The BALB/c model of pristane-induced lupus (PIL) exhibits cognitive impairment features resembling neuropsychiatric lupus (NPLSE). Osteopontin (OPN) is associated with disease activity in SLE; however, its involvement in NPLSE is not yet entirely determined. Our study aims to elucidate the contribution of full-length OPN (OPN-FL) plasma expression, OPN N-half, and Spp1 to cognitive impairment in the PIL mice model. A total of 76 female BALB/c mice were divided into pristane (P), pristane plus lipopolysaccharide (P plus LPS) and control (C) groups. In behavioral tests, the P group showed cognitive and visuospatial memory impairment. Elevated plasma OPN FL levels were found in P compared to C groups (177.7 ± 90.1 vs. 105.9 ± 56.8 ng/mL, p = 0.009) and OPN N-half was different between P and C groups (673.5 ± 144.6 vs. 624.5 ± 377.7 ng/mL, p = 0.028) and P plus LPS and C groups (624.5 ± 377.7 vs. 381.4 ± 205.0 ng/mL, p = 0.001). Anti-Sm correlated with OPN-FL (r = 0.269, p = 0.0150). The relative expression of Spp1 in the brain was 2.5 and 2.7-fold higher in P and P plus LPS groups, respectively. The evidence suggests that OPN is related to cognitive impairment in PIL mice and might play a relevant role in the detrimental neurological conditions of NPSLE.
Keywords: anti-Sm antibodies; neuropsychiatric lupus; osteopontin; pristane-induced lupus; spatial learning and memory; systemic lupus erythematosus.