A multicenter randomized controlled trial indicates that paclitaxel-coated balloons provide no benefit for arteriovenous fistulas.

The role of paclitaxel-coated balloons has been established in the coronary and peripheral arterial circulations with recent interest in the use of paclitaxel-coated balloons to improve patency rates following angioplasty of arteriovenous fistulas. To assess the efficacy of paclitaxel-coated angioplasty balloons to prolong the survival time of target lesion primary patency in arteriovenous fistulas, we designed an investigator-led multi-center randomized controlled trial with follow up time variable for a minimum of one year. Patients with an arteriovenous fistula who were undergoing an angioplasty for a clinical indication were included but patients with one or more lesions outside the treatment segment were excluded. Following successful treatment with a high-pressure balloon, 212 patients were randomized. In the intervention arm, the second component was insertion of a paclitaxel-coated balloon. In the control arm, an identical procedure was followed, but using a standard balloon. The primary endpoint was time to loss of clinically driven target lesion primary patency. Primary analysis showed no significant evidence for a difference in time to end of target lesion primary patency between groups: hazard ratio 1.18 with a 95% confidence interval of 0.78 to 1.79. There were no significant differences for any secondary outcomes, including patency outcomes and adverse events. Thus, our study demonstrated no evidence that paclitaxel-coated balloons provide benefit, following standard care high-pressure balloon angioplasty, in the treatment of arteriovenous fistulas. Hence, in view of the benefit suggested by other trials, the role of paclitaxel-coated angioplasty balloons remains uncertain.

Optimized immunosuppression to prevent graft failure in renal transplant recipients with HLA antibodies (OuTSMART): a randomised controlled trial.

Background: 3% of kidney transplant recipients return to dialysis annually upon allograft failure. Development of antibodies (Ab) against human leukocyte antigens (HLA) is a validated prognostic biomarker of allograft failure. We tested whether screening for HLA Ab, combined with an intervention to improve adherence and optimization of immunosuppression could prevent allograft failure. Methods: Prospective, open-labelled randomised biomarker-based strategy (hybrid) trial in 13 UK transplant centres [EudraCT (2012-004308-36) and ISRCTN (46157828)]. Patients were randomly allocated (1:1) to unblinded or double-blinded arms and screened every 8 months. Unblinded HLA Ab+ patients were interviewed to encourage medication adherence and had tailored optimisation of Tacrolimus, Mycophenolate mofetil and Prednisolone. The primary outcome was time to graft failure in an intention to treat analysis. The trial had 80% power to detect a hazard ratio of 0.49 in donor specific antibody (DSA)+ patients. Findings: From 11/9/13 to 27/10/16, 5519 were screened for eligibility and 2037 randomised (1028 to unblinded care and 1009 to double blinded care). We identified 198 with DSA and 818 with non-DSA. Development of DSA, but not non-DSA was predictive of graft failure. HRs for graft failure in unblinded DSA+ and non-DSA+ groups were 1.54 (95% CI: 0.72 to 3.30) and 0.97 (0.54-1.74) respectively, providing no evidence of an intervention effect. Non-inferiority for the overall unblinded versus blinded comparison was not demonstrated as the upper confidence limit of the HR for graft failure exceeded 1.4 (1.02, 95% CI: 0.72 to 1.44). The only secondary endpoint reduced in the unblinded arm was biopsy-proven rejection. Interpretation: Intervention to improve adherence and optimize immunosuppression does not delay failure of renal transplants after development of DSA. Whilst DSA predicts increased risk of allograft failure, novel interventions are needed before screening can be used to direct therapy. Funding: The National Institute for Health Research Efficacy and Mechanism Evaluation programme grant (ref 11/100/34).

Unique and cross-reactive T cell epitope peptides of the major Bahia grass pollen allergen, Pas n 1.

BACKGROUND: Bahia grass pollen (BaGP) is a major cause of allergic rhinitis. Subcutaneous allergen-specific immunotherapy is effective for grass pollen allergy, but is unsuitable for patients with moderate to severe asthma due to the risk of anaphylaxis. T cell-reactive but IgE nonreactive peptides provide a safer treatment option. This study aimed to identify and characterize dominant CD4(+) T cell epitope peptides of the major BaGP allergen, Pas n 1. METHODS: Pas n 1-specific T cell lines generated from the peripheral blood of BaGP-allergic subjects were tested for proliferative and cytokine response to overlapping 20-mer Pas n 1 peptides. Cross-reactivity to homologous peptides from Lol p 1 and Cyn d 1 of Ryegrass and Bermuda grass pollen, respectively, was assessed using Pas n 1 peptide-specific T cell clones. MHC class II restriction of Pas n 1 peptide T cell recognition was determined by HLA blocking assays and peptide IgE reactivity tested by dot blotting. RESULTS: Three Pas n 1 peptides showed dominant T cell reactivity; 15 of 18 (83%) patients responded to one or more of these peptides. T cell clones specific for dominant Pas n 1 peptides showed evidence of species-specific T cell reactivity as well as cross-reactivity with other group 1 grass pollen allergens. The dominant Pas n 1 T cell epitope peptides showed HLA binding diversity and were non-IgE reactive. CONCLUSIONS: The immunodominant T cell-reactive Pas n 1 peptides are candidates for safe immunotherapy for individuals, including those with asthma, who are allergic to Bahia and possibly other grass pollens.

Allergen-related approaches to immunotherapy.

Allergic diseases, including asthma, rhinitis and eczema, represent a major health burden worldwide. Mainstay treatments are allergen avoidance where feasible and pharmacotherapy for symptom relief. For selected patients, allergen-specific immunotherapy (SIT) offers the prospect of long lasting clinical efficacy. SIT involves the administration of allergen extract using a standardized regimen, usually subcutaneously or increasingly sublingually. However, application of this potentially curative treatment is restricted, largely due to the risk of serious adverse events, especially in asthmatics and for potent allergens such as peanut, seafood and latex. New insights into immunological mechanisms underlying effective SIT and molecular characterization of allergens and their recognition by the immune system suggest strategies for refinement of SIT. Selective targeting of allergen-specific T cells, especially regulatory T cells, is likely to be pivotal for efficacy. Recombinant allergens lacking IgE reactivity and small T cell epitope-based peptides are being trialled clinically with evidence of efficacy without serious IgE-mediated adverse reactions. Adjuvants, either co-administered or incorporated into a recombinant allergen vaccine to target tolerogenic dendritic cells may also increase efficacy. The safer sublingual route of allergen administration is attracting interest and different allergen forms may be optimal for inducing tolerance by this route. Defined allergen-derived molecules or peptides offer ease of standardization and, coupled with appropriate targeting of immunoregulatory mechanisms, will result in more widespread clinical use of SIT. Adjunct therapies such as anti-IgE antibody and corticosteroids may minimize the likelihood of adverse reactions in those with severe allergic disease who would most benefit from this treatment.

Cutting edge: Notch signaling induces a distinct cytokine profile in dendritic cells that supports T cell-mediated regulation and IL-2-dependent IL-17 production.

Recently it has been shown that dendritic cells (DC) express both Notch and Notch ligands, allowing for the possibility that Notch signaling may influence their maturation. We show that although both Jagged (Jgd) and Delta-like (DlL) ligands were able to activate the canonical Notch pathway in mouse DC, only Jgd1 could induce the production of certain cytokines. Maturation of DC via Jgd1 resulted in an entirely different maturation program from that induced through TLR (via LPS) signaling, promoting the production of high levels of IL-2 and IL-10. DC matured by Jgd1 (Jgd1-conditioned DC) promoted the survival and proliferation of CD4(+)CD25(+) regulatory T cells that were able to suppress efficiently the proliferation of CD25(-) cells. Further, CD25(+) cells cultured with Jgd1-conditioned DC produced very high levels of IL-17 in an IL-2-dependent fashion. Our data suggest a new and important role for the Notch pathway in the regulation of the DC phenotype.

House dust mite sublingual immunotherapy: the role for transforming growth factor-beta and functional regulatory T cells.

RATIONALE: Sublingual allergen-specific immunotherapy is gaining popularity for treatment of allergic diseases, but underlying immunological mechanisms are unresolved. OBJECTIVES: To perform detailed immunological investigation of sublingual house dust mite (HDM) immunotherapy. METHODS: A 12-month randomized double-blind placebo-controlled study of sublingual HDM immunotherapy in 30 HDM-allergic subjects was performed, with 1-year open extension in 9 patients on active treatment. HDM-stimulated blood mononuclear cells were analyzed for proliferation, cytokines, and regulatory T cells (Tregs) by flow cytometry and ELISA. Effects of blocking transforming growth factor (TGF)-beta and IL-10 on proliferation were determined. Treg suppressor function and allergen-specific antibody levels were measured. Clinical efficacy was assessed by symptom, medication, and Juniper quality-of-life scores. MEASUREMENTS AND MAIN RESULTS: Allergen-induced CD4(+) T-cell division and IL-5 production were significantly decreased after 6- and 12-months' active treatment but not placebo. sTGF-betaRII blocked immunotherapy-induced suppression of allergen-specific T-cell proliferation, maximal at 6 months. Decreased allergen-specific CD4(+) T-cell proliferation and increased IL-10 secretion and serum Der p 2-specific IgG(4) were maximal at 24 months' active treatment. Treg (CD4(+)CD25(+)CD127(lo)/Foxp3(+)) function was demonstrated by suppression of allergen-specific effector T-cell (CD4(+)CD25(-)CD127(hi)) proliferation and cytokine production. Clinical efficacy of immunotherapy was supported by significantly decreased rhinitis symptom score, total asthma score, and Juniper quality-of-life score. CONCLUSIONS: This study establishes the novel finding that TGF-beta mediates the immunological suppression seen early in clinically effective sublingual HDM immunotherapy in addition to an increase in Tregs with suppressor function. Clinical trial registered with www.clinicaltrials.gov (NCT00250263).

Update to the study protocol, including statistical analysis plan, for the multicentre, randomised controlled OuTSMART trial: a combined screening/treatment programme to prevent premature failure of renal transplants due to chronic rejection in patients with HLA antibodies.

BACKGROUND: Chronic rejection is the single biggest cause of premature kidney graft failure. HLA antibodies (Ab) are an established prognostic biomarker for premature graft failure so there is a need to test whether treatment decisions based on the presence of the biomarker can alter prognosis. The Optimised TacrolimuS and MMF for HLA Antibodies after Renal Transplantation (OuTSMART) trial combines two elements. Firstly, testing whether a routine screening programme for HLA Ab in all kidney transplant recipients is useful by comparing blinding versus unblinding of HLA Ab status. Secondly, for those found to be HLA Ab+, testing whether the introduction of a standard optimisation treatment protocol can reduce graft failure rates. METHODS: OuTSMART is a prospective, open-labelled, randomised biomarker-based strategy (hybrid) trial, with two arms stratified by biomarker (HLA Ab) status. The primary outcome was amended from graft failure rates at 3 years to time to graft failure to increase power and require fewer participants to be recruited. Length of follow-up subsequently is variable, with all participants followed up for at least 43 months up to a maximum of 89 months. The primary outcome will be analysed using Cox regression adjusting for stratification factors. Analyses will be according to the intention-to-treat using all participants as randomised. Outcomes will be analysed comparing standard care versus biomarker-led care groups within the HLA Ab+ participants (including those who become HLA Ab+ through re-screening) as well as between HLA-Ab-unblinded and HLA-Ab-blinded groups using all participants. DISCUSSION: Changes to the primary outcome permit recruitment of fewer participants to achieve the same statistical power. Pre-stating the statistical analysis plan guards against changes to the analysis methods at the point of analysis that might otherwise introduce bias through knowledge of the data. Any deviations from the analysis plan will be justified in the final report. TRIAL REGISTRATION: ISRCTN registry, ID: ISRCTN46157828 . Registered on 26 March 2013; EudraCT 2012-004308-36 . Registered on 10 December 2012.

Start2quit: a randomised clinical controlled trial to evaluate the effectiveness and cost-effectiveness of using personal tailored risk information and taster sessions to increase the uptake of the NHS Stop Smoking Services.

BACKGROUND: The NHS Stop Smoking Services (SSSs) offer help to smokers who want to quit. However, the proportion of smokers attending the SSSs is low and current figures show a continuing downward trend. This research addressed the problem of how to motivate more smokers to accept help to quit. OBJECTIVES: To assess the relative effectiveness, and cost-effectiveness, of an intervention consisting of proactive recruitment by a brief computer-tailored personal risk letter and an invitation to a 'Come and Try it' taster session to provide information about the SSSs, compared with a standard generic letter advertising the service, in terms of attendance at the SSSs of at least one session and validated 7-day point prevalent abstinence at the 6-month follow-up. DESIGN: Randomised controlled trial of a complex intervention with follow-up 6 months after the date of randomisation. SETTING: SSSs and general practices in England. PARTICIPANTS: All smokers aged ≥ 16 years identified from medical records in participating practices who were motivated to quit and who had not attended the SSS in the previous 12 months. Participants were randomised in the ratio 3 : 2 (intervention to control) by a computer program. INTERVENTIONS: Intervention - brief personalised and tailored letter sent from the general practitioner using information obtained from the screening questionnaire and from medical records, and an invitation to attend a taster session, run by the local SSS. Control - standard generic letter from the general practice advertising the local SSS and the therapies available, and asking the smoker to contact the service to make an appointment. MAIN OUTCOME MEASURES: (1) Proportion of people attending the first session of a 6-week course over a period of 6 months from the receipt of the invitation letter, measured by records of attendance at the SSSs; (2) 7-day point prevalent abstinence at the 6-month follow-up, validated by salivary cotinine analysis; and (3) cost-effectiveness of the intervention. RESULTS: Eighteen SSSs and 99 practices within the SSS areas participated; 4384 participants were randomised to the intervention (n = 2636) or control (n = 1748). One participant withdrew and 4383 were analysed. The proportion of people attending the first session of a SSS course was significantly higher in the intervention group than in the control group [17.4% vs. 9.0%; unadjusted odds ratio (OR) 2.12, 95% confidence interval (CI) 1.75 to 2.57; p < 0.001]. The validated 7-day point prevalent abstinence at the 6-month follow-up was significantly higher in the intervention group than in the control group (9.0% vs. 5.6%; unadjusted OR 1.68, 95% CI 1.32 to 2.15; p < 0.001), as was the validated 3-month prolonged abstinence and all other periods of abstinence measured by self-report. Using the National Institute for Health and Care Excellence decision-making threshold range of £20,000-30,000 per quality-adjusted life-year gained, the probability that the intervention was more cost-effective than the control was up to 27% at 6 months and > 86% over a lifetime horizon. LIMITATIONS: Participating SSSs may not be representative of all SSSs in England. Recruitment was low, at 4%. CONCLUSIONS: The Start2quit trial added to evidence that a proactive approach with an intensive intervention to deliver personalised risk information and offer a no-commitment introductory session can be successful in reaching more smokers and increasing the uptake of the SSS and quit rates. The intervention appears less likely to be cost-effective in the short term, but is highly likely to be cost-effective over a lifetime horizon. FUTURE WORK: Further research could assess the separate effects of these components. TRIAL REGISTRATION: Current Controlled Trials ISRCTN76561916. FUNDING DETAILS: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 3. See the NIHR Journals Library website for further project information.

Can a combined screening/treatment programme prevent premature failure of renal transplants due to chronic rejection in patients with HLA antibodies: study protocol for the multicentre randomised controlled OuTSMART trial.

BACKGROUND: Renal transplantation is the best treatment for kidney failure, in terms of length and quality of life and cost-effectiveness. However, most transplants fail after 10 to 12 years, consigning patients back onto dialysis. Damage by the immune system accounts for approximately 50% of failing transplants and it is possible to identify patients at risk by screening for the presence of antibodies against human leukocyte antigens. However, it is not clear how best to treat patients with antibodies. This trial will test a combined screening and treatment protocol in renal transplant recipients. METHODS/DESIGN: Recipients>1 year post-transplantation, aged 18 to 70 with an estimated glomerular filtration rate>30 mL/min will be randomly allocated to blinded or unblinded screening arms, before being screened for the presence of antibodies. In the unblinded arm, test results will be revealed. Those with antibodies will have biomarker-led care, consisting of a change in their anti-rejection drugs to prednisone, tacrolimus and mycophenolate mofetil. In the blinded arm, screening results will be double blinded and all recruits will remain on current therapy (standard care). In both arms, those without antibodies will be retested every 8 months for 3 years. The primary outcome is the 3-year kidney failure rate for the antibody-positive recruits, as measured by initiation of long-term dialysis or re-transplantation, predicted to be approximately 20% in the standard care group but <10% in biomarker-led care. The secondary outcomes include the rate of transplant dysfunction, incidence of infection, cancer and diabetes mellitus, an analysis of adherence with medication and a health economic analysis of the combined screening and treatment protocol. Blood samples will be collected and stored every 4 months and will form the basis of separately funded studies to identify new biomarkers associated with the outcomes. DISCUSSION: We have evidence that the biomarker-led care regime will be effective at preventing graft dysfunction and expect this to feed through to graft survival. This trial will confirm the benefit of routine screening and lead to a greater understanding of how to keep kidney transplants working longer. TRIAL REGISTRATION: Current Controlled Trials ISRCTN46157828.

T cell targeted strategies for improved efficacy and safety of specific immunotherapy for allergic disease.

Allergic diseases including asthma, rhinitis and eczema are known to be a major health and economic burden worldwide. Specific immunotherapy (SIT) is potentially curative but restricted in use, e.g. for asthmatics, due to risk of serious adverse events. Safer, effective SIT preparations require elucidation of mechanisms and immunoregulatory factors. Allergen-specific T cells play a pivotal role. For allergic individuals, allergen-stimulated T cells largely secrete IL-4, IL-5 and IL-13 (Th2-type cytokines), whereas non-allergics show predominant IFN-γ secretion (Th1-type). Clinically successful SIT is accompanied by altered allergen-specific T cell response, with decreased Th2/Th1 ratio, enhanced IL-10 secretion and regulatory T cell induction. Contributing factors include allergen concentration and form, adjuvant and antigen presenting cell type. In conventional SIT, high dose unfractionated allergen extracts are injected incrementally via the subcutaneous route. To avoid adverse IgE-mediated events but retain efficacy, hypoallergenic T cell-reactive allergen derivatives can be used. These include peptides containing dominant T cell epitopes of allergens, chemically-modified allergens, and recombinant whole or mutant allergens. Such approaches have been evaluated successfully in animal models and early phase clinical trials. Adjuvants and carriers including bacterial and viral components, liposomes and DNA vaccines also promote repolarisation of T cell response and regulatory T cell induction. However caution is needed as excessive IFN- γ secretion may invoke pathogenic inflammation. Sublingual administration has fewer adverse events and is gaining popularity for respiratory allergens, and other routes including intranasal and oral are under evaluation. T cell targeted strategies will facilitate wider clinical application of SIT and reliable laboratory assays for monitoring treatment.

Functional regulatory T cells and allergen immunotherapy.

PURPOSE OF REVIEW: Burgeoning literature ascribing roles for regulatory T cells (Treg) in controlling clinical allergy frequently relies on phenotypic markers rather than functional suppression assays. This review examines evidence for functional Treg in controlling immune responses to allergen with particular focus on allergen-specific immunotherapy. RECENT FINDINGS: Over the last year, use of recently identified Treg markers has facilitated more precise delineation and isolation of Treg subtypes. Advanced flow cytometry allows better discrimination and tracking of effector T cells (Teff) and Treg in co-culture assays for Treg function. These approaches enable critical appraisal of the evidence for Treg mediation of the observed changes in immune reactivity to allergen accompanying immunotherapy. Recent studies suggest that different mechanisms of immune regulation may occur at different times of immunotherapy, with Treg playing a more important role early in treatment. Additionally, advanced imaging techniques reveal increased Treg numbers in allergen-exposed mucosal tissue after therapy consistent with an enhanced local functional role. SUMMARY: These findings support a mechanistic role for Treg early in allergen immunotherapy. Research is required to clarify the precise Treg subsets involved, their specificity and how their activity can be enhanced during immunotherapy by appropriate allergen form, optimal site of administration and use of adjuvants and adjunct therapies.

Secretion of IFN-gamma and not IL-2 by anergic human T cells correlates with assembly of an immature immune synapse.

We report differences in the supramolecular organization of the immunologic synapse (IS) formed by resting and anergic human T cells with agonist peptide-loaded antigen-presenting cells (APCs). T cells reactive to influenza A hemagglutinin peptide or Fel d 1 peptide 4 were rendered both anergic and regulatory by incubation with high doses of agonist peptide in the absence of APCs. At the IS between resting T cells and peptide-loaded APCs, both CD3epsilon and CD3zeta initially accumulate within a ring or arc before redistributing within 30 minutes to single or multiple foci more central to the contact. In contrast, at synapses formed by anergized T cells, CD3epsilon and CD3zeta remained organized within an arc or ring and failed to redistribute centrally. However, intercellular communication between anergic human T cells and agonist peptide-loaded APCs was not a null event, since it triggered secretion of T-cell interferon gamma (IFN-gamma) but not, for example, interleukin 2 (IL-2). Thus, distinct organizations of CD3 at the T-cell IS correlate with different cytokine profiles; the mature IS formed by resting T cells correlates with their production of both IFN-gamma and IL-2, whereas the immature IS formed by anergic T cells seems able to facilitate IFN-gamma but not IL-2 production.

High dose allergen stimulation of T cells from house dust mite-allergic subjects induces expansion of IFN-gamma+ T Cells, apoptosis of CD4+IL-4+ T cells and T cell anergy.

BACKGROUND: During clinically effective allergen-specific immunotherapy a shift in cytokine dominance from IL-4, IL-5 predominant to IFN-gamma predominant has been observed. As antigen concentration influences Th cell priming, this study aimed to determine the effect of different allergen concentrations on human house dust mite (HDM)-specific T cell production of IL-4 and IFN-gamma, proliferation and apoptosis. METHODS: HDM-allergic donor PBMC were cultured for 14 days with different concentrations of HDM extract (1, 10 and 100 microg/ml). T cell intracellular IL-4 and IFN-gamma, division (CFSE labelling) and apoptosis (active caspase-3 staining) were analysed by flow cytometry. Proliferation was assessed by (3)H-thymidine incorporation. RESULTS: Increased CD4+IFN-gamma+ and CD8+IFN-gamma+ T cell numbers were observed in high allergen concentration cultures compared with low concentration cultures whereas there were no differences in CD4+IL-4+ and CD8+IL-4+ T cell numbers. CFSE cell labelling revealed that high allergen concentration favours the expansion of IFN-gamma-producing CD4+ T cells. The proportion of apoptotic cells increased with allergen concentration and there was preferential apoptosis of CD4+IL-4+ T cells. HDM-induced proliferation was decreased in high allergen concentration cultures; this was reversible by IL-2 consistent with anergy. CONCLUSION: These results show that T cell division and apoptosis contribute to the cytokine skewing to predominant IFN-gamma production by T cells observed at high allergen concentration. Thus the use of hypoallergenic T cell reactive preparations which can be given safely at higher doses than natural extracts may enhance efficacy of allergen-specific immunotherapy.