Physiological matrix metalloproteinase (MMP) concentrations: comparison of serum and plasma specimens

Abstract

KeywordsEDTA; particle-based flow cytometry; sample processingThe authors appreciate the critical comments of Professor K. Jung, and agree with his demonstration, here and elsewhere (1,2), that differences between serum and plasma samples exist for measurement of MMP-9. We also agree, and have cautioned in our original manuscript, that plasma is the preferred clinical specimen for measurement of both MMP-8 and MMP-9 (3). Serum levels of these MMPs are very likely influenced by release of MMPs following degranulation of leukocytes and platelets during the ex vivo blood clotting process in the specimen collection tube (4). Finally, we agree that clinical research studies reporting on circulating MMP concentrations should clearly specify the sample collection methodology. Serum samples utilized in our analyses were prepared using "gold top" BD Vacutainers® (with clot activators and silicon coating, Becton Dickinson and Company, Franklin Lakes, USA) #367382; by centrifugation at 3400 rpm (2000×g) for 5 min.We would challenge, however, the inference that serum is never "appropriate" for the physiological ascertainment of MMP concentrations or that conclusions relative to MMP-9 can be generalized to all MMP measurements. For disease states characterized by cellular inflammatory responses, such as multiple sclerosis (5,6) and coronary artery disease (7-9), or malignant proliferation of inflammatory cell types such as multiple myeloma (10,11) and chronic lymphocytic leukemia (12,13), differences in serum measurements of MMPs have been detected and may provide a marker of pertinent intracellular protease activity. Alternatively, elevated concentrations of MMPs in serum might emanate from a circulating cell-type associated with a pathological condition. Moreover, recognizing that serum concentrations of MMPs have been assayed in disease states to identify clinically relevant or prognostic biomarkers of disease activation (10), we would suggest that both age-appropriate and specimen-appropriate reference ranges (or control data) be used in the interpretation of MMP concentrations in biological fluids. Finally, in our laboratory, Fluorokine® MultiAnalyte Profiling (F-MAP) methods have been used effectively for the simultaneous measurement of multiple MMPs in various biological fluids, including plasma, serum and urine (data not shown) and these measurements and their interrelationships may provide useful information.To demonstrate that differences in plasma vs. serum MMP-9 concentrations cannot necessarily be generalized to all MMPs, we offer some additional clinical data. We have recently assayed paired plasma (potassium EDTA BD Vacutainers®) and serum ("redtop" BD Vacutainers® with clot activator and silicon coated) specimens for MMP-1, -2, -3, -8 and -9 using F-MAP

Age- and Gender-Dependent Changes in Connective Tissue Remodeling: Physiological Differences in Circulating MMP-3, MMP-10, TIMP-1 and TIMP-2 Level

“…There is no doubt that MMP-3 and TIMP-2 levels show no significant differences between plasma and serum samples [29] . At the same time, a significant correlation between serum and plasma MMP-3 levels was found in the Thrailkill et al [30] studies, indicating that both of these samples provide similarly pertinent clinical information. In contrast, TIMP-1 values were found higher in serum than in plasma [29,30] .…”

“…At the same time, a significant correlation between serum and plasma MMP-3 levels was found in the Thrailkill et al [30] studies, indicating that both of these samples provide similarly pertinent clinical information. In contrast, TIMP-1 values were found higher in serum than in plasma [29,30] . No data is available about how blood sampling affects the circulating MMP-10 level.…”

Receptor cleavage reduces the fluid shear response in neutrophils of the spontaneously hypertensive rat

“…Potential MMP-9 cleavage sites have been previously identified (40). We selected the MMP-9 concentration on the basis of measurements in normotensive and hypertensive plasma (2,3,6,38). At the end of the 20-min incubation, fMLP (final concentration 10 M) was added to the blood solution containing MMP-9.…”

Matrix Metalloproteinase-2 Dysregulation in Type 1 Diabetes

“…Specimens were analyzed in duplicate on a Luminex 100 Bioanalyzer (Luminex, Austin, TX) as previously described (minimal detection limit, 25.4 pg/ml) (17,18).…”