Research Article
TLR8 and TLR7/8 Activations Induce Tissue-specific Natural Killer Cell Gene Expressions in Rag1 Mutant Zebrafish Liver, Kidney, and Spleen
Preeti Judith Muire
,
Lora Petrie-Hanson*
Issue:
Volume 13, Issue 3, September 2025
Pages:
42-51
Received:
5 June 2025
Accepted:
18 June 2025
Published:
23 July 2025
Abstract: TLR ligands Resiquimod (TLR7/8) and Motolimod (TLR8) are used to activate NK cells and enhance immune defenses. This study reports the differential gene expressions of innate immune markers and Natural Killer (NK) cell lysins in rag1 mutant (rag MT) zebrafish to TLR8 and TLR7/8 activation in liver, kidney, and spleen tissues. Rag MT zebrafish were intracoelomically injected with Motolimod (VTX), Resiquimod (R848), or control saline. Gene expressions of interferon gamma (ifnγ), T-box transcription factor 21 (t-bet), novel immune type receptor 9 (nitr9), and NK lysins a, b, c, and d (nkla, nklb, nklc, nkld) were quantified at 6-, 12-, and 24-hours post-injection using quantitative PCR. We observed that the effects of TLR7/8 and TLR8 stimulation vary depending on the tissue type. R848 significantly upregulated ifnγ, t-bet, nitr9, and NK lysins across various tissues. In contrast, VTX had a more limited effect and primarily influenced nklc and nkld in the kidney and spleen, and nkld in the liver, suggesting tissue-specific responsiveness to TLR8. No significant changes in ifnγ or nkla expression were noted with VTX in any tissues, highlighting the specificity of TLR7 over TLR8 in these responses. Tissue-specific responses revealed dominant activation by TLR7/8 in the liver, particularly influencing ifnγ, t-bet, nitr9, nklb, and nklc. The kidney had high responsiveness to both TLR7/8 and TLR8. The spleen demonstrated broad gene activation by TLR7/8, but only nklc and nkld were significantly upregulated by TLR8. These findings demonstrate that TLR8 has selective effects, while TLR7/8 more broadly activates genes across the liver, kidney, and spleen in rag MT zebrafish. These NK cell gene expression findings suggest exposure to TLR7/8 and TLR8 ligands elicited differential effects across liver, kidney, and spleen tissues of rag MT zebrafish.
Abstract: TLR ligands Resiquimod (TLR7/8) and Motolimod (TLR8) are used to activate NK cells and enhance immune defenses. This study reports the differential gene expressions of innate immune markers and Natural Killer (NK) cell lysins in rag1 mutant (rag MT) zebrafish to TLR8 and TLR7/8 activation in liver, kidney, and spleen tissues. Rag MT zebrafish were ...
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