Cell-free DNA profiling in patients with lupus nephritis

Abstract

Background Increased level of cell-free DNA (cf-DNA) is associated with systemic lupus erythematosus (SLE) and might be related to disease activity. The aim of this study was to evaluate whether cfDNA integrity, size distribution and concentration of different cfDNA fractions is associated with lupus activity and kidney involvement. Methods Blood samples were collected from 43 SLE patients and 50 healthy controls. Nuclear and mitochondrial fractions of cfDNA and intracellular DNA were quantified by real-time qPCR. Sizing and quantification of total cfDNA level was performed on Bioanalyzer. Results We determined four parameters that characterized cfDNA profile: fragmentation index, ratio of intra- to extracellular mtDNA copy number, cfDNA concentration, and presence of 54–149 bp and 209–297 bp fragments. Patients with healthy-like cfDNA profile had higher eGFR ( P = 0.009) and more often no indications for kidney biopsy or less advanced lupus nephritis (LN) ( P = 0.037). In contrary, SLE patients with distinct cfDNA profile (characterized by increased cfDNA concentration and fragmentation, higher discrepancy between intra- to extracellular mtDNA copy number, and the presence of 54–149 bp and 209–297 bp fragments) had lower eGFR ( P = 0.005) and more often advanced LN or history of renal transplantation ( P = 0.001). Conclusions We showed that cfDNA profiling may help to distinguish SLE patients with renal involvement and severe disease course from patients with more favorable outcomes. We suggest cfDNA profile a promising SLE biomarker.

EBV load is associated with cfDNA fragmentation and renal damage in SLE patients

“…49 In our previous paper we reported that cfDNA fragmentation pattern significantly differed between SLE patients and healthy individuals. 36 We found that cfDNA fragments of 54-149 bp and 209-297 bp were absent in healthy individuals and present in approximately 30% of SLE patients. Interestingly, the presence of these cfDNA fragments was associated with impaired kidney function.…”

“…This study was a continuation of our previous study and patients' characteristics are presented in Table 1. 36…”

“…The recalculated number of peaks representing different cfDNA lengths was referred to as the fragmentation index described previously by our group. 36…”

“…35 We reported previously that cfDNA fragmentation pattern in SLE patients differed significantly from healthy population. 36 CfDNA in healthy population consisted of a few different DNA fragments lengths that corresponded to the apoptotic degradation pattern. CfDNA in majority of SLE patients was less uniformly fragmented.…”

“…SLE patients with high fragmentation index had significantly lower eGFR which suggested that non-uniformly fragmented cfDNA was associated with impaired kidney function in SLE. 36 The aim of this study was to verify whether EBV load was associated with cfDNA concentration or fragmentation and to evaluate how renal damage in SLE is linked to EBV and cfDNA.…”