Genomic and proteomic profiling II: comparative assessment of gene expression profiles in leiomyomas, keloids, and surgically-induced scars

BACKGROUND

Leiomyoma have often been compared to keloids because of their fibrotic characteristic and higher rate of occurrence among African Americans as compared to other ethnic groups. To evaluate such a correlation at molecular level this study comparatively analyzed leiomyomas with keloids, surgical scars and peritoneal adhesions to identify genes that are either commonly and/or individually distinguish these fibrotic disorders despite differences in the nature of their development and growth.

METHODS

Microarray gene expression profiling and realtime PCR.

RESULTS

The analysis identified 3 to 12% of the genes on the arrays as differentially expressed among these tissues based on P ranking at greater than or equal to 0.005 followed by 2-fold cutoff change selection. Of these genes about 400 genes were identified as differentially expressed in leiomyomas as compared to keloids/incisional scars, and 85 genes as compared to peritoneal adhesions (greater than or equal to 0.01). Functional analysis indicated that the majority of these genes serve as regulators of cell growth (cell cycle/apoptosis), tissue turnover, transcription factors and signal transduction. Of these genes the expression of E2F1, RUNX3, EGR3, TBPIP, ECM-2, ESM1, THBS1, GAS1, ADAM17, CST6, FBLN5, and COL18A was confirmed in these tissues using quantitative realtime PCR based on low-density arrays.

CONCLUSION

the results indicated that the molecular feature of leiomyomas is comparable but may be under different tissue-specific regulatory control to those of keloids and differ at the levels rather than tissue-specific expression of selected number of genes functionally regulating cell growth and apoptosis, inflammation, angiogenesis and tissue turnover.

Expression of receptor activator of nuclear factor-κb ligand in synovial tissue: Comparison with degradation of articular cartilage in temporomandibular joint disorders

OBJECTIVE

The present study was performed to investigate the correlations between expression of the receptor activator of nuclear factor-kappaB ligand (RANKL) in synovial tissue and the degrees of synovitis, degeneration of articular cartilage, and adhesions in patients with internal derangement (ID) of the temporomandibular joint (TMJ).

STUDY DESIGN

Expression of RANKL, detected immunohistochemically, and the severity of arthroscopic features (synovitis, degenerative changes of articular eminence, and adhesion) in 30 patients with ID of the TMJ were assessed and the correlations between them were analyzed statistically.

RESULTS

RANKL expression was detected in the cytoplasm of synovial lining cells, endothelial cells, and fibroblast cells. However, there were no correlations between RANKL expression in any cell type and the severity of arthroscopic features.

CONCLUSION

These observations indicated that the cellular source of osteoclastic differentiation exists in TMJ with ID and may provide insight into the mechanism of osteoclast differentiation.

[Can dexpanthenol prevent peritoneal adhesion formation? An experimental study]

BACKGROUND

Peritoneum has an intrinsic fibrinolytic activity that breaks the peritoneal adhesions. Ischemic peritoneal injuries interfere with this fibrinolytic activity. Local application of dexpanthenol, the alcohol form of pantothenic acid (vitamin B5) accelerates wound healing by increasing mitosis. We hypothesized that dexpanthenol would decrease peritoneal adhesions.

METHODS

In rats, antimesenteric border of cecum was abraded with gauze. No medication was given to the control group (n=15). Dexpanthenol was administered intraperitoneally (IP) (n=15, 25 mg/kg, before abdominal closure) or intravenously (IV) (n=15, 25 mg/kg, for 9 days after operation) in the experiment groups. On postoperative day 10, adhesions were graded; activities and concentrations of tissue plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), tPA/PAI-1 complex and hydroxyproline contents were determined in peritoneum.

RESULTS

Adhesion formation was decreased in IP dexpanthenol group compared with control group (p=0.034). tPA concentration and activity and tPA/PAI-1 complex levels were increased in the treated groups compared to controls. PAI-1 levels were similar among the three groups. Peritoneal hydroxyproline levels were lower in animals receiving IV dexpanthenol compared with control animals and in addition, they remained unchanged in IP dexpanthenol treated group (p=0.009, p=0.84, respectively).

CONCLUSION

Our results suggest that dexpanthenol administration through IP may reduce peritoneal adhesion formation probably by altering peritoneal fibrinolytic activity.

The effectiveness of a single intraperitoneal infusion of a neurokinin-1 receptor antagonist in reducing postoperative adhesion formation is time dependent

BACKGROUND

Current methods to prevent intraabdominal adhesions are not uniformly effective. We recently showed in rats that a neurokinin-1 receptor (NK-1R) antagonist is capable of reducing adhesion formation. To determine the clinical feasibility of using an NK-1R antagonist to reduce adhesions, this study examined the time dependence for the effectiveness of NK-1R antagonist administration and its effects on wound healing.

METHODS

Adhesions were surgically induced in rats receiving a single intraperitoneal infusion of the NK-1R antagonist, CJ-12,255, during or 1, 5, 12, or 24 hours after surgery. Adhesion formation was assessed 7 days later. In a subset of animals, tissue plasminogen activator (tPA) activity, which is a measure of peritoneal fibrinolytic activity, was determined in peritoneal fluid 24 hours after surgery (48 hours for animals infused at 24 hours). The tPA activity was also determined in nonoperated animals 24 hours after peritoneal injection of the NK-1R antagonist. Colonic burst pressures were measured 7 days after creation of anastomoses in rats that were administered the antagonist at surgery.

RESULTS

The NK-1R antagonist significantly reduced (P=.003) intraabdominal adhesions when administered during or 1 hour after surgery, only moderately reduced (P=.08) adhesions when administered at 5 hours, and had no effect at 12 or 24 hours. Peritoneal tPA activity was significantly increased (P<.05) in peritoneal fluid 24 hours after administration of the NK-1R antagonist regardless of the surgical procedure. The NK-1R antagonist did not alter colonic anastomotic healing.

CONCLUSIONS

These data show that some of the events critical to adhesion formation occur within the first 5 hours following an abdominal operation in this model. The fact that the NK-1R antagonist does not impair colonic anastomotic healing enhances its usefulness as a therapeutic agent to inhibit adhesion formation.

Modulation of the expression of peroxisome proliferators-activated receptors in human fibroblasts

To determine the levels of peroxisome proliferators-activated receptors (PPARs) in normal and adhesion fibroblasts, we utilized real-time reverse transcription-polymerase chain reaction to measure messenger RNA (mRNA) levels in fibroblasts from normal peritoneum and adhesions from five patients in both the presence or absence of dichloroacetic acid (DCA) and a cyclooxygenase-2 (COX-2) inhibitor, NS-398. Peroxisome proliferators-activated receptor alpha, PPARbeta, PPARgamma1, and PPARgamma2 mRNA are all present in normal peritoneal and adhesion fibroblasts, and selectively rose in response to hypoxia and either DCA or NS-398.

Human peritoneal adhesions show evidence of tissue remodeling and markers of angiogenesis

PURPOSE

This study was designed to investigate the vascular structure and angiogenic activity of human peritoneal adhesions.

METHODS

Adhesions were collected from patients undergoing laparotomy (n=32). Histologic features were documented and the distribution of mature and immature vascular markers were determined by immunolocalization and quantified by image analysis. The three-dimensional organization of blood vessels was investigated by confocal microscopy. Expression of vascular endothelial growth factor A, its receptor flk-1, and proliferating cell nuclear antigen were assessed by immunohistochemistry as indicators of angiogenic activity.

RESULTS

Adhesions were found to be vascularized structures comprising bundles of collagen, interspersed with varying amounts of adipose tissue. Functional blood vessels expressed recognized vascular markers (vWF, CD34, alpha-SMA, and CD105) and formed a branching network similar to that of the peritoneum. Those adhesions expressing vascular endothelial growth factor A and its receptor showed significantly higher numbers of immature vessels as defined by expression of CD105. Omental adhesions (n=16) contained significantly more adipose tissue (P<0.05) and displayed a higher microvessel density (P<0.01) but lower cellularity (P<0.05) compared with nonomental adhesions (n=16).

CONCLUSIONS

All adhesions contained functional blood vessels and most showed evidence of cell proliferation. The presence of vascular endothelial growth factor A and its receptor in human adhesions suggests ongoing angiogenic activity. This study demonstrates that adhesions are vascular structures with evidence of tissue remodeling and suggests potential for new prevention strategies involving antiangiogenic therapies.

The Role of Neutrophils and Oxygen Free Radicals in Post-Operative Adhesions

BACKGROUND

Postoperative intra-abdominal adhesion formation remains a major surgical problem. Surgery induces an inflammatory reaction, which is responsible for adhesion formation. Neutrophils and their oxygen-free radicals are key mediators in the early post-operative inflammatory response. The present study evaluates the effect of either blocking the influx of neutrophils or its products by scavenging oxygen-free radicals on adhesion formation.

MATERIALS AND METHODS

Reproducible rat models were used to induce post-surgical intra-abdominal adhesions. In the first experiment anti-neutrophil serum (ANS) was used to prevent neutrophils from entering the peritoneal cavity after surgery. In a second experiment superoxide dismutase (SOD), catalase, and mannitol were tested, to scavenge the superoxide, hydrogen peroxide, and hydroxyl radicals, respectively.

RESULTS

In positive control groups 69 to 76% of the area of interest contained adhesions. In all experimental groups, except for mannitol, a significant reduction in post-surgical adhesion formation could be achieved. ANS reduced adhesion formation by 38% (P < 0.001) and SOD/catalase by 42% (P < 0.01). Mannitol could not reduce adhesion formation.

CONCLUSIONS

Intra-abdominal influx of neutrophils after surgical peritoneal trauma plays an important role in post-operative adhesion formation. Preventing the intra-abdominal influx of neutrophils in the early post-operative inflammatory reaction can reduce adhesion formation, but an even more selective approach, by scavenging its products, proved as efficient.

Protective effect of aminoguanidine against oxidative stress in an experimental peritoneal adhesion model in rats

Postoperative intraperitoneal adhesion formation is a major cause of intestinal obstruction, pain and infertility. This experimental study was designed to evaluate the degree of adhesion formation and peritoneal tissue levels of malondialdehyde (MDA), reduced glutathione (GSH) and total nitrite and nitrate (NO) and the effect of aminoguanidine (AG) on these metabolite values after postoperative intraperitoneal adhesion formation in rats. A total of 21 adult male Wistar albino rats were randomly divided into three groups. Control rats were untreated; the AG group received AG 200 mg kg(-1) i.p. for 10 consecutive days intraperitoneally after surgery. The sham group was given 0.9% NaCl. The rats were killed on postoperative day 10. The peritoneal tissues were harvested to determine the tissue levels of MDA, GSH, and NO activity. For light microscopic evaluation, the cecum was removed. Adhesion formation scores in the AG group were significantly lower than those of the control and sham groups (p < 0.017, p < 0.026 respectively). In the AG-treated rats, tissue levels of MDA and NO were significantly lower than in the control group (p < 0.017). The levels of GSH in aminoguanidine-treated rats were significantly higher than those of the control group (p < 0.01). The severity of the inflammation was more prominent in the control group compared with the AG-injected rats. The results demonstrate that in this experimental model, intraperitoneal administration of aminoguanidine decreases the incidence and extent of peritoneal adhesions and causes a decrease in MDA and NO and an increase in GSH values.

Effect of oxidized regenerated cellulose (Interceed) on the expression of tissue plasminogen activator and plasminogen activator inhibitor-1 in human peritoneal fibroblasts and mesothelial cells

OBJECTIVE

To characterize the molecular changes that occur in normal fibroblasts, adhesion fibroblasts, and mesothelial cells as a result of exposure to oxidized regenerated cellulose (Interceed; Johnson & Johnson Medical, Inc., New Brunswick, NJ).

DESIGN

Control and Interceed-treated normal peritoneal fibroblasts, adhesion fibroblasts, and mesothelial cells in culture were assessed for messenger RNA levels of molecules known to be associated with adhesion development, using multiplex reverse transcriptase polymerase chain reaction (n = 4).

SETTING

University research laboratory.

PATIENT(S)

Normal and adhesion fibroblasts and mesothelial cells.

INTERVENTION(S)

Exposure of cells, normal fibroblasts, adhesion fibroblasts, and mesothelial cells to oxidized regenerated cellulose.

MAIN OUTCOME MEASURE(S)

Real-time reverse transcriptase polymerase chain reaction expression of messenger RNA tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), and tPA-PAI-1 ratio, an indicator of overall fibrinolytic activity.

RESULT(S)

Interceed treatment of normal peritoneal fibroblasts, adhesion fibroblasts, and mesothelial cells results in an increased expression of tPA in mesothelial cells and an increase in the tPA-PAI-1 ratio, signifying an overall increase in fibrinolytic activity.

CONCLUSION(S)

Interceed, which has been shown in multiple human in vivo studies to decrease postoperative adhesion development, increases the expression of tPA and the tPA-PAI-1 ratio (an indicator of overall fibrinolytic activity), thereby promoting dissolution of fibrin and healing without adhesion development. Thus, the ability of Interceed to reduce postoperative adhesion development may be derived from both a barrier and biologic effect.

Peritoneal fibrinolytic response to various aspects of laparoscopic surgery: a randomized trial

BACKGROUND

Peritoneal fibrinolysis is important in peritoneal wound healing processes and adhesion formation. The peritoneal fibrinolytic response to laparoscopy is merely unknown. In the present study we investigate the effect of short-term laparoscopy on the peritoneal fibrinolytic response and the influence of intra-abdominal pressure, light intensity and choice of dissection device on this response.

METHODS

There were 50 patients scheduled for laparoscopic cholecystectomy randomized in five groups operated with various pressures, light intensities, and dissection devices. Peritoneal biopsies were taken at the beginning and the end of the procedure. Tissue concentrations of tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor type 1 (PAI-1), and the tPA-activity were measured using ELISA techniques.

RESULTS

There were no differences in tPA antigen, tPA-activity, uPA antigen, or PAI-1 antigen concentrations in biopsies taken at the beginning compared to samples taken at the end of the operation. Different intra-abdominal pressures, light intensities and the choice dissection device did not affect any of the measured parameters.

CONCLUSION

Short-term laparoscopy does not affect the peritoneal fibrinolytic activity. The used intra-abdominal pressure, light intensity and choice of dissection device do not affect peritoneal activity during short-term laparoscopy.

Effects of hyperglycemia on the differential expression of insulin and insulin-like growth factor-I receptors in human normal peritoneal and adhesion fibroblasts

OBJECTIVE

To determine whether the insulin receptor (IR), insulin-like growth factor-I receptor (IGF-IR), and IGF-I are expressed differentially in fibroblasts isolated from normal peritoneal and adhesion tissue before and after 24-hour treatment with increasing glucose concentrations.

DESIGN

Prospective experimental study.

SETTING

University medical center.

PATIENT(S)

Primary cultures of fibroblasts established from peritoneal and adhesion tissues of the same patients.

INTERVENTION(S)

Glucose treatment of the primary cultured fibroblasts for 24 hours with increasing concentrations of glucose (100-850 mg/dL).

MAIN OUTCOME MEASURE(S)

Real-time polymerase chain reaction was used to measure messenger RNA (mRNA) levels for IR, IGF-IR, and IGF-I. Enzyme-linked immunosorbent assay was used to determine protein levels.

RESULT(S)

At the normal glycemic level (100 mg/dL), adhesion fibroblasts have significantly higher mRNA levels of the IR (7.96 +/- 0.15 vs. 6.97 +/- 0.16; P<.05), IGF-IR (7.72 +/- 0.22 vs. 6.88 +/- 0.06; P<.05), and IGF-I (7.04 +/- 0.10 vs. 5.92 +/- 0.10; P<.05) when compared with normal fibroblasts, respectively. Data are expressed as log(mRNA/microg RNA). Normal fibroblasts respond to increasing glucose concentrations by increasing the expression levels of the IR, IGF-IR, and IGF-I, whereas adhesion fibroblasts respond by decreasing the expression of the IR, IGF-IR, and IGF-I.

CONCLUSION(S)

The differential expression of the IR, IGF-IR, and IGF-I in adhesion fibroblasts may contribute to the pathogenesis of fibrosis observed in diabetic patients.

Adenoviral-mediated gene expression of hepatocyte growth factor prevents postoperative peritoneal adhesion in a rat model

BACKGROUND

Mesothelial cell proliferation and migration play important roles in reducing formation of postoperative peritoneal adhesions. Hepatocyte growth factor (HGF) is a multifunctional cytokine that stimulates proliferation and migration of various cell types, including mesothelial cells.

METHODS

We investigated the effect of adenovirus-mediated HGF gene expression on the proliferation and migration of mesothelial cells and evaluated its preventive effects on postoperative formation of peritoneal adhesions. Rat mesothelial cells were isolated and characterized by expression of cytokeratin and vimentin.

RESULTS

Immunohistochemical staining showed that these cells expressed c-Met, the receptor for HGF. Adenoviral-mediated HGF gene transfer into mesothelial cells resulted in high expression of HGF and enhanced migration. To evaluate the preventive effects of adenoviral-mediated HGF gene transfer on the formation of postoperative peritoneal adhesion, we employed a rat model of cecum abrasion-induced adhesion formation in which 80% of the rats developed postoperative peritoneal adhesions. Local application of recombinant adenovirus carrying the HGF gene reduced adhesion formation in 16 of 20 control rats compared with 7 of 20 treated rats in this model.

CONCLUSIONS

These results suggest that adenoviral-mediated HGF gene transfer may be a novel strategy for preventing postoperative peritoneal adhesions.

[Peritoneal mesothelium--the role in fibrin transformations]

Peritoneum is a serous membrane with a significant fibrinolytic potential, playing an important role in the abdominal response to trauma. Peritoneum takes part in the formation and degradation of postoperative adhesions. The sequence of changes during the adhesion formation is indispensable in the healing of peritoneal trauma. Presented paper describes the short historical update of mesothelial research and review of contemporary knowledge over the peritoneal function with special regard to its fibrinolytic activity. The factors influencing the fibrinolytic capacity of peritoneum were discussed, as well as present pathways of research on the prevention of postoperative adhesion formation.

Measurement of oxygen and nitric oxide levels in vitro and in vivo: relationship to postoperative adhesions

This article demonstrates the ability to measure the actual oxygen and nitric oxide levels in cultured fibroblasts established from normal peritoneum and adhesion tissues with and without hypoxia treatment and to measure levels of oxygen and nitric oxide in vivo in various tissues before and after abrasion.

Experimental manipulation of transforming growth factor-beta isoforms significantly affects adhesion formation in a murine surgical model

Transforming growth factor-beta (TGF-beta), a multifunctional growth factor, represents three mammalian isoforms, TGF-beta1, TGF-beta2, and TGF-beta3. In cutaneous wound healing, combined neutralization of TGF-beta1 and -beta2 or addition of TGF-beta3 reduces scar formation. Here, we investigated whether experimental manipulation of TGF-beta isoforms reduced adhesion formation after injury to the peritoneum. Adhesions were produced in mice by surgical abrasion of adjacent serosa followed by close apposition. In the first part of this study, a detailed analysis of TGF-beta isoform distribution was performed through immunolocalization. TGF-beta isoforms clearly showed a unique temporal and spatial pattern of expression after peritoneal wounding. Based on this pharmacokinetic data, we next administered neutralizing antibodies to TGF-beta1 and -beta2 or exogenous TGF-beta3 peptide by local application and intraperitoneal injection at various times before and after surgery. At day 7 after surgery, addition of neutralizing antibodies to both TGF-beta1 and -beta2 significantly reduced the number and size of adhesions (P < 0.05) compared with the vehicle control. By contrast, exogenous addition of TGF-beta3 either had no effect or increased adhesion formation compared to the vehicle control. In conclusion, these results show that by blocking both TGF-beta1 and TGF-beta2 using neutralizing antibodies, it is possible to prevent abdominal adhesion formation.

Chinese medicine compound Changtong oral liquid on postoperative intestinal adhesions

AIM: The aim of this study was to observe the effect of a Chinese medicine compound Changtong oral liquid (CT) on tissue plasminogen activity (t-PA), plasminogen activator inhibitor (PAI), TGF-β1 and hydroxyproline (OHP).

METHODS: Two sets of animal experiments were performed in the present study. Forty New Zealand rabbits and 48 Sprague-Dawley (SD) rats were assigned randomly to one of the five groups: sham adhesion, adhesion with saline, adhesion with low dosage of the CT, adhesion with middle dosage of the CT and adhesion with high dosage of the CT. t-PA and PAI activity in plasma, OHP and TGF-β1 expression in adhesion were investigated. Analysis of variance was used to test differences among groups.

RESULTS: CT treatment increased plasma t-PA activity in rabbits but decreased TGF-β1 activity in rats. The data were expressed from low to high dose respectively as follows: t-PA, 46.1±8.6 μkat/L, 59.6±10.1 μkat/L, 64.0±11.5 μkat/L; TGF-β1 28±7.23%, 31±3.05%, 30±4.04%. There were significant differences compared with saline-treated animals (t-PA 26.4±5.1 μkat/L, TGF-β1 54±5.51%). OHP content in cecum of rabbits from middle and high but not low dose of CT lowered significantly as compared with saline-treated rabbits, 0.3641±0.1373, 0.3348±0.0321, 0.2757±0.0497 mg/g vs 0.4183±0.0883 mg/g of protein, P>0.05, P<0.05, P<0.05 respectively. The rabbit plasma PAI activity and OHP content in abdominal wall had no difference in all groups.

CONCLUSION: CT treatment significantly enhanced t-PA activity in rabbits, but decreased TGF-β1 content in rats, OHP content in cecum of rabbits, and failed to affect the activity of PAI and OHP content in abdominal wall in rabbits, compared with saline group. The result suggests that CT could effectively prevent adhesions without interfering wound healing.

Hypoxia upregulates cyclooxygenase-2 and prostaglandin E levels in human peritoneal fibroblasts

OBJECTIVE

To determine the levels of COX-1, COX-2, and prostaglandin (PG) E(2) in human fibroblasts isolated from normal peritoneal and adhesion tissues.

DESIGN

Prospective experimental study.

SETTING

University medical center.

PATIENT(S)

Fibroblast cultures from both peritoneum and adhesion tissues of five patients.

INTERVENTION(S)

Treatment of the primary cultured fibroblasts with NS398.

MAIN OUTCOME MEASURE(S)

We used Western blot to determine the effects of hypoxia on COX-1 and COX-2 levels from lysates of normal peritoneal and adhesion fibroblasts before and after hypoxia. We also used the ELISA techniques to determine PGE(2) levels in media collected from these fibroblasts before and after hypoxia and with and without NS398, a COX-2-specific inhibitor.

RESULT(S)

There was no difference in COX-1 levels between normal and adhesion fibroblasts with and without hypoxia. Basal COX-2 and PGE(2) levels were significantly higher in adhesion than normal fibroblasts. Hypoxia gradually increased COX-2 and PGE(2) levels in normal peritoneal fibroblasts over time, reaching a peak at 24 hours but had no effect on adhesion fibroblasts. Inhibition of COX-2 by NS398 significantly reduced PGE(2) levels in both normal and adhesion fibroblasts.

CONCLUSION(S)

The presence of higher levels of COX-2 in adhesion fibroblasts and the induction of COX-2 in normal peritoneal fibroblasts in response to hypoxia indicate a possible inflammatory response. Regulation of COX-2 may alter peritoneal healing and may provide the opportunity to reduce postoperative adhesion development.

Tissue models of peritoneal fibrosis

OBJECTIVE

To evaluate the utility of peritoneal pathologic samples, unrelated to peritoneal dialysis (PD) treatment, for the study of peritoneal fibrosis and inflammation.

METHODS

Comparative morphologic and immunohistochemical study of peritoneal pathologic samples unrelated to PD with peritoneal biopsies from PD patients with special emphasis on the expression of myofibroblastic and epithelial-to-mesenchymal transition markers.

RESULTS

Regarding morphology, PD-related simple fibrosis was less cellular, with greater stromal hyalinization, determining a homogeneous, hypocellular aspect of the submesothelium. In contrast, non-PD fibrosis was more cellular with an extracellular matrix showing a dense and fibrillar quality with wide bundles of collagen. Hylinazing vasculopathy was only present in PD samples. Myofibroblastic differentiation and epithelial-to-mesenchymal transition were common findings in all situations of peritoneal fibrosis. Calponin and calretinin are useful cellular markers to study such fibrogenic mechanisms and correlate with other well-known markers such as a -SMA and cytokeratins. Their expression was much more intense in those samples showing acute inflammation (peritonitis).

CONCLUSIONS

Non-PD models of peritoneal fibrosis seem very useful to evaluate important features of human peritoneal pathology such us fibrogenesis, and inflammation. Fibrogenic events such as myofibroblastic differentiation and epithelial-to-mesenchymal transition are evident in these tissue samples allowing us to use them as an accessible source for in vivo and ex vivo studies. Both events show their maximal expression in situations of acute inflammation supporting the important role that peritonitis episodes play in the progression of fibrosis.

Expression pattern and regulation of genes differ between fibroblasts of adhesion and normal human peritoneum

BACKGROUND

Injury to the peritoneum during surgery is followed by a healing process that frequently results in the attachment of adjacent organs by a fibrous mass, referred commonly as adhesions. Because injuries to the peritoneum during surgery are inevitable, it is imperative that we understand the mechanisms of adhesion formation to prevent its occurrence. This requires thorough understanding of the molecular sequence that results in the attachment of injured peritoneum and the development of fibrous tissue. Recent data show that fibroblasts from the injured peritoneum may play a critical role in the formation of adhesion tissues. Therefore, identifying changes in gene expression pattern in the peritoneal fibroblasts during the process may provide clues to the mechanisms by which adhesion develop.

METHODS

In this study, we compared expression patterns of larger number of genes in the fibroblasts isolated from adhesion and normal human peritoneum using gene filters. Contributions of TGF-beta1 and hypoxia in the altered expression of specific genes were also examined using a semiquantitative RT-PCR technique.

RESULTS

Results show that several genes are differentially expressed between fibroblasts of normal and adhesion peritoneum and that the peritoneal fibroblast may acquire a different phenotype during adhesion formation. Genes that are differentially expressed between normal and adhesion fibroblasts encode molecules involved in cell adhesion, proliferation, differentiation, migration and factors regulating cytokines, transcription, translation and protein/vesicle trafficking.

CONCLUSIONS

Our data substantiate that adhesion formation is a multigenic phenomenon and not all changes in gene expression pattern between normal and adhesion fibroblasts are the function of TGF-beta1 and hypoxia that are known to influence adhesion formation. Analysis of the gene expression data in the perspective of known functions of genes connote to additional targets that may be manipulated to inhibit adhesion development.

Synthesis and evaluation of long-acting D-penicillamine derivatives

This study extends the use of two lathyrogens, ss-aminopropionitrile (BAPN) and D-penicillamine (DPA) from daily systemic or local-topical administration to long-time acting agents. This was achieved by converting the hydrophilic drugs into lipophilic derivatives. The synthesis of functional derivatives of DPA consisted in esterification with methyl-, hexyl-, or benzyl alcohols in the presence of thionylchloride. The esters formed were hydrochlorides, acidic and soluble in water. During neutralization in vitro or in vivo by tissue fluid, an oily substance is formed that elutes from a hydrogel polymer at a much slower rate than hydroplilic DPA itself. The degree of lipophilicity, measured as a partition coefficient between octanol/water, was highest for hexyl ester and lowest for methyl ester DPA. A single injection of either DPA hexyl ester HCl or 3-hexyl(amino) propionitrile into the full thickness skin incision wound in rats significantly lowered the breaking strength of the wound 12 days after injection, indicating the interference with collagen cross-linking. Both agents injected into the breast adenocarcinoma in Fisher rats significantly inhibited tumor growth without any signs of local or systemic toxicity. We conclude that these lipophilic lathyrogens with prolonged effectiveness are suitable in the treatment of pathologies, consisting of excessively cross-linked or deposited collagen (fibrotic adhesions, strictures, stenosis, and scar contractures) and in the treatment of single, solitary tumors, malignant and benign.

Differential expression of alpha smooth muscle cell actin in human fibroblasts isolated from intraperitoneal adhesions and normal peritoneal tissues

OBJECTIVE

To determine whether alpha smooth muscle cell actin (alphaSMCA) is expressed in human fibroblasts isolated from normal peritoneal and adhesion tissues.

DESIGN

Prospective, experimental study.

SETTING

University medical center.

PATIENT(S)

Five patients undergoing laparotomy for adhesiolysis for pelvic pain.

INTERVENTION(S)

Primary culture of fibroblasts from both peritoneum and adhesion tissues.

MAIN OUTCOME MEASURE(S)

Immunohistochemistry techniques were used to determine whether alphaSMCA was present in normal peritoneal and adhesion fibroblasts from the same patients. Cultured fibroblasts from all tissues were also fixed on slides and stained with alphaSMCA monoclonal antibody labeled with immunofluorescence.

RESULT(S)

Alpha SMCA protein was present in very low levels in the cytoplasm of normal peritoneal fibroblasts from all five subjects, as compared with high levels present in adhesion fibroblasts from the same patients.

CONCLUSION(S)

Adhesion fibroblasts develop a specific phenotype, an adhesion phenotype, which in part is characterized by the over-expression of alphaSMCA. The over-expression of alphaSMCA in adhesion fibroblasts indicates a possible response to peritoneal injury. Regulation of alphaSMCA might alter peritoneal healing and might provide the opportunity to reduce postoperative adhesion development.

Role of nitric oxide in apoptosis of human peritoneal and adhesion fibroblasts after hypoxia

OBJECTIVE

To study the modulation of the inducible nitric oxide synthase/nitric oxide (iNOS/NO) expression system in fibroblasts isolated from human peritoneum and adhesion tissues by hypoxia.

DESIGN

Prospective experimental study.

SETTING

University medical center.

PATIENT(S)

Cultures of fibroblasts from both peritoneum and adhesion tissues of five patients.

INTERVENTION(S)

Hypoxia treatment of the primary cultured fibroblasts.

MAIN OUTCOME MEASURE(S)

We used Western and Northern blots to determine whether iNOS mRNA and its protein were present in peritoneal and adhesion fibroblasts and whether this expression is modulated by hypoxia. Multiplex reverse transcription polymerase chain reaction (RT-PCR) technique was used to quantify type I collagen mRNA in response to NG-nitro-L-arginine methyl ester (L-NAME). A terminal deoxynucleotidyl transferase mediated dUTP nick-end-labeling (TUNEL) assay was used to quantify apoptosis in response to NO donor S-nitro-N-acetyl-penicillamine (SNAP) treatment. A Griess assay was used to measure NO levels.

RESULT(S)

Peritoneal fibroblasts have significantly higher NO levels than adhesion fibroblasts. Hypoxia decreased NO in peritoneal fibroblasts to levels observed for adhesion fibroblasts. In addition, hypoxia increased both mRNA and protein levels of the iNOS gene in peritoneal and adhesion fibroblasts. Augmentation of NO by SNAP treatment increased apoptosis in adhesion fibroblasts. In contrast, SNAP had no effect on apoptosis of peritoneal fibroblasts. Inhibition of NO by L-NAME treatment increased type I collagen mRNA levels in peritoneal fibroblasts.

CONCLUSION(S)

Our findings confirm that adhesion fibroblasts produce less NO than normal peritoneal fibroblasts; NO may be the mechanism responsible for the creation and persistence of the adhesion phenotype.

A neurokinin 1 receptor antagonist decreases postoperative peritoneal adhesion formation and increases peritoneal fibrinolytic activity

Fibrous adhesions remain a major sequela of abdominal surgery. The proinflammatory peptide substance P (SP), known to participate in inflammatory events, may play a key role in adhesion formation. This hypothesis was tested by using an antagonist, CJ-12,255 (Pfizer), that blocks the binding of SP to the neurokinin 1 receptor (NK-1R). Adhesion formation was surgically induced in the peritoneum of rats receiving daily doses of the NK-1R antagonist (NK-1RA; 5.0 or 10.0 mg/kg per day) or saline. On postoperative day 7, both the low and high doses of NK-1RA significantly (P < 0.05) reduced adhesion formation by 45% and 53%, respectively, compared with controls. Subsequently, the effect of NK-1RA administration on peritoneal fibrinolytic activity was investigated to determine a potential mechanism for SP action in the peritoneum. Samples were collected from nonoperated controls and from animals 24 h postsurgery that were administered either NK-1RA or saline. Fibrinolytic activity in peritoneal fluid was assayed by zymography, and expression of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1, both regulators of fibrinolytic activity, was assessed in peritoneal tissue and fluid by RT-PCR and bioassay, respectively. NK-1RA administration led to a marked (P < 0.05) increase in tPA mRNA levels in peritoneal tissue compared with nonoperated and saline-administered animals. Likewise, NK-1RA administration significantly (P < 0.05) increased tPA in the peritoneal fluid. These data suggest that activation of the NK-1R promotes peritoneal adhesion formation by limiting fibrinolytic activity in the postoperative peritoneum, thus enabling fibrinous adhesions to persist.

Non-steroidal anti-inflammatory drugs decrease the quality of pleurodesis after mechanical pleural abrasion

OBJECTIVE

Non-steroidal anti-inflammatory drugs (NSAIDs) are often applied for pain management after thoracic surgery. Since these drugs diminish collagen deposition through inhibition of the prostaglandin synthesis, we investigated their effects on adhesion formation after endoscopic mechanical pleural abrasion, which is often applied in the therapy of pneumothorax.

METHODS

Mechanical pleural abrasion was performed unilaterally by the use of video-assisted thoracoscopic surgery technique in an established pig model. Ten animals (41.3+/-3.4 kg) were divided into a treatment group and a control group. In the treatment group, animals received 100 mg diclofenac (2 mg/kg body weight) orally daily for 3 weeks after surgery. At 3 weeks, all animals were sacrificed and efficacy of pleurodesis was macroscopically assessed by three independent reviewers blinded to the treatment of animals using a five-point severity pleurodesis score (from 0, no adhesions to 4, complete symphisis) and obliteration grade rating the distribution of adhesions (from 0, no adhesions to 4, adhesions in the whole chest). Microscopic evaluation was performed by two pathologists blinded to the study groups as well. A four-point score assessed the amount of collagen deposition (from 1, a few collagen fibers to 4, scar).

RESULTS

Gross observation showed more dense adhesions in control animals with a median pleurodesis score of 3.67+/-1.0 in comparison to 2+/-2.2 in the treatment group (P = 0.01 *, Mann-Whitney non-parametric test). Distribution of adhesions was comparable in both groups with a median obliteration score of 3.67+/-1.3. Histopathologic examination showed a higher amount of collagen deposition in the control group, suggesting more dense adhesions, whereas in the treatment group there was loose granulation tissue (score of 4.0+/-0.8 vs. 2.3+/-1.0 in the treatment group, P = 0.06). The degree of inflammatory reaction was comparable in the two groups.

CONCLUSIONS

Our results demonstrate that perioperative use of NSAIDs highly affects the quality of pleural adhesions obtained after mechanical abrasion in this pig model, which further suggests that these drugs should be avoided for pain management when a pleurodesis is performed.

Midkine, a heparin-binding cytokine, plays key roles in intraperitoneal adhesions

Midkine is a heparin-binding cytokine or growth factor and promotes the migration of inflammatory leukocytes. Upon partial hepatectomy, adhesion of the intestine was less severe in midkine-deficient mice than in wild-type mice. In a newly developed assay, in which the omentum adhered to the injured peritoneal wall, the incidence of adhesion in the deficient mice was reduced to 20% of that in the wild-type mice. Administration of midkine to the deficient mice increased the frequency of adhesion. The area of adhesion was also reduced to 8.3% in the deficient mice. The extent of migration of macrophages and neutrophils in the omentum around the adhesive region was reduced in the deficient mice. Therefore, midkine was concluded to play important roles in the formation of intraperitoneal adhesions, at least partly by promoting the migration of macrophages and neutrophils to the omentum.