Role of TGF-beta1, extracellular matrix, and matrix metalloproteinase in the healing process of the pancreas after induction of acute necrotizing pancreatitis using arginine in rats

Serum Biomarkers of Nociceptive and Neuropathic Pain in Chronic Pancreatitis

Debilitating abdominal pain is a common symptom affecting most patients with chronic pancreatitis (CP). There are multiple underlying mechanisms that contribute to CP-related pain, which makes successful treatment difficult. The identification of biomarkers for subtypes of pain could provide viable targets for nonopioid interventions and the development of mechanistic approaches to pain management in CP. Nineteen inflammation- and nociception-associated proteins were measured in serum collected from 358 subjects with definite CP enrolled in PROspective Evaluation of Chronic Pancreatitis for EpidEmiologic and Translational StuDies, a prospective observational study of pancreatitis in US adult subjects. First, serum levels of putative biomarkers were compared between CP subjects with and without pain. Only platelet-derived growth factor B (PDGF-B) stood out, with levels significantly higher in the CP pain group as compared to subjects with no pain. Subjects with pain were then stratified into 4 pain subtypes (Neuropathic, Nociceptive, Mixed, and Unclassified). A comparison of putative biomarker concentration among 5 groups (no pain and 4 pain subtypes) identified unique proteins that were correlated with pain subtypes. Serum transforming growth factor beta 1 (TGFβ1) level was significantly higher in the Nociceptive pain group compared to the No pain group, suggesting that TGFβ1 may be a biomarker for nociceptive pain. The Neuropathic pain only group was too small to detect statistical differences. However, glycoprotein 130 (GP130), a coreceptor for interleukin 6, was significantly higher in the Mixed pain group compared to the groups lacking a neuropathic pain component. These data suggest that GP130 may be a biomarker for neuropathic pain in CP. PERSPECTIVE: Serum TGFβ1 and GP130 may be biomarkers for nociceptive and neuropathic CP pain, respectively. Preclinical data suggest inhibiting TGFβ1 or GP130 reduces CP pain in rodent models, indicating that additional translational and clinical studies may be warranted to develop a precision medicine approach to the management of pain in CP.

Evaluation of an antibacterial peptide-loaded amniotic membrane/silk fibroin electrospun nanofiber in wound healing

Antimicrobial peptides (AMPs) are among the compounds that have significant potential to deal with infectious skin wounds. Using wound dressings or skin scaffolds containing AMPs can be an effective way to overcome infections caused by antibiotic-resistant strains. In this study, we developed an amniotic membrane-based skin scaffold using silk fibroin to improve mechanical properties and CM11 peptide as an antimicrobial peptide. The peptide was coated on the scaffold using the soaking method. The fabricated scaffold was characterised by SEM and FTIR, and their mechanical strength, biodegradation, peptide release, and cell cytotoxicity analyses were performed. Then, their antimicrobial activity was measured against antibiotic-resistant strains of Pseudomonas aeruginosa and Staphylococcus aureus. The in vivo biocompatibility of this scaffold was evaluated by subcutaneously implanting it under the skin of the mouse and counting lymphocytes and macrophages in the implanted area. Finally, the regenerative ability of the scaffold was analyzed in the mouse full-thickness wound model by measuring the wound diameter, H&E staining, and examining the expression rate of genes involved in the wound healing process. The developed scaffolds exerted an inhibiting effect on the bacteria growth, indicating their proper antimicrobial property. In vivo biocompatibility results showed no significant count of macrophages and lymphocytes between the test and control groups. The wound closure rate was significantly higher in the wound covered with fibroin electrospun-amniotic membrane loaded with 32 μg/mL CM11, where the relative expression rates of collagen I, collagen III, TGF-β1 and TGF-β3 were higher compared with the other groups.

Transforming growth factor-β in pancreatic diseases: Mechanisms and therapeutic potential

Pancreatic diseases, such as acute pancreatitis, chronic pancreatitis, and pancreatic cancer, are common gastrointestinal diseases resulting in the development of local and systemic complications with a high risk of death. Numerous studies have examined pancreatic diseases over the past few decades; however, the pathogenesis remains unclear, and there is a lack of effective treatment options. Recently, emerging evidence has suggested that transforming growth factor beta (TGF-β) exerts controversial functions in apoptosis, inflammatory responses, and carcinogenesis, indicating its complex role in the pathogenesis of pancreas-associated disease. Therefore, a further understanding of relevant TGF-β signalling will provide new ideas and potential therapeutic targets for preventing disease progression. This is the first systematic review of recent data from animal and human clinical studies focusing on TGF-β signalling in pancreas damage and diseases. This information may aid in the development of therapeutic agents for regulating TGF-β in this pathology to prevent or treat pancreatic diseases.

Galunisertib (LY2157299), a transforming growth factor-β receptor I kinase inhibitor, attenuates acute pancreatitis in rats

Galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-β receptor I (TGF-βRI), is the only known TGF-β pathway inhibitor. In the present study, we investigated the effect of galunisertib on taurocholate (TAC)-induced acute pancreatitis (AP) in rats, and the role of TGF-β and NF-κB signaling pathways. AP was induced by infusion of TAC into the pancreatic duct of Sprague-Dawley male rats (n=30). The rats (220±50 g) were administered galunisertib intragastrically [75 mg·kg^-1·day^-1 for 2 days (0 and 24 h)]. Serum IL-1β, IL-6, TNF-α, amylase (AMY), lipase (LIP), and myeloperoxidase (MPO) levels were measured by ELISA. NF-κB activity was detected by electrophoretic mobility shift assay (EMSA); NF-κBp65 and TGF-β1 proteins, as well as TGF-βRI and p-Smad2/3 proteins, were detected by western blot assay. Cell apoptosis was detected by TUNEL assay. H&E staining was used to evaluate the histopathological alterations of the pancreas. Galunisertib treatment attenuated the severity of AP and decreased the pancreatic histological score. In addition, number of apoptotic cells were significantly increased in the galunisertib-treated group (16.38±2.26) than in the AP group (8.14±1.27) and sham-operated group (1.82±0.73; P<0.05 and P<0.01, respectively). Galunisertib decreased the expression levels of TGF-βRI and p-Smad2/3 and inhibited NF-κB activation and p65 translocation compared with the sham-operated group. Furthermore, serum IL-1β, IL-6, TNF-α, AMY and LIP levels and tissue MPO activity were significantly decreased in the galunisertib-treated group. Our data demonstrate that galunisertib attenuates the severity of TAC-induced experimental AP in rats by inducing apoptosis in the pancreas, inhibiting the activation of TGF-β signals and NF-κB as well as the secretion of pro-inflammatory cytokines.

Acute Effects of Transforming Growth Factor-β1 on Neuronal Excitability and Involvement in the Pain of Rats with Chronic Pancreatitis

Background/Aims

This study was to investigate whether transforming growth factor-β1 (TGF-β1) plays a role in hyperalgesia in chronic pancreatitis (CP) and the underlying mechanisms.

Methods

CP was induced in male adult rats by intraductal injection of trinitrobenzene sulfonic acid (TNBS). Abdominal hyperalgesia was assessed by referred somatic behaviors to mechanical stimulation of rat abdomen. Dil dye injected into the pancreas was used to label pancreas-specific dorsal root ganglion (DRG) neurons. Whole cell patch clamp recordings and calcium imaging were performed to examine the effect of TGF-β1 on acutely isolated pancreas-specific DRG neurons. Western blot analysis was carried out to measure the expression of TGF-β1 and its receptors.

Results

TNBS injection significantly upregulated expression of TGF-β1 in the pancreas and DRGs, and TGF-β1 receptors in DRGs (T9-T13) in CP rats. Intrathecal injection of TGF-β receptor I antagonist SB431542 attenuated abdominal hyperalgesia in CP rats. TGF-β1 application depolarized the membrane potential and caused firing activity of DRG neurons. TGF-β1 application also reduced rheobase, hyperpolarized action potential threshold, and increased numbers of action potentials evoked by current injection of pancreas-specific DRG neurons. TGF-β1 application also increased the concentration of intracellular calcium of DRG neurons, which was inhibited by SB431542. Furthermore, intrathecal injection of TGF-β1 produced abdominal hyperalgesia in healthy rats.

Conclusions

These results suggest that TGF-β1 enhances neuronal excitability and increases the concentration of intracellular calcium. TGF-β1 and its receptors are involved in abdominal hyperalgesia in CP. This and future study might identify a potentially novel target for the treatment of abdominal pain in CP.

Influence of matrix metalloproteinase-1 gene -1607 (1G/2G) (rs1799750) promoter polymorphism on circulating levels of MMP-1 in chronic pancreatitis

This study investigated the role of -1607 (1G/2G) (rs1799750) polymorphism of the MMP-1 gene in chronic pancreatitis. We genotyped 100 patients with chronic pancreatitis and 100 control subjects using tetra-primer ARMS-PCR followed by agarose gel electrophoresis. Serum levels of MMP-1 were determined by Elisa. Statistical analysis was applied to test the significance of the results. The genotypic and allelic distribution varied significantly between the disease group and the control subjects [OD = 1.981 (1.236-3.181), p = 0.004]. MMP-1 levels were higher in subjects homozygous for the 2G allele than in subjects with the 1G allele. The present study revealed a significant association of the MMP-1 -1607 1G/2G (rs1799750) gene promoter polymorphism with chronic pancreatitis, and it can be considered a biological marker in the etiology of chronic pancreatitis.

Plasma TGF-β1, MMP-1 and MMP-3 Levels in Chronic Pancreatitis

Chronic pancreatitis (CP) presenting clinically with upper abdominal pain, as well as exocrine and endocrine insufficiencies, is characterized by irreversible morphological and functional alterations in the pancreas. The objective of the present study is to investigate the plasma levels of transforming growth factor-β 1 (TGF-β1), matrix metalloproteinases MMP-1 (collagenase) and MMP-3 (stromelysin) in CP. A total of 71 CP patients and 100 control subjects were considered for the study. Plasma levels of TGF-β1, MMP-1 and MMP-3 were determined by enzyme-linked immunosorbent assay in patients and control subjects. The plasma levels of TGF-β1 and MMP-1 were significantly elevated in patients compared to control group (*P = 0.0301, **P < 0.0001). However, there was no significant difference in the plasma levels of MMP-3 between patients and controls (P = 0.3756). The elevated levels of TGF-β1 and MMP-1 may influence the inflammatory reactions by enhancing the pancreatic stellate cell activation and deposition of extracellular matrix resulting in pancreatic fibrosis. Thus, the present study highlights the role of fibrogenic cytokine marker TGF-β1 and matrix metalloproteinases in the pathogenesis of CP.

Rosiglitazone promotes pancreatic regeneration in experimental model of acute pancreatitis

Acute pancreatitis is an inflammatory disease of the pancreas caused by release of activated digestive enzymes in the pancreas. A number of therapeutic options have been explored for acute pancreatitis, but none has been unambiguously proven to be effective. Rosiglitazone has been shown to be efficacious in acute pancreatitis; thus, the present study was planned to evaluate the effect of rosiglitazone on pancreatic regeneration. Pancreatitis was induced by l-arginine in rats which were divided into three groups: cholecystokinin (CCK-8), rosiglitazone and vehicle. Rats were sacrificed at four time points after induction of pancreatitis i.e. 24h, day 3, day 14 and day 28 for determination of biochemical parameters and histological examination. Rate of DNA synthesis, immunohistochemistry and RT-PCR were performed at day 3 and day 7. Drug administration was started 2h after last L-arginine injection and continued till the day of sacrifice. The lower levels of enzyme in rosiglitazone-treated group compared to vehicle group proved the efficacy of rosiglitazone treatment in reducing severity of acute pancreatitis. The nucleic acid content and rate of DNA synthesis were significantly higher in rosiglitazone group indicating promotion of pancreatic regeneration. The histopathological score were lower in rosiglitazone group. Rosiglitazone treatment promoted pancreatic regeneration after acute injury. Currently, only symptomatic treatment is available, regeneration of pancreatic tissue can be a future strategy in the management of acute pancreatitis. Further studies are required to support the findings of the present study.

Melatonin treatment is beneficial in pancreatic repair process after experimental acute pancreatitis

Current treatment options for acute pancreatitis are supportive and symptomatic. Due to lack of agents targeting the underlying pathophysiology a large amount of experimental work is going on to identify novel therapeutic agents. The present study was carried out to explore if melatonin can modulate the spontaneous regeneration process of the pancreas after experimentally induced acute pancreatitis. Rats were given two i.p. injections of l-arginine in a dose of 200mg/100g at an interval of 1h for induction of pancreatitis. After this rats were randomly divided into three groups i.e. saline, CCK-8 and melatonin. Drug treatment was started 2h after the last l-arginine injection and continued till the day of sacrifice. An additional only saline treated control group was included for comparison. Animals in each group were sacrificed at 24h, days 3, 14 and 28 after pancreatitis induction for determination of biochemical parameters (serum amylase, lipase and IL-10 and pancreatic amylase, total proteins and nucleic acid content) and histological examination. For rate of DNA synthesis and immunohistochemical studies animals were sacrificed at day 3 and day 7. Melatonin treatment was found to be beneficial in acute pancreatitis. Severity of acute pancreatitis was significantly reduced in melatonin group. Nucleic acid content, rate of DNA synthesis, pancreatic proteins and pancreatic amylase content were significantly improved. Histopathological examination showed significantly lower total scores in melatonin group. Results of melatonin group were comparable to that of positive control, CCK-8 group. Thus melatonin treatment was found to promote the spontaneous regeneration process of pancreatic tissue.

Expression of extracellular matrix proteins in the vocal folds and bone marrow derived stromal cells of rats

Vocal fold scarring remains a therapeutic challenge. Our research group has indicated that bone marrow-derived stromal cells (BSCs) may have therapeutic potential in restoration of injured vocal folds. However, it is still unclear how BSCs restore the viscoelasticity of vocal fold mucosa. Since a feature of vocal fold scarring is the disorganization of the extracellular matrix (ECM), it is important to understand how BSCs produce ECM. The present study aimed to clarify ECM gene expression in BSCs, and also examined the effects of hepatocyte growth factor (HGF) on this expression. BSCs obtained from the femurs of four Sprague-Dawley rats were cultured with or without HGF. The mRNA expression of ECM components (type I procollagen, decorin, Has2, CD44, MMP-1, and GAPDH) were examined in cultured BSCs and the vocal fold mucosa by the reverse transcription-polymerase chain reaction (RT-PCR). The mRNA expression of Has2 and MMP-1 was significantly stronger in BSCs than in the vocal folds (P < 0.05). Expression of Has2 in BSCs was significantly increased by the administration of HGF (P < 0.05). There was no significant difference in the gene expression of other ECM molecules between BSCs and vocal fold mucosa. Increased expression of Has2 and MMP-1 genes from BSCs may have a positive potential in the treatment of vocal fold scarring.

Preferential increase of extracellular matrix expression relative to transforming growth factor beta1 in the pancreas during the early stage of acute hemorrhagic pancreatitis in rats

OBJECTIVES

To elucidate the role of transforming growth factor (TGF) beta1 and extracellular matrix (ECM) after acute necrotizing pancreatitis, we studied the regulation of TGF-beta1 and ECM after induction of pancreatitis.

METHODS

We examined the serial changes of levels of plasma TGF-beta1 by enzyme-linked immunoassay and expression of TGF-beta1 and ECM by Northern and Western blot analyses, respectively, in the pancreas after induction of sodium taurocholate-induced acute pancreatitis.

RESULTS

Plasma total (active and inactive) TGF-beta1 levels at 3 hours after induction of pancreatitis were significantly increased compared with baseline values. The levels of TGF-beta1 messenger RNA (mRNA) were unaltered by day 2. Levels of fibronectin mRNA at 3 hours after induction of pancreatitis were already higher than the baseline values. Latency-associated peptide-TGF-beta1 showed a peak on day 7. Thus, the expression of ECM mRNA increased earlier than that of TGF-beta1 mRNA.

CONCLUSIONS

These results suggest that the increase in plasma TGF-beta1 concentration probably results from the elevated secretion of TGF-beta1 from several cells and/or the redistribution of TGF-beta1 protein and that the increase in expression of ECM probably is associated with the activation of TGF-beta1. It is conceivable that both increased plasma concentration and focal activation of TGF-beta1 play an important role in ECM production during the early stage of acute pancreatitis.

Vocal fold tissue repair in vivo using a synthetic extracellular matrix

Chemically modified hyaluronic acid (HA)-gelatin hydrogels have been documented to support attachment, growth, and proliferation of fibroblasts in vitro and to facilitate repair and engineering of tissues in vivo. The objective of this study was to determine the optimal composition of a synthetic extracellular matrix (sECM) that would promote wound repair and induce tissue regeneration in a rabbit vocal fold wound healing model. The sECM was formed using a thiol-modified semisynthetic glycosaminoglycan (GAG) derived of HA (Carbylan-SX) mixed with a thiolated gelatin derivative, co-cross-linked with poly(ethylene glycol) diacrylate to form Carbylan-GSX. Forty rabbits underwent vocal fold biopsy bilaterally. Rabbits were treated with Carbylan-SX, which lacks gelatin, or with Carbylan-GSX with different gelatin concentrations (2.5%, 5%, 10%, and 20%) via unilateral injection of the vocal fold at the time of biopsy. Saline was injected in the contralateral vocal fold as a control. Three weeks after biopsy and injection, animals were euthanized and mRNA levels of procollagen type 1, fibronectin, transforming growth factor beta 1 (TGF-beta1), fibromodulin, HA synthase 2, hyaluronidase 2, and tissue biomechanics were evaluated. Hyaluronidase mRNA levels were found to be significantly elevated in for Carbylan-GSX 20% w/w gelatin compared to controls. Both Carbylan-SX and Carbylan-GSX significantly improved tissue elasticity and viscosity. Carbylan-GSX containing 5% w/w gelatin showed the most promise as a scaffold material for vocal fold tissue regeneration.

Effect of early administration of exogenous basic fibroblast growth factor on acute edematous pancreatitis in rats

AIM

To observe the therapeutic effect of early administration of exogenous Basic fibroblast growth factor (bFGF) on acute edematous pancreatitis (AEP) in rats.

METHODS

Thirty male Sprague-Dawley rats were randomly divided into three (n = 10): normal control group (group I), AEP group (group II) and AEP with bFGF treatment group (group III). AEP was induced by subcutaneous injection of cerulein (5.5 microg/kg and 7.5 microg/kg) at 1 h interval into rats of groups II and III. Three hours after induction of AEP, 100 microg/kg bFGF was administrated intraperitoneally for 1 h to group III rats. For test of DNA synthesis in acinar cells, 5-bromo-2'-deoxyuridine (BrdU) labeling solution was intraperitoneally injected into the rats of groups II and III 24 h after bFGF treatment. The changes in serum amylase, lipase, pancreatic tissue wet/dry ratio were detected.

RESULTS

In bFGF treatment group, there was a significant decrease in the volume of serum amylase, lipase and the pancreatic wet/dry weight ratio(1383.0+/-94.6 U/L, 194.0+/-43.6 U/L, 4.32+/-0.32) compared to AEP group (3464+/-223.7 U/L, 456+/-68.7 U/L, 6.89+/-0.47) (P < 0.01), and no significant difference was found between bFGF treatment and control group (1289+/-94.0 U/L, 171+/-23.4 U/L, 4.12+/-0.26, P > 0.05). The inflammatory changes such as interstitial edema, polymorphonuclear neutrophils (PMNs) and vacuolization were significantly ameliorated compared to AEP group (P < 0.01). A small number of BrdU-labeled nuclei were observed in acinar cells of AEP rats (1.8+/-0.3 nuclei/microscopic field, n = 10) while diffuse BrdU-labeled nuclei were found in bFGF-treated rats (18.9+/-1.4 nuclei/microscopic field, n = 10) (P < 0.01). Immunohistochemical study showed increased DNA synthesis in pancreatic acinar cells.

CONCLUSION

Early administration of exogenous bFGF has significant therapeutic effect on cerulein-induced acute edematous pancreatitis in rats. Its mechanism is related to the amelioration of inflammation and facilitation of pancreatic regeneration.

Differential kinetics of plasma CD105 and transforming growth factor beta expression early in human acute pancreatitis

OBJECTIVES

The interaction of transforming growth factor beta (TGF-beta) with CD105 (endoglin) is an essential step in the maintenance of endothelial cell quiescence. The importance of this interaction during the critical early phases of acute pancreatitis is unknown. This study explores patterns of expression of CD105 and TGF-beta in plasma during human acute pancreatitis.

METHODS

Forty-one patients with a clinical diagnosis of acute pancreatitis constitute the study population. Venous blood samples were taken at admission and on the fifth day. Enzyme-linked immunosorbent assay was performed for CD105, TGF-beta1, TGF-beta3, CD105/TGF-beta1, and CD105/TGF-beta3 complexes.

RESULTS

TGF-beta1 levels were significantly elevated on admission in the acute pancreatitis group compared with controls and were further elevated in delayed samples. In contrast, admission CD105 levels were similar to those in controls, but in delayed samples, there was a significant reduction in CD105. Levels of TGF-beta3, CD105/TGF-beta1, and CD105/TGF-beta3 did not differ between groups.

CONCLUSIONS

This is the first report to investigate the interplay between plasma expression of CD105, TGF-beta1, TGF-beta3, and ligand complexes in acute pancreatitis. The results of this study confirm previous findings that increased expression of TGF-beta1 is a feature of severe acute pancreatitis. The absence of a parallel elevation in CD105 or CD105/TGF-beta ligand complexes is previously unreported and may suggest that angiogenesis mediated by the interaction between CD105 and TGF-beta is not an early feature of this disease.

Persistent destruction of the basement membrane of the pancreatic duct contributes to progressive acinar atrophy in rats with experimentally induced pancreatitis

BACKGROUND AND AIMS

The imbalance between synthesis and degradation of extracellular matrix (ECM) proteins is a characteristic feature in chronic pancreatitis. We evaluated the relationship between type IV collagen structure in the basement membrane (BM) and the development of acinar atrophy or the regeneration from acinar injury.

METHODS

Three different models of pancreatitis were induced in rats by repetitive intraperitoneal injections of 500 mg/100 g body weight of arginine (Arg) or 20 microg/kg body weight of caerulein (Cn) or a single retrograde intraductal infusion of 40 microL/100 g body weight of 3% sodium taurocholate (NaTc). We examined the changes in type IV collagen structure by immunostaining, and the serial changes in the gelatinolytic activity of pro- and active matrix metalloproteinase-2 by zymography in these models of pancreatitis.

RESULTS

The pancreas appeared to be histologically normal on day 35 after the first intraperitoneal Cn injection and on day 42 after intraductal infusion of NaTc, whereas 85% to 90% of acinar tissue was replaced by fatty tissue and dilated pancreatic ducts on day 54 after the first intraperitoneal Arg injection. Immunoreactivity for type IV collagen appeared as a discontinuous line along the BM of ducts, vessels, tubular complexes, and acinar cells on day 40 in Arg-induced pancreatitis, whereas it was detected as a continuous line along the BM on day 35 in Cn-induced pancreatitis and on day 42 in NaTc-induced pancreatitits. Gelatinolytic activity of active MMP-2 increased significantly from day 13 to day 40 after the first intraperitoneal Arg injection, whereas it decreased to the baseline level on day 35 after the first intraperitoneal Cn injection and on day 42 after intraductal infusion of NaTc.

CONCLUSIONS

Our findings indicate that a long-term increase in gelatinolytic activity of active MMP-2 in Arg-induced pancreatitis causes continuous disorganization of type IV collagen in the BM and progressive acinar atrophy, whereas a transient increase in gelatinolytic activity of active MMP-2 is involved in the regeneration of type IV collagen structure in the BM and recovery from acinar injury.

L-arginine-induced experimental pancreatitis

Despite medical treatment, the lethality of severe acute pancreatitis is still high (20%-30%). Therefore, it is very important to find good animal models to characterise the events of this severe disease. In 1984, Mizunuma et al^[1] developed a new type of experimental necrotizing pancreatitis by intraperitoneal administration of a high dose of L-arginine in rats. This non-invasive model is highly reproducible and produces selective, dose-dependent acinar cell necrosis. Not only is this a good model to study the pathomechanisms of acute necrotizing pancreatitis, but it is also excellent to observe and influence the time course changes of the disease. By writing this review we iluminate some new aspects of cell physiology and pathology of acute necrotizing pancreatitis. Unfortunately, the reviews about acute experimental pancreatitis usually did not discuss this model. Therefore, the aim of this manuscript was to summarise the observations and address some challenges for the future in L-arginine-induced pancreatitis.

Ramipril treatment suppresses islet fibrosis in Otsuka Long–Evans Tokushima fatty rats

We evaluated whether ramipril, one of long-acting ACEIs, has a direct effect on pancreas islets in animal model of type 2 diabetes. OLETF rats were treated with ramipril for 24 weeks. We assessed the body weight, glucose tolerance, and the amount of islet fibrosis. RT-PCR and Western blot analysis of transforming growth factor-beta with its downstream signals were performed from the pancreas. Ramipril treatment remarkably reduced weight gain and the area under the curve of glucose. Islet fibrosis and the expression of TGF-beta with its downstream signal molecules were significantly reduced in the pancreas of ramipril-treated group than in control and paired-feeding group. These beneficial effects of ramipril might be related to the downregulation of TGF-beta and its downstream signals in OLETF rats. To our knowledge, this is the first report suggesting the potential effect of ramipril on the prevention of islet destruction by fibrosis in the animal model of type 2 diabetes mellitus.

Vessel injury and capillary leak

OBJECTIVE

To understand the mechanism of pathologic capillary leak in the critically ill patient.

DESIGN

Review of normal and altered physiology of the microvasculature. Review of recent literature describing pathogenesis, mediators, and interventions influencing capillary leak and microvascular repair.

SETTING

In vitro and in vivo studies, the latter including animal and human subjects.

MEASUREMENTS AND MAIN RESULTS

Capillary leak with resultant edema develops in the critical care setting on the basis of perturbations in Starling's equation, primarily as a result of increased capillary permeability to larger molecules. This process is most likely fueled by inflammatory mediators or mechanical stress. Attempts to prevent or treat this process remain largely unsuccessful; resuscitation is more often symptomatic than therapeutic. Models of microvascular repair focus on discrete injury and may not be applicable to the recovery of capillary damage secondary to a systemic leak

CONCLUSIONS

Our understanding of capillary leak syndrome remains fragmented and weighted toward specific mediators contributing to the leak. The implications of extensive edema and the mechanism by which it resolves continue to be the subject of speculation rather than study.

Pancreas: healing response in critical illness

OBJECTIVE

The pathophysiology of acute pancreatitis represents a diverse mix of congenital, hereditary, and acquired problems associated with or causing acute pancreatic inflammation. Acute pancreatitis is characterized by acinar cell injury that may involve regional and systemic inflammatory responses. The systemic manifestations of acute pancreatitis are responsible for the majority of pancreatitis-associated morbidity and are due to the actions of specific inflammatory cytokines. This report summarizes this pancreatic injury, the role of cytokines in the pathogenesis of acute pancreatitis, and the pancreatic healing response that follows.

DESIGN

A comprehensive literature review of experimental pancreatitis as well as reports of cytokine involvement and healing response during clinical pancreatitis was performed.

RESULTS

Histamine release, bradykinin generation, and cytokine release play a significant role during acute pancreatic inflammation. Following an experimental insult, there is rapid expression of tumor necrosis factor-alpha, interleukin-6, interleukin-1, and chemokines by pancreatic acinar cells and/or transmigrated leukocytes. Preventing the action of these mediators has a profound beneficial effect in experimental animals. Pancreatic fibrosis is a central histologic response after pancreatitis. Transient collagen deposition with acinar necrosis occurs in acute pancreatitis; in chronic pancreatitis, permanent and disorganized pancreatic fibrosis and parenchymal cell atrophy occur.

CONCLUSIONS

Inflammatory mediators are responsible for the systemic manifestations of acute pancreatitis and the associated distant organ dysfunction. After the acute injury, regeneration or pancreatic repair is characterized by decreased release of proinflammatory mediators and decreased infiltrating inflammatory cells. Differentiation and proliferation of pancreatic myofibroblasts or "stellate" cells may be responsible for increased extracellular matrix production. The predictable nature in which the inflammation and fibrosis are produced may stimulate novel approaches to disease treatment.

Deactivation of ROCK-II by Y-27632 enhances basolateral pancreatic enzyme secretion and acute pancreatitis induced by CCK analogues

In isolated rat pancreatic acini, protein expression of RhoA and Rho-associated kinase, ROCK-II, and the formation of immunocomplex of RhoA with ROCK-II were enhanced by CCK-8, carbachol, and the phorbol ester TPA. The ROCK-specific inhibitor, Y-27632, did not alter basal amylase secretion, whereas it potentiated CCK-stimulated pancreatic enzyme secretion in vitro. During caerulein-induced pancreatitis occurring in mice in vivo, Y-27632 enhanced serum amylase levels and the formation of interstitial edema and vacuolization at 12-18h after the first injection of caerulein. Y-27632 in turn inhibited the recovery of protein expression of ROCK-II at 18h after the first caerulein injection. These results suggest that RhoA and ROCK-II assemble normal CCK-stimulated pancreatic enzyme secretion and prevent caerulein-induced acute pancreatitis.

TGF-beta 1 attenuates myocardial ischemia-reperfusion injury via inhibition of upregulation of MMP-1

Ischemia-reperfusion (I/R) is thought to upregulate the expression and activity of matrix metalloproteinases (MMPs), which regulate myocardial and vascular remodeling. Previous studies have shown that transforming growth factor-beta(1) (TGF-beta(1)) can attenuate myocardial injury induced by I/R. TGF-beta(1) is also reported to suppress the release of MMPs. To study the modulation of MMP-1 by TGF-beta(1) in I/R myocardium, Sprague-Dawley rats were given saline and subjected to 1 h of myocardial ischemia [total left coronary artery (LCA) ligation] followed by 1 h of reperfusion (n = 9). Parallel groups of rats were pretreated with recombinant TGF-beta(1) (rTGF-beta(1), 1 mg/rat, n = 9) before reperfusion or exposure to sham I/R (control group). I/R caused myocardial necrosis and dysfunction, indicated by decreased first derivative of left ventricular pressure, mean arterial blood pressure, and heart rate (all P < 0.01 vs. sham-operated control group). Simultaneously, I/R upregulated MMP-1 (P < 0.01). Treatment of rats with rTGF-beta(1) reduced the extent of myocardial necrosis and dysfunction despite I/R (all P < 0.01). rTGF-beta(1) treatment also inhibited the upregulation of MMP-1 in the I/R myocardium (P < 0.05). To determine the direct effect of MMP-1 on the myocardium, isolated adult rat myocytes were treated with active MMP-1, which caused injury and death of cultured myocytes, measured as lactate dehydrogenase release and trypan blue staining, in a dose- and time-dependent manner (P < 0.05). Pretreatment with PD-166793, a specific MMP inhibitor, attenuated myocardial injury and death induced by active MMP-1. The present study for the first time shows that MMP-1 can directly cause myocyte injury or death and that attenuation of myocardial I/R injury by TGF-beta(1) may, at least partly, be mediated by the inhibition of upregulation of MMP-1.

Transient and ectopic expression of lumican by acinar cells in L-arginine-induced acute pancreatitis

Lumican is a member of a small leucine-rich proteoglycan family. We previously found that lumican mRNA and its protein were ectopically and highly expressed in acinar cells in chronic pancreatitis (CP)-like lesions close to pancreatic cancer cells. CP-like lesions are characterized by acinar and ductal-ductular cell proliferation with expanding fibrosis. This finding suggests that lumican is ectopically synthesized by acinar cells under chronic inflammatory conditions and plays a role in fibrosis of the pancreas. However, the expression and role of lumican in acute inflammatory changes of the pancreas are not completely elucidated. In the present study, we aim to clarify whether lumican mRNA and its protein are expressed in exocrine or endocrine components in acute pancreatitis (AP). For experimental AP, Wistar rats received an intraperitoneal injection of L-arginine. Western blot analysis showed an intense 50-kDa band corresponding to the lumican protein in normal and L-arginine-treated rat pancreas. After L-arginine injection, three intense bands at 42, 57, and 92 kDa were detected on day 1. Immunohistochemically, the lumican protein was localized in ductal and a few centroacinar cells in the normal pancreas. After L-arginine injection, an immature fibrosis with fragmented and loose collagen fibers was observed in AP on day 4 and lumican immunoreactivity was detected in the collagen fibers. Lumican mRNA was faintly detected in islet cells in the normal pancreas, but it was strongly expressed in acinar and islet cells on day 1. Furthermore, lumican mRNA was expressed in many proliferating fibroblasts on day 4 by in situ hybridization. These findings indicate that lumican is transiently synthesized by acinar cells and fibroblasts in AP. Lumican proteins synthesized by acinar cells, islet cells, and fibroblasts may contribute to immature and transient fibrosis of AP.

Differential distribution of fibroblast growth factor (FGF)-7 and FGF-10 in L-arginine-induced acute pancreatitis

The regenerative process of the pancreas after acute pancreatitis (AP) is characterized by acinar and ductal cell proliferation with synthesis and transient deposition of extracellular matrices. Various growth factors were reported to be highly expressed in AP, but their regulation has not yet been clarified. Fibroblast growth factor (FGF)-7, also known as keratinocyte growth factor (KGF), and FGF-10 are members of the FGF family and show high structural homology and similar biological characteristics. Both are mainly synthesized by mesenchymal cells and stimulate epithelial cells via KGF receptor (KGFR) which is a splice variant of FGFR-2. In the present study, we attempted to immunohistochemically determine the localization of FGF-7 and FGF-10 in pancreatic tissues of an L-arginine-induced rat pancreatitis model. Furthermore, highly specific KGFR antibodies were prepared and used for Western blot analysis and immunohistochemistry. In the normal pancreas, FGF-7 was localized in alpha cells of islets, but FGF-10 was not detected. KGFR was also localized in islet cells, ductal cells, and centroacinar cells in the normal pancreas. In the pancreatic tissues of rats with L-arginine-induced pancreatitis, FGF-7 was localized in alpha cells, whereas FGF-10 was expressed in vascular smooth muscle cells (VSMCs). KGFR was not expressed in centroacinar cells and its level decreased after L-arginine treatment. However, KGFR was detected instead in some acinar cells and VSMCs in addition to islet cells. These findings suggest that FGF-7 and FGF-10 contribute to the regeneration and differentiation of acinar cells and angiogenesis in AP through KGFR.

Acute pancreatitis

Acute pancreatitis begins as acute pancreatic injury and may generate a systemic inflammatory response that evolves into multiorgan failure, leading to death. Multiple inciting factors such as toxins (alcohol), gallstones, or endoscopic retrograde cholangiopancreatography result in a cascade of events beginning with the intra-acinar activation of zymogens and the release of cytokines and other proinflammatory mediators. Their release is a major determinant of the systemic inflammatory response and distant organ failure. Attempts to attenuate the severity of acute pancreatitis by blocking specific inflammatory mediators have had limited success. This review is divided into experimental acute pancreatitis and clinical acute pancreatitis. The distinction is maintained because although animal models of disease have helped define the pathogenesis of acute pancreatitis, they do not completely reproduce the clinical syndrome of human acute pancreatitis or guarantee equal success of therapies in humans.