Toll-like receptor 2 activators modulate oral tolerance in mice

Area of Science:

• Immunology
• Allergy Research
• Mucosal Immunity

Background:

• Toll-like receptor 2 (TLR2) is a key innate immunity receptor involved in mucosal immunity and allergic disease development.
• The role of TLR2 in oral tolerance and allergic sensitization to food antigens remains unclear, despite TLR2 activators being present in common foods.

Purpose of the Study:

• To investigate the impact of TLR2 expression and activation on the development of oral tolerance to food antigens.
• To evaluate the role of TLR2 in modulating immune responses to food antigens in a murine model.

Main Methods:

• Mice were orally administered ovalbumin (OVA) or peanut butter, with or without TLR2 activators (Pam3 CSK4 or FSL-1).
• Oral tolerance was assessed by analyzing antibody responses post-systemic antigen challenge.
• Regulatory T-cell (Treg) populations were analyzed in wild-type and TLR2(-/-) mice.
• Low-dose Pam3 CSK4 was tested as an oral adjuvant.

Main Results:

• Oral tolerance was successfully induced in both wild-type and TLR2(-/-) mice, with Treg responses observed.
• Oral TLR2 activation during antigen exposure altered oral tolerance, leading to significant IgE and IgA responses upon systemic challenge.
• Low-dose oral Pam3 CSK4 enhanced antigen-specific IgA responses.

Conclusions:

• TLR2 is not required for inducing oral tolerance but modulates IgE and IgA humoral responses during this process.
• Low-dose Pam3 CSK4 acts as an effective oral adjuvant, specifically boosting IgA production.
• Findings are relevant for optimizing oral allergen immunotherapy and oral vaccine strategies.