Sulfasalazine-induced renal and hepatic injury in rats and the protective role of taurine

Abstract

[...]the fluorescence intensity of the samples was assessed using a FLUOstar Omega® mul- tifunctional microplate reader with λ =485 nm and excitation λ =525 nm.30,31 emission Measurement of lipid peroxidation The amount of lipid peroxidation in rat kidney and liv- er was assessed by measuring thiobarbituric acid reactive substances (TBARS). [...]samples were centrifuged (10000 g for 5 min) and the absorbance of developed col- orin n-butanol phase was read at 532 nm using an Ultro- spec 2000®UV spectrophotometer.32 Kidney and liver glutathione content Tissue samples (200 mg) were homogenized in 8 mL of ice-cooled EDTA (20 mM).

Headnote

Article History:

Received: 24 May 2015

Revised: 19 Dec. 2015

Accepted: 26 Dec. 2015

ePublished: 28 March 2016

Keywords:

Anti-rheumatoid drugs

Drug-induced liver injury

Hepatotoxicity

Renal injury

Taurine

Abstract

Introduction: Sulfasalazine is a drug commonly administrated against inflammatory-based disorders. On the other hand, kidney and liver injury are serious adverse events accompanied by sulfasalazine administration. No specific therapeutic option is available against this complication. The current investigation was designed to evaluate the potential protective effects of taurine against sulfasalazine-induced kidney and liver injury in rats.

Methods: Male Sprague-Dawley rats were administered with sulfasalazine (600 mg/kg, oral) for 14 consecutive days. Animals received different doses of taurine (250, 500 and 1000 mg/ kg, i.p.) every day. Markers of organ injury were evaluated on day 15th, 24 h after the last dose of sulfasalazine.

Results: Sulfasalazine caused renal and hepatic injury as judged by an increase in serum level of creatinine (Cr), alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP). The levels of reactive oxygen species (ROS) and lipid peroxidation were raised in kidney and liver of sulfasalazine-treated animals. Moreover, tissue glutathione reservoirs were depleted after sulfasalazine administration. Histopathological changes of kidney and liver also endorsed organ injury. Taurine administration (250, 500 and 1000 mg/kg/day, i.p) alleviated sulfasalazine-induced renal and hepatic damage.

Conclusion: Taurine administration could serve as a potential protective agent with therapeutic capabilities against sulfasalazine adverse effects.

Introduction

Sulfasalazine is widely administered against rheumatoid arthritis and other inflammatory-mediated disorders such as Crohn's disease in the human.1 On the other hand, sev- eral cases of liver injury associated with sulfasalazine ther- apy have been reported.2-4 Hepatic injury induced by sul- fasalazine might lead to hepatic failure and requirement for liver transplantation, and even patient death.5-7 Some investigations also indicated impairment in renal function after sulfasalazine therapy.8,9 Sulfasalazine-induced renal injury might be potentially irreversible.10,11 No specific therapeutic agent has been developed against sulfasala- zine-induced organ injury.

The precise mechanism of sulfasalazine-induced kidney and liver injury is unknown. Some investigations indicat- ed the role of reactive oxygen species and oxidative stress in the organ injury induced by this drug.12,13 Furthermore, oxidative stress also has been reported to be involved in infertility as another side effect of sulfasalazine.14 As oxi- dative stress seems to be one of the mechanisms of sulfas- alazine-induced organ injury,12,13 it could be expected that administration of some antioxidants might be a therapeu- tic approach. Hence, chemicals that possess multifactorial protective activity including antioxidant properties may offer pharmacological value against sulfasalazine-induced organ injury.

Taurine (2-aminoethane sulfonic acid) is one of the most abundant amino acids in the human body. Although tau- rine is not a constituent of any structural proteins, many important physiological roles are attributed to this mol- ecule. Taurine has been proposed to be a cell membrane stabilizer, intracellular ion regulator, and antioxidant.15-17 Taurine has been considered for the treatment of a wide range of disease including epilepsy,18 diabetic complica- tions,19 and cardiovascular disorders,20 even though the underlying mechanisms involved were often unclear. Many investigations also indicated the hepatoprotective properties of taurine against xenobiotics-induced liver injury, including several drugs.17,21,22 Furthermore, there are several reports about the beneficial effects of taurine in renal disorders.23 It has also been found that taurine administration protected kidney against xenobiotics-in- duced renal injury.24-27

The current study was designed to investigate the poten- tial protective role of taurine supplementation against sul- fasalazine-induced renal and hepatic injury.

Material and methods

Chemicals

Taurine (2-amino-ethane sulfonic acid) was ob- tained from Acros (New Jersey, USA). Trichloroacetic acid (TCA),Thiobarbituric acid (TBA), Ethylenedi- aminetetraacetic acid (EDTA), phosphoric acid, 2-Ami- no-2-hydroxymethyl-propane-1, 3-diol (Tris) were ob- tained from Merck (Darmstadt, Germany). Kits for eval- uating biomarkers of renal and liver injury were obtained from Pars Azmun (Tehran, Iran). All salts used for prepar- ing buffer solutions were of analytical grade and obtained from Merck (Darmstadt, Germany).

Animals

Male Sprague-Dawley rats weighing 200-300 g were ob- tained from the Laboratory Animal Breeding Center, Shi- raz University of Medical Sciences, Shiraz, Iran. Animals were housed in plastic cages over hardwood bedding. There was an environmental temperature of 21-23°C with a 40% of relative humidity. Animals had free access to a normal standard chow diet and water.

Experimental setup

Animals were randomly divided into six groups contain- ing six rats in each. Rats were treated as follows: 1) Con- trol (Vehicle-treated group), 2) Sulfasalazine (600 mg/kg, oral), 3) Sulfasalazine (600 mg/kg, oral) + Taurine (250 mg/kg, i.p), 4) Sulfasalazine (600 mg/kg, oral) + Taurine (500 mg/kg, i.p), 5) Sulfasalazine (600 mg/kg, oral) + Tau- rine (1000 mg/kg, i.p), and 6) Taurine (1 g/kg, the highest dose of taurine, i.p).

We administered sulfasalazine at a dose of 600 mg/kg/day for 14 consecutive days which is a dosage scheme report- ed to cause kidney and liver injury in rats.12 At the end of experiments, animals were anesthetized (sodium thiopen- tal, 80 mg/kg, i.p.) and their blood, kidney, and liver were collected.

Serum biochemistry and organ histopathology

Mindray BS-200® auto analyzer and standard kits (Pars Azmun®) were used to measure alanine aminotrans- ferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and cratinine in animals serum28. For histopathological assess- ments, samples of kidney and liver were fixed in buffered formalin solution (0.4% sodium phosphate monobasic, NaH2PO4, 0.64% sodium phosphate dibasic, Na2HPO4, and 10% formaldehyde in distilled water). Paraffin-em- bedded sections of tissue were prepared and stained with hematoxylin and eosin (H&E) before light microscope viewing.29

Reactive oxygen species (ROS) formation

Reactive oxygen species in kidney and liver tissue was estimated by the method described by Gupta et al with some modifications.30 Kidney and liver tissues was ho- mogenized inice-cold Tris-HCl buffer (40 mM, pH=7.4) (1:10 w/v). Samples of the resulted tissue homogenate (100 µL) were mixed with Tris-HCl buffer (1 mL) and 5 µL of 2', 7'-dichlorofluorescein diacetate (10 µM). The mixture was incubated for 30 minutes in 37°C (Gyromax(TM) incubator shaker). Finally, the fluorescence intensity of the samples was assessed using a FLUOstar Omega® mul- tifunctional microplate reader with λ =485 nm and excitation λ =525 nm.30,31 emission

Measurement of lipid peroxidation

The amount of lipid peroxidation in rat kidney and liv- er was assessed by measuring thiobarbituric acid reactive substances (TBARS). The reaction mixture consists of thiobarbituric acid (0.375%, w/v), phosphoric acid (1% w/v, pH=2), and 500 µL of tissue homogenate (10% w/v in KCl, 1.15%). The mixture was heated in boiling wa- ter (100°C) for 45 min. After the incubation period, the mixture was cooled, then 2 ml of n-butanol was added and vigorously mixed. Finally, samples were centrifuged (10000 g for 5 min) and the absorbance of developed col- orin n-butanol phase was read at 532 nm using an Ultro- spec 2000®UV spectrophotometer.32

Kidney and liver glutathione content

Tissue samples (200 mg) were homogenized in 8 mL of ice-cooled EDTA (20 mM). Five milliliters of the prepared homogenate were mixed with 4 mL of distilled water and 1 mL of trichloroacetic acid (50% w/v). The mixture was centrifuged (10000 g, 4°C, 25 min). Then, 2 mL of the supernatant was mixed with 4mL of Tris-HCl buffer (pH=8.9), and 100 µL of DTNB (0.01 M in methanol). The absorbance of developed color was measured in 412 nm using an Ultrospec 2000®UV spectrophotometer.28

Statistical analysis

Data are given as the Mean±SEM. Comparison of data sets were performed by the one-way analysis of variance (ANOVA) with Tukey's multiple comparison test as a post hoc. Differences were considered statistically significant when p<0.05.

Results

Sulfasalazine administration (600 mg/kg/day for 14 days) caused a marked impairment of liver function as judged by the elevated level of serum ALT, LDH, AST, and ALP (Table 1). Moreover, serum cratinine was also significantly raised in sulfasalazine-treated animals (Table 1).

It was found that sulfasalazine administration caused a significant increase in tissue level of reactive oxygen spe- cies (ROS) in both liver and kidney of tested animals (Fig. 1). Liver and kidney ROS formation was associated with consequent lipid peroxidation (Fig. 2) and glutathione reservoirs depletion (Fig. 3).

Histopathological evaluation of animals' liver revealed a slight increase in hepatic inflammatory cells aggregation in sulfasalazine-treated rats (Fig. 4). Although taurine ad- ministration effectively decreased the serum markers of liver injury, there were no significant changes in the in- flammatory cells aggregation in the pre-portal area of the liver of sulfasalazine-treated animals when taurine was administered (Fig. 4).

Examination of renal tissue specimens revealed histo- pathological changes including interstitial inflammation, tubular atrophy and necrosis (Fig. 5) when animals were treated with sulfasalazine (600 mg/kg/day). Tubular atro- phy was detected in taurine-treated (250, 500 and 1000 mg/kg) groups which received sulfasalazine, but there was no sign of tubular necrosis in these groups (Fig. 5).

Discussion

Sulfasalazine-induced renal and hepatic injuries are two serious adverse events accompanied by its clinical admin- istration.7-9,33 Although the mechanism(s) of organ injury induced by sulfasalazine is still unclear, defect in cellular defense mechanisms and reactive oxygen species forma- tion are likely to be involved in the situation.12,13

Our findings of ROS formation and its consequent events including lipid peroxidation and tissue glutathione deple- tion confirms the occurrence of oxidative stress in liver and kidney after sulfasalazine administration.12,13 These findings could support the notion that oxidative stress, at least in part, is involved in sulfasalazine-induced kidney and liver injury. The impairment in cellular defense mech- anisms induced by sulfasalazine,12,13 might lead to the gen- eration of excess ROS and finally organ dysfunction. Mul- tiple intracellular targets are subject to be affected by ox- idative stress.34 Sulfasalazine-induced production of ROS might finally interact with cellular macromolecules, cause lipid peroxidation and protein degradation.

Sulfasalazine is cleaved to sulfapyridine and mesalazine by bacterial azoreductases in the large intestine. Sulfa- pyridine is almost completely absorbed compared with about 20-30% absorption for mesalazine. About 10-30% of sulfasalazine is also absorbed unchanged from the small intestine.35 It is not clear that whether the whole molecule of sulfasalazine and/or its intestinal metabolites is respon- sible for the oxidative stress induction and organ injury induced by this drug. More research on the fate of sul- fasalazine and its intestinal metabolites in the body might shed light on the mechanisms of kidney and liver injury in human.

A number of investigations about the antioxidant prop- erties of taurine in the lung,36,37 heart,38 kidneys,39,40 and liver 41,42 have been published. Antioxidant properties and other physiological roles of taurine such as osmoregula- tion, membrane stabilization and modulation of intracel- lular calcium levels are well established.15 In addition to its antioxidant properties, taurine might also be beneficial by increasing the activity of the intracellular antioxidant enzymes including glutathione peroxidase, catalase, and superoxide dismutase.24,42-44 The protective properties of taurine against sulfasalazine-induced kidney and liver in- jury might be attributed to its ability to stabilize bio-mem- branes, scavenging reactive oxygen species, reducing the production of lipid peroxidation end products and finally increasing the activity of cellular defense mechanisms.

Clinical presentation of sulfasalazine-induced renal inju- ry has typically been associated with interstitial nephritis, glomerulonephritis, nephrotic syndrome and acute renal failure.45,46 Taurine administration counteracted the dele- terious effects of sulfasalazine on renal tubular function in our study. Taurine might protect renal system through regulation of blood flow, scavenging reactive oxygen spe- cies, cell volume regulation, and immunomodulatory ac- tion.47,48 Taurine might also alter the concentration of the nephrotoxic agents in the kidney.49 Moreover, it has been reported that taurine alleviated oxidative stress in kidney tissue through protecting vital organelles such as mito- chondria.40

Taurine is the most abundant amino acid presented in high concentrations in mammalian tissues. Several inves- tigations indicated its safety in human even in very high doses.50 Hence, these unique properties make it an appro- priate agent to prevent drug-induced organ injury.

Conclusion

In conclusion, we suggest that taurine has a protective role in sulfasalazine-induced renal and liver injury prob- ably by attenuating oxidative stress and its consequences in these organs. Further future investigations are needed to reveal the exact mechanisms of protective properties of taurine against sulfasala- zine-induced side effects and finally to clarify the clinical significance of these findings.

Acknowledgments

Pharmaceutical Sciences Research Center of Shiraz University of Medi- cal Sciences is gratefully acknowledged for providing the technical facili- ties. This investigation was financially supported by the office of the Vice Chancellor of Research Affairs, Shiraz University of Medical Sciences (Grant No: #93-01-36-7612).

Ethical issues

All the experiments were performed in conformity with the guidance for care and use of experimental animals approved by the local ethical com- mittee at Shiraz University of Medical Sciences, Shiraz, Iran (#93-01-36- 7612).

Competing interests

There is none to be declared.

Sidebar

Research Highlights

What is current knowledge?

[radical] Sulfasalazine causes serious adverse reactions including renal and liver injury in patients.

[radical] Although the precise mechanism of organ injury induced by sulfasalazine is not clear, oxidative stress induction is suspected to be responsible for sulfasalazine adverse effects. [radical] Taurine has been proposed to act as an antioxidant, a cell membrane stabilizer, and intracellular ion regulator. Many protective properties are attributed to this amino acid.

What is new here?

[radical] There is no specific therapeutic option against sulfasalazine- induced renal and hepatic injury.

[radical] Taurine could be a suitable protective agent against sulfasalazine adverse effects as administration of this amino acid effectively alleviated sulfasalazine-induced kidney and liver injury in this study.

[radical] The protective properties of taurine are mediated, at least in part, by attenuating oxidative stress in kidney and liver.

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