Urinary adiponectin as a new diagnostic index for chronic kidney disease due to diabetic nephropathy

Abstract

ObjectiveThe chronic kidney disease (CKD) is widely diagnosed on the basis of albuminuria and the glomerular filtration rate. A more precise diagnosis of CKD, however, requires the assessment of other factors. Urinary adiponectin recently attracted attention for CKD assessment, but evaluation is difficult due to the very low concentration of urinary adiponectin in normal subjects.Research design and methodsWe developed an ultrasensitive ELISA coupled with thionicotinamide-adenine dinucleotide cycling to detect trace amounts of proteins, which allows us to measure urinary adiponectin at the subattomole level. We measured urinary adiponectin levels in 59 patients with diabetes mellitus (DM) and 24 subjects without DM (normal) to test our hypothesis that urinary adiponectin levels increase with progression of CKD due to DM.ResultsThe urinary adiponectin levels were 14.88±3.16 (ng/mg creatinine, mean±SEM) for patients with DM, and 3.06±0.33 (ng/mg creatinine) for normal subjects. The threshold between them was 4.0 ng/mg creatinine. The urinary adiponectin levels increased with an increase in the CKD risk. Furthermore, urinary adiponectin mainly formed a medium-molecular weight multimer (a hexamer) in patients with DM, whereas it formed only a low-molecular weight multimer (a trimer) in normal subjects. That is, the increase in urinary adiponectin in patients with DM led to the emergence of a medium-molecular weight form in urine.ConclusionsOur new assay showed that urinary adiponectin could be a new diagnostic index for CKD. This assay is a non-invasive test using only urine, thus reducing the patient burden.

Proposal of De Novo Antigen Test for COVID-19: Ultrasensitive Detection of Spike Proteins of SARS-CoV-2

“…The experimental protocol was as follows [ 20 , 21 , 22 ]. A 100-μL solution of primary antibody, adjusted to 10 μg/mL in 50 mM Na 2 CO 3 (pH 9.6), was added to microplate wells and incubated at room temperature for 1 h. The microplates were incubated with 1% bovine serum albumin (BSA) in Tris-buffered saline (TBS) at room temperature for 1 h. Spike protein (100 µL, i.e., antigen) was added to each well and incubated at room temperature for 1 h with shaking.…”

Lipotoxicity and Diabetic Nephropathy: Novel Mechanistic Insights and Therapeutic Opportunities

“…Thus, recent studies have shown the beneficial effect of AdipoRon, an orally-active synthetic adiponectin agonist, which was able to reduce lipotoxicity and to improve insulin resistance, obesity-related disease, and DN and its complications [227][228][229][230]. AdipoRon reduced sphingolipids levels, which are closely related to lipotoxicity, inflammation and insulin resistance [189].…”

Development of fully automated and ultrasensitive assays for urinary adiponectin and their application as novel biomarkers for diabetic kidney disease

“…Previous studies conducted by western blotting analysis have identified monomers, LMW and MMW adiponectin in urine 6,13 . Our ultrasensitive manual ICT-EIA could identify four types of adiponectin (HMW, MMW, LMW and monomer) by measurement of urine samples after SEC 29 .…”

“…Immunoassay technology is widely used for detection of protein biomarkers and novel technologies are continuing to be developed [14][15][16][17][18][19][20][21] . Adiponectin is present in urine at very low concentrations (pg/mL levels) [4][5][6][7][8][9][10][11][12][13] and a commercial immunoassay kit do not have sufficient analytical sensitivity to detect these trace amounts 10 . In recent years, an ultrasensitive immunoassay system capable of measuring down to a concentration of pg/ mL or less has been put into practical use 22,23 .…”