<b>Polysaccharide of </b><b><i>Atractylodes Macrocephala</i></b><b> Koidz alleviates Cyclophosphamide induced lymphocytes injury</b><b> in goslings</b>

The immune system of gosling is not fully developed, making them susceptible to pathogens, stress, and adverse environmental factors, which can lead to compromised immune function. Cyclophosphamide (<b>CTX)</b> is a commonly used immunosuppressive agent, causing DNA strand breaks and cell death, thereby inducing lymphocytes injury and reducing immune function. This study aimed to evaluate whether polysaccharide from <i>Atractylodes macrocephala</i> Koidz (<b>PAMK</b>) can alleviate CTX-induced lymphocyte injury in goslings and to elucidate its underlying mechanisms. One-day-old Magang goslings were divided into control, CTX, PAMK, and PAMK+CTX groups. Thymus morphology, lymphocyte apoptosis, cytokine/chemokine expression, and transcriptome profiles were assessed through histology, TUNEL staining, flow cytometry, RT-qPCR, and Western blot. CCL5 overexpression experiments were conducted in vitro to further validate the mechanistic pathway. PAMK significantly alleviated CTX-induced thymic damage, preserved thymocyte structure, and reduced lymphocyte apoptosis. Transcriptome and KEGG analyses revealed the chemokine signaling pathway as a key target. PAMK downregulated CCL5/CCR5 expression and restored downstream Src, PI3K, Raf, and ERK1/2 activity. In CCL5-overexpressing lymphocytes, PAMK reversed pro-apoptotic effects by modulating the same pathway, confirming its regulatory role. PAMK mitigates CTX-induced thymic injury in goslings by modulating the CCL5/CCR5-mediated chemokine signaling pathway, offering potential for developing immunomodulatory strategies in poultry.