Eduardo Homsi

Prophylaxis of Acute Renal Failure in Patients with Rhabdomyolysis

Patients that develop rhabdomyolysis of different causes are at high risk of acute renal failure. Efforts to minimize this risk include volume repletion, treatment with mannitol, and urinary alkalinization as soon as possible after muscle injury. This is a retrospective analysis (from January 1, 1992, to December 31, 1995) of therapeutic response to prophylactic treatment in patients with rhabdomyolysis admitted to an intensive care unit (ICU). The diagnosis of rhabdomyolysis was based on creatinine kinase (CK) level (> 500 Ui/L) and the criteria for prophylaxis were: time elapsed between muscle injury to ICU admission < 48 h and serum creatinine < 3 mg/dL. Fifteen patients were treated with the association of saline, mannitol, and sodium bicarbonate (S + M + B group) and 9 patients received only saline (S group). Serum creatinine at admission was similar in both groups: 1.6 +/- 0.6 mg/dL in the S + M + B group and 1.5 +/- 0.6 mg/dL in the S group (p > 0.05). Maximum serum CK measured was 3351 +/- 1693 IU/L in the S + M + B group and 1747 +/- 2345 IU/L in the S group (p < 0.05). However the measurement of CK was earlier in S + M + B patients (1.7 vs 2.7 days after rhabdomyolysis). APACHE II scores were 16.9 +/- 7.4 and 13.4 +/- 4.9 in the S + M + MB and S groups, respectively (p > 0.05). Despite the treatment protocol the serum levels of creatinine had similar behavior and reached normal levels in all patients in 2 or 3 days. The saline infusion during the first 60 h on the ICU was 206 mL/h in the S group and 204 mL/h in S + M + B (p > 0.05). Mannitol dose was 56 g/day, and bicarbonate 225 mEq/day during 4.7 days. Our data show that progression to established renal failure can be totally avoided with prophylactic treatment, and that once appropriate saline expansion is provided, the association of mannitol and bicarbonate seems to be unnecessary.

Interleukin-6 Stimulates Tubular Regeneration in Rats with Glycerol-Induced Acute Renal Failure

Interleukin-6 stimulates tubular regeneration in rats with glycerol-induced acute renal failure. Background: Interleukin 6 (IL-6) is a pleiotropic cytokine released after endotoxemia, trauma and organ injury. IL-6 may act in cellular proliferation activating transduction signals and Ras/Map cascade or the HGF/c-met axis. We tested the effect of IL-6 in the regeneration of tubular epithelia after acute tubular necrosis (ATN) in rats. Methods: Rats with glycerol-induced acute renal failure (Gly-ARF) were treated with IL-6 200 µg/kg/day. Functional, histological and immunohistochemical tests were done 24 and 72 h after Gly-ARF to localise mitotic cells (BrdU). The renal expression of c-met (Western-Blot) and circulating levels of HGF (ELISA) were also determined. Results: Rats with Gly-ARF had reduced creatinine clearance that was not influenced by IL-6. The histological appearance of ATN was also unaffected by IL-6. The IL-6 treated rats showed a significant increase in tubular cell proliferation in cortex and medulla, as well as in the expression of c-met protein in the renal cortex, compared to untreated Gly-ARF rats. The plasma HGF concentration was equally elevated in treated and untreated Gly-ARF rats. Discussion: IL-6 stimulates tubular regeneration after Gly-ARF and increases the expression of c-met in the renal cortex. Gly-ARF rats have high circulating levels of HGF that is targeted to act in the injured kidneys by the IL-6 overexpressed renal c-met.

Endogenous Hepatocyte Growth Factor Attenuates Inflammatory Response in Glycerol-Induced Acute Kidney Injury

Background: Hepatocyte growth factor (HGF) is overexpressed after acute kidney injury (AKI). The aim of this study was to evaluate the role of endogenous HGF in the progression of the inflammatory response in glycerol-induced AKI (Gly-AKI) in rats. Methods: Renal and systemic HGF expressions were evaluated during the development of Gly-AKI. Subsequently, the blockade of endogenous HGF was analyzed in rats treated with anti-HGF antibody concomitant to glycerol injection. Apoptosis, cell infiltration and chemokine and cytokine profiles were investigated. Results: We detected an early peak of renal and plasma HGF protein expressions 3 h after glycerol injection. The pharmacological blockade of the endogenous HGF exacerbated the renal impairment, the tubular apoptosis, the renal expression of monocyte chemoattractant protein-1 and the macrophage, CD43+, CD4+ and CD8+ T lymphocytes renal infiltration. The analysis of mRNA expressions of Th1 (t-bet, TNF-α, IL-1β) and Th2 (gata-3, IL-4, IL-10) cytokines showed a Th1-polarized response in Gly-AKI rats that was aggravated with the anti-HGF treatment. Conclusion: Endogenous HGF attenuates the renal inflammatory response, leukocyte infiltration and Th1 polarization after glycerol injection. The control of cellular immune response may partly explain the protective effect of endogenous HGF in the development of Gly-AKI.

TNF-α-mediated cardiorenal injury after rhabdomyolysis in rats.

The TNF-α serum level increases after rhabdomyolysis and is involved in the subsequent cardiorenal injury. In the present study, we investigated the TNF-α-dependent cell signaling pathways implicated in cellular injury in these organs. Rhabdomyolysis was induced by intramuscular glycerol injection in rats. Renal function, cardiac and renal pathology, and activation of caspases were evaluated during the first 24 h after glycerol injection. TNF-α blockade with infliximab reduced tubular necrosis and cardiorenal apoptosis. Cellular Fas-associated protein with death domain-like IL-1β-converting enzyme inhibitory protein (cFLIP), an inhibitor of caspase-8, was overexpressed in the kidney but not in the heart. The inhibitory effect of cFLIP blunted caspase-8 activation in the kidney. In this condition, the cellular response to the TNF-α stimulus was driven to receptor-interacting protein-1 (RIP1)-mediated necroptosis. Treatment with RIP1 inhibitor (necrostatin-1) isolated or in combination with infliximab showed a similar reduction in tubular necrosis, underscoring the importance of TNF-α-mediated tubular necroptosis in this model. TNF-α played a positive regulatory role in the transcription of proapoptotic Bax and p53-upregulated modulator of apoptosis (PUMA) proteins. Infliximab treatment reduced caspase-9-mediated apoptosis in both organs. Treatment with a caspase-8 inhibitor showed that caspase-8 participated in the process of apoptosis only in the heart, upstream of caspase-9 activation. TNF-α-mediated necroptosis is the predominant form of tubular injury observed in the glycerol model. TNF-α up regulates Bax and PUMA proapoptotic proteins, resulting in activation of the intrinsic pathway of apoptosis in the kidney and heart.

Effects of melatonin administration to rats with glycerol-induced acute renal failure

Melatonin, the pineal hormone with antioxidative properties was administered to rats with glycerol-induced myoglobinuric acute renal failure (Gly-ARF). This model is characterized by acute tubular necrosis mediated by heme-iron oxidative stress. Rats received melatonin (20 mg/kg) concomitant and 3 h after glycerol injection. Gly-ARF rats showed at 24 h a 78% reduction in glomerular filtration rate, whereas this decrement was significantly reduced to 35% in the melatonin treated Gly-ARF rats. Tubular function evaluated by tubular reabsorption of sodium and lithium was also preserved in melatonin treated rats. The histologic analysis revealed extensive cortical tubular necrosis that was significantly reduced by melatonin treatment. The renal concentration of malondialdehyde (MDA) was increased 6 h after glycerol injection in Gly-ARF and this elevation was prevented when melatonin was administered. Renal concentration of reduced glutathione (GSH) was decreased at 6 h in Gly-ARF and melatonin did not reverse this decrease. It was concluded that melatonin administration attenuated the renal injury in the glycerol model of acute renal failure and reduced kidney oxidative stress through a GSH-independent mechanism.

p53-Mediated oxidative stress and tubular injury in rats with glycerol-induced acute kidney injury.

Background/Aims: p53 is a transcriptional factor that responds to severe cell damage promoting the transcription of proapoptotic and prooxidant genes. In this study, we evaluated the role of p53 activation in glycerol-induced acute kidney injury (Gly-AKI). Methods: Rats were treated with p53 inhibitor (pifithrin-α) in the moment we injected glycerol. Renal function, renal histology (HE), TUNEL labeling, cleaved caspase-3 staining, renal p53, Bax, PUMA, Bcl-2, p21 and survivin expressions, renal lipid and DNA oxidative markers, and the expression of antioxidant enzymes (Mn-SOD, HO-1, and NAD(P)H:quinone-oxidoreductase-1) were evaluated. Results: Gly-AKI rats showed an increased renal expression of phosphorylated-p53. The p53 inhibitor attenuated renal impairment and significantly reduced tubular injury. The expression of the oxidative markers was significantly reduced in treated rats. Proapoptotic and prooxidant proteins Bax and PUMA were overexpressed in Gly-AKI rats and reduced in treated rats. On the contrary, antiapoptotic Bcl-2, p21, and survivin showed a tendency to increase in treated rats. The antioxidant enzymes’ expression remained elevated or increased in treated rats. Conclusion: On the whole, p53 inhibition was protective in the short term. The oxidative stress subsided and the transcription tipped toward prosurvival genes; consequently tubular injury was attenuated in treated rats.

Silymarin exacerbates p53-mediated tubular apoptosis in glycerol-induced acute kidney injury in rats

Background/aims: Silymarin is an herbal extract with antioxidant properties that can reduce oxidative stress-mediated injuries in murine models of liver, heart, and kidney diseases. Silymarin can also increase p53-mediated cellular apoptosis in vitro. We tested the effect of silymarin administration before glycerol-induced acute kidney injury (Gly-AKI) in rats. Methods: Renal function, tubular injury, oxidative stress, leukocytes infiltration, and renal expression of apoptosis regulating proteins (p53, p-p53, Bax, Bcl-2, survivin, and cleaved caspase-3) were evaluated 6 or 24 h after glycerol. Results: Silymarin exacerbated the renal impairment and tubular apoptosis but had no effect on tubular necrosis or renal leukocytes infiltration. Renal lipid and DNA peroxidation was increased after glycerol and silymarin did not reduce oxidative stress. Proteins p53, p-p53, and proapoptotic Bax were upregulated in Gly-AKI rats treated with silymarin, whereas anti-apoptotic Bcl-2 was reduced in this group. Cleaved caspase-3 was overexpressed in Gly-AKI rats, particularly when treated with silymarin. Survivin was less expressed in Gly-AKI than in controls, but this deficit was not aggravated by silymarin. Conclusion: The persistence of oxidative stress, inflammatory reaction, and tubular necrosis, as well as exacerbation of p53-mediated tubular apoptosis, led to a more severe renal impairment in Gly-AKI rats treated with silymarin.

Effects of Nifedipine and Platelet Activating Factor Antagonist (BN 52021) in Glycerol-Induced Acute Renal Failure in Rats

We studied the actions of nifedipine and the platelet activating factor (PAF) antagonist BN 52021 on renal and tubular function in glycerol-induced acute renal failure (Gly-ARF). The tubular handling of sodium was evaluated through the lithium clearance method in awake rats in metabolic cages. The sequential analysis of tubular function 3, 6, 12, and 24 h after Gly-ARF showed a sharp decrease in fractional proximal Na reabsorption (FPRNa)--control 74.1 +/- 12.5%, 3 h: 79.5 +/- 6.0%; 6 h: 41.8 +/- 15.9%; 12 h: 22.9 +/- 17.9%; and 24 h: 31.1 +/- 16.2% (p < 0.001) while fractional distal Na reabsorption (FDRNa) did not change during the study. The effect of nifedipine (20 mg/kg p.o.) and BN 52021 (1 mg/kg i.p.) were evaluated 24 h after the induction of Gly-ARF. Both drugs attenuated the reduction in creatinine clearance (control 431.8 +/- 108.2, glycerol 96.7 +/- 43.8, glycerol plus nifedipine 264.9 +/- 103.5, and glycerol plus BN 52021 188.9 +/- 69.8 microL/min/100 g, p < 0.001). However, only nifedipine could keep FPRNa higher than untreated rats (58.3 +/- 13.2 vs. 31.1 +/- 16.2%, p < 0.05) and reduced the tubular necrosis on histologic semiquantitative analysis. Our data showed that nifedipine and BN 52021 could protect against filtration failure in Gly-ARF but that only nifedipine reduced the proximal tubular lesion.

Attenuation of Glycerol-Induced Acute Kidney Injury by Previous Partial Hepatectomy: Role of Hepatocyte Growth Factor/c-met Axis in Tubular Protection

Background/Aims: Previous partial hepatectomy (HPTX) can attenuate glycerol-induced acute kidney injury (Gly-AKI). The aim of this study was to explore the pathophysiological mechanisms and the role of hepatocyte growth factor (HGF) in kidney protection. Methods: Rats were subjected to HPTX 24 h before glycerol administration. Renal function, acute tubular necrosis, apoptosis, leukocyte infiltration, and the expression of HGF, c-met, monocyte chemoattractant protein-1, interleukin-1β, and heme oxygenase-1 were evaluated 24 h after glycerol injection. The regenerative response was analyzed from 6 to 72 h after glycerol injection (BrdU incorporation). In a separate series of experiments, Gly-AKI+HPTX rats were treated with anti-HGF antibody. Results: Gly-AKI+HPTX rats showed an increased expression of renal HGF and c-met as well as an improved creatinine clearance and reduced acute tubular necrosis and apoptosis, cytokine expression, and leukocyte infiltration. The regenerative response was less intense 24 and 72 h after glycerol administration in this group. The anti-HGF treatment disclosed an important role of HGF in the reduction of tubular injury, particularly apoptosis. Overexpression of heme oxygenase-1 was observed in Gly-AKI+HPTX rats, but was not associated with HPTX-induced renal protection. Conclusion: We conclude that Gly-AKI+HPTX rats have a reduced susceptibility to renal injury instead of an increased regenerative response and that endogenous HGF overexpression is responsible for suppression of tubular apoptosis.

Acute renal failure due to rhabdomyolysis in diabetic patients.

We report a 32-year-old Black man, admitted to the ICU with coma and severe metabolic disturbances due to diabetic ketoacidosis. During the admission, rhabdomyolysis and acute renal failure (ARF) were diagnosed. After metabolic control and gradual decrease of creatine kinase levels, he presented a progressive improvement of renal function. We emphasize nontraumatic rhabdomyolysis as a poorly recognized pathogenetic factor for ARF in diabetic ketoacidosis and suggest that a better understanding of its mechanisms and an early application of protective measures is necessary.