Early markers of phenotypic heterogeneity in the induced model of systemic lupus erythematosus

The study aimed at evaluating the predisposition for development of different variants of SLE based on an inflammatory response in intact mice.Materials and methods. Low-dose systemic inflammatory response was modeled by the administration of lipopolysaccharide (LPS) of E. coli (strain 111: B4) by intact B6D2F1 recipients in the dose of 10 ng/mouse or 1 μg / mouse. We evaluated the number of leukocytes, neutrophils, and lymphocytes in the blood, the index of neutrophils / lymphocytes (ratio N/L), and the level of free DNA (cf DNA cell free) in dynamics. The first day after LPS injection we induced SLE model: the female B6D2F1 mice were injected 60–70 x 106 spleen cells of the DBA / 2 parent mice twice with interval five days. Three months after the induction of the model, the level of protein in the urine was measured twice: the mice with proteinuria 3 mg/ml and more were assigned to the group SLEnephritis+, and mice with less than 3 mg/ml of protein in the urine were assigned to the group SLEnephritis–.Results. It was established that administration of LPS does not change the frequency of nephritis in mice. The retrospective analysis of the number of leukocytes, neutrophils, and lymphocytes does not allow the prediction of the development of nephritis. We observed a significant increase in the frequency and the absolute value of the N/L index at week 8 relative to 4 weeks four weeks before the appearance of proteinuria in the group of mice SLEnephritis+ in contrast to mice SLEnephritis– when LPS was administered at a dose of 10 ng/mouse. Mice SLEnephritis+ and SLEnephritis– show different kinetics of the inflammatory response by an increase in the N/L index every subsequent hour relative to the previous one when LPS was administered at a dose of 1 μg/mouse. The dynamics of the cfDNA level is similar to the kinetics of an index N/L in the group SLEnephritis+ and the SLEnephritis–. The data obtained indicate the possibility of using of the index N/L and cfDNA level as a parameter of inflammatory response in mice and prediction of the susceptibility the development of nephritis