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AB0168 1,25 DIHYDROXYVITAMIN D IMPROVEMENTS ARTHRITIS BUT DOES NOT ALLEVIATE RENAL DAMAGE IN PRISTANE-INDUCED LUPUS MODEL

Background: SLE is an autoimmune disease, characterized by the production of autoantibodies and tissue damage. The role of vitamin D (VD) in SLE has been increasingly explored. VD is a steroid hormone notably involved in the regulation of calcium and bone homeostasis, and its deficiency has been implicated in the development of SLE and other connective tissue diseases (2,3). The study of different murine models has provided a better understanding of these autoimmune phenomena. Pristane-induced lupus (PIL) represents a suitable model to study factors that could influence the induction and/or progression of SLE, including genetic factors. Objectives: To evaluate the development and evolution of SLE after 1,25(OH)2D supplementation in the PIL model. Methods: Female BALB/c mice divided into 3 groups: CO, PIL and PIL+VD. Lupus was induced in PIL and VD groups using pristane. VD group received a subcutaneous injection of calcitriol [2ug/kg] in PBS-Tween 20 buffer every second day during 180 days. Body weight, arthritis clinical score, edema and articular nociception was measured. On day 150 after pristane induction, the animals were placed in individual metabolic cages for urine collection for a period of 12h. Protein levels on urine were analyzed using urine test strips. At the end of the experimental period, serum, tibiotarsal joint and kidneys was collected. Hind paws were collected to confirm the development of arthritis by histological analysis with HE staining. The glomerular cellularity was quantified by counting the total cell nuclei per glomerulus on HE slides. Immune complex deposition (IgG and IgM) in kidney was examined by direct immunofluorescence. IL-2, IL-4, IL-6, IFN-γ and TNF-α were measured by Luminex technology in serum. Data was analyzed with ANOVA Two-Way followed by Bonferroni and independent sample t-test. p<0.05 was considered significant. All data are represented as mean±SD. Results: PIL group showed arthritis and kidney injury, characterized by increased proteinuria, glomerular mesangial expansion and inflammation. Moreover, PIL model showed increased levels of IL-6, TNF-α and IFN-γ in serum. VD treatment reduced arthritis incidence compared PIL (42vs85%;p<0.01) at the end of the experimental period. The arthritis clinical score (1.00±1.15vs2.85±1.34;p<0.001) and the hind paws edema (0.20±0.03vs0.24±0.05 mL;p<0.05) in the VD group were also attenuated in relation to the PIL at day 180 after induction. VD was able to reduce synovial hyperplasia (0(0,1)vs2(2,3);p<0.05), erosion in bone (0(0,1)vs2(2,2);p<0.05) and cartilage (1(0,2)vs3(2,3);p<0.05) when compared to the PIL group. Treatment with VD was not able to reduce proteinuria levels (44.28vs47.14 mg/dL), decrease mesangial hypercellularity (31.48±2.6vs33.12±3.4nucleo/glomeruli) or IgG (17.88±6.0vs24.04±6.2) and IgM (12.62±6.9vs15.57±3.7) deposition in the kidney. VD supplementation did not alter IL-6, TNF-α, IL-2 and IL-4 cytokine levels, but reduce IFN-γ levels (p<0.01). Conclusion: VD improves arthritis but does not influence renal injury despite reducing IFN-γ levels. These results support that the role of VD may be different depending on acting site, what could explain different responses according clinical phenotype. Therefore, further investigations of VD are needed to explore the supplement dosage, timing, and the molecular basis in SLE. References [1] Pons-Estel GJ, et al. Seminars in Arthritis and Rheumatism. 2010. 2 Kamen DL, et al. Autoimmun Rev 2006; 5: 114–117. 3 Orbach H, et al. Ann N Y Acad Sci 2007; 1109: 385–400. Acknowledgement: FIPE/HCPA, CAPES, CNPq Universal Disclosure of Interests: None declared