Unveiling the multifunctional role of CXCL family chemokines in teleost immunity: a functional study of CXCL3 in yellowtail clownfish (Amphiprion clarkii).

CXCL3, a chemokine with broad immunomodulatory roles, was molecularly and functionally characterized in yellowtail clownfish (Amphiprion clarkii). The identified AcCXCL3 gene exhibited a tissue-specific expression pattern, with particularly high mRNA levels in the spleen and head kidney. Its expression was significantly upregulated in response to both viral and bacterial immune challenges, suggesting a strong inducible role in host defense. Functional assays using recombinant AcCXCL3 (rAcCXCL3) demonstrated its ability to regulate apoptosis by modulating bcl-2 and bax, exerting significant antiviral activity against viral hemorrhagic septicemia virus (VHSV), and enhancing wound healing. Notably, rAcCXCL3 promoted M1-like macrophage polarization, indicating its potential in directing pro-inflammatory innate immune responses. Gene expression analyses further revealed that rAcCXCL3 influenced key signaling pathways, including NF-κB, JAK/STAT, MyD88, and MAPK, underscoring its role in immune regulation. Collectively, this study highlights the significant role of AcCXCL3 as a multifunctional chemokine in the intricate regulation of immunity and tissue homeostasis in yellowtail clownfish. These findings contribute fundamental knowledge to our understanding of chemokine functions within aquatic vertebrates and pave the way for future research exploring their potential in fish health and disease management.