UroToday - Angiogenesis is thought to be important in many chronic inflammatory disorders, including diabetic retinopathy, atherosclerosis, and inflammatory bowel disease. It has also been suggested that the angiogenic components of these diseases contribute to and exacerbate disease conditions. Increased levels of vascular endothelial growth factor (VEGF) have been detected in patients with asthma and have been shown to be correlated with the severity of the disease. Anti-VEGF therapy has been shown to ameliorate inflammation in animal models of chronic inflammatory bowel disease. This background forms the prelude to a very interested study by Kiuchi and colleagues from Osaka, Japan.

The authors note that VEGF is a crucial angiogenic factor, and its secretion is strictly regulated to form functional vessel networks. Pericytes are perivascular cells that wrap around microvessels and contact endothelial cells through discontinuities in the shared basement membrane. When vessels lose pericytes, they become tortuous and hemorrhagic. Abnormal activity of VEGF contributes to insufficient coverage of pericytes, resulting in leaky and hemorrhagic vessels.

Kiuchi and coworkers examined biopsy specimens from 30 patients with BPS/IC who demonstrated glomerulations on hydrodistention, and compared them with biopsies from 10 control patients who had isolated bladder tumors and no symptoms of voiding dysfunction. None of the control patients had glomerulations after distention. Immunohistochemical analysis for VEGF expression, microvessel density and immature microvessels was performed. Pericyte coverage of microvessels in the specimens was used as an indicator of mature microvessels, and pericytes were identified by double-immunohistochemistry for CD34 and α-smooth muscle actin.

The researchers generated data that allowed them to conclude that there is an increased VEGF and immature vascularization in the bladder biopsies from patients with BPS/IC, and VEGF expression was associated with the degree of pain experienced by the patients. Taken together, Kiuchi believes that VEGF might contribute to pain and promote the formation of immature vessels in the bladder of patients with BPS/IC. This increased immature vascularization might have a potential role in glomerulations in these patients.

Kiuchi H, Tsujimura A, Takao T, Yamamoto K, Nakayama J, Miyagawa Y, Nonomura N, Takeyama M, Okuyama A
BJU Int. 2009 Mar 4. (Epub ahead of print)
doi:10.1111/j.1464-410X.2009.08467.x

UroToday Contributing Editor Philip M. Hanno, MD, MPH

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