Functional interactions between mucosal IL-1, IL-ra and TGF-beta 1 in ulcerative colitis.

OBJECTIVE: Studies aiming to define key cytokines in inflammatory bowel disease have been restricted to gene expression or protein quantitation but lack functional information on cytokine interactions. Some of the major cytokines that govern the extent and duration of the inflammatory process in ulcerative colitis (UC), appear to be interleukin 1 (IL-1), its natural inhibitor IL-1 receptor antagonist (IL-1ra) and transforming growth factor beta1 (TGF-beta 1). Indeed, as a predictor of inflammation, the mucosal status of IL-1, depicted as a ratio of IL-1ra/IL-1, has often been used. METHODS: Using an IL-1 bioassay and specific anti-cytokine antibodies we have identified the functional role of these cytokines and their interactions in mucosal biopsy samples taken from patients with UC. RESULTS: Compared with control specimens, the secreted and tissue levels of IL-1 were consistently raised in UC samples. Levels of IL-1, rather than IL-1ra or the ratio of IL-1ra/IL-1, most closely mirrored the severity of inflammation. Using specific antibodies we showed that IL-1ra and TGF-beta 1 appear to modulate the degree of inflammation at different stages of the inflammatory process. Only in severely inflamed tissue, when IL-1 levels were high did IL-1ra inhibit IL-1-induced activity. In contrast, the levels of TGF-beta 1, and its effect in controlling inflammation, was most marked in mild but not severe UC. CONCLUSIONS: The functional roles of these cytokines in the inflammatory process can now be more carefully elucidated using a bioassay and specific neutralising antibodies.

Competition between IL-1, IL-1ra and TGF-beta 1 modulates the response of the ELA4.NOB-1/CTLL bioassay: implications for clinical investigations.

OBJECTIVE: The use of ELISA techniques to measure cytokine levels in clinical samples has chiefly replaced more labour intensive bioassays. ELISA measurements, however, do not reflect the functional activity of a cytokine within a sample; interleukin-1 (IL-1), for example, has two agonist isoforms (IL-1 alpha and IL-1 beta) and a competitive receptor antagonist (IL-1ra), and can be regulated by transforming growth factor beta1 (TGF-beta 1). The net effect of these cytokines, rather than IL-1 levels, are frequently suggested to regulate tissue inflammation, but confirming this has been difficult. METHODS: We used the ELA4.NOB-1/CTLL co-culture IL-1 bioassay to investigate whether IL-1 activity was inhibited by IL-1ra and TGF-beta 1 in a predictable manner. RESULTS: Thymidine incorporation into CTLL cells, induced by IL-1, was reduced dose dependently by IL-1ra and TGF-beta 1. With optimal levels of IL-1 CTLL responsiveness was reduced by 90% by 1 ng/ml TGF-beta 1 and completely abolished by 100 ng/ml IL-1ra. As expected, TGF-beta 1 and IL-1ra had independent mechanisms of action on the bioassay cell lines, and, in combination, they caused an additive, but not synergistic, effect. Importantly, the effect of these cytokines could be completely abolished in the presence of neutralising antibodies. CONCLUSIONS: Bioassay should provide specific functional information on the net IL-1 activity of clinical samples, while the use of specific antibodies could ascertain the contribution of individual cytokines within such samples.

Historical and current perspectives on bone marrow transplantation for prevention and treatment of immunodeficiencies and autoimmunities.

Primary immunodeficiency diseases often fully meet the definition of "experiments of nature." Much of the expanding understanding of the lymphoid systems and immunologic functions generated in recent years has been derived from studying patients with primary, generally genetically determined immunodeficiency diseases, as well as other relatively rare secondary immunodeficiency diseases. Increasing knowledge of immunologic defenses, their interacting cellular and molecular components, the evolving details of sequential stages of cellular differentiation, and the nature and control of the cellular and molecular interactions in immunity have now made it possible to define precisely many primary immunodeficiency diseases in full molecular genetic terms. With this wealth of scientific information based on experimental and clinical research, incredible advances have also been made in using bone marrow transplantation (BMT) often as a curative treatment for immunodeficiency, some 60 to 70 other diseases, leukemias, lymphomas, other cancers, and a rapidly expanding constellation of metabolic diseases or enzyme deficiencies. Also, progress in applying allogeneic BMT to prevent, treat, and cure complex autoimmune diseases, primary immunodeficiency diseases and certain forms of cancers, is considered. Further, mixed BMT (syngeneic plus allogeneic) that establishes a form of stable mixed chimerism has also been employed in animal experiments, which revealed that BMT can be used to treat not only immunodeficiency diseases, but also systemic and organ-specific autoimmune diseases, eg, diabetes and erythematous lupus-like diseases. Moreover, performing BMT in conjunction with organ allografts, eg, thymus or pancreatic transplants, has successfully prevented rejection of these allografts, sometimes without recourse to long-term irradiation or toxic chemical immunosuppressive agents. A crucial role for stromal cells in cellular engineering has now also been realized in animal models as a means of preventing graft rejection and promoting full and persistent reconstitution or correction of genetically-based diseases. With all of these achievements, BMT promises continued dramatic and impressive new approaches to clinical and scientific research and reveals an attractive strategy for the treatment and prevention of many currently intractable human diseases. If these achievements can be extended to larger outbred animals and humans, BMT may set the stage for induction of improved immunologic tolerance and for developing treatments for additional intractable human diseases in the 21st century.