Oligoclonal analysis of the atopic T cell response to the group 1 allergen of Cynodon dactylon (bermuda grass) pollen: pre- and post-allergen-specific immunotherapy

BACKGROUND: Bermuda grass pollen (BGP) is an increasingly important seasonal aeroallergen in Australia and other subtropical and temperate regions. BGP shares minimal allergenic cross-reactivity with pollens of rye grass or other Pooideae grasses often used for desensitization regimens in grass pollen allergy. Current allergen immunotherapy is seldom used in asthmatic patients due to IgE-mediated side effects. Since clinically effective immunotherapy is linked with altered allergen-specific T cell response, characterisation of human T cell reactivity to Cyn d 1, the major B cell allergen of BGP, should permit the design of effective and safe immunotherapy for BGP allergy. METHODS: Short-term BGP-specific CD4+ T cell lines were established from peripheral blood of 14 BGP-sensitive patients before and after conventional 50% BGP and 50% 7-grass mix subcutaneous specific allergen immunotherapy (SIT). T cell diversity of antigen specificity and function was assessed by proliferation and cytokine production to BGP, Cyn d 1 and Cyn d 1 peptides. RESULTS: Three highly immunogenic regions of Cyn d 1 were identified in 13/14 patients pre-SIT: Cyn d 1 (109-128), (181-209) and (217-241). The SIT regimen was clinically efficacious. Following SIT, decreased proliferation to BGP, Cyn d 1 and Cyn d 1 peptides was observed with a marked decrease in the IL-5:IFN-gamma ratio. CONCLUSIONS: Cyn d 1 is a major T cell allergen of BGP. Decreased Cyn d 1-specific IL-5 dominant T cell responses were observed in association with clinically effective treatment with the 50% BGP and 50% 7-grass mix. Identified dominant T cell regions of Cyn d 1 should facilitate safer vaccine development for BGP-induced asthma in addition to rhinitis.     

Bacteremia due to Rhodococcus equi--a case report

Rhodococcus equi (R. equi) primarily causes zoonotic infections affecting grazing animals and is an unusual cause of infection in immunocompetent human beings. We report a case of bacteremia due to R. equi a rare isolate in a child suffering from protein energy malnutrition     

A potent analog of 1alpha,25-dihydroxyvitamin D3 selectively induces bone formation

1,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] is a principal regulator of calcium and phosphorus homeostasis through actions on intestine, kidney, and bone. 1,25(OH)(2)D(3) is not considered to play a significant role in bone formation, except for its role in supporting mineralization. We report here on the properties of 2-methylene-19-nor-(20S)-1alpha,25(OH)(2)D(3) (2MD), a highly potent analog of 1,25(OH)(2)D(3) that induces bone formation both in vitro and in vivo. Selectivity for bone was first demonstrated through the observation that 2MD is at least 30-fold more effective than 1,25(OH)(2)D(3) in stimulating osteoblast-mediated bone calcium mobilization while being only slightly more potent in supporting intestinal calcium transport. 2MD is also highly potent in promoting osteoblast-mediated osteoclast formation in vitro, a process essential to both bone resorption and formation. Most significantly, 2MD at concentrations as low as 10(-12) M causes primary cultures of osteoblasts to produce bone in vitro. This effect is not found with 1,25(OH)(2)D(3) even at 10(-8) M, suggesting that 2MD might be osteogenic in vivo. Indeed, 2MD (7 pmol/day) causes a substantial increase (9%) in total body bone mass in ovariectomized rats over a 23-week period. 1,25(OH)(2)D(3) (500 pmol three times a week) only prevented the bone loss associated with ovariectomy and did not increase bone mass. These results indicate that 2MD is a potent bone-selective analog of 1,25(OH)(2)D(3) potentially effective in treating bone loss diseases.     

TLR ligands of ryegrass pollen microbial contaminants enhance Th1 and Th2 responses and decrease induction of Foxp3hi regulatory T cells

Microbial contamination of grass pollens could affect sensitization, subsequent allergic response, and efficacy of allergen‐specific immunotherapy. We investigated whether bacterial immunomodulatory substances can direct PBMC responses of allergic and nonatopic subjects against ryegrass pollen (RGP) toward Th1, Th2, or regulatory T (Treg) cells. Aqueous extracts of RGP with high or low LPS were fractionated into large and small molecular weight (MW) components by diafiltration. CFSE‐labeled PBMCs from allergic and nonatopic subjects were stimulated with RGP extracts (RGPEs) and analyzed for cytokine secretion and T‐cell responses. High LPS RGPE increased IFN‐γ⁺ Th1 and IL‐4⁺ Th2 effector cell induction and consistently decreased CD4⁺Foxp3^hi Treg‐cell induction. IL‐10‐producing T‐cell frequency was unaltered, but IL‐10 secretion was increased by high LPS RGPE. RGPE‐stimulation of TLR‐transfected cell lines revealed that high LPS pollen also contained a TLR2‐ligand, and both batches a TLR9‐ligand. Beta‐1,3‐glucans were detected in large and small MW fractions and were also T‐cell stimulatory. In conclusion, coexposure to allergen and proinflammatory microbial stimuli does not convert an established Th2‐ into a Th1‐response. Instead, proinflammatory responses are exacerbated and Foxp3^hi Treg‐cell induction is decreased. These findings show that adjuvants for specific immunotherapy should enhance Treg cells rather than target immune deviation from Th2 to Th1.     

Advances in allergen-specific immune cell measurements for improved detection of allergic sensitization and immunotherapy responses

Over the past two decades, precision medicine has advanced diagnostics and treatment of allergic diseases. Component-resolved analysis of allergen sensitization facilitates stratification of patients. Furthermore, new formulations of allergen immunotherapy (AIT) products can more effectively deliver the relevant components. Molecular insights from the identification of allergen component sensitization and clinical outcomes of treatment with new AIT formulations can now be utilized for a deeper understanding of the nature of the pathogenic immune response in allergy and how this can be corrected by AIT. Fundamental in these processes are the allergen-specific B and T cells. Within the large B- and T-cell compartments, only those that specifically recognize the allergen with their immunoglobulin (Ig) or T-cell receptor (TCR), respectively, are of clinical relevance. With peripheral blood allergen-specific B- and T-cell frequencies below 1%, bulk cell analysis is typically insufficiently sensitive. We here review the latest technologies to detect allergen-specific B and T cells, as well as new developments in utilizing these tools for diagnostics and therapy monitoring to advance precision medicine for allergic diseases.     

IL-5 promotes induction of antigen-specific CD4+CD25+ T regulatory cells that suppress autoimmunity

Immune responses to foreign and self-Ags can be controlled by regulatory T cells (Tregs) expressing CD4 and IL-2Rα chain (CD25). Defects in Tregs lead to autoimmunity, whereas induction of Ag-specific CD4+CD25+ Tregs restores tolerance. Ag-specific CD4+CD25+ FOXP3+Tregs activated by the T helper type 2 (Th2) cytokine, IL-4, and specific alloantigen promote allograft tolerance. These Tregs expressed the specific IL-5Rα and in the presence of IL-5 proliferate to specific but not third-party Ag. These findings suggest that recombinant IL-5 (rIL-5) therapy may promote Ag-specific Tregs to mediate tolerance. This study showed normal CD4+CD25+ Tregs cultured with IL-4 and an autoantigen expressed Il-5rα. Treatment of experimental autoimmune neuritis with rIL-5 markedly reduced clinical paralysis, weight loss, demyelination, and infiltration of CD4+ (Th1 and Th17) CD8+ T cells and macrophages in nerves. Clinical improvement was associated with expansion of CD4+CD25+FOXP3+ Tregs that expressed Il-5rα and proliferated only to specific autoantigen that was enhanced by rIL-5. Depletion of CD25+ Tregs or blocking of IL-4 abolished the benefits of rIL-5. Thus, rIL-5 promoted Ag-specific Tregs, activated by autoantigen and IL-4, to control autoimmunity. These findings may explain how Th2 responses, especially to parasitic infestation, induce immune tolerance. rIL-5 therapy may be able to induce Ag-specific tolerance in autoimmunity.     

Discovery and Development of Potent and Selective Inhibitors of Histone Methyltransferase G9a

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