Faculty Bibliography

OBJECTIVES: In adults, the premalignant nature of ulcerative colitis (UC) has long been accepted. Currently there is increasing concern that Crohn's disease (CD) may be equally premalignant. As a consequence, most adults with long-standing UC and many with chronic CD are enrolled in ongoing endoscopic cancer surveillance programs. In contrast, the risk of colonic cancer in adolescents and young adults with either form of colitis is less well recognized, and the need for dysplasia and cancer screening in this population has not been systematically evaluated. We therefore report the prospective results of colonoscopic cancer screening in such a young population. METHODS: Thirty-five adolescents and young adults with long-standing colitis (18 UC, 17 CD; 21 +/- 3 yr old, 11 +/- 3 yr colitis duration) underwent colonoscopic cancer screening. All had multiple biopsies for flow cytometry and light microscopy. RESULTS: Seven subjects had aneuploidy (3/18 UC, 4/17 CD). Of these seven, only two had dysplasia [one high grade (UC), one low grade (CD)]. One additional subject had indefinite dysplasia with normal flow cytometry. The remaining 27 subjects had both normal flow cytometry and light microscopy. Five of the seven aneuploid subjects underwent surgery within 1 yr of screening. Four, including both subjects with dysplasia, had no evidence of colon cancer at surgery. However, a 24-yr-old female with a 14-yr history of UC and no evidence of dysplasia or cancer at screening had a Dukes C adenocarcinoma. CONCLUSIONS: Adolescents and young adults with childhood onset UC or CD are at risk for aneuploidy, dysplasia, and colon cancer. Aneuploidy can be evident 10 yr after the onset of colitis and in patients as young as 16 yr of age. Therefore, the risk for colon cancer in patients with childhood onset colitis must be based on the duration of the illness, not on their chronological age. Incorporation of flow cytometry into an endoscopic screening protocol appears to enhance the ability to identify individuals at highest risk for colon cancer

To identify disease-specific T cell changes that occur in Crohn's disease (CD), the T cell receptor BV repertoires of lamina propria lymphocytes (LPL) isolated from both the inflamed and "disease-inactive" colons of seven CD patients were compared by the quantitative PCR and DNA sequence analysis. It was observed that the BV repertoires of LPL isolated from the disease-active and disease-inactive parts of the colon from the same individual were very different. Furthermore, nearly all of the differences occurred in CD4+ LPL, with very few differences in the CD8+ population of LPL. Although the pattern of BV segments that was increased in disease-active tissue relative to disease-inactive tissue was different for all seven CD patients, there were several BV segments that increased uniformly in the disease-active tissue of all seven individuals. CDR3 length analysis and DNA sequencing of these BV segments revealed that in six of the seven CD patients there was a striking degree of oligoclonality that was absent from disease-inactive tissue of the same individual. These observations suggest that at least some of the inflammation in CD is the result of responses by CD4+ T cells to specific antigens. The isolation of such inflammation-specific CD4+ T cells may make it possible to identify the antigens that are responsible for the inflammatory process in CD and provide a better understanding of its pathogenesis.

: Crohn's disease (CD) and ulcerative colitis (UC) are idiopathic inflammatory bowel diseases (IBD) that are characterized by chronic intestinal inflammation and are associated with abnormalities of peripheral and mucosal immune function. The aim of our study was to determine whether CD or UC is characterized by discrete profiles of intestinal lymphokine production. Total cellular RNA was isolated from biopsies of healthy controls and from patients with IBD. Messenger RNA transcript levels in biopsies were determined for interleukin-2 (IL-2), IL-4, IL-5, and interferon-gamma (IFN-gamma), using a quantitative reverse transcriptase polymerase chain reaction method. Compared with inflamed UC mucosa and controls, CD mucosal lesions contained higher IL-2 and IFN-gamma mRNA (p < 0.05), which is consistent with a T-helper cell 1 (Th1)-like pattern. In UC, IL-5 mRNA content was higher in involved areas compared with controls (p < 0.05) and inflamed CD lesions (p < 0.05), suggestive of a Th2 pattern. We conclude that the intestinal mucosa of CD and UC have inflammatory responses characterized by discrete T-helper profiles of lymphokines. This strongly suggests that the immunopathogenesis of these two forms of IBD are different.

To identify disease-specific T cell changes that occur in Crohn's disease (CD) the T-cell receptor (TCR) BV repertoires of lamina propria lymphocytes (LPL) from both disease-active and disease-inactive colonic tissue of three CD patients were compared by a quantitative polymerase chain reaction (qPCR) and CDR3 length analysis. It was observed that the BV repertoires of LPL isolated from the disease-active and disease-inactive parts of the colon of the same individual were different, and most of the differences occurred in CD4+ LPL with very few differences in the CD8+ populations of LPL. Although the pattern of BV segments that was increased in disease-active relative to disease-inactive tissue was different for all three CD patients, there was an increase in the levels of BV11, 13S2, 15, 16, and 17 segments in the disease-active tissue of all three patients. Standard CDR3 length analysis of BV11, 13S2, 15, 16, and 17 segments revealed that in two of the three CD patients there was a striking degree of TCR oligoclonality in the disease-active tissue that was absent from disease-inactive tissue of the same individual. Additional differences between the disease-active and disease-inactive tissues were observed using a more refined method of CDR3 length analysis, which employs BV- and BJ-specific primers. These observations suggest that at least some of the inflammation in CD is the result of responses by CD4+ T cells to specific antigens.

Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation whose cellular components are capable of oxidative respiratory bursts that may result in tissue injury. Mucosal biopsies were analyzed for protein carbonyl content (POPs), DNA oxidation products [8-hydroxy-2'-deoxyguanosine (8-OHdG)], reactive oxygen intermediates (ROIs), trace metals (copper, zinc, and iron) and superoxide dismutase (Cu-Zn SOD). In Crohn's disease biopsies, there was an increase in ROIs, POPs, 8-OHdG, and iron, while decreased copper and Cu-Zn SOD activity were found in inflamed tissues compared to controls. For ulcerative colitis, there was an increase in ROIs, POPs, and iron in inflamed tissue compared to controls, while decreased zinc and copper were observed. An imbalance in the formation of reactive oxygen species and antioxidant micronutrients may be important in the pathogenesis and/or perpetuation of the tissue injury in IBD and may provide a rationale for therapeutic modulation with antioxidants

Hyposplenism as a complication of celiac sprue confers an increased risk of pneumococcal sepsis, but such patients do not routinely receive pneumococcal vaccine despite reports of overwhelming pneumococcal sepsis. Because antibody response in these patients has not been previously assessed, we measured pre- and postvaccination levels in 10 patients with documented sprue. All demonstrated appropriate acute antibody responses to a polyvalent pneumococcal vaccine. Vaccination of all patients with celiac sprue seems appropriate.