Spondyloarthropathy and Idiopathic Inflammatory Bowel Diseases

The bacterial flora in inflammatory bowel disease: current insights in pathogenesis and the influence of antibiotics and probiotics

The pathogenesis of inflammatory bowel disease (IBD) remains unknown, although in recent years more data have become available. The contribution of genetic and environmental factors is evident, and the luminal bacterial flora plays a major role in the initiation and perpetuation of chronic IBD. Animal models of IBD have shown that colitis does not occur in a germ-free environment. In human IBD, inflammation is present in parts of the gut containing the highest bacterial concentrations. Moreover, the terminal ileum, caecum and rectum are areas of relative stasis, providing prolonged mucosal contact with luminal contents. Enhanced mucosal permeability may play a pivotal role in maintaining a chronic inflammatory state, due to a genetic predisposition or as a result of direct contact with bacteria or their products. A detective epithelial barrier may cause a loss of tolerance to the normal enteric flora. Furthermore, an increased mucosal absorption of viable bacteria and bacterial products is found in IBD. Serum and secreted antibodies are increased and mucosal T-lymphocytes that recognize luminal bacteria are present. However, there is evidence that the immune system reacts over aggressively towards the normal luminal flora rather than the flora being altered in IBD. Several approaches have been used in attempts to discover a specific microbial agent in the cause of IBD. These include demonstration of the presence of organisms or specific antigens in affected tissues, culture of microbes firm the affected tissues, demonstration of serological responses to several agents, and localization and detection of individual pathogen-specific nucleic acid sequences in affected tissue by in situ hybridization and polymerase chain reaction. So far, no specific micro-organism has been directly associated with the pathogenesis of IBD. Analysis of the luminal enteric flora, however, has revealed differences in the composition of this flora compared to healthy controls. In Crohn disease, concentrations of Bacteroides, Eubacteria and Peptostreptococcus are increased, whereas Bifidobacteria numbers are significantly reduced. Furthermore, in ulcerative colitis, concentrations of facultative anaerobic bacteria are increased. The arrival of new molecular techniques qualifying and quantifying the complex intestinal flora has induced a revival of interest in this microflora. Therapeutic approaches geared towards changing the environment at the mucosal border have been attempted by the use of elemental diets, total parenteral nutrition, surgical diversion of the faecal stream and antibiotics. Over the past few years, the use of probiotics in IBD and other intestinal disorders has gained attention. Strengthened by promising experimental data and commercial interests, research in this field is rapidly expanding. Manipulation of the colonic bacteria with antibiotic drugs and probiotic agents may prove to be more effective and better tolerated than immunosuppressants in the future.

Diagnosing the systemic associations of anterior uveitis

Up to one-half of patients with anterior uveitis suffer from related systemic diseases. The common associations are the seronegative arthropathies and, in children, juvenile chronic arthritis. Anterior uveitis may also occur in the context of sarcoidosis or Behçet's disease. Syphilis and tuberculosis remain a significant problem for specific populations and may be the cause of anterior uveitis in these groups. By thorough clinical history and the correct selection and interpretation of simple investigations, it is generally possible for the ophthalmologist to make or exclude a systemic diagnosis, predict the ocular prognosis and direct selected patients to the appropriate physician. Diseases that threaten the patient's wellbeing must certainly be recognized. In the present review we present a method for identifying the systemic associations of anterior uveitis.

Review article: Role of the enteric microflora in the pathogenesis of intestinal inflammation and arthritis

Strong associations exist between intestinal inflammation and arthritis, ranging from infections with enteric pathogens to idiopathic inflammatory bowel disease. Increased exposure of the lamina propia and systemic circulation to enteric microflora and their products are a result of increased proliferation of the luminal bacteria, pathogenic invasion or enhanced mucosal permeability. Data suggest that anaerobic bacteria and other constituents of the normal luminal microbial flora induce and sustain chronic intestinal inflammation and arthritis. However, the normal host develops a tolerance to such bacteria and maintains homeostasis through a controlled inflammatory response and an almost impermeable mucosal barrier.