A short treatment with resveratrol after a renal ischaemia-reperfusion injury prevents maladaptive repair and long-term chronic kidney disease in rats.

Acute kidney injury (AKI) often triggers physiological processes aimed at restoring renal function and architecture. However, this response can become maladaptive, leading to nephron loss and fibrosis. Although the therapeutic effects of resveratrol (RSV) are well established, its impact after AKI and for subsequent chronic kidney disease (CKD) remains unclear. This study assessed whether transient administration of RSV following ischaemia-reperfusion injury (IRI) could prevent the progression to CKD. Forty-one male Wistar rats were assigned randomly to sham surgery, bilateral renal ischaemia for 30 min (IR) or IR+RSV. The RSV treatment commenced 24 h after IRI and continued for 10 days. The rats were studied for either 10 days or 5 months, after which kidney function and structure were evaluated. Mitochondrial homeostasis, oxidant defence and renal inflammation state were also evaluated. Despite having the same severity of AKI, rats receiving RSV for 10 days after IRI exhibited significant improvement in kidney histological injury and reduced inflammation, although renal haemodynamic recovery was less pronounced. Resveratrol effectively prevented the elevation of tubular injury-related molecules and profibrotic signalling with reduced myofibroblast proliferation. Furthermore, RSV substantially improved the antioxidant response and mitochondrial homeostasis. After 5 months, RSV prevented the transition to CKD, as evidenced by the prevention of progressive proteinuria, renal dysfunction and tubulointerstitial fibrosis. This study demonstrates that a brief treatment with RSV following IRI is enough to prevent maladaptive repair and the development of CKD. Our findings highlight the importance of the early days of reperfusion, indicating that maladaptive responses can be reduced effectively following severe AKI. KEY POINTS: Physiological processes activated after acute kidney injury (AKI) can lead to maladaptive responses, causing nephron loss and fibrosis. Prophylactic renoprotection with resveratrol (RSV) has been described in experimental AKI, but its impact after AKI and for subsequent chronic kidney disease (CKD) remains unclear. In this study, we found that histological tubular injury persists 10 days after ischaemia-reperfusion injury and contributes to a failed repair phenotype in proximal tubular cells. Short-term RSV intervention influenced the post-ischaemic repair response and accelerated tubular recovery by reducing oxidative stress and mitochondrial damage. Furthermore, RSV targeted inflammation and profibrotic signalling during the maladaptive response, normalizing both processes. Resveratrol effectively prevented AKI-to-CKD transition even 5 months after the intervention. The study serves as a proof of concept, proposing RSV as a valuable candidate for further translational clinical studies to mitigate AKI-to-CKD transition.

Transient response of serpinA3 during cellular stress.

We demonstrated that serpinA3c/k relocates from the cytoplasm to the apical tubular membrane (ATM) in chronic kidney disease (CKD), suggesting its secretion in luminal space in pathophysiological contexts. Here, we studied serpinA3c/k expression and secretion under different stressful conditions in vitro and in vivo. HEK-293 cells were transfected with a FLAG-tagged serpinA3c/k clone and exposed to H2 O2 or starvation. Both stressors induced serpinA3c/k secretion but with a higher molecular weight. Glycanase treatment established that serpinA3c/k is glycosylated. Site-directed mutagenesis for each of the four glycosylation sites was performed. During cellular stress, serpinA3c/k secretion increased with each mutant except in the quadruple mutant. In rats and patients suffering acute kidney injury (AKI), an atypical urinary serpinA3c/k excretion (uSerpinA3c/k) was observed. In rats with AKI, the greater the induced kidney damage, the greater the uSerpinA3 c/k, together with relocation toward ATM. Our findings show that: (1) serpinA3c/k is glycosylated and secreted, (2) serpinA3c/k secretion increases during cellular stress, (3) its appearance in urine reveals a pathophysiological state, and (4) urinary serpinA3 excretion could become a potential biomarker for AKI.

SerpinA3K Deficiency Reduces Oxidative Stress in Acute Kidney Injury.

We previously showed that SerpinA3K is present in urine from rats and humans with acute kidney injury (AKI) and chronic kidney disease (CKD). However, the specific role of SerpinA3K during renal pathophysiology is unknown. To begin to understand the role of SerpinA3K on AKI, SerpinA3K-deficient (KOSA3) mice were studied 24 h after inducing ischemia/reperfusion (I/R) and compared to wild type (WT) mice. Four groups were studied: WT+S, WT+IR, KOSA3+S, and KOSA3+IR. As expected, I/R increased serum creatinine and BUN, with a GFR reduction in both genotypes; however, renal dysfunction was ameliorated in the KOSA3+IR group. Interestingly, the increase in UH2O2 induced by I/R was not equally seen in the KOSA3+IR group, an effect that was associated with the preservation of antioxidant enzymes' mRNA levels. Additionally, FOXO3 expression was initially greater in the KOSA3 than in the WT group. Moreover, the increase in BAX protein level and the decrease in Hif1a and Vegfa induced by I/R were not observed in the KOSA3+IR group, suggesting that these animals have better cellular responses to hypoxic injury. Our findings suggest that SerpinA3K is involved in the renal oxidant response, HIF1α/VEGF pathway, and cell apoptosis.

Urinary serpin-A3 is an early predictor of clinical response to therapy in patients with proliferative lupus nephritis.

We have previously reported that urinary excretion of serpin-A3 (uSerpA3) is significantly elevated in patients with active lupus nephritis (LN). Here, we evaluated the course of uSerpA3 during the first year of treatment and its association with response to therapy in patients with proliferative LN. The observational longitudinal study included 60 Mexican adults with proliferative LN followed during the first year after LN flare. uSerpA3 was detected by Western blot analysis at flare and after 3, 6, and 12 mo. The response to therapy was determined 1 yr after the LN flare. We evaluated the correlation between uSerpA3 and histological parameters at LN flare. The temporal association between uSerpA3 and response to therapy was analyzed with linear mixed models. uSerpA3 prognostic performance for response was evaluated with receiver-operating characteristic curves. Among the 60 patients studied, 21 patients (35%) were class III and 39 patients (65%) were class IV. uSerpA3 was higher in class IV than in class III LN (6.98 vs. 2.89 dots per in./mg creatinine, P = 0.01). Furthermore, uSerpA3 correlated with the histological activity index (r = 0.29, P = 0.02). There was a significant association between the temporal course of uSerpA3 and response to therapy. Responders showed a significant drop in uSerpA3 at 6 mo compared with LN flare (P < 0.001), whereas nonresponders persisted with elevated uSerpA3. Moreover, uSerpA3 was significantly lower at flare in responders compared with nonresponders (2.69 vs. 6.98 dots per in./mg creatinine, P < 0.05). Furthermore, uSerpA3 was able to identify nonresponders since 3 mo after LN flare (area under the curve: 0.77). In conclusion, uSerpA3 is an early indicator of kidney inflammation and predictor of the clinical response to therapy in patients with proliferative LN.NEW & NOTEWORTHY LN requires aggressive immunosuppression to improve long-term outcomes. Current indicators of remission take several months to normalize, prolonging treatment regiments in some cases. Serpin-A3 is present in urine of patients with proliferative LN. We evaluated the excretion of serpin-A3 in serial samples of patients with proliferative LN during the first year after flare. We found that uSerpA3 correlates with kidney inflammation and its decline at early points predicts the response to therapy 1 yr after flare.

Repeated Episodes of Ischemia/Reperfusion Induce Heme-Oxygenase-1 (HO-1) and Anti-Inflammatory Responses and Protects against Chronic Kidney Disease.

Preconditioning episodes of ischemia/reperfusion (IR) induce protection against acute kidney injury (AKI), however their long-term effect still unknown. We evaluated AKI to chronic kidney disease (CKD) transition, after three-mild or three-severe episodes of IR. AKI was induced by single bilateral IR (1IR), or three episodes of IR separated by 10-day intervals (3IR) of mild (20 min) or severe (45 min) ischemia. Sham-operated rats served as controls. During 9-months, the 1IR group (20 or 45 min) developed CKD evidenced by progressive proteinuria and renal fibrosis. In contrast, the long-term adverse effects of AKI were markedly ameliorated in the 3IR group. The acute response in 3IR, contrasted with the 1IR group, that was characterized by an increment in heme oxygenase-1 (HO-1) and an anti-inflammatory response mediated by a NFkB-p65 phosphorylation and IL-6 decrease, together with an increase in TGF-ß, and IL-10 expression, as well as in M2-macrophages. In addition, three episodes of IR downregulated endoplasmic reticulum (ER) stress markers expression, CHOP and BiP. Thus, repeated episodes of IR with 10-day intervals induced long-term renal protection accompanied with HO-1 overexpression and M2-macrophages increase.

Sirtuin 7 Deficiency Reduces Inflammation and Tubular Damage Induced by an Episode of Acute Kidney Injury.

Acute kidney injury (AKI) is a public health problem worldwide. Sirtuins are a family of seven NAD+-dependent deacylases, Overexpression of Sirtuin 1, 3, and 5 protect against AKI. However, the role of Sirtuin 7 (Sirt7) in AKI is not known. Here, we analyzed how Sirt7 deficient mice (KO-Sirt7) were affected by AKI. As expected, wild-type and Sirt7 heterozygotes mice that underwent renal ischemia/reperfusion (IR) exhibited the characteristic hallmarks of AKI: renal dysfunction, tubular damage, albuminuria, increased oxidative stress, and renal inflammation. In contrast, the KO-Sirt7+IR mice were protected from AKI, exhibiting lesser albuminuria and reduction in urinary biomarkers of tubular damage, despite similar renal dysfunction. The renoprotection in the Sirt7-KO+IR group was associated with reduced kidney weight, minor expression of inflammatory cytokines and less renal infiltration of inflammatory cells. This anti-inflammatory effect was related to diminished p65 expression and in its active phosphorylation, as well as by a reduction in p65 nuclear translocation. Sirt7 deficient mice are protected from AKI, suggesting that this histone deacetylase promotes tubular damage and renal inflammation. Therefore, our findings indicate that Sirt7 inhibitors may be an attractive therapeutic target to reduce NFκB signaling.

Serpin-A3 is Associated with Persistent Albuminuria in Adolescents with Secondary Podocytopathy, in a Region with High Prevalence of Chronic Kidney Disease of Unknown Origin.

Background: The state of Aguascalientes, Mexico, has been recognized as a chronic kidney disease hotspot. Screening studies have revealed a high prevalence of persistent albuminuria (pA), histologically characterized by glomerulomegaly, and incomplete podocyte fusion, probably associated with oligonephrony. To date, urinary biomarkers have not been explored in this population. Objective: The aim of the study was to identify the presence of potential biomarkers of early renal injury in patients with pA (pACR) and that correspond with the characteristic nephropathy profile that prevails in this entity. Methods: This is a cross-sectional, analytical, and comparative study. Four groups were recruited: adolescents aged 10-17 years with pACR, isolated albuminuria (iACR), no albuminuria (negative control), and adults with biopsy-confirmed glomerulopathy (positive control). Urinary excretion of SerpinA3, heat-shock protein-72 (HSP-72), podocalyxin (PCX), and nephrin was evaluated in urine samples. SerpinA3 and HSP-72 were analyzed by Western blot, and PCX and nephrin were quantified by enzyme-linked immunosorbent assay. Results: The mean GFR in the pACR group was 113.4 mL/min/1.73m2 and differed significantly only from that of the positive control group (65.1 mL/min/1.73m2). The mean albuminuria value in the pACR group was 48.9 mg/g. SerpinA3 concentration differed between groups (0.08 vs. 0.25 ng/mL, p < 0.001): it was significantly higher in the pACR group compared to the negative controls (p = 0.037). Conclusion: SerpinA3 was significantly associated with pA and could become a biomarker of early kidney injury. Further investigations are required to determine whether SerpinA3 precedes the development of albuminuria and its pathogenic role.

Factors Associated with Development of Acute Kidney Injury After Liver Transplantation.

BACKGROUND: Early post-liver transplant (LT) acute kidney injury (AKI) has been associated with worse short-term and long-term outcomes, but the incidence and risk factors in our population are unknown. METHODS: We designed a prospective, singlecenter, longitudinal cohort study to determine the incidence of AKI during the immediate postoperative period of LT, and to identify the risk factors associated with AKI after LT. Pre-operative and intraoperative variables were analyzed to determine if there was any correlation with the development of post-operative AKI. RESULTS: Eighty-six patients were included in the final analysis; from them, 45 (52%) developed AKI in the following 30 days after LT. The presence of hepatic encephalopathy prior to LT was the factor most strongly associated with the development of AKI (Relative Risk 3.67, 95% Confidence Interval 1.08-8.95). Other factors associated with AKI development were male gender and a higher serum lactate during surgery. CONCLUSION: AKI was a frequent complication that significantly worsened the prognosis of LT recipients and was associated with an increased 30-day mortality rate. The presence of hepatic encephalopathy strongly predicted the development of severe AKI.

Reduced endothelial nitric oxide synthase activation contributes to cardiovascular injury during chronic kidney disease progression.

Major cardiovascular events are a common complication in patients with chronic kidney disease (CKD). Endothelial dysfunction can contribute to the cardiovascular injury observed in CKD. Here, we used a rat model of acute kidney injury to CKD transition to investigate heart alterations in the pathway activating endothelial nitric oxide synthase (eNOS) and its impact on the cardiac injury observed during CKD progression. Fifty male Wistar rats were subjected to sham surgery (n = 25) or bilateral renal ischemia-reperfusion (IR-CKD) for 45 min (n = 25). Rats were studied on a monthly basis up to 5 mo (n = 5). In another set of sham and IR-CKD rats, l-arginine was administered starting on the third month after renal ischemia. CKD development and cardiac alterations were monitored in all groups. CKD was characterized by a progressive increase in proteinuria and renal dysfunction that was evident after the fifth month of followup. Heart hypertrophy was observed starting on the fourth month after ischemia-reperfusion. There was a significant increase in brain natriuretic peptide levels. In the heart, IR-CKD rats had increased eNOS phosphorylation at threonine 495 and reduced eNOS-heat shock protein-90α interactions. l-Arginine administration prevented the heart alterations observed during CKD and increased eNOS coupling/dimerization and activation. In summary, CKD progression is accompanied by cardiac hypertrophy, fibrosis, oxidative stress, and increased brain natriuretic peptide levels. These alterations were associated with limited eNOS activation in the heart, which may result in reduced nitric oxide bioavailability and contribute to cardiac injury during CKD.

Resilience to acute kidney injury in offspring of maternal protein restriction.

Protein restriction (PR) during pregnancy induces morphofunctional alterations related to deficient nephrogenesis. We studied the renal functional and morphological significance of PR during pregnancy and/or lactation in adult male rat offspring and the repercussions on acute kidney injury (AKI) severity. Female rats were randomly assigned to the following groups: control diet during pregnancy and lactation (CC), control diet during pregnancy and PR diet during lactation (CR), PR during pregnancy and control diet during lactation (RC), and PR during pregnancy and lactation (RR). Three months after birth, at least 12 male offspring of each group randomly underwent either bilateral renal ischemia for 45 min [ischemia-reperfusion (IR)] or sham surgery. Thus, eight groups were studied 24 h after reperfusion: CC, CC + IR, CR, CR + IR, RC, RC + IR, RR, and RR + IR. Under basal conditions, the CR, RC, and RR groups exhibited a significant reduction in nephron number that was associated with a reduction in renal blood flow. Glomerular hyperfiltration was present as a compensatory mechanism to maintain normal renal function. mRNA levels of several vasoactive, antioxidant, and anti-inflammatory molecules were decreased. After IR, renal function was similarly reduced in all of the studied groups. Although all of the offspring from maternal PR exhibited renal injury, the magnitude was lower in the RC and RR groups, which were associated with faster renal blood flow recovery, differential vasoactive factors, and hypoxia-inducible factor-1α signaling. Our results show that the offspring from maternal PR are resilient to AKI induced by IR that was associated with reduced tubular injury and a differential hemodynamic response.

Spironolactone reduces oxidative stress in living donor kidney transplantation: a randomized controlled trial.

Mineralocorticoid receptor antagonism prevents acute kidney injury induced by ischemia-reperfusion in rodent and pig preclinical models. In a pilot study, we showed that spironolactone (25 mg) reduced oxidative stress after 5 days of kidney transplant (KT). In the present study, we investigated the effects of higher doses (50 and 100 mg) of spironolactone on kidney function, tubular injury markers, and oxidative stress in living donor KT recipients. We included KT recipients aged 18 yr or older who received immunosuppression therapy with IL-2 receptor antagonist, mycophenolate mofetil, corticosteroids, and tacrolimus with negative cross-match, and compatible blood group. Patients were randomized to receive placebo (n = 27), spironolactone (50 mg, n = 25), or spironolactone (100 mg, n = 25). Treatment was given from 3 days before and up to 5 days after KT. Serum creatinine, K+, urine neutrophil gelatinase-associated lipocalin-2, heat shock protein 72, and 8-hydroxy-2-deoxyguanosine levels were assessed. As expected, kidney function was improved after KT. Serum K+ remained in the normal range along the study. There was no significant effect of spironolactone on urinary neutrophil gelatinase-associated lipocalin-2 levels, whereas the increase in urinary heat shock protein 72 levels tended to be less intense in the 100 mg spironolactone-treated group (P = 0.054). In the placebo-treated group, urinary 8-hydroxylated-guanosine levels increased on days 3 and 5 after transplantation. This effect was prevented in patients that received spironolactone. In conclusion, spironolactone reduces the acute increase in urinary oxidative stress in living donor KT recipients.

Delayed spironolactone administration prevents the transition from acute kidney injury to chronic kidney disease through improving renal inflammation.

BACKGROUND: Acute kidney injury (AKI) is not as harmless as previously thought since it may lead to chronic kidney disease (CKD). Because most of the time ischemic AKI occurs unexpectedly, it is difficult to prevent its occurrence and there are no specific therapeutic approaches to prevent the AKI to CKD transition. We aimed to determine whether mineralocorticoid receptor blockade (MRB) in the first days after ischemia/reperfusion (IR) can prevent progression to CKD. METHODS: Four groups of male Wistar rats were included: sham and three groups of bilateral renal ischemia for 45 min, one without treatment and the other two receiving spironolactone for 5 or 10 days, starting 24 h after IR. The rats were studied at 10 days or 5 months after ischemia induction. RESULTS: After 5 months of follow-up, the untreated group exhibited clear evidence of AKI to CKD progression, such as proteinuria, reduced renal blood flow, tubulointerstitial fibrosis, glomerulosclerosis and glomerular hypertrophy. All these alterations were prevented by both spironolactone treatments initiated 24 h after IR, the 10-day treatment being more effective. Within the early mechanisms of the MRB protective effect are the reduction of inflammation and increased endothelin-B-receptor expression and endothelial nitric oxide synthase activation in the first 10 days after IR. CONCLUSIONS: We propose that MRB, administered 24 h after the ischemic injury that leads to AKI, reduces inflammation and promotes efficient tissue repair that avoids the AKI to CKD transition. These data highlight a therapeutic window to preclude CKD development after AKI.

Pirfenidone prevents acute kidney injury in the rat.

BACKGROUND: Pirfenidone is an orally active drug used for the treatment of idiopathic pulmonary fibrosis to slow loss of lung function; it acts mainly through an antifibrotic effect but also possesses antioxidant and anti-inflammatory properties. We assessed the effect of prophylactic administration of pirfenidone on acute kidney injury due to bilateral renal ischemia. METHODS: Eighteen rats were included and divided in: 1) sham-operated rats (S), 2) rats underwent bilateral renal ischemia for 20 min (I/R), and 3) rats treated with pirfenidone 700 mg/kg/day 24 h before surgery and subjected to bilateral renal ischemia for 20 min (I/R + PFN). All the rats were euthanized and studied 24 h after renal reperfusion. RESULTS: As was expected, the I/R group exhibited a significant reduction in creatinine clearance, urinary output and renal blood flow, as well as extensive tubular injury. These alterations were associated with a significant decrease in urinary excretion of nitrites and nitrates (UNO2/NO3V). In the I/R + PFN group, recovery of renal function and UNO2/NO3V was observed, together with lesser histological signs of tubular injury compared to the I/R group. CONCLUSIONS: This study shows that prophylactic administration of pirfenidone prevented acute kidney injury due to bilateral ischemia in the rat. Recovery of NO production appears to be one of the mechanism of pirfenidone renoprotective effect. Our findings suggest that pirfenidone is a promising drug to reduce renal injury induced by I/R.

HSP72 is an early biomarker to detect cisplatin and acetaminophen nephrotoxicity.

OBJECTIVE: To evaluate whether the urinary HSP72 levels (uHSP72) are a useful biomarker for early diagnosis of acute kidney injury (AKI) induced by two widely used drugs: cisplatin and acetaminophen. MATERIALS AND METHODS: To analyze the time-course of nephrotoxic injury and uHSP72 levels, male Wistar rats were administered a single high dose of cisplatin (7 mg/kg) or acetaminophen (750 mg/kg) and were assessed at 6, 12, 24, 48, 72, 96 and 120 h. RESULTS: AKI induced by cisplatin was characterized by tubular injury that started at 6 h and was enhanced after 48 h. Plasma creatinine was increased only after 72 h. In contrast, uHSP72 levels were augmented after 6 h and were enhanced after 48 h of cisplatin administration, which was consistent with the tubular injury. In acetaminophen-induced AKI, the tubular lesions were less severe and predominantly characterized by tubular cell detachment. Interestingly, uHSP72 levels were increased after 6 h of acetaminophen injection and remained elevated at the following time points, reflecting the tubular injury, even in the absence of major functional changes. CONCLUSIONS: In two models of renal injury induced by nephrotoxic drugs, we showed that uHSP72 could be used as an early biomarker to detect subtle to severe tubular injury.

AT1 receptor antagonism before ischemia prevents the transition of acute kidney injury to chronic kidney disease.

Despite clinical recovery of patients from an episode of acute kidney injury (AKI), progression to chronic kidney disease (CKD) is possible on long-term follow-up. However, mechanisms of this are poorly understood. Here, we determine whether activation of angiotensin-II type 1 receptors during AKI triggers maladaptive mechanisms that lead to CKD. Nine months after AKI, male Wistar rats develop CKD characterized by renal dysfunction, proteinuria, renal hypertrophy, glomerulosclerosis, tubular atrophy, and tubulointerstitial fibrosis. Renal injury was associated with increased oxidative stress, inflammation, α-smooth muscle actin expression, and activation of transforming growth factor ß; the latter mainly found in epithelial cells. Although administration of losartan prior to the initial ischemic insult did not prevent or reduce AKI severity, it effectively prevented eventual CKD. Three days after AKI, renal dysfunction, tubular structural injury, and elevation of urinary biomarkers were present. While the losartan group had similar early renal injury, renal perfusion was completely restored as early as day 3 postischemia. Further, there was increased vascular endothelial growth factor expression and an early activation of hypoxia-inducible factor 1 α, a transcription factor that regulates expression of many genes that help reduce renal injury. Thus, AT1 receptor antagonism prior to ischemia prevented AKI to CKD transition by improving early renal blood flow recovery, lesser inflammation, and increased hypoxia-inducible factor 1 α activity.

Heat shock protein 72 (Hsp72) specific induction and temporal stability in urine samples as a reliable biomarker of acute kidney injury (AKI).

We demonstrated that urinary heat shock protein of 72 KDa (Hsp72) is a sensitive biomarker for the early detection of acute kidney injury (AKI). However, whether Hsp72 induction during an AKI episode is kidney-specific is unknown, as well as, the degree of Hsp72 stability in urine samples. In rats that underwent bilateral renal ischemia and reperfusion (I/R), Hsp72 levels were evaluated in several tissues and in collected urines under different storage and temperature conditions, as well as in variable numbers of freeze-thaw cycles. The effect of room temperature and five freeze-thaw cycles on urinary Hsp72 levels was also evaluated in urine samples from AKI patients. We found that Hsp72 increased exclusively in the renal cortex of I/R group, emphasizing its performance as an AKI biomarker. Urinary-Hsp72 remained constant at room temperature (48 h), during 9 months of storage and was not affected by five freeze/thaw cycles.

Intra-renal transfection of heat shock protein 90 alpha or beta (Hsp90α or Hsp90ß) protects against ischemia/reperfusion injury.

BACKGROUND: We previously reported that radicicol (Hsp90 inhibitor) induced a reduction in the renal blood flow and glomerular filtration rate, in part due to a reduction in urinary NO2/NO3 excretion, suggesting that Hsp90 regulates renal vascular tone in physiological conditions. However, there is a lack of information concerning Hsp90α or Hsp90ß role on eNOS activity and their association with acute kidney injury (AKI) characterized by an inadequate NO production. This study evaluated the effects of Hsp90α or Hsp90ß intra-renal transfection under ischemia/reperfusion (IR) injury. METHODS: Uninephrectomized (Nx) rats were intra-renally transfected through injections with Hsp90α or Hsp90ß cloned into pcDNA3.1(+) or empty vector (EV) at 48 h before inducing IR, as indicated in the following groups: (i) Nx+sham, (ii) Nx+IR, (iii) Nx+IR+EV, (iv) Nx+IR+Hsp90α and (v) Nx+IR+Hsp90ß. After 24 h, physiological, histopathological, biochemical and molecular studies were performed. RESULTS: IR-induced renal dysfunction, structural injury, tubular proliferation, the elevation of urinary Hsp72 and the reduction of urinary NO2/NO3 excretion. These alterations were associated with reduced eNOS-Hsp90 coupling and changes in the eNOS phosphorylation state mediated through a reduction in PKCα and increased Rho kinase expression. In contrast, intra-renal transfection of Hsp90α or Hsp90ß prevented IR injury that was associated with the restoration of eNOS-Hsp90 coupling, eNOS activating phosphorylation and PKCα and Rho kinase levels. CONCLUSIONS: Here we showed that eNOS-Hsp90 uncoupling plays a critical role in promoting NO reduction during IR. This effect was effectively reversed through Hsp90α or Hsp90ß intra-renal transfection, suggesting their implication in regulating NO/eNOS pathway and the renal vascular tone.

Transient inhibition of sodium-glucose cotransporter 2 after ischemia/reperfusion injury ameliorates chronic kidney disease.

Sodium-glucose cotransporter 2 (SGLT2) inhibitor, dapagliflozin (Dapa), exhibited nephroprotective effects in patients with chronic kidney disease (CKD). We assessed the efficacy of short-term Dapa administration following acute kidney injury (AKI) in preventing CKD. Male Wistar rats were randomly assigned to Sham surgery, bilateral ischemia for 30 minutes (abbreviated as IR), and IR + Dapa groups. Daily treatment with Dapa was initiated just 24 hours after IR and maintained for only 10 days. Initially, rats were euthanized at this point to study early renal repair. After severe AKI, Dapa promptly restored creatinine clearance (CrCl) and significantly reduced renal vascular resistance compared with the IR group. Furthermore, Dapa effectively reversed the mitochondrial abnormalities, including increased fission, altered mitophagy, metabolic dysfunction, and proapoptotic signaling. To study this earlier, another set of rats was studied just 5 days after AKI. Despite persistent renal dysfunction, our data reveal a degree of mitochondrial protection. Remarkably, a 10-day treatment with Dapa demonstrated effectiveness in preventing CKD transition in an independent cohort monitored for 5 months after AKI. This was evidenced by improvements in proteinuria, CrCl, glomerulosclerosis, and fibrosis. Our findings underscore the potential of Dapa in preventing maladaptive repair following AKI, emphasizing the crucial role of early intervention in mitigating AKI long-term consequences.

Spironolactone prevents chronic kidney disease caused by ischemic acute kidney injury.

Acute kidney injury (AKI) has been recognized as a risk factor for the development of chronic kidney disease (CKD). Aldosterone has a critical role in promoting renal injury induced by ischemia. Here, we evaluated whether spironolactone administered before or after AKI caused by ischemia protects against CKD. In the first set of experiments, Wistar rats underwent a sham operation without or with prior spironolactone treatment, or underwent 45 minutes of bilateral renal ischemia without or with spironolactone treatment before ischemia and assessed over 270 days. The second set of rats received low (20 mg/kg) or high (80 mg/kg) doses of spironolactone at three different times after the sham operation or bilateral renal ischemia and were assessed after 90 days. Untreated animals developed CKD following ischemia-induced AKI as characterized by a progressive increase in proteinuria, renal dysfunction, podocyte injury, glomerular hypertrophy, and focal sclerosis. This was associated with increased oxidative stress, an upregulation of tumor growth factor (TGF)-ß, followed by upregulation of the TGF-ß downstream effectors phospho-Smad3, collagen I, fibronectin, and proinflammatory cytokines. Treatment with spironolactone either before or after ischemia prevented subsequent CKD by avoiding the activation of fibrotic and inflammatory pathways. Thus, spironolactone may be a promising treatment for the prevention of AKI-induced CKD.

Mineralocorticoid receptor blockade reduced oxidative stress in renal transplant recipients: a double-blind, randomized pilot study.

BACKGROUND: Previous experimental studies from our laboratory have demonstrated that aldosterone plays a central role in renal ischemic processes. This study was designed to evaluate the effect of mineralocorticoid receptor blockade in renal transplant recipients from living donors. METHODS: 20 adult kidney transplant recipients from living donors were included in a double-blind, randomized, placebo-controlled clinical pilot study that compared spironolactone and placebo. Placebo or spironolactone (25 mg) was administered 1 day before and 3 days posttransplantation. Renal function and urinary kidney injury molecule-1, interleukin-18, and heat shock protein 72 as well as urinary hydrogen peroxide (H2O2) levels were quantified. RESULTS: No significant differences were seen between the groups studied regarding age, gender, indication for kidney transplantation, residual renal function, renal replacement therapy, or warm and cold ischemia periods. In contrast, spironolactone administration significantly reduced the oxidative stress assessed by the urinary H2O2 excretion, in spite of no differences in renal function or reduction in tubular injury biomarkers. CONCLUSIONS: The findings of this exploratory study strongly suggest that aldosterone promotes oxidative stress and that the administration of spironolactone reduces the production of urinary H2O2 as a result of lesser formation of surrogate reactive oxygen species secondary to the ischemia-reperfusion phenomenon.