Protease activation during surgical stress in the rat small intestine

Osteopontin is an initial mediator of inflammation and liver injury during obstructive cholestasis after bile duct ligation in mice

Osteopontin (OPN) is a chemotactic factor which can be cleaved to the pro-inflammatory form by matrix metalloproteinases (MMPs). To test the hypothesis that OPN can modulate inflammatory liver injury during cholestasis, wild-type (WT) C57BL/6 and OPN knockout (OPN-KO) mice underwent bile duct ligation (BDL). OPN-KO mice showed significant reduction in liver injury (plasma ALT and necrosis) and neutrophil recruitment compared with WT animals at 24h but not 72h after BDL. In WT mice, a 4-fold increase in hepatic MMP-3 mRNA and elevated MMP activities and cleaved OPN levels were observed in bile. WT mice subjected to BDL in the presence of the MMP inhibitor BB-94 showed reduced liver injury, less neutrophil extravasation and diminished levels of cleaved OPN in bile. Thus, during obstructive cholestasis, OPN released from biliary epithelial cells could be cleaved by MMPs in bile. When the biliary system leaks, cleaved OPN enters the parenchyma and attracts neutrophils. In the absence of OPN, other chemoattractants, e.g. chemokines, mediate a delayed inflammatory response and injury. Taken together, our data suggest that OPN is the pro-inflammatory mediator that initiates the early neutrophil-mediated injury phase during obstructive cholestasis in mice.

Evaluation of dextrose water, black tea and orange juice on histopathologic recovery of surgery-induced intestinal damage in rabbits

BACKGROUND

The increase in intestinal permeability following damage to the intestinal mucosa in any surgical procedure, trauma or fasting is well- known.

OBJECTIVES

Our objective was to experimentally evaluate whether antioxidant consumption is associated with decreased intestinal damage in intestinal surgical procedures.

MATERIALS AND METHODS

Forty rabbits were used to compare the pathological changes in the intestine after consumption of dextrose water 5% (D5W), black tea and orange juice in fasting and in cases with intestine resection and anastomosis. They were divided in to five groups as shams (GI), NPO (G II), D5W (GIII), black tea (GIV) and orange juice groups (GV). In GII to GV group with median laparotomy, a 2 cm segment of jejunum was resected and ends of the bowel were anastomosed. Postoperatively, animals fasted for five days. Animals in GII were killed after five days of fasting. On day five case groups were given free access to drinking D5w (GIII), black tea solution (G IV) and orange juice (GV) for a further 7 days. On day 8, animals were reoperated and the repaired segment of intestine was removed. Morphologic data were compared in groups.

RESULTS

There were 8 rabbits in each group. There was a significant difference in villi lengths in the groups (P = 0.003). GV rabbits had obvious recovery of the villous architecture.

CONCLUSIONS

Orange juice as a source of vitamin C may be an appropriate liquid for postoperative recovery following intestinal surgery.

Effects of oxidative stress on mitochondrial content and integrity of human anastomotic colorectal dehiscence: a preliminary DNA study

BACKGROUND

Anastomotic dehiscence is one of the most severe complications of colorectal surgery. Gaining insight into the molecular mechanisms responsible for the development of anastomotic dehiscence following colorectal surgery is important for the reduction of postoperative complications.

OBJECTIVE

Based on the close relationship between surgical stress and oxidative stress, the present study aimed to determine whether a correlation exists between increased levels of reactive oxygen species and colorectal anastomotic dehiscence.

METHODS

Patients who underwent surgical resection for colorectal cancer were divided into three groups: patients with anastomotic dehiscence (group 1); patients without dehiscence who underwent neoadjuvant radiochemotherapy (group 2); and patients without anastomotic dehiscence who did not undergo neoadjuvant radiochemotherapy (group 3). Quantitative polymerase chain reaction and real-time polymerase chain reaction assays were performed to measure nuclear DNA and mitochondrial DNA (mtDNA) content, and possible oxidative damage to nonmalignant colon and rectal tissues adjacent to the anastomoses.

RESULTS

mtDNA content was reduced in the colon tissue of patients in groups 1 and 2. Rectal mtDNA was found to be more damaged than colonic mtDNAs in all groups. The 4977 bp common deletion was observed in the mtDNA of tissues from both the colon and rectum of all patients.

DISCUSSION

Patients in groups 1 and 2 were more similar to one another than to group 3, probably due to higher levels of reactive oxygen species in the mitochondria; the greater damage found in the rectum suggests that dehiscence originates primarily from the rectal area.

CONCLUSIONS

The present study of mtDNA analyses of normal human colon and rectal tissues from patients with colorectal cancer is among the first of its kind.

Allopurinol Prevents Erythrocyte Deformability Impairing but Not the Hematological Alterations After Limb Ischemia–Reperfusion in Rats

The measurement of red blood cell deformability provides a possible method for detecting the effect of ischemia-reperfusion on erythrocytes. In our study the effect of 1-h ischemia-reperfusion with or without allopurinol pretreatment on hematological parameters and red blood cell deformability was investigated in a follow-up experiment of 26 male CD outbred rats that were subjected to unilateral hind-limb ischemia by microvascular clips on femoral vessels for 1 h (IR, n = 6), some rats received allopurinol pretreatment under the same conditions (50 mg/kg, AP + IR, n = 8), others were subjected to sham operation (n = 6), and the rest of animals served as control (n = 6). Measurement of erythrocyte deformability using a bulk filtrometer with special setting of cell suspension hematocrit (1%), and determination of hematological parameters were performed daily for one week. In the IR group, relative cell transit time increased significantly on postoperative days 1 and 2, which was not observed in the other groups. Settings for the measurement of erythrocyte deformability by reducing the blood sample volume gave the possibility of monitoring the resulting changes in rats. Mean corpuscular volume and hemoglobin, platelet count, and platelet volume were higher in the IR and AP + IR groups than in the other groups. In summary, short-term ischemia and reperfusion induced lower red blood cell deformability in the early postoperative period, which could be prevented by allopurinol pretreatment.

The potential role for xanthine oxidase inhibition in major intra-abdominal surgery

BACKGROUND

Xanthine oxidase (XO) is a cytosolic metalloflavoprotein that has been implicated in the pathogenesis of a wide spectrum of diseases, and is thought to be the most important source of oxygen-free radicals and cell damage during re-oxygenation of hypoxic tissues. Clinical studies have already shown that XO inhibition is safe and effective for the treatment of gout, tumour-lysis syndrome, and to reduce complications such as post-operative arrhythmias, myocardial infarction and mortality in cardiovascular surgery. Here, we review the evidence from two decades of animal studies that have investigated the effects of XO inhibition during intra-abdominal surgery.

MATERIALS AND METHODS

A search of the Ovid MEDLINE database from 1950 through January 2007 was carried out using the following search terms: xanthine oxidase, allopurinol, ischemia, reperfusion, intestine, bowel, and general surgery.

RESULTS

The inhibition of XO has been shown to reduce oxidative stress, neutrophil priming, damage to intestinal mucosa due to ischemia reperfusion injuries, intestinal anastomotic dehiscence, bacterial translocation, adhesion formation, distant organ injury and mortality.

CONCLUSIONS

Despite this evidence which very strongly suggests a likely clinically beneficial role for XO inhibition in the elective and acute operative setting, it is surprising that such an approach has not been investigated in general surgery. There is now sufficient evidence to justify dedicated studies to determine the clinical benefits, dosing and duration of XO inhibition before and after gastrointestinal surgery.

Oxidative stress contributes to methotrexate-induced small intestinal toxicity in rats

BACKGROUND

Gastrointestinal toxicity is one of the most serious side effects in the methotrexate (MTX) treatment. However, the mechanism of the toxicity has not been completely clarified, which may be the reason why symptomatic therapy is carried out. On the other hand, the oxidative stress is known to play an important role in various diseases and drug-induced side effects. In this study the focus was on the oxidative stress in order to clarify the mechanism of MTX-induced small intestinal damage, especially neutrophil infiltration.

METHODS

MTX (20 mg/kg body wt) was administered to rats intravenously. Mucosal homogenates were prepared from the small intestine and used for assay of biochemical parameters, by which induction of oxidative stress and neutrophil infiltration were evaluated. N-acetylcysteine (NAC; 80 mg/kg body wt), an antioxidant or sodium tungstate (tungsten; 0.7 g/kg body wt), an inhibitor of xanthine dehydrogenase (XD)/xanthine oxidase (XO) known as an important source of reactive oxygen species (ROS) was given to rats with MTX to investigate the contribution of ROS to neutrophil infiltration.

RESULTS

The MTX treatment of rats induced the oxidative stress in the small intestine. The ROS production was seen preceding an increase of myeloperoxidase activity, which suggested neutrophil infiltration. Both treatments of NAC and tungsten prevented the MTX-induced ROS production and neutrophil infiltration.

CONCLUSIONS

These results suggest that oxidative stress plays an important role in the MTX-induced small intestinal damage, especially neutrophil infiltration. Thus, the modulation of oxidative stress would be useful in reducing intestinal damage in MTX treatment.

Role of intestine in postsurgical complications: involvement of free radicals

Surgery at any location in the body leads to surgical stress response and alterations in normal body homeostasis. The intestine is extremely sensitive to surgical stress even at remote locations and the gastrointestinal tract plays an important role in the development of postsurgical complications such as sepsis, the systemic immune response syndrome (SIRS), and multiple organ failure syndrome (MOFS). The generation of free radicals and subsequent biochemical alterations at the cellular and subcellular level in the intestine has been suggested to play an important role in this process. These oxidative stress-induced events in the mucosa might act as an initiator of distant organ damage and also facilitate bacterial adherence onto the epithelium and translocation into the systemic circulation. This review attempts to highlight the important role of intestine and oxygen free radicals in initiating post-surgical complications.

Detection of apoptotic cells in intestines from horses with and without gastrointestinal tract disease

OBJECTIVE

To identify apoptosis in equine intestines and determine whether apoptosis is associated with gastrointestinal tract disease or a specific tissue layer of intestine.

ANIMALS

38 horses that underwent surgery or were euthanatized for small or large intestine obstruction, strangulation, or distension and 9 control horses euthanatized for reasons other than gastrointestinal tract disease or systemic disease.

PROCEDURE

Specimens were collected at surgery from intestine involved in the primary lesion and distant to the primary lesion site or at necropsy from several sites including the primary lesion site. Histologic tissue sections were stained with H&E, and apoptosis was detected by use of the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique. The number of apoptotic cells per hpf was counted in the mucosa, circular muscle, longitudinal muscle, and serosa.

RESULTS

Apoptotic nuclei were seen in all layers of intestine. An increased number of apoptotic cells was found in the circular muscle of the intestine from horses with simple obstruction, compared with strangulating obstruction or healthy intestine. Intestine distant from a primary strangulating lesion had higher numbers of apoptotic cells than did intestine distant from a simple obstructive lesion or intestine taken at the site of a strangulating or simple obstructive lesion.

CONCLUSIONS AND CLINICAL RELEVANCE

Intestine from horses with obstructing or strangulating lesions in the small intestine and large colon had high numbers of apoptotic cells possibly because of ischemic cell injury and subsequent inflammation. Whether substantial apoptosis affects intestinal function is not yet known.

The Effects of Varying Oxygen Conditions and Immunoglobulin A on Barrier Defense to Bacterial Invasion

Tissue oxygenation is a critical factor in host defense against bacteria. Gut mucosal tissue oxygenation (partial pressure of O2) is normally low putting the gut at risk of invasion by luminal microbes. Secretory immunoglobulin (Ig) A (sIgA) is the principal immune defense at mucosal surfaces. The protective effect of IgA under low oxygen conditions is unknown. We studied the interaction of varying O2 environments and sIgA on protection against bacterial invasion in our in vitro model. Cell monolayers of Madin-Darby canine kidney (MDCK) cells transfected with the cDNA for polymeric immunoglobulin receptor were established in a two-chamber cell culture system. A commensal strain of Escherichia coli (108 colony-forming units) was added to the apical medium and cell cultures were placed in either a 5, 21, or 95 per cent O2 environment at 37° C. Polyclonal sIgA (100 μg/mL) was added to the apical chamber in subsets. Basal medium was sampled at intervals and bacterial translocation quantitated. The cell monolayers of MDCK transfected cells then had 100 μg/mL IgA added to the basal compartment at 4° C for 2 hours followed by various oxygen environments for 90 minutes. Afterwards apical medium was removed at one, 3, and 12 (overnight) hours. The bacterial translocation data showed a significance increase in translocation with hypoxia. Both increased oxygen and IgA abrogated these effects significantly. The transcytosis of IgA was increased during hypoxic conditions. Normal and hyperoxic conditions did not produce any significant difference in IgA transcytosis. We conclude that O2 and sIgA are protective against bacterial invasion at epithelial surfaces. Effects to either boost O2 delivery to the gut or enhance mucosal IgA production and delivery may be protective in the critically ill surgical patient.

Nitric oxide protects the intestine from the damage induced by laparotomy and gut manipulation

BACKGROUND

The intestine is highly susceptible to free radical-induced damage, and our earlier work has shown that surgical stress induces the generation of oxygen free radicals in enterocytes, resulting in intestinal damage along with ultrastructural changes. Since nitric oxide (NO) is an important mediator of gastrointestinal function, this study looked at the effect of NO on surgical stress-induced intestinal alterations.

MATERIALS AND METHODS

Control rats and rats pretreated with the NO donor l-arginine were subjected to surgical stress by opening the abdominal wall and handling the intestine as done during laparotomy. Enterocytes were isolated and homogenate prepared, and the protection offered by l-arginine against damage due to surgical stress was determined and compared with normal controls. Protection to structural as well as functional aspects of the intestine was also examined.

RESULTS

Intestinal manipulation affected intestinal structure as assessed by electron microscopy. Functional impairment of the enterocyte was also evident, with increased xanthine oxidase activity resulting in production of superoxide anion. This impairment is more dramatic in the crypt cells. Increased protease activity was also seen following laparotomy and handling. Pretreatment with the NO synthase substrate l-arginine prevented these damaging effects. Arginine protection was abolished in the presence of the NO synthase inhibitor NG-nitro-l-arginine methyl ester, indicating the role of NO.

CONCLUSION

Stress in the small intestine due to any surgery can affect enterocyte structure and function. These damaging effects can be prevented by NO, an important modulator of cellular function.