Matrix-metalloproteinases and their inhibitors are elevated in severe sepsis: Prognostic value of TIMP-1 in severe sepsis

Role of plasma matrix-metalloproteases (MMPs) and their polymorphisms (SNPs) in sepsis development and outcome in ICU patients

Matrix-metalloproteases (MMPs) and their tissue-inhibitors (TIMPs), modulated by different single nucleotide polymorphisms (SNPs), are critical in sepsis development. Ninety ICU severely septic and 91 ICU uninfected patients were prospectively studied. MMP-1 (−1607 1G/2G), MMP-3 (−1612 5A/6A), MMP-8 (−799 C/T), MMP-9 (−1562 C/T), and MMP-13 (−77A/G) SNPs were genotyped. Plasma MMPs (-1, -2, -3, -8, -9, -10, -13) and TIMPs (-1,-2,-4) were measured. AA homozygotes and A allele carriers of MMP-13 (−77 A/G) and 1G2G carriers of the MMP-1 (−1607 1G/2G) SNPs frequencies were different between septic and uninfected patients (p < 0.05), as well as plasma MMP-3, -8, -9 -10 and TIMP-2 levels (p < 0.04). No differences in MMPs levels among MMP-13 or MMP-1 SNPs genotypes carriers were observed. The area under the ROC curve for MMP-8 in the diagnosis of sepsis was 0.87 (95% CI 0.82–0.92), and that of CRP was 0.98 (0.94–0.998), whereas the area of MMP-9 in the detection of non-septic state was 0.73 (0.65–0.80), p < 0.0001 for all curves. Sepsis associated with increased MMP-8 and decreased MMP-9 levels in multivariate analysis (p < 0.0002). We report for the first time an association between MMP-13 and MMP-1 SNPs and sepsis. An independent association of MMP-8 and MMP-9 levels with sepsis was also observed.

Serum MMP-8 and TIMP-1 in critically ill patients with acute respiratory failure: TIMP-1 is associated with increased 90-day mortality

BACKGROUND

Matrix metalloproteinases (MMPs) likely have an important role in the pathophysiology of acute lung injury. In a recent study, high matrix metalloproteinases (MMP-8) levels in tracheal aspirates of pediatric acute respiratory distress syndrome (ARDS) patients were associated with worse outcome. In patients with sepsis, an imbalance between MMPs and their tissue inhibitors (TIMPs) has been associated with impaired survival. We hypothesized that the elevated systemic MMP-8 and TIMP-1 are associated with worse outcome in acute respiratory failure.

METHODS

This was a substudy of the observational FINNALI study conducted in 25 Finnish intensive care units over an 8-week period. All patients older than 16 years requiring mechanical ventilation for >6 hours were included. MMP-8 and TIMP-1 levels were analyzed from blood samples taken on enrollment in the study and 48 hours later. Laboratory analyses were performed by using immunofluorometric assay for MMP-8 and ELISA for TIMP-1. MMP-8 and TIMP-1 levels were compared between 90-day survivors and nonsurvivors. Survival was compared in quartiles based on TIMP-1 levels, and ROC analysis was performed to calculate areas under the curves. The relationship between MMP-8 and TIMP-1 levels and degree of hypoxemia was examined.

RESULTS

The final analyses included 563 patients. Admission TIMP-1 levels were higher in nonsurvivors, median 367 ng/mL (interquartile range 199-562), than survivors, median 240 ng/mL (interquartile range 142-412), WMWodds 1.68 (95% confidence interval [CI], 1.43-2.08). MMP-8 levels may have differed between survivors and nonsurvivors, WMWodds 1.20 (95% CI, 1.01-1.43), but no difference was found in the MMP-8/TIMP-1 molar ratio, WMWodds 0.83 (95% CI, 0.67-1.04). Difference in survival between quartiles based on TIMP-1 was significant (log-rank, P < 0.001). ROC analysis produced an area under the curve 0.63 (95% CI, 0.58-0.69) for TIMP-1. TIMP-1 was associated with severity of hypoxemia. TIMP-1 levels were higher in an ARDS subgroup than in the whole cohort, WMWodds 1.65 (95% CI, 1.15-2.44).

CONCLUSIONS

MMP-8 levels were possibly higher in 90-day nonsurvivors but performed poorly in predicting outcome. Increased systemic levels of TIMP-1 were associated with more severe hypoxemia and worse outcome in a large cohort of mechanically ventilated critically ill patients and in a subgroup of ARDS patients.

Association of sepsis-related mortality with early increase of TIMP-1/MMP-9 ratio

Objective

Higher circulating levels of tissue inhibitor of matrix metalloproteinases (TIMP)-1 at the time of severe sepsis diagnosis have been reported in nonsurviving than in surviving patients. However, the following questions remain unanswered: 1) Does TIMP-1/MMP-9 ratio differ throughout the first week of intensive care between surviving and non-surviving patients? 2) Is there an association between TIMP-1/MMP-9 ratio and sepsis severity and mortality during such period? 3) Could TIMP-1/MMP-9 ratio during the first week be used as an early biomarker of sepsis outcome? 4) Is there an association between TIMP-1/MMP-9 ratio and coagulation state and circulating cytokine levels during the first week of intensive care in these patients? The present study sought to answer these questions.

Methods

Multicenter, observational and prospective study carried out in six Spanish Intensive Care Units (ICUs) of 295 patients with severe sepsis. Were measured circulating levels of TIMP-1, MMP-9, tumour necrosis factor (TNF)-alpha, interleukin (IL)-10 and plasminogen activator inhibitor (PAI)-1 at day 1, 4 and 8. End-point was 30-day mortality.

Results

We found higher TIMP-1/MMP-9 ratio during the first week in non-surviving (n = 98) than in surviving patients (n = 197) (p<0.01). Logistic regression analyses showed that TIMP-1/MMP-9 ratio at days 1, 4 and 8 was associated with mortality. Receiver operating characteristic (ROC) curves showed that TIMP-1/MMP-9 ratio at days 1, 4 and 8 could predict mortality. There was an association between TIMP-1/MMP-9 ratio and TNF-alpha, IL-10, PAI-1 and lactic acid levels, SOFA score and platelet count at days 1, 4 and 8.

Conclusions

The novel findings of our study were that non-surviving septic patients showed persistently higher TIMP-1/MMP-9 ratio than survivors ones during the first week, which was associated with severity, coagulation state, circulating cytokine levels and mortality; thus representing a new biomarker of sepsis outcome.

TIMP-1 gene polymorphism: are genetics able to predict outcome of septic patients?

The multicenter study conducted by Lorente and coworkers - published in the previous issue of Critical Care - suggests that levels of tissue inhibitor of metalloproteinase (TIMP)-1 in association with the 372 T/C genetic polymorphism of TIMP-1 are promising markers to predict the clinical outcome of septic patients. TIMPs bind to active matrix metalloproteinases and, amongst other effects, inhibit their proteolytic activity of the extracellular matrix. Previous clinical studies showed increased plasma levels of TIMP-1 in nonsurvivors of sepsis, and showed associations between the 372 T/C genetic polymorphism of TIMP-1 and increased risk of developing certain diseases. In recent years, there has been great interest in understanding whether genetic determinants of the host response to systemic infections are associated with poor outcome. Furthermore, the pharmacogenomics of sepsis may allow us to target immune-modulating therapies. Measurement of TIMP-1 protein levels and TIMP-1 polymorphism 372 T/C in the intensive care setting could therefore be an attractive noninvasive tool to determine the outcome of septic patients, and might help to select patients potentially benefitting from a target-specific immune-modulatory therapy directed to matrix metalloproteinase/TIMP homeostasis.

Development of a genomic metric that can be rapidly used to predict clinical outcome in severely injured trauma patients

OBJECTIVE

Many patients have complicated recoveries following severe trauma due to the development of organ injury. Physiological and anatomical prognosticators have had limited success in predicting clinical trajectories. We report on the development and retrospective validation of a simple genomic composite score that can be rapidly used to predict clinical outcomes.

DESIGN

Retrospective cohort study.

SETTING

Multi-institutional level 1 trauma centers.

PATIENTS

Data were collected from 167 severely traumatized (injury severity score >15) adult (18-55 yr) patients.

METHODS

Microarray-derived genomic data obtained from 167 severely traumatized patients over 28 days were assessed for differences in messenger RNA abundance among individuals with different clinical trajectories. Once a set of genes was identified based on differences in expression over the entire study period, messenger RNA abundance from these subjects obtained in the first 24 hours was analyzed in a blinded fashion using a rapid multiplex platform, and genomic data reduced to a single metric.

RESULTS

From the existing genomic dataset, we identified 63 genes whose leukocyte expression differed between an uncomplicated and complicated clinical outcome over 28 days. Using a multiplex approach that can quantitate messenger RNA abundance in less than 12 hours, we reassessed total messenger RNA abundance from the first 24 hours after trauma and reduced the genomic data to a single composite score using the difference from reference. This composite score showed good discriminatory capacity to distinguish patients with a complicated outcome (area under a receiver-operator curve, 0.811; p <0.001). This was significantly better than the predictive power of either Acute Physiology and Chronic Health Evaluation II or new injury severity score scoring systems.

CONCLUSIONS

A rapid genomic composite score obtained in the first 24 hours after trauma can retrospectively identify trauma patients who are likely to develop complicated clinical trajectories. A novel platform is described in which this genomic score can be obtained within 12 hours of blood collection, making it available for clinical decision making.

The 372 T/C genetic polymorphism of TIMP-1 is associated with serum levels of TIMP-1 and survival in patients with severe sepsis

INTRODUCTION

Previous studies have found higher circulating levels of tissue inhibitor of matrix metalloproteinase (TIMP)-1 in nonsurviving septic patients than in surviving septic patients, and an association between the 372 T/C genetic polymorphism of TIMP-1 and the risk of developing certain diseases. However, the relationship between genetic polymorphisms of TIMP-1, circulating TIMP-1 levels and survival in patients with severe sepsis has not been examined, and this was the objective of the study.

METHODS

This multicentre, prospective, observational study was carried out in six Spanish ICUs. We determined the 372 T/C genetic polymorphism of TIMP-1 (rs4898), serum levels of TIMP-1, matrix metalloproteinase (MMP)-9, MMP-10, TNFα, IL-10 and plasma plasminogen activator inhibitor-1 (PAI-1). Survival at 30 days from ICU admission was the endpoint assessed. The association between continuous variables was carried out using Spearman's rank correlation coefficient or Spearman's rho coefficient. Multivariate logistic regression analysis was applied to determine the association between the 372 T/C genetic polymorphism and survival 30 days from ICU admission.

RESULTS

Of 275 patients with severe sepsis, 80 had genotype CC, 55 had genotype CT and 140 had genotype TT of the 372 T/C genetic polymorphism of TIMP-1. Patients with the T allele showed higher serum levels of TIMP-1 than patients without the T allele (P=0.004). Multiple logistic regression analysis showed that the T allele was associated with higher mortality at 30 days (odds ratio=2.08; 95% confidence interval=1.06 to 4.09; P=0.03). Survival analysis showed that patients with the T allele presented lower 30-day survival than patients without the T allele (χ2=5.77; P=0.016). We found an association between TIMP-1 levels and levels of MMP-9 (ρ=-0.19; P=0.002), MMP-10 (ρ=0.55; P<0.001), TNFα (ρ=0.56; P<0.001), IL-10 (ρ=0.48; P<0.001) and PAI-1 (ρ=0.49; P<0.001).

CONCLUSION

The novel findings of our study are that septic patients with the T allele in the 372 T/C genetic polymorphism of TIMP-1 showed higher serum TIMP-1 levels and lower survival rate. The determination of the 372 T/C genetic polymorphism of TIMP-1 thus has prognostic implications and could help in the selection of patients who may benefit from modulation of the MMP/TIMP balance.

Comparison of localized versus systemic levels of Matrix metalloproteinases (MMPs), its tissue inhibitors (TIMPs) and cytokines in tuberculous and non-tuberculous pleuritis patients

The interaction of Matrix metalloproteinases (MMPs), its tissue inhibitors (TIMPs) and pro-inflammatory cytokines in response to Mycobacterium tuberculosis (MTB) infection is important to understand the immune response at the site of infection. We compared the levels of MMPs, TIMPs and cytokines in plasma (BL) and pleural fluid (PF) of tuberculosis (TB) and non tuberculosis (NTB) patients. Comparison between BL and PF showed significantly higher levels of MMP-1, TIMP-1 and -3 in TB PF; of MMP-7, -8, -9 in BL of both groups. Also, levels of MMP-1,-8,-9 and TIMP-3 were significantly higher in TB PF compared to NTB. Cytokines INF-γ, TNF-α, and IL-6 significantly increased in PF of both groups. A positive correlation of MMPs with TIMPs in TB, MMP-1 and -9 with IL-6 in TB PF and MMP-9 with IFN-γ in NTB PF was observed. This study implicates the possible usage of MMPs as bio-markers aiding diagnosis in TB pleuritis.

Matrix metalloproteinases as therapeutic targets in protozoan parasitic infections

Matrix metalloproteinases (MMPs) are associated with processes of tissue remodeling and are expressed in all infections with protozoan parasites. We here report the status of MMP research in malaria, trypanosomiasis, leishmaniasis and toxoplasmosis. In all these infections, the balances between MMPs and endogenous MMP inhibitors are disturbed, mostly in favor of active proteolysis. When the infection is associated with leukocyte influx into specific organs, immunopathology and collateral tissue damage may occur. These pathologies include cerebral malaria, sleeping sickness (human African trypanosomiasis), Chagas disease (human American trypanosomiasis), leishmaniasis and toxoplasmic encephalitis in immunocompromised hosts. Destruction of the integrity of the blood-brain barrier (BBB) is a common denominator that may be executed by leukocytic MMPs under the control of host cytokines and chemokines as well as influenced by parasite products. Mechanisms by which parasite-derived products alter host expression of MMP and endogenous MMP inhibitors, have only been described for hemozoin (Hz) in malaria. Hence, understanding these interactions in other parasitic infections remains an important challenge. Furthermore, the involved parasites are also known to produce their own metalloproteinases, and this forms an extra stimulus to investigate MMP inhibitory drugs as therapeutics. MMP inhibitors (MMPIs) may dampen collateral tissue damage, as is anecdotically reported for tetracyclines as MMP regulators in parasite infections.

Tigecycline accelerates staphylococcal-infected burn wound healing through matrix metalloproteinase-9 modulation

OBJECTIVES

We investigated the in vivo efficacy of tigecycline, a new glycylcycline (a tetracycline derivative), in the management of methicillin-resistant Staphylococcus aureus (MRSA)-infected experimental surgical wounds in rats. The main outcome measures were quantitative bacterial culture, histological examination and immunohistochemical expression of matrix metalloproteinase-9 (MMP-9) and collagen IV.

METHODS

An animal model was used to compare the in vivo efficacy of teicoplanin and tigecycline in the treatment of burn wound infections by S. aureus. A copper bar, heated in boiling water, was placed on the paraspinal site of each rat, resulting in full thickness burns. A small gauze was placed over each burn and then inoculated with 5 × 10(7) cfu of S. aureus ATCC 43300. To mimic the clinical situation in burn patients, surgical debridement was performed 48 h after the injury. The wounds were left to heal by secondary intention. The study included an uninfected control group that did not receive any treatment, a contaminated group that did not receive any treatment, and two contaminated groups treated with intraperitoneal tigecycline (2 mg/kg) and teicoplanin (7 mg/kg), respectively.

RESULTS

All antibiotic treatments were significantly effective. Tigecycline showed the highest antimicrobial activity, with a better impact on histological results. Infected rats treated with tigecycline showed a significant decrease in MMP-9 expression both in epithelium and in dermis compared with rats treated with teicoplanin.

CONCLUSIONS

Tigecycline, besides its antimicrobial activity, exerts an important modulatory effect on MMP-9, accelerating wound healing in staphylococcal-infected burns.

A biomarker panel to discriminate between systemic inflammatory response syndrome and sepsis and sepsis severity

Introduction:

In this study, we report on initial efforts to discover putative biomarkers for differential diagnosis of a systemic inflammatory response syndrome (SIRS) versus sepsis; and different stages of sepsis. In addition, we also investigated whether there are proteins that can discriminate between patients who survived sepsis from those who did not.

Materials and Methods:

Our study group consisted of 16 patients, of which 6 died and 10 survived. We daily measured 28 plasma proteins, for the whole stay of the patients in the ICU.

Results:

We observed that metalloproteinases and sE-selectin play a role in the distinction between SIRS and sepsis, and that IL-1α, IP-10, sTNF-R2 and sFas appear to be indicative for the progression from sepsis to septic shock. A combined measurement of MMP-3, -10, IL-1α, IP-10, sIL-2R, sFas, sTNF-R1, sRAGE, GM-CSF, IL-1β and Eotaxin allows for a good separation of patients that survived from those that died (mortality prediction with a sensitivity of 79% and specificity of 86%). Correlation analysis suggests a novel interaction between IL-1α and IP-10.

Conclusion:

The marker panel is ready to be verified in a validation study with or without therapeutic intervention

Serum MMP-8, -9 and TIMP-1 in sepsis: high serum levels of MMP-8 and TIMP-1 are associated with fatal outcome in a multicentre, prospective cohort study. Hypothetical impact of tetracyclines

Recent evidence suggests that matrix metalloproteinases (MMPs) and their endogenous inhibitors are involved in the pathogenesis of sepsis. We studied serum levels of MMP-8, MMP-9 and TIMP-1 (tissue inhibitor of matrix metalloproteinase-1) in a multicentre, prospective cohort study of patients with sepsis treated in Intensive Care Units (ICUs). We analyzed serum samples taken on ICU admission from 248 critically ill sepsis patients. MMP-8, -9 and TIMP-1 serum levels were analyzed by enzyme-linked immunosorbent assays. Serum MMP-8, MMP-9 and TIMP-1 levels were significantly higher in patients with severe sepsis than in healthy controls. Serum MMP-8 levels among non-survivors (n=33) were significantly (p=0.006) higher than among survivors (n=215). Serum TIMP-1 but not MMP-9 levels were significantly higher among non-survivors than survivors (p<0.0001, p=0.079, respectively). Systemic MMP-8 is upregulated in sepsis suggesting that MMP-8 may contribute to the host response during sepsis. High serum MMP-8 and TIMP-1 levels at ICU admission were seen among patients with fatal outcome. With this background, clinical studies examining the ability of MMP-inhibitors (such as the non-antimicrobial properties of tetracyclines) to diminish the MMP-mediated inflammatory response are needed to develop novel therapies in order to improve the outcome of sepsis.

Matrix metalloproteinase inhibitor properties of tetracyclines: therapeutic potential in cardiovascular diseases

Matrix metalloproteinases (MMPs) are a family of proteases best known for their capacity to proteolyse several proteins of the extracellular matrix. Their increased activity contributes to the pathogenesis of several cardiovascular diseases. MMP-2 in particular is now considered to be also an important intracellular protease which has the ability to proteolyse specific intracellular proteins in cardiac muscle cells and thus reduce contractile function. Accordingly, inhibition of MMPs is a growing therapeutic aim in the treatment or prevention of various cardiovascular diseases. Tetracyclines, especially doxycycline, have been frequently used as important MMP inhibitors since they inhibit MMP activity independently of their antimicrobial properties. In this review we will focus on the intracellular actions of MMPs in some cardiovascular diseases including ischemia and reperfusion (I/R) injury, inflammatory heart diseases and septic shock; and explain how tetracyclines, as MMP inhibitors, have therapeutic actions to treat such diseases. We will also briefly discuss how MMPs can be intracellularly regulated and activated by oxidative stress, thus cleaving several important proteins inside cells. In addition to their potential therapeutic effects, MMP inhibitors may also be useful tools to understand the biological consequences of MMP activity and its respective extra- and intracellular effects.

Diagnostic and prognostic biomarkers of sepsis in critical care

Sepsis is a leading cause of mortality in critically ill patients. Delay in diagnosis and initiation of antibiotics have been shown to increase mortality in this cohort. However, differentiating sepsis from non-infectious triggers of the systemic inflammatory response syndrome (SIRS) is difficult, especially in critically ill patients who may have SIRS for other reasons. It is this conundrum that predominantly drives broad-spectrum antimicrobial use and the associated evolution of antibiotic resistance in critical care environments. It is perhaps unsurprising, therefore, that the search for a highly accurate biomarker of sepsis has become one of the holy grails of medicine. Procalcitonin (PCT) has emerged as the most studied and promising sepsis biomarker. For diagnostic and prognostic purposes in critical care, PCT is an advance on C-reactive protein and other traditional markers of sepsis, but is not accurate enough for clinicians to dispense with clinical judgement. There is stronger evidence, however, that measurement of PCT has a role in reducing the antibiotic exposure of critical care patients. For units intending to incorporate PCT assays into routine clinical practice, the cost-effectiveness of this is likely to depend on the pre-implementation length of an average antibiotic course and the subsequent impact of implementation on emerging antibiotic resistance. In most of the trials to date, the average baseline duration of the antibiotic course was longer than is currently standard practice in many UK critical care units. Many other biomarkers are currently being investigated. To be highly useful in clinical practice, it may be necessary to combine these with other novel biomarkers and/or traditional markers of sepsis.

Dynamic changes of matrix metalloproteinases and their tissue inhibitors in severe sepsis

PURPOSE

Little is known about the dynamic changes of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in sepsis. Our aim was therefore to investigate the time course of MMPs and their inhibitors in patients experiencing severe sepsis.

METHODS

Our prospective controlled analysis included 38 patients with severe sepsis. Plasma levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 were measured daily at a 5-day-long period with enzyme-linked immunosorbent assay. Seventeen healthy volunteers were invited as controls.

RESULTS

MMP-2 showed no difference compared to controls, whereas significantly elevated MMP-9 levels were detected on admission (P < .005). Significantly elevated but declining TIMP-1 levels were measured during the whole trial (P < .002-.004). Except for the second day, TIMP-2 levels were significantly lower than controls (P < .05-.009). MMP2/TIMP-1 ratios were significantly lower in septic patients (P < .03-.006), whereas MMP-2/TIMP-2 ratios were elevated throughout our study (P < .03-.006). MMP-9/TIMP-1 ratios were significantly lower at the first 3 days (P < .05-.008). MMP-9/TIMP-2 was significantly elevated on admission (P < .006).

CONCLUSIONS

Our research is the first follow-up study dealing with MMPs, TIMPs, and their ratios in severe sepsis. Our results indicate that MMPs and TIMPs may play a crucial role in severe sepsis, especially TIMP-1, MMP-9, and possibly TIMP-2, after an extensive study.

The pathogenesis of sepsis

Sepsis is a serious clinical condition that represents a patient's response to a severe infection and has a very high mortality rate. Normal immune and physiologic responses eradicate pathogens, and the pathophysiology of sepsis is due to the inappropriate regulation of these normal reactions. In an ideal scenario, the first pathogen contact with the inflammatory system should eliminate the microbe and quickly return the host to homeostasis. The septic response may accelerate due to continued activation of neutrophils and macrophages/monocytes. Upregulation of lymphocyte costimulatory molecules and rapid lymphocyte apoptosis, delayed apoptosis of neutrophils, and enhanced necrosis of cells/tissues also contribute to the pathogenesis of sepsis. The coagulation system is closely tied to the inflammatory response, with cross talk between the two systems driving the dysregulated response. Biomarkers may be used to help diagnose patients with sepsis, and they may also help to identify patients who would benefit from immunomodulatory therapies.

Elevated plasma matrix metalloproteinases and their tissue inhibitors in patients with severe sepsis

PURPOSE

Matrix metalloproteinases (MMPs) are essential for tissue remodeling. Our objectives were to determine (1) the concentrations of MMPs and their tissue inhibitors (TIMPs) in plasma obtained from patients with severe sepsis, (2) to correlate changes in MMP and TIMP levels with disease severity, and (3) to investigate recombinant activated protein C (rAPC) actions on plasma MMP2, 9 activities from severe sepsis patients.

MATERIALS AND METHODS

Matrix metalloproteinase and TIMP levels were quantified in plasma from patients with severe sepsis using antibody microarrays and gelatin zymography.

RESULTS

Plasma MMPs (3, 7, 8, 9) and TIMPs (1, 2, 4) on microarray were increased in severe sepsis on intensive care unit (ICU) day 1, with more than 3-fold increases in MMP3, MMP7, MMP8, MMP9, and TIMP4. Latent forms of MMP2, 9 on zymography were increased in plasma from patients with severe sepsis, whereas only half of severe sepsis patients showed active MMP9. Elevated MMP7 and MMP9 on ICU days 1 and 3 negatively correlated with multiple organ dysfunctions. The temporal activity patterns of MMP2, 9 during 21 ICU days were not altered in patients treated with rAPC or by the addition of exogenous rAPC to plasma.

CONCLUSION

Most plasma MMPs and TIMPS were elevated in patients with severe sepsis, but only a limited subset of MMPs (7, 9) negatively correlated with disease severity. Recombinant activated protein C does not appear to directly alter MMP2, 9 activities.

Systemically administered ligands of Toll-like receptor 2, -4, and -9 induce distinct inflammatory responses in the murine lung

Objective. To determine whether systemically administered TLR ligands differentially modulate pulmonary inflammation. Methods. Equipotent doses of LPS (20 mg/kg), CpG-ODN (1668-thioat 1 nmol/g), or LTA (15 mg/kg) were determined via TNF activity assay. C57BL/6 mice were challenged intraperitoneally. Pulmonary NFκB activation (2 h) and gene expression/activity of key inflammatory mediators (4 h) were monitored. Results. All TLR ligands induced NFκB. LPS increased the expression of TLR2, 6, and the cytokines IL-1αβ, TNF-α, IL-6, and IL-12p35/p40, CpG-ODN raised TLR6, TNF-α, and IL12p40. LTA had no effect. Additionally, LPS increased the chemokines MIP-1α/β, MIP-2, TCA-3, eotaxin, and IP-10, while CpG-ODN and LTA did not. Myeloperoxidase activity was highest after LPS stimulation. MMP1, 3, 8, and 9 were upregulated by LPS, MMP2, 8 by CpG-ODN and MMP2 and 9 by LTA. TIMPs were induced only by LPS. MMP-2/-9 induction correlated with their zymographic activities. Conclusion. Pulmonary susceptibility to systemic inflammation was highest after LPS, intermediate after CpG-ODN, and lowest after LTA challenge.

Expression of inflammation-associated genes in circulating leukocytes collected from horses with gastrointestinal tract disease

OBJECTIVE

To investigate whether expression of inflammation-associated genes in leukocytes from horses with gastrointestinal tract (GIT) diseases correlated with the type of disease and outcome.

ANIMALS

10 healthy horses and 50 horses with GIT disease.

PROCEDURES

A blood sample was collected from each healthy horse or horse with GIT disease (during admission to the hospital). Leukocytes were isolated, diluted to a standard concentration, and frozen until RNA extraction. Expression of 14 genes associated with inflammation was quantified by use of a real-time quantitative reverse transcription PCR assay. Results were grouped by GIT disease type and disease outcome for comparison.

RESULTS

Horses with GIT disease had colic of unknown etiology (n = 8 horses), GIT inflammation or strangulation (19), or nonstrangulating GIT obstruction (23). Among the 45 horses receiving treatment, 38 were discharged from the hospital, and 7 died or were euthanized. Compared with healthy horses, horses with colic of unknown etiology had similar gene expression. Significant differences in expression of the interleukin-8, leukocyte-selectin molecule, matrix metalloproteinase-9, platelet-selectin molecule, mitochondrial superoxide dismutase, Toll-like receptor 4, and tumor necrosis factor-A genes were detected between healthy horses and horses with GIT disease. Significant differences in expression of the interleukin-1 receptor antagonist, interleukin-8, leukocyte-selectin molecule, matrix metalloproteinase-9, platelet-selectin molecule, mitochondrial superoxide dismutase, Toll-like receptor 4, and tumor necrosis factor-A genes were detected among healthy horses and horses grouped by disease outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

Inflammatory gene expression in leukocytes of horses with GIT disease appeared to be related to disease pathogenesis and prognosis.

Matrix-metalloproteinase-2, -8 and -9 in serum and skin blister fluid in patients with severe sepsis

Introduction

Matrix metalloproteinases (MMPs) have various roles in inflammatory states. They seem to be able to modulate endothelial barriers and regulate the activity of chemokines and cytokines. The timely development of the levels during severe sepsis and thereafter have not been investigated. In addition it was of interest to study alterations of MMP-levels in intact skin, as the skin is the largest barrier against external pathogens and MMPs have not been studied at organ level in human sepsis. The aim of this study was to investigate the timely development of serum and skin MMP-2, -8 and -9 levels in human severe sepsis and their association with disease severity and mortality.

Methods

Forty-four patients with severe sepsis and fifteen healthy controls were included in this prospective longitudinal study. The amounts of MMP-2, -8 and -9 were analyzed from serum at days 1, 4, 6, 8, and 10, and from skin suction blister fluid at days 1 and 5 from the beginning of severe sepsis. Additionally, samples from the survivors were obtained after three and six months.

Results

The levels of MMP-2 and -8 were up-regulated in severe sepsis in comparison to healthy controls in skin blister fluid and serum. Compared to the controls MMP-9 levels were lower in sepsis from the fourth day on in serum and both the first and fifth day in skin blister fluid. Active forms of MMP-2 and -9 were present only in severe sepsis. The non-survivors had higher pro- and active MMP-2 levels than the survivors in skin blister fluid samples. Furthermore, MMP-2 levels were more pronounced in blister fluid and serum samples in patients with more severe organ failures. In the survivors at 3 and 6 month follow-up the MMP levels had returned to normal.

Conclusions

MMP-2 and -8 are elevated in serum and blister fluid in severe sepsis, implying that they may play a significant role in the pathogenesis of severe sepsis and organ dysfunctions. Active forms of MMP-2 and 9 were only present in patients with severe sepsis, and higher MMP-2 levels in skin blister and serum were associated with more severe organ dysfunctions.

Sepsis biomarkers: a review

INTRODUCTION

Biomarkers can be useful for identifying or ruling out sepsis, identifying patients who may benefit from specific therapies or assessing the response to therapy.

METHODS

We used an electronic search of the PubMed database using the key words "sepsis" and "biomarker" to identify clinical and experimental studies which evaluated a biomarker in sepsis.

RESULTS

The search retrieved 3370 references covering 178 different biomarkers.

CONCLUSIONS

Many biomarkers have been evaluated for use in sepsis. Most of the biomarkers had been tested clinically, primarily as prognostic markers in sepsis; relatively few have been used for diagnosis. None has sufficient specificity or sensitivity to be routinely employed in clinical practice. PCT and CRP have been most widely used, but even these have limited ability to distinguish sepsis from other inflammatory conditions or to predict outcome.

Matrix metalloproteinases and their inhibitors: promising novel biomarkers in severe sepsis?

The multicenter study conducted by Lorente and coworkers published in the previous issue of Critical Care demonstrates that matrix metalloproteinase (MMP)-9 and MMP-10 and their inhibitor tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) are promising novel biomarkers to predict severity and outcome of sepsis. In recent years MMPs have emerged as biomarkers in a variety of diseases, such as sepsis, coronary artery disease, cancer, heart failure, chronic lung disease and rheumatoid arthritis. MMPs constitute a family of proteinases that are expressed during developmental, physiological, and pathophysiological processes, for example as a response to infection. Excessive inflammation following infection may cause tissue damage, and MMPs are implicated in causing this immunopathology. The activity of MMPs is regulated by secretion of specific inhibitors (TIMPs). Studies using MMP inhibitors and MMP knockout mice indicate that MMPs play an essential role in infection and in the host response to infection. The measurement of MMP-9 and MMP-10 and their inhibitor TIMP-1 in the intensive care setting could be an attractive noninvasive tool for determination of outcome of septic patients.

Matrix metalloproteinase-9, -10, and tissue inhibitor of matrix metalloproteinases-1 blood levels as biomarkers of severity and mortality in sepsis

Introduction

Matrix metalloproteinases (MMPs) play a role in infectious diseases through extracellular matrix (ECM) degradation, which favors the migration of immune cells from the bloodstream to sites of inflammation. Although higher levels of MMP-9 and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) have been found in small series of patients with sepsis, MMP-10 levels have not been studied in this setting. The objective of this study was to determine the predictive value of MMP-9, MMP-10, and TIMP-1 on clinical severity and mortality in a large series of patients with severe sepsis.

Methods

This was a multicenter, observational, and prospective study carried out in six Spanish Intensive Care Units. We included 192 (125 surviving and 67 nonsurviving) patients with severe sepsis and 50 age- and sex-matched healthy controls in the study. Serum levels of MMP-9, MMP-10, TIMP-1, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-10 were measured in patients with severe sepsis at the time of diagnosis and in healthy controls.

Results

Sepsis patients had higher levels of MMP-10 and TIMP-1, higher MMP-10/TIMP-1 ratios, and lower MMP-9/TIMP-1 ratios than did healthy controls (P < 0.001). An association was found between MMP-9, MMP-10, TIMP-1, and MMP-9/TIMP-1 ratios and parameters of sepsis severity, assessed by the SOFA score, the APACHE-II score, lactic acid, platelet count, and markers of coagulopathy. Nonsurviving sepsis patients had lower levels of MMP-9 (P = 0.037), higher levels of TIMP-1 (P < 0.001), lower MMP-9/TIMP-1 ratio (P = 0.003), higher levels of IL-10 (P < 0.001), and lower TNF-α/IL-10 ratio than did surviving patients. An association was found between MMP-9, MMP-10, and TIMP-1 levels, and TNF-α and IL-10 levels. The risk of death in sepsis patients with TIMP-1 values greater than 531 ng/ml was 80% higher than that in patients with lower values (RR = 1.80; 95% CI = 1.13 to 2.87;P = 0.01; sensitivity = 0.73; specificity = 0.45).

Conclusions

The novel findings of our study on patients with severe sepsis (to our knowledge, the largest series reporting data about MMP levels in sepsis) are that reduced MMP-9/TIMP-1 ratios and increased MMP-10 levels may be of great pathophysiologic significance in terms of severity and mortality, and that TIMP-1 levels may represent a biomarker to predict the clinical outcome of patients with sepsis.

Matrix metalloproteinases as drug targets in infections caused by gram-negative bacteria and in septic shock

The mammalian immune system is optimized to cope effectively with the constant threat of pathogens. However, when the immune system overreacts, sepsis, severe sepsis, or septic shock can develop. Despite extensive research, these conditions remain the leading cause of death in intensive care units. The matrix metalloproteinases (MMPs) constitute a family of proteases that are expressed in developmental, physiological, and pathological processes and also in response to infections. Studies using MMP inhibitors and MMP knockout mice indicate that MMPs play essential roles in infection and in the host defense against infection. This review provides a brief introduction to some basic concepts of infections caused by gram-negative bacteria and reviews reports describing MMP expression and inhibition, as well as studies with MMP-deficient mice in models of infection caused by gram-negative bacteria and of septic shock. We discuss whether MMPs should be considered novel drug targets in infection and septic shock.

Collagen-related biomarkers in severe sepsis: a big stretch?

Biomedical scientists are aggressively investigating biomarkers of disease and injury. The rationale for identifying biomarkers during pathological states, such as severe sepsis, is to improve clinical prognostication and stratify therapeutic interventions for optimal recovery. An added benefit of biomarker studies is knowledge genesis on pathophysiological mechanisms, critical information that provides a basis for hypothesis-driven research. Unfortunately, biomarkers rarely alter our clinical approach in severe sepsis as they are often non-specific, lack adequate sensitivity and/or are difficult to measure and interpret accurately. Given the complexity and heterogeneity of severe sepsis, and the unique genetically derived susceptibilities of individuals, it is highly unlikely that one or even a handful of biomarkers will provide adequate biomedical information for clinical guidance. Thus, biomarkers will ultimately alter clinical decision making only once a panel of promising biomarkers is identified, maximizing sensitivity and specificity, and then adequately scrutinized with quantitative scoring methods over large populations of patients.

Elevated plasma MMP1 and MMP9 are associated with abdominal aortic aneurysm rupture

BACKGROUND

The role of matrix metalloproteinases (MMPs) in abdominal aortic aneurysm (AAA) formation is well established. However the changes in plasma MMP levels with AAA rupture have not been reported. The aim of this study was to determine circulating levels of MMPs in non-ruptured and ruptured AAA immediately prior to open repair.

METHODS

Concentrations of MMPs and their endogenous tissue inhibitors (TIMPs) were quantified using ELISA in pre-operative plasma samples from non-ruptured and ruptured AAA.

RESULTS

MMP1 and MMP9 were elevated in the plasma of ruptured AAA versus non-ruptured AAA. A four-fold elevation in pre-operative plasma MMP9 was associated with non-survival at 30 days from rupture surgery compared with those surviving for greater than 30 days.

CONCLUSION

In conclusion, these findings support the role of MMPs in AAA pathogenesis. Elevation of MMP9 was associated with ruptured aneurysm related 30-day mortality and may represent a survival indicator in this group.

Investigation of the molecular mechanisms preceding PDE4 inhibitor-induced vasculopathy in rats: tissue inhibitor of metalloproteinase 1, a potential predictive biomarker

Phosphodiesterase (PDE) 4 inhibitors are a class of drugs that can provide novel therapies for asthma and chronic obstructive pulmonary disease. Their development is frequently hampered by the induction of vascular toxicity in rat mesenteric tissue during preclinical studies. Whereas these vascular lesions in rats have been well characterized histologically, little is known about their pathogenesis and in turn, sensitive and specific biomarkers for preclinical and clinical monitoring do not exist. In order to investigate the early molecular mechanisms underlying vascular injury, time-course studies were performed by treating rats for 2-24 h with high doses of the PDE4 inhibitor CI-1044. Transcriptomics analyses in mesenteric tissue were performed using oligonucleotide microarray and real-time RT-PCR technologies and compared to histopathological observations. In addition, protein measurements were performed in serum samples to identify soluble biomarkers of vascular injury. Our results indicate that molecular alterations preceded the histological observations of inflammatory and necrotic lesions in mesenteric arteries. Some gene expression changes suggest that the development of the lesions could follow a primary modulation of the vascular tone in response to the pharmacological effect of the compound. Activation of genes coding for pro- and antioxidant enzymes, cytokines, adhesion molecules, and tissue inhibitor of metalloproteinase 1 (TIMP-1) indicates that biomechanical stimuli may contribute to vascular oxidant stress, inflammation, and tissue remodeling. TIMP-1 appeared to be an early and sensitive predictive biomarker of the inflammatory and the tissue remodeling components of PDE4 inhibitor-induced vascular injury.