Early Diagnostic Biomarker for Diabetic Nephropathy

A recent breakthrough research study has identified urinary Asymmetric to Symmetric dimethylarginine Ratio (ASR) as a potential biomarker for early prediction of Diabetic Nephropathy (DN). This research has been published in the journal Scientific Reports

The research was a multidisciplinary collaborative effort of scientists from the CSIR-National Chemical Laboratory (CSIR-NCL), Pune, and clinical researchers from the Madras Diabetes Research Foundation (MDRF), Chennai, and National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru. Dr Venkateswarlu Panchagnula (CSIR-NCL) and Dr Kuppan Gokulakrishnan (NIMHAMS and MDRF) are the lead scientists in this project while Dr V. Mohan (MDRF) is the lead clinician in the study. 

Diabetic Nephropathy is among the most significant long-term complications associated with type 2 Diabetes Mellitus (T2DM). The risk of End-Stage Renal Disease (ESRD) resulting in premature morbidity and mortality is estimated to increase 12-fold with diabetes. Microalbuminuria (MIC) is an early non-invasive marker of renal disease and its progression. However, it takes several years of diabetes for MIC to occur. Interventions are also much less effective in some patients with MIC who manifest advanced pathological changes. Development of sensitive early-stage disease markers and alternative diagnostic approaches are thus essential for the detection of DN.

Symmetric and asymmetric dimethylarginines (SDMA and ADMA) are structural isomers. Altered circulatory asymmetric and symmetric dimethylarginines have been independently reported in patients with end-stage renal failure suggesting their potential role as mediators and early biomarkers of nephropathy. These alterations can also be reflected in the urine. Asian Indians are known to be more prone to insulin resistance, predisposed to cardio-metabolic diseases, and DN. However, there is a lack of data on urinary ASR in relation to nephropathy in this high-risk population.

The researchers evaluated the efficiency of ASR using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI MS) from more than 500 people with varying levels of glucose intolerance as well as in patients with T2DM with or without DN. 

The highly selective MALDI MS/MS methodology and data processing algorithm were developed by Dr Panchagnula’s group at CSIR-NCL. MALDI MS, a mass spectrometry approach, is generally used for protein identification. The CSIR-NCL patented technology used MALDI MS/MS in a process for detecting isomeric biomarkers. This approach can easily be adaptable to the diagnostics laboratory environment. It is capable of accurately and rapidly determining the biomarker ratio in thousands of patient samples using a cost-efficient process. Method validation was performed by Dr Prabhakar Sripadi’s group from the Indian Institute of Chemical Technology, Hyderabad (CSIR-IICT).

The study found that the ASR profile is lower in MIC and Macroalbuminuria (MAC) suggesting that it has the potential to be used as an early diagnostic marker. The study was able to correctly identify 72% of MIC and 91% of MAC respectively among Asian Indians, a population that is currently considered the epicentre of the worldwide diabetes epidemic. 

“Early diagnosis of DN using a sensitive biomarker such as ASR is beneficial to detect the onset of DN and to prevent/delay the progression into overt nephropathy. Our work is a proof-of-concept that shows the use of ASR for assessing progressive DN and this could aid future studies to understand the biology of nephropathy and the search for new treatments,” says one of the lead researchers Dr Gokulakrishnan, Assistant Professor, Department of Neurochemistry, NIMHANS. He is also serving as a Visiting Scientist at MDRF.

“Dimethylarginines (DMAs) are susceptible to protein binding, which may result in differential recovery for normal and proteinuric urine samples. Therefore, any quantitative estimation of these biomarkers and eventually meaningful clinical interpretations would have to take this into account as urine from patients with kidney disease has significant protein content. Estimation of their ratios using our approach offers a robust alternative to individual quantitative measurements. In this context, the decreased ASR in patients with MIC and MAC in our study is an important finding,” explains Dr Panchagnula, Principal Scientist and Associate Professor from CSIR-NCL, also a lead author of this work. 

Dr V. Mohan from MDRF stated, “MAC is a strong predictor of disease progression that only develops at an advanced stage of DN. However, at this stage, little can be done to prevent the development of end-stage kidney failure. Our study reported ASR cut-points for identifying MIC and MAC, which is an important and clinically relevant finding.” 

Dr Gokulakrishnan also added, “This new study is significant because the findings should cause concern in a country where most treatment costs are paid out-of-pocket by patients, and highlight the urgent need for early diagnosis, effective prevention measures and search for novel therapeutic measures.” 

The research provides an insight into disease progression and timely prevention and management to reduce adverse outcomes of nephropathy in all patients with type 2 diabetes.