Background DNA, nucleosomes, and other deoxyribonucleoproteins (DNP) are currently believed to be the key autoantigens in SLE. However, these extracellular DNP itself appear to be just a cellular debris without any essential physiological function. This contradiction could open up a potential for diminishing anti-dsDNA pathogenic effect by degradation of the autoantigen and ICs.
Objectives To evaluate efficacy and safety of experimental in vivo blood perfusion through DNase I-containing magnetic beads under preliminary short-term examination using rat model of SLE-like alterations of DNP elimination.
Methods In the experiments we used 20 female Wistar rats (50-54 weeks), randomized in 2 groups. All the experimental protocols fulfilled both the national ethical requirements and ETS 123. The SLE-like disorders of DNP elimination were simulated by method of N. Jiang et al  which was followed by intravenous injection of anti-dsDNA (1 mg/kg). Magnetic beads were synthesized using technique described by A.B. Zborovsky et al . In the experimental group after preliminary heparinization blood was perfused through mini column with DNase I-containing magnetic beads (0.2 ml) at 1 ml/min until overall perfusion volume 100 ml/kg had been reached. Beads for the placebo group didn't contain any active substance. Titers of IgG deposited in rat kidneys (IgGf) were measured by direct IF on kidney cryoslices, serum circulating immune complexes (CIC) by PEG precipitation assay, serum anti-dsDNA IgG by ELISA, and plasma DNA by fluorimetry with PicoGreen. CBC, total plasma protein, plasma creatinine, ALT, AST, and coagulation time were determined using conventional methods. All these measurements except IgGf were performed before and immediately after perfusion.
Results We didn't observed animal death as well as hemodynamic instability during perfusion. There was no significant differences between experimental and placebo groups in the initial marker means. We revealed distinct differences between the experimental and placebo control groups in DNA (p<0.001) and CIC concentrations (p<0.001) after the perfusion. Geometric mean of IgGf titer was significantly higher in placebo perfusion group comparing to perfusion through DNase I-containing beads (p=0.002). After the perfusion serum creatinine, being initially increased, demonstrated significant lowering in the experimental group comparing to placebo (p<0.001). Other markers didn't reveal any significant changes in both groups.
Conclusions We have demonstrated clear efficacy of the extracorporeal perfusion in vivo for preventing kidney damage by diminishing of circulating DNA and CIC. As we speculated, the modeling protocol simulates not only glomerular deposition of DNA-containing ICs, but also induced filtration disorder. Lowering of DNA and DNA-ICs by the perfusion could diminish the extent of kidney damage. There was no signs of blood cell destruction, hepatotoxicity, or DIC during the short-term experiment.
Jiang N, Reich CF 3rd, Pisetsky DS. Role of macrophages in the generation of circulating blood nucleosomes from dead and dying cells. Blood. 2003;102(6):2243-50.
Zborovsky AB, Gontar IP, Alexandrov AV, et al. Utilization potential of immobilized nanosystems in rheumatology. Doctor.ru. 2009;3:53-7. [in Russian]
Disclosure of Interest None declared