Department of Biology, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
J Immunol. 2012 Oct 15;189(8):4060-8. doi: 10.4049/jimmunol.1103455. Epub 2012 Sep 14.
Experimental pulmonary Cryptococcus neoformans infection in BALB/c mice is associated with polarized Th2-type cytokine production, alternative macrophage activation, and severe bronchopneumonia. In contrast, pulmonary infection with a C. neoformans strain that secretes IFN-γ, H99γ, elicits Th1-type cytokine production and classical macrophage activation. Additionally, mice infected with H99γ resolve the acute infection and are subsequently protected against challenge with wild-type C. neoformans. The present study characterizes macrophage activation during the protective response to wild-type C. neoformans in mice previously immunized with H99γ. We observed increased pulmonary Th1-type cytokine production in lung homogenates and classical macrophage activation as evidenced by enhanced expression of inducible NO synthase in the lungs of H99γ-immunized mice compared with mice given a nonprotective immunization with heat-killed C. neoformans (HKCn). Furthermore, macrophages isolated from H99γ-immunized mice on day 7 postchallenge and cultured in vitro were fungistatic against C. neoformans, whereas cryptococcal growth was uncontrolled within macrophages from HKCn-immunized mice. Th2-type cytokine production and induction of alternatively activated macrophages were also observed in lungs of HKCn-immunized mice during rechallenge. Gene expression arrays showed that classical macrophage activation during challenge infection in H99γ-immunized mice was associated with induction of the transcription factor STAT1 and its downstream targets IFN regulatory factor-1, suppressor of cytokine signaling-1, CXCL9, and CXCL10. These studies demonstrate that protective responses to C. neoformans challenge in immunized mice include classical macrophage activation and enhanced macrophage fungistasis of C. neoformans yeasts. Finally, the classical activation phenotype of protective anticryptococcal macrophages is likely mediated via STAT1 signal transduction pathways.
实验性肺新型隐球菌感染 BALB/c 小鼠与极化的 Th2 型细胞因子产生、替代型巨噬细胞激活和严重的支气管肺炎有关。相比之下，感染分泌 IFN-γ的新型隐球菌菌株 H99γ会引发 Th1 型细胞因子产生和经典的巨噬细胞激活。此外，感染 H99γ的小鼠会清除急性感染，并随后对野生型新型隐球菌的攻击产生保护。本研究描述了先前用 H99γ免疫的小鼠对野生型新型隐球菌感染的保护性反应期间的巨噬细胞激活。与给予非保护性灭活新型隐球菌（HKCn）免疫的小鼠相比，我们观察到 H99γ 免疫小鼠的肺匀浆中 Th1 型细胞因子产生增加，并且经典的巨噬细胞激活，表现为肺部诱导型一氧化氮合酶的表达增强。此外，与 HKCn 免疫小鼠的巨噬细胞相比，从 H99γ 免疫小鼠分离的巨噬细胞在第 7 天再次感染后的体外培养中对新型隐球菌具有抑菌作用，而 HKCn 免疫小鼠的巨噬细胞中新型隐球菌的生长无法控制。在再次感染时，也观察到 HKCn 免疫小鼠的肺部产生 Th2 型细胞因子和诱导替代性激活的巨噬细胞。基因表达谱显示，在 H99γ 免疫小鼠的挑战感染期间，经典的巨噬细胞激活与转录因子 STAT1 及其下游靶标 IFN 调节因子-1、细胞因子信号转导抑制因子-1、CXCL9 和 CXCL10 的诱导有关。这些研究表明，免疫小鼠对新型隐球菌挑战的保护性反应包括经典的巨噬细胞激活和增强的新型隐球菌酵母对巨噬细胞的抑菌作用。最后，保护性抗隐球菌巨噬细胞的经典激活表型可能通过 STAT1 信号转导途径介导。
