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Background: After massive bowel resection, bacterial overgrowth is frequent and favors the occurrence of Gram-negative intestinal bacterial translocation (BT). Probiotics have been recommended in several diseases and may also have beneficial effects on BT. Conversely, polymerase chain reaction (PCR) technique has shown better sensitivity than conventional methods in bacterial detection and has not been investigated in experimental models of short bowel syndrome and BT.Objective: To test the hypothesis that Bifidobacterium lactis (BL) administration decreases Escherichia coli bacterial translocation (ECBT) in experimental short bowel syndrome and to confirm the better sensitivity of PCR technique to detect ECBT.Methods: Forty-eight adult Wistar rats, orally fed with standard rat chow and tap water ad libitum, were maintained in individual metabolic cages for 10 days and divided into three groups: Control group (n = 15): non-manipulated animals. RES group (n = 15): 80% gut resection. 1 ml of sterile water was administered daily after orogastric intubation. RES-PRO group (n = 18): same resection as RES group and daily administration of 7.8 × 10(9) BL (CFU). At the end of the study, portal blood, peripheral blood and mesenteric lymph node (MLN) samples were recovered and cultured. Also, genomic DNA from E. coli was detected by PCR technique.Results: In conventional culture there was no ECBT in control animals whereas 73% of RES and 33% of RES-PRO animals showed it. PCR detected ECBT in 47, 87 and 33%, respectively, showing higher sensitivity. [ABSTRACT FROM AUTHOR]

Introduction: Transforming growth factor beta (TGF-β) has been shown to affect epithelial cell differentiation and proliferation through epithelial-mesenchymal and epithelial-immune cell interaction. In the present study, we evaluated the effect of TGF-β2-enriched polymeric diet (Modulen) on enterocyte turnover in a rat model of short bowel syndrome (SBS).Methods: Male rats were divided into four groups: Sham rats and Sham-TGF-β rats underwent bowel transection, and were treated with TGF-β from the 4th postoperative day, SBS rats underwent a 75% bowel resection, and SBS-TGF-β rats underwent bowel resection and were treated with TGF-β-enriched diet similar to Group B. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined on day 15. Real-time PCR was used to determine Bax and Bcl-2 mRNA expression.Results: Treatment of SBS animals with TGF-β2 supplemented diet led to a significant decrease (vs. SBS rats) in bowel weight in ileum (18%, P < 0.05), mucosal DNA content in jejunum (threefold decrease, P < 0.05) and ileum (2.5-fold decrease, P < 0.05), and mucosal protein in jejunum (twofold decrease, P < 0.05) compared to SBS-untreated animals (Group B). Treatment with TGF-β resulted in a mild decrease in enterocyte proliferation in jejunum (25%, P < 0.05) and ileum (18%, P < 0.05). A decreased cell apoptosis in the SBS-TGF-β group was accompanied by a decreased Bax and increased Bcl-2 mRNA expression.Conclusions: In a rat model of SBS, dietary TGF-β inhibits intestinal adaptation. Decreased enterocyte proliferation is responsible for this effect. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that the adipose tissue-derived cytokine leptin (LEP) is involved in modulation of growth and differentiation of normal small intestine. The purpose of the present study was to evaluate the effects of parenteral LEP on structural intestinal adaptation, cell proliferation and apoptosis in a rat model of short bowel syndrome (SBS). Male Sprague-Dawley rats were divided into three experimental groups: Sham rats underwent bowel transection and re-anastomosis, SBS-rats underwent a 75% small bowel resection, and SBS-LEP-rats underwent bowel resection and were treated with LEP given subcutaneously at a dose of 20 μg/kg, once daily, from day 3 through 14. Parameters of intestinal adaptation (bowel and mucosal weights, mucosal DNA and protein, villus height and crypt depth in jejunum and ileum), enterocyte proliferation and enterocyte apoptosis were determined on day 15 following operation. Ileal tissue samples were taken for detection of bax and bcl-2 gene expression using RT-PCR technique. Statistical analysis was performed using the non-parametric Kruskal–Wallis ANOVA test, with P<0.05 considered statistically significant. Treatment with subcutaneous LEP resulted in a significant increase in jejunal (17%, P<0.05) and ileal (13%, P<0.05) bowel weight, jejunal (10%, P<0.05) and ileal (25%, P<0.05) mucosal weight, jejunal (26%, P<0.05) and ileal (38%, P<0.05) mucosal DNA, ileal (25%, P<0.05) mucosal protein, jejunal (41%, P<0.05) and ileal (21%, P<0.05) villus height, jejunal (37%, P<0.05) crypt depth, and jejunal (24%, P<0.05) and ileal (21%, P<0.05) enterocyte proliferation compared to SBS-animals. Enterocyte apoptosis increased significantly after bowel resection in jejunum and ileum compared to sham animals and was accompanied by an increased bax gene expression and a decreased bcl-2 gene expression in ileal samples. SBS-LEP rats showed a trend toward a decrease in enterocyte apoptosis in ileum and a mild decrease in bax gene expression compared to SBS-untreated animals. In conclusion, in a rat model of SBS parenteral LEP stimulates structural intestinal adaptation. Increased cell proliferation and decreased cell death via apoptosis may be responsible for this increased cell mass. [ABSTRACT FROM AUTHOR]

Massive small bowel resection (SBR) results in a significant increase in intestinal epithelial cell (EC) proliferation as well as apoptosis. Because the site of SBR (proximal (P) vs. distal (D)) affects the degree of intestinal adaptation, we hypothesized that different rates of EC apoptosis would also be found between P-SBR and D-SBR models. Wild-type C57BL/6J mice underwent: (1) 60% P-SBR, (2) 60% D-SBR, or (3) SHAM-operation (transaction-reanastomosis) at the mid-gut point. Mice were sacrificed after 7 days. EC apoptosis was measured by TUNEL staining. EC-related apoptotic gene expression including intrinsic and extrinsic pathways was measured with reverse transcriptase-polymerase chain reaction. Bcl-2 and bax protein expression were analyzed by Western immunoblotting. Both models of SBR led to significant increases in villus height and crypt depth; however, the morphologic adaptation was significantly higher after P-SBR compared to D-SBR (P<0.01). Both models of SBR led to significant increases in enterocyte apoptotic rates compared to respective sham levels; however, apoptotic rates were 2.5-fold higher in ileal compared to jejunal segments (P<0.01). P-SBR led to significant increases in bax (pro-apoptotic) and Fas expression, whereas D-SBR resulted in a significant increase in TNF-alpha expression (P<0.01). EC apoptosis seems to be an important component of intestinal adaptation. The significant difference in EC apoptotic rates between proximal and distal intestinal segments appeared to be due to utilization of different mechanisms of action. [ABSTRACT FROM AUTHOR]

Background: The intestinal adaptive response [increased epithelial cell (EC) proliferation and apoptosis] after massive small bowel resection (SBR) is partially controlled by intraepithelial lymphocytes (IEL). To identify IEL factors contributing to EC adaptation post-SBR we utilized microarray assays.Methods: Mice underwent a 70% SBR (SBR1w/SBR4w) or sham operation (Sham1w/Sham4w). After 1 or 4 weeks (1w, 4w) small bowel was harvested, and IEL isolated. Determination of the EC-proliferation rate used BrdU incorporation, and of the EC-apoptotic rate used Annexin V staining. Affymetrix system microarrays (12,491 genes) were performed to examine IEL-mRNA expression. Results were considered significant if fold-change (FC) between groups was >2 and P<0.05 (F-test), or FC>3 and 0.05> P >0.01, or FC>4 and P>0.05. Significant genes were confirmed by conventional RT-PCR.Results: The SBR EC-proliferation rate increased significantly in both 1w and 4w groups compared to Sham: SBR1w 0.24+/-0.07 vs. Sham1w 0.12+/-0.02 (P=0.03); SBR4w 0.35+/-0.04 vs. Sham4w 0.19+/-0.02 ( P<0.01). The EC-apoptotic rate was unchanged in the 1w group, but significantly differed from controls after 4 weeks: SBR4w 39.92+/-6.78 vs. Sham4w 12.56+/-6.44 ( P<0.01). Microarray results were analyzed to identify potential growth-modifying IEL genes. The following were identified (function in parenthesis; A, apoptosis; P, proliferation): lipocalin 2 (promotes A), angiotensin converting enzyme (increases A), Rap2 interacting protein (reduces A, promotes P), amphiregulin (promotes P) and leucine-rich-alpha2-glycoprotein (promotes A, reduces P). Based on RT-PCR results these genes showed significant changes between groups. The increase in ACE at 1w preceded the observed apoptotic changes. The alterations in lipocalin 2, Rap2 and amphiregulin at 4w coincided with the marked changes in growth and apoptosis in the SBR mice.Conclusions: IEL undergo temporal changes after SBR. These findings provide profound insight into potential IEL-dependent regulation of EC homeostasis post-SBR. [ABSTRACT FROM AUTHOR]