D O'Donoghue

Tissue cytokine and chemokine expression in inflammatory bowel disease

Abstract.Objective and design: This study aimed to determine if mucosal expression of the chemokines IL-8, RANTES and MCP-1 and the pro-inflammatory cytokines TNFα and IL-6 are elevated in patients with inflammatory bowel disease.¶Materials and subjects: Intestinal mucosa samples were obtained at the time of surgical resection, n=16 from each of the following groups: normal/control, CD and UC.¶Methods: An homogenate was prepared of each tissue sample and cytokines measured by ELISA.¶Results: IL-8 was significantly increased in both disease groups compared to controls Similarly, RANTES levels were also significantly increased. MCP-1 levels were increased in both disease groups, this increase was statistically significant in the UC group only. TNFα and IL-6 were significantly increased in the CD group only.¶Conclusions: Chemokines, together with key cytokines that promote their release are elevated in mucosal tissues from patients with IBD. It is likely that these chemokines play an important role in the perpetuation of tissue destructive inflammatory processes.

Development and Independent Validation of a Prognostic Assay for Stage II Colon Cancer Using Formalin-Fixed Paraffin-Embedded Tissue

PURPOSE Current prognostic factors are poor at identifying patients at risk of disease recurrence after surgery for stage II colon cancer. Here we describe a DNA microarray-based prognostic assay using clinically relevant formalin-fixed paraffin-embedded (FFPE) samples. PATIENTS AND METHODS A gene signature was developed from a balanced set of 73 patients with recurrent disease (high risk) and 142 patients with no recurrence (low risk) within 5 years of surgery. RESULTS The 634-probe set signature identified high-risk patients with a hazard ratio (HR) of 2.62 (P < .001) during cross validation of the training set. In an independent validation set of 144 samples, the signature identified high-risk patients with an HR of 2.53 (P < .001) for recurrence and an HR of 2.21 (P = .0084) for cancer-related death. Additionally, the signature was shown to perform independently from known prognostic factors (P < .001). CONCLUSION This gene signature represents a novel prognostic biomarker for patients with stage II colon cancer that can be applied to FFPE tumor samples.

Identifying stage B colorectal cancer patients at high risk of tumor recurrence and death.

PURPOSE: This study was designed to determine clinical and pathologic variables associated with poor outcome following resection of Stage B colorectal cancer. METHODS: This was a retrospective study of 117 patients with Stage B cancer who underwent curative surgery and survived the postoperative period. Fourteen clinical and pathologic features were studied. Clinical data were extracted from a prospective colorectal cancer database, and histologic slides were retreived and examined by a pathologist blinded as to clinical details and outcome. RESULTS: After a median follow-up period of 8.2 years, bowel obstruction was significantly related to a poor prognosis (log-rank test; P=0.03). Extensive necrosis (P=0.01) and perineural invasion (P= 0.03) were also associated with decreased survival. Vascular invasion was associated with poor long-term outcome in the subgroup of patients with rectal (P=0.07) but not colonic (P=0.57) cancer. Multivariate regression analysis identified both tumor necrosis (P=0.01) and perineural invasion (P=0.03) as independently related to outcome. CONCLUSION: Further study of prognostic indicators might result in an algorithm to distinguish Stage B cases at high risk of tumor recurrence and death. Such patients could be included in future trials of adjuvant therapies.

Diverse populations of T cells with NK cell receptors accumulate in the human intestine in health and in colorectal cancer

T cells expressing NK cell receptors (NKR) display rapid MHC‐unrestricted cytotoxicity and potent cytokine secretion and are thought to play roles in immunity against tumors. We have quantified and characterized NKR+ T cells freshly isolated from epithelial and lamina propria layers of duodenum and colon from 16 individuals with no evidence of gastrointestinal disease and from tumor and uninvolved tissue from 19 patients with colorectal cancer. NKR+ T cell subpopulations were differentially distributed in different intestinal compartments, and CD161+ T cells accounted for over one half of T cells at all locations tested. Most intestinal CD161+ T cells expressed α β TCR and either CD4 or CD8. Significant proportions expressed HLA‐DR,CD69 and Fas ligand. Upon stimulation in vitro, CD161+ T cells produced IFN‐γ and TNF‐α but not IL‐4. NKT cells expressing the Vα24Vβ11 TCR, which recognizes CD1d,were virtually absent from the intestine, but colonic cells produced IFN‐γ in response to the NKT cell agonist ligand α‐galactosylceramide. NKR+ T cells were not expanded in colonic tumors compared to adjacent uninvolved tissue. The predominance, heterogeneity and differential distribution of NKR+ T cells at different intestinal locations suggests that they are central to intestinal immunity.

Spatial variation of the colonic microbiota in patients with ulcerative colitis and control volunteers

Objectives The relevance of spatial composition in the microbial changes associated with UC is unclear. We coupled luminal brush samples, mucosal biopsies and laser capture microdissection with deep sequencing of the gut microbiota to develop an integrated spatial assessment of the microbial community in controls and UC. Design A total of 98 samples were sequenced to a mean depth of 31 642 reads from nine individuals, four control volunteers undergoing routine colonoscopy and five patients undergoing surgical colectomy for medically-refractory UC. Samples were retrieved at four colorectal locations, incorporating the luminal microbiota, mucus gel layer and whole mucosal biopsies. Results Interpersonal variability accounted for approximately half of the total variance. Surprisingly, within individuals, asymmetric Eigenvector map analysis demonstrated differentiation between the luminal and mucus gel microbiota, in both controls and UC, with no differentiation between colorectal regions. At a taxonomic level, differentiation was evident between both cohorts, as well as between the luminal and mucosal compartments, with a small group of taxa uniquely discriminating the luminal and mucosal microbiota in colitis. There was no correlation between regional inflammation and a breakdown in this spatial differentiation or bacterial diversity. Conclusions Our study demonstrates a conserved spatial structure to the colonic microbiota, differentiating the luminal and mucosal communities, within the context of marked interpersonal variability. While elements of this structure overlap between UC and control volunteers, there are differences between the two groups, both in terms of the overall taxonomic composition and how spatial structure is ascribable to distinct taxa.

Primary Sclerosing Cholangitis and Disease Distribution in Inflammatory Bowel Disease

BACKGROUND & AIMS The relationship between site of intestinal inflammation and primary sclerosing cholangitis (PSC) development in inflammatory bowel disease (IBD) has not been studied extensively, but may be important in understanding the pathogenesis of PSC. We aimed to determine patterns of disease distribution in IBD patients with and without PSC. METHODS We performed a 2-part study involving the following: (1) 2754 IBD patients and (2) 82 separate PSC patients attending the Irish National Liver Transplant Unit. RESULTS Fifty-nine of 2708 (2.2%) IBD patients had PSC. In ulcerative colitis patients, PSC incidence increased with increasing colonic involvement (P = .001) and was relatively rare in those without total colitis. Thirteen Crohns disease patients had PSC, none with isolated small-bowel disease had PSC (P = .03). In study 2, the majority of ulcerative colitis patients with PSC had total colitis, whereas the remainder had disease extending at least to the left colon. In addition, all 10 PSC patients with Crohns disease had colonic involvement. CONCLUSIONS An inflamed colon, but not small bowel, is important in PSC development and it is possible that bacterial translocation and subsequent portal bacteremia is important in PSC development in IBD.

Duration of colorectal cancer symptoms and survival: the effect of confounding clinical and pathological variables

The relationship between symptom duration and long-term survival following colorectal cancer is complex, and a number of factors may influence the length of time from onset of symptoms of cancer diagnosis. We prospectively studied 777 consecutive colorectal cancer patients to determine the association between symptom duration and survival independent of other clinical and pathological features. We used survival curves, the logrank test and Coxs proportional hazards model to assess possible changes in relative risk of death with increasing symptom duration, without making any a priori assumptions. We found that symptom duration shortened with advanced tumour stage (P < 0.0006) and was also shorter for patients presenting with bowel obstruction (P < 0.0001). Univariate survival analysis showed that long-term survival increased consistently with symptom duration (P < 0.001). However, when the effect of tumour stage and bowel obstruction were accounted for in a multivariate analysis, no decrease in the relative risk of death was seen as symptom duration increased. The addition of other variables to the proportional hazards model such as age, sex or tumour site did not further influence the risk function form of symptom duration. Our results suggest that early diagnosis of colorectal cancer should remain our goal when assessing patients with suggestive gastrointestinal symptoms.

Fulminant colitis in inflammatory bowel disease

PURPOSE: The morphologic features of fulminant colitis may be nonspecific, making differentiation between ulcerative colitis and Crohns disease difficult, even after colectomy. The aims of this study were 1) to identify histologic features that accurately differentiated ulcerative colitis, Crohns disease, and indeterminate colitis in fulminant colectomy specimens; 2) to determine how frequently subsequent clinical course altered the pathologic diagnosis; and 3) to evaluate the natural history of histologically diagnosed indeterminate colitis. METHODS: Ninety-five fulminant colectomy specimens were evaluated, of which 85 had an original diagnosis of fulminant inflammatory bowel disease. Complete pathologic material and comprehensive clinical follow-up information was available on 67 cases of inflammatory bowel disease. These were re-evaluated in a blinded fashion, and histopathologic features were compared with the original diagnosis and reviewed in the light of subsequent clinical behavior to reach a final diagnosis. RESULTS: Evaluation of macroscopic features was not helpful in differentiating ulcerative colitis from Crohns disease. Microscopic examination correctly diagnosed ulcerative colitis or Crohns disease in only 58 of 67 (87 percent) cases. A further three cases (4 percent) were definitively classified after correlation with clinical data, leaving a residual six cases that were diagnosed as indeterminate colitis. Granulomas and lymphoid aggregates were the two most specific indicators of Crohns disease. CONCLUSIONS: Histopathologic evaluation alone has limitations in the accurate classification of fulminant inflammatory bowel disease. Histologically diagnosed indeterminate colitis is a heterogeneous group that may include some patients who subsequently prove to have ulcerative colitis or Crohns disease.

Regulation of ion transport by histamine in human colon

Histamine, added to the basolateral side of voltage clamped human colon in vitro, induced a rapid onset, transient inward short circuit current which was concentration dependent over the range 0.01-3 mM. This response was largely due to electrogenic chloride section since it was virtually abolished by bumetanide or by chloride replacement in the bathing solutions. Responses were unaffected by amiloride or acetazolamide. Neither the histamine H2 receptor agonist dimaprit (1 mM) nor the histamine H3 receptor agonist S-(+)-alpha-methyl histamine (1 mM) altered short circuit current. Responses to histamine were significantly reduced by the histamine H1 receptor antagonist mepyramine (1-10 microM) but not altered by the histamine H2 receptor antagonist cimetidine (100 microM) or by the histamine H3 receptor antagonist thioperamide (1 microM). Short circuit current responses to histamine were not altered by tetrodotoxin (1 microM). Piroxicam (10 microM) and nordihydroguaiaretic acid (100 microM) were without effect when used individually but significantly reduced responses to histamine when used simultaneously. These results indicate that histamine stimulates chloride secretion across human colonic epithelium by a mechanism which is mediated exclusively via histamine H1 receptors. This action does not involve intrinsic nerves but appears to be dependent upon eicosanoid synthesis.

Berberine inhibits ion transport in human colonic epithelia.

The effects of berberine on ion transport in both human colonic mucosal epithelia and an intestinal epithelial cell line (T84) were examined. Berberine (concentration range 0-500 microM) reduced both basal and stimulated ion transport responses in human colonic mucosae in a manner which was non-specific for Ca2+ -or cAMP-mediated signals. Similarly, in cultured intestinal epithelial monolayers, berberine inhibited Ca2+ -and cAMP-mediated responses indicating an inhibitory activity directly at the level of the epithelium rather than an indirect effect through other mucosal element(s). Berberine did not alter the rate of generation of cAMP by adenylyl cyclase or the activity of protein kinase A, the effector enzyme of the cAMP pathway. Berberine inhibited carbachol-stimulated 86Rb+ efflux from T84 monolayers. Berberine also inhibited K+ conductance in apically-permeabilised re-sected mucosae. These results indicate i) that berberine exerts an anti-secretory action directly upon epithelial cells and ii) the mechanism of action may be at the level of blockade of K+ channels.