Functional outcome after restorative proctocolectomy in pigs: comparing a novel transverse ileal pouch to the J-pouch and straight ileoanal anastomosis

BACKGROUND

Restorative proctocolectomy followed by an ileoanal J-pouch procedure is the therapy of choice for patients with familial adenomatous polyposis and ulcerative colitis. After low anterior rectal resection, the authors have reported on a novel, less complex pouch configuration, a transverse coloplasty pouch. The aim of the present work was to apply this new design to the ileal pouch construction, to evaluate feasibility, and to measure functional results in comparison with the J-pouch and the straight ileoanal anastomosis using the pig as an animal model.

METHODS

Twenty-three pigs underwent restorative proctocolectomy followed by reconstruction with straight ileoanal anastomosis (IAA; n = 5), J-pouch (n = 7), and a transverse ileal pouch (TIP; n = 11). Pigs were followed for 6 days postoperatively. Peristaltic function was assessed by manometry proximal to the pouch, in the reservoir, and at the level of the ileoanal anastomosis. Functional outcome was monitored by semiquantitative assessment of the general condition of the animals, postoperative feeding habits, and stool frequency and consistency. A Fourier analysis was performed in order to compare peristalsis in the ileal reservoirs. The reservoir volume was measured in situ by triple contrast computed tomography scan with 3D reconstruction.

RESULTS

Seventeen animals survived for 1 week. There was no difference in the general condition or the feeding habits of the groups. A significant number of pigs with the TIP pouch (7/10) had semisolid or formed stools as opposed to liquid stools after J-pouch (6/6) and IAA (4/5; p = 0.01). TIP animals had a lower stool frequency (3.2 +/- 1.14 per day) on day 6 after the operation than pigs with J-pouch, 5.33 +/- 1,03, and IAA, 4.6 +/- 1.82 (p = 0.0036). The in situ volume of the pouches did not differ significantly. The Fourier analysis demonstrated a disruption of peristalsis by the J-pouch and the TIP reconstruction but not after IAA.

CONCLUSION

The function of ileoanal reservoirs after proctocolectomy may result from the disruption of properistaltic waves after pouch formation. The mechanism of peristalsis disruption is independent of the in situ volume of the pouch.

Potential target antigens for immunotherapy in human pancreatic cancer

BACKGROUND

To be effective and selective, immunotherapy ideally targets specifically tumor cells and spares normal tissues. Identification of tumor specific antigens is a prerequisite to establish an effective immunotherapy. Still very little is known about the expression of tumor-related antigens in pancreatic neoplasms. Cancer Testis antigens (CT) are antigens shared by a variety of malignant tumors, but not by normal tissues with the exception of germ cells in testis. Restricted expression in neoplastic tissues and inherent immunogenic features make CT antigens ideal for use in immunotherapy. We analyzed the expression of a selected panel of nine CT antigens that have been proven to elicit an efficient immunogenic response in other malignancies. In addition we analyzed the expression of HERV-K-MEL, an immunogenic antigen of viral origin.

METHODS

Pancreatic adenocarcinoma tumor samples (n=130) were obtained intraoperatively, control tissues (n=23) were collected from cadaveric donor and from patients with chronic pancreatitis. Tumor-associated antigen expression of MAGE-A1, MAGE-A3, MAGE-A4, MAGE-A10, LAGE-1, NY-ESO-1, SCP-1, SSX-2, SSX-4 and HERV-K-MEL was assessed by PCR. Sequencing of PCR products were performed to assess the expression of SSX-4 in neoplastic and normal pancreatic tissues.

RESULTS

Three of 10 tested antigens were expressed in over 10% of malignant pancreatic tissue samples. SSX-4 was found positive in 30% of cases, SCP-1 in 19% and HERV-K-MEL in 23% of cases. No expression of CT antigens was found in non-malignant pancreatic tissue with the exception of SSX-4 and and SSX-2.

CONCLUSIONS

Fifty two percentage of the analyzed tissues expressed at least one CT antigen. The concomitant expression of SSX-4 in both malignant and non-malignant pancreatic tissue is a new finding which may raise concerns for immunotherapy. However, HERV-K-MEL is expressed with a relatively high prevalence and may be a candidate for specific immunotherapy in a large subgroup of pancreatic cancer patients. This study advocates the analysis of patients with regard to their immunogenic profile before the onset of antigen-specific immunotherapy.

Specific immune recognition of pancreatic carcinoma by patient-derived CD4 and CD8 T cells and its improvement by interferon-gamma

Pancreatic carcinoma is a very aggressive disease and little is known about its immunobiology. We here describe the presence in pancreatic cancer patients of spontaneously induced functional CD4 and CD8 memory/effector T cells reactive to autologous tumor cells or to the pancreatic cancer associated antigen, MUC-1. Such specific cells were present in the bone marrow or peripheral blood of most of the 23 tested patients. Low dose stimulation of primary cultures of pancreatic cancer cells with 500 IU/ml IFN-gamma for 72 h enhanced HLA-I expression and induced the de novo expression of HLA-II molecules. This led to a much better immune recognition by autologous HLA-I restricted and purified CD8 T cells and allowed tumor cell recognition by HLA-II restricted purified CD4 T-helper cells. Thus, interferon-gamma appears to be a useful adjuvant cytokine to enhance the immunogenicity of a patients' tumor cells and their recognition by tumor reactive immune cells.

An endothelium-derived hyperpolarizing factor distinct from NO and prostacyclin is a major endothelium-dependent vasodilator in resistance vessels of wild-type and endothelial NO synthase knockout mice

In addition to nitric oxide (NO) and prostacyclin (PGI(2)), the endothelium generates the endothelium-derived hyperpolarizing factor (EDHF). We set out to determine whether an EDHF-like response can be detected in wild-type (WT) and endothelial NO synthase knockout mice (eNOS -/-) mice. Vasodilator responses to endothelium-dependent agonists were determined in vivo and in vitro. In vivo, bradykinin induced a pronounced, dose-dependent decrease in mean arterial pressure (MAP) which did not differ between WT and eNOS -/- mice and was unaffected by treatment with N(omega)-nitro-l-arginine methyl ester and diclofenac. In the saline-perfused hindlimb of WT and eNOS -/- mice, marked N(omega)-nitro-l-arginine (l-NA, 300 micromol/liter)- and diclofenac-insensitive vasodilations in response to both bradykinin and acetylcholine (ACh) were observed, which were more pronounced than the agonist-induced vasodilation in the hindlimb of WT in the absence of l-NA. This endothelium-dependent, NO/PGI(2)-independent vasodilatation was sensitive to KCl (40 mM) and to the combination of apamin and charybdotoxin. Gap junction inhibitors (18alpha-glycyrrhetinic acid, octanol, heptanol) and CB-1 cannabinoid-receptor agonists (Delta(9)-tetrahydrocannabinol, HU210) impaired EDHF-mediated vasodilation, whereas inhibition of cytochrome P450 enzymes, soluble guanylyl cyclase, or adenosine receptors had no effect on EDHF-mediated responses. These results demonstrate that in murine resistance vessels the predominant agonist-induced endothelium-dependent vasodilation in vivo and in vitro is not mediated by NO, PGI(2), or a cytochrome P450 metabolite, but by an EDHF-like principle that requires functional gap junctions.

Increased nitrovasodilator sensitivity in endothelial nitric oxide synthase knockout mice: role of soluble guanylyl cyclase

Endogenously produced nitric oxide (NO) modulates nitrovasodilator-induced relaxation. We investigated the underlying mechanism in wild-type (WT) mice and endothelial NO synthase knockout (eNOS(-/-)) mice to determine whether a chronic lack of endothelial NO alters the soluble guanylyl cyclase (sGC) pathway. In aortic segments from eNOS(-/-) mice, the vasodilator sensitivity to sodium nitroprusside (SNP) was significantly greater than that in WT mice. There was no difference in sensitivity to the G-kinase I activator 8-para-chlorophenylthio-cGMP or to cromakalim. N(omega)-Nitro-L-arginine had no effect on the SNP-induced relaxation in eNOS(-/-) but increased the sensitivity in WT mice so it was no longer different than that of eNOS(-/-). Basal cGMP levels in aortic rings were significantly lower in eNOS(-/-) mice than in WT mice. SNP (300 nmol/L) induced a significantly greater cGMP accumulation in eNOS(-/-) mice than in WT mice. The maximal SNP-induced (10 micromol/L) increase in cGMP was similar in both strains. SNP-stimulated sGC activity was significantly greater in eNOS(-/-) mice than in WT mice. Incubation of aortic segments from WT mice with N(omega)-nitro-L-arginine increased sGC activity, an effect prevented by coincubation with SNP (10 micromol/L). The aortic expressions of the sGC alpha1 and beta1 subunits in WT and eNOS(-/-) mice were identical as determined with Western blot analysis. These data suggest that chronic exposure to endothelium-derived NO, as well as acute exposure to nitrovasodilator-derived NO, desensitizes sGC to activation by NO but does not alter sGC expression. Both the acute cessation of endothelial NO formation in WT mice and the chronic deficiency of NO in eNOS(-/-) mice restore the NO sensitivity of sGC and enhance vascular smooth muscle relaxation in response to nitrovasodilator agents.