Visceral adipose tissue-derived serine protease inhibitor: a unique insulin-sensitizing adipocytokine in obesity.

There is a rapid global rise in obesity, and the link between obesity and diabetes remains somewhat obscure. We identified an adipocytokine, designated as visceral adipose tissue-derived serpin (vaspin), which is a member of serine protease inhibitor family. Vaspin cDNA was isolated by from visceral white adipose tissues (WATs) of Otsuka Long-Evans Tokushima fatty (OLETF) rat, an animal model of abdominal obesity with type 2 diabetes. Rat, mouse, and human vaspins are made up of 392, 394, and 395 amino acids, respectively; exhibit approximately 40% homology with alpha1-antitrypsin; and are related to serine protease inhibitor family. Vaspin was barely detectable in rats at 6 wk and was highly expressed in adipocytes of visceral WATs at 30 wk, the age when obesity, body weight, and insulin levels peak in OLETF rats. The tissue expression of vaspin and its serum levels decrease with worsening of diabetes and body weight loss at 50 wk. The expression and serum levels were normalized with the treatment of insulin or insulin-sensitizing agent, pioglitazone, in OLETF rats. Administration of vaspin to obese CRL:CD-1 (ICR) (ICR) mice fed with high-fat high-sucrose chow improved glucose tolerance and insulin sensitivity reflected by normalized serum glucose levels. It also led to the reversal of altered expression of genes relevant to insulin resistance, e.g., leptin, resistin, TNFalpha, glucose transporter-4, and adiponectin. In DNA chip analyses, vaspin treatment resulted in the reversal of expression in approximately 50% of the high-fat high-sucrose-induced genes in WATs. These findings indicate that vaspin exerts an insulin-sensitizing effect targeted toward WATs in states of obesity.

Multicentric Castleman's disease associated with glomerular microangiopathy and MPGN-like lesion: does vascular endothelial cell-derived growth factor play causative or protective roles in renal injury?

A 52-year-old Japanese man presented with fever spikes, generalized fatigue, anorexia, and anasarca. The patient was referred for the evaluation of fever of unknown origin in association with swelling of cervical, axillary, and inguinal lymph nodes. He also manifested nephrotic syndrome, acute renal failure, hepatosplenomegaly, massive pleural effusion, ascites, disseminated intravascular coagulation, and hypergammaglobulinemia. C-reactive protein was positive and plasma vascular endothelial cell-derived growth factor (VEGF) and serum interleukin-6 levels were markedly elevated. Lymph node biopsy results showed that findings were compatible with Castleman's disease of hyaline vascular type associated with interfollicular plasmacytosis. In conjunction with the clinical findings, a diagnosis of multicentric Castleman's disease was made. The patient underwent renal biopsy because of nephrotic syndrome, and the results showed proliferation of mesangial cells, lobulation of glomeruli, and tram track pattern of the capillary wall without immune complex deposition. Electron microscopy showed widening of the subendothelial space. No electron-dense deposits were present in both mesangial and subendothelial regions. Pathologic features were compatible with glomerular microangiopathy and membranoproliferative glomerulonephritis-like lesions. With corticosteroid therapy, systemic symptoms disappeared; both VEGF and interleukin-6 levels were normalized, and he went into complete remission of nephrotic syndrome. In this article, the role VEGF plays in the pathogenesis of nephrotic syndrome and glomerular microangiopathy is discussed.