Impact of immunosuppression on the incidence of early subclinical renal allograft rejection: implications for protocol biopsy policy

In order to determine the impact of immunosuppression (IS) on the incidence of early subclinical rejection (SCR), we studied two groups of patients receiving different immunosuppressive regimens. Patients received cyclosporin (CsA), azathioprine and prednisolone (group 1; n  = 304) or IS according to immunological risk (group 2; n  = 150). The highest-risk patients received basiliximab induction, tacrolimus, mycophenolate mofetil (MMF) and prednisolone; medium-risk patients CsA, MMF and prednisolone; low-risk CsA, azathioprine and prednisolone. Protocol biopsies were performed in all patients, irrespective of graft function, on days 7 and 28 post-transplantation. Only patients with good stable function at the time of biopsy were included for assessment of SCR. Group 2 patients showed significant reductions in total rejection frequency (32.6% vs. 57.2%, P  = <0.0001) and SCR frequency in day 7 protocol biopsies (2% vs. 13%, P  = <0.05). In group 2 patients, all SCRs, but not borderline changes, were treated. Untreated borderline changes did not have an adverse impact on graft function at 1 year post-transplantation. New immunosuppressive regimens may reduce subclinical in addition to clinical rejection-frequency, suggesting that the relative benefit of early protocol biopsies in detecting SCR is also reduced.     

Depressive symptomatology correlates with phantom breast syndrome in mastectomized women

OBJECTIVE: Phantom breast syndrome (PBS) after mastectomy has been hypothesized to represent a complex psychological reaction to mastectomy, but psychological studies concerning PBS are few and inconclusive. This study aimed to assess possible correlations of PBS to current psychopathology and personality dimensions, as well as to examine subjectively experienced provoking and relieving factors for the experience of PBS. METHOD: A total of 105 women who had undergone modified radical mastectomy were interviewed by a structured questionnaire after breast surgery. Moreover, they completed a set of self-administered psychometric scales consisting of Symptom Checklist-90-R, Eysenck personality questionnaire, Zung depression scale, State-Trait Anxiety Inventory and Whiteley Index of hypochondriasis. RESULTS: PBS was experienced by 24 women (22.9%). The majority of them thought that PBS did not interfere with their everyday life. Women with PBS scored significantly higher on the Zung depression scale. Multiple logistic regression analysis revealed that women aged more than 66 years were 82% less likely to have PBS compared to those aged less than 51 years. CONCLUSION: These findings provide evidence that PBS is associated with higher scores of depressive symptomatology and younger age. The nature of such an association remains unclear and calls for further investigation.     

Comparative efficacies of rifaximin and vancomycin for treatment of Clostridium difficile-associated diarrhea and prevention of disease recurrence in hamsters

Clostridium difficile-associated colitis is an increasing cause of morbidity and mortality in hospitalized patients, with high relapse rates following conventional therapy. We sought to determine the efficacy of rifaximin, a novel nonabsorbed antibiotic, in the hamster model of C. difficile-associated diarrhea (CDAD). Hamsters received clindamycin subcutaneously and 24 h later were infected by gavage with one of two C. difficile strains: a reference strain (VPI 10463) and a current epidemic strain (BI17). Vancomycin (50 mg/kg of body weight) or rifaximin (100, 50, and 25 mg/kg) were then administered orally for 5 days beginning either on the same day as infection (prevention) or 24 h later (treatment). Therapeutic effects were assessed by weight gain, histology, and survival. We found that rifaximin was as effective as vancomycin in the prevention and treatment of colitis associated with the two C. difficile strains that we examined. There was no relapse after treatment with vancomycin or rifaximin in hamsters infected with the BI17 strain. Hamsters infected with the VPI 10463 strain and treated with rifaximin did not develop relapsing infection within a month of follow-up, whereas the majority of vancomycin-treated animals relapsed (0% versus 75%, respectively; P < 0.01). In conclusion, rifaximin was found to be an effective prophylactic and therapeutic agent for CDAD in hamsters and was not associated with disease recurrence. These findings, in conjunction with the pharmacokinetic and safety profiles of rifaximin, suggest that it is an attractive candidate for clinical use for CDAD.     

Induction of colitis causes inflammatory responses in fat depots: evidence for substance P pathways in human mesenteric preadipocytes

Intracolonic administration of trinitrobenzene sulfonic acid in mice causes inflammation in the colon that is accompanied by increased expression of proinflammatory cytokines and of the substance P (SP), neurokinin 1 receptor (NK-1R) in the proximal mesenteric fat depot. We also investigated whether human mesenteric preadipocytes contain NK-1R and examined the functional consequences of exposure of these cells to SP as it relates to proinflammatory signaling. We found that human mesenteric preadipocytes express NK-1R both at the mRNA and protein levels. Exposure of human mesenteric preadipocytes to SP increased NK-1R mRNA and protein expression by 3-fold, and stimulated IL-8 mRNA expression and protein secretion. This effect was abolished when these cells were pretreated with the specific NK-1R antagonist CJ 012,255. Moreover, human mesenteric preadipocytes transfected with a luciferase promoter/reporter system containing the IL-8 promoter with a mutated NF-kappaB site lost their ability to respond to SP, indicating that SP-induced IL-8 expression is NF-kappaB-dependent. This report indicates that human mesenteric preadipocytes contain functional SP receptors that are linked to proinflammatory pathways, and that SP can directly increase NK-1R expression. We speculate that mesenteric fat depots may participate in intestinal inflammatory responses via SP-NK-1R-related pathways, as well as other systemic responses to the presence of an ongoing inflammation of the colon.     

The neurotensin receptor-1 promotes tumor development in a sporadic but not an inflammation-associated mouse model of colon cancer

Neurotensin receptor-1 (NTR-1) is overexpressed in colon cancers and colon cancer cell lines. Signaling through this receptor stimulates proliferation of colonocyte-derived cell lines and promotes inflammation and mucosal healing in animal models of colitis. Given the causal role of this signaling pathway in mediating colitis and the importance of inflammation in cancer development, we tested the effects of NTR-1 in mouse models of inflammation-associated and sporadic colon cancer using NTR-1-deficient (Ntsr1(-) (/-)) and wild-type (Ntsr1(+/+)) mice. In mice treated with azoxymethane (AOM) to model sporadic cancer, NTR-1 had a significant effect on tumor development with Ntsr1(+/+) mice developing over twofold more tumors than Ntsr1(-) (/-) mice (p = 0.04). There was no effect of NTR-1 on the number of aberrant crypt foci or tumor size, suggesting that NT/NTR-1 signaling promotes the conversion of precancerous cells to adenomas. Interestingly, NTR-1 status did not affect tumor development in an inflammation-associated cancer model where mice were treated with AOM followed by two cycles of 5% dextran sulfate sodium (DSS). In addition, colonic molecular and histopathologic analyses were performed shortly after a single cycle of DSS. NTR-1 status did not affect colonic myeloperoxidase activity or histopathologic scores for damage and inflammation. However, Ntsr1(-) (/-) mice were more resistant to DSS-induced mortality (p = 0.01) and had over twofold higher colonic expression levels of Il6 and Cxcl2 (p < 0.04), cytokines known to promote tumor development. These results represent the first direct demonstration that targeted disruption of the Ntsr1 gene reduces susceptibility to colon tumorigenesis.     

CP-96,345, a substance P antagonist, inhibits rat intestinal responses to Clostridium difficile toxin A but not cholera toxin.

Toxin A from Clostridium difficile mediates acute inflammatory enterocolitis in experimental animals, while cholera toxin causes noninflammatory secretory diarrhea. The purpose of this study was to investigate whether an antagonist to the peptide substance P, a constituent of primary sensory neurons known to participate in inflammatory responses, would inhibit toxin A-mediated enteritis in the rat ileum. Pretreatment of rats with CP-96,345 (2.5 mg per kg of body weight), a substance P antagonist, dramatically inhibited fluid secretion (P < 0.01) and mannitol permeability (P < 0.01) in ileal loops exposed to toxin A. The protective effects, which were dose dependent, caused a significant reduction of inflammation in the lamina propria, reduction of the necrosis of intestinal epithelial cells, and complete inhibition of toxin A-mediated release of rat mast cell protease II, a specific product of rat mucosal mast cells. An inactive enantiomer of the substance P antagonist, CP-96,344, had no effect. In contrast, pretreatment with CP-96,345 had no inhibitory effect on the intestinal effects caused by administration of cholera toxin into the ileal loops. From these data, we conclude that the peptide substance P is involved in the secretory and inflammatory effects of toxin A but not of cholera toxin.     

Melanin-concentrating hormone as a mediator of intestinal inflammation

Melanin-concentrating hormone (MCH) is expressed primarily in the hypothalamus and has a positive impact on feeding behavior and energy balance. Although MCH is expressed in the gastrointestinal tract, its role in this system remains elusive. We demonstrate that, compared to wild type, mice genetically deficient in MCH had substantially reduced local inflammatory responses in a mouse model of experimental colitis induced by intracolonic administration of 2,4,6 trinitrobenzene sulfonic acid (TNBS). Likewise, mice receiving treatments with an anti-MCH antibody, either prophylactically or after the establishment of colitis, developed attenuated TNBS-associated colonic inflammation and survived longer. Consistent with a potential role of MCH in intestinal pathology, we detected increased colonic expression of MCH and its receptor in patients with inflammatory bowel disease. Moreover, we found that human colonic epithelial cells express functional MCH receptors, the activation of which induces IL-8 expression. Taken together, these results clearly implicate MCH in inflammatory processes in the intestine and perhaps elsewhere.     

Clostridium difficile toxin B disrupts the barrier function of T84 monolayers.

The contribution of toxin B to Clostridium difficile-associated infection is undefined. Toxin B induces dramatic phenotypic alterations (cytotoxic effects) in cultured mesenchymal and nonintestinal epithelial cells, yet its effects on intestinal epithelial cells are not clearly understood. The alterations induced by toxin B in nonintestinal cells appear to be secondary to toxin-induced redistribution of filamentous actin. It has not been determined whether toxin B exerts similar effects on cultured intestinal epithelial cells or whether such phenotypic alterations are of any physiological consequence. To address these questions, we examined the effect of C. difficile toxin B on the phenotype and barrier function of T84 cell monolayers. Our studies show that the cytotoxic effects of toxin B, i.e., cell rounding, do extend to cultured intestinal epithelial cells (T84). In addition, toxin B dramatically reduces the barrier function of T84 monolayers grown on collagen-coated filters. Toxin B-induced redistribution of filamentous actin appears to be responsible for the alterations in both intestinal epithelial cell phenotype and barrier function. Specifically, filamentous actin comprising the perijunctional actomyosin ring, known to be important in regulating tight junction permeability, is condensed into discrete plaques. Flux studies confirm that the permeability defect is at the level of the tight junction. We conclude that toxin-induced changes in actin distribution perturb intercellular junctional contacts and thereby ablate epithelial barrier function. There was no evidence of cell death as determined by lactate dehydrogenase release assays.     

Adipose tissue and inflammatory bowel disease pathogenesis

Creeping fat has long been recognized as an indicator of Crohn's disease (CD) activity. Although most patients with CD have normal or low body mass index (BMI), the ratio of intraabdominal fat to total abdominal fat is far greater than that of controls. The obesity epidemic has instructed us on the inflammatory nature of hypertrophic adipose tissue and similarities between mesenteric depots in obese and CD patients can be drawn. However, several important physiological differences exist between these two depots as well. While the molecular basis of the crosstalk between mesenteric adipose and the inflamed intestine in CD is largely unknown, novel evidence implicates neuropeptides along with adipocyte-derived paracrine mediators (adipokines) as potential targets for future investigations and highlight adipose tissue physiology as a potential important determinant in the course of IBD.     

Levamisole inhibits intestinal Cl secretion via basolateral K channel blockade

Background & Aims: Phenylimidazothiazoles have recently been shown to activate wild-type and mutant cystic fibrosis transmembrane conductance regulator (CFTR) Cl⁻ channels in transfected cells and were proposed as therapy for cystic fibrosis. The aim of this study was to investigate the effects of phenylimidazothiazoles on regulated transepithelial Cl⁻ transport in intact epithelia. Methods: T84 intestinal epithelial cells grown on permeable supports and stripped human colonic mucosal sheets were studied by conventional current-voltage clamping. Selective permeabilization of apical or basolateral membranes with the monovalent ionophore nystatin was used to isolate basolateral K⁺ and apical Cl⁻ channel activity, respectively. ⁸⁶Rb⁺ uptake was assessed for Na/K/2Cl cotransporter and Na⁺,K⁺–adenosine triphosphatase activity. Results: In T84 monolayers and human colon, levamisole and its brominated derivative bromotetramisole failed to activate transepithelial secretion. In fact, these compounds dose-dependently inhibited secretory responses to the cyclic adenosine monophosphate agonist forskolin and the Ca²⁺ agonist carbachol. In permeabilized T84 monolayers, phenylimidazothiazoles weakly activated apical Cl⁻ currents (consistent with their reported action on CFTR) and did not affect bumetanide-sensitive or bumetanide-insensitive ⁸⁶Rb⁺ uptake. Instead, they profoundly inhibited the basolateral Ba²⁺-sensitive and Ba²⁺-insensitive K⁺ currents. Conclusions: Phenylimidazothiazoles block K⁺ channels required for Cl⁻-secretory responses elicited by diverse pathways in model epithelia and native colon, an effect that outweighs their ability to activate apical Cl⁻ channels.GASTROENTEROLOGY 1998;114:1257-1267