Trametes versicolor

All mice were maintained under specific‐pathogen free conditions. Six‐week‐old male C57BL/6 mice were purchased from Orient Bio (Seongnam, Korea) and allowed to adapt for at least 1 week prior to experiments. Mice were randomly assigned to control and treatment groups. Mice were intraperitoneally injected with β‐glucan peptide from the fungus Trametes versicolor (25 mg kg⁻¹; InvivoGen, CA, USA) or PBS. The dose of β‐glucan titrated yielded consistent results. After 7 d, the mice were subjected to bleomycin‐induced lung injury. Under anesthesia with Avertin solution (Sigma), the trachea of each mouse was surgically exposed, followed by intratracheal administration of bleomycin (3 U kg⁻¹; Sigma, B5507) in 40 µL PBS or PBS alone. The mice were sacrificed as indicated, and their BALF, lungs, and bone marrow tissues were further examined.

The β-glucan used in this study was β-glucan peptide, a high-molecular-weight polysaccharide extracted from the fungus Trametes versicolor (Invivogen, category code: tlrl-bgp). The β-glucan consists of a highly ramified glucan portion, including a β-(1,4) main chain and β-(1,3) side chain, with β-(1,6) side chains covalently linked to a polypeptide portion rich in aspartic, glutamic, and other amino acids. The main structure of β-glucan is shown in Fig. 1b. β-glucan was diluted in sterile phosphate buffer saline (PBS) to a concentration of 1 mg/ml.Fig. 1

Changes in general conditions, body weight, and survival rate after the administration of β-glucan in mice with NEC. a Comparison of appearance among the three groups. b The main structure of β-glucan. c Survival curves of neonatal mice in the three groups. n = 40 d Body weight changes of neonatal mice in the three groups. n = 10