well as the role of NADPH oxidase. Rats weighing 300-350 g were submitted to AKI by bilateral IR (n = 25). After IR injury, the animals were followed up for 4 weeks. One part (n = 7) received daily treatment with the NADPH oxidase inhibitor apocynin (100 mg/kg, drinking water), while another part (n = 9) received apocynin 24 h before and after IR. One group was submitted to sham surgery (n = 8). Four weeks after IR, the rats presented elevated systolic blood pressure, as well as increased lipid peroxidation, NADPH oxidase activity, (Na⁺+K⁺)ATPase activity, and upregulation of type 1 angiotensin II receptor in the renal cortex. On the other hand, there was a decrease in Na⁺-ATPase activity and downregulation of the isoforms 1 and 2 of the angiotensin-converting enzyme, type 2 angiotensin II receptor, and of the α and ε isoforms of protein kinase C. Most of these alterations was prevented by both apocynin treatment protocols. Thus, we conclude that AKI-induced by IR may induce changes in proximal tubule ATPases and RAAS components compatible with renal Na⁺ retention and hypertension. These data also indicate that the NADPH oxidase represents a key factor in the origin of these alterations.

Ochratoxin A induces epithelial-to-mesenchymal transition and renal fibrosis through TGF-β/Smad2/3 and Wnt1/β-catenin signaling pathways in vitro and in vivo

Ochratoxin A (OTA) is a toxin produced by fungi such as Aspergillus spp. and Penicillium spp. The key target organ of OTA toxicity is the kidney, and it is known that epithelial-to-mesenchymal transition (EMT) leading to fibrosis is enhanced after long-term exposure of the kidney to OTA. However, the mechanisms responsible for this onset are not precisely known. Therefore, the purpose of this study was to investigate the mechanism of OTA-induced EMT and fibrosis in human proximal tubule HK-2 cells and mouse kidneys. Cells were treated for 48 h with various concentrations of OTA (50, 100, and 200 nM) and mice underwent oral administration of various doses of OTA (200 and 1000 μg/kg body weight) for 12 weeks. Blood urea nitrogen and creatinine levels were increased in the serum of OTA-treated mice, and fibrosis was observed in kidney tissues. Furthermore, alpha-smooth muscle actin (α-SMA) and fibronectin levels were increased, and E-cadherin level was decreased by OTA in both HK-2 cells and kidney tissues. In addition, the expression levels of TGF-β, smad2/3, and β-catenin were increased after OTA treatment. α-SMA, E-cadherin, and fibronectin were shown to be regulated by the activation of transcription factors, smad2/3 and β-catenin. These results demonstrated that OTA induces EMT and renal fibrosis through Smad2/3 and β-catenin signaling pathways in vitro and in vivo.