Periostin: a novel tissue biomarker correlates with chronicity index and renal function in lupus nephritis patients.

Lupus nephritis (LN) is one of the most serious complications in patients with systemic lupus erythematosus (SLE). At present, there is no specific biomarker with high sensitivity and renal pathology involvement in use in clinical practice. Periostin is an extracellular matrix protein involved in kidney development and kidney injury. We performed immunohistochemical analysis for periostin and routine staining of 42 kidney tissues from LN patients compared with controlled kidney tissues. Activity index, chronicity index and periostin staining were evaluated and scored by a renal pathologist. Periglomerular staining of periostin was the most predominant finding. Positive periostin staining was also observed in areas with fibrosis such as sclerosed glomeruli, interstitial fibrosis and fibrous vessels. Moreover, the tubules seemed to be the main location for periostin staining. There was a statistically different level of periostin staining score between patient and control tissues. Periostin staining score also correlated with the chronicity index score of renal pathology (r = 0.594, p < 0.001). Periostin was also correlated with worsening renal outcomes including serum creatinine, blood urea nitrogen and estimated glomerular filtration rate (eGFR). Subgroup analysis within patients with low activity index score or low chronicity index score found that there was a statistical difference in serum creatinine and eGFR between groups with low and high periostin staining scores. We concluded that periostin staining score correlated with chronicity index score and renal function in patients with lupus nephritis.