Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America.
PLoS One. 2023 Mar 27;18(3):e0283161. doi: 10.1371/journal.pone.0283161. eCollection 2023.
IL-12p40 plays an important role in F. tularensis Live Vaccine Strain (LVS) clearance that is independent of its functions as a part of the heterodimeric cytokines IL-12p70 or IL-23. In contrast to WT, p35, or p19 knockout (KO) mice, p40 KO mice infected with LVS develop a chronic infection that does not resolve. Here, we further evaluated the role of IL-12p40 in F. tularensis clearance. Despite reduced IFN-γ production, primed splenocytes from p40 KO and p35 KO mice appeared functionally similar to those from WT mice during in vitro co-culture assays of intramacrophage bacterial growth control. Gene expression analysis revealed a subset of genes that were upregulated in re-stimulated WT and p35 KO splenocytes, but not p40 KO splenocytes, and thus are candidates for involvement in F. tularensis clearance. To directly evaluate a potential mechanism for p40 in F. tularensis clearance, we reconstituted protein levels in LVS-infected p40 KO mice using either intermittent injections of p40 homodimer (p80) or treatment with a p40-producing lentivirus construct. Although both delivery strategies yielded readily detectable levels of p40 in sera and spleens, neither treatment had a measurable impact on LVS clearance by p40 KO mice. Taken together, these studies demonstrate that clearance of F. tularensis infection depends on p40, but p40 monomers and/or dimers alone are not sufficient.
IL-12p40 在清除 F. tularensis Live Vaccine Strain (LVS) 方面发挥着重要作用，这与其作为异二聚体细胞因子 IL-12p70 或 IL-23 的一部分的功能无关。与 WT、p35 或 p19 敲除 (KO) 小鼠不同，感染 LVS 的 p40 KO 小鼠会发展为慢性感染，无法得到解决。在这里，我们进一步评估了 IL-12p40 在 F. tularensis 清除中的作用。尽管 IFN-γ 的产生减少，但 p40 KO 和 p35 KO 小鼠的原代脾细胞在体内共培养试验中控制巨噬细胞内细菌生长时，其功能似乎与 WT 小鼠相似。基因表达分析显示，一组基因在重新刺激的 WT 和 p35 KO 脾细胞中上调，但在 p40 KO 脾细胞中没有上调，因此这些基因可能参与了 F. tularensis 的清除。为了直接评估 p40 在 F. tularensis 清除中的潜在机制，我们使用 p40 同源二聚体 (p80) 的间歇性注射或使用产生 p40 的慢病毒构建体来重建感染 LVS 的 p40 KO 小鼠中的蛋白水平。尽管这两种传递策略都在血清和脾脏中产生了可检测到的 p40 水平，但两种治疗方法都没有对 p40 KO 小鼠清除 LVS 产生可衡量的影响。总之，这些研究表明，清除 F. tularensis 感染依赖于 p40，但 p40 单体和/或二聚体本身并不足够。
