Thomas A. Judge

Extraintestinal manifestations of inflammatory bowel disease

Numerous extraintestinal diseases have been associated with IBD. The role of the gastrointestinal tract in host response to the foreign antigens present in the gut makes the enteric immune system highly susceptible to any external perturbation to the system. Dysregulation of the enteric immune response results in pathology in various organs outside of the gut. The site-specific manifestations of this immune response are not understood fully. Better understanding of the pathogenesis of IBD and the complex interactions between the gut immune system and the extraintestinal systems would provide insights into the development of many of these extraintestinal manifestations. Much is unknown about the presence of cardiac, pulmonary, and hematologic diseases in patients with IBD. True association or coincidental presence of the diseases in these organ systems with IBD requires better delineation. An important consideration in all patients with IBD presenting with extraintestinal manifestations should be a careful search for medication-related complications.

Amelioration of collagen-induced arthritis by CD95 (Apo-1/Fas)-ligand gene transfer.

Both rheumatoid arthritis and animal models of autoimmune arthritis are characterized by hyperactivation of synovial cells and hyperplasia of the synovial membrane. The activated synovial cells produce inflammatory cytokines and degradative enzymes that lead to destruction of cartilage and bones. Effective treatment of arthritis may require elimination of most or all activated synovial cells. The death factor Fas/Apo-1 and its ligand (FasL) play pivotal roles in maintaining self-tolerance and immune privilege. Fas is expressed constitutively in most tissues, and is dramatically upregulated at the site of inflammation. In both rheumatoid arthritis and animal models of autoimmune arthritis, high levels of Fas are expressed on activated synovial cells and infiltrating leukocytes in the inflamed joints. Unlike Fas, however, the levels of FasL expressed in the arthritic joints are extremely low, and most activated synovial cells survive despite high levels of Fas expression. To upregulate FasL expression in the arthritic joints, we have generated a recombinant replication-defective adenovirus carrying FasL gene; injection of the FasL virus into inflamed joints conferred high levels of FasL expression, induced apoptosis of synovial cells, and ameliorated collagen-induced arthritis in DBA/1 mice. The Fas-ligand virus also inhibited production of interferon-gamma by collagen-specific T cells. Coadministration of Fas-immunoglobulin fusion protein with the Fas-ligand virus prevented these effects, demonstrating the specificity of the Fas-ligand virus. Thus, FasL gene transfer at the site of inflammation effectively ameliorates autoimmune disease.

An open-label trial of the PPARγ ligand rosiglitazone for active ulcerative colitis

OBJECTIVES:Previous research has demonstrated that ligands for the γ subtype of peroxisome proliferator-activated receptors (PPARs) reduce inflammation in two different murine models of colitis. This study was designed to examine the potential efficacy of rosiglitazone, a ligand for the γ subtype of PPARs, as a therapy for active ulcerative colitis.METHODS:Fifteen patients with mild to moderately active ulcerative colitis despite therapy with 5-aminosalicylic acid compounds were enrolled in an open-label study of rosiglitazone (4 mg b.i.d. p.o.) for 12 wk. Thirteen of 15 patients were receiving concomitant therapy with corticosteroids and/or immunomodulator medications. Disease activity was measured with the Disease Activity Index.RESULTS:After 12 wk of therapy, four patients (27%) had achieved clinical remission, of whom three (20%) also had an endoscopic remission. Four additional patients (27%) had a clinical response without achieving remission. Two patients were hospitalized with worsened disease activity, and one patient was withdrawn for nephrotic syndrome.CONCLUSIONS:These data suggest that ligands for the γ subtype of PPARs may represent a novel therapy for ulcerative colitis. A double blind, placebo-controlled, randomized trial is warranted.

Adenovirus-mediated gene transfer into cold-preserved liver allografts: Survival pattern and unresponsiveness following transduction with CTLA4Ig

The immune response of liver transplant recipients was modulated via adenovirus-mediated transduction of the cold-preserved liver with sequences encoding CTLA4lg. Transplanted allografts demonstrated rapid transient local expression and recombinant protein production shortly after revascularization, resulting in intact liver function, indefinite survival of the recipient, and the development of donor-specific unresponsiveness. Lymphocytic infiltration of the graft was mainly of the T helper 2 (Th2) subset and was not associated with injury to primary cellular targets of the alloimmune response. These findings demonstrate a successful outcome of a feasible and potentially clinically relevant system of gene delivery of sequences encoding proteins capable of inhibiting the alloimmune response.

Device choice and experience level in endoscopic foreign object retrieval: An in vivo study

BACKGROUND Successful foreign object retrieval may depend on device choice and the experience level of the endoscopist, although these factors have not been systematically evaluated. METHODS In anesthetized pigs, the ability to retrieve foreign objects (metal tack, button disc battery, wooden toothpick) placed endoscopically into the stomach was assessed. Seven university medical center gastroenterology attending physicians (5 clinical and 2 basic science research [BSR]), and 4 fellows-in-training participated. The devices used were the Roth retrieval net, rat tooth forceps, Dormia basket, polypectomy snare, and radial jaw forceps. The time to retrieve each object into an esophageal overtube within a 5 minute maximum was measured. RESULTS Only the Roth net and Dormia basket were successful in retrieving the button disc battery, although the Roth net was superior (100% vs 27%, Fisher p < 0.025). All devices were equally successful at retrieving the tack (82% to 100%, p = NS). The snare was significantly faster than the Roth net (p < 0.05). For the tack, there was significantly fewer difficulties encountered with the snare than the Roth net (Fisher p < 0.03). The Roth net was incapable of retrieving the toothpick; the other devices were equally successful (91% to 100%). The clinical attendings had a significantly higher success rate (95%) than the fellows (82%, chi squared p < 0.05) or combined fellows/BSR attendings (80%, p < 0.02), and were significantly faster than the fellows (p < 0.0002) or the fellows/BSR attendings (p < 0.0003). CONCLUSIONS The Roth net is the best device for retrieving smooth objects such as the button disc battery. For sharp objects, such as the tack and toothpick, best results were achieved with the snare, although the forceps were also effective. More experienced endoscopists had higher success rates and faster retrieval times. Both device choice and the experience level of the endoscopists have an impact on successful foreign object retrieval.

TISSUE-SPECIFIC CONSEQUENCES OF THE ANTI-ADENOVIRAL IMMUNE RESPONSE: IMPLICATIONS FOR CARDIAC TRANSPLANTS

The immune response to adenoviral vectors can induce inflammation and loss of transgene expression in transfected tissues. This would limit the use of adenovirus-mediated gene transfer in disease states in which long-term gene expression is required. While studying the effect of the anti-adenoviral immune response in transplantation, we found that transgene expression persisted in cardiac isografts transfected with an adenovirus encoding β-galactosidase. Transfected grafts remained free of inflammation, despite the presence of an immune response to the vector. Thus, adenovirus-mediated gene transfer may have therapeutic value in cardiac transplantation and heart diseases. Furthermore, immunological limitations of adenoviral vectors for gene therapy are not universal for all tissue types.

Utility of adenoviral-mediated Fas ligand gene transfer to modulate islet allograft survival

BACKGROUND One of the best-defined mechanisms for the induction of apoptosis involves signaling via the cell surface molecule Fas, after binding of Fas ligand. Expression of Fas ligand is tightly regulated, being expressed primarily by T cells after activation, where it serves as a self-regulatory mechanism for immune responses. Fas ligand has also been found to be expressed constitutively at sites of immune privilege such as the testes and the anterior chamber of the eye. Recently, co-transplantation of Fas ligand-transfected myoblasts in association with islet cell allografts was shown to prolong islet allograft survival but only rarely led to indefinite graft survival. Graft rejection was associated with loss of Fas ligand on the myoblasts, suggesting that direct expression of the transgene on the islets might be more effective. METHODS A replication-defective adenoviral construct containing murine Fas ligand (Ad/MFL) was prepared by homologous recombination. NIH 3T3 cells, rodent splenocytes, and murine islets were infected with Ad/MFL and examined in vitro for functional murine Fas ligand expression. Survival of Ad/MFL-infected islets was subsequently evaluated in vivo in both syngeneic and allogeneic islet transplantation models. RESULTS Cell lines and islet allografts transfected with Ad/MFL expressed a functional Fas ligand, capable of inducing apoptosis (confirmed by three distinct assays for DNA fragmentation) in Fas+ targets, but not in Fas- controls. Furthermore, Ad/MFL was able to modify allogeneic immune responses in vitro, as addition of this virus, but not a control adenovirus, significantly reduced proliferation in a mixed lymphocyte reaction. Surprisingly, however, transplantation of islet allografts transfected with Ad/MFL resulted in long-term allograft survival in only 1 of 30 recipients. Moreover, adenoviral-mediated Fas ligand gene transfer was complicated by transient, dose-dependent islet dysfunction, perhaps contributing to the lack of long-term engraftment. CONCLUSION These data suggest that adenoviral-mediated Fas ligand expression may impair normal islet function in vivo, and indicate that alternative strategies for Fas ligand transgene delivery may be required in this setting.

Colonic dysplasia and cancer in inflammatory bowel disease

Extracolonic malignancies are a relatively rare complication of inflammatory bowel disease. In contrast, colorectal cancer remains a major concern for patients with long-standing UC. The best available evidence suggests that patients with long-standing Crohns colitis are at similar risk for colorectal cancer as those patients with long-standing UC. In patients with UC, the magnitude of this increased risk appears to be greater in patients with more extensive colonic involvement. It appears that the magnitude of this risk increases with increasing duration of disease, at least in UC. Whether this reflects the increased risk of cancer that occurs with the aging process or a separate phenomena distinct to UC is unclear. To date, the methods available to reduce the risk of cancer are less than optimal. Although surgical procedures eliminate the risk, the mental and physical sequelae of these procedures can be substantial. Surveillance with colonoscopic biopsies is likely effective in reducing although not eliminating the risk of colorectal cancer. Efforts to develop chemopreventative agents and improved surveillance methods remain areas of active investigation.

IMMUNOSUPPRESSION THROUGH BLOCKADE OF CD28:B7-MEDIATED COSTIMULATORY SIGNALS

It is now well established that T cells require two signals for activation and effector function. The first signal is provided through the T cell receptor for antigen. The best-characterized pathway which provides the second, or costimulatory, signal is through the CD28 receptor on the surface of T cells. In vitro, ligation of the T cell receptor without a second signal induces a long-lived state of anergy in T cells. CD28 has two known ligands, B7-1 and B7-2, expressed on activated antigen-presenting cells. A soluble fusion protein called CTLA4Ig has been produced which binds B7-1 and B7-2 and acts as a competitive inhibitor of CD28. In vitro and in vivo studies with CTLA4Ig demonstrate that it is an extremely effective immunosuppressive agent in models of transplantation and autoimmunity. Mechanistic studies indicate that CTLA4Ig may work by partially inhibiting the expansion of antigen-reactive cells and inducing anergy in the residual population.

Evaluation of polypoid lesions in inflammatory bowel disease

This article discusses patients with inflammatory bowel disease (IBD), a group which is at increased risk for colorectal carcinoma based on extent and duration of their disease. Patients with chronic IBD (at least 8-10 years duration) should be screened with colonoscopy every 1 to 2 years with multiple jumbo biopsies every 10 cm through the entire colon. Patients with sporadic adenomas can be followed after complete polypectomy, whereas patients with adenoma-like dysplasia-associated lesion or mass (DALMs) need increased surveillance. Patients with flat dysplasia or non adenoma-like DALMs are at high risk for progression and should undergo colectomy. The patients who have indeterminate lesions can be differentiated based on the endoscopic, histologic, and molecular features of the lesion. Long-term follow-up is necessary to determine the natural history of these lesions.