Experimental autoimmune uveitis: molecular mimicry and oral tolerance

Oral mixture of autologous colon-extracted proteins for the Crohn’s disease: A double-blind trial

AIM: To evaluate the safety and efficacy of oral administration of Alequel™, an autologous protein-containing colon extract.

METHODS: A total of 43 patients were enrolled in a randomized, placebo-controlled, double-blind trial. Patients were orally administered with autologous protein-containing colon extract three doses of autologous study drug per week for 15 wk, for a total of 45 doses. Patients were followed for safety parameters. Remission was defined as a Crohn’s disease activity index (CDAI) score of less than or equal to 150. All patients were followed for changes in subsets of T cells by fluorescence-activated cell sorting analysis.

RESULTS: Analysis was performed on a total number of evaluable patients of 14 in the study drug group and 15 in the placebo group. Treatment was well tolerated by all patients. No major treatment-related adverse events were reported or observed in any of the treated patients during the feeding or follow-up periods. Between weeks 6 and 9 of the study, six of the 14 (43%) evaluable subjects who received the study drug achieved a CDAI of 150 or lower. In contrast, five of the 15 (33%) evaluable subjects in the placebo group achieved remission. Between weeks 9 and 12, the remission rates were 50% and 33% for the drug group and placebo group, respectively. Among the drug-treated subjects who achieved remission, the effect of the drug was judged as stable in eight of the 14 subjects as measured by at least two CDAI scores indicating remission in the 15-wk treatment period. A decreased percentage of peripheral natural killer T regulatory cells (a decrease of 28% vs an increase of 16%) and an increased ratio of CD4⁺/CD8⁺ T lymphocytes (an increase of 11% vs a decrease of 9%) were noted in subjects with a significant clinical response.

CONCLUSION: Oral administration of the autologous colonic extract could be a safe and effective for the treatment of patients with moderate to severe Crohn’s disease.

Role of endoplasmic reticulum stress in rheumatoid arthritis pathogenesis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by abnormal proliferation of synoviocytes, leukocyte infiltration, and angiogenesis. The endoplasmic reticulum (ER) is the site of biosynthesis for all secreted and membrane proteins. The accumulation of unfolded proteins in the ER leads to a condition known as ER stress. Failure of the ER's adaptive capacity results in abnormal activation of the unfolded protein response. Recently, we have demonstrated that ER stress-associated gene signatures are highly expressed in RA synovium and synovial cells. Mice with Grp78 haploinsufficiency exhibit the suppression of experimentally induced arthritis, suggesting that the ER chaperone GRP78 is crucial for RA pathogenesis. Moreover, increasing evidence has suggested that GRP78 participates in antibody generation, T cell proliferation, and pro-inflammatory cytokine production, and is therefore one of the potential therapeutic targets for RA. In this review, we discuss the putative, pathophysiological roles of ER stress and GRP78 in RA pathogenesis.

Oral tolerance: can we make it work?

Mucosal tolerance remains an attractive approach for the treatment of autoimmune and inflammatory diseases. The agents used in these treatments lack toxicity, can be easily administered, and enable the promotion of antigen-specific immune responses. The limited success of clinical trials over the past 2 decades has led to the fear that the beneficial effect observed in animal models cannot be repeated in humans. Successful application of mucosal tolerance for the treatment of human diseases will depend on strategies that target the correct cells in the gut-liver axis, improve antigen presentation, alter the administered dose and formulations, utilize potent mucosal adjuvants, develop immune biomarkers enabling follow-up of the effect, utilize combination therapies with other immune modulatory agents, and target the right patient populations. Here, we discuss 12 of the major questions related to oral tolerance and its clinical application to humans with immune-mediated disorders.

The cancer stem cell: evidence for its origin as an injured autoreactive T cell

This review explores similarities between lymphocytes and cancer cells, and proposes a new model for the genesis of human cancer. We suggest that the development of cancer requires infection(s) during which antigenic determinants from pathogens mimicking self-antigens are co-presented to the immune system, leading to breaking T cell tolerance. Some level of autoimmunity is normal and necessary for effective pathogen eradication. However, autoreactive T cells must be eliminated by apoptosis when the immune response is terminated. Apoptosis can be deficient in the event of a weakened immune system, the causes of which are multifactorial. Some autoreactive T cells suffer genomic damage in this process, but manage to survive. The resulting cancer stem cell still retains some functions of an inflammatory T cell, so it seeks out sites of inflammation inside the body. Due to its defective constitutive production of inflammatory cytokines and other growth factors, a stroma is built at the site of inflammation similar to the temporary stroma built during wound healing. The cancer cells grow inside this stroma, forming a tumor that provides their vascular supply and protects them from cellular immune response.

As cancer stem cells have plasticity comparable to normal stem cells, interactions with surrounding normal tissues cause them to give rise to all the various types of cancers, resembling differentiated tissue types. Metastases form at an advanced stage of the disease, with the proliferation of sites of inflammation inside the body following a similar mechanism. Immunosuppressive cancer therapies inadvertently re-invigorate pathogenic microorganisms and parasitic infections common to cancer, leading to a vicious circle of infection, autoimmunity and malignancy that ultimately dooms cancer patients. Based on this new understanding, we recommend a systemic approach to the development of cancer therapies that supports rather than antagonizes the immune system.

The pathology and pathogenesis of retinal vasculitis

Retinal vasculitis is a rare, but potentially blinding intraocular inflammatory condition with diverse aetiology. Although commonly idiopathic, it has a strong association with systemic inflammatory diseases known to involve other areas of the central nervous system, most notably Behcet's disease, sarcoidosis, systemic lupus erythematosis and multiple sclerosis. This article describes the clinicopathologic features of retinal vasculitis and its visually damaging sequelae, reviewing available human histopathologic studies and work with experimental models to discuss the pathogenesis and immunopathology. Evidence indicates that noninfective retinal vasculitis is an autoimmune condition that may be induced by antecedent infection with microbes cross-reacting with putative autoantigens, influenced by genetic susceptibility of both HLA associations and cytokine polymorphisms. The growing understanding of the cellular mechanisms involved in the effector immune response is already providing a rationale for more specific therapeutic approaches.

Human retinal S-antigen: T cell epitope mapping in posterior uveitis patients

Uveitis, an intraocular inflammatory disease which affects the uveal tract and the retina of the eye in humans, is one of the major causes of visual impairment. Posterior uveitis is often associated with inflammation of the retina and vitreous. Unfortunately, etiological diagnosis of the disease is not possible in the majority of patients. It is generally felt that an autoimmune mechanism may be involved in so-called idiopathic cases. The role of retinal S-antigen, its 20 linear peptides spanning the entire sequence, and 2 additional peptides, known to be uveitopathogenic in experimental animals, was studied in 26 patients with uveitis. Lymphocyte proliferative response was tested in vitro to identify the epitopes of S-antigen involved and to establish their role in the pathogenesis of uveitis. Of 26 uveitis patients tested, 11 showed a significant T cell proliferative response in vitro to at least 1 antigen used. None among the controls showed any response to the peptides or native S-antigen used in this study. We have found that uveitis patients respond most frequently to peptide 4 (61--80), peptide 5 (81--100), peptide 8 (141--160), peptide 9 (161--180), peptide 12 (221--240), and peptide 13 (241--260) of the human S-antigen. These results further confirm that autoimmunity to retinal S-antigen may play a role in the etiopathogenesis of a subset of patients with idiopathic uveitis.

Activation of autoreactive T cells by peptides from human pathogens

Activation of autoreactive T cells is a necessary-but not sufficient-step in the development of T cell mediated autoimmunity. Autoreactive T cells can be activated by viral and bacterial peptides that meet the structural requirements for MHC molecule binding and T cell receptor recognition. Due to the degenerate nature of MHC class II molecule binding motifs and a certain degree of flexibility in T cell receptor recognition, such microbial peptides have been found to be quite distinct in their primary sequence from the self-peptide they mimic.