Kidney injury molecule-1 and microalbuminuria levels in Zambian population: biomarkers of kidney injury

Kidney injury molecule-1 and microalbuminuria levels in Zambian population: biomarkers of kidney injury

Mildred Zulu^1,&, Trevor Kaile¹, Timothy Kantenga², Chisanga Chileshe³, Panji Nkhoma⁴, Musalula Sinkala⁴

 

¹University of Zambia, School of Medicine, Department of Pathology and Microbiology, Lusaka, Zambia, ²University Teaching Hospital, Department of Pathology and Microbiology, Lusaka, Zambia, ³University of Zambia, School of Medicine, KS-HHV8 Research and Diagnostic Laboratory, Lusaka, Zambia, ⁴University of Zambia, School of Medicine, Department of Biomedical Sciences, Lusaka, Zambia

 

 

^&Corresponding author
Mildred Zulu, University of Zambia, School of Medicine, Department of Pathology and Microbiology, Lusaka, Zambia

 

 

 

 

Kidney injury is a condition in which the kidneys fail to function adequately. It is described as a decrease in the glomerular filtration rate [1]. Kidney malfunction frequently culminates to abnormal fluid levels in the body, deranged acid levels, abnormal levels of electrolytes, haematuria and anaemia [1, 2]. There are two forms of renal injury; acute kidney injury (AKI) and chronic kidney disease (CKD), which are indicative of the rate at which damage occurs, rather than the mechanisms by which it occurs [3]. It has been postulated that introduction of therapy early in the disease process would reduce the mortality rate associated with AKI and also delay the progression of CKD to end stage kidney disease (ESKD) [4]. The identification of reliable biomarkers for kidney injury would be useful to facilitate early intervention, evaluate the effectiveness of therapeutic interventions, and guide pharmaceutical development by providing an indicator of nephrotoxicity [4] The standard methods of assessing renal function have kept the measurement of serum blood urea nitrogen and creatinine, biomarkers that are insensitive and nonspecific, especially in the setting of AKI [5, 6]. Serum Creatinine levels are affected by non-renal factors such as age, gender, race, muscle mass, protein intake and liver function [7, 8], whereas blood urea nitrogen is affected by protein intake, dehydration, liver function, gastrointestinal bleeding and steroid use [9]. Increase in creatinine levels is seen when 60-75% of nephrons are non-functional while increase in urea is seen when approximately 75% of the nephrons become malfunctional, and therefore, these markers are not reliable for the diagnosis of kidney damage [10].

 

It is also important to recognize that changes in serum creatinine and blood urea nitrogen concentrations primarily reflect functional changes in filtration capacity and are not true ‘injury markers’ [11]. There is a crucial need for better biomarkers of AKI for its timely diagnosis, for the prediction of severity and outcome and for the monitoring of proximal tubule injury in AKI but also for progression in chronic kidney disease (CKD) [12].

 

Kidney injury molecule-1 (KIM-1) is a type I transmembrane structural glycoprotein with a cleavable ectodomain (90 kDa) which is located in the apical membrane of dilated tubules [13, 14]. It is minimally expressed in healthy kidneys, but is rapidly up-regulated and expressed on the apical surface of renal epithelial cells of the proximal tubule in response to different forms of renal injury [13, 15]. It plays a role in limiting the autoimmune response to injury by phagocytosis of apoptotic bodies and other debris from the tubular lumen [16, 17]. Presence of KIM-1 in urine has been found to be highly specific for kidney injury because no other organ has been shown to express KIM-1 to a degree that would influence kidney excretion [9]. Tissue KIM-1 expression and urinary KIM-1 levels have been reported to be increased in renal damage models of experimental animal studies and in several human studies [8, 18]. However there is paucity of data on the levels of KIM-1 in Zambian patients with kidney disease

 

Microalbuminuria (MAU) is defined as the subclinical elevation of urinary albumin, predominantly due to abnormal urine excretion of albumin between 30 and 300µg/ml [19]. It has been described as a biomarker of kidney damage, end stage renal disease (ESRD) and a risk of developing cardiovascular disease. It has also emerged as a strong candidate in the prediction of renal risk in hypertensive and diabetic patients, and may signal the presence of functional and / or structural renal abnormalities that precedes and envisage the onset of GFR deterioration [19, 20]. The pathophysiological mechanisms underlying the presence of MAU are still not clear, though intra renal hemodynamic changes that are brought about by increased systemic blood pressure, or capillary leakiness at the glomerular level have been implicated with the latter reflecting a more generalized atherosclerotic vascular damage [20, 13].

 

Currently, kidney injury is typically diagnosed by measuring serum creatinine and blood urea nitrogen [5, 6]. However, these biomarkers are insensitive for the diagnosis of early kidney damage [10]. Due to the diagnostic shortfalls of current routine biomarkers for evaluation of early kidney damage, various novel biomarkers have been suggested for assessment of kidney injury, with KIM-1 being among the front-runners based on the prospects it has as a biomarker as shown in various studies. Here, we evaluated KIM-1 and MAU as biomarkers of kidney damage in patients with kidney disease in the Zambian population. Ethical Approval Consent & Permissions: The University of Zambia Biomedical Research Ethics Committee (UNZABREC) IRB00001131 of IORG0000774, approved the study protocol; approval reference No. 003-08-14. Written Informed consent was obtained from all study participants. Permission to conduct the study was obtained from the Directorate of Research and Graduate Studies (DRGS) of the University of Zambia and from the Medical Supretendant of the University Teaching Hospital of Zambia (UTH).

 

 

Study design, site and sampling methods: an analytical cross-sectional study was conducted at the UTH in Lusaka, Zambia, involving 40 individuals with confirmed kidney disease (cases) and 40 individuals without any past or present history of kidney disease (controls), from whom consecutive blood and urine specimens were collected. The two groups were matched for broad age categories and sex.

 

KIM-1 Estimation: KIM-1 concentration was determined using the NeoBioLab®Human HK0032 (United States) ELISA Kit; a quantitative competitive immunoassay for measurement of Human KIM-1 in urine according to the manufacturer’s protocol. MAU Estimation- MAU concentration was determined using the Fitzgerald® Industries International (United States) ELISA Kit, a quantitative competitive immunoassay for measurement of Human albumin in urine. Renal functional test estimation (creatinine, urea and electrolytes sodium, Potassium and Chloride) - were measured using the Beckman Coulter Olympus AU480 automated chemistry analyser.

 

Data analysis: the independent student’s t-test was used to compare mean values of urinary KIM-1, urinary MAU, creatinine, urea and electrolytes and Pearson’s correlation was used to assess for correlation. All statistical tests were performed at 5% significance level and differences were considered significant if 2-tailed p < 0.05.

 

 

There was no difference in KIM-1 concentration between the cases (participants with kidney disease) (2.82 ± 1.36ng/mL) and controls (participants without kidney disease) (3.29 ± 1.14ng/mL), t(69) = -1.565, p <0.122 (Figure 1 A). MAU concentration and creatinine concentration were significantly higher in the cases 130.8 ± 84.7µg/mL and 597.9 ± 553.3µmol/L respectively, than in controls 16.0 ± 20.4µg/mL and 72.4 ± 17.7µmol/L respectively, with statistical significance, t(75) = 8.316, p =0.001 and t(74) = 5.930, p =0.001 respectively (Figure 1 B and Figure 1 C, respectively).

 

KIM-1 showed a weak positive correlation to MAU in participants with kidney disease with statistical significant r = 0.326, p = 0.045 (Figure.2A), however KIM-1 showed a weak negative correlation to creatinine in participants with kidney disease without statistical significance r = -0.279, p = 0.090 (Figure 2 B). MAU showed a medium positive correlation to creatinine in participants with kidney disease with statistical significance, r = 0.556, p = 0.001 (Figure 2 C).

 

 

Our results showed that there was no difference in KIM-1 concentration between participants with kidney disease and those without (Figure 1 A). These results were inconsistent with other studies that found elevated KIM-1 levels in participants with renal disease [4, 10, 14, 15, 18]. The disparity in these findings could be attributed to pathophysiological changes of the kidney due to the drug treatment effect [15]. According to a study done by Seo et al (2013) [16], they found lowered KIM-1 levels after renal drug treatment [16]. They accordingly proposed that urinary KIM-1 may be a useful biomarker for evaluating and predicting tubulointerstitial repair; hence an indicator of response to treatment [12, 15]. These findings could be interpreted in line with our results based on the similarity that our study participants were also on renal drug treatment.

 

The probable role of KIM-1 as a biomarker of kidney injury might be explained in part by a weak positive correlation between urinary KIM-1 and MAU with statistical significance (Figure 2 A) These results were similar to other studies which showed a positive correlation between KIM-1 with MAU, serum creatinine and blood urea nitrogen (BUN) [7, 17]. Therefore, an increase in KIM-1 level could be associated with a rapid decline in renal function [17]. However, this positive correlation did not hold between KIM-1 and creatinine (Figure 2 B), demonstrating that unlike KIM-1 levels, which may decrease due to treatment effect, creatinine levels may continue to increase as renal function deteriorates [15]. Participants with kidney damage, nevertheless, had significantly higher levels of creatinine (Figure 1 B), urea, potassium and chloride, and significantly lower sodium levels (Table 1). These results were characteristic of kidney injury with a decline of renal function in the group with kidney disease [17, 21]. Specifically, failure of the kidneys to excrete urea and creatinine, and increased loss of potassium with impaired sodium reabsorption in kidney disease [22]. Furthermore, the group with kidney disease showed significantly higher MAU concentration than the control group (Figure 1 C). Increased MAU/ albuminuria signal an increased risk of death, cardiovascular disease and kidney disease progression [23, 24]. MAU has emerged as a strong candidate in the prediction of renal risk in hypertensive as well as diabetic patients, it has been proposed that this condition may signal the presence of functional and / or structural renal abnormalities that precede and predict the onset of GFR deterioration [25]. Our results demonstrate the importance of MAU as a biomarker of kidney injury in participants with kidney disease, which is further justified by the moderate positive correlation between MAU and creatinine with statistical significance (Figure 2 C). These results are similar to other studies, which reported a positive correlation between MAU and creatinine in impaired kidney function [26].

 

 

Our study showed that there was no difference in KIM-1 levels between participants with kidney disease and those without kidney disease. MAU levels and serum creatinine levels were consistently higher and positively correlated in participants with kidney disease. Thus, the finding shows that MAU and serum creatinine should be the biomarkers of choice for the diagnosis and monitoring of renal damage. However, prospective studies are needed to investigate the role of KIM-1 in predicting kidney injury or its reversibility following treatment.

 

 

The authors declare no competing interests.

 

 

All authors have read and agreed to the final manuscript.

 

 

This work -was financially supported by grant #5R24TW008873 administered by the Fogarty International Center of the National Institutes of Health and Funded by OGAC and OAR, and also by the University of Zambia Staff Development Office.

 

 

Table 1: clinical and biochemical mean difference between participants with kidney disease and controls without kidney disease

Figure 1: A) mean difference of KIM-1 Levels: KIM-1 levels by ELISA in 40 participants with kidney disease and 40 participants without kidney disease; B) mean difference of microalbumin levels: microalbumin levels by ELISA in 40 participants with kidney disease and 40 participants without kidney disease; C) mean difference of creatinine levels: serum creatinine levels by ELISA in 40 participants with kidney disease and 40 participants without kidney disease

Figure 2: correlations of microalbumin, creatinine and KIM-1 in participants with kidney disease: A) microalbumin showed a weak positive correlation to KIM-1 with statistical significance; B) serum creatinine showed a non-significant weak positive correlation to KIM-1; C) microalbumin showed a moderate positive correlation to creatinine with statistical significance

 

 

1. Liangos O, Perianayagam MC, Vaidya VS, Han WK, Wald R, Tighiouart H, MacKinnon RW, Li L, Balakrishnan VS, Pereira BJ et al. Urinary N-acetyl-beta-(D)-glucosaminidase activity and kidney injury molecule-1 level are associated with adverse outcomes in acute renal failure. Journal of the American Society of Nephrology: JASN. 2007;18(3):904-912. PubMed | Google Scholar


2. Bonventre JV. Pathophysiology of AKI: injury and normal and abnormal repair. Contributions to nephrology. 2010; 165:9-17. PubMed | Google Scholar


3. Urbschat A, Obermuller N, Haferkamp A. Biomarkers of kidney injury. Biomarkers : biochemical indicators of exposure, response, and susceptibility to chemicals. 2011;16 Suppl 1:S22-30. PubMed | Google Scholar


4. Han WK, Bailly V, Abichandani R, Thadhani R, Bonventre JV. Kidney Injury Molecule-1 (KIM-1): a novel biomarker for human renal proximal tubule injury. Kidney international. 2002;62(1):237-244. PubMed | Google Scholar


5. Ibrahim M, Boghdadya, Mostafa M, Naggara EL, Mahmoud M, Emaraa, Rania M, Shazlyb EL KSM. Kidney injury molecule-1 as an early marker for acute kidney injury in critically ill patients. Menoufia Medical Journal. 2013; 26:98-104. Google Scholar


6. Mori K, Nakao K. Neutrophil gelatinase-associated lipocalin as the real-time indicator of active kidney damage. Kidney international. 2007;71(10):967-970. PubMed | Google Scholar


7. Kin Tekce B, Tekce H, Aktas G, Sit M. Evaluation of the urinary kidney injury molecule-1 levels in patients with diabetic nephropathy. Clinical and investigative medicine Medecine clinique et experimentale. 2014;37(6):E377-383. PubMed | Google Scholar


8. Vaidya VS, Ramirez V, Ichimura T, Bobadilla NA, Bonventre JV. Urinary kidney Injury molecule-1: a sensitive quantitative biomarker for early detection of kidney Tubular injury. American Journal of Physiology Renal Physiology. 2006 Feb;290(2):F517-529. PubMed | Google Scholar


9. Ruggenenti P, Schieppati A, Remuzzi G. Progression, remission, regression of chronic renal diseases. Lancet (London, England). 2001;357(9268):1601-1608. PubMed | Google Scholar


10. Doi K, Yuen PS, Eisner C, Hu X, Leelahavanichkul A, Schnermann J, Star RA. Reduced production of creatinine limits its use as marker of kidney injury in sepsis. Journal of the American Society of Nephrology . 2009;20(6):1217-1221. PubMed | Google Scholar


11. Bonventre JV. Kidney injury molecule-1 (KIM-1): a urinary biomarker and much more - Nephrology, dialysis, transplantation: official publication of the European Dialysis and Transplant Association. European Renal Association. 2009;24(11):3265-3268. PubMed | Google Scholar


12. OgrizoviĆ SS. The Importance Of Kim-1 Determination In Tissue And Urine Of Patients With Different Kidney Diseases. Znacaj Odre?ivanja Kim-1 U Tkivu I Urinu Bolesnikasa Razli?itim .Bolestima Bubrega. 2010;29(4):304-309. PubMed | Google Scholar


13. Verdecchia P, Reboldi GP. Hypertension and microalbuminuria: the new detrimental duo. Blood pressure. 2004;13(4):198-211. PubMed | Google Scholar


14. Vaidya VS, Ferguson MA, Bonventre JV. Biomarkers of acute kidney injury. Annual review of pharmacology and toxicology. 2008;48:463-493. PubMed | Google Scholar


15. Waanders F, Vaidya VS, van Goor H, Leuvenink H, Damman K, Hamming I, Bonventre JV, Vogt L, Navis G. Effect of renin-angiotensin-aldosterone system inhibition, dietary sodium restriction, and/or diuretics on urinary kidney injury molecule 1 excretion in nondiabetic proteinuric kidney disease: a post hoc analysis of a randomized controlled trial. American journal of kidney diseases : the official journal of the National Kidney Foundation. 2009;53(1):16-25. PubMed | Google Scholar


16. Seo MS, Park MY, Choi SJ, Jeon JS, Noh H, Kim JK, Han DC, Hwang SD, Jin SY, Kwon SH. Effect of treatment on urinary kidney injury molecule-1 in IgA nephropathy. BMC nephrology. 2013;14:139. PubMed | Google Scholar


17. El-Ashmawy N, El-Zamarany E, Khedr N, Abd El-Fattah A, Eltoukhy S. Kidney injury molecule-1 (Kim-1): an early biomarker for nephropathy in type II diabetic patients. Int J Diabetes Dev Ctries. 2015;1-8. PubMed | Google Scholar


18. van Timmeren MM, van den Heuvel MC, Bailly V, Bakker SJ, van Goor H, Stegeman CA. Tubular kidney injury molecule-1 (KIM-1) in human renal disease. The Journal of pathology. 2007;212(2):209-217. PubMed | Google Scholar


19. Poudel B, Yadav BK, Nepal AK, Jha B, Raut KB. Prevalence and association of microalbuminuria in essential hypertensive patients. North American journal of medical sciences. 2012; 4(8):331-335. PubMed | Google Scholar


20. Futrakul N, Sridama V, Futrakul P. Microalbuminuria: a biomarker of renal microvascular disease. Renal failure. 2009;31(2):140-143. PubMed | Google Scholar


21. Levey AS, Coresh J, Balk E, Kausz AT, Levin A, Steffes MW, Hogg RJ, Perrone RD, Lau J, Eknoyan G. National Kidney Foundation practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Annals of internal medicine. 2003;139(2):137-147. PubMed | Google Scholar


22. Bishop ML, Fody EP, Schoeff LE. Clinical Chemistry, Techniques, Principles, Correlations, 6th edn. Philadelphia: Lippincott Williams and Wilkins; 2010. Google Scholar


23. Campese VM, Bianchi S, Bigazzi R. Association between hyperlipidemia and microalbuminuria in essential hypertension. Kidney Int Suppl. 1999;56(Suppl 71):S10-13. PubMed | Google Scholar


24. Zacharias JM, Young TK, Riediger ND, Roulette J, Bruce SG. Prevalence, risk factors and awareness of albuminuria on a Canadian First Nation: A community -based screening study. Biomed central public Health. 2012;12:290. PubMed | Google Scholar


25. Lesaic V. Serum and urinary Biomarkers determination and their significance in diagnosis of kidney disease. J of med biochemistry. 2010; 29:288-297. Google Scholar


26. Baghel M, Modala S, Kumar BJP, Parimaia P. Correlation of Creatinine Clearance and urine Microalbuminuria in type 2 Diabetes Mellitus. Inter J Basic and App Med Sci. 2014;2277(2103):182-186. PubMed | Google Scholar