Original Article: Glutathione-S-Transferase and Thiol Stress in patients with acute renal failure Mungli Prakash, Department of Biochemistry and Genetics, St Matthew’s University, School of Medicine, Grand Cayman, Cayman Islands, BWI, Vivekananda Kedage, Manjunatha S Muttigi, Department of Biochemistry, Nataraj K, Waqas Wahid Baig, Ravindra Prabhu Attur, Department of Nephrology, Kasturba Medical College, Manipal 576104, India Address For Correspondence: Dr. Prakash Mungli, Associate Professor in biochemistry and genetics, St Matthew’s University, School of Medicine, P.O.BOX 30992, Regatta Office Park, Leeward Three, Grand Cayman KY1-1204, Cayman Islands, BWI E-mail: prakashmungli@yahoo.co.in Citation: Prakash M, Kedage V, Muttigi MS, Nataraj K, Baig WW, Attur RP. Glutathione-S-Transferase and Thiol Stress in patients with acute renal failure. Online J Health Allied Scs. 2010;9(2):10 URL: http://www.ojhas.org/issue34/2010-2-10.htm Open Access Archives: http://cogprints.org/view/subjects/OJHAS.html and http://openmed.nic.in/view/subjects/ojhas.html Submitted: May 23, 2009; Accepted: Apr 25, 2010; Published: Jul 30, 2010 Abstract: Introduction: Tubular damage is common finding in acute renal failure (ARF). Various etiologies have been put forth to explain the tubular damage in ARF, one important mechanism among them is oxidative damage to renal tubules. Several bio- molecules including low-molecular weight peptides and en- zymes in urine have been proposed as early markers of renal failure. Current study has been undertaken to study the thiol stress and glutathione-S-transferase (GST) levels in ARF pa- tients. Method: 58 ARF patients and 55 healthy controls were selected based on inclusion and exclusion criteria. Serum thi- ols, GST, malanoldehyde (MDA) and urine thiols were de- termined by spectrophotometer based methods. Results: Ser- um thiols and urine thiols were significantly decreased (p<0.0001), and serum GST and MDA levels were signific- antly increased (p<0.0001) in ARF patients compared to healthy controls. Serum GST and MDA correlated positively in ARF cases (r 2 = 0.6938, p<0.0001). Conclusion: There is significant thiol stress and increased lipid peroxidation in ARF patients which leads to tubular cell membrane damage and re- lease of GST into blood stream and into urine. This may be possible mechanism for the increased presence of GST in ur- ine (enzymuria) found in other studies. Key Words: Glutathione-S-transferase; thiol stress; acute ren- al failure; urine thiols Introduction: Acute renal failure (ARF) is characterized by a sudden or gradual decline in glomerular filtration rate (GFR), a slow and steady accumulation of nitrogenous waste products, and an in- ability of the kidney to regulate the balance of sodium, electro- lytes, acid, and water.(1) The ischemic damage in ARF is gen- erally most severe in the early proximal tubule (S3 segment) and the thick ascending limb of the loop of Henle.(2) Poor oxygenation leads to a variety of secondary factors that pro- mote the development of tubular injury, including the intracel- lular accumulation of calcium, the generation of reactive oxy- gen species, depletion of adenosine triphosphate, and apoptos- is.(2-4) Many tubular enzymes have been studied as markers of the necrotic/apoptotic damage or dysfunction of (proximal) tubular cells. Three major origins have been identified: the lysosomes, the brush-border membrane, and the cytoplasm of the cells.(5,6) Several studies have demonstrated that increased urinary amounts of enzymes are useful to detect acute tubular damage at a very early stage, but increased enzymuria may also be in- duced by a reversible mild dysfunction of the cells not neces- sarily associated with irreversible damage. The usefulness of enzymuria may be obscured by the low threshold for release of tubular enzymes, even in response to injury that may not proceed to ARF.(7) However, enzymes are also released dur- ing chronic glomerular diseases, which might limit their use as a marker of tubular injury only.(8-11) Some of the best-char- acterized tubular enzymes to detect tubular injury are gluta- thione-S-transferases (GSTs), γ-glutamyl transferase (γ-GT ), alkaline phosphatase (AP), lactate dehydrogenase (LDH), NAG, fructose-1,6-biphosphatase, and Ala-(Leu-Gly)- aminopeptidase.(8,9) Increased urinary excretion of these pro- teins implies tubular injury. GSTs are important in intracellular binding and transport of numerous compounds, and play a central role in human detox- ification process. Human GSTs mainly consists of class Pi (GST π), Alpha (GST α), Mu (GST μ) and Theta (GST θ) en- zymes, each subdivided into one or more isoenzymes. They catalyze the conjugation of glutathione with wide variety of xenobiotics such as carcinogens, pharmacologically active agents, as well as reactive oxygen species (ROS). The conjug- ation may result in the formation of more water soluble and less biologically toxic molecules that may be easily excreted. In addition to detoxification, GSH is important in storage and transport of amino acids. The characteristic feature of the tripeptide GSH (γ-glutamylcysteinylglycine) is the presence of reactive sulphydryl (–SH) group donated by cysteine in GSH is provided by cysteine, and this dictates the chemistry of GSH.(12) 1 This work is licensed under a Creative Commons Attribution- No Derivative Works 2.5 India License Online Journal of Health and Allied Sciences Peer Reviewed, Open Access, Free Online Journal Published Quarterly : Mangalore, South India : ISSN 0972-5997 Volume 9, Issue 2; Apr-Jun 2010