Fibronectin on the surface of biliary drain materials--a role in bacterial adherence

Management of Patients With Acute Cholecystitis After Percutaneous Cholecystostomy: From the Acute Stage to Definitive Surgical Treatment

Percutaneous cholecystostomy (PC) has become an important procedure for the treatment of acute cholecystitis (AC). PC is currently applied for patients who cannot undergo immediate laparoscopic cholecystectomy. However, the management following PC has not been well-reviewed. The efficacy of PC tubes has already been indicated, and compared to complications of other invasive biliary procedures, complications related to PC are rare. Following the resolution of AC, patients who can tolerate anesthesia and the surgical risk should undergo interval cholecystectomy to reduce the recurrence of biliary events. For patients unfit for surgery, whether owing to comorbidities, anesthesia risks, or surgical risks, expectant management may be applied; however, a high incidence of recurrence has been noted. In addition, several interesting issues, such as the indications for cholangiography via the PC tube, removal or maintenance of the PC catheter before definitive treatment, and timing of elective surgery, are all discussed in this review, and a relevant decision-making flowchart is proposed. PC is an effective and safe intervention, whether as expectant treatment or bridge therapy to definitive surgery. High-level evidence of post-PC care is still necessary to modify current practices.

[Mechanisms and prevention of biliary stent occlusion]

One of significant achievements of modern endoscopy is development of retrograde biliary stenting for obstructive jaundice. This method ensured widespread application of endoscopic decompression in the treatment of patients with malignant biliary obstruction as preparation before radical surgery and final palliative care. Endoscopic retrograde transpapillary stenting firmly took its place together with antegrade and percutaneous stenting. There are certain advantages of this technique including minimally invasiveness and favorable quality of life. However, this approach is associated with some drawbacks associated with stent occlusion and difficult correction of this complication. The maximum diameter of the plastic stent (PS) is determined by the width of the working channel of the duodenoscope. In this regard, self-expandable metal stents (SEMS) were developed to increase the diameter of bile drainage channel. SEMS are associated with prolonged function. However, there is another problem. It is a germination of SEMS followed by impossible removal of the stent for its subsequent replacement. A further step in development of endoscopic biliary stents was the use of special SEMS coating to exclude tumor or granulation ingrowth. The problem of biliary stent occlusion remains relevant despite some improvement of stenting results. Mechanisms of occlusion of biliary stents and prevention of these events are discussed in this review.

Impact of infected stent removal on recurrent cholangitis with time-to-event analysis

BACKGROUND

The optimal approach at treating infected biliary stents at the time of cholangitis remains unknown. This study aims to compare the efficacy of stent exchange versus stent sweeping/stent-in-stent approaches at treating cholangitis.

METHODS

The study was a retrospective cohort study. Patients with biliary stents and cholangitis were included. Outcomes were rate of recurrent cholangitis and time to recurrent cholangitis in those whose stents were left in place (stent sweeping and stent-in-stent) compared to those whose stents were removed (stent exchange). Primary analysis included patients with metal biliary stents only. Secondary analysis included those with metal and plastic biliary stents.

RESULTS

A total of 182 patients (age 64 ± 12;89 F) with a metal biliary stent(s) at index cholangitis were included. Of these, 40 (22%) had stents removed, i.e., stent exchange. The remaining 142 (78%) did not have stent removal (97 with stent-in-stent and 45 with stent sweeping). Recurrent cholangitis occurred in 22.5% and 42.3% in the stent removal and non-removal groups, respectively (p = 0.02). Stent removal remained a negative predictor of recurrent cholangitis after controlling for age, sex, history of diabetes, and chemotherapy (OR 0.39, p = 0.03). Median time from index cholangitis to recurrent cholangitis was shorter for patients whose stents were not removed compared to those whose stents were removed (182 vs 450 days, p = 0.011). On Cox regression model, stent removal remained a negative predictor of recurrent cholangitis after controlling for age, sex, history of diabetes, and chemotherapy (HR 0.41, p = 0.01). The findings persisted in the secondary analysis including both metal and plastic biliary stents (303 patients).

CONCLUSION

Biliary stent removal with stent exchange at the time of cholangitis appears to be more effective at preventing recurrent cholangitis than leaving an infected stent in the biliary system.

Mechanisms of Biliary Plastic Stent Occlusion and Efforts at Prevention

Biliary stenting via endoscopic retrograde cholangiopancreatography has greatly improved the quality of patient care over the last 30 years. Plastic stent occlusion limits the life span of such stents. Attempts to improve plastic stent patency duration have mostly failed. Metal stents (self-expandable metal stents [SEMSs]) have therefore replaced plastic stents, especially for malignant biliary strictures. SEMS are at least 10 times more expensive than plastic stents. In this focused review, we will discuss basic mechanisms of plastic stent occlusion, along with a systematic summary of previous efforts and related studies to improve stent patency and potential new techniques to overcome existing limitations.

Engagement of integrins as a cellular route of invasion by bacterial pathogens

Integrins are heterodimeric receptors that mediate important cell functions, including cell adhesion, migration and tissue organisation. These transmembrane receptors regulate the direct association of cells with each other and with extracellular matrix proteins. However, by binding their ligands, integrins provide a transmembrane link for the bidirectional transmission of mechanical forces and biochemical signals across the plasma membrane. Interestingly, several of this family of receptors are exploited by pathogens to establish contact with the host cells. Hence, microbes subvert normal eukaryotic cell processes to create a specialised niche which allows their survival. This review highlights the fundamental role of integrins in bacterial pathogenesis.

Plastic biliary stent occlusion: factors involved and possible preventive approaches

Endoscopic biliary stenting is today the most common palliative treatment for patients suffering from obstructive jaundice associated with malignant hepatobiliary tumors or benign strictures. However, recurrent jaundice, with or without cholangitis, is a major complication of a biliary endoprosthesis insertion. Thus, stent removal and replacement with a new one frequently occurs as a consequence of device blockage caused by microbial biofilm growth and biliary sludge accumulation in the lumen. Factors and mechanisms involved in plastic stent clogging arising from epidemiological, clinical and experimental data, as well as the possible strategies to prevent biliary stent failure, will be reviewed and discussed.

Effect of glass dissolution products on the detection of proteins by silver staining

The influence of glass dissolution on the silver staining of proteins was investigated by reacting glass microspheres of varying chemical durability in boiling Laemmli sample buffer (LSB) for up to 5 min. All three of the investigated glass compositions leached Na+ ions to varying degrees during boiling in LSB, thereby causing an increase in the pH of the sample buffer. The LSB supernatant from the dissolution tests was mixed with unreacted LSB containing human serum albumin (HSA) and standard one-dimensional SDS-PAGE was performed. Silver staining was then used to visualize protein bands within the gel. The 30 Na2O.70 SiO2 glass exhibited pronounced degradation as shown by scanning electron microscopy. Further experiments employing solutions of neat LSB and reacted LSB (i.e., LSB containing glass dissolution products) mixed at varying ratios demonstrated the apparent significance of sample pH in affecting the inhibition of silver staining. The cause of this behavior may be due to an interference with the fixation stage of the staining protocol, thereby resulting in the loss of protein in subsequent rinsing stages.

Confocal imaging of biofilm formation process using fluoroprobedEscherichia coli and fluoro-stained exopolysaccharide

We developed a novel method of evaluating biofilm architecture on a synthetic material using green fluorescent protein-expressing Escherichia coli and red fluorescence staining of exopolysaccharides. Confocal laser scanning microscopy observation revealed the time course of the change in the in situ three-dimensional structural features of biofilm on a polyurethane film without structural destruction: initially adhered cells are grown to form cellular aggregates and secrete exopolysaccharides. These cells were spottily distributed on the surface at an early incubation time but fused to form a vertically grown biofilm with incubation time. Fluorescence intensity, which is a measure of the number of cells, determined using a fluorometer and biofilm thickness determined from confocal laser scanning microscopy vertical images were found to be effective for quantification of time-dependent growth of biofilms. The curli (surface-located fibers specifically binding to fibronectin and laminin)-producing Escherichia coli strain, YMel, significantly proliferated on fibronectin-coated polyurethane, whereas the curli-deficient isogenic mutant, YMel-1, did not. The understanding of biofilm architecture in molecular and morphological events and new fluorescence microscopic techniques may help in the logical surface design of biomaterials with a high antibacterial potential.

Bile glycoprotein mucin in sludge occluding biliary stent

Endoscopic biliary stenting is a common treatment for the palliation of obstructive jaundice caused by inoperable malignant hepatobiliary tumors and benign strictures. The biliary stent, however, often becomes nonfunctional as a result of occlusion. In this study, we sought to confirm that bile glycoprotein mucin was a factor in stent occlusion and to investigate its possible role in biliary-stent blockage. The high-molecular-weight glycoprotein fraction was isolated from stent sludge with the use of gel filtration and a cesium chloride density gradient. This fraction was analyzed for amino-acid and carbohydrate compositions and was identified by means of immunoblotting with a specific monoclonal antibody against human gallbladder mucin. Furthermore, the distribution of bile glycoprotein mucin in stent sludge was immunologically demonstrated with fluorescent antibody, and the relationship between bile glycoprotein mucin and bacteria (demonstrated with DAPI stain) was observed. The high-molecular-weight glycoprotein extracts isolated from 11 patients' stent sludge showed strongly positive immunoreactivity with the monoclonal antibody against human gallbladder mucin. Immunofluorescence studies showed that very bright fluorescent signals of bile glycoprotein mucin often appeared on the surface of pigmented deposits, at the periphery of clumps of bacteria and along the inner wall of stents. In nonpigmented sludge, we noted fluorescent signals of bile glycoprotein mucin dispersed among clumps of bacteria. Bile glycoprotein mucin is a constituent of stent sludge. It may play a role in stent occlusion by affecting bacterial adherence to the stent surface or by promoting stent-sludge accumulation as one kind of cement among substances such as calcium bilirubinate and clumps of bacteria.

Role of bile mucin in bacterial adherence to biliary stents

Biliary stent placement is a well-established method of relieving obstructive jaundice. However, a frequent complication is occlusion of the stent caused by bacterial biofilm formation and sludge accumulation. In this study we investigated the possible effect of bile mucin on bacterial adherence to biliary stents at the initial stage of biofilm formation. By means of an in vitro bile-perfusion system, polyethylene stents were perfused with pig gallbladder bile infected with Escherichia coli. The concentrations of mucin in the pig bile were adjusted with purified mucin. The amount of bacteria adhering to the inner surface of the stents was measured and compared for stents perfused with bile containing various concentrations of mucin. Furthermore, we conditioned the stent inner surface with purified pig bile mucin and observed the effect of the conditioning on subsequent bacterial adherence. In addition, a common method for assaying bacterial adhesion with polystyrene microtiter plates was also used in this study. The results demonstrated that more bacteria adhered to the inner surface of stents perfused with bile containing 5 mg/mL mucin than of those perfused with bile containing 0.5 and 0 mg/mL mucin. Increased bacterial adherence was demonstrated on the stent surfaces conditioned with purified mucin compared with that seen on the nonconditioned stent surfaces. The optical densities indicating bacterial adhesion in the microtiter plate wells precoated with mucin were higher than those in non-coated plate wells. The in vitro results indicate that when a biliary stent is implanted in vivo, mucin in bile may condition the stent inner surface, modulate subsequent bacterial adherence to the surface, and participate in stent occlusion.

Exposure of plasma proteins on Dacron and ePTFE vascular graft material in a perfusion model

OBJECTIVES

to compare the exposure of plasma proteins adsorbed onto three vascular graft materials (polytetrafluoroethylene ePTFE and two modifications of polyethyleneterephthalate Dacron).

METHODS

surface exposure of fibronectin, vitronectin, thrombospondin, antithrombin III, IgG, high molecular-weight kininogen, fibrinogen, albumin and plasminogen was studied by incubation with radiolabelled antibodies in a perfusion model. Perfusion times with human plasma were 1, 4, 24 and 48 hours.

RESULTS

all proteins could be detected at 1, 4, 24 and 48 hours after the start of perfusion. Overall, the least amount of proteins adsorbed onto ePTFE.

CONCLUSIONS

the low adsorption of proteins onto ePTFE may be one of the reasons for the lower incidence of infections reported with this material.

Role of fibronectin-binding MSCRAMMs in bacterial adherence and entry into mammalian cells

Most bacterial infections are initiated by the adherence of microorganisms to host tissues. This process involves the interaction of specific bacterial surface structures, called adhesins, with host components. In this review, we discuss a group of microbial adhesins known as Microbial Surface Components Recognizing Adhesive Matrix Molecules (MSCRAMMs) which recognize and bind FN. The interaction of bacteria with FN is believed to contribute significantly to the virulence of a number of microorganisms, including staphylococci and streptococci. Several FN-binding MSCRAMMs of staphylococci and streptococci exhibit a similar structural organization and mechanism of ligand recognition. The ligand-binding domain consists of tandem repeats of a approximately 45 amino acid long unit which bind to the 29-kDa N-terminal region of FN. The binding mechanism is unusual in that the repeat units are unstructured and appear to undergo a conformational change upon ligand binding. Apart from supporting bacterial adherence, FN is also involved in bacterial entry into non-phagocytic mammalian cells. A sandwich model has been proposed in which FN forms a molecular bridge between MSCRAMMs on the bacterial surface and integrins on the host cell. However, the precise mechanism of bacterial invasion and the roles of FN and integrins in this process have yet to be fully elucidated.

Presence of vitronectin and activated complement factor C9 on ventriculoperitoneal shunts and temporary ventricular drainage catheters

OBJECT

The pathogenesis of cerebrospinal fluid (CSF) shunt infection is characterized by staphylococcal adhesion to the polymeric surface of the shunt catheter. Proteins from the CSF--fibronectin, vitronectin, and fibrinogen--are adsorbed to the surface of the catheter immediately after insertion. These proteins can interfere with the biological systems of the host and mediate staphylococcal adhesion to the surface of the catheter. In the present study, the presence of fibronectin, vitronectin, and fibrinogen on CSF shunts and temporary ventricular drainage catheters is shown. The presence of fragments of fibrinogen is also examined.

METHODS

The authors used the following methods: binding radiolabeled antibodies to the catheter surface, immunoblotting of catheter eluates, and scanning force microscopy of immunogold bound to the catheter surface. The immunoblot showed that vitronectin was adsorbed in its native form and that fibronectin was degraded into small fragments. Furthermore, the study demonstrated that the level of vitronectin in CSF increased in patients with an impaired CSF-blood barrier. To study complement activation, an antibody that recognizes the neoepitope of activated complement factor C9 was used. The presence of activated complement factor C9 was shown on both temporary catheters and shunts.

CONCLUSIONS

Activation of complement close to the surface of an inserted catheter could contribute to the pathogenesis of CSF shunt infection.

Binding of immobilized fibronectin by biliary drain isolates

Occlusion of biliary stents, as the result of bacterial adhesion and colonization onto biliary stents, still remains a major problem. Biliary proteins, such as fibronectin (Fn) and vitronectin (Vn), have been presumed to be involved in the process of bacterial adhesion to biliary biomaterial. In the present study, Fn binding by 5 strains of E. coli isolated from biliary drains or from bile was studied. All strains did not bind detectable amounts of soluble Fn but bound to immobilized plasma Fn. Adhesion of four strains of E. coli to ovalbumin was reduced by periodate treatment of ovalbumin, but adhesion to Fn was unaffected. Adhesion was inhibited by mannose-containing saccharides, trypsin treatment of the protein, and protease treatment of the bacterial cells. Autoradiography showed that components of cell extracts from three E. coli strains bind 125I-Fn but not a 150 kD Fn fragment. The findings indicate that the adhesion of these bacteria to Fn is a protein-protein interaction, inhibited by D-mannose, and possibly mediated by fimbrial components.

Fibronectin binding by Propionibacterium acnes

Strains of Propionibacterium acnes, isolated from different kinds of orthopaedic and biomaterial-associated infections and from skin flora were shown to express binding of soluble as well as immobilized fibronectin. Among these 7 strains isolated from orthopaedic infections, 2 from breast prostheses, and 9 skin isolates, 2, 2, and 5 strains respectively bound immobilized fibronectin. The fibronectin binding was sensitive to protease and heat treatment, and was inhibited by a cell surface extract from one of the binding strains. In SDS-PAGE and autoradiography of cell surface extracts, a band corresponding to a MW of about 80 kD reacted with fibronectin and the 150 kD fragment of fibronectin. Binding to fibronectin and the 150 kD fragment of fibronectin could be inhibited with heparin. We thus present a first Fn binding protein of P. acnes, a surface exposed protein of 80 kD. None of the strains bound soluble collagen, and only one strain expressed weak binding of vitronectin and bone sialoprotein II.

Protein depositions on one hydrocephalus shunt and on fifteen temporary ventricular catheters

Biomaterials are commonly used in modern medicine. Proteins are adsorbed to the surface of the biomaterial immediately after insertion. This report demonstrates the presence of adsorbed proteins in one infected cerebrospinal shunt from a child with hydrocephalus and on fifteen temporary ventricular catheters from adult patients with spontaneous or traumatic brain injuries. Depositions of vitronectin, fibrinogen and thrombospondin-fibronectin to some extent--on the shunt surface was imaged by field-emission scanning electron microscopy. Vitronectin, fibronectin, fibrinogen, and thrombospondin on the ventricular catheters were shown with radio-actively labelled antibodies. Furthermore, protein adsorption from human cerebrospinal fluid to heparinized and unheparinized polymers was studied under flowing conditions in vitro. On heparinized polymer, significantly reduced levels of vitronectin, fibronectin, and thrombospondin were exposed, as measured after 4 hours in vitro perfusion. After 24 hours perfusion, the differences in protein exposition between heparinized and unheparinized polymers were substantially reduced.

Biomaterial-associated staphylococcal peritoneal infections in a neutropaenic mouse model

Adhesion of staphylococcal cells to polyethylene with end point-attached heparin was quantified by bioluminescence. Staphylococcus epidermidis 3380 and the slime-producing S. epidermidis RP12 adhered to the highest extent, and S. lugdunensis 2342 to the least extent. Preincubation of the polymer with dialysis fluid reduced adhesion of S. epidermidis 3380 and RP12 but enhanced that of S. aureus, and preadsorption of the surface with fibronectin decreased subsequent adhesion of S. epidermidis and S. haemolyticus strains. When staphylococci were grown in the presence of a biomaterial their ability to activate peritoneal cells was decreased. The bactericidal activity was impaired, whereas ingestion of opsonized coagulase-negative staphylococci (CNS) strains was unaffected. With S. epidermidis RP12 the presence of biomaterial did not influence either phagocytosis or bactericidal effect of peritoneal cells. After intra-peritoneal challenge with staphylococcal strains, the organ uptake of S. aureus Cowan 1 was increased in normal mice whereas immunosuppressed mice died. CNS strains increased mainly in the peritoneal cavity of immunosuppressed mice. The uptake of bacteria in liver and kidneys was increased with S. epidermidis 3380, S. lugdunensis 2343 and S. schleiferi 667-88. Generally, CNS strains persisted in the peritoneal cavity of both normal and immunosuppressed mice. These data indicate that host defense mechanisms, mainly polymorphonuclear neutrophils, fail to eliminate CNS infections in the peritoneum, and that initial adhesion to an implanted biomaterial may be of lesser importance in the peritoneal cavity than in e.g. catheter-associated infections. There are strain-specific virulence factors of bacteria, and slime producing strains evade the host defense mechanisms more efficiently than non-slime producing strains.