Transcriptional study of hyperoxaluria and calcium oxalate nephrolithiasis in male rats: Inflammatory changes are mainly associated with crystal deposition

PLOS ONE, Nov 2019

Hyperoxaluria associated with renal deposition of calcium oxalate (CaOx) crystals causes renal injury and inflammation leading to number of diseases including chronic kidney disease (CKD). It is however, not been possible to separate the renal consequences of hyperoxaluria from that of CaOx crystal deposition. We decided to utilize ethylene glycol (EG) model where hyperoxaluria and CaOx crystal deposition can be separated in time. To test our hypothesis, male rats were made hyperoxaluric by administering EG, rats were euthanized and kidneys were extracted on day 14, when occasional crystal is seen in the kidneys and day 28, when all animals have developed renal CaOx crystal deposits. Total RNA was extracted for microarray analysis and genome wide analysis of differentially expressed genes was performed to investigate differences between hyperoxaluria and crystal induced alterations in the kidneys. Immunohistochemical and Hematoxylin and Eosin (H&E) staining was also done for macromolecules with significant role in stone formation. All EG fed rats became hyperoxaluric by day 7, showed a few crystal deposits on day 14, and had heavy crystal deposition by day 28. There were significant changes in the expression of genes encoding for NADPH Oxidases; macromolecular crystallization modulators; genes involved in inflammasome activation; and osteogenic marker genes. Results demonstrate major differences between hyperoxaluria and CaOx crystal induced changes in the kidneys. Injury and inflammation are mainly associated with crystal deposition indicating significant role played by crystal retention.

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Transcriptional study of hyperoxaluria and calcium oxalate nephrolithiasis in male rats: Inflammatory changes are mainly associated with crystal deposition

November Transcriptional study of hyperoxaluria and calcium oxalate nephrolithiasis in male rats: Inflammatory changes are mainly associated with crystal deposition Sunil Joshi 1 2 3 Wei Wang 1 2 3 Saeed R. Khan 1 2 3 0 RO1-DK078602, DK092311 and University of Florida Center for the Study of Lithiasis. Publication of this article was funded in part by the University of Florida Open Access Publishing Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript , USA 1 Funding: This study was supported by National Institutes of Health grant 2 Department of Pathology, Immunology & Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, United States of America, 2 Department of Urology, College of Medicine, University of Florida , Gainesville, Florida , United States of America 3 Editor: Nick Ashton, The University of Manchester , UNITED KINGDOM Hyperoxaluria associated with renal deposition of calcium oxalate (CaOx) crystals causes renal injury and inflammation leading to number of diseases including chronic kidney disease (CKD). It is however, not been possible to separate the renal consequences of hyperoxaluria from that of CaOx crystal deposition. We decided to utilize ethylene glycol (EG) model where hyperoxaluria and CaOx crystal deposition can be separated in time. To test our hypothesis, male rats were made hyperoxaluric by administering EG, rats were euthanized and kidneys were extracted on day 14, when occasional crystal is seen in the kidneys and day 28, when all animals have developed renal CaOx crystal deposits. Total RNA was extracted for microarray analysis and genome wide analysis of differentially expressed genes was performed to investigate differences between hyperoxaluria and crystal induced alterations in the kidneys. Immunohistochemical and Hematoxylin and Eosin (H&E) staining was also done for macromolecules with significant role in stone formation. All EG fed rats became hyperoxaluric by day 7, showed a few crystal deposits on day 14, and had heavy crystal deposition by day 28. There were significant changes in the expression of genes encoding for NADPH Oxidases; macromolecular crystallization modulators; genes involved in inflammasome activation; and osteogenic marker genes. Results demonstrate major differences between hyperoxaluria and CaOx crystal induced changes in the kidneys. Injury and inflammation are mainly associated with crystal deposition indicating significant role played by crystal retention. Introduction Oxalate is an organic compound found naturally in many foods such as spinach, rhubarb, beets, wheat bran, strawberries, almonds and peanuts [ 1 ]. Higher concentration of oxalate in the human body can lead to a number of pathological conditions including hyperoxaluria which can further lead to a large spectrum of diseases such as nephrocalcinosis, cardiomyopathy, cardiac conductance disorders, systemic oxalosis, renal failure and specially CaOx kidney stones. Hyperoxaluria is excessive urinary excretion of oxalate and can be classified into different types such as primary, secondary, idiopathic and enteric hyperoxaluria caused by a variety of factors including genetic defects or mutation of specific genes (Primary hyperoxaluria), eating oxalate rich foods (Secondary hyperoxaluria), interplay of dietary, genetic and environmental factors with unknown causes (Idiopathic hyperoxaluria) and due to fat malabsorption, jejunal bypass surgery, and modern gastric bypass (Enteric hyperoxaluria) [2±6]. Kidney stone formation is a chronic disease which is becoming widespread nowadays, both in the United States and globally. Due to increased prevalence in the US, it is causing a significant economic burden on US health care [ 7 ]. According to National Health and Nutrition Examination Surveys (NHANES) of US adults, kidney stone prevalence increased from 5.2% (1988±1994) to 8.4% (2007±2010) [ 7 ] and a recent study showed that the number of kidney stone patients increased from 1 in 20 persons to 1 in 11 persons since 1994. Among men, the prevalence was 10.6% as compared to 7.1% among women and Caucasians were more likely to report a history of kidney stones as compared to African American and Hispanic individuals [ 8 ]. Also, recent studies show a link between stone formation and hypertension, chronic kidney disease and even end stage renal disease [9±12]. To understand the pathogenesis of hyperoxaluria and CaOx stone formation, many animal models have been developed [13±15]. Two rat models in which hyperoxaluria is induced by the administration of the ethylene glycol (EG) or hydroxy-L-proline (HLP) [ 16 ] have been studied in detail. Previous research has shown that hyperoxaluria and renal CaOx crystal deposition produced reactive oxygen species (ROS), upregulated mineralization modulators [17± 20], caused lipid peroxidation, and renal cellular injury [16,21±23]. The fr (...truncated)


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Sunil Joshi, Wei Wang, Saeed R. Khan. Transcriptional study of hyperoxaluria and calcium oxalate nephrolithiasis in male rats: Inflammatory changes are mainly associated with crystal deposition, PLOS ONE, 2017, Volume 12, Issue 11, DOI: 10.1371/journal.pone.0185009