Endogenous endotoxin participates in causing a panenteric inflammatory ileus after colonic surgery.

OBJECTIVE: To investigate muscularis inflammation and endogenous endotoxin as causes of postoperative ileus. BACKGROUND: Postoperative inflammatory ileus of the colon is associated with a significant delay in gastrointestinal transit. We investigated whether these changes are caused by the downstream obstructive barrier of the surgically altered colon or by small intestinal muscularis inflammation itself. Furthermore, we evaluated the mechanistic role of gut derived endotoxin in the development of postoperative intestinal dysfunction. METHODS: Rats underwent surgical manipulation of the colon. Isolated gastrointestinal transit was analyzed in animals with ileostomy. The perioperative emigration of intracolonic particles was investigated by colonic luminal injection of fluorescently labeled LPS and microspheres. Mediator mRNA induction was quantified by real-time RT-PCR. Muscularis leukocytic infiltrates were characterized. In vitro circular muscle contractility was assessed in a standard organ bath. RESULTS: Ileostomy rats presented with a significant delay in small intestinal transit after colonic manipulation. This was associated with leukocyte recruitment and inflammatory mediator mRNA induction within the small intestinal muscularis. Colonic manipulation caused the transference of intracolonic LPS and microspheres into the intestinal muscularis. Postoperative in vitro small intestinal circular muscle contractility was impaired by 42% compared with controls. Gut decontamination and TLR-4 deletion significantly alleviated the small intestinal muscularis inflammation and prevented intestinal muscle dysfunction. CONCLUSIONS: Selective colonic manipulation initiates a distant inflammatory response in the small intestinal muscularis that contributes to postoperative ileus. The data provide evidence that gut-derived bacterial products are mechanistically involved in the initiation of this remote inflammatory cascade.

Altered inflammatory gene expression underlies increased susceptibility to murine postoperative ileus with advancing age.

Susceptibility to postoperative ileus following abdominal surgery increases with advancing age. The mechanisms underlying this phenomenon are unknown. This study compares functional and molecular endpoints between young-adult (2 mo old), middle-aged (15 mo old), and elderly mice (26-30 mo old) to identify potential mechanisms. Susceptibility to ileus was assessed by measuring gastrointestinal transit (geometric center) 24 h after anesthesia, laparotomy, and light manipulation (LM) of the small bowel. Proinflammatory (IL-6, COX-2, inducible nitric oxide synthase) and anti-inflammatory (IL-10, heme oxygenase-1) gene and protein expressions were determined by real time RT-PCR, Western blot, and ELISA. LM did not alter gastrointestinal transit in young animals (geometric center = 8.8 +/- 0.9), but transit was increasingly delayed in middle-aged (6.9 +/- 0.8, P = 0.03) and elderly animals (4.7 +/- 0.6, P = 0.013). Despite the lack of LM effect on transit in young mice, IL-6 and COX-2 mRNA expressions were significantly increased postoperatively (165 +/- 24-fold and 2.9 +/- 0.3-fold, respectively). Expressions were increased further in middle-aged mice (1,103 +/- 187-fold; 4.4 +/- 0.7-fold) and further still in elderly mice (1,218 +/- 168-fold; 6.9 +/- 0.3-fold). IL-10 and heme oxygenase-1 gene expressions were also elevated postoperatively in young mice (4.8 +/- 0.5-fold and 13.0 +/- 1.3-fold, respectively) and were further increased in middle-aged mice (7.5 +/- 0.6-fold; 21.8 +/- 3.2-fold). However, inductions in elderly mice were significantly blunted (5.8 +/- 0.9-fold; 16.9 +/- 0.8-fold). There is both an age-dependent increase in the proinflammatory mediator expression and an age-dependent decrease in anti-inflammatory mediator expressions following minor insult to the bowel. Such imbalances between pro- and anti-inflammatory mechanisms may form the basis for increased susceptibility to ileus and for the increased severity and duration of ileus observed in the elderly.

Genetic analysis of the glutathione s-transferase genes MGST1, GSTM3, GSTT1, and GSTM1 in patients with hereditary pancreatitis.

BACKGROUND: Specific mutations in the cationic trypsinogen gene ( PRSS1) are disease-causing in patients with hereditary pancreatitis, but the genetic background still remains mysterious in about 40% of patients with the disease. It has been suggested that oxidative stress contributes to pancreatic damage. The glutathione s-transferases (GSTs) represent major detoxification enzymes that protect cells from oxidative stress. METHODS: In the present study we tested whether mutations in the MGST1 and GSTM3 genes or common deletions in the GSTT1 and GSTM1 genes are associated with hereditary pancreatitis. We analyzed the entire coding region of MGST1 and GSTM3 in 30 patients that were tested negative for PRSS1 mutations, and we studied 55 controls. For GSTT1 and GSTM1, we investigated 75 hereditary pancreatitis patients who had been tested negative for PRSS1 mutations, 135 hereditary pancreatitis patients with a PRSS1 mutation, and 183 controls. Patients were further subclassified with regard to age of onset of disease as a marker of severity. RESULTS: No mutation was found in the MGST1 gene. In the GSTM3 gene, we detected a homozygous 670G > A polymorphism (V224I) with similar frequencies in patients and controls. We found no difference in the frequencies of the GSTT1 and GSTM1 null genotypes between patients and controls, and we detected no differences in age of onset in patients with or without GSTT1 and GSTM1 deletions. CONCLUSIONS: We conclude that genetic alterations in the MGST1, GSTM3, GSTT1, and GSTM1 genes do not play a dominant role in hereditary pancreatitis.

Inhibition of tumor necrosis factor receptor-1-mediated pathways has beneficial effects in a murine model of postischemic remodeling.

The aim of the present study was to investigate the importance of tumor necrosis factor (TNF)-alpha receptor-1 (TNFR1)-mediated pathways in a murine model of myocardial infarction and remodeling. One hundred and ninety-four wild-type (WT) and TNFR1 gene-deleted (TNFR1KO) mice underwent left coronary artery ligation to induce myocardial infarction. On days 1, 3, 7, and 42, mice underwent transesophageal echocardiography. Hearts were weighed, and the left ventricle (LV) was assayed for matrix metalloproteinase (MMP)-2 and -9 activity and for tissue inhibitor of MMP (TIMP)-1 and -2 expression. Deletion of the TNFR1 gene substantially improved survival because no deaths were observed in TNFR1KO mice versus 56.4% and 18.2% in WT males and females, respectively (P < 0.002). At 42 days, LV remodeling, assessed by LV function (fractional area change of 31.9 +/- 7.9%, 32.2 +/- 7.7%, and 21.6 +/- 7.1% in TNFR1KO males, TNFR1KO females, and WT females, respectively, P < 0.04), and hypertrophy (heart weight-to-body weight ratios of 5.435 +/- 0.986, 5.485 +/- 0.677, and 6.726 +/- 0.704 mg/g, P < 0.04) were ameliorated in TNFR1KO mice. MMP-9 activity was highest at 3 days postinfarction and was highest in WT males (1.9 +/- 0.4 4, 3.6 +/- 0.24, 1.15 +/- 0.28, and 1.3 +/- 1.2 ng/100 microg protein, respectively, in TNFR1KO males, WT males, TNFR1KO females, and WT females, respectively, P < 0.002), whereas at 3 days TIMP-1 mRNA fold upregulation compared with type- and sex-matched controls was lowest in WT males (138.32 +/- 13.05, 46.74 +/- 5.43, 186.09 +/- 28.07, and 101.76 +/- 22.48, respectively, P < 0.002). MMP-2 and TIMP-2 increased similarly in all infarcted groups. These findings suggest that the benefits of TNFR1 ablation might be attributable at least in part to the attenuation of cytokine-mediated imbalances in MMP-TIMP activity.

Mechanisms of polymicrobial sepsis-induced ileus.

Sepsis frequently occurs after hemorrhage, trauma, burn, or abdominal surgery and is a leading cause of morbidity and mortality in severely ill patients. We performed experiments to delineate intestinal molecular and functional motility consequences of polymicrobial sepsis in the clinically relevant cecal ligation and puncture (CLP) sepsis model. CLP was performed on male Sprague-Dawley rats. Gastrointestinal transit, colonic in vivo pressure recordings, and in vitro muscle contractions were recorded. Histochemistry was performed for macrophages, monocytes, and neutrophils. Inflammatory gene expressions were quantified by real-time RT-PCR. CLP delayed gastrointestinal transit, decreased colonic pressures, and suppressed in vivo circular muscle contractility of the jejunum and colon over a 4-day period. A leukocytic infiltrate of monocytes and neutrophils developed over 24 h. Real-time RT-PCR demonstrated a significant temporal elevation in IL-6, IL-1beta, monocyte chemoattractant protein-1, and inducible nitric oxide synthase, with higher expression levels of IL-6 and inducible nitric oxide synthase in colonic extracts compared with small intestine. Polymicrobial CLP sepsis induces a complex inflammatory response within the intestinal muscularis with the recruitment of leukocytes and elaboration of mediators that inhibit intestinal muscle function. Differences were elucidated between endotoxin and CLP models of sepsis, as well as a heterogeneous regional response of the gastrointestinal tract to CLP. Thus the intestine is not only a source of bacteremia but also an important target of bacterial products with major functional consequences to intestinal motility and the generation of cytokines, which participate in the development of multiple organ failure.