The immune tolerance network: a new paradigm for developing tolerance-inducing therapies

Immune tolerance therapies are designed to reprogram immune cells in a highly specific fashion to eliminate pathogenic responses while preserving protective immunity. A concept that has tantalized immunologists for decades, the development of tolerance-inducing therapies, would revolutionize the management of a wide range of chronic and often debilitating diseases by obviating the need for lifelong immunosuppressive regimens. The advances of the past decade have provided a more detailed understanding of the molecular events associated with T-cell recognition and activation. Building on these advances, immunologists have demonstrated the feasibility of various tolerance-inducing approaches in small- and large-animal models of autoimmunity, allergy, and transplant graft rejection. Unprecedented opportunities to test these approaches in a variety of human diseases have now emerged. To capitalize on these advances, the National Institutes of Health recently established the Immune Tolerance Network (ITN), an international consortium of more than 70 basic and clinical immunologists dedicated to the evaluation of novel tolerance-inducing therapies and associated studies of immunologic mechanisms. By using a unique interactive approach to accelerate the development of clinical tolerance therapies, the ITN is partnering with the biotechnology and pharmaceutical industries to examine innovative tolerogenic approaches in a range of allergic and autoimmune diseases and to prevent graft rejection after transplantation. Two years since its inception, the ITN now has approximately 2 dozen clinical trials or tolerance assays studies ongoing or in later stages of protocol development. This report summarizes the rationale for emphasizing clinical research on immune tolerance and highlights the progress of the ITN.     

Lactoferrin in aspirates of odontogenic cyst fluid.

The possibility that the presence of lactoferrin in aspirates of odontogenic cyst fluid might be a useful preoperative diagnostic marker for odontogenic keratocyst was investigated. Using qualitative and quantitative immunodiffusion methods fluid from 29 of 29 dental (radicular) cysts, 12 of 14 dentigerous cysts and 27 of 31 keratocysts were found to contain lactoferrin. Although some of the highest concentrations of lactoferrin were detected in fluids from keratocysts, there was no significant difference between lactoferrin concentrations among the three groups. Neutrophil elastase was detected in 20 of 24 samples tested, 22 of which also contained lactoferrin. Immunocytochemical localisation of both lactoferrin and elastase was confined to neutrophils infiltrating cyst walls. These results suggest that lactoferrin in fluid from odontogenic cysts is derived from infiltrating neutrophils and that its presence in aspirated fluids is not a useful diagnostic marker for odontogenic keratocyst.     

Comprehensive family practice clerkship in a minority institution

A comprehensive family practice clerkship program at Howard University College of Medicine has been conducted since 1970. This institution is one of three predominantly black institutions offering a family practice program. The senior clerkship is mandatory and at least 20 to 25 percent of each class elect to participate in a four-to six- week family practice preceptorship. As a result of the clerkship''s success, over 50 percent of the program''s graduates actively practice in primary medical manpower shortage or medically underserved areas.     

Differentiation of Streptococcus uberis from Streptococcus parauberis by polymerase chain reaction and restriction fragment length polymorphism analysis of 16S ribosomal DNA.

Streptococcus uberis type II has been proposed recently as a separate species designated Streptococcus parauberis (A. M. Williams and M. D. Collins, J. Appl. Bacteriol. 68:485-490, 1990). Differentiation of S. parauberis from S. uberis has been possible only by DNA-DNA hybridization or 16S rRNA sequencing, since the biochemical and serological characteristics of the two species are indistinguishable. A simple and reliable technique was developed for differentiating S. parauberis (S. uberis type II [ATCC 13386]) from S. uberis (S. uberis type I [ATCC 9927, ATCC 13387, and ATCC 27958]) by restriction fragment length polymorphism (RFLP) analysis of 1.4-kb 16S ribosomal DNA (rDNA). Oligonucleotide primers complementary to 16S rRNA genes were used to amplify 16S ribosomal gene fragments from genomic DNA by polymerase chain reaction. The 1.4-kb 16S rDNA fragment was digested with ScaI, NspI, DdeI, and AvaII restriction endonucleases. Restriction fragments produced by all four restriction endonucleases were characteristic for each species. RFLP analysis of 16S rDNA from 24 "S. uberis" isolates obtained from mammary secretions of dairy cows indicated that all 24 isolates were indeed S. uberis.     

Inhibition of axoplasmic transport in the developing visual system of the rat—I. Structural changes in the retina and optic nerve with graded doses of intraocular colchicine

In order to study the role of axonal transport in the mediation of transneuronal metabolic stimulation upon a population of differentiating neurons, colchicine, a potent inhibitor of rapid and slow phases of axonal transport, was injected into the eye of albino rats at 1,3,5, 10, 15 and 20 days postnatal in concentrations ranging from 10^?5 M to 2 × 10²M and in quantities of 0.3 to 0.5μl. Quantitative light and electron microscopy were subsequently employed to assess reactive alterations in the developing retina and optic nerve. Application of colchicine severely retarded the development of the sensory elements, with disappearance of synaptic ribbons of sensory cell axons, a significant reduction in the thickness of the inner plexiform layer, due to the presence of numerous shrunken synaptic elements and the appearance of rosettes of sensory cells displaced to the inner nuclear layer. These alterations were found to be dose-dependent. Counts of ganglion cell populations at various times after application of colchicine demonstrated optimal concentrations which could be injected at each postnatal age without causing ganglion cell degeneration. Ultrastructural examination of such cells revealed varying degrees of disorganization and dissolution of the endoplasmic reticulum with the formation of occasional small cytoplasmic vacuoles. Higher concentrations of colchicine caused extensive vacuole formation in all classes of retinal neurons, scattered hyperchromic cells and widespread degeneration and autolysis.The diameter of the optic nerve was reduced to 60–95% of normal following intraocular colchicine. depending on the concentration employed, but electron microscopy revealed normal patterns of distribution of axoplasmic microtubules and filaments in control and experimental animals and quantitative analysis revealed no significant loss of axons. While no reactive changes took place in individual elements, the periphery of the nerve was often indented by a highly-folded glia limitans.Maximal doses of intraocular colchicine for each age level were established by this study. These were: 1 day, 10^?3 M: 5 days, 5 × 10^?3M; 10 days, 5 × 10^?3M; 15 and 20 days, 10^?2 M. The information derived from this morphological analysis provides the foundation for subsequent measurements of axonal transport inhibition in the developing visual system to be reported in the second article of this series.     

Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization

The development and application of fluorescence in-situ hybridization (FISH) has opened the way for comprehensive studies on numerical chromosome abnormalities in human spermatozoa. FISH can be rapidly applied to large numbers of spermatozoa and thus overcomes the major limitation of karyotyping spermatozoa after penetration of zona-free hamster oocytes. The simultaneous hybridization of two or more chromosome-specific probes to spermatozoa and subsequent detection of the bound probes using different fluorescent detection systems enables two or more chromosomes to be localized simultaneously in the same spermatozoon and provides a technique for undertaking reasonable estimates of aneuploidy. The most commonly used probes are those which bind to the centromeric region of specific chromosomes. Most studies to date have concentrated on estimating aneuploidy in spermatozoa from normospermic men, although reports are beginning to appear on aneuploidy in spermatozoa from subfertile and infertile men. Multi- probe FISH studies have generally reported disomy (hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary evidence that some chromosomes such as X, Y and 21 are predisposed towards higher rates of non-disjunction during spermatogenesis. There are also suggestions of inter-donor variability in aneuploidy frequencies for specific chromosomes, although this requires confirmation in larger studies. While FISH is clearly a powerful technique that has many applications in reproductive medicine, it must also be realized that it does have limitations and the technology itself is still evolving and has yet to be fully validated on spermatozoa.      

Depression among patients with a chief complaint of chronic fatigue

The prevalence of mood disorders among patients with chronic fatigue was examined in a group of 100 adults who had experienced fatigue symptoms for an average of 13 years. Patients received a comprehensive history, physical and laboratory evaluation and completed the National Institute of Mental Health Diagnostic Interview Schedule and the Beck Depression Inventory (BDI). Among 44 patients with depressive illness, the onset of their first depressive episode was strongly associated with and preceded the onset of chronic fatigue. The BDI, fatigue history, demographic factors, and findings from the physical examination and laboratory had only modest success in discriminating those patients with depressive illness from other patients. We conclude that depressive illness is an important precursor of chronic fatigue.     

The relationship between epithelial Ia expression and the inflammatory cell infiltrate during experimental oral carcinogenesis

Summary The development of oral epithelial expression of Ia antigens and its relationship to the presence of IL-2r⁺ (CD25⁺) cells was investigated in rats treated with the water soluble carcinogen 4-nitroquinoline-N-oxide (4NQO). Acetone fixed frozen sections of the palate and tongue were stained using an indirect immunoperoxidase technique and monoclonal antibodies to rat Ia (I-A & I-E) and IL-2 receptor. After 4 weeks 4NQO treatment all rats expressed oral epithelial Ia but thereafter (2–9 months) expression was present in only 20–40% of animals. Epithelial expression of Ia by histologically normal, dysplastic and neoplastic epithelium was always associated with the presence of an underlying inflammatory cell infiltrate containing CD25⁺ cells. Overall there were significantly more CD25⁺ cells in tissue specimens containing Ia⁺ epithelium compared with Ia^– epithelium. Furthermore, during the first 4 weeks of carcinogen treatment, a significant positive correlation was found between the CD25⁺ cell density and occurrence of focal epithelial Ia expression. These results, together with analysis of the T cell, NK cell, macrophage and B cell content of the infiltrates induced by 4NQO, suggest that the CD25⁺ cells represent activated T cells. Thus, our results in this experimental model are consistent with the idea that epithelial expression of Ia is the result of production of IFN- by locally activated T cells.     

Epicutaneous immunotherapy protects cashew-sensitized mice from anaphylaxis

Background

The prevalence of tree nut allergy has increased worldwide, and cashew has become one of the most common food allergens. More critically, cashew allergy is frequently associated with severe anaphylaxis. Despite the high medical need, no approved treatment is available and strict avoidance and preparedness for prompt treatment of allergic reactions are considered dual standard of care. In the meantime, Phase III study results suggest investigational epicutaneous immunotherapy (EPIT) may be a relevant and safe treatment for peanut allergy and may improve the quality of life for many peanut allergic children.

Objective

We aimed to evaluate the capacity of EPIT to provide protection against cashew-induced anaphylaxis in a relevant mouse model.

Methods

The efficacy of EPIT was evaluated by applying patches containing cashew allergens to cashew-sensitized mice. As negative control, sham mice received patches containing excipient. Following treatment, mice were challenged orally to cashew and anaphylactic symptoms, as well as plasmatic levels of mast-cell proteases (mMCP)-1/7, were quantified.

Results

Of 16 weeks of EPIT significantly protects against anaphylaxis by promoting a faster recovery of challenged mice. This protection was characterized by a significant reduction of temperature drop and clinical symptoms, 60 minutes after challenge. This was associated with a decrease in mast-cell reactivity as attested by the reduction of mMCP-1/7 in plasma, suggesting that EPIT specifically decrease IgE-mediated anaphylaxis.

Conclusion

We demonstrate that EPIT markedly reduced IgE-mediated allergic reactions in a mouse model of cashew allergy, which suggests that EPIT may be a relevant approach to treating cashew allergy.