Fibrosis in ulcerative colitis is directly linked to severity and chronicity of mucosal inflammation.

BACKGROUND: Fibrosis in ulcerative colitis has remained largely unexplored despite its clinical implications. AIMS: This cross-sectional study was aimed at characterising the presence, anatomical location and degree of ulcerative colitis-associated fibrosis and its possible link to clinical parameters. METHODS: Seven hundred and six individual tissue cross-sections derived every 10 cm along the length of 89 consecutive Ulcerative colitis colectomy specimens were examined and compared to Crohn's disease colitis, diverticular disease and uninvolved areas from colorectal cancer patients. Degree of inflammation, fibrosis and morphometric measurements of all layers of the intestinal wall were evaluated. Three gastrointestinal pathologists independently assessed colon sections stained with haematoxylin and eosin, Masson trichrome and Sirius red. Clinical data were collected prospectively. RESULTS: Submucosal fibrosis was detected in 100% of ulcerative colitis colectomy specimens, but only in areas affected by inflammation. Submucosal fibrosis was associated with the severity of intestinal inflammation (Spearman correlations rho (95% confidence interval): 0.58 (P < 0.001) and histopathological changes of chronic mucosal injury, but not active inflammation. Colectomy for refractory disease rather than presence of dysplasia was associated with increased fibrosis and a thicker muscularis mucosae, whereas a thinner muscularis mucosae was associated with anti-tumour necrosis factor therapy. No feature on endoscopic mucosal biopsies could predict the underlying amount of fibrosis or the thickness of the muscularis mucosae. CONCLUSIONS: A significant degree of fibrosis and muscularis mucosae thickening should be considered as common complications of chronic progressive ulcerative colitis. These features may have clinical consequences such as motility abnormalities and increased wall stiffness.

Review article: breath analysis in inflammatory bowel diseases.

BACKGROUND: There is an urgent need for cheap, reproducible, easy to perform and specific biomarkers for diagnosis, differentiation and stratification of inflammatory bowel disease (IBD) patients. Technical advances allow for the determination of volatile organic compounds in the human breath to differentiate between health and disease. AIM: Review and discuss medical literature on volatile organic compounds in exhaled human breath in GI disorders, focusing on diagnosis and differentiation of IBD. METHODS: A systematic search in PubMed, Ovid Medline and Scopus was completed using appropriate keywords. In addition, a bibliography search of each article was performed. RESULTS: Mean breath pentane, ethane, propane, 1-octene, 3-methylhexane, 1-decene and NO levels were elevated (P < 0.05 to P < 10(-7)) and mean breath 1-nonene, (E)-2-nonene, hydrogen sulphide and methane were decreased in IBD compared to healthy controls (P = 0.003 to P < 0.001). A combined panel of 3 volatile organic compounds (octene, (E)-2-nonene and decene) showed the best discrimination between paediatric IBD and controls (AUC 0.96). Breath condensate cytokines were higher in IBD compared to healthy individuals (P < 0.008). Breath pentane, ethane, propane, isoprene and NO levels correlated with disease activity in IBD patients. Breath condensate interleukin-1ß showed an inverse relation with clinical disease activity. CONCLUSIONS: Breath analysis in IBD is a promising approach that is not yet ready for routine clinical use, but data from other gastrointestinal diseases suggest the feasibility for use of this technology in clinical practice. Well-designed future trials, incorporating the latest breath detection techniques, need to determine the exact breath metabolome pattern linked to diagnosis and phenotype of IBD.

Platelet-activating factor and distinct chemokines are elevated in mucosal biopsies of erosive compared with non-erosive reflux disease patients and controls.

BACKGROUND: A distinction between symptomatic non-erosive reflux disease (NERD) and erosive esophagitis (EE) patients is supported by the presence of inflammatory response in the mucosa of EE patients, leading to a damage of mucosal integrity. To explore the underlying mechanism of this difference, we assessed inflammatory mediators in mucosal biopsies from EE and NERD patients and compared them with controls. METHODS: Nineteen NERD patients, 15 EE patients, and 16 healthy subjects underwent endoscopy after a 3-week washout from PPI or H(2) antagonists. Biopsies obtained from the distal esophagus were examined by quantitative real-time polymerase chain reaction (qPCR) and multiplex enzyme-linked immunosorbent assay for selected chemokines and lyso-PAF acetyltransferase (LysoPAF-AT), the enzyme responsible for production of platelet-activating factor (PAF). KEY RESULTS: Expression of LysoPAF-AT and multiple chemokines was significantly increased in mucosal biopsies derived from EE patients, when compared with NERD patients and healthy controls. Upregulated chemokines included interleukin 8, eotaxin-1, -2, and -3, macrophage inflammatory protein-1α (MIP-1α), and monocyte chemoattractant protein-1 (MCP-1). LysoPAF-AT and the chemokine profile in NERD patients were comparable with healthy controls. CONCLUSIONS & INFERENCES: Levels of selected cytokines and Lyso-PAF AT were significantly higher in the esophageal mucosa of EE patients compared with NERD and control patients. This difference may explain the distinct inflammatory response occurring in EE patients' mucosa. In contrast, as no significant differences existed between the levels of all mediators in NERD and control subjects, an inflammatory response does not appear to play a major role in the pathogenesis of the abnormalities found in NERD patients.

Amino acid position 11 of HLA-DRß1 is a major determinant of chromosome 6p association with ulcerative colitis.

The major histocompatibility complex (MHC) on chromosome 6p is an established risk locus for ulcerative colitis (UC) and Crohn's disease (CD). We aimed to better define MHC association signals in UC and CD by combining data from dense single-nucleotide polymorphism (SNP) genotyping and from imputation of classical human leukocyte antigen (HLA) types, their constituent SNPs and corresponding amino acids in 562 UC, 611 CD and 1428 control subjects. Univariate and multivariate association analyses were performed, controlling for ancestry. In univariate analyses, absence of the rs9269955 C allele was strongly associated with risk for UC (P = 2.67 × 10(-13)). rs9269955 is a SNP in the codon for amino acid position 11 of HLA-DRß1, located in the P6 pocket of the HLA-DR antigen binding cleft. This amino acid position was also the most significantly UC-associated amino acid in omnibus tests (P = 2.68 × 10(-13)). Multivariate modeling identified rs9269955-C and 13 other variants in best predicting UC vs control status. In contrast, there was only suggestive association evidence between the MHC and CD. Taken together, these data demonstrate that variation at HLA-DRß1, amino acid 11 in the P6 pocket of the HLA-DR complex antigen binding cleft is a major determinant of chromosome 6p association with UC.

Mucosal T-cell immunoregulation varies in early and late inflammatory bowel disease.

BACKGROUND AND AIMS: Crohn's disease is a life-long form of inflammatory bowel disease (IBD) mediated by mucosal immune abnormalities. Understanding of the pathogenesis is limited because it is based on data from adults with chronic Crohn's disease. We investigated mucosal T-cell immunoregulatory events in children with early Crohn's disease. METHODS: Mucosal biopsies and T-cell clones were derived from children experiencing the first attack of Crohn's disease, children with long-standing Crohn's disease, infectious colitis, and children without gut inflammation. RESULTS: As in acute infectious colitis, interleukin (IL) 12 induced T cells from early Crohn's disease to acquire a strongly polarised T helper (Th) type 1 response characterised by high IFN-gamma production and IL12Rbeta2 chain expression. Th1 polarisation was not induced in clones from late Crohn's disease. Mucosal levels of IL12p40 and IL12Rbeta2 messenger RNA were significantly higher in children with early than late Crohn's disease. These results demonstrate that susceptibility to IL12-mediated modulation is strongly dependent on the stage of Crohn's disease. CONCLUSIONS: At the onset of Crohn's disease mucosal T cells appear to mount a typical Th1 response that resembles an acute infectious process, and is lost with progression to late Crohn's disease. This suggests that mucosal T-cell immunoregulation varies with the course of human IBD. Patients with the initial manifestations of IBD may represent an ideal population in which immunomodulation may have optimal therapeutic efficacy.

Critical role of the CD40 CD40-ligand pathway in regulating mucosal inflammation-driven angiogenesis in inflammatory bowel disease.

BACKGROUND AND AIMS: Angiogenesis is a novel component in inflammatory bowel disease (IBD) pathogenesis. We have previously shown that immune-nonimmune interactions through the CD40-CD40-ligand (CD40L) pathway might sustain gut inflammation, although their effect on regulating inflammation-driven angiogenesis is unknown. The present study evaluated the role of the CD40-CD40L interaction in the promotion of immune-mediated angiogenesis in IBD. METHODS: Human nonimmune cells of colonic origin-namely, human intestinal fibroblasts (HIFs) and human intestinal microvascular endothelial cells (HIMECs)-were activated with either soluble CD40L (sCD40L), or CD40(+) D1.1 cells or CD40L-activated lamina propria T (LPT) cells before measuring pro-angiogenic cytokine release. Blocking antibodies to either CD40 or CD40L were used to disrupt the CD40-CD40L interaction. The dextran sodium sulphate (DSS) model of experimental colitis in CD40 and CD40L knockout mice was established to assess whether the CD40-CD40L pathway was implicated in controlling inflammation-driven angiogenesis in vivo. RESULTS: Engagement of CD40 on HIFs promoted the release of vascular endothelial growth factor (VEGF), interleukin-8 (IL-8) and hepatocyte growth factor (HGF). LPT cells were potent inducers of pro-angiogenic cytokine secretion by HIFs. Supernatants from sCD40L-activated HIFs induced migration of HIMECs and tubule formation, both of which were inhibited by blocking antibodies to either VEGF, IL-8 or HGF. Both CD40- and CD40L-deficient mice were protected from DSS-induced colitis and displayed a significant impairment of gut inflammation-driven angiogenesis, as assessed by microvascular density. CONCLUSIONS: The CD40-CD40L pathway appears to be crucially involved in regulating inflammation-driven angiogenesis, suggesting that strategies aimed at blocking CD40-CD40L interactions might be beneficial in acute and chronic intestinal injury.

Divergent cell cycle kinetics underlie the distinct functional capacity of mucosal T cells in Crohn's disease and ulcerative colitis.

BACKGROUND: Different abnormalities of T cell effector function distinguish Crohn's disease (CD) from ulcerative colitis (UC). Because cell cycling determines effector function, pathogenic events in CD and UC may depend on cell cycle changes unique to each condition. METHODS: Cell cycle kinetics, cycle regulatory molecule expression, apoptosis, caspase and telomerase activity, and cellular expansion were evaluated in CD2 and CD3 activated control, CD, and UC lamina propria T cells. RESULTS: Compared with normal cells, CD T cells cycle faster, express increased phosphorylated Rb and decreased phosphorylated p53 levels, display less caspase activity but more telomerase activity, die less, and undergo vigorous cellular expansion. In contrast, UC T cells cycle slower, express normal levels of phosphorylated Rb and p53, display more caspase activity but have no telomerase activity, die more, and have a limited capacity to expand. CONCLUSIONS: T cell cycle abnormalities in CD indicate a state of hyperreactivity compatible with loss of tolerance, but a hyporeactive state compatible with anergy in UC. Thus distinct and divergent T cell cycle characteristics underlie the pathogenesis of the two main forms of inflammatory bowel disease.

Activated platelets are the source of elevated levels of soluble CD40 ligand in the circulation of inflammatory bowel disease patients.

BACKGROUND: The CD40/CD40L system, a key regulator and amplifier of immune reactivity, is activated in inflammatory bowel disease (IBD) mucosa. AIMS: To determine whether plasma levels of sCD40L are elevated in Crohn's disease (CD) and ulcerative colitis (UC) patients compared with normal controls, to investigate the cellular source of sCD40L, and to explore CD40L induction mechanisms. PATIENTS: CD, UC, and normal control subjects were studied. METHODS: The concentration of sCD40L in plasma and supernatants of freshly isolated platelets and autologous peripheral blood T cells (PBT) was measured by ELISA. Surface CD40L expression level was measured by flow cytometry in resting and thrombin activated platelets, and unstimulated and CD3/CD28 stimulated PBT before and after coculture with human intestinal microvascular endothelial cells (HIMEC). RESULTS: Compared with normal controls, plasma sCD40L levels were significantly higher in both CD and UC patients and proportional to the extent of mucosal inflammation. Platelets from IBD patients displayed a significantly higher surface CD40L expression than those from control subjects, and released greater amounts of sCD40L than autologous PBT. Contact with IL-1beta activated HIMEC induced significant upregulation of CD40L surface expression and release by platelets. CONCLUSIONS: Elevated levels of sCD40L in the circulation of IBD patients reflect enhanced surface expression and release of CD40L by platelets. This phenomenon translates to an increased platelet activation state apparently induced by passage through an inflamed mucosal microvascular bed, a conclusion supported by the positive correlation of plasma sCD40L levels with the extent of anatomical involvement by IBD. These results suggest that platelet-endothelial interactions critically contribute to activation of the CD40 pathway in IBD.

Inflammatory bowel disease: dogmas and heresies.

Perception of a disease state by the practising physician is based on how easily the diagnosis can be made and how predictable the outcome of the chosen therapy is. The academic investigator perceives the same disease based on how well its cause and mechanism are understood, and how rational pathophysiology-based treatments are. Because of incomplete knowledge, neither the practising physician nor the academic investigator are comfortable in dealing with inflammatory bowel disease, and both seek help in the dogmas and heresies inevitably associated with chronic disease of unknown aetiology.

Inflammatory bowel disease. Current concepts of pathogenesis and implications for therapy.

Inflammatory bowel disease (IBD) still presents major challenges to the understanding of its cause, mechanisms of inflammation, and therapeutic choices to control the damaged tissue. Both types of IBD, ulcerative colitis and Crohn's disease, have been known and investigated for over half century but neither one is fully understood nor can be satisfactorily managed. While many gaps in our knowledge still exist, the last two decades have witnessed an unprecedented progress not only in the etiology but mainly in the mechanisms underlying the chronic inflammatory response. The pattern of IBD epidemiology has drastically changed since World War II, with an increased frequency in countries that have adopted a ''westernized'' life style. A parallel and important phenomenon is the continuous drop in age of onset in children. Unfortunately, only few epidemiological clues are available, with the exception of smoking and diet. What in smoking alters the course of IBD is still a mystery and which, among thousands of additives, could represent a risk factor will remain unknown for the foreseeable future. The current emphasis on the study of the enteric flora as the source of potential antigens against which the mucosal immune system reacts appear well justified. The data from animal models appears particularly convincing. Thus, after decades of relying almost exclusively on patient-derived information, numerous animal models are generating precious new information on IBD pathogenesis. In experimental IBD the genetic background of the animal markedly influences the course of the disease, and the same is probably true in humans. The identification of NOD2 as the first mutated gene associated with a subgroup of Crohn's disease patients is the first evidence that genetics are pointing to the right direction for understanding how the environment interacts with genes to cause IBD. For many years immunology has been the main source of scientific information on mechanisms of IBD. Cytokines, chemokines and other soluble factors dominate immunological studies aimed at understanding how different anti-inflammatory and pro-inflammatory mediators are improperly regulated and how immune imbalance can be restored. The extent to which T-cells live or die is also a key determinant of chronicity. In addition to classical immune cells, epithelial, endothelial, mesenchymal and nerve cells are slowly gaining more importance in IBD pathogenesis, as they contribute to the ultimate fate of tissue damage. Medical and surgical therapies are vastly better now that they were only a couple of decades ago, but they are still far from satisfactory. Steroid and aminosalicylates are still the most common drugs after 60 years of use, and it is time to renovate our therapeutic approach to a more effective one. The value of biologicals has been highlighted by the recent success of anti-TNF therapy. Timing of therapy must also change. The concept of the step-by-step approach is slowly fading away, and the idea of an ''all-out'' approach with multiple concomitant drugs early in the disease is gaining credibility. New reports on early aggressive therapies, and the demonstration that early and late experimental IBD are caused by different mechanisms are changing the way we think about managing IBD. Both ulcerative colitis and Crohn's disease will continue to challenge the medical establishment for year to come, but the possibility that IBD can be conquered is more realistic now that never before.

Decreased Bax expression by mucosal T cells favours resistance to apoptosis in Crohn's disease.

BACKGROUND: Activated T cells are more susceptible to apoptosis than resting T cells. As intestinal T cells normally exhibit a higher state of activation, increased apoptosis may be necessary to maintain immune homeostasis in the specialised microenvironment of the mucosa. On the other hand, in Crohn's disease (CD) mucosal T cells are resistant to apoptosis, suggesting abnormal regulation of cell death mechanisms. AIMS: To investigate differences in expression of anti- and proapoptotic Bcl-2 family proteins, key regulators of apoptosis, between circulating and mucosal T cells, and possible alterations in CD. PATIENTS AND METHODS: Lamina propria T cells (LPT) were isolated from 10 control, seven CD, and eight ulcerative colitis (UC) patients, and peripheral blood T cells (PBT) from healthy volunteers. Purified T cells were stained intracellularly for Bcl-2, Bcl-x(L), and Bax, and mean fluorescence intensity measured by flow cytometry. RESULTS: Compared with PBT, the expression level of Bcl-2 and Bax, but not Bcl-x(L), was significantly greater in LPT, resulting in lower Bcl-x(L)/Bax ratios. In PBT, Bax expression was highly and significantly correlated with both Bcl-2 and Bcl-x(L), but correlation with Bcl-2 was absent in LPT. Bax expression in CD, but not UC, LPT was significantly lower than in control LPT, resulting in a significantly higher Bcl-x(L)/Bax ratio. The significant correlation of Bcl-x(L) to Bax was preserved in CD, but not UC, LPT. CONCLUSIONS: Regulation of Bcl-2 family protein expression differs between circulating and mucosal T cells, probably underlying diverse survival potentials. In CD LPT, a low Bax expression and a high Bcl-x(L)/Bax ratio favour resistance to apoptosis and may contribute to the chronicity of inflammation.

Regulation of life and death in lamina propria T cells.

T cells are essential to initiation, amplification, and regulation of an immune response. This response is terminated when T cells undergo apoptosis, a physiological process of cell death triggered by various mechanisms and regulated by signaling pathways leading to enzymatic degradation of chromatin. An effective immune response depends on the proper balance between proliferation and death of activated T cells. This is particularly important in the intestine, where mucosal T cells are subjected to the high antigenic pressure of lumenal antigens and apoptosis is required to induce tolerance and maintain a state of 'physiological' inflammation. Insufficient apoptosis may result in excessive T cell retention and chronic intestinal inflammation, as seen in conditions associated with defective apoptosis of lamina propria T cells.

Pharmacokinetic evaluation of oral levofloxacin in human immunodeficiency virus-infected subjects receiving concomitant antiretroviral therapy.

The purpose of this study was to evaluate the pharmacokinetics (PK) profile of oral levofloxacin in human immunodeficiency virus-positive patients in steady-state treatment with nelfinavir (NFV) or with efavirenz (EFV) and to determine the effects of levofloxacin on the PK parameters of these two antiretroviral agents. For levofloxacin, plasma samples were obtained at steady state during a 24-h dosing interval. Plasma NFV and EFV concentrations were evaluated before and after 4 days of levofloxacin treatment. Levofloxacin PK do not seem affected by NFV and EFV. There was no significant difference between NFV and EFV plasma levels obtained with and without levofloxacin.

Hierarchical cleavage of focal adhesion kinase by caspases alters signal transduction during apoptosis of intestinal epithelial cells.

BACKGROUND & AIMS: Purified intestinal epithelial cells die of detachment-induced apoptosis due to loss of cell anchorage during isolation. Anchorage-dependent cells form focal adhesions, sites of enhanced cell-matrix attachment that confer survival signals. Focal adhesion kinase (FAK), a component of the focal adhesion signaling complex, transduces these antiapoptotic signals. In this report, the molecular events leading to cleavage of FAK by caspases during apoptosis and its functional implications are defined. METHODS: Cytosolic extracts of human intestinal epithelial cells undergoing detachment-induced apoptosis were analyzed by Western blotting, immunoprecipitation, and kinase assay. RESULTS: FAK is cleaved by the ordered proteolytic activity of 2 different members of the caspase-3 family. The first cleavage is mediated by caspase-3, generating a 94/92-kilodalton-terminal fragment, which is processed by caspase-6 to an 84-kilodalton fragment. After apoptosis is initiated, the level of FAK phosphorylation is rapidly decreased, and the phosphorylation pattern of FAK-associated proteins is dramatically modified, showing significant yet divergent changes in signal transduction. CONCLUSIONS: Cleavage of FAK during apoptosis of normal human cells is an example of the sequential, highly regulated, and coordinate action of caspases that not only dismantle a cell by proteolysis, but also alter the cell's signaling machinery.

Ulcerative colitis and Crohn's disease: distinctive gene expression profiles and novel susceptibility candidate genes.

To elucidate the biological dysregulation underlying two forms of inflammatory bowel disease (IBD), ulcerative colitis (UC) and Crohn's disease (CD), we examined global gene expression profiles of inflamed colonic tissue using DNA microarrays. Our results identified several genes with altered expression not previously linked to IBD. In addition to the expected upregulation of various cytokine and chemokine genes, novel immune function-related genes such as IGHG3, IGLL2 and CD74, inflammation-related lipocalins HNL and NGAL, and proliferation-related GRO genes were over-expressed in UC. Certain cancer-related genes such as DD96, DRAL and MXI1 were differentially expressed only in UC. Other genes over-expressed in both UC and CD included the REG gene family and the calcium-binding S100 protein genes S100A9 and S100P. The natural antimicrobial defensin DEFA5 and DEFA6 genes were particularly over-expressed in CD. Overall, significant differences in the expression profiles of 170 genes identified UC and CD as distinct molecular entities. The genomic map locations of the dysregulated genes may identify novel candidates for UC and CD genetic susceptibility.

Selective resistance of mucosal T-cell activation to immunosuppression in Crohn's disease.

BACKGROUND & AIMS: The inappropriately high state of T-cell activation found in Crohn's disease could be due to failure to respond to inhibitory signals. We tested the hypothesis that Crohn's disease mucosal T-cells are resistant to the immunosuppressive action of interleukin4. PATIENTS: Patients with Crohn's disease, ulcerative colitis, and other malignant and non-malignant conditions undergoing bowel resection. METHODS: The effect of interleukin-4 on lamina propria mononuclear cells from Crohn's disease, ulcerative colitis and control mucosa was assessed on various T-cell functions: interleukin-2-induced cytotoxicity, soluble interleukin-2 receptor and interleukin-2 production, and expression of mRNA for interleukin-2R and interferon-gamma. RESULTS: Cytotoxicity of control and ulcerative colitis cells was markedly decreased by interleukin-4, whereas Crohn's disease cells failed to be inhibited. Addition of interleukin-4 to interleukin-2-stimulated cultures decreased soluble interleukin-2R production significantly less in Crohn's disease and ulcerative colitis than control cells. In the same cultures, residual levels of interleukin-2 were significantly increased in control and ulcerative colitis, but not Crohn's disease cultures. Finally, Crohn's disease cells were significantly more resistant to interleukin-4-mediated inhibition of spontaneous and interleukin-2-induced expression of interleukin-2Ralpha and interferon-gamma mRNA compared to control cells. CONCLUSIONS: The effector function, receptor expression and cytokine production of Crohn's disease mucosal T-cells are resistant to interleukin4-mediated inhibition. Failure to respond to down-regulatory signals may contribute to persistent T-cell activation and chronicity of inflammation in Crohn's disease.