A number of studies have shown that proinflammatory cytokines have important roles in determining the development of microvascular diabetic complications, including nephropathy. Inflammatory biomarkers should be useful for diagnosis or monitoring of diabetic nephropathy. Mindin (spondin 2) is a member of the mindin-/F-spondin family of secreted extracellular matrix (ECM) proteins. Recent studies showed that mindin is essential for initiation of innate immune response and represents a unique pattern-recognition molecule in the ECM. Previously, we demonstrated that the levels of urinary mindin in patients with type 2 diabetes were higher than those in healthy individuals. We propose that urinary mindin is a potent biomarker for the development of diabetic nephropathy. 1. Introduction Diabetic nephropathy is a major cause of end-stage kidney disease (ESKD) in the United States, Japan, and most of Europe [1]. Although the etiology of this insidious disorder is not well understood, hyperglycemia and hypertension may play pivotal roles in the pathogenesis of diabetic nephropathy. Actually, almost 30% of diabetic patients develop diabetic nephropathy despite strict blood glucose and/or blood pressure control [2]. Chronic low-grade inflammation (so-called microinflammation) has been found to play roles in the pathogenesis of diabetes [3, 4] and has been identified as a risk factor for the development of diabetes [5, 6]. Moreover, diabetes has been proposed as a disease of the innate immune system [7]. In addition, the studies in recent years have shown that inflammation and inflammatory cytokines are determinants in the development of microvascular diabetic complications such as neuropathy, retinopathy, and nephropathy [8–11]. In 1991, Hasegawa et al. reported that glomerular basement membranes from diabetic rats induced significantly greater amounts of tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1) in cultured peritoneal macrophages than when these cells were incubated with basement membranes from nondiabetic rats [12]. Based on these findings, the authors suggested for the first time that inflammatory cytokines may participate in the pathogenesis of diabetic nephropathy [12]. At present, a number of clinical studies have suggested relationships between inflammatory cytokines and diabetic nephropathy [13, 14]. Inflammatory cytokines, that is, IL-1, interleukin-6 (IL-6), and interleukin-18 (IL-18) [15, 16], vascular endothelial growth factor (VEGF) [17, 18], monocyte chemoattractant protein-1 (MCP-1) [19, 20], and transforming growth factor-β (TGF-β)
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