Electronic Letters to:

Other Original Articles: K. C. Lewandowski, J. Komorowski, C. J. O’Callaghan, B. K. Tan, J. Chen, G. M. Prelevic, and H. S. Randeva Increased Circulating Levels of Matrix Metalloproteinase-2 and -9 in Women with the Polycystic Ovary Syndrome J Clin Endocrinol Metab 2006; 91: 1173-1177 [Abstract] [Full text] [PDF]

eLetters: Submit a response to this article

Electronic letters published:

Raised Matrix Metalloproteinases in Women with Polycystic Ovary Syndrome

Harpal S Randeva, Krysztof C Lewandowski   (1 February 2006)

Changed serum MMPs in polycystic ovary syndrome: due to illness or blood sampling?

Klaus Jung   (4 January 2006)

Raised Matrix Metalloproteinases in Women with Polycystic Ovary Syndrome 1 February 2006
Harpal S Randeva, Senior Lecturer University of Warwick, UK, Krysztof C Lewandowski Send letter to journal: Re: Raised Matrix Metalloproteinases in Women with Polycystic Ovary Syndrome hrandeva{at}bio.warwick.ac.uk Harpal S Randeva, et al.	We note the comments by Dr Klaus Jung in his recent letter, "Changed serum MMPs in polycystic ovary syndrome: due to illness or blood sampling?" (4 January 2006). We fully appreciate the technical problems associated with measurements of MMPs and their tissue inhibitors (TIMPs). As Dr Jung correctly points out, the measured levels of MMP9, in particular, are affected by the sampling method; we have also found about 10-fold differences between serum and plasma. For that reason, it is difficult to compare the values from different studies, and virtually impossible to define normal "reference values". To avoid these problems, our samples were collected in identical bottles on ice, and centrifuged and frozen within 30 minutes after collection, as we have done previously (1,2). Sampling methods were identical for controls and PCOS women, thereby suggesting that raised MMPs in women with PCOS may possibly be due to their inherent underlying ‘illness’, rather than merely due to sampling methodology. No matter what sample collection method/technique one uses, the source of MMPs cannot be precisely determined, and one cannot completely exclude a red cell contribution of MMPs/TIMPs. However, neither sample collection issues nor red cell contributions explain the significant near doubling of MMP 2 concentrations that we observed in PCOS women. Furthermore, the fact that levels of both metalloproteinases were higher makes it more likely to be a genuine finding related to the pro-inflammatory state of PCOS women. Finally, no matter what sampling method one uses, circulating MMPs/TIMPs levels cannot be associated with molecular changes in PCOS, no matter what pre-analytical conditions are used. References 1. Komorowski J, Pasieka Z, Jankiewicz-Wika J, Stepien H 2002 Matrix metalloproteinases, tissue inhibitors of matrix metalloproteinases and angiogenic cytokines in peripheral blood of patients with thyroid cancer. Thyroid 12:655-662 2. Randeva HS, Lewandowski KC, Komorowski J, Murray RD, O'Callaghan CJ, Hillhouse EW, Stepien H, Shalet SM 2004 Growth hormone replacement decreases plasma levels of matrix metalloproteinases (2 and 9) and vascular endothelial growth factor in growth hormone-deficient individuals. Circulation 109:2405-2410
Changed serum MMPs in polycystic ovary syndrome: due to illness or blood sampling? 4 January 2006
Klaus Jung, MD, Clinical Chemist Department of Urology, Res. Div., University Hospital Charité, 10098 Berlin, Germany Send letter to journal: Re: Changed serum MMPs in polycystic ovary syndrome: due to illness or blood sampling? klaus.jung{at}charite.de Klaus Jung	Lewandowski et al. (1) reported in their article that women with polycystic ovary syndrome (PCOS) had higher circulating levels of matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) than healthy women. The authors speculated that these changes could reflect, either as cause or consequence, the typical ovarian alterations of abnormal basement membrane rupture or follicular atresia observed in PCOS. They additionally proposed that increased MMP concentrations could contribute to the cardiovascular risk in these women. We believe that more attention should be paid to the impact of pre-analytical sample handling on the measurement of the MMPs and TIMPs in blood, as has been recently summarized in two cancer journals (2, 3). Measured MMP-9 concentrations depend on whether serum or plasma (heparin, citrate, EDTA) is used, and on the time required for sample preparation. For example, MMP-9 was found to be ~10 times higher in serum compared with citrate plasma, and ~3 times higher in serum prepared in tubes with clot activator than in serum samples without activator. In contrast, MMP-2 concentrations were less influenced by sample handling. TIMP-1 was also found ~5 times higher in serum than in plasma, while TIMP-2 was higher in heparin plasma than in serum and increased depending on the heparin concentration. These differences between plasma and serum are probably due to the different rates of release of MMPs and TIMPs from blood cells during the sampling process. In fact, serum MMP-9 and TIMP-1 are misleading biomarkers and do not represent the true circulating levels, but rather the high nonspecific background release from blood cells. For determining true concentrations of circulating MMP-2 and MMP-9 citrate plasma has been suggested as sample of choice (4). Lewandowski et al. (1) measured these analytes in serum collected under conditions that are not clearly defined. Consequently, direct associations between serum concentrations of MMP-9 and TIMP-1 and molecular changes in PCOS remain to be verified under appropriate pre-analytical conditions. References 1. Lewandowski KC, Komorowski J, O'Callaghan CJ, Tan BK, Chen J, Prelevic GM, Randeva HS 2005 Increased circulating levels of matrix metalloproteinase -2 & -9 in women with the polycystic ovary syndrome. J Clin Endocrinol Metab Dec 6; Epub ahead of print 2. Jung K, Meisser A, Bischof P 2005 Blood sampling as critical preanalytical determinant to use circulating MMP and TIMP as surrogate markers for pathological processes. Int J Cancer 116:1000-1001 3. Zucker S, Cao J 2005 Measurement of matrix metalloproteinases in serum of patients with melanoma: snarled in technical pitfalls. Clin Cancer Res 11:5069-5070 4. Meisser A, Cohen M, Bischof P 2005 Concentrations of circulating gelatinases (matrix metalloproteinase-2 and -9) are dependent on the conditions of blood collection. Clin Chem 51:274-276 4. Meisser A, Cohen M, Bischof P 2005 Concentrations of circulating gelatinases (matrix metalloproteinase-2 and -9) are dependent on the conditions of blood collection. Clin Chem 51:274-276