Novel developments in the mechanisms of immune tolerance to allergens

The multifaceted nature of IL-10: regulation, role in immunological homeostasis and its relevance to cancer, COVID-19 and post-COVID conditions

Interleukin-10 (IL-10) is a pleiotropic cytokine that has a fundamental role in modulating inflammation and in maintaining cell homeostasis. It primarily acts as an anti-inflammatory cytokine, protecting the body from an uncontrolled immune response, mostly through the Jak1/Tyk2 and STAT3 signaling pathway. On the other hand, IL-10 can also have immunostimulating functions under certain conditions. Given the pivotal role of IL-10 in immune modulation, this cytokine could have relevant implications in pathologies characterized by hyperinflammatory state, such as cancer, or infectious diseases as in the case of COVID-19 and Post-COVID-19 syndrome. Recent evidence proposed IL-10 as a predictor of severity and mortality for patients with acute or post-acute SARS-CoV-2 infection. In this context, IL-10 can act as an endogenous danger signal, released by tissues undergoing damage in an attempt to protect the organism from harmful hyperinflammation. Pharmacological strategies aimed to potentiate or restore IL-10 immunomodulatory action may represent novel promising avenues to counteract cytokine storm arising from hyperinflammation and effectively mitigate severe complications. Natural bioactive compounds, derived from terrestrial or marine photosynthetic organisms and able to increase IL-10 expression, could represent a useful prevention strategy to curb inflammation through IL-10 elevation and will be discussed here. However, the multifaceted nature of IL-10 has to be taken into account in the attempts to modulate its levels.

Markers of tolerance development to food allergens

IgE-mediated reactions to food allergens are the most common cause of anaphylaxis in childhood. Although allergies to cow's milk, egg, or soy proteins, in contrast to peanut and tree nut allergens, resolve within the first 6 years of life in up to 60% due to natural tolerance development, this process is not well understood. At present, there is no cure or treatment for food allergy that would result in an induction of tolerance to the symptom-eliciting food. Avoidance, providing an emergency plan and education, is the standard of treatment. Oral immunotherapeutic approaches have been proven reasonable efficacy; however, they are associated with high rates of side-effects and low numbers of patients achieving tolerance. Nevertheless, mechanisms that take place during oral immunotherapy may help to understand tolerance development. On the basis of these therapeutic interventions, events like loss of basophil activation and induction of regulatory lymphocyte subsets and of blocking antibodies have been described. Their functional importance at a clinical level, however, remains to be investigated in detail. Consequently, there is eminent need to understand the process of tolerance development to food allergens and define biomarkers to develop and monitor new treatment strategies for food allergy.

Immunologic alterations and efficacy of subcutaneous immunotherapy with Dermatophagoides pteronyssinus in monosensitized and polysensitized patients

BACKGROUND

There is a continuing debate about whether monoallergen subcutaneous immunotherapy (SCIT) is able to modulate immune and clinical responses toward main causal allergen in polysensitized patients.

OBJECTIVE

To investigate short-term immunologic changes and clinical effectiveness of SCIT with Dermatophagoides pteronyssinus in monosensitized and polysensitized patients who have rhinitis with or without asthma.

METHODS

Nineteen monosensitized and 24 polysensitized patients participated in this prospective, self-placebo-controlled, interventional study. Cluster immunotherapy with D pteronyssinus was administered after 2 months of placebo in both groups. Immunologic parameters, including CD203c expression on basophils after allergen stimulation, total IgE, specific IgE, and specific IgG4, were evaluated at baseline, after placebo, and after immunotherapy. Clinical effectiveness was assessed using monthly symptom-medication scores, visual analog scale, quality-of-life questionnaire, and nasal allergen provocation test.

RESULTS

At baseline, polysensitized patients had higher CD203c expression on basophils than monosensitized patients (P = .007). Activated basophils expressing CD203c, total IgE, and specific IgG4 were significantly increased after immunotherapy compared with baseline and placebo in the polysensitized group (P < .025). After immunotherapy, specific IgE and D pteronyssinus-induced CD203c expression were significantly higher in polysensitized than monosensitized patients (P < .05). The total symptom scores and the Mini Rhinoconjunctivitis Quality of Life Questionnaire scores in polysensitized patients and the visual analog scale scores in both groups were lower after immunotherapy compared with baseline and placebo (P < .025). Titrated nasal allergen provocation test with D pteronyssinus increased after immunotherapy in the monosensitized group (P < .05).

CONCLUSION

This study indicates that monosensitized and polysensitized patients have distinct humoral response and basophil behavior to SCIT. However, a single-allergen immunotherapy corresponding to the most clinically troublesome allergy in polysensitized patients can lead to early clinical efficacy comparable to that seen in monosensitized patients.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01795846.

Immunotherapy in allergy and cellular tests: state of art

The basophil activation test (BAT) is an in vitro assay where the activation of basophils upon exposure to various IgE-challenging molecules is measured by flow cytometry. It is a cellular test able to investigate basophil behavior during allergy and allergy immunotherapy. A panoply of critical issues and suggestive advances have rendered this assay a promising yet puzzling tool to endeavor a full comprehension of innate immunity of allergy desensitization and manage allergen or monoclonal anti-IgE therapy. In this review a brief state of art of BAT in immunotherapy is described focusing onto the analytical issue pertaining BAT performance in allergy specific therapy.

Molecular biomarkers for grass pollen immunotherapy

Grass pollen allergy represents a significant cause of allergic morbidity worldwide. Component-resolved diagnosis biomarkers are increasingly used in allergy practice in order to evaluate the sensitization to grass pollen allergens, allowing the clinician to confirm genuine sensitization to the corresponding allergen plant sources and supporting an accurate prescription of allergy immunotherapy (AIT), an important approach in many regions of the world with great plant biodiversity and/or where pollen seasons may overlap. The search for candidate predictive biomarkers for grass pollen immunotherapy (tolerogenic dendritic cells and regulatory T cells biomarkers, serum blocking antibodies biomarkers, especially functional ones, immune activation and immune tolerance soluble biomarkers and apoptosis biomarkers) opens new opportunities for the early detection of clinical responders for AIT, for the follow-up of these patients and for the development of new allergy vaccines.