Heat shock cognate 70 protein like-2 protein in camphor pollen is one of the major culprits of asthma.

AIMS: In recent decades, Cinnamomum camphora have gradually become the main street trees in Shanghai. This study aims to investigate the allergenicity of camphor pollen.

MAIN METHODS: A total of 194 serum samples from patients with respiratory allergy were collected and analyzed. Through protein profile identification and bioinformatics analysis, we hypothesized that heat shock cognate protein 2-like protein (HSC70L2) is the major potential allergenic protein in camphor pollen. Recombinant HSC70L2 (rHSC70L2) was expressed and purified, and a mouse model of camphor pollen allergy was established by subcutaneous injection of total camphor pollen protein extract (CPPE) and rHSC70L2.

KEY FINDINGS: Specific IgE was found in the serum of 5 patients in response to camphor pollen and three positive bands were identified by Western blotting. Enzyme-linked immunosorbent assay (ELISA), Immune dot blot and Western blot experiments confirmed that CPPE and rHSC70L2 can cause allergies in mice. Moreover, rHSC70L2 induces polarization of peripheral blood CD4+ T cells to Th2 cells in patients with respiratory allergies and mice with camphor pollen allergy. Finally, we predicted the T cell epitope of the HSC70L2 protein, and through the mouse spleen T cell stimulation experiment, we found that the 295 EGIDFYSTITRARFE309 peptide induced T cells differentiation to Th2 and macrophages differentiation to the alternatively activated (M2) state. Moreover, 295 EGIDFYSTITRARFE309 peptide increased the serum IgE levels in mice.

SIGNIFICANCE: The identification of HSC70L2 protein can provide novel diagnostic and therapeutic targets for allergies caused by camphor pollen.