Metabolomics as an extension of proteomic analysis: study of acute kidney injury

Abstract

Although proteomics studies the global expression of proteins, metabolomics characterizes and quantifies their end products: the metabolites, produced by an organism under a certain set of conditions. From this perspective it is apparent that proteomics and metabolomics are complementary and when joined allow a fuller appreciation of an organism's phenotype. Our studies using (1)H-nuclear magnetic resonance spectroscopic analysis showed the presence of glucose, amino acids, and trichloroacetic acid cycle metabolites in the urine after 48 hours of cisplatin administration. These metabolic alterations precede changes in serum creatinine. Biochemical studies confirmed the presence of glucosuria, but also showed the accumulation of nonesterified fatty acids, and triglycerides in serum, urine, and kidney tissue, despite increased levels of plasma insulin. These metabolic alterations were ameliorated by the use of fibrates. We propose that the injury-induced metabolic profile may be used as a biomarker of cisplatin-induced nephrotoxicity. These studies serve to illustrate that metabolomic studies add insight into pathophysiology not provided by proteomic analysis alone.

Figure 1

Representative 1D ¹H NMR spectra of C) Control and following administration of cisplatin (D1) 24 hours (D2) 48 hours post-dosing (D3) 72 hours post-dosing.

Figure 2

PC scores plot showing the changes from control over a 72 hour period following administration of cisplatin (●) Control animals (Δ) 24 hours after dosing (■) 48 hours after dosing (+) 72 hours after dosing.

Figure 3

3D PCA scores plot of NMR data of day two urine indicating the effects of the PPARα ligand (WS) on cisplatin-induced ARF. (●) Control animals (■) Animals fed WY (Δ) Animals administered cisplatin following feeding with WY (+) Animals administered cisplatin.

Figure 4

Figure 4A. Effect of cisplatin on NEFA levels in serum, urine and kidney tissue. Mice were administered saline (control) or cisplatin (20 mg/kg body weight) by a single intraperitoneal injection. NEFA levels were measured at day1, day2, day3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods. Bars correspond to means ± SE of at least 6 independent experiments under each condition. *p < 0.05, compared with control by unpaired student’s t-test. Figure 4B Effect of cisplatin and fibrate (WY) on NEFA levels. Wild-type mice were fed with either a regular or WY-containing diet and then were given saline (control and WY groups) or cisplatin (cisplatin and cisplatin + WY groups). NEFA levels were measured at day 3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods Results are expressed as the means ± SE. †P < 0.05 compared to cisplatin, *P < 0.05, compared with control by unpaired Student’s t-test.

Figure 4

Figure 4A. Effect of cisplatin on NEFA levels in serum, urine and kidney tissue. Mice were administered saline (control) or cisplatin (20 mg/kg body weight) by a single intraperitoneal injection. NEFA levels were measured at day1, day2, day3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods. Bars correspond to means ± SE of at least 6 independent experiments under each condition. *p < 0.05, compared with control by unpaired student’s t-test. Figure 4B Effect of cisplatin and fibrate (WY) on NEFA levels. Wild-type mice were fed with either a regular or WY-containing diet and then were given saline (control and WY groups) or cisplatin (cisplatin and cisplatin + WY groups). NEFA levels were measured at day 3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods Results are expressed as the means ± SE. †P < 0.05 compared to cisplatin, *P < 0.05, compared with control by unpaired Student’s t-test.

Figure 5

Figure 5A. Effect of cisplatin on TG levels in serum, urine and kidney tissue. Mice were administered saline (control) or cisplatin (20 mg/kg body weight) by a single intraperitoneal injection. TG levels were measured in serum, urine and kidney tissues at day1, day2, day3 after cisplatin injection as described in Methods. Bars correspond to means ± SE of at least 6 independent experiments under each condition. **p < 0.005 compared with control by unpaired student’s t-test. Figure 5 B. Effect of cisplatin and fibrate (WY) on TG levels. Wild-type mice were fed with either a regular diet or WY-containing diet and then were given saline (control and WY groups) or cisplatin (cisplatin and cisplatin+WY groups). TG levels were measured in serum, and kidney tissue homogenates at day 3 after cisplatin injection as described in Methods. Results are expressed as the means ± SE. †P < 0.05 compared to cisplatin, *P < 0.05, **P < 0.005 compared with control by unpaired Student’s t-test.

Figure 5

Figure 5A. Effect of cisplatin on TG levels in serum, urine and kidney tissue. Mice were administered saline (control) or cisplatin (20 mg/kg body weight) by a single intraperitoneal injection. TG levels were measured in serum, urine and kidney tissues at day1, day2, day3 after cisplatin injection as described in Methods. Bars correspond to means ± SE of at least 6 independent experiments under each condition. **p < 0.005 compared with control by unpaired student’s t-test. Figure 5 B. Effect of cisplatin and fibrate (WY) on TG levels. Wild-type mice were fed with either a regular diet or WY-containing diet and then were given saline (control and WY groups) or cisplatin (cisplatin and cisplatin+WY groups). TG levels were measured in serum, and kidney tissue homogenates at day 3 after cisplatin injection as described in Methods. Results are expressed as the means ± SE. †P < 0.05 compared to cisplatin, *P < 0.05, **P < 0.005 compared with control by unpaired Student’s t-test.

Figure 6

Figure 6A. Effect of cisplatin on glucose levels in serum, urine, and kidney tissue. Mice were administered saline (control) or cisplatin (20 mg/kg body weight) by a single intraperitoneal injection. Glucose levels were measured at day1, day2, day3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods. Bars correspond to means ± SE of at least 6 independent experiments under each condition. *P < 0.05, **P < 0.005 compared with control by unpaired student’s t-test. Figure 6B. Effect of cisplatin and fibrate(WY) on glucose levels. Wild-type mice were fed with either a regular or WY-containing diet and then were given saline (control and WY groups) or cisplatin (cisplatin and cisplatin+WY groups). Glucose levels were measured at day 3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods Results are expressed as the means ± SE. †P < 0.05compared to cisplatin, *P < 0.05, **P < 0.005 compared with control by unpaired Student’s t-test.

Figure 6

Figure 6A. Effect of cisplatin on glucose levels in serum, urine, and kidney tissue. Mice were administered saline (control) or cisplatin (20 mg/kg body weight) by a single intraperitoneal injection. Glucose levels were measured at day1, day2, day3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods. Bars correspond to means ± SE of at least 6 independent experiments under each condition. *P < 0.05, **P < 0.005 compared with control by unpaired student’s t-test. Figure 6B. Effect of cisplatin and fibrate(WY) on glucose levels. Wild-type mice were fed with either a regular or WY-containing diet and then were given saline (control and WY groups) or cisplatin (cisplatin and cisplatin+WY groups). Glucose levels were measured at day 3 after cisplatin injection in serum, urine, and kidney tissue homogenates as described in Methods Results are expressed as the means ± SE. †P < 0.05compared to cisplatin, *P < 0.05, **P < 0.005 compared with control by unpaired Student’s t-test.