Search

Background: We and others have reported the prophylactic efficacy of oral consumption of probiotic lactobacilli in the interleukin 10 knockout (IL-10 KO) model of colitis. It has not been demonstrated that the oral route is essential for probiotic efficacy., Aims: (i) To determine the effect of parenteral administration (subcutaneous) of Lactobacillus salivarius 118 on colitis of IL-10 KO mice; and (ii) to determine if observed responses are disease specific., Methods: (i) IL-10 KO mice were injected subcutaneously with L salivarius 118 or saline over 19 weeks. At sacrifice, the bowels were histologically scored. Isolated splenocytes were cultured in vitro and cytokine levels measured. (ii) In the collagen induced arthritis model, DBA/1 mice were injected subcutaneously with the probiotic or saline. At sacrifice, paw thickness was measured and joints were histologically scored., Results: (i) Colonic inflammatory scores were significantly decreased in IL-10 KO mice injected with L salivarius 118 compared with controls (p<0.05). Proinflammatory cytokine production from stimulated splenocytes was significantly lower for the probiotic group whereas stimulated transforming growth factor beta (TGF-beta) levels were significantly increased (p<0.05). (ii) Scoring of arthritis and paw thickness were significantly improved in the group of mice injected with L salivarius 118 compared with controls., Conclusions: (1) Subcutaneous administration of L salivarius 118 significantly attenuated colitis in the IL-10 KO model and suppressed collagen induced arthritis, suggesting that the oral route may not be essential for probiotic anti-inflammatory effects and that responses are not disease specific. (2) The probiotic effect was associated with reduced production of proinflammatory (T helper 1) cytokines and maintained production of anti-TGF-beta.

Background: Prophylactic efficacy against colitis following lactobacillus consumption in interleukin 10 (IL-10) knockout (KO) mice has been reported. Whether this applies equally to other probiotic strains is unknown, and the mechanism is unclear., Aims: (1) To compare the effect of feeding Lactobacillus salivarius subspecies salivarius 433118 and Bifidobacterium infantis 35624 against placebo on enterocolitis, the intestinal microflora, and (2) to compare the systemic immunological response to in vitro microbial challenge in probiotic fed and control IL-10 KO mice., Methods: Three groups of 10 IL-10 KO mice were fed fermented milk products containing Lb salivarius 433118 at 10(9) CFU/ml, B infantis 35624 at 10(8) CFU/ml, and unmodified milk, respectively, for 19 weeks. Faecal samples were taken at regular intervals to confirm gut transit, recovery of fed probiotics, and to assess the impact on the microflora. At sacrifice, the bowels were histologically scored. Cytokine production from Peyers' patches and splenocytes was measured in vitro by ELISA., Results: Faecal recovery of probiotics was confirmed in all probiotic fed mice but not in controls. Colonic and caecal inflammatory scores were significantly decreased in both groups of probiotic fed mice (p<0.05). Proinflammatory cytokine production by Peyers' patches and splenocytes was significantly reduced in probiotic fed animals whereas transforming growth factor beta (TGF-beta) levels were maintained., Conclusion: Both Lactobacillus salivarius 433118 and Bifidobacterium infantis 35624 significantly attenuate colitis in this murine model. Attenuation of colitis is associated with a reduced ability to produce Th1-type cytokines systemically and mucosally, while levels of TGF-beta are maintained.

Background and Aims: The uncertainty surrounding the role of Mycobacterium avium subsp paratuberculosis (Map) in Crohn's disease has been compounded by possible contamination from Map present in the lumen microflora. This study used laser capture microdissection (LCM) and polymerase chain reaction (PCR) to detect Map DNA in subepithelial granulomas, isolated from 15 surgically resected, formalin fixed specimens of granulomatous Crohn's disease and from 12 granulomatous disease controls (10 bowel, 2 non-bowel)., Methods: The effect of amplicon size on reliability of PCR from formalin fixed samples was examined by amplifying 435 bp and 133 bp sequences of the human APC gene. After this, nested primers were designed to detect a small fragment (155 bp) of the Map specific IS900 gene in Crohn's granulomas. LCM isolated granulomas from Map culture positive bovine intestine was used as positive control. PCR product specificity was confirmed by direct DNA sequencing., Results: The smaller, but not the larger, fragment of the APC gene amplified reliably in all samples. Amplification of the 155 bp fragment of the IS900 gene detected Map DNA in microdissected Crohn's granulomas in 6 of 15 cases, and in 0 of 12 disease control granulomas., Conclusions: LCM can be used to detect Map DNA in granulomas in a proportion of patients with Crohn's disease. However, formalin fixation requires that comparatively short DNA fragments of the Map specific IS900 gene be targeted, to permit consistent detection. Detection of Map DNA within granulomas might suggest an infectious aetiology in a subset of patients; alternatively, a transmissible agent may not be involved but mycobacterial DNA may influence pathogenesis by modifying the local cytokine responses.

Background: Substantial evidence implicates the neuropeptide substance P (SP) in mucosal immunoinflammatory responses. Autoradiographic studies have suggested a disturbance in SP receptor expression in inflammatory bowel disease (IBD)., Aims: Because of technical limitations such as poor cellular resolution with autoradiography, we used molecular methods to specifically localise the cellular expression of the neurokinin-1 receptor (NK-1R) in IBD colon, and to quantitate NK-1R mRNA expression levels therein., Methods: In situ hybridisation and immunohistochemistry were used to localise NK-1R mRNA and protein, respectively, in normal, ulcerative colitis (UC), and Crohn's disease (CD) colonic resections. NK-1R mRNA expression levels of normal, UC, and CD mucosal biopsies were quantitated by competitive reverse transcription-polymerase chain reaction., Results: NK-1R expression was localised to lamina propria mononuclear cells, epithelium, submucosal vasculature, smooth muscle, and myenteric plexus of normal and IBD colon. No ectopic NK-1R expression was observed in IBD. However, we found increased numbers of NK-1R expressing lymphoid cells in IBD tissue, aberrant negative epithelial expression of NK-1R in UC, and increased expression of NK-1R in CD myenteric plexus. Quantitation of NK-1R mRNA expression in IBD colonic mucosal biopsies revealed marked upregulation of NK-1R mRNA levels compared with non-inflamed mucosal expression levels (p<0.01)., Conclusions: This report demonstrates the strategic localisation and upregulation of NK-1R expression in IBD colon, and thereby suggests the involvement of substance P in the pathophysiological symptoms of IBD.

Background: Despite being immunogenic, gastric cancers overcome antitumour immune responses by mechanisms that have yet to be fully elucidated. Fas ligand (FasL) is a molecule that induces Fas receptor mediated apoptosis of activated immunocytes, thereby mediating normal immune downregulatory roles including immune response termination, tolerance acquisition, and immune privilege. Colon cancer cell lines have previously been shown to express FasL and kill lymphoid cells by Fas mediated apoptosis in vitro. Many diverse tumours have since been found to express FasL suggesting that a "Fas counterattack" against antitumour immune effector cells may contribute to tumour immune escape., Aim: To ascertain if human gastric tumours express FasL in vivo, as a potential mediator of immune escape in stomach cancer., Specimens: Thirty paraffin wax embedded human gastric adenocarcinomas., Methods: FasL protein was detected in gastric tumours using immunohistochemistry; FasL mRNA was detected in the tumours using in situ hybridisation. Cell death was detected in situ in tumour infiltrating lymphocytes using terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL)., Results: Prevalent expression of FasL was detected in all 30 resected gastric adenocarcinomas examined. In the tumours, FasL protein and mRNA were co-localised to neoplastic gastric epithelial cells, confirming expression by the tumour cells. FasL expression was independent of tumour stage, suggesting that it may be expressed throughout gastric cancer progression. TUNEL staining disclosed a high level of cell death among lymphocytes infiltrating FasL positive areas of tumour., Conclusions: Human gastric adenocarcinomas express the immune downregulatory molecule, FasL. The results suggest that FasL is a prevalent mediator of immune privilege in stomach cancer.

Background: The bacterial chemotactic peptide N-formyl-methionine-leucine-phenylalanine (FMLP) is produced by enteric flora and is one of the factors implicated in contributing to inflammatory bowel disease. Expression of receptors for FMLP on human phagocytes (polymorphs and monocytes) is well established, but there is conflicting evidence regarding the potential expression of FMLP receptors on other cells within the mucosa, particularly the epithelial cells., Aims: To map FMLP receptors within intestinal mucosa using several different experimental approaches., Methods and Results: Radioligand binding assays with 'H-FMLP' revealed no specific binding to primary cultured colonic enterocytes or to the cell line HT29, whereas neutrophils, as expected, exhibited specific binding with a Kd of 19 nM and approximately 2 x 10(4) receptors per cell. FITC labelled FMLP exhibited specific, displaceable binding on flow cytometry to neutrophils and monocytes but not to 10 gastrointestinal epithelial cell lines. Isolated lamina propria lymphocytes and peripheral blood lymphocytes exhibited no binding. To confirm the absence of receptors on epithelia, reverse transcription polymerase chain reaction for mRNA for the classic FMLP receptor was performed. While the presence of message was detected in activated peripheral blood phagocytes, it was not detected in epithelial cell lines. To exclude the possibility of FMLP binding to other receptors such as tachykinin receptors on epithelia, FITC labelled FMLP binding in tissue sections confirmed that the binding is subepithelial--that is, in the lamina propria., Conclusion: Receptors for FMLP are subepithelial and map to the lamina propria of the gastrointestinal mucosa.

Background: Micrometastases within bone marrow have been shown to indicate a poor prognosis in patients with epithelial tumours. However, the degree to which micrometastases represent true residual disease or cell shedding and metastatic potential, is unclear., Aim: To explore whether micrometastases represent residual disease, bone marrow taken from carefully staged patients before and after (> 6 months) "curative" resection of a primary gastrointestinal cancer was studied prospectively., Patients/methods: Seventy two consecutive patients were studied; the only exclusions were patients with known overt metastatic disease at the time of surgery. Micrometastatic cells were quantified per 10(5) marrow cells by flow cytometry after staining for contaminant cytokeratin-18 positive cells., Results: Micrometastases were detected preoperatively in 22% (16/72) of all patients, comprising 11 (23%) of 48 with colorectal cancer, five (33%) of 15 with gastric adenocarcinoma and none (0%) of nine with oesophageal squamous cancer. Although fewer metastatic cells were detected in postoperative bone marrow, and clearance of marrow deposits was evident in most patients, the persistence of micrometastases in five of 16 patients after resection, without evidence of tumour recurrence, indicates a subset with true residual disease. Detection of micrometastases postoperatively (persistent or newly developed) was significantly associated with development of overt metastases during the subsequent 12-18 months of follow up (nine of 19 patients) when compared with patients testing negative for micrometastases (eight of 53; p < 0.01)., Conclusions: Preoperative detection of micrometastases may reflect either transient shedding of cells, metastatic potential or residual disease, but postoperative micrometastases indicate minimal residual disease. Identification of these patients is important because they may benefit from adjuvant therapy.