Matrix metalloproteinase-9 derived from polymorphonuclear neutrophils increases gut barrier dysfunction and bacterial translocation in rat severe acute pancreatitis. Surgery. 2009;145:147-156. [PMID: 19167969 DOI: 10.1016/j.surg.2008.08.036]

miRNA transcriptomics analysis shows miR-483-5p and miR-503-5p targeted miRNA in extracellular vesicles from severe acute pancreatitis-associated lung injury patients

AIM

This study sought to identify potential biomarkers and miRNA-mRNA networks within extracellular vesicles (EVs) for detecting severe acute pancreatitis-associated lung injury (SAPALI).

METHODS

Blood-derived EVs were isolated, and their miRNA transcriptomic profiles were comprehensively analyzed using miRBase v.21 database along with miRDeep2 tool to predict novel miRNAs. DEGseq R package was deployed for the identification of differentially expressed miRNAs (DEMs). Protein-protein interaction (PPI) networks were assembled using STRING and Cytoscape. A lung injury model was established using Lipopolysaccharide (LPS)-induced BEAS-2B cells, chosen for their respiratory epithelial origin and pertinent association with lung injury. The expression levels of targeted miRNA and associated proteins, TLR4, NF-κB mRNA were quantified via RT-PCR and Western Blot. Levels of IL-6, IL-1β, TNF-α, and ROS were measured using designated kits. Dual-luciferase reporter assay was conducted to examine the interaction between miRNA and proteins.

RESULTS

The comparisons between the SAPALI and the control group revealed 10 DEM, including miR-503-5p and miR-483-5p. The cytoHubba plugin in Cytoscape identified three principal miRNA-mRNA interactions: miR-483-5p with PTK2 and HDAC2; miR-28-5p with MAPK1, TP53BP1, SEMA3A; and miR-503-5p with PPP1CB, SEMA6D, EPHB2, UNC5B. The SAPALI model exhibited elevated miR-503-5p, HDAC2 and inflammatory markers, with a decline UNC5B, miR-483-5p and miR-28-5p. Transfection with miR-503-5p and miR-483-5p inhibitors increased the levels of their supposed binding proteins but not miR-28-5p inhibitor. The Dual-luciferase reporter gene assay identified the interaction of miR-503-5p with UNC5B, and miR-483-5p with HDAC2, but not miR-28-5p with TP53BP1.

CONCLUSIONS

Our study maps miRNA-mRNA interactions in SAPALI, identifying miR-503-5p and miR-483-5p as critical regulatory miRNAs.

Fentanyl alleviates intestinal mucosal barrier damage in rats with severe acute pancreatitis by inhibiting the MMP-9/FasL/Fas pathway

BACKGROUND

Fentanyl is an analgesic used against pancreatitis-related pain, while whether it ameliorates severe acute pancreatitis (SAP) has yet to be checked. The present study aims to determine fentanyl-delivered effect on SAP and the mechanism underlying this effect.

METHODS

Rat SAP models were established, following fentanyl treatment. The serum activity of amylase (AMY), lipase (LIP) and diamine oxidase (DAO) was detected by enzyme-linked immunosorbent assay. Histological examination was performed in the pancreatic and intestinal tissues with hematoxylin-eosin staining. After transfection with matrix metalloproteinase (MMP)9 overexpression plasmids, Caco-2 monolayers were treated with fentanyl and subsequently exposed to lipopolysaccharide (LPS). The transepithelial electrical resistance (TEER) value was determined in rat intestinal mucosa through an Ussing chamber assisted by Analyze & Acquire, and in Caco-2 cell monolayers through a voltohmmeter. Intestinal mucosa and paracellular permeabilities were determined by fluorescein isothiocyanate (FITC)-labeled dextran assay. The expressions of ZO-1, Occludin, MMP9, Fas and Fas ligand (FasL) in rat intestinal mucosa and/or Caco-2 monolayers were analyzed by qRT-PCR or/and western blot.

RESULTS

Fentanyl alleviated SAP-related histological alterations in the pancreas and intestines, reduced the elevated levels of SAP-related AMY, LIP and DAO, but promoted the levels of ZO-1 and Occludin. In SAP rats and Caco-2 monolayers, SAP-related or LPS-induced TEER value decreases, permeability increases, and increases in the expressions of MMP9, Fas and FasL were reversed partly by fentanyl. Notably, MMP9 overexpression could reverse the above fentanyl-delivered in vitro effects.

CONCLUSION

Fentanyl alleviates intestinal mucosal barrier damage in rats with SAP by inhibiting the MMP9/FasL/Fas pathway.

Matrix metalloproteinases and their inhibitors in pediatric severe acute pancreatitis

BACKGROUND

Acute pancreatitis (AP) is increasing in incidence in adult and pediatric patients. Identification of patients at high risk for progression to severe acute pancreatitis (SAP) is crucial, as it can lead to increased mortality and health system cost. Matrix metalloproteinases (MMPs) are endopeptidases which degrade extracellular matrix proteins and increase activity of pro-inflammatory cytokines. Tissue inhibitors of metalloproteinases (TIMPs) regulate MMP activity. Prior limited studies of MMPs and TIMPs have found some to be associated with development of SAP. The aim of this study was to further investigate the role of MMPs and TIMPs in detecting pediatric patients at risk for developing moderately severe AP or SAP.

METHODS

Plasma samples were prospectively collected for patients <21 years of age presenting with AP between November 2015 and October 2019, along with healthy controls. Bead-based multiplex assays were utilized to test levels of 12 MMPs and TIMPs.

RESULTS

Samples were collected from 7 subjects who developed SAP, 7 with moderately severe AP, 45 with mild AP and 44 healthy controls. MMP-9 (p = 0.04) and TIMP-1 (p = 0.01) levels were significantly higher in SAP patients. A multivariable logistic regression model using MMP-9 and TIMP-1 predicted SAP (AUROC 0.87, 95% CI 0.76-0.98).

CONCLUSION

We have demonstrated that MMP9 and TIMP1 levels are increased at AP presentation in pediatric patients who developed SAP during the course of illness. Further studies are needed to validate the use of MMPs and TIMPs as predictive tools for development of SAP in pediatric pancreatitis.

Inhibition of Matrix Metalloproteinase with BB-94 Protects against Caerulein-Induced Pancreatitis via Modulating Neutrophil and Macrophage Activation

Methods

AP was induced in Balb/C mice by ten hourly intraperitoneal injections of caerulein (100 μg/kg) and LPS (5 mg/kg). The MMP inhibitor, BB-94 (20 mg/kg) was intraperitoneally administered 30 min before AP induction. Pancreatitis was confirmed by histology and serum amylase and lipase. Expression of pancreatic proinflammatory mediators and NF-κB activation were assessed. Bone marrow-derived neutrophils (BMDNs) and macrophages (BMDMs) were isolated. BMDNs were activated by phorbol 12-myristate 13-acetate (PMA, 50 ng/ml) and neutrophil reactive oxygen species (ROS) production was recorded. BMDMs were stimulated with 10 ng/ml IFN-γ and 100 ng/ml LPS to induce M1 macrophage polarization.

Results

Pancreatic MMP-9 was markedly upregulated and serum MMP-9 was increased in caerulein-induced pancreatitis. Inhibition of MMP with BB-94 ameliorated pancreatic tissue damage and decreased the expression of proinflammatory cytokines (TNFα and IL-6) or chemokines (CCL2 and CXCL2) and NF-κB activation. Furthermore, using isolated BMDNs and BMDMs, we found that inhibition of MMP with BB-94 markedly decreased neutrophil ROS production, inhibited inflammatory macrophage polarization and NF-κB activation.

Conclusions

Our results showed that inhibition of MMP with BB-94 protected against pancreatic inflammatory responses in caerulein-induced pancreatitis via modulating neutrophil and macrophage activation.

NOX1/NADPH oxidase in bone marrow-derived cells modulates intestinal barrier function

The involvement of reactive oxygen species (ROS) has been suggested in the development of inflammatory bowel disease (IBD). An impaired intestinal barrier function is common in IBD patients. Here, we report the central role of NOX1/NADPH oxidase, a major source of ROS in nonphagocytic cells, in intestinal barrier dysfunction. By in vivo imaging using L-012 as a probe, a time-dependent increase in ROS was demonstrated in the abdomen of wild-type mice (WT) administered lipopolysaccharide (LPS: 6 mg/kg i.p.), but it was almost completely abolished in mice deficient in Nox1 (Nox1-KO) or the inducible nitric oxide synthase gene (iNOS-KO). By ex vivo imaging, increased ROS production was mainly shown in the ileum, where enhanced immunostaining of NOX1 was observed on the apical side of the epithelium. On the other hand, a punctate staining pattern of 3-nitrotyrosine, a marker of peroxynitrite production, was demonstrated in the lamina propria. When LPS-induced intestinal hyperpermeability was assessed by the oral administration of fluorescein isothiocyanate-conjugated dextran (FD-4), it was significantly suppressed in Nox1-KO as well as iNOS-KO. When Nox1-KO adoptively transferred with WT bone marrow were treated with LPS, the serum level of FD-4 was significantly elevated, whereas it remained unchanged in WT receiving bone marrow derived from Nox1-KO. Concomitantly, the activation of matrix metalloproteinase-9 induced by LPS was alleviated not only in intestinal tissue but also in peritoneal macrophages of Nox1-KO. Up-regulation of iNOS by LPS was significantly inhibited in macrophages deficient in Nox1, illustrating a functional hierarchy in NOX1/iNOS signaling. Together, these findings suggest that NOX1 in bone marrow-derived cells, but not epithelial cells, perturbs intestinal barrier integrity during endotoxemia.

Bacterial translocation in acute pancreatitis

Bacterial translocation is a phenomenon in which live bacteria or their products cross the intestinal barrier to other organs or the circulatory system. Gut translocation of bacteria has been reported in both animal models, and clinical trials often accompany acute pancreatitis and are believed to be linked to patient outcome, especially in severe acute pancreatitis. Therefore, the mechanisms of intestinal bacterial translocation in acute pancreatitis have become a topic of interest in recent years. This review discusses Bacterial translocation in acute pancreatitis, identifies possible mechanisms of action, and provides an overview of the methods used to detect Bacterial translocation in acute pancreatitis. This review also highlights areas that require further research.

Potential Prognostic Markers of Acute Kidney Injury in the Early Phase of Acute Pancreatitis

Acute kidney injury (AKI) is a serious complication of acute pancreatitis (AP), which occurs in up to 70% of patients with severe AP and significantly increases the risk of mortality. At present, AKI is diagnosed based on dynamic increase in serum creatinine and decreased urine output; however, there is a need for earlier and more accurate biomarkers. The aim of the study was to review current evidence on the laboratory tests that were studied as the potential biomarkers of AKI in AP. We also briefly summarized the knowledge coming from the studies including sepsis or ICU patients since severe acute pancreatitis is associated with systemic inflammation and organ failure. Serum cystatin C and serum or urine NGAL have been shown to predict or diagnose AKI in AP; however, this evidence come from the single center studies of low number of patients. Other markers, such as urinary kidney injury molecule-1, cell cycle arrest biomarkers (tissue inhibitor metalloproteinase-2 and urine insulin-like growth factor-binding protein 7), interleukin-18, liver-type fatty acid-binding protein, or calprotectin have been studied in other populations suffering from systemic inflammatory states. In AP, the potential markers of AKI may be significantly influenced by either dehydration or inflammation, and the impact of these factors may be difficult to distinguish from kidney injury. The subject of AKI complicating AP is understudied. More studies are needed, for both exploratory (to choose the best markers) and clinical (to evaluate the diagnostic accuracy of the chosen markers in real clinical settings).

Doxycycline alleviates paraquat-induced acute lung injury by inhibiting neutrophil-derived matrix metalloproteinase 9

Paraquat (PQ), a highly toxic herbicide, selectively accumulates in the lungs and causes pulmonary damage through oxidative and inflammatory processes after intentional or accidental poisoning. The resulting acute lung injury (ALI) is characterized by neutrophil infiltration and extensive inflammation with rapid respiratory failure. However, effective therapies are lacking. We tested the hypothesis that suppressing neutrophil-derived matrix metalloproteinase 9 (MMP9) would ameliorate the inflammatory milieu and alleviate PQ-induced ALI. Lung injury was assessed in mice intratracheally injected with PQ aerosol by measuring the lung static compliance, cell count and neutrophil percentage of the bronchoalveolar lavage fluid (BALF) and lung, alveolar-capillary permeability, and histopathological lung injury scores. MMP9/2 activity was assessed by gelatin zymography, and the location of neutrophils and MMP9 in the lung was evaluated by immunofluorescence costaining. In the neutrophil depletion experiment, mice received anti-Ly6G antibody intraperitoneally; for the MMP inhibition experiment, an MMP inhibitor, doxycycline (DOX), was administered by gavage. In PQ-induced ALI, the activity of neutrophil-derived MMP9 but not MMP2 increased significantly. Neutrophil depletion reduced the inflammatory burden, improved pulmonary edema, and reduced the PQ-induced overexpression of MMP9. Consistently, oral delivery of DOX to mice decreased the overexpression of MMP9 that was activated by PQ and phenocopied the resolution of PQ-induced ALI observed after neutrophil depletion. Taken together, our results show for the first time that DOX is involved in the resolution of PQ-induced ALI via a mechanism involving reducing the activity of neutrophil-derived MMP9. We speculate that DOX may represent a novel therapeutic strategy for PQ-induced ALI.

Neutrophil Infiltration and Matrix Metalloproteinase-9 in Lacunar Infarction

We use the modified pial vessel disruption rat model to elucidate the cellular and molecular mechanisms of cavitation as it plays a role in lacunar infarction. Here we discuss the similarities between the genesis of pulmonary cavitation in various animal models and lacunar infarction in the cerebral cortex of rats. Both pathological processes involve the creation of a cavity surrounded by fibroblasts or reactive astrocytes. A crucial step in both, the lung and the cerebral cortex, appears to be the migration of neutrophils across the endothelial barrier into the parenchyma. In the lung and cerebral cortex this involves release of matrix metalloproteinase-9 (MMP-9). Inside the parenchyma neutrophils continue to release MMP-9. In both situations batimastat (BB-94) and minocycline reduce release of MMP-9 and prevent cavitation. In the cerebral cortex MMP-9 release by resident microglia plays an additional role. We therefore advance the hypothesis that cavitation in both tissues is driven by MMP-9 originating from invading neutrophils. Therapeutic intervention has to focus on these blood-borne intruder cells and specific MMP actions. Batimastat and its derivatives (marimastat, BB-1101, mCGS-27023-A, ilomastat, GM6001, CTK8G1150) are already in clinical or experimental use in humans for anti-cancer treatment, and these clinically relevant drugs could be repurposed to act as anti-inflammatory to counter neutrophil contribution to lung or cerebral cortex cavitation.

Colibactin Contributes to the Hypervirulence of pks+ K1 CC23 Klebsiella pneumoniae in Mouse Meningitis Infections

Klebsiella pneumoniae is the most common pathogen of community-acquired meningitis in Taiwan. However, the lack of a physiologically relevant meningitis model for K. pneumoniae has impeded research into its pathogenesis mechanism. Based on the core genome MLST analyses, the hypervirulent K1 K. pneumoniae strains, which are etiologically implicated in adult meningitis, mostly belong to a single clonal complex, CC23. Some K1 CC23 K. pneumoniae strains carry a gene cluster responsible for colibactin production. Colibactin is a small genotoxic molecule biosynthesized by an NRPS-PKS complex, which is encoded by genes located on the pks island. Compared to other hypervirulent K. pneumoniae which primarily infect the liver, the colibactin-producing (pks⁺) K1 CC23 strains had significant tropism toward the brain of BALB/c mice. We aimed in this study to develop a physiologically relevant meningitis model with the use of pks⁺ K1 CC23 K. pneumoniae. Acute meningitis was successfully induced in adult BALB/c male mice through orogastric, intranasal, and intravenous inoculation of pks⁺ K1 CC23 K. pneumoniae. Besides the typical symptoms of bacterial meningitis, severe DNA damages, and caspase 3-independent cell death were elicited by the colibactin-producing K1 CC23 K. pneumoniae strain. The deletion of clbA, which abolished the production of colibactin, substantially hindered K. pneumoniae hypervirulence in the key pathogenic steps toward the development of meningitis. Our findings collectively demonstrated that colibactin was necessary but not sufficient for the meningeal tropism of pks⁺ K1 CC23 K. pneumoniae, and the mouse model established in this study can be applied to identify other virulence factors participating in the development of this life-threatening disease.

Association of Matrix Metalloproteinases -7, -8 and -9 and TIMP -1 with Disease Severity in Acute Pancreatitis. A Cohort Study

Objectives

Several biomarkers for early detection of severe acute pancreatitis (SAP) have been presented. Matrix metalloproteinases (MMP) and their tissue inhibitors (TIMP) are released early in inflammation. We aimed to assess levels of MMP-7, -8, -9 and TIMP-1 in acute pancreatitis (AP) and explore their ability to detect disease severity. Our second aim was to find an association between MMPs, TIMP and creatinine.

Methods

We collected plasma samples for MMP-7, -8, -9 and TIMP-1 analyses from 176 patients presenting within 96 h from onset of acute pancreatitis (AP) symptoms. We used samples from 32 control subjects as comparison. The revised Atlanta Classification was utilised to assess severity of disease. Receiver operating characteristic curve analysis and Spearman´s Rho-test were utilised for statistical calculations.

Results

Compared with controls, patients showed higher levels of all studied markers. MMP-8 was higher in moderately severe AP than in mild AP (p = 0.005) and MMP-8, -9 and TIMP-1 were higher in severe than in mild AP (p<0.001, p = 0.005 and p = 0.019). MMP-8 detected SAP with an AUC of 0.939 [95% CI 0.894–0.984], LR+ 9.03 [5.30–15.39]. MMP-8, -9 and TIMP-1 failed to discern moderately severe AP from SAP. MMP-7 was not different between patient groups. MMP-7 and TIMP-1 correlated weakly with creatinine (Rho = 0.221 and 0.243). MMP-8 might be a useful biomarker in early detection of SAP.

The intestinal mucus layer is a critical component of the gut barrier that is damaged during acute pancreatitis

Gut barrier failure has been implicated in the progression from single-organ injury to multiple-organ failure. The unstirred mucus layer is a major component of the physiological gut barrier; its role in acute pancreatitis (AP) is not clearly defined. Rats underwent biliopancreatic duct ligation-induced AP; two controls were used: biliopancreatic duct ligation with drainage and sham duct ligation. After 4.5 h, serum and ascitic amylase activity was measured. Mucus was analyzed for reactive nitrogen intermediate-mediated damage, reactive oxygen species-induced damage, and total antioxidant capacity. Mucus coverage and villous injury were assessed histologically. Ileum permeability was measured by diffusion of a fluorescent Dextran probe. Histology and morphology of the mucus layer were validated in a mouse AP model (intraductal taurocholate plus cerulein). Biliopancreatic duct ligation increased serum α-amylase, ascitic volume, and ascitic α-amylase. Intestinal permeability was increased, which was associated with loss of the unstirred mucus layer but not villous injury. These changes correlated with increased reactive oxygen species- and- reactive nitrogen intermediate-mediated mucus damage as well as decreased mucus total antioxidant capacity but were not present in the two control groups. Using a different model of AP in mice, the finding of mucus layer disruption was recapitulated at 6 h after AP, but by 24 h, rebound hypersecretion of inspissated mucus was seen. These results support the hypothesis that damage to the unstirred mucus layer with evidence of oxidative stress occurs during AP-induced gut barrier failure.

The effect of Chaiqin Chengqi Decoction () on modulating serum matrix metalloproteinase 9 in patients with severe acute pancreatitis

OBJECTIVE

To investigate the effect of Chaiqin Chengqi Decoction (, CQCQD) on regulating serum matrix metalloproteinase 9 (MMP-9) in patients with severe acute pancreatitis (SAP).

METHODS

Thirty-five SAP patients hospitalized in West China Hospital from September 1, 2008 to February 28, 2009 were randomly assigned to two groups using a computer-derived random number sequence in a ratio of 1:1, treatment group (18 patients) and the placebo control group (17 patients). The patients in the treatment group were administered with CQCQD by gastric perfusion (50 mL/2 h) and retention enema (200 mL/6 h) for 7 days. The two groups had similar baseline information. The clinical indicators, including the initial Balthazar's computed tomography (CT) score, acute physiology and chronic health evaluation II (APACHE II) scores on 1st, 3rd, 5th and 7th day, incidences and durations of complications and the serum C-reactive protein (CRP), levels of MMP-9 on the 1st, 3rd, 5th and 7th day, were recorded and compared between the two groups.

RESULTS

The serum MMP-9, CRP and the APACHE II scores on the 3rd, 5th and 7th day in the treatment group were lower than those in the control group (P<0.05). The serum MMP-9 was positively correlated with the APACHE II score on the 1st day (r=0.430, P=0.01). The durations of acute respiratory distress syndrome (5.4±2.4 vs. 2.9±1.3), acute hepatitis (4.6±0.8 vs. 1.9±0.6) and acute heart failure (3.9±1.6 vs. 1.3±0.6, <0.05) in the control group were longer than those in the treatment group.

CONCLUSION

CQCQD could decrease the serum MMP-9 to relieve the severity of clinical symptoms and prevent the development of multiple organ dysfunction syndrome in patients with SAP.

Matrix metalloproteinase-9 in the initial injury after hepatectomy in mice

AIM: To investigate the role of matrix metalloproteinase (MMP)-9 in the pathogenesis of postoperative liver failure (PLF) after extended hepatectomy (EH).

METHODS: An insufficient volume of the remnant liver (RL) results in higher morbidity and mortality, and a murine model with 80%-hepatectomy was used. All investigations were performed 6 h after EH. Mice were first divided into two groups based on the postoperative course (i.e., the PLF caused or did not), and MMP-9 expression was measured by Western blotting. The source of MMP-9 was then determined by immunohistological stainings. Tissue inhibitor of metalloproteinase (TIMP)-1 is the endogenous inhibitor of MMP-9, and MMP-9 behavior was assessed by the experiments in wild-type, MMP-9(-/-) and TIMP-1(-/-) mice by Western blotting and gelatin zymography. The behavior of neutrophils was also assessed by immunohistological stainings. An anti-MMP-9 monoclonal antibody and a broad-spectrum MMP inhibitor were used to examine the role of MMP-9.

RESULTS: Symptomatic mice showed more severe PLF (histopathological assessments: 2.97 ± 0.92 vs 0.11 ± 0.08, P < 0.05) and a higher expression of MMP-9 (71085 ± 18274 vs 192856 ± 22263, P < 0.01). Nonnative leukocytes appeared to be the main source of MMP-9, because MMP-9 expression corresponding with CD11b positive-cell was observed in the findings of immunohistological stainings. In the histopathological findings, the PLF was improved in MMP-9(-/-) mice (1.65% ± 0.23% vs 0.65% ± 0.19%, P < 0.01) and it was worse in TIMP-1(-/-) mice (1.65% ± 0.23% vs 1.78% ± 0.31%, P < 0.01). Moreover, neutrophil migration was disturbed in MMP-9(-/-) mice in the immunohistological stainings. Two methods of MMP-9 inhibition revealed reduced PLF, and neutrophil migration was strongly disturbed in MMP-9-blocked mice in the histopathological assessments (9.6 ± 1.9 vs 4.2 ± 1.2, P < 0.05, and 9.9 ± 1.5 vs 5.7 ± 1.1, P < 0.05).

CONCLUSION: MMP-9 is important for the process of PLF. The initial injury is associated with MMP-9 derived from neutrophils, and MMP-9 blockade reduces PLF. MMP-9 may be a potential target to prevent PLF after EH and to overcome an insufficient RL.

Intestinal microbiota, probiotics and mental health: from Metchnikoff to modern advances: part III - convergence toward clinical trials

Rapid scientific and technological advances have allowed for a more detailed understanding of the relevance of intestinal microbiota, and the entire body-wide microbiome, to human health and well-being. Rodent studies have provided suggestive evidence that probiotics (e.g. lactobacillus and bifidobacteria) can influence behavior. More importantly, emerging clinical studies indicate that the administration of beneficial microbes, via supplementation and/or fecal microbial transplant (FMT), can influence end-points related to mood state (glycemic control, oxidative status, uremic toxins), brain function (functional magnetic resonance imaging fMRI), and mental outlook (depression, anxiety). However, despite the advances in the area of gastro-biological psychiatry, it becomes clear that there remains an urgent need to explore the value of beneficial microbes in controlled clinical investigations. With the history explored in this series, it is fair to ask if we are now on the cusp of major clinical breakthroughs, or are we merely in the quicksand of Autointoxication II?

Toll-like receptor 4 signaling pathway and pancreatitis

The pathogenesis of pancreatitis has long been a hot topic in basic and clinical research but is still not fully clarified. Toll-like receptor 4 (TLR4) recognizes the lipopolysaccharide (LPS) of Gram-negative bacteria and stimulates the synthesis and release of inflammatory cytokines through activation of the NF-κB signaling pathway, which ultimately results in inflammatory responses that involve multiple organs. Animal and clinical studies have shown that the TLR4 signal pathway plays an important role in the development of tissue injury during acute pancreatitis (AP) and up-regulation of TLR4 and the TLR4 signaling pathway contributes to the development of multiple organ dysfunction syndrome (MODS) associated with severe acute pancreatitis (SAP) by increasing proinflammatory cytokines. Therefore, further studies are required to clarify the role of the TLR 4 signaling pathway in the pathogenesis of pancreatitis to explore novel methods for treating this disease.

Neutrophil-derived matrix metalloproteinase-9 is a potent activator of trypsinogen in acinar cells in acute pancreatitis

MMPs are generally considered to regulate degradation and remodeling of the ECM. Convincing data also implicate a role for MMPs in inflammatory conditions, such as AP, although the mechanisms are not known. The aim of this study was to define the role of MMPs in regulating activation of trypsinogen and tissue damage in AP, which was induced by infusion of taurocholate into the pancreatic duct in mice. A broad-spectrum MMP inhibitor (BB-94) and MMP-9 gene-deficient mice were used. Neutrophil secretions and rMMP-9 were used to stimulate trypsinogen activation in isolated acinar cells. Taurocholate challenge increased serum amylase, neutrophil infiltration, MIP-2 (CXCL2) formation, trypsinogen activation, and tissue damage in the pancreas. Treatment with the broad-spectrum inhibitor of MMPs, BB-94, markedly reduced activation of trypsinogen, levels of CXCL2, infiltration of neutrophils, and tissue damage in AP. Taurocholate challenge increased serum levels of MMP-9 but not MMP-2. Taurocholate-induced amylase levels, neutrophil accumulation, production of CXCL2, trypsinogen activation, and tissue damage in the pancreas were abolished in MMP-9-deficient mice. Moreover, secretions from activated neutrophils isolated from WT but not from MMP-9-deficient animals stimulated trypsinogen activation in acinar cells. Notably, rMMP-9 greatly enhanced activation of trypsinogen in acinar cells. These findings demonstrate that neutrophil-derived MMP-9 is a potent activator of trypsinogen in acinar cells and regulates pathological inflammation and tissue damage in AP.

Chymase inhibition reduces infarction and matrix metalloproteinase-9 activation and attenuates inflammation and fibrosis after acute myocardial ischemia/reperfusion

Chymase is activated after acute myocardial ischemia/reperfusion (AMI-R) and is associated with an early activation of matrix metalloproteinase-9 (MMP-9), which increases infarct size after experimental AMI, and late fibrosis. We assessed the effect of chymase inhibition on myocardial protection and early signs of fibrosis after AMI-R. Fourteen pigs underwent AMI-R and received intravenously either vehicle (V; n = 7) or chymase inhibitor (CM; n = 7). Separately, rat myocardial fibroblast was incubated with vehicle (n = 4), low-dose chymase (n = 4), high-dose chymase (n = 4), or high-dose chymase plus chymase inhibitor (n = 4). Infarct size (V, 41 ± 5; CM, 24 ± 5; P < 0.01) and serum troponin T (P = 0.03) at the end of reperfusion were significantly reduced in CM. Chymase activity in both the area at risk (AAR) (P = 0.01) and nonischemic area (P = 0.02) was significantly lower in CM. Myocardial levels of pro, cleaved, and cleaved/pro-MMP-9 in the AAR were significantly lower in CM than V (P < 0.01, < 0.01, and = 0.02, respectively), whereas phospho-endothelial nitric-oxide synthase (eNOS) (P < 0.01) and total eNOS (P = 0.03) were significantly higher in CM. Apoptotic cells (P = 0.05), neutrophils (P < 0.05), and MMP-9-colocalizing mast cells (P < 0.05) in the AAR were significantly reduced in CM. Interleukin-18 (P < 0.05) and intercellular adhesion molecule-1 (P < 0.05) mRNA levels were significantly lower in CM. In cultured cardiac fibrosis, Ki-67-positive cells were significantly higher in the high-dose chymase groups (P < 0.03). This study demonstrates that chymase inhibition plays crucial roles in myocardial protection related to MMP-9, inflammatory markers, and the eNOS pathway. It may also attenuate fibrosis induced by activated chymase after AMI-R.

Role of neutrophils in the activation of trypsinogen in severe acute pancreatitis

The relationship between inflammation and proteolytic activation in pancreatitis is an unresolved issue in pancreatology. The purpose of this study was to define the influence of neutrophils on trypsinogen activation in severe AP. Pancreatitis was induced by infusion of taurocholate into the pancreatic duct in C57BL/6 mice. For neutrophil depletion, an anti-Gr-1 antibody was administered before pancreatitis induction. Administration of the anti-Gr-1 antibody reduced circulating neutrophils by 97%. Pancreatic TAP and serum amylase levels increased 2 h and 24 h after induction of pancreatitis. Neutrophil depletion reduced pancreatic TAP and serum amylase levels at 24 h but not at 2 h after pancreatitis induction. Pancreatic MPO and infiltration of neutrophils, as well as MIP-2 levels, were increased 24 h after taurocholate infusion. Two hours after taurocholate administration, no significant pancreatic infiltration of neutrophils was observed. Injection of the anti-Gr-1 antibody abolished MPO activity, neutrophil accumulation, and MIP-2 levels, as well as acinar cell necrosis, hemorrhage, and edema in the pancreas at 24 h. Moreover, taurocholate-provoked tissue damage and MPO activity in the lung were normalized by neutrophil depletion. Intravital fluorescence microscopy revealed a 97% reduction of leukocytes in the pancreatic microcirculation after administration of the anti-Gr-1 antibody. Our data demonstrate that initial trypsinogen activation is independent of neutrophils, whereas later activation is dependent on neutrophils in the pancreas. Neutrophils are critical in mediating pancreatic and lung tissue damage in severe AP.

Early production of IL-22 but not IL-17 by peripheral blood mononuclear cells exposed to live Borrelia burgdorferi: the role of monocytes and interleukin-1

If insufficiently treated, Lyme borreliosis can evolve into an inflammatory disorder affecting skin, joints, and the CNS. Early innate immunity may determine host responses targeting infection. Thus, we sought to characterize the immediate cytokine storm associated with exposure of PBMC to moderate levels of live Borrelia burgdorferi. Since Th17 cytokines are connected to host defense against extracellular bacteria, we focused on interleukin (IL)-17 and IL-22. Here, we report that, despite induction of inflammatory cytokines including IL-23, IL-17 remained barely detectable in response to B. burgdorferi. In contrast, T cell-dependent expression of IL-22 became evident within 10 h of exposure to the spirochetes. This dichotomy was unrelated to interferon-γ but to a large part dependent on caspase-1 and IL-1 bioactivity derived from monocytes. In fact, IL-1β as a single stimulus induced IL-22 but not IL-17. Neutrophils display antibacterial activity against B. burgdorferi, particularly when opsonized by antibodies. Since neutrophilic inflammation, indicative of IL-17 bioactivity, is scarcely observed in Erythema migrans, a manifestation of skin inflammation after infection, protective and antibacterial properties of IL-22 may close this gap and serve essential functions in the initial phase of spirochete infection.

Significance of chymase-dependent matrix metalloproteinase-9 activation on indomethacin-induced small intestinal damages in rats

The side effects of nonsteroidal anti-inflammatory drugs (NSAIDs) include gastrointestinal damage not only in the stomach but also in the small intestine. Chymase converts promatrix metalloproteinase-9 to matrix metalloproteinase (MMP)-9, which plays an important role in NSAID-induced gastric damage, but it has been unclear whether chymase-dependent MMP-9 activation is involved in the NSAID-induced small intestinal damage. To clarify the involvement of chymase-dependent MMP-9 activation on NSAID-induced small intestinal damage, the effect of a chymase inhibitor, 2-[4-(5-fluoro-3-methylbenzo[b]thiophen-2-yl)sulfonamido-3-methanesulfonylphenyl] thiazole-4-carboxylic acid (TY-51469), on indomethacin-induced small intestinal damage in rats was evaluated. Until 6 h after oral administration of indomethacin in rats, intestinal MMP-9 activity was unchanged compared with normal rats, but significant increases in MMP-9 activity were observed 12 and 24 h after indomethacin administration. Significant increases in the small intestinal damage score were also observed 12 and 24 h after indomethacin administration. In the extract from the small intestine 24 h after indomethacin administration, the MMP-9 activation was significantly attenuated by TY-51469. Intraperitoneal injection of TY-51469 (10 mg/kg) 3 h before indomethacin administration significantly attenuated the MMP-9 activity in the small intestine compared with placebo treatment. Myeloperoxidase activity, which indicates accumulation of neutrophils, was significantly increased in the small intestine in the placebo-treated rats, but its activity was significantly attenuated by TY-51469 treatment. The area of small intestinal damage was also significantly ameliorated by TY-51469 treatment. These findings suggest that chymase-dependent MMP-9 activation has a significant role in indomethacin-induced small intestinal damage in rats.