关键词: 过敏性哮喘, 变应原, 益生菌, 气道炎症, 蛋白疫苗

Abstract:

Felis domesticus allergen 1 (Fel d 1), the major allergen responsible for cat-induced allergic diseases, can trigger symptoms ranging from mild allergic rhinitis to life-threatening asthmatic reactions. This study developed a novel immune intervention strategy based on an antigen delivery system: utilizing recombinant Escherichia coli Nissle 1917 (EcN) to achieve in vivo expression of rFel d 1, aiming to prevent allergic reactions induced by rFel d 1. The gene sequence of the major Fel d 1 was obtained from the NCBI GenBank database. The coding sequences (CDS) of Chain 1 and Chain 2 were selected, with a covalent linkage formed between the C-terminal cysteine residue (Cys) of Chain 1 and the N-terminal valine residue (Val) of Chain 2 to generate recombinant Fel d 1 (rFel d 1). A triple GS repeat sequence was introduced at the N-terminus of rFel d 1, while a 6×His tag was added to the C-terminus. After codon optimization, the construct was cloned into the pBad vector to generate the prokaryotic expression vector pBad-rFel d 1. The pBad-rFel d 1 plasmid was then transformed into EcN competent cells to construct the recombinant E. coli strain EcN^{rFel d 1}. In a murine allergy model, the preventive efficacy of EcN^{rFel d 1} against rFel d 1-induced allergic reactions was comprehensively evaluated. We found that pre-administration with the recombinant E. coli strain EcN^{rFel d 1} capable of expressing rFel d 1 in vivo could effectively prevent airway hyperresponsiveness and the elevation of IgE levels, protecte lung tissues from pathological changes and avoid local or systemic allergic reactions specifically activated by rFel d 1, and prevent the imbalance of Th1/Th2 and Th17/Treg in the body. Based on the inherent colonization advantages and sustained-release properties of probiotic EcN, this study developed a preventive recombinant E. coli strain EcN^{rFel d 1}, Which effectively prevents rFel d 1-induced allergic reactions by modulating Th1/Th2 and Treg/Th17 immune balance while inducing the production of blocking antibodies.

Key words: allergic asthma, allergens, probiotics, airway inflammation, protein vaccines