ESPN 54th Annual Meeting

ESPN 2022


 
Is a concentration of extracellular DNA determined by etiology of AKI?
ALEXANDRA GAáL KOVALčíKOVá ĽUBOMíRA TóTHOVá 2 ĽUBICA JANOVIčOVá 2 PETER CELEC 2 ĽUDMILA PODRACKá 1

1- DEPARTMENT OF PEDIATRICS, NATIONAL INSTITUTE OF CHILDREN’S DISEASES AND FACULTY OF MEDICINE, COMENIUS UNIVERSITY, BRATISLAVA, SLOVAKIA
2- INSTITUTE OF MOLECULAR BIOMEDICINE, FACULTY OF MEDICINE, COMENIUS UNIVERSITY, BRATISLAVA, SLOVAKIA
 
Introduction:

 

Despite progress in the management and treatment of acute kidney disease (AKI), it is still a life-threatening entity with increasing prevalence. Regardless the etiology of AKI, a change in conventionally used marker creatinine occurs within several hours or days after damaging insult. This might limit early diagnostics of AKI and increase the risk of irreversible kidney scarring and progression to end-stage renal disease. Recently, extracellular DNA (ecDNA) is gaining popularity as a non-specific marker of tissue damage. ecDNA is released from disintegrated cell (apoptosis, necrosis, NETosis) into various body fluids including plasma and urine. Although several studies described its increased concentrations in AKI, no study rigorously investigated ecDNA in different AKI causes. Thus, we aimed to describe ecDNA concentrations and activity of DNAse in children with different etiologies of AKI as well as in animal models.

Material and methods:

In the study were included 28 children with AKI (9.67 ± 6.29) and 27 sex- and age-matched healthy controls (aged 8.57 ± 4.30 years). Patients were diagnosed with glomerulonephritis (GN – 11%), tubulo-interstitial nephritis (TIN – 40%), atypical hemolytic-uremic syndrome (aHUS – 30%) and other etiologies (19%). In the experimental part, the models of adenine nephropathy (n = 30), HUS (n = 30), ischemia-reperfusion injury (n = 14), and 5/6 nephrectomy (n = 24) were studied. Total ecDNA concentrations were determined using fluorescent method (Qubit dsDNA HS Assay Kit, Invitrogen, Carlsbad, CA, USA). Nuclear (ncDNA) and mitochondrial DNA (mtDNA) were quantified by real-time PCR.

Results:

Plasma ecDNA and ncDNA were significantly higher in AKI patients compared to controls (ecDNA: 5-fold higher, p<0.001; ncDNA: 10-fold higher, p<0.05). When comparing various etiologies of AKI, plasma ecDNA was significantly increased in TIN and HUS. Interestingly, ncDNA and mtDNA did not differ between AKI causes. Urinary ncDNA was higher in AKI patients compared to controls (800-fold, p<0.05). However, there was no difference in urinary ecDNA, ncDNA and mtDNA between different causes of AKI. Further, no difference in DNase activity between patients and controls was found. In animal models, increased plasma ecDNA was observed in adenine nephropathy (5-fold), HUS (4-fold) and IRI (1.5-fold) but not in 5/6 nephrectomy. Accordingly, similar results were observed in urinary ecDNA together with decreased DNase activity in AKI animals.

Conclusions:

 

Results of the clinical part and the animal experiment indicate that increase in ecDNA in AKI is cause dependent. The higher concentration of ecDNA observed only in tubulo-interstitial nephritis and aHUS is probably related to the development of inflammation. Limitation of this study is low number of participants in subgroups of different AKI etiologies. Further studies involving more patients should elucidate the role of inflammation in ecDNA releasing in different causes of AKI.

The work was support by the Grant Agency of Ministry of Education, Science, Research and Sport of the Slovak Republic VEGA 1/0234/18 and APVV-18-0287.