Martin Penagos's research while affiliated with Imperial College London and other places

Allergen-specific immunotherapy for inhalant allergies, using allergen extracts of proven value, is highly effective in selected patients with allergic rhinoconjunctivitis and allergic asthma. Both subcutaneous and sublingual immunotherapy (SLIT) have been shown to modify the underlying cause of the disease, with long-term clinical benefits that persist for years after their discontinuation. Real-world studies have confirmed the long-term efficacy of allergen immunotherapy in allergic rhinitis (AR) and asthma and shown a reduction in the incidence of lower respiratory tract infections. Sublingual house dust mite (HDM) immunotherapy has been suggested to improve innate antiviral immunity—a likely explanation for this finding. Based on robust randomized controlled trials, the Global Initiative for Asthma (GINA) guideline has incorporated the use of SILT for the treatment of adults with HDM-driven asthma and concomitant AR, with sub-optimal control, regardless of the use of low-to-high doses of inhaled corticosteroids, as long as the patient’s forced expiratory volume in 1 second (FEV1) is > 70%.

Background: Allergen immunotherapy (AIT) is a well-established disease-modifying therapy for allergic rhinitis, yet the fundamental mechanisms underlying its clinical effect remain inadequately understood. Objective: The GRASS study was a randomized, double-blind, placebo-controlled trial of timothy grass allergic individuals who received 2 years of placebo (n=30), subcutaneous (SCIT) (n=27), or sublingual immunotherapy (SLIT) (n=27) and were then followed for 1 additional year. Here we used yearly biospecimens from the GRASS study to identify molecular mechanisms of response. Methods: We utilized longitudinal transcriptomic profiling of nasal brush and peripheral blood mononuclear cell (PBMC) samples after allergen provocation to uncover airway and systemic expression pathways mediating responsiveness to AIT. Results: SCIT and SLIT demonstrated similar changes in gene module expression over time. In nasal samples, alterations included downregulation of pathways of mucus hypersecretion, leukocyte migration/activation, and endoplasmic reticulum stress (log2 fold changes (logFC) -0.133 to -0.640, FDRs <0.05). Interestingly, we observed upregulation of modules related to epithelial development, junction formation, and lipid metabolism (logFC 0.104 to 0.393, FDRs <0.05). In PBMCs, modules related to cellular stress response and type 2 cytokine signaling were reduced by immunotherapy (logFC -0.611 to -0.828, FDRs <0.05). Expression of these modules was also significantly associated with both Total Nasal Symptom Score and Peak Nasal Inspiratory Flow responses, indicating important links among treatment, module expression, and allergen response. Conclusion: Our results identify specific molecular responses of the nasal airway impacting barrier function, leukocyte migration activation, and mucus secretion, that are affected by both SCIT and SLIT, offering potential targets to guide novel strategies for AIT.

Allergen immunotherapy is highly effective in selected patients with allergic rhinitis, allergic asthma, and Hymenoptera venom allergy. Unlike anti-allergic drugs, both subcutaneous and sublingual immunotherapies have been shown to modify the underlying cause of the disease, with proved long-term clinical benefits after treatment cessation. In this review, we analyzed 10 randomized, double-blind, placebo controlled clinical trials of allergen immunotherapy that included blinded follow-up for at least 1 year after treatment withdrawal. Three studies of pollen subcutaneous immunotherapy provided evidence that a sustained, tolerogenic effect of subcutaneous immunotherapy can be achieved after 3 years of treatment. Six trials of sublingual immunotherapy provided robust evidence for long-term clinical benefit and persistent immunologic changes after grass pollen, house-dust mite, or Japanese cedar immunotherapy, whereas a clinical trial of both sublingual and subcutaneous grass pollen immunotherapies showed that 2 years of immunotherapy were efficacious but insufficient to induce long-term tolerance. These studies strongly supported international guidelines that recommend at least 3 years of allergen immunotherapy of proven value to achieve disease modification and sustained clinical and immunologic tolerance.

Allergen immunotherapy is effective for the treatment of allergic rhinitis, allergic asthma and Hymenoptera venom allergy. In view of potential side effects, cost, and the necessary patient commitment, an important question is whether allergen immunotherapy provides persistent clinical benefits after treatment discontinuation. Here we appraise the existing evidence for long-term effects of both subcutaneous and sublingual immunotherapy in terms of clinical efficacy, immune mechanisms, prevention of asthma development and prevention of new allergen sensitisations. Evidence from large, randomised, double-blind, placebo-controlled clinical trials that include a follow-up phase after treatment cessation demonstrate long-term efficacy. The data strongly support recommendations in international guidelines that both sublingual and subcutaneous immunotherapy should be continued for a minimum of 3 years to achieve disease modification and long-term tolerance. Grass pollen immunotherapy for seasonal rhinitis may inhibit the onset of asthma symptoms and requirements for asthma medication. Whether early intervention in infancy with mite sublingual immunotherapy may prevent asthma remains to be tested.

Long-term efficacy that occurs with allergen immunotherapy of proven value is associated with decreases in IgE-dependent activation of mast cells and tissue eosinophilia. This suppression of type 2 immunity is accompanied by early induction of regulatory T cells, immune deviation in favor of TH1 responses, and induction of local and systemic IgG, IgG4, and IgA antibodies. These “protective” antibodies can inhibit allergen-IgE complex formation and consequent mast cell triggering and IgE-facilitated TH2-cell activation. Recent studies have highlighted the importance of innate responses mediated by type 2 dendritic cells and innate lymphoid cells in allergic inflammation. These cell types are under the regulation of cytokines such as thymic stromal lymphopoietin and IL-33 derived from the respiratory epithelium. Novel subsets of regulatory cells induced by immunotherapy include IL-35–producing regulatory T cells, regulatory B cells, a subset of T follicular cells (TFR cells), and IL-10–producing group 2 innate lymphoid cells. These mechanisms point to biomarkers that require testing for their ability to predict clinical response to immunotherapy and to inform novel approaches for better efficacy, safety, and long-term tolerance.

Purpose of review: We evaluated the time-course of clinical and immunologic changes that occur during and after cessation of sublingual and subcutaneous allergen immunotherapy for inhalant allergies. Recent findings: Increases in production of inhibitory cytokines, such as IL-10 and allergen-specific IgE and IgG4 antibodies are induced within weeks of starting immunotherapy for both seasonal and perennial allergens. In general, 2-4 months' immunotherapy is needed for onset of efficacy whereas maximal clinical effect is achieved within 1-2 years of treatment. Therefore, assuming optimal patient selection, good compliance and at least moderate allergen exposure, if immunotherapy is ineffective at 2 years, it is reasonable to discontinue the treatment. For long-term clinical efficacy, at least 3 years of either subcutaneous or sublingual immunotherapy is required and this results in clinical and immunologic tolerance -- persistence of clinical benefits and suppression of type 2 immunity for years after discontinuation of treatment. Summary: Both sublingual and subcutaneous immunotherapy are effective and well tolerated for respiratory allergy. Clinical and immunological changes occur at early stages of treatment. Long-term evaluations support recommendations in international guidelines that both routes of administration should be continued for a minimum of 3 years to achieve disease modification and long-term tolerance.

Rationale Subcutaneous and sublingual immunotherapy are effective for allergic rhinitis. An important question is whether allergen immunotherapy provides a sustained clinical effect after treatment cessation. In view of potential side effects, cost and the necessary patient commitment, long-term benefit is an important consideration for the recommendation of immunotherapy over standard pharmacotherapy. Purpose of review In this review, we analyse the existing evidence for long-term effects of both routes of administration in the context of double-blind, placebo-controlled, randomised clinical trials that included a follow-up phase of at least 1 year after treatment cessation. Recent findings Overall, evidence suggests that 3 years of either subcutaneous or sublingual immunotherapy result in clinical benefit and immunological changes consistent with allergen-specific tolerance sustained for at least 2–3 years after treatment cessation. Summary The data presented here support recommendations in international guidelines that both routes of administration should be continued for a minimum of 3 years. Gaps in the evidence remain regarding the long-term efficacy of immunotherapy for perennial rhinitis and studies performed in children.

Background: The European Academy of Allergy and Clinical Immunology (EAACI) is in the process of developing Guidelines on Allergen Immunotherapy (AIT) for Allergic Rhinoconjunctivitis. To inform the development of clinical recommendations, we undertook a systematic review to assess the effectiveness, cost-effectiveness, and safety of AIT in the management of allergic rhinoconjunctivitis. Methods: We searched nine international biomedical databases for published, inprogress, and unpublished evidence. Studies were independently screened by two reviewers against predefined eligibility criteria and critically appraised using established instruments. Our primary outcomes of interest were symptom, medication, and combined symptom and medication scores. Secondary outcomes of interest included cost-effectiveness and safety. Data were descriptively summarized and then quantitatively synthesized using random-effects meta-analyses. Results: We identified 5960 studies of which 160 studies satisfied our eligibility criteria. There was a substantial body of evidence demonstrating significant reductions in standardized mean differences (SMD) of symptom (SMD 0.53, 95% CI 0.63, 0.42), medication (SMD 0.37, 95% CI 0.49, 0.26), and combined symptom and medication (SMD 0.49, 95% CI 0.69, 0.30) scores while on treatment that were robust to prespecified sensitivity analyses. There was in comparison a more modest body of evidence on effectiveness post-discontinuation of AIT, suggesting a benefit in relation to symptom scores. Conclusions: AIT is effective in improving symptom, medication, and combined symptom and medication scores in patients with allergic rhinoconjunctivitis while on treatment, and there is some evidence suggesting that these benefits are maintained in relation to symptom scores after discontinuation of therapy.<br/