Transcriptome analysis reveals the alleviating effect of Polysaccharide of Atractylodes macrocephala Koidz on thymic involution in Magang geese

Thymic involution is one of the important causes of decreased immunity in the body. Noncoding RNAs (miRNAs and lncRNAs) play crucial roles in regulating organ growth and development. Polysaccharide of Atractylodes macrocephala Koidz (PAMK) is widely acknowledged for its anti-oxidant, anti-aging, and immune-enhancing effects. However, its potential application in preventing the age-related thymic involution of Magang geese has not been previously reported. In this study, 54 4-month-old Magang geese were randomly divided into 3 groups, the thymus and serum of 18 geese were collected aseptically after 3 days of prefeeding period, and the remaining geese were randomly divided into control and PAMK groups (3 replicates per group and 6 Magang geese per replicate). Geese in the control group were fed a basal diet, and geese in the PAMK group were fed a basal diet supplemented with 400 mg/kg PAMK. The thymus and serum were collected 1 month later. The results of thymus index measurement showed that PAMK could alleviate thymus index. Furthermore, compared with the M5-Control group, HE staining showed that PAMK made the proportion of thymus medulla increased, and the boundary between cortex and medulla was clearer. Antioxidant function and cytokine content detection showed that, compared with the M5-Control group, PAMK increased T-AOC and GSH-Px levels in thymus, increased T-AOC level and SOD activity in serum, decreased MDA content in thymus and serum, and decreased IL-1β, IL-6 and TNF-α levels. To further explore the mechanism, 3 samples from the control and PAMK groups were selected for RNA-Seq. Through transcriptome analysis and prediction, a triple regulatory ceRNA network of 9 mRNAs, 11 miRNAs and 32 lncRNAs associated with alleviating thymic involution was constructed. Moreover, these genes were respectively enriched in the PPAR, Cytokine-cytokine receptor interaction, WNT, Apelin and MAPK signaling pathways. In summary, PAMK may alleviate age-related thymic involution in Magang geese by alleviating the thymus index, increasing the antioxidant level and regulating the cytokine content, potentially via the PPAR, Cytokine-cytokine receptor interaction, WNT, Apelin, and MAPK signaling pathways.