Hospital acquired pneumonia with high-risk bacteria is associated with increased pulmonary matrix metalloproteinase activity

The Role of Matrix Metalloproteinase in Inflammation with a Focus on Infectious Diseases

Matrix metalloproteinases (MMPs) are involved in extracellular matrix remodeling through the degradation of extracellular matrix components and are also involved in the inflammatory response by regulating the pro-inflammatory cytokines TNF-α and IL-1β. Dysregulation in the inflammatory response and changes in the extracellular matrix by MMPs are related to the development of various diseases including lung and cardiovascular diseases. Therefore, numerous studies have been conducted to understand the role of MMPs in disease pathogenesis. MMPs are involved in the pathogenesis of infectious diseases through a dysregulation of the activity and expression of MMPs. In this review, we discuss the role of MMPs in infectious diseases and inflammatory responses. Furthermore, we present the potential of MMPs as therapeutic targets in infectious diseases.

The Yin and Yang of Pneumolysin During Pneumococcal Infection

Pneumolysin (PLY) is a pore-forming toxin produced by the human pathobiont Streptococcus pneumoniae, the major cause of pneumonia worldwide. PLY, a key pneumococcal virulence factor, can form transmembrane pores in host cells, disrupting plasma membrane integrity and deregulating cellular homeostasis. At lytic concentrations, PLY causes cell death. At sub-lytic concentrations, PLY triggers host cell survival pathways that cooperate to reseal the damaged plasma membrane and restore cell homeostasis. While PLY is generally considered a pivotal factor promoting S. pneumoniae colonization and survival, it is also a powerful trigger of the innate and adaptive host immune response against bacterial infection. The dichotomy of PLY as both a key bacterial virulence factor and a trigger for host immune modulation allows the toxin to display both "Yin" and "Yang" properties during infection, promoting disease by membrane perforation and activating inflammatory pathways, while also mitigating damage by triggering host cell repair and initiating anti-inflammatory responses. Due to its cytolytic activity and diverse immunomodulatory properties, PLY is integral to every stage of S. pneumoniae pathogenesis and may tip the balance towards either the pathogen or the host depending on the context of infection.

Establishment of a Risk Score Model for Early Prediction of Severe H1N1 Influenza

H1N1 is the most common subtype of influenza virus circulating worldwide and can cause severe disease in some populations. Early prediction and intervention for patients who develop severe influenza will greatly reduce their mortality. In this study, we conducted a comprehensive analysis of 180 PBMC samples from three published datasets from the GEO DataSets. Differentially expressed gene (DEG) analysis and weighted correlation network analysis (WGCNA) were performed to provide candidate DEGs for model building. Functional enrichment and CIBERSORT analyses were also performed to evaluate the differences in composition and function of PBMCs between patients with severe and mild disease. Finally, a risk score model was built using lasso regression analysis, with six genes (CX3CR1, KLRD1, MMP8, PRTN3, RETN and SCD) involved. The model performed moderately in the early identification of patients that develop severe H1N1 disease.

A functional polymorphism at the miR‑491‑5p binding site in the 3'‑untranslated region of the MMP‑9 gene increases the risk of developing ventilator‑associated pneumonia

Matrix metalloproteinase (MMP)‑9 is associated with the severity of ventilator‑associated pneumonia (VAP), while an rs1056629 SNP located in the 3'‑untranslated region (UTR) of MMP‑9 affects the microRNA (miRNA/miR)‑491‑mediated regulation of MMP‑9 expression. In the present study, the effect of rs1056629 on the development of VAP in patients with chronic obstructive pulmonary disease (COPD) was investigated. Patients with COPD were enrolled in the study and their genotypes of rs1056629 (CC, CA or AA) were determined. ELISA was used to analyze the levels of TNF‑α and IL‑6 in the monocytes of patients with COPD carrying differential genotypes of rs1056629. Reverse transcription‑quantitative PCR was carried out to evaluate the expression of miR‑491 and MMP‑9 mRNA in the different groups of patients with COPD. Luciferase assay was used to confirm the inhibitory role of miR‑491 in MMP‑9 expression. Western blot analysis was carried out to assess the expression of MMP‑9 protein in A549 and H1299 cells transfected with miR‑491 mimics. The risk and severity of VAP were significantly elevated in patients with COPD carrying the CC and AC genotypes of rs1056629. Although there was no difference in the expression of miR‑491 in patients carrying different genotypes of rs1056629, the expression levels of TNF‑α, IL‑6 and MMP‑9 were increased in patients with COPD carrying the CC and AC genotypes of rs1056629. The results of luciferase assay revealed that miR‑491 inhibited the expression of MMP‑9 through direct binding to the 3'UTR of MMP‑9. Transfection of miR‑491 mimics into A549 and H1299 cells markedly suppressed the expression of MMP‑9 in a concentration‑dependent manner. On the whole, the findings of the present study confirm that the CC and AC genotypes of rs1056629 increase the risk of developing VAP in patients with COPD by increasing the expression of MMP‑9.

Monocyte Chemoattractant Protein-1, a Possible Biomarker of Multiorgan Failure and Mortality in Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) leads to increased patients’ mortality and medical expenditure. Monocyte chemoattractant protein-1 (MCP-1) plays a role in the pathogenesis of lung inflammation and infection. Therefore, the plasma concentration of MCP-1 was assessed and correlated with the clinical course in VAP patients. This retrospective observational study recruited 45 healthy volunteers, 12 non-VAP subjects, and 30 VAP patients. The diagnostic criteria for VAP were based on the American Thoracic Society guidelines, and the level of plasma MCP-1 was determined by ELISA. Plasma MCP-1 concentration was significantly elevated in the acute stage in VAP patients when compared with the control (p < 0.0001) and non-VAP patient groups (p = 0.0006). Subsequently, it was remarkably decreased following antibiotic treatment. Moreover, plasma MCP-1 concentration was positively correlated with indices of pulmonary dysfunction, including the lung injury score (p = 0.02) and the oxygenation index (p = 0.02). When patients with VAP developed adult respiratory distress syndrome (ARDS), their plasma MCP-1 concentrations were significantly higher than those of patients who did not develop ARDS (p = 0.04). Moreover, plasma MCP-1 concentration was highly correlated with organ failure scores, including simplified acute physiology score II (SAPS II, p < 0.0001), sequential organ failure assessment score (SOFA, p < 0.0001), organ dysfunctions and/or infection (ODIN, p < 0.0001), predisposition, insult response and organ dysfunction (PIRO, p = 0.005), and immunodeficiency, blood pressure, multilobular infiltrates on chest radiograph, platelets and hospitalization 10 days before onset of VAP (IBMP-10, p = 0.004). Our results demonstrate that plasma MCP-1 is an excellent marker for recognizing VAP when the cut-off level is set to 347.18 ng/mL (area under the curve (AUC) = 0.936, 95% CI = 0.863–0.977). In conclusion, MCP-1 not only could be a biological marker related to pulmonary dysfunction, organ failure, and mortality in patients with VAP, but also could be used for early recognition of VAP.

Convergence in the Epidemiology and Pathogenesis of COPD and Pneumonia

Chronic obstructive pulmonary disease (COPD) is one of the main causes of human mortalities globally after heart disease and stroke. There is increasing evidence of an aetiological association between COPD and pneumonia, the leading infectious cause of death globally in children under 5 years. In this review, we discuss the known risk factors of COPD that are also shared with pneumonia including smoking, air pollution, age and immune suppression. We review how lung pathology linked to a previous history of pneumonia may heighten susceptibility to the development of COPD in later life. Furthermore, we examine how specific aspects of COPD immunology could contribute to the manifestation of pneumonia. Based on the available evidence, a convergent relationship is becoming apparent with respect to the pathogenesis of COPD and pneumonia. This has implications for the management of both diseases, and the development of new interventions.

Sustained-release synthetic biomarkers for monitoring thrombosis and inflammation using point-of-care compatible readouts

Postoperative infection and thromboembolism represent significant sources of morbidity and mortality but cannot be easily tracked after hospital discharge. Therefore, a molecular test that could be performed at home would significantly impact disease management. Our lab has previously developed intravenously delivered 'synthetic biomarkers' that respond to dysregulated proteases to produce a urinary signal. These assays, however, have been limited to chronic diseases or acute diseases initiated at the time of diagnostic administration. Here, we formulate a subcutaneously administered sustained release system by using small PEG scaffolds (<10 nm) to promote diffusion into the bloodstream over a day. We demonstrate the utility of a thrombin sensor to identify thrombosis and an MMP sensor to measure inflammation. Finally, we developed a companion paper ELISA using printed wax barriers with nanomolar sensitivity for urinary reporters for point-of-care detection. Our approach for subcutaneous delivery of nanosensors combined with urinary paper analysis may enable facile monitoring of at-risk patients.

Elevated Plasma Matrix Metalloproteinase-9 and Its Correlations with Severity of Disease in Patients with Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) increases patient mortality and medical expenditure, and a real-time and reliable method for the rapid diagnosis of VAP may help reduce fatal complications. Matrix metalloproteinases-9 (MMP-9) is considered significant in the pathogenesis of lung inflammation and infection. Therefore, we examined its relationship with the clinical course of VAP. This retrospective observational study recruited 30 healthy volunteers, 12 patients who used mechanical ventilation without the development of VAP (hereafter, patients without VAP), and 30 patients with a clinical diagnosis of VAP (hereafter, patients with VAP). The activity and level of plasma MMP-9 were determined through a gelatin zymography assay and ELISA. Our results report that both plasma MMP-9 activity and concentration were significantly elevated in the acute stage of patients with VAP when compared with control group and patients without VAP (p < 0.001). Subsequently, the plasma MMP-9 of patients with VAP decreased significantly after antibiotic treatment. Furthermore, plasma MMP-9 concentration was positively correlated with the clinical pulmonary infection score (r = 0.409, p = 0.007), WBCs (r = 0.620, p < 0.001), and neutrophils counts (r = 0.335, p = 0.035). In addition, plasma MMP-9 is an excellent tool for recognizing VAP when the cutoff level is set to 92.62 ng/mL (AUC = 0.863, 95% CI = 0.761 to 0.932). In conclusions, we concluded that MMP-9 levels play a role in the development of VAP and might have the potential to be applied in the development of VAP therapies.

Low levels of tissue inhibitor of metalloproteinase-2 at birth may be associated with subsequent development of bronchopulmonary dysplasia in preterm infants

Purpose

Bronchopulmonary dysplasia (BPD) is characterized by inflammation with proteolytic damage to the lung extracellular matrix. The results from previous studies are inconsistent regarding the role of proteinases and antiproteinases in the development of BPD. The aim of the present study was to investigate whether matrix metalloproteinase (MMP)-8, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-2, and TIMP-1 levels in the serum of preterm infants at birth are related to the development of BPD.

Methods

Serum was collected from 62 preterm infants at birth and analyzed for MMP-8, MMP-9, TIMP-2, and TIMP-1 by using enzyme-linked immunosorbent assay. MMPs and TIMPs were compared in BPD (n=24) and no BPD groups (n=38). Clinical predictors of BPD (sex, birth weight, gestational age, etc.) were assessed for both groups. The association between predictors and outcome, BPD, was assessed by using multivariate logistic regression.

Results

Sex, birth weight, and mean gestational age were similar between the groups. BPD preterm infants had significantly lower TIMP-2 levels at birth compared with no BPD preterm infants (138.1±23.0 ng/mL vs. 171.8±44.1 ng/mL, P=0.027). No significant difference was observed in MMP-8, MMP-9, and TIMP-1 levels between the two groups. Multivariate logistic regression analysis indicated that the TIMP-2 levels were predictive of BPD after adjusting for sex, birth weight, gestational age, proteinuric preeclampsia, and intraventricular hemorrhage (β=-0.063, P=0.041).

Conclusion

Low TIMP-2 serum levels at birth may be associated with the subsequent development of BPD in preterm infants.

MMP-8 genotypes influence the inflammatory response in human endotoxemia

Clinical studies have reported associations between MMP-8 genotypes and clinical outcomes without exploring underlying mechanisms. This study aims to understand the influence of the rs1940475 SNP on downstream chemokine and cytokine response in human endotoxemia. Rs1940475 was genotyped in 44 healthy Caucasian males, who were challenged with an intravenous bolus of 2 ng/kg lipopolysaccharide (LPS). Plasma levels of tumor necrosis factor (TNF), interleukin (IL)-6, IL-8, and macrophage inflammatory protein (MIP)-1α were measured at baseline and 2, 4, 6, and 24 h after LPS infusion with high-sensitivity enzyme immunoassays. Peak TNF levels at 2 h after LPS infusion were significantly higher in subjects with AA genotype compared to subjects with AG or GG genotypes (185 pg/mL [IQR, 154–234] vs. 94 pg/mL [IQR, 65–125] vs. 107 pg/mL [IQR, 80–241], respectively; p = 0.03 between groups). Peak IL-6 levels were trend-wise higher in subjects with AA genotype compared to those with AG or GG genotypes (566 pg/mL [IQR, 294–644] vs. 278 pg/mL [IQR, 184–539] and 329 pg/mL [IQR, 240–492], respectively; p = 0.15 between groups). In contrast, peak MIP-1α at 2 h was highest in GG genotype carriers compared to those with AG or AA genotypes (602 pg/mL [IQR, 449–727] vs. 389 pg/mL [IQR, 375–490] and 510 pg/mL [425–813], respectively; p < 0.03 between groups). AA genotype carriers had highest peak TNF and IL-6 levels after LPS challenge, whereas peak MIP-1α levels were highest in GG carriers. This indicates that the rs1940475 SNP modifies the host response to inflammatory stimuli, which may in part explain previously shown associations with clinical outcomes.

Recognition of Streptococcus pneumoniae and muramyl dipeptide by NOD2 results in potent induction of MMP-9, which can be controlled by lipopolysaccharide stimulation

Matrix metallopeptidase 9 (MMP-9) is a protease involved in the degradation of extracellular matrix collagen. Evidence suggests that MMP-9 is involved in pathogenesis during Streptococcus pneumoniae infection. However, not much is known about the induction of MMP-9 and the regulatory processes involved. We show here that the Gram-positive bacteria used in this study induced large amounts of MMP-9, in contrast to the Gram-negative bacteria that were used. An important pathogen-associated molecular pattern (PAMP) for Gram-positive bacteria is muramyl dipeptide (MDP). MDP is a very potent inducer of MMP-9 and showed a dose-dependent MMP-9 induction. Experiments using peripheral blood mononuclear cells (PBMCs) from Crohn's disease patients with nonfunctional NOD2 showed that MMP-9 induction by Streptococcus pneumoniae and MDP is NOD2 dependent. Increasing amounts of lipopolysaccharide (LPS), an important PAMP for Gram-negative bacteria, resulted in decreasing amounts of MMP-9. Moreover, the induction of MMP-9 by MDP could be counteracted by simultaneously adding LPS. The inhibition of MMP-9 expression by LPS was found to be regulated posttranscriptionally, independently of tissue inhibitor of metalloproteinase 1 (TIMP-1), an endogenous inhibitor of MMP-9. Collectively, these data show that Streptococcus pneumoniae is able to induce large amounts of MMP-9. These high MMP-9 levels are potentially involved in Streptococcus pneumoniae pathogenesis.

Matrix metalloproteinases in pneumonia

Pneumonia is a worldwide infectious disease that is associated with significant morbidity and mortality and is the most common fatal infection acquired in hospitals. Despite advances in preventive strategies, such as antibiotic therapies and intensive care, the mortality rate still requires substantial improvement. Matrix metalloproteinases (MMPs) are a large family of zinc-dependent endopeptidases, which are known as the major enzymes responsible for the proteolytic degradation of proteinaceous components of the extracellular matrix (ECM). Although the main function of MMPs is the removal of the ECM during tissue resorption and progression of various diseases, MMPs also interact with multiple cytokines, participating in the pathology of infection and inflammation. This review presents a schematic overview of the different MMPs expressed in pneumonia. MMPs are key factors in the pathogenesis of various types of pneumonia, such as community-acquired pneumonia, hospital-acquired pneumonia, and ventilator-associated pneumonia. Here, we review the pathological roles of various MMPs in pneumonia.

Ventilator-associated pneumonia is characterized by excessive release of neutrophil proteases in the lung

BACKGROUND

Ventilator-associated pneumonia (VAP) is characterized by neutrophils infiltrating the alveolar space. VAP is associated with high mortality, and accurate diagnosis remains difficult. We hypothesized that proteolytic enzymes from neutrophils would be significantly increased and locally produced inhibitors of human neutrophil elastase (HNE) would be decreased in BAL fluid (BALF) from patients with confirmed VAP. We postulated that in suspected VAP, neutrophil proteases in BALF may help identify "true" VAP.

METHODS

BAL was performed in 55 patients with suspected VAP and in 18 control subjects. Isolation of a pathogen(s) at > 10⁴ colony-forming units/mL of BALF dichotomized patients into VAP (n = 12) and non-VAP (n = 43) groups. Matrix metalloproteinases (MMPs), HNE, inhibitors of HNE, and tissue inhibitors of matrix metalloproteinases (TIMPs) were quantified. Plasminogen activator (PA) activity was estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and zymography.

RESULTS

Neutrophil-derived proteases HNE, MMP-8, and MMP-9 were significantly increased in cell-free BALF from patients with VAP as compared with those without VAP (median values: HNE, 2,708 ng/mL vs 294 ng/mL, P < .01; MMP-8, 184 ng/mL vs 5 ng/mL, P < .01; MMP-9, 310 ng/mL vs 11 ng/mL, P < .01). HNE activity was also significantly increased in VAP (0.45 vs 0.01 arbitrary units; P < .05). In contrast, no significant differences were observed for protease inhibitors, TIMPs, or PAs. HNE in BALF, at a cutoff of 670 ng/mL, identified VAP with a sensitivity of 93% and specificity of 79%.

CONCLUSIONS

Neutrophil proteases are significantly elevated in the alveolar space in VAP and may contribute to pathogenesis. Neutrophil proteases appear to have potential in suspected VAP for distinguishing true cases from "non-VAP" cases.

Mycoplasma pneumoniae in adult community-acquired pneumonia increases matrix metalloproteinase-9 serum level and induces its gene expression in peripheral blood mononuclear cells

Background

The objective of this study was to assess the concentration of metalloproteinase-2 (MMP-2) and metalloproteinase-9 (MMP-9) in peripheral circulation and their mRNA expression in peripheral blood mononuclear cells (PBMCs) in patients with CAP caused by M. pneumoniae.

Material/Methods

We prospectively analyzed MMPs in 40 hospitalized patients with M. pneumoniae CAP on admission, and in the convalescent phase. Twenty healthy men were used as controls. Quantitative real-time PCR and ELISA tests were used.

Results

MMP-9 mRNA expression in PBMCs was increased in the acute phase of illness compared to the control group as well as in convalescent phase in which case it was statistically significant (Mann-Whitney; p=0.028). The same was found for MMP-9 plasma levels (Mann-Whitney test; p<0.001; p=0.001). Circulating MMP-2 concentration in acute patients was significantly lower than in the control group and convalescent phase (Mann-Whitney test; p=0.012; p=0.001), while no MMP-2 mRNA expression was found in PBMCs. The plasma level of MMP-9 correlated with leukocyte count in peripheral circulation (r=0.67, p<0.001).

Conclusions

We conclude that M. pneumoniae in adult CAP induces activity of MMP-9 in peripheral blood circulation.

Use of MMP-8 and MMP-9 to assess disease severity in children with viral lower respiratory tract infections

Matrix metalloproteinases (MMPs) play an important role in respiratory inflammatory diseases, such as asthma and chronic obstructive pulmonary disease. It was hypothesized that MMP-8 and MMP-9 may function as biological markers to assess disease severity in viral lower respiratory tract infections in children. MMP-8 and MMP-9 mRNA expression levels in peripheral blood mononuclear cells (PBMCs) and granulocytes obtained in both the acute and recovery phase from 153 children with mild, moderate, and severe viral lower respiratory tract infections were determined using real-time PCR. In addition, MMP-8 and MMP-9 concentrations in blood and nasopharyngeal specimens were determined during acute mild, moderate, and severe infection, and after recovery using ELISA. Furthermore, PBMCs and neutrophils obtained from healthy volunteers were stimulated with RSV, LPS (TLR4 agonist), and Pam3Cys (TLR2 agonist) in vitro. Disease severity of viral lower respiratory tract infections in children is associated with increased expression levels of the MMP-8 and MMP-9 genes in both PBMCs and granulocytes. On the contrary, in vitro experiments showed that MMP-8 and MMP-9 mRNA and protein expression in PBMCs and granulocytes is not induced by stimulation with RSV, the most frequent detected virus in young children with viral lower respiratory tract infections. These data indicate that expression levels of the MMP-8 and MMP-9 genes in both PBMCs and neutrophils are associated with viral lower respiratory tract infections disease severity. These observations justify future validation in independent prospective study cohorts of the usefulness of MMP-8 and MMP-9 as potential markers for disease severity in viral respiratory infections.

Association of circulating levels of MMP-8 with mortality from respiratory disease in patients with rheumatoid arthritis

Introduction

Matrix metalloproteinases (MMPs) are implicated in the destruction of the joint and have been shown to be strongly associated with inflammation in rheumatoid arthritis (RA). Circulating MMPs have also been associated with cardiovascular disease in the general population, and are predictive of cardiovascular mortality. The purpose of the present study was to determine whether circulating levels of MMPs are predictive of mortality in RA.

Methods

A multiplex suspension array system (Luminex^®) was used to measure levels of MMPs (1, 2, 3, 8 and 9) in sera taken at recruitment of RA patients (n = 487) in a study of factors associated with mortality in RA. Patients were tracked on the National Health Service Central Register for notification of death, and the relationship between baseline MMP levels and mortality was analysed using Cox proportional hazards regression analysis.

Results

At the time of follow-up, 204/486 patients had died, of which 94 (46.1%) had died of circulatory diseases, 49 of malignancy (24.0%), and 42 (20.6%) of respiratory diseases. In a stepwise analysis which included all MMPs, only MMP-8 was significantly associated with all cause mortality (P = 0.0007, 0.6% hazard ratio increase per ng/ml). No association was found between MMP levels and mortality due to circulatory disease or malignancy. However MMP-8 levels were strongly associated with mortality due to respiratory disease (P < 0.0001, 1.3% hazard ratio increase per ng/ml). The association with respiratory disease related mortality remained highly significant in multivariate models which included smoking as well as markers of severity and disease activity such as rheumatoid factor, nodular disease, and C-reactive protein (CRP).

Conclusions

The serum level of MMP-8 is a strong predictor of mortality in RA, especially that due to respiratory disease. This finding is consistent with increased activation of neutrophils in RA and identifies serum MMP-8 as a useful marker for increased risk of premature death.

Enhanced exhalation of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in patients with COPD exacerbation: a prospective study

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) and its inhibitor tissue inhibitor of metalloproteinase-1 (TIMP-1) are involved in the pathogenesis of airway inflammation in patients with chronic obstructive pulmonary disease (COPD). However, no study so far has addressed their value as noninvasive biomarkers of airways inflammation.

OBJECTIVE

To evaluate MMP-9 and TIMP-1 concentrations in the exhaled breath condensate (EBC) of patients with stable COPD and also during the exacerbation episode.

METHODS

EBC and serum samples were collected in 17 stable-phase COPD patients who were current smokers as well as during their first exacerbation episode, and in 22 asymptomatic smokers. EBC and serum levels of MMP-9 and TIMP-1 were measured with ELISA kit.

RESULTS

Mean EBC MMP-9 and TIMP-1 levels were higher in patients with stable COPD than in asymptomatic smokers. Exacerbation of COPD increased 2-fold the exhalation of MMP-9 (18.5 ± 10.1 ng/ml vs. 8.9 ± 6.2 ng/ml, p = 0.01) and TIMP-1 (to 41.1 ± 20.4 ng/ml vs. 16.4 ± 6.8 ng/ml, p < 0.001). Both, MMP-9 and TIMP-1 in EBC correlated negatively with FEV(1) (% predicted) at baseline (r = -0.78, p < 0.001 and r = -0.73, p < 0.001) and during the exacerbation episode (r = -0.57, p = 0.02 and r = -0.65, p = 0.005). Similar negative correlations were noted with FVC (% predicted), except for MMP-9 in EBC at exacerbation. Exhaled MMP-9 and TIMP-1 did not correlate with serum concentrations in COPD patients, either at baseline or during exacerbation.

CONCLUSION

Exhaled MMP-9 and TIMP-1 increased during COPD exacerbation and was negatively correlated with spirometric variables, which suggests the usefulness of their measurement in EBC for the monitoring of airways inflammation. However, to better assess their diagnostic or prognostic value larger studies are necessary.

Expression levels of matrix metalloproteinase (MMP)-9 and its specific inhibitor TIMP-1, in septic and aseptic arthritis of the knee

PURPOSE

In cases of septic knee arthritis, there is excess of matrix metalloproteinases (MMPs) over tissue inhibitors of metalloproteinases (TIMPs), due to enhanced expression and activation that are induced by bacteria in comparison with rheumatic or degenerative arthritis. The aim of this study was to explore the expression levels of synovial gelatinase MMP-9 and its specific inhibitor TIMP-1 in septic and aseptic arthritis and their potential use as additional aids to clinical investigation.

METHODS

Gelatin zymography and western blot analysis were applied in effusions from knees of the patients with septic (SA-10 patients), rheumatic (RA-10 patients) and osteoarthritis (OA-10 patients).

RESULTS

Zymographic analysis revealed that all samples contained latent MMP-2 activity, albeit activated MMP-2 appeared in more of the septic than aseptic effusions. MMP-9 was not detected in osteoarthritic synovial fluid samples. Only trace amounts of MMP-9 activity were detected in 4 of 10 patients with RA, whereas higher MMP-9 levels were evident in all samples from SA (P = 0.0241). In immunoblotting assays, samples from SA showed significantly higher levels of MMP-9 compared with samples from RA (P = 0.0052), confirming zymographic results. Although no significant difference in TIMP-1 levels was observed, the estimated MMP-9/TIMP-1 ratio of septic effusions was significantly higher compared with aseptic ones (P = 0.0029).

CONCLUSIONS

The data presented suggest enhanced expression and activation of MMP-9 in septic native knee arthritis compared with aseptic. The presence of high levels of MMP-9 with concomitantly increased MMP-9/TIMP-1 ratio and activated gelatinases in effusions, independent of neutrophilic counts, may be indicative for infection.

Matrix metalloproteinase8 has a central role in inflammatory disorders and cancer progression

The predominant role of matrix metalloproteinase 8 in extracellular matrix turnover, modulation of inflammatory responses and other physiological processes is well documented. Several recent studies highlight the involvement of MMP8 in a wide range of pathologies. This review will shed light on the putative role of MMP8 as a drug target or disease marker in some inflammatory disorders and in cancer progression.

Staphylococcus Aureus Increases Cytokine and Matrix Metalloproteinase Expression in Nasal Mucosae of Patients with Chronic Rhinosinusitis and Nasal Polyps

Background

Staphylococcus aureus is a common bacterial pathogen associated with chronic rhinosinusitis with/without nasal polyps (CRSw/sNP). We investigated the effect of S. aureus on the secretion of eotaxin, interleukin (IL)-5, IL-8, IL-13, matrix metalloproteinase (MMP) 2, MMP-9, and tissue inhibitor of MMP (TIMP) 1 in nasal mucosae from CRSwNP patients to assess the roles of these materials in NP pathogenesis.

Methods

We infected organ cultures of NP and inferior turbinate (IT) mucosae taken from patients with CRSwNP with S. aureus ATCC 25923 for 24 hours and incubated the cultures for an additional 48 hours at 37°C. S. aureus infection and staphylococcal enterotoxins were confirmed by real-time polymerase chain reaction. Eotaxin, IL-5, IL-8, IL-13, MMP-2, MMP-9, and TIMP-1 protein levels were measured by ELISA.

Results

S. aureus infection significantly increased the concentrations of eotaxin, IL-5, IL-8, and IL-13 in the IT and NP groups (p < 0.01 for all comparisons). S. aureus infection also significantly increased the concentrations of MMP-2, MMP-9, and TIMP-1 in both groups (p < 0.001 for all comparisons). After S. aureus infection, the relative increases in eotaxin (6.42 versus 3.56), IL-5 (15.29 versus 8.89), MMP-2 (1.95 versus 1.58), MMP-9 (2.34 versus 1.95), and TIMP-1 (1.45 versus 1.31) were greater in the NP group than in the IT group.

Conclusion

S. aureus infection enhances the secretion of cytokines, MMP-2, MMP-9, and TIMP-1 by both NPs and IT mucosae from patients with CRSwNP. S. aureus may play an important role in the pathogenesis of NP via tissue remodeling as well as eosinophilic inflammation.

Gene expression changes associated with resistance to intravenous corticosteroid therapy in children with severe ulcerative colitis

BACKGROUND AND AIMS

Microarray analysis of RNA expression allows gross examination of pathways operative in inflammation. We aimed to determine whether genes expressed in whole blood early following initiation of intravenous corticosteroid treatment can be associated with response.

METHODS

From a prospectively accrued cohort of 128 pediatric patients hospitalized for intravenous corticosteroid treatment of severe UC, we selected for analysis 20 corticosteroid responsive (hospital discharge or PUCAI ≤45 by day 5) and 20 corticosteroid resistant patients (need for second line medical therapy or colectomy, or PUCAI >45 by day 5). Total RNA was extracted from blood samples collected on day 3 of intravenous corticosteroid therapy. The eluted transcriptomes were quantified on Affymetrix Human Gene 1.0 ST arrays. The data was analysed by the local-pooled error method for discovery of differential gene expression and false discovery rate correction was applied to adjust for multiple comparisons.

RESULTS

A total of 41 genes differentially expressed between responders and non-responders were detected with statistical significance. Two of these genes, CEACAM1 and MMP8, possibly inhibited by methylprednisolone through IL8, were both found to be over-expressed in non-responsive patients. ABCC4 (MRP4) as a member of the multi-drug resistance superfamily was a novel candidate gene for corticosteroid resistance. The expression pattern of a cluster of 10 genes selected from the 41 significant hits were able to classify the patients with 80% sensitivity and 80% specificity.

CONCLUSIONS

Elevated expression of several genes involved in inflammatory pathways was associated with resistance to intravenous corticosteroid therapy early in the course of treatment. Gene expression profiles may be useful to classify resistance to intravenous corticosteroids in children with severe UC and assist with clinical management decisions.