Matrix metalloproteinase-9 promotes neutrophil migration and alveolar capillary leakage in pancreatitis-associated lung injury in the rat

Influence of early neutrophil depletion on MMPs/TIMP-1 balance in bleomycin-induced lung fibrosis

Pulmonary fibrosis is characterized by excessive deposition of extracellular matrix in interstitium resulting in respiratory failure associated with inflammation showing mainly neutrophil (PMN) recruitment. The turn over of extracellular matrix is partially regulated by proteases such as metalloproteinases (MMPs) and their inhibitors (TIMPs). We investigated the impact of PMN depletion on the MMP/TIMP-1 imbalance and the development of fibrosis in mice induced by bleomycin (0.3 mg/mouse). Administration of 200 microL of rabbit anti-mouse PMN antibody i.p. blunted the neutrophil influx detected in BAL and in whole blood one day after bleomycin administration. At day(14), hydroxyproline content was increased both in anti-PMN treated and control mice, without any difference between groups. At day one, bleomycin elicited a raise in pro-MMP-9 level in BAL that was significantly attenuated in anti-PMN depleted mice, whereas TIMP-1 and MMP-2 release were similar in both groups at day(1) and day(14). Higher RNA levels were observed in PMN-treated mice at day(1) for MMP-9 and MMP-2 and at day(14) for MMP-2 only. At day(14), bleomycin elicited a raise of TIMP-1 protein and RNA levels regardless of anti-PMN treatment, whereas MMP-9 returned to basal level. Bleomycin enhanced MMP-8 level in BAL at day(14) only for the control group. The amount of MMP-8 was more important in BAL from anti-PMN treated mice than in control mice at day(1) and day(14). PMN-depletion and the associated modifications in pro-MMP-9/TIMP-1 imbalance in lung during the early inflammatory phase do not alter susceptibility to bleomycin-induced pulmonary fibrosis.

Axial stretch: A novel mechanism of the lower esophageal sphincter relaxation

Swallow and esophageal distension-induced relaxations of the lower esophageal sphincter (LES) are associated with an orad movement of the LES because of a concurrent esophageal longitudinal muscle contraction. We hypothesized that the esophageal longitudinal muscle contraction induces a cranially directed mechanical stretch on the LES and therefore studied the effects of a mechanical stretch on the LES pressure. In adult opossums, a silicon tube was placed via mouth into the esophagus and laparotomy was performed. Two needles with silk sutures were passed, 90 degrees apart, through the esophageal walls and silicon tube, 2 cm above the LES. The tube was withdrawn, and one end of each of the four sutures was anchored to the esophageal wall and the other end exited through the mouth to exert graded cranially directed stretch on the LES by using pulley and weights. A cranially directed stretch caused LES relaxation, and with the cessation of stretch there was recovery of the LES pressure. The degree an d duration of LES relaxation increased with the weight and the duration of stretch, respectively. The mean LES relaxation in all animals was 77.7 +/- 4.7%. The required weight to induce maximal LES relaxation differed in animals (714 +/- 348 g). N(G)-nitro-L-arginine, a nitric oxide inhibitor, blocked the axial stretch-induced LES relaxation almost completely (from 78 to 19%). Our data support the presence of an axial stretch-activated inhibitory mechanism in the LES. The role of axial stretch in the LES relaxation induced by swallow and esophageal distension requires further investigation.

Attenuation of dextran sodium sulphate induced colitis in matrix metalloproteinase-9 deficient mice

AIM: To study whether matrix metalloproteinase-9 (MMP-9) is a key factor in epithelial damage in the dextran sodium sulphate (DSS) model of colitis in mice.

METHODS: MMP-9-deficient and wild-type (wt) mice were given 5% DSS in drinking water for 5 d followed by recovery up to 7 d. On d 5 and 12 after induction of colitis, gelatinases, MMP-2 and MMP-9, were measured in homogenates of colonic tissue by zymography and Western blot, whereas tissue inhibitor of metalloproteinases (TIMPs) were measured by reverse zymography. The gelatinolytic activity was also determined in supernatants of polymorphonuclear leukocytes (PMN) isolated from mice blood. Moreover, intestinal epithelial cells were stimulated with TNF-α to study whether these cells were able to produce MMPs. Finally, colonic mucosal lesions were measured by microscopic examination.

RESULTS: On d 5 of colitis, the activity of MMP-9 was increased in homogenates of colonic tissues (0.24 ± 0.1 vs 21.3 ± 6.4, P < 0.05) and PMN from peripheral blood in wt (0.5 ± 0.1 vs 10.4 ± 0.7, P < 0.05), but not in MMP-9-deficient animals. The MMP-9 activity was also up-regulated by TNF-α in epithelial intestinal cells (2.5 ± 0.5 vs 14.7 ± 3.0, P < 0.05). Although colitis also led to increase of TIMP-1 activity, the MMP-9/TIMP-1 balance remained elevated. Finally, in the MMP-9-deficient colitic mice both the extent and severity of intestinal epithelial injury were significantly attenuated when compared with wt mice.

CONCLUSION: We conclude that DSS induced colitis is markedly attenuated in animals lacking MMP-9. This suggests that intestinal injury induced by DSS is modulated by MMP-9 and that inhibition of this gelatinase may reduce inflammation.

DOES MATRIX METALLOPROTEINASE ACTIVITY PREDICT SEVERITY OF ACUTE PANCREATITIS?

BACKGROUND

Matrix metalloproteinases (MMP) modulate end-organ complications of acute pancreatitis, but the correlation between increased MMP production and histological severity of disease remains unclear. We examined the role of MMP and pancreas histology on experimental acute pancreatitis.

METHODS

Forty male Wistar albino rats were subjected to cerulein-induced pancreatitis (8, 16, 24 and 32 h groups) or sham treatment. The animals were killed at different time points and pancreatic tissues were harvested to assess MMP (1, 2 and 9) activity and inflammatory changes.

RESULTS

Compared with other groups, 8 h group had decreased tissue MMP-1 concentrations. MMP-9 concentrations were lower in 24-h and 32-h groups, as were histological severity scores. MMP-2 activity did not differ among groups. Pancreatitis was prominent in 8-h, 16-h and 24-h groups by means of histology.

CONCLUSION

Induction of pancreatitis by cerulein altered pancreatic MMP levels in the early phase of inflammation. Inhibition of MMP-2 and MMP-9 paralleled histological scores. Therefore, MMP may have a predictive value to assess histological severity.

Cell-surface association between matrix metalloproteinases and integrins: role of the complexes in leukocyte migration and cancer progression

Leukocyte motility is known to be dependent on both β2-integrins and matrix metalloproteinases MMP-2/-9 or gelatinases, which mediate leukocyte adhesion and the proteolysis needed for invasion, respectively. Gelatinases not only play an important role in cell migration, tissue remodeling, and angiogenesis during development, but are also involved in the progression and invasiveness of many cancers, including leukemias. The concept that MMPs associate with integrins, as well as their importance in some physiologic and pathologic conditions, has been advanced previously but has not been examined on leukocytes. This review will examine mainly the function of the MMP-integrin complexes in normal leukocyte migration and the effect of integrin and broad-spectrum MMP inhibitors in tumor progression.

Disruption of tissue plasminogen activator gene reduces macrophage migration

Tissue plasminogen activator (tPA) is an essential component of the proteolytic cascade that lyses blood clots. Various studies also suggest that tPA plays important roles in peripheral nerve regeneration. Here we show that disruption of tPA gene reduces macrophage migration after sciatic nerve injury in mice. Moreover, lack of tPA activity attenuates migrating ability of macrophages and affects MMP-9 expression and activity in macrophages in vitro. Addition of ethylenediaminetetraacetic acid (EDTA), which inhibits MMPs, abolished the differences of migration ability of macrophages between tPA(+/+) and tPA(-/-) mice. Axonal regeneration is correlated with the increase of macrophage migration, suggesting that tPA may help create a beneficial environment for axonal regeneration through promoting macrophage infiltration. This study shows that tPA may play a role in nerve regeneration through regulating the migration ability of macrophages. This function of tPA may depend on, at least in part, upregulating MMP-9 expression and activity in macrophages.

Human Mast Cell-Derived Gelatinase B (Matrix Metalloproteinase-9) Is Regulated by Inflammatory Cytokines: Role in Cell Migration

Mast cells are key effectors in the pathogenesis of inflammatory and tissue destructive diseases such as rheumatoid arthritis (RA). These cells contain specialized secretory granules loaded with bioactive molecules including cytokines, growth factors, and proteases that are released upon activation. This study investigated the regulation of matrix metalloproteinase MMP-9 (gelatinase B) in human mast cells by cytokines that are known to be involved in the pathogenesis of RA. Immunohistochemical staining of synovial tissue showed abundant expression of MMP-9 by synovial tissue mast cells in patients with RA but not in normal controls. The expression, activity, and production of MMP-9 in mast cells was confirmed by RT-PCR, zymography, and Western blotting using cord blood-derived human mast cells (CB-HMC). Treatment of CB-HMC with TNF-alpha significantly increased the expression of MMP-9 mRNA and up-regulated the activity of MMP-9 in a time- and dose-dependent manner. By contrast, IFN-gamma inhibited MMP-9 mRNA and protein expression. The cytokine-mediated regulation of MMP-9 was also apparent in the human mast cell line (HMC-1) and in mouse bone marrow-derived mast cells. Furthermore, TNF-alpha significantly increased the invasiveness of CB-HMC across Matrigel-coated membranes while the addition of IFN-gamma, rTIMP-1, or pharmacological MMP inhibitors significantly reduced this process. These observations suggest that MMP-9 is not a stored product in mast cells but these cells are capable of producing this enzyme under inflammatory conditions that may facilitate the migration of mast cell progenitors to sites of inflammation and may also contribute to local tissue damage.

Matrix metalloproteinases and tumor metastasis

Functions of individual matrix metalloproteinases (MMPs) differentially expressed by tumor cells and stromal cells, are finely regulated by their spatial as well as temporal interactions with distinct cellular and extracellular components of the tumor microenvironment and also distant pre-metastatic sites. Certain aspects of MMP involvement in tumor metastasis such as tumor-induced angiogenesis, tumor invasion, and establishment of metastatic foci at the secondary site, have received extensive attention that resulted in an overwhelming amount of experimental and observational data in favor of critical roles of MMPs in these processes. In particular, dependency of tumor angiogenesis on the activity of MMPs, especially that of MMP-9, renders this step possibly the most effective target of synthetic MMP inhibitors. MMP functioning in other stages of metastasis, including the escape of individual tumor cells from the primary tumor, their intravasation, survival in circulation, and extravasation at the secondary site, have not yet received enough consideration, resulting in insufficient or controversial data. The major pieces of evidence that are most compelling and clearly determine the role and involvement of MMPs in the metastatic cascade are provided by molecular genetic studies employing knock-out or transgenic animals and tumor cell lines, modified to overexpress or downregulate a specific MMP. Findings from all of these studies implicate different functional mechanisms for both tumor and stromal MMPs during distinct steps of the metastatic cascade and indicate that MMPs can exhibit pro-metastatic as well as anti-metastatic roles depending on their nature and the experimental setting. This dual function of individual MMPs in metastasis has become a major focus of this review.

Captopril, an Angiotensin-converting enzyme inhibitor, attenuates the severity of acute pancreatitis in rats by reducing expression of matrix metalloproteinase 9

It has been reported that matrix metalloproteinase 9 (MMP-9) disrupts basement membrane and increases vascular permeability. MMP-9 therefore might participate in the pathogenesis of severe acute pancreatitis (SAP). Captopril, an angiotensin-converting enzyme inhibitor, could reduce MMP-9 expression. However, the effect of captopril on the outcome of SAP is not ascertained. The aim of this study was to determine whether captopril attenuates the severity of SAP by reducing MMP-9 expression. Thirty Sprague-Dawley rats were randomly divided into 3 groups (n = 10 for each). Rats were given intraperitoneal injection of saline (SAP group) or captopril (4 mg/kg) (treated group), and then given retrograde infusion of 5% sodium taurocholate (1.5 ml/kg) into the pancreatic duct under laparotomy to induce SAP. One group of rats, injected with saline, underwent only sham operation (Control). Experimental samples were collected at 24 hrs after the induction of SAP or sham operation. Various markers of severity of SAP, such as serum levels of amylase and trypsinogen activation peptide and the vascular permeability, were increased in rats with SAP, but were significantly decreased in captopril-treated rats (p < 0.01). Likewise, the serum MMP-9 levels and expression levels of pancreatic tissue MMP-9 were significantly higher in rats with SAP than those in captopril-treated rats and control rats (p < 0.01 for both parameters), but showed no difference between captopril-treated and control rats. These results suggest that captopril may attenuate vascular permeability by reducing MMP-9 expression in SAP, thereby ameliorating severity of the disease. The use of captopril might become a new therapeutic agent for SAP.

Salicylate enhances rat gastric gelatinase activity

BACKGROUND

Increased matrix metalloproteinase (MMP) activity is associated with tissue injury in some organs. Their role in gut injury remains to be fully elucidated. We recently demonstrated that increased MMP-2 activity participated in lipopolysaccharide (LPS)-induced gastric injury. Thus we hypothesized that MMPs may play a role in other models of gastric injury.

MATERIALS AND METHODS

The effect of L-NAME (10 mg/kg IP) or salicylate (100 mg/kg IP) on gastric injury from 20% ethanol was evaluated in an anesthetized model of gastric injury. In a separate experiment, gastric metalloproteinase activity was assessed after salicylate or L-NAME administration. Rats were given either L-NAME (10 mg/kg), salicylate (100 mg/kg), or saline IP and sacrificed after 6 hours. Gastric mucosa was harvested and portions of the glandular stomach snap frozen for gelatin and in situ zymography as indices of MMP activity. Subsequently the effect of MMP inhibition on macroscopic gastric injury from salicylate and a dilute luminal irritant was determined.

RESULTS

Both L-NAME and salicylate significantly increased gastric injury from 20% ethanol versus saline controls. Salicylate treatment significantly increased gelatinase activity as determined by in situ zymography and gelatin zymography while L-NAME did not. MMP inhibition ameliorated macroscopic gastric injury secondary to salicylate and a dilute luminal irritant.

CONCLUSIONS

This is the first study to report that MMP activity increases in the stomach following salicylate treatment. These data suggest that MMPs may play a role in the ability of salicylate to exacerbate gastric injury from irritants, but likely do not play a role in mediating the deleterious effects of L-NAME.

Expression of Matrix Metalloproteinases 2, 7 and 9, and Their Tissue Inhibitors 1 and 2, in Developing Rabbit Tracheae

BACKGROUND

Structural changes in the developing conducting airway impact the rigidity of the airway, altering the airway's ability to sustain its shape during ventilation. The developmental changes in airway compliance oppose the changes in compliance of the developing lung; thus the expression profiles of matrix modeling proteins likely are also opposite in these developing organs.

OBJECTIVES

To determine the profiles of matrix metalloproteinases (MMPs) -2, -7, and -9 and tissue inhibitors (TIMPs) -1 and -2 in the developing trachea and test the hypothesis these profiles would contrast those previously reported for the lung.

METHODS

Rabbits tracheae were harvested at 21 days of gestation, 3 and 17 days postgestation and at adulthood. Tissue homogenates were analyzed by substrate zymography for the activity of MMPs, and reverse zymography for TIMPs. Immunostainings on neonatal lamb tracheal rings were used to localize MMP-2 and 9.

RESULTS

Analysis revealed an age-dependent decrease in total MMP-2 quantity and the ratio of active to latent forms. TIMP-2 shows a time-dependent increase throughout airway development. Total MMP-9 and TIMP-1 quantities were unchanged across these ages, although MMP-9 protein was found predominantly in its latent form during development and predominantly in its active form during adulthood. Respiratory epithelial cells reacted positive for both MMP-2 and 9 and trachealis muscle fibers were positive for MMP-2. No MMP-7 expression was identified in the rabbit airway.

CONCLUSIONS

The opposing developmental patterns in MMP-2 expression between the airway and lung lead to speculation regarding the role of MMP-2 activity on changes in organ compliance.

Common cavity pressure during gastroesophageal reflux: reassessment using simultaneous pressure, impedance, and ultrasound imaging

An increase in intraesophageal pressure during transient lower esophageal sphincter (LES) relaxation [referred to as common cavity (CC) pressure] is thought to be a marker of gastroesophageal reflux (GER). Multiluminal impedance (MII) measurement is a sensitive marker of reflux entry into the esophagus during GER. We recorded GER using esophageal pressure, pH, impedance, and intraluminal ultrasound (US) images to understand the genesis of the esophageal CC pressure. Nine normal subjects underwent simultaneous MII/pH/pressure and US image recording of the esophagus for 2 h following a standardized meal. MII and pressure transducers were located at 5 and 15 cm above the LES. The US transducer and pH sensors were also placed at 5 cm above the LES. Refluxate entry into the esophagus by MII criteria was determined relative to the onset of CC pressure wave. Esophageal lumen cross-sectional area (CSA) and muscle CSA during GER were determined from the US images. Eighty liquid GER episodes identified using MII criteria, of which 55 were clearly associated with CC pressure waves, were analyzed. The GER reached 15 cm above LES in 49 of 55 (89%) by MII criteria, but the CC pressure wave was observed at 5 and 15 cm during all episodes. The propagation of the CC pressure wave was simultaneous between 5 and 15 cm during 49 of 55 (89%) of the GER episodes, but reflux entry by MII criteria was retrograde during 53 of 55 (96%) of these episodes. During 5 air-reflux episodes, MII showed a simultaneous reflux entry between the 5- and 15-cm site, however, the CC pressure preceded reflux entry during all of these episodes. There was poor correlation between the luminal CSA and the magnitude of CC pressure (R(2) = 0.144). US images revealed a close temporal correlation between CC pressure and the increase in esophageal muscle thickness and muscle CSA (markers of longitudinal muscle contraction). Disassociation between CC pressure and MII-detected reflux suggests that the onset of CC pressure is not due to GER. We speculate that longitudinal muscle contraction plays an important role in the genesis of CC pressure.

Inhibition of matrix metalloproteinase-9 prevents neutrophilic inflammation in ventilator-induced lung injury

Neutrophils are considered to play a central role in ventilator-induced lung injury (VILI). However, the pulmonary consequences of neutrophil accumulation have not been fully elucidated. Matrix metalloproteinase-9 (MMP-9) had been postulated to participate in neutrophil transmigration. The purpose of this study was to investigate the role of MMP-9 in the neutrophilic inflammation of VILI. Male Sprague-Dawley rats were divided into three groups: 1) low tidal volume (LVT), 7 ml/kg of tidal volume (VT); 2) high tidal volume (HVT), 30 ml/kg of VT; and 3) HVT with MMP inhibitor (HVT+MMPI). As a MMPI, CMT-3 was administered daily from 3 days before mechanical ventilation. Degree of VILI was assessed by wet-to-dry weight ratio and acute lung injury (ALI) scores. Neutrophilic inflammation was determined from the neutrophil count in the lung tissue and myeloperoxidase (MPO) activity in the bronchoalveolar lavage fluid (BALF). MMP-9 expression and activity were examined by immunohistochemical staining and gelatinase zymography, respectively. The wet-to-dry weight ratio, ALI score, neutrophil infiltration, and MPO activity were increased significantly in the HVT group. However, in the HVT+MMPI group, pretreatment with MMPI decreased significantly the degree of VILI, as well as neutrophil infiltration and MPO activity. These changes correlated significantly with MMP-9 immunoreactivity and MMP-9 activity. Most outcomes were significantly worse in the HVT+MMPI group compared with the LVT group. In conclusion, VILI mediated by neutrophilic inflammation is closely related to MMP-9 expression and activity. The inhibition of MMP-9 protects against the development of VILI through the downregulation of neutrophil-mediated inflammation.

EFFECT OF NOS INHIBITION ON RAT GASTRIC MATRIX METALLOPROTEINASE PRODUCTION DURING ENDOTOXEMIA

Matrix metalloproteinases (MMPs) degrade the extracellular matrix and contribute to LPS-induced gastric injury. MMPs are closely modulated by their activators, membrane type-MMP (MT-MMPs) and their endogenous inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). As LPS-induced gastric injury is mediated in part by iNOS, and NO modulates MMP production in vitro, we hypothesized that NOS inhibition would similarly modulate LPS-induced gastric MMP production. Therefore, the purpose of these studies was to compare the effects of selective and nonselective NOS inhibition on LPS-induced gastric MMP production.

METHODS

Sprague-Dawley rats were given either the nonselective NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 5 mg/kg, s.c.), a selective iNOS inhibitor, aminoguanidine (45 mg/kg, i.p.) or L-N-iminoethyl-lysine (L-NIL; 10 mg/kg, i.p.), or vehicle 15 min before saline or LPS (20 mg/kg, i.p.) and killed 24 h after LPS administration. Stomachs were assessed for macroscopic injury (computed planimetry), and gastric mucosal MMP production was assessed by gelatin zymography, in situ zymography, and Western analysis for MMP-2, MT1-MMP, and TIMP-2. (n > or = 4/group; ANOVA).

RESULTS

Aminoguanidine treatment decreased LPS-induced macroscopic gastric injury as well as MMP-2 and MT1-MMP protein production while having no effect on TIMP-2 protein levels. L-NIL similarly attenuated the induction of MMP-2 and MT1-MMP by LPS. L-NAME failed to attenuate LPS induced gastric injury or MT1-MMP protein induction and increased MMP-2 levels. L-NAME similarly had no effect on gastric TIMP-2 production.

CONCLUSIONS

Selective iNOS inhibition decreases gastric MMP-2 activity after LPS administration, whereas nonselective inhibition increases MMP-2 levels. The ability of selective iNOS inhibition to ameliorate LPS-induced gastric injury may be due in part to its inhibition of active MMP-2 production, whereas nonselective NOS inhibitors increase MMP-2 levels and maintain gastric injury after LPS administration.

MMP-9 in serum correlates with the development of pulmonary complications in experimental acute pancreatitis

INTRODUCTION

The prediction of the course of acute pancreatitis and its arising complications is of clinical importance. The aim of this study was to judge the time course and relevance of matrix metalloproteinase-9 (MMP-9), a PMN-derived protease, for the development of pulmonary complications in two models of acute pancreatitis.

METHODS

MMP-9 was evaluated in a standardized experimental model of acute pancreatitis. Mild edematous (n = 12) and severe necrotizing pancreatitis (n = 48) were induced by intravenous cerulein or intravenous cerulein and intraductal application of glycodeoxycholic acid and compared to control animals. 1, 6, 9, 12, 24 and 72 h after induction, rats were sacrificed and damage to the lung and the pancreas was quantified by histology and extravasation of Evans blue. At 1, 6, 9, 12, 24 and 72 h, we determined MMP-9 in serum by ELISA.

RESULTS

In our model, MMP-9 in serum was increased in the group with severe acute pancreatitis in comparison to mild edematous pancreatitis and controls at each evaluated time point (p < 0.05). The maximum release of MMP-9 preceded the development of pulmonary complications, verified by histology and extravasation of Evans blue. MMP-9 showed a negative predictive value of 96.2% and a positive predictive value of 100% for the development of pulmonary complications.

CONCLUSION

MMP-9 in serum allows a valid grouping to severe and mild courses of experimental acute pancreatitis with a good predictive value for the development of pulmonary complications. MMP-9 should be evaluated as a valid single marker for the prediction of progression and the development of pulmonary complications in acute pancreatitis in clinical studies.

Serum matrix metalloproteinase 9 as a marker for the assessment of severe acute pancreatitis

Previous studies have shown that matrix metalloproteinase 9 (MMP-9) degrades basement membrane components in inflammation, but the change of serum MMP-9 level in the progression of acute pancreatitis remains unclear. The aim of our study was to assess the value of MMP-9 as a prognostic marker in acute pancreatitis. The prospective study included 10 patients with severe acute pancreatitis (SAP) and 10 patients with mild acute pancreatitis. The study also enrolled 10 healthy individuals as control. The serum MMP-9 level, serum C-reactive protein (CRP) level, serum tumor necrosis factor alpha (TNF-alpha) level and acute physiology and chronic health evaluation (APACHE) II score were measured at 1 hr and 48 hrs after admission. APACHEII scores and serum MMP-9, TNF-alpha and CRP levels were significantly increased in patients with SAP compared to those with mild acute pancreatitis and control subjects at 1 hr after admission (p < 0.01). When the states of illness were improved, the levels of the above-mentioned markers were decreased in patients with SAP at 48 hrs after admission (1 hr vs 48 hrs, p < 0.01 or p < 0.05). Furthermore, significant positive correlation was found between serum MMP-9 level and serum TNF-alpha level, serum CRP level or APACHEII score in patients at 1 hr after admission (MMP-9/TNF-alpha, r = 0.956; MMP-9/CRP, r = 0.935; MMP-9/APACHE II score, r = 0.957; p < 0.01). These results suggest that MMP-9 is involved in the deterioration of SAP and serum MMP-9 level is a valuable assessment marker for the severity of SAP.

Rat gastric gelatinase induction during endotoxemia

Despite continued investigation, the pathogenesis of tissue injury secondary to sepsis remains elusive. Further evaluation of the mechanisms by which endotoxemia and sepsis induce tissue injury is necessary to formulate rational and effective treatment strategies. The purpose of these studies was to evaluate the role of the matrix metalloproteinases MMP-2 and MMP-9 in gastric injury during lipopolysaccharide induced endotoxemia. Lipopolysaccharide increased gastric gelatinase activity as determined by in situ and gelatin zymography. Specifically, lipopolysaccharide induced MMP-2, MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) transcription, with subsequent increases in MMP-2 and TIMP-1 protein expression. Furthermore, selective metalloproteinase inhibition ameliorated gastric injury in this model. These data suggest that lipopolysaccharide-induced gastric injury is mediated, at least in part, by increased MMP-2 production.

Synchrony between circular and longitudinal muscle contractions during peristalsis in normal subjects

The current understanding is that longitudinal muscle contraction begins before and outlasts circular muscle contraction during esophageal peristalsis in normal subjects. The goal of our study was to reassess the relationship between the contractility of two muscle layers using novel ways to look at the muscle contraction. We studied normal subjects using synchronized high-frequency ultrasound imaging and manometry. Swallow-induced peristalsis was recorded at 5 and 10 cm above the lower esophageal sphincter (LES). Ultrasound (US) images were analyzed for muscle cross-sectional area (CSA) and circularity index of the esophagus during various phases of esophageal contraction. A plot of the M mode US image, muscle CSA, and esophageal circularity index was developed to assess the temporal correlation between various parameters. The muscle CSA wave began before and lasted longer than the contraction pressure wave at both 5 and 10 cm above the LES. M mode US images revealed that the onset of muscle CSA wave was temporally aligned with the onset of lumen collapse. The peak muscle CSA occurred in close proximity with the peak pressure wave. The esophagus started to become more circular (decrease in circularity index) with the onset of the muscle CSA wave. The circularity index and muscle CSA returned to the baseline at approximately the same time. In conclusion, the onset of lumen collapse and return of circularity index of the esophagus are likely to be the true markers of the onset and end of circular muscle contraction. Circular and longitudinal muscle layers of the esophagus contract in a precise synchronous fashion during peristalsis in normal subjects.

Matrix metalloproteinase-9 modulates intestinal injury in rats with transmural colitis

Proteolysis and degradation of extracellular matrix by metalloproteinases (MMPs) may contribute to intestinal injury in inflammatory bowel disease. In the present study, we investigated the pathogenic role of gelatinases (MMP-9 and MMP-2) on transmural colonic injury in a rat model of chronic colitis, which was induced by intracolonic instillation of trinitrobenzene sulfonic acid (TNBS). The activity and expression of MMP-2 and MMP-9 were measured in colonic tissue and peripheral neutrophils by fluorescence, zymography, Western blot, or immunohistochemistry at different time-points. Furthermore, myeloperoxidase content in colonic homogenates was analyzed to evaluate inflammation. Finally, morphological changes were assessed following early or delayed administration of CGS-27023-A, a synthetic inhibitor of MMPs. We found that the induction of colitis led to a significant up-regulation in tissue gelatinase concentration, whereas no changes in collagenase activity were observed. In addition, up-regulation of pro-MMP-9, but not of pro-MMP-2, was found on Days 7 and 10 following the induction of colitis. Furthermore, transmural MMP-9 was detected by immunofluorescent staining in the inflamed tissue. Consistent with tissue samples, neutrophils from colitic rats showed a significantly increased activity of pro-MMP-9. Finally, early but not delayed treatment with CGS-27023-A attenuated colonic mucosal injury in rats with TNBS-induced colitis. In conclusion, up-regulation of MMP-9 in peripheral and colonic neutrophils modulates transmural colonic injury in rats with TNBS-induced colitis.

Recombinant human Clara cell secretory protein in acute lung injury of the rabbit: effect of route of administration

OBJECTIVE

To test the hypothesis that intratracheal instillation of Clara cell secretory protein (CC 10) to the lung may afford greater protection than intravenous administration from ventilator-induced lung inflammation.

DESIGN

Interventional laboratory study.

SETTING

An academic medical research facility in northeastern United States.

SUBJECTS

Sedated, lavage-injured juvenile rabbits.

INTERVENTIONS

A total of 18 juvenile rabbits were anesthetized, ventilated, injured with saline lavage (Pao2 of <100 mm Hg; respiratory compliance of <0.50 mL.cm H2O.kg and <50% baseline), and randomized to receive intratracheally administered surfactant plus no recombinant human CC 10 (rhCC 10, control), intravenous rhCC 10, or intratracheal rhCC 10.

MEASUREMENT AND MAIN RESULTS

Arterial blood chemistry and pulmonary mechanics were monitored; plasma and urine were collected serially. After 4 hrs of ventilation, lungs were lavaged and harvested. Surfactant function was analyzed from bronchoalveolar lavage samples (surfactometry); rhCC 10, interleukin-8, and lung myeloperoxidase concentrations were measured. Pao2, oxygenation index, ventilatory efficiency index, and respiratory compliance were not different across time or group beyond injury. Surfactometry data identified no differences as a function of group or time. Plasma, bronchoalveolar lavage, and lung interleukin-8 concentrations, lung myeloperoxidase concentrations, and inflammatory cell counts in the alveolar and interstitial spaces of intravenous and intratracheal groups were lower than in the control group (p < .05) but not statistically different from each other. Concentrations of rhCC 10 in lung, bronchoalveolar lavage, and plasma were greater in the intratracheal group than in the intravenous group (p<.05). Urine rhCC 10 concentrations were greater for the intravenous group than for the intratracheal group (p<.05) at 1, 3, and 4 hrs after treatment. No group differences in histomorphometry were noted.

CONCLUSIONS

Both intravenous and intratracheal rhCC 10 delivery, after surfactant therapy, effectively decrease lung inflammation vs. surfactant alone. While supporting the physiologic profile, intratracheal instillation results in greater, maintained lung and plasma rhCC 10 pools compared with intravenous administration. As such, intratracheal instillation of rhCC 10 may afford more prolonged protection against lung inflammation than intravenous administration.

N/A

N/A

Effects of an intratracheally delivered anti-inflammatory protein (rhCC10) on physiological and lung structural indices in a juvenile model of acute lung injury

BACKGROUND

Mechanical ventilation results in acute lung trauma that can stimulate processes that alter lung development. Activation of matrix metalloproteinases (MMPs) and their tissue-produced inhibitors (TIMPs) is initiated by the inflammatory response to mechanical ventilation and are involved in breakdown of the basement membrane and parenchymal modeling.

OBJECTIVES

The aim of this study was to test the hypothesis that rhCC10, a lung anti-inflammatory mediator, would foster improved lung function, structural preservation, and a reduction in net MMP activity in a juvenile model of acute lung injury.

METHODS

Twenty-four juvenile rabbits were saline-lavage-injured and treated with 100 or 25 mg/kg surfactant (Survanta, Ross Labs) with or without rhCC10 (Claragen, Inc.; n=6 per group). Animals were ventilated for 4 h, then euthanized for in vitro surfactant function analysis, lung histomorphometry, and analysis of MMP-2, MMP-7, and MMP-9 and TIMPs 1 and 2 in the lung.

RESULTS

Apical lung expansion, reduced with the lower dose of surfactant, was partially restored with the addition of rhCC10. Alveolar septal wall thickness was reduced (p<0.05) with low-dose surfactant plus rhCC10 compared to high-dose surfactant alone. Increased within-group variance in MMP-2 and MMP-9 proteolytic activity was found with the low-dose surfactant and was abolished with rhCC10. MMP-7 was reduced (p<0.05) with rhCC10 administration, independent of surfactant dose.

CONCLUSIONS

Intratracheal administration of the anti-inflammatory rhCC10 resulted in preserved lung structure and MMP/TIMP profile after 4 h of mechanical ventilation, in a surfactant dose-dependent manner.

Extracellular cleavage of E-cadherin by leukocyte elastase during acute experimental pancreatitis in rats

BACKGROUND & AIMS

Cadherins play an important role in cell-cell contact formation at adherens junctions. During the course of acute pancreatitis, adherens junctions are known to dissociate-a requirement for the interstitial accumulation of fluid and inflammatory cells-but the underlying mechanism is unknown.

METHODS

Acute pancreatitis was induced in rats by supramaximal cerulein infusion. The pancreas and lungs were either homogenized for protein analysis or fixed for morphology. Protein sequencing was used to identify proteolytic cleavage sites and freshly prepared acini for ex vivo studies with recombinant proteases. Results were confirmed in vivo by treating experimental pancreatitis animals with specific protease inhibitors.

RESULTS

A 15-kilodalton smaller variant of E-cadherin was detected in the pancreas within 60 minutes of pancreatitis, was found to be the product of E-cadherin cleavage at amino acid 394 in the extracellular domain that controls cell-contact formation, and was consistent with E-cadherin cleavage by leukocyte elastase. Employing cell culture and ex vivo acini leukocyte elastase was confirmed to cleave E-cadherin at the identified position, followed by dissociation of cell contacts and the internalization of cleaved E-cadherin to the cytosol. Inhibition of leukocyte elastase in vivo prevented E-cadherin cleavage during pancreatitis and reduced leukocyte transmigration into the pancreas.

CONCLUSIONS

These data provide evidence that polymorphonuclear leukocyte elastase is involved in, and required for, the dissociation of cell-cell contacts at adherens junctions, the extracellular cleavage of E-cadherin, and, ultimately, the transmigration of leukocytes into the epithelial tissue during the initial phase of experimental pancreatitis.

Matrix metalloproteinase-2 (MMP-2) and MMP-9 in pulmonary pathology

The lung is affected by a variety of disease processes that can lead to considerable morbidity and mortality. As the lung is the only organ for respiration and gas exchange, the structural and functional integrity of the lung is of primary importance. Various pathological processes affect the extracellular matrix (ECM) of the lung in an adverse manner, causing destruction of tissue integrity followed by tissue remodeling, which together impair normal pulmonary function. Matrix metalloproteinases (MMPs) are neutral proteinases that are involved in the breakdown and remodeling of the ECM under a variety of physiological and pathological conditions. MMP-2 and MMP-9, collectively known as the gelatinases, are particularly important in the pathogenesis of inflammatory, infectious, and neoplastic diseases in many organs including the lung. This review examines the expression of MMP-2 and MMP-9 in disease of the lung and discusses the role these gelatinases may play in disease progression.

Leukocyte-derived matrix metalloproteinase-9 mediates blood-brain barrier breakdown and is proinflammatory after transient focal cerebral ischemia

Results of recent studies reveal vascular and neuroprotective effects of matrix metalloproteinase-9 (MMP-9) inhibition and MMP-9 gene deletion in experimental stroke. However, the cellular source of MMP-9 produced in the ischemic brain and the mechanistic basis of MMP-9-mediated brain injury require elucidation. In the present study, we used MMP-9−/−mice and chimeric knockouts lacking either MMP-9 in leukocytes or in resident brain cells to test the hypothesis that MMP-9 released from leukocytes recruited to the brain during postischemic reperfusion contributes to this injury phenotype. We also tested the hypothesis that MMP-9 promotes leukocyte recruitment to the ischemic brain and thus is proinflammatory. The extent of blood-brain barrier (BBB) breakdown, the neurological deficit, and the volume of infarction resulting from transient focal stroke were abrogated to a similar extent in MMP-9−/−mice and in chimeras lacking leukocytic MMP-9 but not in chimeras with MMP-9-containing leukocytes. Zymography and Western blot analysis from these chimeras confirmed that the elevated MMP-9 expression in the brain at 24 h of reperfusion is derived largely from leukocytes. MMP-9−/−mice exhibited a reduction in leukocyte-endothelial adherence and a reduction in the number of neutrophils plugging capillaries and infiltrating the ischemic brain during reperfusion; microvessel immunopositivity for collagen IV was also preserved in these animals. These latter results document proinflammatory actions of MMP-9 in the ischemic brain. Overall, our findings implicate leukocytes, most likely neutrophils, as a key cellular source of MMP-9, which, in turn, promotes leukocyte recruitment, causes BBB breakdown secondary to microvascular basal lamina proteolysis, and ultimately contributes to neuronal injury after transient focal stroke.

N/A

N/A

Neutrophil-mediated secretion and activation of matrix metalloproteinase-9 during cardiac surgery with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) induces neutrophil activation, degranulation, and a systemic inflammatory response. Matrix metalloproteinase (MMP)-9 exists in neutrophils and is released on neutrophil activation. Increased levels of MMP-9 have been observed in patients undergoing CPB. We designed the present study to determine whether MMP-9 is derived from neutrophils during CPB. Twenty-one patients undergoing elective coronary artery bypass grafting with or without CPB were included in this study. Blood was collected and analyzed for MMP-9 and tissue inhibitor of metalloproteinase (TIMP)-1. Neutrophils were also isolated and examined for MMP-9 production and mRNA expression. Plasma levels and activity of MMP-9 increased significantly 2-6 h after beginning CPB, whereas the MMP-9 levels in patients with off-pump cardiac surgery did not increase. The neutrophil content of MMP-9 and mRNA increased significantly 2 h after beginning CPB. The plasma levels of TIMP-1 increased gradually for 6 h, whereas the MMP-9/TIMP-1 ratios were increased 2-4 h after beginning CPB. The present study demonstrated that CPB causes an increase in the concentration and activity of plasma MMP-9. The corresponding increase in neutrophil MMP-9 expression and production suggests that MMP-9 is derived primarily from neutrophils and may contribute to the inflammatory response associated with CPB.

Transient lower esophageal sphincter relaxations (TLESRs) are the major mechanism of gastroesophageal reflux but are not the cause of reflux disease

In healthy subjects, the rate of acid reflux during transient lower esophageal sphincter relaxations (TLESRs) is more frequent at the proximal margin of the LES. In this study, we investigated the hypothesis that the rate of acid reflux at the proximal margin of LES during TLESRs is similar in reflux disease to that in healthy subjects. Concurrent esophageal manometry and pH monitoring were performed in the sitting position for 3 hr after a standard meal in 10 patients with reflux disease and 10 age-matched healthy controls. The rate of TLESRs in patients with reflux disease (5.0/hr [3.3-6.7]; median [interquartile range]) was similar to that of controls (4.5/hr [3.7-5.7]). The incidence of acid reflux 7 cm above the LES during TLESRs in patients (48.1% [27.2-71.4%]) was significantly higher than that in controls (10.9% [0.0-18.8%]) but there was no difference 2 cm above the LES (75.0 [69.2-87.5] vs. 74.3 [55.5-90.0%]). The rate of TLESRs and the incidence of acid reflux during TLESRs are not increased in reflux disease. These findings, therefore, indicate that reflux disease is not a disorder of TLESRs and relates more to the proximal extent of the refluxate.

Crural diaphragm inhibition during esophageal distension correlates with contraction of the esophageal longitudinal muscle in cats

Esophageal distension causes simultaneous relaxation of the lower esophageal sphincter (LES) and crural diaphragm. The mechanism of crural diaphragm relaxation during esophageal distension is not well understood. We studied the motion of crural and costal diaphragm along with the motion of the distal esophagus during esophageal distension-induced relaxation of the LES and crural diaphragm. Wire electrodes were surgically implanted into the crural and costal diaphragm in five cats. In two additional cats, radiopaque markers were also sutured into the outer wall of the distal esophagus to monitor esophageal shortening. Under light anesthesia, animals were placed on an X-ray fluoroscope to monitor the motion of the diaphragm and the distal esophagus by tracking the radiopaque markers. Crural and costal diaphragm electromyograms (EMGs) were recorded along with the esophageal, LES, and gastric pressures. A 2-cm balloon placed 5 cm above the LES was used for esophageal distension. Effects of baclofen, a GABA(B) agonist, were also studied. Esophageal distension induced LES relaxation and selective inhibition of the crural diaphragm EMG. The crural diaphragm moved in a craniocaudal direction with expiration and inspiration, respectively. Esophageal distension-induced inhibition of the crural EMG was associated with sustained cranial motion of the crural diaphragm and esophagus. Baclofen blocked distension-induced LES relaxation and crural diaphragm EMG inhibition along with the cranial motion of the crural diaphragm and the distal esophagus. There is a close temporal correlation between esophageal distension-mediated LES relaxation and crural diaphragm inhibition with the sustained cranial motion of the crural diaphragm. Stretch caused by the longitudinal muscle contraction of the esophagus during distension of the esophagus may be important in causing LES relaxation and crural diaphragm inhibition.

Pancreatic proteases in serum induce leukocyte-endothelial adhesion and pancreatic microcirculatory failure

BACKGROUND

Neutrophil-mediated tissue injury in acute pancreatitis includes a severe reduction of the functional microcirculation via interaction of adhesion molecules on leukocytes (MAC-1) and endothelium (ICAM-1). The hypothesis of the study was that trypsin and elastase in serum alone lead to the expression of these complementary adhesion molecules and result in increased leukocyte-endothelial interaction (LEI). In addition we evaluated the preventative benefit of protease inhibition on these mechanisms.

MATERIALS AND METHODS

In vitro: Cultured endothelial cells (HUVEC) and human leukocytes (PMN) were stimulated with increasing doses of trypsin and elastase. In addition, pre-treatment of PMN or HUVEC was performed with protease inhibitors (Nafamostat mesilate, FUT and gabexate mesilate, FOY). The expression of ICAM-1 or MAC-1 was evaluated by flow cytometry. In vivo: Severe pancreatitis was induced in rats. Microcirculatory disturbances were evaluated by real-time confocal microscopy at 9 h in controls and acute pancreatitis with or without anti-protease treatment. Additionally, the effect of continuous trypsin and elastase infusion on pancreatic microcirculation and LEI were evaluated by intravital fluorescence videomicroscopy.

RESULTS

Up-regulation of MAC-1 and ICAM-1 expression requires the presence of serum. The maximal increase of MAC-1 and ICAM-1 expression was found at concentrations of trypsin or elastase characteristic for acute pancreatitis. FUT or FOY significantly reduced protease-induced expression of MAC-1 and ICAM-1. Real-time in-vivo microscopy revealed that functional capillary density in acute pancreatitis was significantly reduced (267.1 +/- 2.95/mm2 vs. 91.29 +/- 12.81/mm2) and treatment with FUT significantly reduced this effect (134.6 +/- 4.6/mm2; p < 0.05 vs. untreated pancreatitis). Infusion of trypsin or elastase alone increased LEI in vivo and reduced pancreatic perfusion.

CONCLUSION

Both trypsin and elastase up-regulate the expression of adhesion molecules on leukocytes and endothelial cells in the presence of serum. Increased LEI and reduced perfusion of the pancreas, characteristic of acute pancreatitis, is induced in vivo by infusion of pancreatic proteases and this effect is partially abrogated by their inhibitors. These results support the role of circulating trypsin and elastase in promoting pancreatic microcirculatory failure in experimental acute pancreatitis.

Neuroprotection by inhibition of matrix metalloproteinases in a mouse model of intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is an acute neurological disorder without effective treatment. Mechanisms of acute brain injury after ICH remain to be clarified. Although a few studies suggested a detrimental role for the gelatinase matrix metalloproteinase (MMP)-9 in ICH, the relationship between MMP-9 activity and acute brain injury after ICH is not determined. In this study, we first examined the expression of gelatinases in vivo using a collagenase-induced mouse model of ICH. Gel zymography revealed that MMP-9 was activated and upregulated after ICH. In situ zymography showed that gelatinase activity was mostly co-localized with neurons and endothelial cells of the blood vessel matrix. Inhibition with a broad-spectrum metalloproteinase inhibitor GM6001 (100 mg/kg) ameliorated dysregulated gelatinase activity, neutrophil infiltration, production of oxidative stress, brain oedema and degenerating neurons. Functional improvement and a decrease in injury volume were also observed. We provide evidence that MMP-9 may play a deleterious role in acute brain injury within the first 3 days after ICH. Blockade of MMP activity during this critical period may have efficacy as a therapeutic strategy for the treatment of acute brain injury after ICH.

Borrelia burgdorferi, host-derived proteases, and the blood-brain barrier

Neurological manifestations of Lyme disease in humans are attributed in part to penetration of the blood-brain barrier (BBB) and invasion of the central nervous system (CNS) by Borrelia burgdorferi. However, how the spirochetes cross the BBB remains an unresolved issue. We examined the traversal of B. burgdorferi across the human BBB and systemic endothelial cell barriers using in vitro model systems constructed of human brain microvascular endothelial cells (BMEC) and EA.hy 926, a human umbilical vein endothelial cell (HUVEC) line grown on Costar Transwell inserts. These studies showed that B. burgdorferi differentially crosses human BMEC and HUVEC and that the human BMEC form a barrier to traversal. During the transmigration by the spirochetes, it was found that the integrity of the endothelial cell monolayers was maintained, as assessed by transendothelial electrical resistance measurements at the end of the experimental period, and that B. burgdorferi appeared to bind human BMEC by their tips near or at cell borders, suggesting a paracellular route of transmigration. Importantly, traversal of B. burgdorferi across human BMEC induces the expression of plasminogen activators, plasminogen activator receptors, and matrix metalloproteinases. Thus, the fibrinolytic system linked by an activation cascade may lead to focal and transient degradation of tight junction proteins that allows B. burgdorferi to invade the CNS.

Upregulation of matrix metalloproteinases following nerve injury is not mediated by mast cell activation

OBJECTIVE

Matrix metalloproteinases (MMPs) contribute to inflammatory and degenerative processes in injured nerves. Since mast cells release mediators which upregulate and activate MMPs, we tested the hypothesis that activation of mast cells is responsible for changes in the expression and activity of MMP-2 and MMP-9 in the injured peripheral nerve.

METHODS

The sciatic nerve was partially ligated in Wistar rats in which mast cells were stabilized with sodium cromoglycate. Expression and activity of MMP-2 and MMP-9 were measured in the injured and contralateral nerve using gelatin zymography, and compared between mast cell-stabilized and control groups.

RESULTS

Expression and activity of MMP-9 were increased in both the injured and contralateral nerve, but activity of MMP2 was slightly reduced by nerve injury. However, stabilization of mast cells did not alter the changes in expression or activity of MMP-2 and MMP-9 following nerve injury.

CONCLUSION

These findings suggest that the contribution of MMP-9 upregulation to the inflammatory and degenerative changes that follow nerve injury is independent of mast cell activation.

Interpreting Gelatinase Activity in Tumor Tissue and Serum as a Prognostic Marker of Naturally Developing Canine Tumors

To evaluate the clinical usefulness of tissue and serum gelatinase activity as a prognostic marker of canine tumors, tissue samples from 60 tumors and corresponding serum samples from the same animals were collected at the time of biopsy and surgery. On the basis of histopathology and clinical aggressiveness of metastasis and recurrence (MR), the cases were divided into 6 categories: non-inflammatory (Inf(-)) and inflammatory (Inf(+)) benign, and the Inf(-) MR(-), Inf(-) MR(+), Inf(+) MR(-), and Inf(+) MR(+) malignant. Gelatinase activity was determined semi-quantitatively using gelatin zymogram with a gelatinase standard from cultured canine peripheral blood mononuclear cells stimulated with lipopolysaccharide. No significant difference in gelatinase activities in tissue extracts was evident between the benign and malignant tumors. Inf(+) benign tumors, as well as Inf(-) MR(+), Inf(+) MR(-) and Inf(+) MR(+) malignant tumors, showed significantly higher tissue gelatinase activity than Inf(-) benign. The tissue activity in Inf(-) MR(-) malignant was significantly lower than in Inf(+) MR(-) and Inf(+) MR(+) malignant. The serum activity was significantly higher in the malignant cases than in the control and the benign. Inf(-) MR(+), Inf(+) MR(-) and Inf(+) MR(+) malignant tumors induced significantly higher gelatinase activity in serum than Inf(-) benign tumors. Gelatinase activity in serum was positively correlated with that in tumor extracts. Increased gelatinase in tumor tissue and serum may be correlated with inflammation as well as tumor aggressiveness, and thus should be used in combination with histopathology for predicting tumor metastasis or recurrence.

Control of inflammatory pain by chemokine-mediated recruitment of opioid-containing polymorphonuclear cells

Opioid-containing leukocytes can counteract inflammatory hyperalgesia. Under stress or after local injection of corticotropin releasing factor (CRF), opioid peptides are released from leukocytes, bind to opioid receptors on peripheral sensory neurons and mediate antinociception. Since polymorphonuclear cells (PMN) are the predominant opioid-containing leukocyte subpopulation in early inflammation, we hypothesized that PMN and their recruitment by chemokines are important for peripheral opioid-mediated antinociception at this stage. Rats were intraplantarly injected with complete Freund's adjuvant (CFA). Using flow cytometry, immunohistochemistry, and ELISA, leukocyte subpopulations, chemokine receptor (CXCR2) expression on opioid-containing leukocytes and the CXCR2 ligands keratinocyte-derived chemokine (KC), macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant-2 (CINC-2) were quantified. Paw pressure threshold (PPT) was determined before and after intraplantar and subcutaneous injection of CRF with or without naloxone. PMN depletion was achieved by intravenous injection of an antiserum. Chemokines were blocked by intraplantar injection of anti-MIP-2 and/or anti-KC antiserum. We found that at 2 h post CFA (i) intraplantar but not subcutaneous injection of CRF produced dose-dependent and naloxone-reversible antinociception (P<0.05, ANOVA). (ii) Opioid-containing leukocytes in the paw and CRF-induced antinociception were reduced after PMN depletion (P<0.05, t-test). (iii) Opioid-containing leukocytes mostly expressed CXCR2. MIP-2 and KC, but not CINC-2 were detectable in inflamed but not in noninflamed tissue (P<0.05, ANOVA). (iv) Combined but not single blockade of MIP-2 and KC reduced the number of opioid-containing leukocytes and peripheral opioid-mediated antinociception (P<0.05, t-test; P>0.05, ANOVA). In summary, in early inflammation peripheral opioid-mediated antinociception is critically dependent on PMN and their recruitment by CXCR2 chemokines.

Effects of matrix metalloproteinase inhibitor on LPS-induced goblet cell metaplasia

Bacterial infections of the lung are known to induce inflammatory responses, which lead to mucus hypersecretion. Moreover, mucin synthesis in the airways has been reported to be regulated by neutrophilic inflammation-induced epidermal growth factor receptor (EGFR) expression and its activation. Furthermore, matrix metalloproteinases (MMPs), especially MMP-9, have been reported to promote the transmigration of activated neutrophils. In this study, we investigated the associations between lipopolysaccharide (LPS)-induced goblet cell (GC) metaplasia and EGFR expression and the effects of MMP inhibitor (MMPI). Various concentrations of LPS were instilled into the tracheas of pathogen-free Sprague-Dawley rats, and airways were examined at different times after LPS instillation. To examine the role of MMP-9, we treated rats 3 days before LPS instillation and daily thereafter with MMPI. Neutrophilic infiltration, Alcian blue/periodic acid-Schiff (AB/PAS) staining, and immunohistochemical staining for MUC5AC, EGFR, and MMP-9 were performed. The instillation of LPS increased AB/PAS and MUC5AC staining in time- and dose-dependent manners, and treatment with MMPI significantly prevented GC metaplasia. The instillation of LPS into the trachea also induced neutrophilic infiltration and EGFR and MMP-9 expression in the airway epithelium, and MMPI was found to significantly prevent neutrophil recruitment, GC metaplasia, and EGFR and MMP-9 expression. This study demonstrates that the MMP-9 and EGFR cascades are associated with LPS-induced mucus hypersecretion.

Intracellular and Cell Surface Localization of a Complex between αMβ2 Integrin and Promatrix Metalloproteinase-9 Progelatinase in Neutrophils

We have recently demonstrated that promatrix metalloproteinases (proMMPs), particularly proMMP-9, are potent ligands of the leukocyte beta(2) integrins. We studied here the complex formation between proMMP-9 and alpha(M)beta(2), the major MMP and integrin of neutrophils. On resting neutrophils, the proMMP-9/alpha(M)beta(2) complex was primarily detected in intracellular granules, but after cellular activation it became localized to the cell surface, as demonstrated by immunoprecipitation and double immunofluorescence. Further indication of the complex formation was that neutrophils and alpha(M)beta(2)-transfected L cells, but not the wild-type L cells or leukocyte adhesion deficiency cells, bound to immobilized proMMP-9 or its recombinant catalytic domain in a beta(2) integrin-dependent manner. Peptides that bound to the alpha(M) integrin-I domain and inhibited its complex formation with proMMP-9 prevented neutrophil migration in a transendothelial assay in vitro and in a thioglycolate-elicited peritonitis in vivo. These results suggest that the translocating proMMP-9/alpha(M)beta(2) complex may be part of the cell surface machinery guiding neutrophil migration.

Pancreatic trypsin increases matrix metalloproteinase-9 accumulation and activation during acute intestinal ischemia-reperfusion in the rat

Ischemia-reperfusion of the intestine produces a set of inflammatory mediators, the origin of which has recently been shown to involve pancreatic digestive enzymes. Matrix metalloproteinase-9 (MMP-9) participates in a variety of inflammatory processes including myocardial, hepatic, and pancreatic ischemia-reperfusion. In the present study, we explore the role of neutrophil-derived MMP-9 in acute intestinal ischemia-reperfusion and its interaction with pancreatic trypsin. Male Sprague-Dawley rats were subjected to 45 minutes of superior mesenteric arterial occlusion followed by 90 minutes of reperfusion. In situ zymography of the proximal jejunum reveals increased gelatinase activity in the intestinal wall after ischemia-reperfusion. Gel electrophoresis zymography and immunofluorescence co-localization suggests that this gelatinase activity is derived from MMP-9 released from infiltrating neutrophils. The role of intraluminal trypsin in this process was investigated using an in vivo isolated jejunal loop model of intestinal ischemia-reperfusion. Trypsin increased the inflammatory response after reperfusion, with an augmented neutrophil infiltration of the intestinal wall. Furthermore, trypsin stimulated a rapid conversion of neutrophil-released proMMP-9 into the lower molecular weight enzymatically active MMP-9. This process represents a powerful in vivo pathophysiological mechanism for trypsin-induced MMP-9 activation and is likely to play a central role in the development of acute intestinal inflammation and shock.

Increased circulating 92 kDa matrix metalloproteinase (MMP-9) activity in exacerbations of asthma

BACKGROUND

The 72 kDa matrix metalloproteinase 2 (MMP-2) and the 92 kDa matrix metalloproteinase 9 (MMP-9) are type IV collagenases implicated in various aspects of inflammation including accumulation of inflammatory cells, tissue injury, and development of remodelling. The role of these enzymes in the pathogenesis of asthma exacerbations is unknown.

METHODS

Circulating levels of MMP-2 and MMP-9 proteins and the expression of their inhibitor, tissue inhibitor of metalloproteinase 1 (TIMP-1), were measured in 21 patients experiencing an asthma exacerbation and 21 age matched patients with stable asthma. Circulating gelatinolytic activity was compared during the asthma exacerbation and during subsequent convalescence by gelatin zymography in the same individuals. In addition, MMP-9 specific activity was quantified with a colorimetric assay which uses an artificial proenzyme containing a specific domain recognised by MMP-9 in the same paired samples.

RESULTS

A significant increase in the circulating level of MMP-9 was seen in patients with an asthma exacerbation compared with patients with stable asthma (202.9 (22.0) v 107.7 (9.9) ng/ml, p=0.0003). There were no significant differences in the circulating levels of MMP-2 or TIMP-1. Gelatin zymography identified two major circulating gelatinolytic activities corresponding to MMP-2 and MMP-9, and showed that asthma exacerbations are characterised by markedly increased MMP-9 activity with no significant change in MMP-2 activity compared with the activities during convalescence in the same individuals. Direct measurement showed that MMP-9 specific activity is significantly increased during asthma exacerbations compared with subsequent convalescence (269.6 (31.7) v 170.4 (12.6) ng/ml, p=0.0099).

CONCLUSIONS

Asthma exacerbations are characterised by increased circulating MMP-9 activity. This increased activity may be related to exaggerated airway inflammation and airway remodelling.

Late ischemic preconditioning of the myocardium alters the expression of genes involved in inflammatory response

Myocardial ischemic preconditioning (IPC) is a potent endogenous mechanism of cardioprotection against ischemia-reperfusion injury. In this study we focused on the second phase of IPC as the most interesting in terms of therapeutic implementations. We aimed at the detection of genes, which are differentially expressed at 16 h after reperfusion. Preconditioning of canine myocardium was initiated by 5 min occlusion of the left anterior descending coronary artery with subsequent reperfusion. cDNA representational difference analysis in combination with microarray hybridization and reverse transcription polymerase chain reaction were used to reveal the changes in gene expression in canine hearts. We found that functionally related genes for tristetraproline (TTP), selectin E, matrix metalloproteinase 9, and tumor necrosis factor-alpha were highly upregulated at the late phase of IPC. The upregulation of TTP gene at the late phase of IPC, reported here for the first time, may represent a cardioprotective mechanism, which could be a promising perspective in clinical interventions against ischemia-reperfusion injuries of the heart.

Expression of IL-6 and integrin family cell adhesion molecules in acute necrotizing pancreatitis complicated with multiple organ injury in rats

AIM

To detect the expression of integrin family cellular adhesion molecules LFA-1, Mac-1 and IL-6 in acute necrotizing pancreatitis complicated with multiple organ injury.

METHODS

The flow cytometer was used to detect the expression of LFA-1 and Mac-1 on leukocyte and the radio-immunity to detect the IL-6 in acute necrotizing pancreatitis of rats at different time points.

RESULTS

The expression of LFA-1 and Mac-1 increased significantly in acute pancreatitis group compared with that in control group at all time points (P<0.01), i.e.: LFA-1: 1 h, 7.6±0.4 vs 22.7±1.6; 3 h, 7.9±0.5 vs 26.7±5.5; 6 h, 13.5±1.8 vs 30.3±1.6; 12 h, 9.7±0.7 vs 20.3±4.2; 24 h, 10.1±1.1 vs 15.9±0.7. Mac-1: 1 h, 6.2±1.1 vs 7.0±2.5; 3 h, 6.3±0.8 vs 36.0±1.5; 6 h, 7.9±1.2 vs 27.1±1.4; 12 h, 6.4±0.4 vs 22.5±2.1; 24 h, 7.1±0.4 vs 20.6±1.6. Expression of IL-6 increased significantly in acute pancreatitis group compared with that in control group, i.e.: 1 h, 65.6±3.2 vs 72.4±4.0 (P<0.05); 3 h, 68.2±5.5 vs 155.3±16.3 (P<0.01); 6 h, 69.3±2.6 vs 229.2±16.4 (P<0.01); 12 h, 73.4±2.6 vs 287.7±13.9 (P<0.01); 24 h, 76.9±3.3 vs 289.5±16.1 (P<0.01). Morphological examination demonstrated that inflammatory cells, insterstitial edema, interstitial hemorrhage, desquamation and disintegration occurred in the lungs and kidneys.

CONCLUSION

IL-6, LFA-1 and Mac-1 may play the very active role in acute pancreatitis.

Serine proteases of the fibrinolysis pathway are not involved in lethal hepatitis and fibrinogen breakdown induced by tumor necrosis factor

Tumor necrosis factor (TNF) plays a key role in several types of fulminant and acute hepatitis, and induces massive apoptosis and necrosis of hepatocytes. Our previous studies described the central role played by several matrix metalloproteinases (MMPs) and one or more unknown serine proteases. The aim of this study was to investigate the involvement of serine proteases of the fibrinolytic pathway, known to be activators of several MMPs, in TNF-induced hepatitis and fibrinogen (FG) breakdown. Experiments were performed in a model of TNF-induced hepatitis, consisting of administration of TNF in combination with D-(+)-galactosamine (GalN) to mice deficient in urokinase-type plasminogen (PG) activator (u-PA), tissue-type PG activator (t-PA) or PG. Lethality, transaminase release, increased plasma clotting time and FG levels were measured. In PA- and PG-deficient mice, TNF/GalN still induced hepatitis, as well as increased clotting time and FG breakdown. MMP-9 activation still occurred in the liver despite the lack of plasmin. The data suggest that the serine proteases involved in TNF-induced lethal hepatitis are no constituents of the fibrinolytic cascade.

Pulmonary matrix metalloproteinase excess in hospital-acquired pneumonia

In hospital-acquired pneumonia, extracellular matrix destruction is common and may be caused by excessive activity of matrix metalloproteinases (MMPs). Thirty patients with hospital-acquired pneumonia and 16 control subjects were studied. We evaluated the concentrations of MMP-8, MMP-9, and tissue inhibitor of metalloproteinase-1 in mini-bronchoalveolar lavage fluid (mini-BALF) and blood using zymography and specific immunoassays. In patients with hospital-acquired pneumonia concentrations of MMP-8 and MMP-9 in mini-BALF were increased 10-fold, whereas their specific inhibitor tissue inhibitor of metalloproteinase-1 was not concomitantly increased. In 80% of patients with pneumonia, but in none of the control subjects, the active form of MMP-9 was detected by zymography. Zymography furthermore showed the banding pattern of neutrophil-derived MMP-9, indicating that neutrophils were the main source of MMP-9. Comparison of neutrophils from blood and mini-BALF showed higher basal release of MMPs by pulmonary neutrophils. Stimulation analysis indicated that pulmonary neutrophils were already maximally activated. In patients with detection of potentially pathogenic microorganisms, concentrations of MMPs were fivefold increased compared with patients with negative cultures. Furthermore, MMP-levels were related to clinical severity. These are the first data suggesting that neutrophil-derived MMPs are increased in hospital-acquired pneumonia in association to the detection of causative microorganisms and clinical severity.