Expression of serum soluble Klotho protein in patients with renal damage induced by anti-neutrophil cytoplasmic antibody-associated small-vessel vasculitis and influence on prognosis

Abstract Background: Anti-neutrophil cytoplasmic antibody-associated small-vessel vasculitis (AASV) is an autoimmune disease with unclear pathogenesis, which causes damage to multiple organs and systems, renal failure or even death. We aimed to explore the expression of serum soluble Klotho protein in patients with AASV-induced renal damage and influence on prognosis. Methods: A total of 330 AASV patients treated from June 2012 to June 2014 were divided into renal damage and non-renal damage groups. Clinical symptoms and laboratory examination results were compared. They were divided into Klotho <935.05 pg/mL and ≥935.05 pg/mL groups, and renal damage and pathological indices were compared. Survival curves were plotted using Kaplan-Meier method, and 5-year and renal survival rates were compared. Results: Compared with the non-renal damage group, the mean arterial pressure, urine protein and blood creatinine levels significantly rose, while the red blood cell count, hemoglobin, serum albumin, and Klotho protein levels declined in the renal damage group (P<0.05). The optimal cut-off value of Klotho protein in assessing renal damage was 935.05 pg/mL. Compared with Klotho ≥935.05 pg/mL group, the levels of blood creatinine and urine protein significantly increased, and the proportion of normal glomeruli decreased, while that of fibrous crescents rose in Klotho <935.05 pg/mL group (P<0.05). The 5-year renal survival rate was significantly lower in Klotho <935.05 pg/mL group than that in Klotho ≥935.05 pg/mL group (P<0.05). Conclusions: Klotho protein is lowly expressed in patients with renal damage induced by AASV as a potential marker for early diagnosis and prognostic evaluation.