Current possibilities and future perspectives for improving efficacy of allergen-specific sublingual immunotherapy

Therapeutic potential of mesenchymal stem cell-derived exosomes for allergic airway inflammation

Due to their immunomodulatory capacities, mesenchymal stem cells (MSCs) have been extensively used as therapeutic approaches in cell-based therapy for various inflammatory diseases. Several lines of studies have shown that the most beneficial effects of MSCs are associated with MSC-derived exosomes. Exosomes are nanoscale extracellular vesicles that contain important biomolecules such as RNA, microRNAs (miRNAs), DNA, growth factors, enzymes, chemokines, and cytokines that regulate immune cell functions and parenchymal cell survival. Recently, exosomes, especially MSC-derived exosomes, have been shown to have protective effects in allergic airway inflammation. This review focused on the immune-regulatory potential of MSC-derived exosomes as nanoscale delivery systems in the treatment of allergic airway inflammation.

Sublingual prophylactic administration of OVA-loaded MSC-derived exosomes to prevent allergic sensitization

AIM

This study evaluated the immunomodulatory and delivery potential of adipose tissue-isolated MSC-derived exosomes as a prophylactic regimen through a sublingual route in the ovalbumin (OVA)-induced allergic asthma murine model.

MATERIAL AND METHODS

Balb/c mice received 10 μg/dose of OVA-enriched MSC-derived exosomes as a prophylactic regimen in six doses during three weeks, and then OVA sensitization was conducted through intraperitoneal and aerosol administration of allergen. The total cells and eosinophils counted in nasal lavage fluid (NALF) and lung tissues were assessed for histopathological analysis. In addition, the secretion of IFN-γ, IL-4, and TGF-β by spleen cells and serum OVA-specific IgE levels were measured via ELISA.

RESULTS

Significant reduction in the IgE levels and IL-4 production, along with elevated TGF-β levels, were observed. Also, limited cellular infiltrations and perivascular and peribronchiolar inflammation in the lung tissues and normal total numbers of cells and eosinophils in the NALF were reported.

CONCLUSION

Prophylactic regimen using OVA-enriched MSC-derived exosomes modulated immune responses and inhibited allergic OVA sensitization.

Mesenchymal stem cells and allergic airway inflammation; a therapeutic approach to induce immunoregulatory responses

Allergic airway inflammations are among the essential disorders worldwide that are already considered a significant concern. Mesenchymal stem cells (MSCs) are stromal cells with regenerative potential and immunomodulatory characteristics and are widely administered for tissue repair as an immunoregulatory agent in different inflammatory diseases. The current review summarized primary studies conducted to evaluate the therapeutic potential of MSCs for allergic airway disorders. In this case, modulation of airway pathologic inflammation and infiltration of inflammatory cells were examined, and modulation of the Th1/Th2 cellular balance and humoral responses. Also, the effects of MSCs on the Th17/Treg ratio and inducing Treg immunoregulatory responses along with macrophage and dendritic cell function were evaluated.

Immune response modulation by allergen loaded into mesenchymal stem cell-derived exosomes as an effective carrier through sublingual immunotherapy

BACKGROUND

Allergen-specific sublingual immunotherapy (SLIT) was considered an interesting needle-free alternative for subcutaneous immunotherapy (SCIT). Mesenchymal stem cell (MSC)-derived exosomes were introduced as potent nanoscale delivery systems with immunomodulatory potentials. The current study investigated the therapeutic efficacy of SLIT using ovalbumin (OVA)-enriched MSC-derived exosomes formulation in a murine model of allergic asthma.

MATERIAL AND METHODS

MSCs were harvested from mice adipose tissues. Then, exosomes were isolated, and OVA-loaded exosomes were prepared. Following sensitization, Balb/c mice received therapeutic formulation (10 μg/dose OVA-containing MSC-derived exosomes) twice a week for two months. Serum OVA-specific IgE levels as well as IFN-γ, IL-4, and TGF-β secretions by cultured splenocytes were measured by ELISA. Also, lung tissue underwent histopathologic analysis, and the numbers of inflammatory cells and eosinophils in nasopharyngeal lavage fluid (NALF) were examined.

RESULTS

SLIT using OVA-enriched exosomes significantly reduced IgE levels and IL-4 production, while the secretion of IFN-γ and TGF-β were significantly elevated. Also, a decrease was observed in the numbers of total cells and eosinophils in the NALF, and lower levels of perivascular and peribronchiolar inflammation and cellular infiltrations were observed in the lung tissue.

CONCLUSION

SLIT using OVA-loaded exosomes improved immunomodulatory responses and efficiently alleviated allergic inflammation.

The intriguing possibility of using probiotics in allergen-specific immunotherapy

Allergen immunotherapy (AIT) can be considered the etiological therapy for allergic rhinitis and hymenoptera venom allergy. Its role is increasingly emerging in the context of IgE mediated food allergy, where the achievement of tolerance, or the permanent resolution of an allergy, represents the optimal goal of AIT. AIT treatment, indicated in adults and children with allergic rhinitis, has a preventative effect on the development of asthma and can also be used when asthma is associated to rhinitis; however, it is not the first choice for treatment of isolated asthma. While knowledge on immunological mechanisms, efficacy, and safety of AIT is known, an intriguing line of investigation has arisen on how the action of AIT is modulated by the use of probiotics, starting from awareness that the microbiome is altered in allergic conditions: the use of probiotics in inducing the stimulation of innate immunity via toll-like receptor activation, thus acting as adjuvants in AIT, is hereby examined. Therefore, by analyzing literature on AIT and probiotics, we intend to draw attention to how the role and use of AIT are emerging as being increasingly important for both the short- and long-term management of allergic diseases and how recourse probiotics may represent an additional therapeutic strategy to modulate the effectiveness of AIT. However, further investigations are needed to better identify which probiotics to use, the dosage, and the optimal duration to obtain correct immunomodulation, and how to best customize their use, including a "AIT + probiotics" strategy in the field of precision medicine.

Loading Ovalbumin into Mesenchymal Stem Cell-Derived Exosomes as a Nanoscale Carrier with Immunomodulatory Potential for Allergen-Specific Immunotherapy

Background

Exosomes are nanoscale vesicles widely used as drug delivery systems. Mesenchymal stem cell (MSC)-derived exosomes have shown immunomodulatory potential. This study optimized loading OVA into the mice adipose tissue-derived MSC-isolated exosomes to prepare the OVA-MSC-exosome complex for allergen-specific immunotherapy.

Methods

MSCs were harvested from mice adipose tissue and characterized by flow cytometry and evaluating differentiation potential. The exosomes were isolated and characterized via Dynamic Light Scattering, Scanning Electron Microscopy, and flow cytometry. Different concentrations of ovalbumin were incubated with MSC-exosome in various durations to optimize a more suitable protocol. BCA and HPLC analysis were used to quantify, and DLS was applied to qualify the prepared formulation of the OVA-exosome complex.

Results

The harvested MSCs and isolated exosomes were characterized. Analysis of the OVA-exosome complex revealed that OVA in primary 500 μg/ml concentration and incubation for 6 h results in higher efficacy.

Conclusions

Loading OVA into MSC-derived exosomes was successfully optimized and could be administrated for allergen-specific immunotherapy in the animal model.