Which allergen extract for grass pollen immunotherapy? An in vitro study

Green Roof Gardens - Selecting Allergy-Friendly Vegetation: A Global Allergy and Asthma Excellence Network (GA²LEN) Position Paper

Green roof gardens are important for planetary health by mitigating the effects of urbanization. Because of the nature of green roof gardens, only particular plants can be used. The allergologic impact of these plants remains ill-characterized and guidance on building allergy-friendly green roof gardens is missing. To address this gap, we investigated the plant spectrum of several German green roof companies and categorized plants based on their primary pollination mechanism. Except for grasses, most plants were insect-pollinated and of low allergenicity. In addition, we conducted a review on the allergologic impact of plants used for green roof gardens. Our aim was to provide landscape architects with guidance on how to develop allergy-friendly green roof gardens. We highlight the need for universally accepted standards for assessing the allergenicity of roof top plants. Also, we recommend the joint development, by green roof producers and allergists, of criteria for allergy-friendly roof gardens. Their implementation may help to reduce the risk of allergen sensitization and allergy exacerbation, such as by avoiding the use of wind-pollinated plants of proven allergenicity including grasses. Green infrastructure, such as green roofs, should benefit planetary health without increasing the prevalence and burden of allergies.

A survey on the perception of allergy specialists about the reimbursed grass pollen tablets for seasonal allergic rhinitis in Italy

Background

Sublingual immunotherapy (SLIT) is a feasible option to classical subcutaneous immunotherapy to treat respiratory allergy and is increasingly prescribed in Europe. However, the lack of reimbursement may limit its prescription. In 2015, the 5-grass pollen tablets was authorized by the European Medicine Agency to treat grass-pollen induced rhinitis and was approved in Italy for full reimbursement. We evaluated the opinions of allergy specialists after the availability of the reimbursed 5-grass pollen tablets.

Methods

A multiple choice questionnaire composed by six questions was used to assess the specialists opinion. The questionnaire was uploaded on the free access online platform SurveyMonkey. The link to access the platform was sent to all members of the Società Italiana di Asma, Allergologia e Immunologia Clinica (SIAAIC). The access to the questionnaire was anonymous. At survey ending, the access was closed and data were downloaded directly from SurveyMonkey website.

Results

The questionnaire was filled by 70 allergists. The majority of allergists felt as most important the concept of SLIT as a drug, the content of allergen extract mirroring the natural exposure, the pre-coseasonal schedule as the most patient’s oriented, the very good profile of tolerability and safety, the importance of the build-up phase, and the importance of checking the patient after starting immunotherapy.

Conclusions

The opinions of the Italian allergy specialists about the reimbursed 5-grass-pollen tablets are very positive and make likely an appropriate prescription of SLIT for grass-pollen induced rhinitis in the next years.

T-cell epitope conservation across allergen species is a major determinant of immunogenicity

BACKGROUND

Patients with pollen allergies are frequently polysensitized. Pollens contain epitopes that are conserved across multiple species.

OBJECTIVE

We sought to demonstrate that cross-reactive T cells that recognize conserved epitopes show higher levels of expansion than T cells recognizing monospecific epitopes because of more frequent stimulation.

METHOD

RNA was sequenced from 9 pollens, and the reads were assembled de novo into more than 50,000 transcripts. T-cell epitopes from timothy grass (Phleum pratense) were examined for conservation in these transcripts, and this was correlated to their ability to induce T-cell responses. T cells were expanded in vitro with P pratense-derived peptides and tested for cross-reactivity to pollen extracts in ELISpot assays.

RESULTS

We found that antigenic proteins are more conserved than nonimmunogenic proteins in P pratense pollen. Additionally, P pratense epitopes that were highly conserved across pollens elicited more T-cell responses in donors with grass allergy than less conserved epitopes. Moreover, conservation of a P pratense peptide at the transcriptomic level correlated with the ability of that peptide to trigger T cells that were cross-reactive with other non-P pratense pollen extracts.

CONCLUSION

We found a correlation between conservation of peptides in plant pollens and their T-cell immunogenicity within P pratense, as well as their ability to induce cross-reactive T-cell responses. T cells recognizing conserved epitopes might be more prominent because they can be stimulated by a broader range of pollens and thereby drive polysensitization in allergic donors. We propose that conserved peptides could potentially be used in diagnostic or immunomodulatory approaches that address the issue of polysensitization and target multiple pollen allergies.

Grass-specific CD4(+) T-cells exhibit varying degrees of cross-reactivity, implications for allergen-specific immunotherapy

BACKGROUND

Conceptually, allergic responses may involve cross-reactivity by antibodies or T-cells. While IgE cross-reactivity among grass-pollen allergens has been observed, cross-reactivity at the allergen-specific T-cell level has been less documented. Identification of the patterns of cross-reactivity may improve our understanding, allowing optimization of better immunotherapy strategies.

OBJECTIVES

We use Phleum pratense as model for the studying of cross-reactivity at the allergen-specific CD4(+) T cell level among DR04:01 restricted Pooideae grass-pollen T-cell epitopes.

METHODS

After in vitro culture of blood mono-nucleated cells from grass-pollen-allergic subjects with specific Pooideae antigenic epitopes, dual tetramer staining with APC-labelled DR04:01/Phleum pratense tetramers and PE-labelled DR04:01/Pooideae grass homolog tetramers was assessed to identify cross-reactivity among allergen-specific DR04:01-restricted T-cells in six subjects. Direct ex vivo staining enabled the comparison of frequency and phenotype of different Pooideae grass-pollen reactive T-cells. Intracellular cytokine staining (ICS) assays were also used to examine phenotypes of these T-cells.

RESULTS

T-cells with various degrees of cross-reactive profiles could be detected. Poa p 1 97-116 , Lol p 1 221-240 , Lol p 5a 199-218 , and Poa p 5a 199-218 were identified as minimally cross-reactive T-cell epitopes that do not show cross-reactivity to Phl p 1 and Phl p 5a epitopes. Ex vivo tetramer staining assays demonstrated T-cells that recognized these minimally cross-reactive T-cell epitopes are present in Grass-pollen-allergic subjects.

CONCLUSIONS

Our results suggest that not all Pooideae grass epitopes with sequence homology are cross-reactive. Non-cross-reactive T-cells with comparable frequency, phenotype and functionality to Phl p-specific T-cells suggest that a multiple allergen system should be considered for immunotherapy instead of a mono-allergen system.

Multiple grass mixes as opposed to single grasses for allergen immunotherapy in allergic rhinitis

Grass pollen allergy affects approximately 40% of allergic patients. Subcutaneous allergen immunotherapy (SCIT) is the only allergen-specific and disease-modifying treatment available. Currently available therapeutic vaccines for the treatment of grass pollen allergy are based on natural grass pollen extracts which are either made from pollen of one cross-reactive grass species or from several related grass species. Clinical studies have shown that SCIT performed with timothy grass pollen extract is effective for the treatment of grass pollen allergy. Moreover, it has been demonstrated that recombinant timothy grass pollen allergens contain the majority of relevant epitopes and can be used for SCIT in clinical trials. However, recent in vitro studies have suggested that mixes consisting of allergen extracts from several related grass species may have advantages for SCIT over single allergen extracts. Here, we review current knowledge regarding the disease-relevant allergens in grass pollen allergy, available clinical studies comparing SCIT with allergen extracts from timothy grass or from mixes of several related grass species of the Pooideae subfamily, in vitro cross-reactivity studies performed with natural allergen extracts and recombinant allergens and SCIT studies performed with recombinant timothy grass pollen allergens. In vitro and clinical studies performed with natural allergen extracts reveal no relevant advantages of using multiple grass mixes as opposed to single grass pollen extracts. Several studies analysing the molecular composition of natural allergen extracts and the molecular profile of patients' immune responses after SCIT with allergen extracts indicate that the major limitation for the production of a high quality grass pollen vaccine resides in intrinsic features of natural allergen extracts which can only be overcome with recombinant allergen-based technologies.

5-grass pollen tablets achieve disease control in patients with seasonal allergic rhinitis unresponsive to drugs: a real-life study

Background

An important subpopulation in allergic rhinitis is represented by patients with severe form of disease that is not responsive to drug treatment. It has been reported that grass pollen subcutaneous immunotherapy is effective in drug-resistant patients. In a real-life study, we evaluated the efficacy of 5-grass pollen tablets in patients with grass pollen-induced allergic rhinitis not responsive to drug therapy.

Methods

We carried out this multicenter observational study in adults and adolescents with grass-induced allergic rhinitis not responsive to drug therapy who were treated for a year with 5-grass pollen tablets. Clinical data collected before and after sublingual immunotherapy (SLIT) included Allergic Rhinitis and its Impact on Asthma (ARIA) classification of allergic rhinitis, response to therapy, and patient satisfaction.

Results

Forty-seven patients entered the study. By ARIA classification, three patients had moderate to severe intermittent allergic rhinitis, ten had mild persistent allergic rhinitis, and 34 had moderate to severe persistent allergic rhinitis. There were no cases of mild intermittent allergic rhinitis before SLIT. After SLIT, 33 patients had mild intermittent allergic rhinitis, none had moderate to severe intermittent allergic rhinitis, seven had mild persistent allergic rhinitis, and seven had moderate to severe persistent allergic rhinitis. The mean medication score decreased from 4.2±1.3 before to 2.4±2.0 after SLIT (P<0.01), representing a reduction of 42%. The response to treatment before SLIT was judged as poor by 70% of patients and very poor by 30%. Patient satisfaction was significantly increased after SLIT (P<0.01).

Conclusion

In real life, most patients with grass pollen-induced allergic rhinitis not responsive to drug treatment can achieve control of the condition with one season of treatment using 5-grass pollen tablets.

Economic evaluation of 5-grass pollen tablets versus placebo in the treatment of allergic rhinitis in adults

Background

Allergen immunotherapy (AIT) is aimed at modifying the immune response to a causative allergen, thereby reducing clinical symptoms and symptomatic medication intake and improving quality of life. Long-term AIT research has led to the development of 5-grass pollen tablets, currently indicated for the treatment of grass pollen-induced allergic rhinitis (AR).

Methods

A post-hoc analysis was conducted using the Average Adjusted Symptom Score (AAdSS) to compare the effect of treatment of AR with 5-grass pollen tablets versus placebo treatment. Using the results of the VO34.04 and VO53.06 trials and economic data, cost-effectiveness analysis of 5-grass pollen tablet treatment was performed from the Italian third-party payer perspective with cost data derived from a study of 2008 updated to 2011. Also a societal perspective was considered by using the costs related to the losses of productivity by following the human capital approach. Using the results of the analysis, the estimated receiver-operating characteristic curve was plotted to evaluate medication effectiveness in terms of quality-adjusted life years (QALYs) and a decision tree constructed to model the possible outcomes and costs for adults and paediatric patients with a low, medium, and high AAdSS. Finally, probabilistic sensitivity analysis was conducted to test the robustness of the results as well as their consistency at an assumed cost-effectiveness threshold of € 30,000/QALY.

Results

The results indicate that compared to the placebo, the 5-grass pollen tablet treatment provides a benefit of 0.127 QALYs in medium AAdSS patients and of 0.143 QALYs in high AAdSS patients. The 5-grass pollen tablet treatment was found to cost € 1,024/QALY for patients with a medium AAdSS and € 1,035/QALY for patients with a high AAdSS. Of all the simulations performed in the probabilistic sensitivity analysis, 99 % indicated that the incremental cost-effectiveness ratio of the 5-grass pollen tablet treatment was below the threshold of € 30,000/QALY in patients with medium and high AAdSS, whereas it was found to be dominated in 67 % of simulations related to patients with low AAdSS.

Conclusion

The 5-grass pollen tablet is a cost-effective treatment for adult AR patients with a medium or high AAdSS. This finding should be carefully considered when deciding the management strategy for these patients.

Immunological markers in allergic rhinitis patients treated with date palm immunotherapy

OBJECTIVE

Allergic rhinitis (AR) is regulated by the local production and release of several cytokines. Allergen specific immunotherapy (IT) has been widely used for many years as a specific treatment of allergic diseases. This study aimed to investigate the changes in clinical and immunological markers before and after Phoenix dactylifera IT in AR patients.

MATERIALS AND METHODS

Total symptom score and levels of total immunoglobulin E (IgE), albumin, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-10, IL-4, and IL-13 were measured in the serum and nasal samples of thirty non-atopic healthy controls and thirty patients with allergic rhinitis before and after 15 months of IT.

RESULTS

We found significantly higher concentrations of serum TNF-α and nasal TNF-α and IL-13, and significantly lower concentration of nasal IL-10, in allergic patients than in non-allergic. Moreover, serum and nasal IL-10 increased significantly after IT. However, there was neither a significant reduction in total IgE nor a significant increase in IFN-γ at the end of IT.

CONCLUSIONS

Our data show a clinical improvement associated with a decline in some inflammation parameters after IT. Moreover, date palm IT induced a significant increase in serum and nasal IL-10 levels.