Immunotherapy with B cell epitopes ameliorates inflammatory responses in B alb/c mice

Summary Osmotin, a protein from the pathogenesis‐related family ( PR ‐5), has been identified as an allergen based on in‐silico and in‐vitro studies. In the present study, three B cell epitopes of osmotin with single and double amino acid modifications were studied for immunotherapy in a murine model. The single‐modification peptides ( P ‐1‐1, P ‐2‐1 and P ‐3‐1) and double‐modification peptides ( P ‐1‐2, P ‐2‐2 and P ‐3‐2) showed significantly lower immunoglobulin ( Ig)E binding with patients' sera compared to osmotin ( P  < 0·01). These peptides showed reduced IgE binding compared to the unmodified peptides ( B cell epitopes) P ‐1, P ‐2 and P ‐3. Among the modified peptides, P ‐2‐1, P ‐3‐1, P ‐2‐2 and P ‐3‐2 showed significant reduction in IgE binding and were used for immunotherapy in mice. The sera of mice group treated with peptides showed a significant increase in IgG 2a level and a significant decrease in IgE and IgG 1 levels ( P  < 0·05). The mice that received peptide immunotherapy showed a shift from a T helper type 2 ( T h2) to T h1 type where interferon ( IFN) ‐γ and interleukin ( IL) ‐10 levels were elevated, with a significant increase in groups treated with peptides P ‐3‐1 and P ‐3‐2 ( P  < 0·05). There was a reduction in the IL ‐4 and IL ‐5 levels in bronchoalveolar lavage fluid ( BALF ) in the peptide‐treated mice groups. Total cell count and eosinophil count in BALF of the peptide‐treated groups was also reduced compared to the phosphate‐buffered saline ( PBS)‐ treated group. Lung histology showed a significant reduction in cellular infiltrate in mice treated with P ‐2‐2 and P ‐3‐2 compared to PBS . In conclusion, peptides P ‐2‐2 and P ‐3‐2 lowered inflammatory responses and induced a T h1 response in mice.