Oral tolerance for the treatment of autoimmune diseases

Improved Joint Health Following Oral Administration of Glycosaminoglycans with Native Type II Collagen in a Rabbit Model of Osteoarthritis

Simple Summary

Osteoarthritis is an incurable chronic disease. For this reason, new therapies are constantly emerging to improve clinical signs and the quality of life of our pets. Chondroitin sulfate, glucosamine and hyaluronic acid have been proven effective and are the most widely used in many formulations. In the present study, adding native type II collagen to the combination of chondroitin sulfate, glucosamine and hyaluronic acid showed improvements on osteoarthritis progression in an experimental model of osteoarthritis induced by transection of the cranial cruciate ligament of the knee in New Zealand white rabbits. Disease progression was monitored at different time points using magnetic resonance imaging biomarkers, measurement of hyaluronic acid in synovial fluid, and macroscopic and microscopic evaluations of cartilage, synovial membrane and subchondral bone. Overall, our results showed that adding native type II collagen to a combination of glycosaminoglycans allows a significantly slower osteoarthritis progression, compared to glycosaminoglycans alone.

Abstract

A prospective, experimental, randomized, double blinded study was designed to evaluate the effects of glycosaminoglycans, with or without native type II collagen (NC), in an osteoarthritis model induced by cranial cruciate ligament transection. The following compounds were tested: chondroitin sulfate (CS), glucosamine hydrochloride (GlHCl), hyaluronic acid (HA) and NC. Fifty-four female 12-week-old New Zealand rabbits were classified into three groups: CTR (control–no treatment), CGH (CS + GlHCl + HA) and CGH-NC (CS + GlHCl + HA + NC). Each group was subdivided into three subgroups according to survival times of 24, 56 and 84 days. Over time, all rabbits developed degenerative changes associated with osteoarthritis. CGH-NC showed significantly improved values on macroscopic evaluation, compared to CTR and CGH. Microscopically, significantly better results were seen with CGH and CGH-NC, compared to CTR, and synovial membrane values were significantly better with CGH-NC compared to CGH. A significant improvement in magnetic resonance imaging biomarkers was also observed with CGH-NC in cartilage transversal relaxation time (T2) and subchondral bone D2D fractal dimension in the lateral condyle. In conclusion, our results show beneficial effects on joint health of CGH and CGH-NC and also supports that adding NC to CGH results in even greater efficacy.

Possible roles of anti-type II collagen antibody and innate immunity in the development and progression of diabetic retinopathy

The pathogenesis of both diabetic retinopathy (DR) and rheumatoid arthritis (RA) has recently been considered to involve autoimmunity. Serum and synovial fluid levels of anti-type II collagen antibodies increase early after the onset of RA, thus inducing immune responses and subsequent hydrarthrosis and angiogenesis, which resemble diabetic macular edema and proliferative DR (PDR), respectively. We previously reported that DR is also associated with increased serum levels of anti-type II collagen antibodies. Retinal hypoxia in DR may induce pericytes to express type II collagen, resulting in autoantibody production against type II collagen. As the result of blood-retinal barrier disruption, anti-type II collagen antibodies in the serum come into contact with type II collagen around the retinal vessels. A continued loss of pericytes and type II collagen around the retinal vessels may result in a shift of the immune reaction site from the retina to the vitreous. It has been reported that anti-inflammatory M2 macrophages increased in the vitreous of PDR patients, accompanied by the activation of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, a key regulator of innate immunity. M2 macrophages promote angiogenesis and fibrosis, which might be exacerbated and prolonged by dysregulated innate immunity.

Targeted delivery of mycophenolic acid to the mesenteric lymph node using a triglyceride mimetic prodrug approach enhances gut-specific immunomodulation in mice

The mesenteric lymph nodes (MLN) are a key site for the generation of adaptive immune responses to gut-derived antigenic material and immune cells within the MLN contribute to the pathophysiology of a range of conditions including inflammatory and autoimmune diseases, viral infections, graft versus host disease and cancer. Targeting immunomodulating drugs to the MLN may thus be beneficial in a range of conditions. This paper investigates the potential benefit of targeting a model immunosuppressant drug, mycophenolic acid (MPA), to T cells in the MLN, using a triglyceride (TG) mimetic prodrug approach. We confirmed that administration of MPA in the TG prodrug form (MPA-TG), increased lymphatic transport of MPA-related species 83-fold and increased MLN concentrations of MPA >20 fold, when compared to MPA alone, for up to 4 h in mice. At the same time, the plasma exposure of MPA and MPA-TG was similar, limiting the opportunity for systemic side effects. Confocal microscopy and flow cytometry studies with a fluorescent model prodrug (Bodipy-TG) revealed that the prodrug accumulated in the MLN cortex and paracortex at 5 and 10 h following administration and was highly associated with B cells and T cells that are found in these regions of the MLN. Finally, we demonstrated that MPA-TG was significantly more effective than MPA at inhibiting CD4⁺ and CD8⁺ T cell proliferation in the MLN of mice in response to an oral ovalbumin antigen challenge. In contrast, MPA-TG was no more effective than MPA at inhibiting T cell proliferation in peripheral LN when mice were challenged via SC administration of ovalbumin. This paper provides the first evidence of an in vivo pharmacodynamic benefit of targeting the MLN using a TG mimetic prodrug approach. The TG mimetic prodrug technology has the potential to benefit the treatment of a range of conditions where aberrant immune responses are initiated in gut-associated lymphoid tissues.

Effects of probiotics on salivary cytokines and immunoglobulines: a systematic review and meta-analysis on clinical trials

Findings on the effects of probiotics on salivary cytokines and immunoglobulines have been conflicting. We aimed to perform a systematic review and meta-analysis on clinical trials that examined the effects of oral intake and local administration of probiotics on salivary cytokines and immunoglobulines in adults. We searched PubMed, MEDLINE, SCOPUS, EMBASE, and Google Scholar up to April 2020 for all relevant published papers assessing probiotic intakes and salivary cytokines and immunoglobulines. We included all randomized clinical trials that investigated the effect of oral probiotic supplementation or lozenges tablets on inflammatory biomarkers in adults. Studies that reported their effect sizes as mean ± SD or mean ± SEM were included. After excluding non-relevant papers, 8 studies remained in this review. Combining findings from 3 studies with 4 effect sizes, we found no significant reduction in salivary IgA concentrations after oral probiotic supplementation [weighted mean difference (WMD): -0.26; 95% CI: (-0.86, 0.35)]. A significant increase in salivary IL-1β concentrations reached after local probiotic supplementation (WMD: 28.21; 95% CI: 18.42, 38.01); however, no significant changes in salivary IL-6 concentrations after local probiotic supplementation was found (WMD: 0.36; 95% CI: -0.85, 1.56). We observed a significant increase in salivary IL-8 concentrations after local probiotic supplementation (WMD: 31.82; 95% CI: 27.56, 36.08). In case of salivary IL-10 concentrations after local probiotic administration, no significant reduction was seen (WMD: -0.02; 95% CI: -0.10, 0.06). we found that oral and local administrations of probiotics might influence some of salivary cytokines. However, additional clinical trials are required to examine these effects on further pro- and anti-inflammatory cytokines and immunoglobulines.

LAP+CD4+ T cells are elevated among the peripheral blood mononuclear cells and tumor tissue of patients with hepatocellular carcinoma

The purpose of the present study was to investigate the role of latency-associated peptide (LAP)⁺CD4⁺T cells in hepatocellular carcinoma (HCC) immunity. Flow cytometric analysis was performed to detect the proportion of LAP⁺CD4⁺ T cells among the peripheral blood mononuclear cells (PBMCs) of 30 HBV-infected HCC patients at the pre-operative and post-operative stages, as well as 30 hepatitis B virus (HBV)-infected volunteers as a control group. Furthermore, tumor tissues and peri-tumor tissues from 28 patients with HCC, as well as hepatic tissues from 28 HBV-infected patients with benign lesions were subjected to immunohistochemical analysis with double staining for LAP and CD4, and the average number of the LAP⁺CD4⁺T cells in each visual field was quantified. The results indicated that the proportion of LAP+CD4+ T cells in the PBMCs of patients with HCC was significantly higher than that in the control group (1.84±0.85 vs. 0.73±0.39%, P=0.019), while it was significantly reduced after the operation (1.07±0.35, P=0.021), but still slightly, if not significantly, higher compared with that in the control group (P=0.342). Furthermore, the number of LAP⁺CD4⁺ T cells per high-magnification microscopic field (magnification, ×400) in the HCC tissues was 11.25±3.00, which was significantly higher than that in the peri-cancer tissues (5.75±1.00) and that in the HBV-infected hepatic tissues around benign lesions (2.61±0.83). In peri-cancer tissues, LAP⁺CD4⁺ T cells were also significantly more abundant than in control tissues. Furthermore, in the HCC tissues, LAP⁺CD4⁺ T cells were present as clusters in the tumor stroma and closely associated with CD4⁺ T lymphocytes. By contrast, in the peri-cancer liver tissues and HBV-infected hepatic tissues around benign lesions, LAP⁺CD4⁺ T cells were sparsely distributed. LAP⁺CD4⁺ T cells have marked inhibitory effects, and in the peripheral blood and tumor tissues of patients with HCC, they have an important role in the suppression of anti-tumor immunity and in the immune evasion of tumor cells.

Regulatory T Cell-Mediated Tissue Repair

Regulatory T-cells (Treg cells) are a specific group of T-cells that maintain immune homeostasis by counteracting the immune responses of conventional T-cells. So far, the therapeutic applications of Treg cells have focused on the treatment of autoimmune diseases, as depletion of Treg cells or Treg-related genes is known to cause autoimmune defects. However, Treg cells can be a potential solution for tissue repair as they can terminate the pro-inflammatory phase and initiate the anti-inflammatory or regenerative phase at the tissue injury site. This review summarizes the known characteristics of Treg cells and lists examples of their therapeutic applications. The use of Treg cells in the treatment of myocardial infarctions, skeletal muscle injuries, and ischemia injuries has revealed their potential as a promising tissue repair method. We have also discussed the limitations and scope of Treg cells in tissue repair.

Innovative Approaches for Immune Tolerance to Factor VIII in the Treatment of Hemophilia A

Hemophilia A (coagulation factor VIII deficiency) is a debilitating genetic disorder that is primarily treated with intravenous replacement therapy. Despite a variety of factor VIII protein formulations available, the risk of developing anti-dug antibodies (“inhibitors”) remains. Overall, 20–30% of patients with severe disease develop inhibitors. Current clinical immune tolerance induction protocols to eliminate inhibitors are not effective in all patients, and there are no prophylactic protocols to prevent the immune response. New experimental therapies, such as gene and cell therapies, show promising results in pre-clinical studies in animal models of hemophilia. Examples include hepatic gene transfer with viral vectors, genetically engineered regulatory T cells (Treg), in vivo Treg induction using immune modulatory drugs, and maternal antigen transfer. Furthermore, an oral tolerance protocol is being developed based on transgenic lettuce plants, which suppressed inhibitor formation in hemophilic mice and dogs. Hopefully, some of these innovative approaches will reduce the risk of and/or more effectively eliminate inhibitor formation in future treatment of hemophilia A.

Immune Response of Healthy Adults to the Ingested Probiotic Lactobacillus casei Shirota

Daily ingestion of a probiotic drink containing Lactobacillus casei Shirota (LcS; 1.3 × 10¹⁰ live cells) by healthy adults for (1) 4-week LcS, (2) 6-week discontinuation of LcS and (3) a final 4 weeks of LcS was investigated. There was a significant increase in expression of the T cell activation marker CD3⁺ CD69⁺ in ex vivo unstimulated blood cells at weeks 10 and 14, and there was a significant increase in the NK cell marker CD3⁺ CD16/56⁺ in ex vivo unstimulated blood cells at weeks 4, 10 and 14. Expression of the NK cell activation marker CD16/56⁺ CD69⁺ in ex vivo unstimulated blood cells was 62% higher at week 10 and 74% higher at week 14. Intracellular staining of IL-4 in ex vivo unstimulated and PMA-/ionomycin-stimulated CD3⁺ β7⁺ integrin blood cells was significantly lower at weeks 10 and 14. Intracellular staining of IL-12 in ex vivo unstimulated and LPS-stimulated CD14⁺ blood cells was significantly lower at weeks 4, 10 and 14. Intracellular staining of TNF-α in LPS-stimulated CD14⁺ blood cells was significantly lower at weeks 4, 10 and 14. Mucosal salivary IFN-γ, IgA1 and IgA2 concentrations were significantly higher at week 14, but LcS did not affect systemic circulating influenza A-specific IgA or IgG and tetanus-specific IgG antibody levels. In addition to the decrease in CD3⁺ β7⁺ integrin cell IL-4 and a reduced CD14⁺ cell pro-inflammatory cytokine profile, at week 14 increased expression of activation markers on circulating T cells and NK cells and higher mucosal salivary IgA1 and IgA2 concentration indicated a secondary boosting effect of LcS.

Type 1 diabetes: A predictable disease

Type 1 diabetes (T1D) is an autoimmune disease characterized by loss of insulin producing beta cells and reliance on exogenous insulin for survival. T1D is one of the most common chronic diseases in childhood and the incidence is increasing, especially in children less than 5 years of age. In individuals with a genetic predisposition, an unidentified trigger initiates an abnormal immune response and the development of islet autoantibodies directed against proteins in insulin producing beta cells. There are currently four biochemical islet autoantibodies measured in the serum directed against insulin, glutamic decarboxylase, islet antigen 2, and zinc transporter 8. Development of islet autoantibodies occurs before clinical diagnosis of T1D, making T1D a predictable disease in an individual with 2 or more autoantibodies. Screening for islet autoantibodies is still predominantly done through research studies, but efforts are underway to screen the general population. The benefits of screening for islet autoantibodies include decreasing the incidence of diabetic ketoacidosis that can be life threatening, initiating insulin therapy sooner in the disease process, and evaluating safe and specific therapies in large randomized clinical intervention trials to delay or prevent progression to diabetes onset.

Oral tolerance to cancer can be abrogated by T regulatory cell inhibition

Oral administration of tumour cells induces an immune hypo-responsiveness known as oral tolerance. We have previously shown that oral tolerance to a cancer is tumour antigen specific, non-cross-reactive and confers a tumour growth advantage. We investigated the utilisation of regulatory T cell (Treg) depletion on oral tolerance to a cancer and its ability to control tumour growth. Balb/C mice were gavage fed homogenised tumour tissue--JBS fibrosarcoma (to induce oral tolerance to a cancer), or PBS as control. Growth of subcutaneous JBS tumours were measured; splenic tissue excised and flow cytometry used to quantify and compare systemic Tregs and T effector (Teff) cell populations. Prior to and/or following tumour feeding, mice were intraperitoneally administered anti-CD25, to inactivate systemic Tregs, or given isotype antibody as a control. Mice which were orally tolerised prior to subcutaneous tumour induction, displayed significantly higher systemic Treg levels (14% vs 6%) and faster tumour growth rates than controls (p<0.05). Complete regression of tumours were only seen after Treg inactivation and occurred in all groups--this was not inhibited by tumour feeding. The cure rates for Treg inactivation were 60% during tolerisation, 75% during tumour growth and 100% during inactivation for both tolerisation and tumour growth. Depletion of Tregs gave rise to an increased number of Teff cells. Treg depletion post-tolerisation and post-tumour induction led to the complete regression of all tumours on tumour bearing mice. Oral administration of tumour tissue, confers a tumour growth advantage and is accompanied by an increase in systemic Treg levels. The administration of anti-CD25 Ab decreased Treg numbers and caused an increase in Teffs. Most notably Treg cell inhibition overcame established oral tolerance with consequent tumor regression, especially relevant to foregut cancers where oral tolerance is likely to be induced by the shedding of tumour tissue into the gut.

Impaired lymphocyte profile in schistosomiasis patients with periportal fibrosis

The Th2 immune response in chronic schistosomiasis is associated with the development of periportal fibrosis. However, little is known about the phenotype and activation status of T cells in the process. Objective. To evaluate the profile of T cells in schistosomiasis patients with periportal fibrosis. Methods. It was a cross-sectional study, conducted in the village of Agua Preta, Bahia, Brazil, which included 37 subjects with periportal fibrosis determined by ultrasound. Peripheral blood mononuclear cells were obtained by the Ficcol-hypaque gradient and the frequency of T cells expressing the surface markers CD28, CD69, CD25, and CTLA-4 was determined by flow cytometry. Results. The frequency of CD4⁺CD28⁺ T lymphocytes was higher in individuals with moderate to severe fibrosis compared to patients with incipient fibrosis. We did not observe any significant difference in the frequency of CD4⁺ T cells expressing CD69 among groups of individuals. There was also no significant difference in the frequency of CD8⁺ T cells expressing CD28 or CD69 among the studied groups. Individuals with moderate to severe fibrosis presented a lower frequency of CD8⁺ T cells, CD4⁺CD25^high T cells, and CD4⁺CTLA-4⁺ T cells when compared to patients without fibrosis or incipient fibrosis. The frequency of CD4⁺CD25^low cells did not differ between groups. Conclusion. The high frequency of activated T cells coinciding with a low frequency of putative Treg cells may account for the development of periportal fibrosis in human schistosomiasis.

Update on allergy immunotherapy: American Academy of Allergy, Asthma & Immunology/European Academy of Allergy and Clinical Immunology/PRACTALL consensus report

Allergy immunotherapy (AIT) is an effective treatment for allergic asthma and rhinitis, as well as venom-induced anaphylaxis. In addition to reducing symptoms, AIT can change the course of allergic disease and induce allergen-specific immune tolerance. In current clinical practice immunotherapy is delivered either subcutaneously or sublingually; some allergens, such as grass pollen, can be delivered through either route, whereas others, such as venoms, are only delivered subcutaneously. Both subcutaneous and sublingual immunotherapy appear to have a duration of efficacy of up to 12 years, and both can prevent the development of asthma and new allergen sensitivities. In spite of the advances with AIT, safer and more effective AIT strategies are needed, especially for patients with asthma, atopic dermatitis, or food allergy. Novel approaches to improve AIT include use of adjuvants or recombinant allergens and alternate routes of administration. As part of the PRACTALL initiatives, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma & Immunology nominated an expert team to develop a comprehensive consensus report on the mechanisms of AIT and its use in clinical practice, as well as unmet needs and ongoing developments in AIT. This resulting report is endorsed by both academies.

Changes in antigen-specific T-cell number and function during oral desensitization in cow's milk allergy enabled with omalizumab

Food allergy is a major public health problem, for which there is no effective treatment. We examined the immunological changes that occurred in a group of children with significant cow's milk allergy undergoing a novel and rapid high-dose oral desensitization protocol enabled by treatment with omalizumab (anti-immunoglobulin (Ig)E monoclonal antibodies). Within a week of treatment, the CD4(+) T-cell response to milk was nearly eliminated, suggesting anergy in, or deletion of, milk-specific CD4(+) T cells. Over the following 3 months while the subjects remained on high doses of daily oral milk, the CD4(+) T-cell response returned, characterized by a shift from interleukin-4 to interferon-γ production. Desensitization was also associated with reduction in milk-specific IgE and a 15-fold increase in milk-specific IgG4. These studies suggest that high-dose oral allergen desensitization may be associated with deletion of allergen-specific T cells, without the apparent development of allergen-specific Foxp3(+) regulatory T cells.

Nasal immunization with different forms of heat shock protein-65 reduced high-cholesterol-diet-driven rabbit atherosclerosis

Heat shock protein-65 (Hsp65) is an important pro-atherogenic factor, but nasal immunization of Hsp65 can induce immune tolerance and reduce atherosclerotic inflammation. Here, we describe the effects of different forms of Hsp65 antigen inoculated, i.e. Hsp65 DNA, Hsp65 protein, Hsp65 DNA prime combined with Hsp65 protein boost, on high-cholesterol-diet-driven rabbit atherosclerosis lesions. The results showed that sera anti-Hsp65 IgG antibodies were lower induced and protective anti-Hsp65 IgA in nasal cavity and lung were induced after rabbits were immunized with different forms of Hsp65. However, the avidity between Hsp65 IgG antibody and antigen is different. Hsp65 DNA prime-protein boost could further improve the avidity compared with Hsp65 DNA immunization alone, but only immunization with Hsp65 protein alone obtain the best avidity. In addition, more protective IL-10 and less adverse IFN-γ were produced and sera TC and LDL-C were decreased obviously at different extents in immunized groups. As a result, atherosclerosis lesions were significantly attenuated, but only nasal immunization with Hsp65 protein alone may be the best effective form of Hsp65 antigen to control atherosclerotic lesions. The results demonstrated that different forms of Hsp65 antigen could produce different effects in the treatment of atherosclerosis. Immunization mucosally with Hsp65 protein could be a promising therapeutic method for atherosclerosis.

Animal models of hemophilia

The X-linked bleeding disorder hemophilia is caused by mutations in coagulation factor VIII (hemophilia A) or factor IX (hemophilia B). Unless prophylactic treatment is provided, patients with severe disease (less than 1% clotting activity) typically experience frequent spontaneous bleeds. Current treatment is largely based on intravenous infusion of recombinant or plasma-derived coagulation factor concentrate. More effective factor products are being developed. Moreover, gene therapies for sustained correction of hemophilia are showing much promise in preclinical studies and in clinical trials. These advances in molecular medicine heavily depend on availability of well-characterized small and large animal models of hemophilia, primarily hemophilia mice and dogs. Experiments in these animals represent important early and intermediate steps of translational research aimed at development of better and safer treatments for hemophilia, such a protein and gene therapies or immune tolerance protocols. While murine models are excellent for studies of large groups of animals using genetically defined strains, canine models are important for testing scale-up and for long-term follow-up as well as for studies that require larger blood volumes.

Effect of oral insulin on diabetes-induced intestinal mucosal growth in rats

BACKGROUND

To evaluate the intestinal response to the induction of diabetes and to oral insulin (OI) administration in a rat.

METHODS

Male Sprague-Dawley rats were divided into four experimental groups: control rats, CONTR-INS rats that were treated with OI given in drinking water for 7 days, diabetic rats that were injected with one dose of streptozotocin, and diabetic rats treated with OI. Intestinal structural changes, enterocyte proliferation and enterocyte apoptosis, bax and bcl-2 mRNA and protein levels, insulin receptor expression and ERK protein levels were determined at sacrifice. A one-way ANOVA for comparison, followed by Tukey's test for pair-wise comparison, were used for statistical analysis.

RESULTS

Induction of diabetes resulted in a significant increase in bowel and mucosal weight (P < 0.05), mucosal protein (P < 0.05), villus height and crypt depth in jejunum and ileum (P < 0.05), and mucosal DNA in ileum (P < 0.05) (vs. control animals). Diabetes also enhances ERK-induced cell proliferation (P < 0.05) and concomitant bax/bcl-2 induced cell apoptosis (P < 0.05). Treatment of diabetic rats with OI resulted in a significant decrease in jejunal protein content (P < 0.05), jejunal and ileal villus height (P < 0.05), and jejunal crypt depth (P < 0.05), as well as an inhibition of ERK-related cell proliferation in ileum (P < 0.05). Expression of insulin receptor was down-regulated following OI administration in both control and diabetic animals.

CONCLUSIONS

Experimental STZ-induced diabetes causes intestinal mucosal growth and enhances enterocyte turnover in a rat model. OI administration diminishes diabetes-accelerated cell turnover and diabetes-induced mucosal hyperplasia.

Specific immunotherapy of experimental myasthenia gravis by a novel mechanism

OBJECTIVE

Myasthenia gravis (MG) and its animal model, experimental autoimmune myasthenia gravis (EAMG), are antibody (Ab)-mediated autoimmune diseases, in which autoantibodies bind to and cause loss of muscle nicotinic acetylcholine receptors (AChRs) at the neuromuscular junction. To develop a specific immunotherapy of MG, we treated rats with ongoing EAMG by intraperitoneal injection of bacterially-expressed human muscle AChR constructs.

METHODS

Rats with ongoing EAMG received intraperitoneal treatment with the constructs weekly for 5 weeks beginning after the acute phase. Autoantibody concentration, subclassification, and specificity were analyzed to address the underlying therapeutic mechanism.

RESULTS

EAMG was specifically suppressed by diverting autoantibody production away from pathologically relevant specificities directed at epitopes on the extracellular surface of muscle AChRs toward pathologically irrelevant epitopes on the cytoplasmic domain. A mixture of subunit cytoplasmic domains was more effective than a mixture containing both extracellular and cytoplasmic domains or than only the extracellular domain of alpha1 subunits.

INTERPRETATION

Therapy using only cytoplasmic domains, which lack pathologically relevant epitopes, avoids the potential liability of boosting the pathological response. Use of a mixture of bacterially-expressed human muscle AChR cytoplasmic domains for antigen-specific immunosuppression of myasthenia gravis has the potential to be specific, robust, and safe.

Tobacco, a highly efficient green bioreactor for production of therapeutic proteins

Molecular farming of pharmaceuticals in plants has the potential to provide almost unlimited amounts of recombinant proteins for use in disease diagnosis, prevention or treatment. Tobacco has been and will continue to be a major crop for molecular farming and offers several practical advantages over other crops. It produces significant leaf biomass, has high soluble protein content and is a non-food crop, minimizing the risk of food-chain contamination. This, combined with its flexibility and highly-efficient genetic transformation/regeneration, has made tobacco particularly well suited for plant-based production of biopharmaceutical products. The goal of this review is to provide an update on the use of tobacco for molecular farming of biopharmaceuticals as well the technologies developed to enhance protein production/purification/efficacy. We show that tobacco is a robust biological reactor with a multitude of applications and may hold the key to success in plant molecular farming.

Oral insulin - a review of current status

Oral insulin is one of the most exciting areas of development in the treatment of diabetes because of its potential benefit in patient convenience, rapid insulinization of liver, adequate insulin delivery avoiding peripheral hyperinsulinaemia while potentially avoiding adverse effects of weight gain and hypoglycaemia. Growing evidence that earlier initiation of intensive insulin therapy produces sustained tight glycaemic control resulting in substantial delay in complications makes an effective oral insulin product even more vital for the management of patients with diabetes. Despite knowledge of this unmet medical need, oral delivery of insulin has been unsuccessful because of several barriers. For several decades, researchers have tried to develop oral insulin using various technologies without much clinical or commercial success. This review summarizes the development status of oral insulins which are publicly reported to be undergoing clinical studies. Currently, two oral insulin products are in an advanced stage of clinical development and first data from long-term therapy are expected to be available in the second half of 2010.

Impaired small-world efficiency in structural cortical networks in multiple sclerosis associated with white matter lesion load

White matter tracts, which play a crucial role in the coordination of information flow between different regions of grey matter, are particularly vulnerable to multiple sclerosis. Many studies have shown that the white matter lesions in multiple sclerosis are associated with focal abnormalities of grey matter, but little is known about the alterations in the coordinated patterns of cortical morphology among regions in the disease. Here, we used cortical thickness measurements from structural magnetic resonance imaging to investigate the relationship between the white matter lesion load and the topological efficiency of structural cortical networks in multiple sclerosis. Network efficiency was defined using a 'small-world' network model that quantifies the effectiveness of information transfer within brain networks. In this study, we first classified patients (n = 330) into six subgroups according to their total white matter lesion loads, and identified structural brain networks for each multiple sclerosis group by thresholding the corresponding inter-regional cortical thickness correlation matrix, followed by a network efficiency analysis with graph theoretical approaches. The structural cortical networks in multiple sclerosis demonstrated efficient small-world architecture regardless of the lesion load, an organization that maximizes the information processing at a relatively low wiring cost. However, we found that the overall small-world network efficiency in multiple sclerosis was significantly disrupted in a manner proportional to the extent of total white matter lesions. Moreover, regional efficiency was also significantly decreased in specific brain regions, including the insula and precentral gyrus as well as regions of prefrontal and temporal association cortices. Finally, we showed that the lesions also altered many cortical thickness correlations in the frontal, temporal and parietal lobes. Our results suggest that the white matter lesions in multiple sclerosis might be associated with aberrant neuronal connectivity among widely distributed brain regions, and provide structural (morphological) evidence for the notion of multiple sclerosis as a disconnection syndrome.

Oral administration of Alequel, a mixture of autologous colon-extracted proteins for the treatment of Crohn's disease

The pathogenesis of Crohn's disease involves an immune-mediated damage to the gut mucosa. Current developed therapies are based on the use of immunosuppressive drugs that can lead to significant drug-related adverse responses. There is a need for a therapeutic strategy that is more specific and less global in its effect on the immune system. Oral tolerance is an active process wherein oral administration of antigens is associated with the induction of regulatory cells and the suppression of effector cells directed toward specific and nonspecific antigens. Studies in animal models of experimental colitis suggest that oral administration of proteins extracted from the gut can induce tolerance and alleviate the disease symptoms. Recent clinical trials showed that oral administration of Alequel, an autologous protein-containing colon extract, to patients with Crohn's disease is safe and may be effective as a therapeutic modality for treating the disease. This treatment was associated with disease-associated antigen alterations of the immune response in the patients. Oral administration of Alequel could provide a patient-tailored approach that is side-effect-free for the treatment of patients with Crohn's disease.

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.

Soluble interleukin-10 and transforming growth factor-beta in children with acute exacerbation of allergic asthma

Cytokine-mediated interactions among inflammatory cells may contribute to pathogenesis of allergic asthma. To understand the role of soluble interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) on the disease activity and regulation in asthma, changes in serum concentrations of IL-10 and TGF-beta elaborated by activated T-lymphocyte before and after prednisolone therapy with clinical improvement were determined. Circulating levels of IL-10 and TGF-beta in sera from 16 normal control subjects and in sera from 22 allergic asthmatic children with acute exacerbation and in stable condition were respectively detected by commercially available enzyme-linked immunosorbent assay kits. The mean concentrations of serum IL-10 in asthmatics with acute exacerbation (6.77 +/- 4.08 pg/mL) and during stable condition (5.14 +/- 1.17 pg/mL) were lower than that in control subjects (7.15 +/- 4.72 pg/mL). However, the difference was not statistically significant among these three study groups. The mean concentration of serum TGF-beta in stable asthmatics (40.73 +/- 15.95 pg/mL) was significantly higher than that in asthmatics with acute exacerbation (27.64 +/- 3.66 pg/mL; p < 0.05) and that in healthy control group (28.77 +/- 8.35 pg/mL; p < 0.05), while there was no statistical difference between the latter two groups. This study provides further evidence that serum TGF-beta, rather than IL-10, may play a role in regulation of disease activity and serve as an indicator for clinical control of allergic asthmatics.

Brain imaging in drug R&D

Magnetic resonance imaging (MRI), used as a clinical diagnostic tool since the early 1980s, is rapidly gaining traction as an integral part of the drug development process. Brain imaging research spans a wide area, covering both structure and function, and ranging from the physics and physiology associated with novel acquisition techniques, to the development of sophisticated image processing algorithms. This paper briefly describes two methods on either end of this spectrum: the "pipeline" framework for the fully automated morphometric analysis of brain imaging data, and molecular MRI, which holds promise for the non-invasive detection of molecular targets of new pharmacological compounds. The potential use of these technologies is illustrated by examples of their applications in multiple sclerosis, Alzheimer's disease, and oncology.

Myasthenia gravis and the tops and bottoms of AChRs: antigenic structure of the MIR and specific immunosuppression of EAMG using AChR cytoplasmic domains

The main immunogenic region (MIR), against which half or more of the autoantibodies to acetylcholine receptors (AChRs) in myasthenia gravis (MG) or experimental autoimmune MG (EAMG) are directed, is located at the extracellular end of alpha1 subunits. Rat monoclonal antibodies (mAbs) to the MIR efficiently compete with MG patient autoantibodies for binding to human muscle AChRs. Antibodies bound to the MIR do not interfere with cholinergic ligand binding or AChR function, but target complement and trigger antigenic modulation. Rat mAbs to the MIR also bind to human ganglionic AChR alpha3 subunits, but MG patient antibodies do not. By making chimeras of alpha1 subunits with alpha7 subunits or ACh binding protein, the structure of the MIR and its functional effects are being investigated. Many mAbs to the MIR bind only to the native conformation of alpha1 subunits because they bind to sequences that are adjacent only in the native structure. The MIR epitopes recognized by these mAbs are not recognized by most patient antibodies whose epitopes must be nearby. The presence of the MIR epitopes in alpha1/alpha7 chimeras greatly promotes AChR expression and sensitivity to activation. EAMG can be suppressed by treatment with denatured, bacterially expressed mixtures of extracellular and cytoplasmic domains of human alpha1, beta1, gamma, delta, and epsilon subunits. A mixture of only the cytoplasmic domains not only avoids the potential liability of provoking formation antibodies to pathologically significant epitopes on the extracellular surface, but also potently suppresses the development of EAMG.

ZP3 peptides administered orally suppress murine experimental autoimmune ovarian disease

Experimental autoimmune ovarian disease (AOD) is a T cell-mediated chronic inflammatory disease that may lead to premature ovarian failure. Autoimmune disease can be suppressed by oral administration of autoantigens leading to tolerance. One of the major mechanisms of oral tolerance is induction of regulatory CD4+ T cells that can mediate active suppression by producing immunomodulatory cytokines. However, the role of oral tolerance as a treatment for experimental AOD has received little attention. Therefore, the purpose of this study was to examine the conditions necessary to produce oral tolerance in experimental AOD in B6AF1 female mice. In this study, mice received different doses of peptides of the mouse zona pellucida 3 (pZP3) via gastric intubation for 7 times. After 4 times of oral administration, AOD was induced by immunization with pZP3. The optimal tolerating regimen for oral administration of pZP3 in mice was 10 microg, which decreased morbidity of oophoritis compared to the control group. In this moderate-dose therapeutic group (MD), alterations in the estrous cycle were normalized and CD4+ T cells that were CD25+ increased while those that were CD25- decreased. The severity of autoimmune oophoritis and the titer of ZP autoantibodies were also significantly reduced. These findings suggest that oral administration of pZP3 may be successfully used as an oral tolerance strategy for suppression of AOD.

Dendritic cells: key to fetal tolerance?

Pregnancy is a unique event in which a fetus, despite being genetically and immunologically different from the mother (a hemi-allograft), develops in the uterus. Successful pregnancy implies avoidance of rejection by the maternal immune system. Fetal and maternal immune cells come into direct contact at the decidua, which is a highly specialized mucous membrane that plays a key role in fetal tolerance. Uterine dendritic cells (DC) within the decidua have been implicated in pregnancy maintenance. DC serve as antigen-presenting cells with the unique ability to induce primary immune responses. Just as lymphocytes comprise different subsets, DC subsets have been identified that differentially control lymphocyte function. DC may also act to induce immunologic tolerance and regulation of T cell-mediated immunity. Current understanding of DC immunobiology within the context of mammalian fetal-maternal tolerance is reviewed and discussed herein.

Prediction and prevention of type 1 diabetes: progress, problems, and prospects

Type 1 diabetes mellitus (T1D) arises from selective immunologically mediated destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans with consequent insulin deficiency. This occurs in genetically susceptible individuals and is a cellular-mediated process, presumably a specific reaction to one or more beta-cell proteins (autoantigens), although probably initiated by some environmental factor(s). There is consequent progressive impairment of beta-cell function and decline in beta-cell mass. A secondary humoral immune response is characterized by the appearance of autoantibodies that serve as markers of the immune damage to beta-cells. This insidious T1D disease process evolves over a period of years. The decline in beta-cell function and mass is evidenced metabolically by loss of first-phase insulin response to an intravenous glucose challenge, and later by the appearance of impairment in glycemic regulation, manifested as dysglycemia--usually as impaired glucose tolerance, but occasionally as impaired fasting glucose. Ultimately, the clinical syndrome of T1D becomes evident when the majority of beta-cells have been destroyed and frank hyperglycemia supervenes. Given this sequence of events, for which it is possible to envision intervention to interdict the process, it is not surprising that much research effort has been expended to identify individuals at risk of the disease.

Focal cortical atrophy in multiple sclerosis: relation to lesion load and disability

Multiple sclerosis (MS) is thought to predominantly affect white matter (WM). Recently, however, loss of cortical gray matter has also been described. Little is known about the cause of cortical atrophy in MS, whether it occurs early in the disease course, and whether it affects all cortical regions equally or if there is a preferential pattern of focal cortical atrophy. An automated method was used to compute the thickness at every vertex of the cortical surface of the brains of 425 early relapsing-remitting MS patients. We correlated cortical thickness with the WM lesion load and the Expanded Disability Status Scale score. Mean cortical thickness correlated with WM lesion load and disability. The correlations of cortical thickness with total lesion load and disability were most significant in cingulate gyrus, insula, and associative cortical regions. Conversely, primary sensory, visual, and motor areas showed a less significant relationship. The highest amount of atrophy per lesion volume or disability scale unit was in the anterior cingulate cortex. This study confirms the relation between cortical atrophy, WM lesion load, and disability in MS, and suggests that cortical atrophy occurs even in MS patients with only mild disability. Most interestingly, we show a specific regional pattern of focal atrophy in MS that is distinctively different from the one in normal aging. The predilection of the atrophic process for areas that are heavily inter-connected with other brain regions suggests that interruption of WM tracts by MS plaques contributes, at least in part, to the development of cortical atrophy.

Primer: mechanisms of immunologic tolerance

Successful adaptive immunity against a broad range of pathogens depends on the diversity of randomly generated T-lymphocyte and B-lymphocyte receptors. A subset of these receptors will be self-reactive and must be regulated to prevent autoimmunity. The process of immunologic tolerance addresses this problem by either purging autoreactive receptors from the system or tuning down their reactivity sufficiently to prevent disease. Immature lymphocytes generate a novel receptor during development in the thymus or bone marrow. Engagement of self antigens by these nascent receptors leads to their purging, either by the apoptotic death of the lymphocyte or by the initiation of receptor editing, a process in which the autoreactive receptor is replaced. If the lymphocytes mature further, the activation threshold of autoreactive cells can be tuned by the co-expression of inhibitory receptors or negative signaling molecules, allowing the persistence of the receptor without an increased risk of autoimmunity. T-cell and B-cell receptors that escape these checkpoints can still be regulated in the peripheral immune system by both purging and tuning mechanisms. A separate set of mechanisms, mediated by various regulatory cells, also operates to tune peripheral receptors in a cell-extrinsic fashion. The combined action of these processes ensures that the organism does not suffer autoimmune pathology, even if autoreactive receptors are generated and maintained in the immune system.

Induction of partial immune tolerance to factor VIII through prior mucosal exposure to the factor VIII C2 domain

BACKGROUND

The development of anti-factor VIII (FVIII) neutralizing antibodies (inhibitors) is a significant obstacle to FVIII replacement therapy.

OBJECTIVE

As mucosal administration of an antigen may induce immune tolerance we have evaluated the efficacy of mucosal antigen exposure to achieve tolerance to FVIII.

METHODS

We investigated the effects of oral and nasal administration of the purified FVIII C2 domain (FVIII-C2) to FVIII-deficient BALB/c mice prior to FVIII protein challenge. Mice received oral or nasal doses of FVIII-C2, followed by a subcutaneous challenge of either FVIII-C2 or FVIII. The development of anti-FVIII inhibitors, cytokine production by splenocytes in vitro, and adoptive transfer assays were analyzed.

RESULTS AND CONCLUSIONS

Mucosal administration of FVIII-C2 decreases the titer of anti-FVIII-C2 inhibitors after FVIII-C2 challenge, and decreases the percentage of FVIII-C2 specific antibodies after challenge with full-length FVIII. Tolerance induction to FVIII-C2 is associated with increased IL-10 production by splenocytes in vitro, and can be adoptively transferred to naïve mice. This study is the first to demonstrate that tolerance to the FVIII-C2 domain can be induced via the mucosal route. Based on these results, the potential use of FVIII-specific mucosal tolerance induction as an immunotherapy treatment for anti-FVIII inhibitor development warrants further investigation.

Mechanisms of allergen-specific immunotherapy: T-regulatory cells and more

Activation-induced cell death, anergy, or immune response modulation by regulatory T cells (Treg cells) are essential mechanisms of peripheral T-cell tolerance. Genetic predisposition and environmental instructions tune thresholds for the activation of T cells, other inflammatory cells, and resident tissue cells in allergic diseases. Skewing allergen-specific effector T cells to a Treg-cell phenotype seems to be crucial in maintaining a healthy immune response to allergens and successful allergen-specific immunotherapy. The Treg-cell response is characterized by an abolished allergen-specific T-cell proliferation and the suppressed secretion of T-helper 1- and T-helper 2-type cytokines. Suppressed proliferative and cytokine responses against allergens are induced by multiple suppressor factors, including cytokines such as interleukin-10 (IL-10) and transforming growth factor beta (TGF-beta), and cell surface molecules such as cytotoxic T-lymphocyte antigen-4, programmed death-1, and histamine receptor 2. The increased levels of IL-10 and TGF-beta produced by Treg cells potently suppress IgE production while simultaneously increasing the production of noninflammatory isotypes IgG4 and IgA, respectively. In addition, Treg cells directly or indirectly suppress the activity of effector cells of allergic inflammation, such as mast cells, basophils, and eosinophils. In conclusion, peripheral tolerance to allergens is controlled by multiple active suppression mechanisms on T cells, regulation of antibody isotypes, and suppression of effector cells. The application of current knowledge of Treg cells and related mechanisms of peripheral tolerance may soon lead to more rational and safer approaches to the prevention and cure of allergic disease.

Mechanisms of allergen specific immunotherapy--T-cell tolerance and more

Specific immune suppression and induction of tolerance are essential processes in the regulation and circumvention of immune defence. The balance between allergen-specific T-regulatory (Treg) cells and T helper 2 cells appears to be decisive in the development of allergic and healthy immune response against allergens. Treg cells consistently represent the dominant subset specific for common environmental allergens in healthy individuals. In contrast, there is a high frequency of allergen-specific T helper 2 cells in allergic individuals. A decrease in interleukin (IL)-4, IL-5 and IL-13 production by allergen-specific CD4+ T cells due to the induction of peripheral T cell tolerance is the most essential step in allergen-specific immunotherapy (SIT). Suppressed proliferative and cytokine responses against the major allergens are induced by multiple suppressor factors, such as cytokines like IL-10 and transforming growth factor (TGF)-beta and cell surface molecules like cytotoxic T lymphocyte antigen-4, programmed death-1 and histamine receptor 2. There is considerable rationale for targeting T cells to increase efficacy of SIT. Such novel approaches include the use of modified allergens produced using recombinant DNA technology and adjuvants or additional drugs, which may increase the generation of allergen-specific peripheral tolerance. By the application of the recent knowledge in Treg cells and related mechanisms of peripheral tolerance, more rational and safer approaches are awaiting for the future of prevention and cure of allergic diseases.

Reduced incidence of slowly progressive Heymann nephritis in rats immunized with a modified vaccination technique

A slowly progressive Heymann nephritis (SPHN) was induced in three groups of rats by weekly injections of a chemically modified renal tubular antigen in an aqueous medium. A control group of rats received the chemically unmodified version of the antigen in an aqueous solution. One group of SPHN rats were pre- and post-treated with weekly injections of IC made up of rKF3 and rarKF3 IgM antibody at antigen excess (MIC) (immune complexes [ICs] containing sonicated ultracentrifuged [u/c] rat kidney fraction 3 [rKF3] antigen and IgM antibodies specific against the antigen, at slight antigen excess). One group of SPHN rats were post-treated with MIC 3 weeks after the induction of the disease and one group of SPHN animals received no treatment. The control group of rats received pre- and post-treatment with sonicated u/c rKF3.

The incidence of immune-complex glomerulonephritis (ICGN) in the untreated SPHN rats was 87%, in the pre- and post-treated animals 13%, and in the post-treated-only rats 20%. Rats receiving sonicated ultracentrifuged rKF3 antigen did not develop ICGN.

The present experiment demonstrates that the development of SPHN can be not only prevented but also effectively terminated by our newly developed modified vaccination technique.

Effects of overexpression of IL-10, IL-12, TGF-beta and IL-4 on allergen induced change in bronchial responsiveness

Background

An increasing prevalence of allergic diseases, such as atopic dermatitis, allergic rhinitis and bronchial asthma, has been noted worldwide. Allergic asthma strongly correlates with airway inflammation caused by the unregulated production of cytokines secreted by allergen-specific type-2 T helper (Th2) cells. This study aims to explore the therapeutic effect of the airway gene transfer of IL-12, IL-10 and TGF-β on airway inflammation in a mouse model of allergic asthma.

Methods

BALB/c mice were sensitized to ovalbumin (OVA) by intraperitoneal injections with OVA and challenged by nebulized OVA. Different cytokine gene plasmids or non-coding vector plasmids were instilled daily into the trachea up to one day before the inhalatory OVA challenge phase.

Results

Intratracheal administration of IL-10, IL-12 or TGF-β can efficiently inhibit antigen-induced airway hyper-responsiveness and is able to largely significantly lower the number of eosinophils and neutrophils in bronchoalveolar lavage fluid of ovalbumin (OVA) sensitized and challenged mice during the effector phase. Furthermore, the effect of IL-10 plasmids is more remarkable than any other cytokine gene plasmid. On the other hand, local administration of IL-4 gene plasmids before antigen challenge can induce severe airway hyper-responsiveness (AHR) and airway eosinophilia.

Conclusion

Our data demonstrated that anti- inflammatory cytokines, particularly IL-10, have the therapeutic potential for the alleviation of airway inflammation in murine model of asthma.

Mechanisms of immune suppression by interleukin-10 and transforming growth factor-beta: the role of T regulatory cells

Specific immune suppression and induction of tolerance are essential processes in the regulation and circumvention of immune defence. The balance between allergen-specific type 1 regulatory (Tr1) cells and T helper (Th) 2 cells appears to be decisive in the development of allergy. Tr1 cells consistently represent the dominant subset specific for common environmental allergens in healthy individuals. In contrast, there is a high frequency of allergen-specific interleukin-4 (IL-4)-secreting T cells in allergic individuals. Allergen-specific immunotherapy can induce specific Tr1 cells that abolish allergen-induced proliferation of Th1 and Th2 cells, as well as their cytokine production. Tr1 cells utilize multiple suppressor mechanisms, such as IL-10 and transforming growth factor-beta (TGF-beta) as secreted cytokines and various surface molecules, such as cytotoxic T-lymphocyte antigen 4 and programmed death-1. IL-10 only inhibits T cells stimulated by low numbers of triggered T-cell receptors, which depend on CD28 costimulation. IL-10 inhibits CD28 tyrosine phosphorylation, preventing the binding of phosphatidylinositol 3-kinase p85 and consequently inhibiting the CD28 signalling pathway. In addition, IL-10 and TGF-beta secreted by Tr1 cells skew the antibody production from immunoglobulin E (IgE) towards the non-inflammatory isotypes IgG4 and IgA, respectively. Induction of antigen-specific Tr1 cells can thus re-direct an inappropriate immune response against allergens or auto-antigens using a broad range of suppressor mechanisms.

A double-blind clinical trial for treatment of Crohn's disease by oral administration of Alequel, a mixture of autologous colon-extracted proteins: a patient-tailored approach

OBJECTIVES

In this study, we evaluated the safety and efficacy of a personalized mode of treatment for Crohn's disease (CD) by oral administration of Alequel an extract of autologous colonic proteins.

METHODS

Thirty-one patients with moderate to severe CD were enrolled in a 27-wk randomized, double-blind, placebo-controlled trial. Patients were randomized to receive either a placebo or the study drug prepared from autologous colonic extract.

RESULTS

Oral administration of autologous colonic proteins resulted in clinical remission (58% vs 29%; 46.6% vs 26.6%, using an intention to treat analysis, p= NS), clinical response (67% vs 43%; 53.3% vs 40%, using an intention to treat analysis, p= NS) and improved quality of life (Inflammatory Bowel Disease Questionnaire score improvement 43%vs 12%) in the drug study group, compared to placebo group. No treatment-related adverse events were noted. Only in the study-drug-treated cohort who achieved clinical remission (DR), there was a decreased number of subject-specific, antigen-directed, IFNgamma spot-forming colonies. DR subjects had a lower initial C-reactive protein level than DNOR or placebo subjects, an increased percentage of peripheral blood nature killer T cells, and an increased CD4+/CD8+ T-cell ratio throughout the period of drug administration.

CONCLUSIONS

Oral administration of Alequel is a safe method for treatment of patients with moderate to severe CD, and its efficacy needs to be proven. Several markers may be applicable as surrogate markers for the clinical effect.

Large-scale morphometric analysis of neuroanatomy and neuropathology

Brain imaging research with MRI spans a wide area, covering both structure and function, and ranging from basic research through clinical research to drug design and clinical trials. In recent years there has been a trend towards the collection of very large MRI databases which can allow for the detection of very small group-dependent effects. However, the logistical challenges of analysing such large datasets presents new challenges. This paper describes the "pipeline" framework developed at the Montreal Neurological Institute for the fully automated morphometric analysis of large brain imaging databases. The potential use of these techniques is illustrated by examples of their applications in multiple sclerosis, Alzheimer's disease, and pediatric development.

Oral immune tolerance mediated by suppressor T cells may be responsible for the poorer prognosis of foregut cancers

The poor prognosis of foregut cancers might, in part, be due to the immune tolerising effect of tumour antigens which are shed into the gastrointestinal tract and processed by the gut immune system. This would create a tumour specific tolerance without compromise of global immune functions. Experimental data shows that orally fed cancer tissue induces a non cross reactive attenuation of the cellular anti tumour host responses and confers a growth advantage specific to individual cancers. Although the cellular basis of such pro-tumourogenic responses has yet to be established, it is likely, based on studies of oral tolerance mechanisms, that recruitment of immune suppressive T cells (T(regs)) may be responsible. Abrogation of oral immune tolerance to the tumour by immune based therapy could represent a significant advance in the management of upper gastrointestinal cancers.

Are regulatory T cells the target of venom immunotherapy?

PURPOSE OF REVIEW

Allergen-specific immunotherapy is the only treatment that leads to lifelong tolerance to previously disease-causing allergens by restoring normal immunity against allergens. T-regulatory (TReg) cells are involved in preventing sensitization to allergens and represent a major target for venom- or other allergen-specific immunotherapy.

RECENT FINDINGS

Induction of peripheral tolerance in T cells, which is characterized mainly by suppressed proliferative and cytokine responses against the T-cell epitopes of major allergens, is an essential step in specific immunotherapy. It is initiated by the autocrine action of interleukin-10 and/or transforming growth factor-beta, which are produced by antigen-specific TReg cells. Tolerized T cells can be reactivated to produce distinct T-helper-1 or T-helper-2 cytokine patterns, thus directing allergen-specific immunotherapy toward successful or unsuccessful outcomes. TReg cells directly or indirectly influence effector cells of allergic inflammation, such as mast cells, basophils and eosinophils. In addition, there is accumulating evidence that they may suppress IgE production and induce IgG4 and IgA production against allergens. In addition, histamine released from mast cells and basophils may efficiently contribute to immunoregulation during specific immunotherapy, and affect TReg cells and the production of their cytokines via histamine receptor 2.

SUMMARY

By applying recent knowledge in TReg-cell-dependent mechanisms of peripheral tolerance, more rational and safer approaches to the prevention and cure of venom hypersensitivity may be developed in the future.

Peptide-based instruction of suppressor commitment in naïve T cells and dynamics of immunosuppression in vivo

Recent years have witnessed the revival of suppressor T cells that control immunity by interfering with the generation of effector T-cell function in vivo. The discovery that CD4 T cells with the CD25 surface marker were enriched in suppressor activity enabled further phenotypic and functional analysis of the so-called natural suppressor cells. In vitro characterization showed that these cells were anergic, i.e. did not respond to antigenic stimulation with proliferation and, instead they suppressed other cells through direct cell contact resulting in inhibition of interleukin-2 gene transcription. We have analysed the generation and function of suppressor T cells in T-cell receptor (TCR) transgenic mice. The results showed that such cells can be generated intrathymically when agonist TCR ligands are expressed on thymic epithelial cells. Thus generated cells constitute a lineage of cells committed to suppression only with the ability to survive for prolonged periods of time in the absence of the inducing ligand. Because of appropriate homing receptors such cells can accumulate and proliferate in antigen draining lymphnodes after antigenic stimulation and suppress proliferation and cytokine secretion of CD4 and CD8 T cells as well as CD8 T-cell-mediated cytotoxicity. We also attempted to generate such cells from naïve T cells in secondary lymphoid tissue under conditions where expansion of already preformed suppressor T cells could be excluded. The results showed that subimmunogenic peptide delivery by osmotic minipumps or by peptide containing DEC 205 antibodies yielded CD25+ suppressor cells that were phenotypically and functionally indistinguishable from intrathymically generated suppressor cells. The experiments with DEC205 antibodies revealed (i) dose-dependent proliferation of naïve T cells and (ii) conversion into suppressor T cells of only those T cells that underwent a limited number of cell divisions. These results are compatible with other studies that were, however, less rigorous in excluding expansion of existing cells as opposed to de novo generation of suppressor cells from naïve T cells. The fact that natural suppressor cells have an essential role in preventing autoimmunity and that they can be specifically induced by TCR agonist ligands opens new perspectives in preventing autoimmunity, transplant rejection and allergy.

Effects of oral insulin in relatives of patients with type 1 diabetes: The Diabetes Prevention Trial--Type 1

OBJECTIVE

This randomized, double-masked, placebo-controlled clinical trial tested whether oral insulin administration could delay or prevent type 1 diabetes in nondiabetic relatives at risk for diabetes.

RESEARCH DESIGN AND METHODS

We screened 103,391 first- and second-degree relatives of patients with type 1 diabetes and analyzed 97,273 samples for islet cell antibodies. A total of 3,483 were antibody positive; 2,523 underwent genetic, immunological, and metabolic staging to quantify risk of developing diabetes; 388 had a 5-year risk projection of 26-50%; and 372 (median age 10.25 years) were randomly assigned to oral insulin (7.5 mg/day) or placebo. Oral glucose tolerance tests were performed every 6 months. The median follow-up was 4.3 years, and the primary end point was diagnosis of diabetes.

RESULTS

Diabetes was diagnosed in 44 oral insulin and 53 placebo subjects. Annualized rate of diabetes was similar in both groups: 6.4% with oral insulin and 8.2% with placebo (hazard ratio 0.764, P = 0.189). In a hypothesis-generating analysis of a subgroup with insulin autoantibody (IAA) levels confirmed (on two occasions) > or =80 nU/ml (n = 263), there was the suggestion of benefit: annualized diabetes rate 6.2% with oral insulin and 10.4% with placebo (0.566, P = 0.015).

CONCLUSIONS

It is possible to identify individuals at high risk for type 1 diabetes and to enroll them in a large, multisite, randomized, controlled clinical trial. However, oral insulin did not delay or prevent type 1 diabetes. Further studies are needed to explore the potential role of oral insulin in delaying diabetes in relatives similar to those in the subgroup with higher IAA levels.

Constraints on the efficacy of mucosal tolerance in treatment of human and animal arthritic diseases

Mucosal administration of an autoantigen has been shown to be a powerful way of inducing tolerance in both animal and human arthritis clinical trials. Bovine or chicken type II collagen has been administered orally to rheumatoid arthritis patients, resulting in some, although in many cases rather limited, clinical improvement. Animal studies have revealed that the mechanisms that underlie induction of mucosal tolerance include clonal deletion, suppression of the proinflammatory Th1 cells, and the induction of regulatory T cells. These cells, defined as a persistently CD25-expressing subset of CD4(+) cells, are frequently anergic, may produce anti-inflammatory cytokines such as IL-10 and TGF-beta, and are likely to be agents of bystander suppression. A key feature that may affect the induction of these cells and other suppressive mechanisms is the dose of antigen administered. The results from human clinical trials suggest a daily dose of significantly less than 1 mg is optimal. Similarly data from collagen-induced arthritis studies reveal an optimal dose above and below which there is little or no immune suppression. Indeed, the incorrect dose can prime the immune response and aggravate disease. The timing and frequency of administration is also vital to the level of immune tolerance induced and the control of the pathological process. This and other findings derived from animal studies are discussed here in relation to the results from human clinical trials.

Antigen-specific therapies for the treatment of multiple sclerosis: a clinical trial update

Within the past year a host of antigen-specific therapies for multiple sclerosis (MS) progressed along the path from IND submission to FDA approval. The Immune Response Corporation vaccinated patients with a Vbeta6 peptide, demonstrating that the vaccine was immunogenic, well tolerated, and reduced the number of Vbeta6+ T-cells in the cerebrospinal fluid (CSF). Connetics Corp. conducted a Phase I/II trial on chronic progressive MS patients vaccinated with CDR2 peptides from TCR Vbeta55.2 and found that patients with a measurable response to the vaccine remained clinically stable for a year. A study at the University of Alberta MS Patient Care and Research Clinic demonstrated that intrathecal injection of a B cell/T cell epitope of myelin basic protein (MBP) decreased the level of antiMBP antibody, but iv. administration did not decrease the relapse rate. AutoImmune Inc. completed a Phase III trial of oral myelin in the spring of 1997 which failed to show a statistical difference between those patients fed placebo and those fed daily capsules of myelin protein (Myoral). Three phase I trials of iv. myelin antigen(s) were initiated: MP4 (Alexion Pharmaceuticals, Inc.), a recombinant fusion of myelin basic protein and proteolipid protein; AG284 (Anergen, Inc.), a solubilised HLA-DR2:MBP peptide complex; and NBI-5788 (Neurocrine Biosciences, Inc.), an altered peptide ligand of an immunodominant MBP T-cell epitope. Following the conclusion of a successful Phase III clinical trial, TEVA Pharmaceutical Industries LTD received FDA approval to market Copaxone (glatiramer acetate) for the treatment of relapsing-remitting MS in December of 1996 and launched the product in 1997. The recent preclinical research and clinical trial status of these antigen-specific MS therapeutics are summarized in this review.