Blood sampling as critical preanalytical determinant to use circulating MMP and TIMP as surrogate markers for pathological processes

Serum MMP-3 and its association with central arterial stiffness among young adults is moderated by smoking and BMI

Central arterial stiffness is an independent predictor of cardiovascular disease. It is characterized by a marked reduction in the elastin-collagen ratio of the arterial wall extracellular matrix (ECM), and is largely the result of degradation of various ECM components. Matrix metalloproteinase-3 (MMP-3) may contribute to central arterial stiffness via its involvement in ECM homeostasis and remodeling. This study examined the association between serum MMP-3 concentrations and central arterial stiffness and potential interactions of MMP-3 and traditional cardiovascular risk factors in a population of healthy young adults. A total of 206 participants (n = 109 females) aged 19-25 years were included in the current study. Central arterial stiffness was measured non-invasively as carotid-femoral pulse wave velocity (cfPWV) (m/s). MMP-3 concentrations (ng/ml) were measured using ELISA techniques. Regression analyses were used to examine the association between cfPWV and MMP-3, adjusting for age, sex, smoking status, body mass index (BMI), instantaneous mean arterial pressure (MAP) and heart rate, and serum C-reactive protein. Interactions between MMP-3 with smoking, BMI, sex, and MAP were analyzed in subsequent regression models. MMP-3 was an independent predictor of cfPWV (β = 0.187, p = 0.007), and significant interactions between MMP-3 and regular smoking (β = 0.291, p = 0.022), and MMP-3 and BMI (β = 0.210, p = 0.013) were observed. Higher serum MMP-3 concentrations were associated with a faster cfPWV and thus, greater central arterial stiffness. Interactions between MMP-3 and smoking, and MMP-3 and BMI may, in part, drive the association between MMP-3 and central arterial stiffness.

Serum Matrix Metalloproteinases and Left Atrial Remodeling-The Hoorn Study

Extracellular matrix protein turnover may play an important role in left atrial (LA) remodelling. The aim is to investigate the associations between matrix metalloproteinase (MMPs), tissue inhibitor of metalloproteinase (TIMP-1) and LA volume index (LAVI) and if these associations are independent of TIMP-1 levels. Participants from The Hoorn Study, a population-based cohort study (n = 674), underwent echocardiography. Serum MMPs (i.e., MMP-1, MMP-2, MMP-3, MMP-9, and MMP-10) and TIMP-1 levels were measured with ELISA. Multiple linear regression analyses were used. MMP-1 levels were not associated with LAVI. Higher MMP-2 levels were associated with larger LAVI (regression coefficient per SD increase in MMP (95% CI); 0.03 (0.01; 0.05). Higher MMP-3 and MMP-9 levels were associated with smaller LAVI; −0.04 (−0.07; −0.01) and −0.04 (−0.06; −0.02) respectively. Only in women were higher MMP-10 levels associated with larger LAVI; 0.04 (0.00; 0.07, p-interaction 0.04). Additionally, only in women were higher TIMP-1 levels associated with smaller LAVI; −0.05 (−0.09; −0.01, p-interaction 0.03). The associations between MMPs and LAVI were independent of TIMP-1 levels. In conclusion, serum MMPs are associated with LAVI, independent of CVD risk factors and TIMP-1 levels. In addition, these associations differ according to sex and within MMP subgroups. This shows that the role of MMPs in LA remodelling is complex.

Levels of matrix metalloproteinases differ in plasma and serum - aspects regarding analysis of biological markers in cancer

BACKGROUND

There are inconsistencies in the use of serum or plasma when analysing the matrix metalloproteinases (MMPs) as diagnostic or prognostic markers. The purpose of this study was to compare the concentration of MMP-1, -2, -7, -8, -9 and -13 in serum vs plasma samples.

METHODS

Blood samples were obtained from sixty-five men and women. Samples were analysed for levels of MMPs in corresponding citrate plasma and serum.

RESULTS

All MMPs expressed higher concentration in serum compared with plasma (P<0.01). There were no differences between genders.

CONCLUSIONS

Present study demonstrated significant differences regarding concentrations of some MMPs using plasma vs serum. We conclude that future studies regarding MMPs as biological markers in cancer should consider the use of citrate plasma instead of serum.

Reference intervals of plasma matrix metalloproteinases 2, 3, and 9 and serum asymmetric dimethylarginine levels

OBJECTIVE

The present study aimed to verify the reference intervals of plasma matrix metalloproteinases (MMPs) 2, 3, and 9 and serum asymmetric dimethylarginine (ADMA) in a healthy population with an average age corresponding to that of patients with cardiovascular diseases.

METHODS

The study included 180 healthy volunteers. Plasma MMP-2, MMP-3, MMP-9, and serum ADMA levels were determined using an enzyme-linked immunosorbent assay. These levels were analyzed for association with age and gender. The Cbstat5, R software, and NCSS 2007 programs were used for statistical analysis.

RESULTS

The average volunteer age was 47.4 years in the group in which MMP-3 and ADMA were analyzed, 40.3 years in the MMP-9 group, and 47.8 years for the MMP-2 group. Serum ADMA levels were determined to be independent of age and gender. Plasma MMP-2 levels were significantly correlated with age (p = 0.001), with lower levels detected in persons ≤ 49 years of age. Plasma MMP-3 was significantly associated with both age (p < 0.0001) and gender, with lower levels detected in persons of ≤ 47 years of age and among women. Plasma MMP-9 levels were not age dependent, but were associated with gender (p = 0.014), showing lower levels in women.

CONCLUSIONS

Reference intervals of heparin-plasma MMP-2, MMP-3, and MMP-9 and serum ADMA levels were determined. MMP-2 and MMP-3 levels were found to be age dependent, and MMP-3 and MMP-9 levels were gender dependent.

Assessing the value of matrix metalloproteinase 9 (MMP9) in improving the appropriateness of referrals for colorectal cancer

BACKGROUND

A blood test may be an effective means of improving the appropriateness of referrals for symptomatic patients referred to specialist colorectal clinics. We evaluated the accuracy of a serum matrix metalloproteinase (MMP9) test in indicating colorectal cancer or its precursor conditions in a symptomatic population.

METHODS

Patients aged over 18, referred urgently or routinely to secondary care following primary care presentation with colorectal symptoms completed a questionnaire and provided a blood sample for serum MMP9 estimation. Univariate analysis and logistic regression modelling investigated the association between presenting symptoms, MMP9 measurements and the diagnostic outcome of patient investigations, in order to derive the combination of factors which best predicted a high risk of malignancy.

RESULTS

Data were analysed for 1002 patients. Forty-seven cases of neoplasia were identified. Age, male gender, absence of anal pain, diabetes, blood in stools, urgent referral, previous bowel polyps and previous bowel cancer were significantly associated with neoplasia. Matrix metalloproteinase 9 measurements were not found to be associated with significant colorectal pathology.

CONCLUSION

This study, despite robust sampling protocols, showed no clear association between MMP9 and colorectal neoplasia. Matrix metalloproteinase 9 therefore appears to have little value as a tool to aid referral decisions in the symptomatic population.

Anticoagulants affect matrix metalloproteinase 9 levels in blood samples of stroke patients and healthy controls

OBJECTIVES

Matrix metalloproteinase-9 (MMP-9) represents a promising marker for acute stroke management. In clinical studies MMP-9 has been quantified by ELISA using differing protocols. We aimed to establish a valid protocol by evaluation of preanalytics.

DESIGN AND METHODS

Blood from stroke patients (n=28) and healthy controls (n=28) was drawn into tubes containing different anticoagulants (EDTA, citrate, lithium-heparin (heparin) and heparin with proteinase inhibitors) and processed after 0, 60 and 240 min. MMP-9 plasma protein and mRNA from mononuclear leukocytes were determined.

RESULTS

In regard to anticoagulants used, samples showed different MMP-9 protein baseline values and kinetics. Stable MMP-9 protein concentrations were only measured from EDTA samples. Particularly in samples with proteinase inhibitors protein and mRNA concentrations increased over time. Kinetics did not differ between patients and controls.

CONCLUSIONS

Preanalytics plays a key role for determination of MMP-9. EDTA seems to be a valid anticoagulant for MMP-9 protein measurement.

Translating molecular medicine into clinical tools: doomed to fail by neglecting basic preanalytical principles

This commentary discusses a study on measurements of matrix metalloproteinase 9 (MMP-9) in serum of pseudoxanthoma elasticum patients recently published in Journal of Molecular Medicine. This study can be considered the typical "obstacle" to effective translational medicine as previously documented in JTM journal. Although serum has been frequently proven as inappropriate sample for determining numerous circulating MMPs, among them MMP-9, there are over and over again studies, as in this case, that measure MMP-9 in serum. Comparative measurements in serum and plasma samples demonstrated higher concentrations for MMP-9 in serum due to the additional release from leukocytes and platelets following the coagulation/fibrinolysis process. From this example it can be concluded that translating basic research discoveries into clinical tools needs a more intensive exchange between basic biomedical research and clinical scientists already in an early stage. Otherwise a lost of translation, as discussed in JTM journal, seems to be inevitable.

Heparin affects matrix metalloproteinases and tissue inhibitors of metalloproteinases circulating in peripheral blood

OBJECTIVES

Blood sampling/handling alters matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) expression. The aim of this study is to evaluate the effects of high molecular weight heparin on MMP and TIMP expression in blood.

DESIGN AND METHODS

We analyzed by gelatin zymography and ELISA assays the effects of different heparin salts, dose- and time-dependence of MMP and TIMP concentrations in plasma and sera collected with and without clot-accelerator in plastic tubes from 50 healthy donors.

RESULTS

The levels and zymography of MMP-2 did not show significant changes among all samples, and during time- and dose-dependent heparin treatments. MMP-9 and TIMP-2 expression were strongly affected by heparin, with significant increase of their content and gelatinolytic activity both in time- and in dose-dependent fashion. Addition of heparin allowed also the displacement of MMP-2 prodomain, favouring zymogen activation.

CONCLUSIONS

Heparin has direct and indirect effects, altering MMP/TIMP complexes circulating in blood, and increasing the release of TIMP-2. To avoid misinterpretations due to MMP/TIMP complex alteration and MMP prodomain displacement, heparin should be cautiously used in blood collection procedures.

Biology and potential clinical implications of tissue inhibitor of metalloproteinases-1 in colorectal cancer treatment

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the industrialized world. About half of "curatively" resected patients develop recurrent disease within the next 3-5 years despite the lack of clinical, histological and biochemical evidence of remaining overt disease after resection of the primary tumour. Availability of validated biological markers for early detection, selection for adjuvant therapy, prediction of treatment efficacy and monitoring of treatment efficacy would most probably increase survival. Tissue inhibitor of metalloproteinases-1 (TIMP-1) may be such a marker. TIMP-1 inhibits the proteolytic activity of metalloproteinases, which are centrally involved in tumour invasion and metastases. However, in clinical investigations high tumour tissue or plasma levels of TIMP-1 have shown a strong and independent association with a shorter survival time in CRC patients, suggesting that TIMP-1 could have a tumour-promoting function. Furthermore, measurement of plasma TIMP-1 has been shown to be useful for disease detection, with a high sensitivity and high specificity for early-stage colon cancer. This review describes some basic information on the current knowledge of the biology of TIMP-1 as well as the potential use of TIMP-1 as a biological marker in the management of CRC patients.

TIMP-1 as a tumor marker in breast cancer--an update

Improvement of the management of breast cancer patients has high priority. In this regard, prognostic stratification needs to be improved in order to ensure proper medical treatment of all patients and furthermore predictors of response to chemotherapy are urgently needed. As new treatment opportunities emerge in the future this need will continue to grow. Thus, the search for molecular markers of prognosis and prediction is ongoing. Tissue Inhibitor of Metalloproteinases-1 (TIMP-1) has been suggested as a marker of both prognosis and response to treatment. Several studies have demonstrated the association between TIMP-1 and prognosis in breast cancer and new studies within this area have focused on the possibility of using blood samples or paraffin embedded tissue instead of tumor tissue extracts for measurements of TIMP-1. Interestingly, recent studies have investigated the association between TIMP-1 and response to treatment showing that TIMP-1 may also carry predictive information on response to treatment. In this regard, results from studies of the molecular functions of TIMP-1 point to a role of TIMP-1 in the inhibition of tumor cell apoptosis as an explanation for the clinical findings. This review gives an update on the ongoing investigation of the potential role of TIMP-1 as a tumor marker in breast cancer. Furthermore, we link the clinical findings with studies of the molecular actions of the TIMP-1 protein, raising hypotheses that may explain why TIMP-1 could play an important role in future management of breast cancer patients.

Differences in both matrix metalloproteinase 9 concentration and zymographic profile between plasma and serum with clot activators are due to the presence of amorphous silica or silicate salts in blood collection devices

Matrix metalloproteinases (MMPs) are promising diagnostic tools, and blood sampling/handling alters MMP concentrations between plasma and serum and between serum with and without clot activators. To explain the higher MMP-9 expression in serum collected with clot accelerators relative to serum with no additives and to plasma, we analyzed the effects of increasing amounts of silica and silicates (components of clot activators) in citrate plasma, serum, and buffy coats collected in both plastic and glass tubes from 50 healthy donors, and we analyzed the effects of silica and silicate on cultured leukemia cells. The levels of MMP-2 did not show significant changes between glass and plastic tubes, between serum and plasma, between serum with and without clot accelerators, or between silica and silicate treatments. No modification of MMP-9 expression was obtained by the addition of silica or silicate to previously separated plasma and serum. Increasing the amounts of nonsoluble silica and soluble silicate added to citrate and empty tubes prior to blood collection resulted in increasing levels of MMP-9 relative to citrate plasma and serum. Silica and silicate added to buffy coats and leukemia cells significantly induced MMP-9 release/secretion, demonstrating that both silica and silicate induce the release of pro- and complexed MMP-9 forms. We recommend limiting the misuse of serum and avoiding the interfering effects of clot activators.

Plasma and serum levels of tissue inhibitor of metalloproteinases-1 are associated with prognosis in node-negative breast cancer: a prospective study

The tumor level of TIMP-1 has been suggested as a new prognostic marker in breast cancer. The purpose of this study was to investigate whether TIMP-1 also carries prognostic information when measured in blood as this is a much more preferable material compared with tumor extracts. Using ELISA, TIMP-1 was measured in prospectively collected preoperative plasma and serum samples from 519 patients with primary breast cancer, and the measurements were related to patient outcome. The median age of the patients was 58 years (range, 38-80 years), and the median follow-up time was 1043 days (range, 300-1630 days). Plasma and serum TIMP-1 measurements correlated significantly with each other with a Pearson correlation coefficient of 0.75 (p < 0.0001). For univariate survival analysis, patients were divided into quartiles according to increasing TIMP-1 levels (Q1-Q4). Analysis of all patients showed that high TIMP-1 plasma levels were significantly associated with a shorter disease-free survival. Subgroup analysis showed that plasma TIMP-1 significantly predicted the prognosis of node-negative patients but not of node-positive patients. Importantly plasma TIMP-1 was able to further stratify low risk node-negative patients. High serum TIMP-1 levels were associated with a shorter disease-free survival; however, the association was not statistically significant. In contrast, serum TIMP-1 significantly predicted the prognosis of node-negative and low risk patients. In multivariate survival analysis of node-negative patients including all the classical prognostic parameters, plasma TIMP-1 remained significantly associated with prognosis when comparing Q1 with Q2 and Q4. Serum TIMP-1 remained significant when comparing Q1 with Q4. Taken together, this study is to our knowledge the first large prospective study suggesting that TIMP-1 carries independent prognostic information when measured in blood, especially plasma. This was especially true in the node-negative group of patients and in patients already defined as low risk patients using the currently available prognostic parameters.

Effects of anticoagulants on the activity of gelatinases

OBJECTIVES

To identify the best procedure for preanalytical blood collection in the determination of matrix metalloproteinase (MMP)-2 and -9 by testing the effects of anticoagulants on their activity.

DESIGN AND METHODS

Active forms of both gelatinases were measured by specific activity assay systems in serum, plasma EDTA, plasma-heparin and plasma-citrate obtained from 20 healthy volunteers, as well as in a pooled serum sample before and after anticoagulant treatment.

RESULTS

: Active MMP-2 and MMP-9 mean concentrations were similar in serum and in plasma-citrate, higher in plasma EDTA than in serum, in plasma-heparin and in plasma-citrate, and lower in plasma-heparin than in serum and plasma-citrate. A similar trend was observed in untreated and treated pooled serum samples.

CONCLUSIONS

Our results indicate that MMP-2 and MMP-9 in their active forms are not released by platelets during blood clotting, whereas the use of calcium chelating anticoagulants can profoundly alter the activity of endogenous gelatinases. This suggests that the determination of active forms of MMP-2 and MMP-9 in serum samples represents a suitable procedure.

Soluble interleukin-2 receptor and metalloproteinase-9 expression in head and neck cancer: prognostic value and analysis of their relationships

In a series of 84 head and neck patients, a statistically significant correlation was observed between high serum soluble interleukin (IL)-2 receptor alpha (sIL-2Ralpha) (P = 0.034) and metalloproteinase-9 (MMP-9) concentrations (P = 0.036) at diagnosis and a shorter survival of these patients. As MMP-9 has been shown to mediate cleavage of IL-2Ralpha (CD25) by preactivated T cells, we looked for a relationship between MMP-9 expression and soluble IL-2Ralpha serum concentrations in these cancer patients. We did not find any correlation between intratumoral expression of MMP-9 or serum MMP-9 concentrations and serum sIL-2Ralpha levels. These results led us to reassess the role of MMP-9 in the release of sIL-2Ralpha. Treatment of Kit225 leukaemic cells with recombinant MMP-9 slightly decreased membrane CD25 expression and was associated with an increased concentration of sIL-2Ralpha in the supernatants. However, using a selective inhibitor of MMP-9 we did not succeed in specifically inhibiting the release of sIL-2Ralpha by the Kit225 cell line or by phytohaemagglutinin (PHA)-activated peripheral blood mononuclear cells. In addition, in a preclinical mouse model, basal serum sIL-2Ralpha concentrations and sIL-2Ralpha production by activated cells were not altered in MMP-9-deficient mice compared to wild-type mice. Interestingly, a broad spectrum metalloproteinase inhibitor inhibited the release of sIL-2Ralpha by PHA-activated peripheral blood mononuclear cells, suggesting that in contrast with current views concerning the major role of MMP-9 in the cleavage of membrane IL-2Ralpha, other proteases are involved in the shedding of sIL-2Ralpha. MMP-9 and sIL-2Ralpha appear therefore as independent prognostic markers in head and neck cancers.

Matrix Metalloproteinase-9 (MMP-9) polymorphisms in patients with cutaneous malignant melanoma

BACKGROUND

Cutaneous Malignant Melanoma causes over 75% of skin cancer-related deaths, and it is clear that many factors may contribute to the outcome. Matrix Metalloproteinases (MMPs) play an important role in the degradation and remodeling of the extracellular matrix and basement membrane that, in turn, modulate cell division, migration and angiogenesis. Some polymorphisms are known to influence gene expression, protein activity, stability, and interactions, and they were shown to be associated with certain tumor phenotypes and cancer risk.

METHODS

We tested seven polymorphisms within the MMP-9 gene in 1002 patients with melanoma in order to evaluate germline genetic variants and their association with progression and known risk factors of melanoma. The polymorphisms were selected based on previously published reports and their known or potential functional relevance using in-silico methods. Germline DNA was then genotyped using pyrosequencing, melting temperature profiles, heteroduplex analysis, and fragment size analysis.

RESULTS

We found that reference alleles were present in higher frequency in patients who tend to sunburn, have family history of melanoma, higher melanoma stage, intransit metastasis and desmoplastic melanomas among others. However, after adjustment for age, sex, phenotypic index, moles, and freckles only Q279R, P574R and R668Q had significant associations with intransit metastasis, propensity to tan/sunburn and primary melanoma site.

CONCLUSION

This study does not provide strong evidence for further investigation into the role of the MMP-9 SNPs in melanoma progression.

Combined determination of plasma MMP2, MMP9, and TIMP1 improves the non-invasive detection of transitional cell carcinoma of the bladder

Background

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) play a major role in the maintenance of extracellular matrix homeostasis and are involved in the process of tumour invasion and metastasis in several malignant tumour entities. The goal of this study is to evaluate the diagnostic value of various circulating MMPs and TIMPs in blood plasma for a non-invasive detection of transitional cell carcinoma of the bladder (TCC).

Methods

In this study the concentrations of MMP1, MMP2, MMP3, MMP9, their inhibitors TIMP1, TIMP2, and the MMP1/TIMP1-complex (MTC1) were quantified in blood plasma with the sandwich enzyme-linked immunosorbent assay (ELISA). Blood plasma samples were investigated from 68 patients (non-metastasized, n = 57 and metastasized, n = 11) with TCC of the bladder and from 79 healthy controls. The mROC program was used to calculate the best two- and three- marker combinations. The diagnostic values for all single markers and the marker combinations were estimated both by the overall diagnostic performance index area under the ROC curve (AUC) and the sensitivity and specificity at cutoff limits with the highest diagnostic accuracy and at the 90% and 95% limits of sensitivity and specificity, respectively.

Results

The median MMP2 concentration was elevated in blood plasma in all patient groups with TCC in comparison to the controls (p < 0.001). The concentrations of TIMP1, TIMP2, and MTC1 in plasma probes were significantly lower from patients with non-metastasized TCC compared to the controls. MMP2 tested alone reached the highest sensitivity and specificity at 75%, respectively. The sensitivity and specificity increased when tested in combination with MMP9 and TIMP1 (97%, 94%, respectively). The combination of MMP9 and TIMP1 also showed an improved sensitivity (80%) and specificity (99%) than tested alone.

Conclusion

MMP2 is a statistically significant marker in blood plasma for bladder cancer detection with an increased diagnostic value in combination with MMP9 and TIMP1. This study showed that the highest sensitivities and specificities are not obtained by testing each marker alone. As shown by the best two-marker combination, which includes MMP9 and TIMP1, the optimized combination does not always include the best single markers.