Bachiega Tatiana Fernanda, Dias-Melicio Luciane Alarcão, Fernandes Reginaldo Keller, de Almeida Balderramas Helanderson, Rodrigues Daniela Ramos, Ximenes Valdecir Farias, de Campos Soares Ângela Maria Victoriano
Department of Microbiology and Immunology, UNESP-São Paulo State University, Biosciences Institute, Botucatu, São Paulo, Brazil.
Department of Pathology, UNESP-São Paulo State University, Botucatu Medical School, Botucatu, São Paulo, Brazil.
Immunobiology. 2016 Feb;221(2):228-35. doi: 10.1016/j.imbio.2015.09.003. Epub 2015 Sep 14.
Paracoccidioides brasiliensis is a dimorphic fungus from the Paracoccidioides genus, which is the causative agent of paracoccidioidomycosis, a chronic, subacute or acute mycosis, with visceral and cutaneous involvement. This disease that is acquired through inhalation primarily attacks the lungs but, can spread to other organs. Phagocytic cells as neutrophils play an important role during innate immune response against this fungus, but studies on antifungal activities of these cells are scarce. In addition to their ability to eliminate pathogens by phagocytosis and antimicrobial secretions, neutrophils can trap and kill microorganisms by release of extracellular structures composed by DNA and antimicrobial proteins, called neutrophil extracellular traps (NETs). Here, we provide evidence that P. brasiliensis virulent strain (P. brasiliensis 18) induces NETs release. These structures were well evidenced by scanning electron microscopy, and specific NETs compounds such as histone, elastase and DNA were shown by confocal microscopy. In addition, we have shown that dectin-1 receptor is the main PRR to which fungus binds to induce NETS release. Fungi were ensnared by NETs, denoting the role of these structures in confining the fungus, avoiding dissemination. NETs were also shown to be involved in fungus killing, since fungicidal activity detected before and mainly after neutrophils activation with TNF-α, IFN-γ and GM-CSF was significantly inhibited by cocultures treatment with DNAse.
巴西副球孢子菌是一种来自副球孢子菌属的双相真菌，是副球孢子菌病的病原体，这是一种慢性、亚急性或急性真菌病，可累及内脏和皮肤。这种通过吸入获得的疾病主要侵袭肺部，但也可扩散至其他器官。吞噬细胞如中性粒细胞在针对这种真菌的固有免疫反应中发挥重要作用，但关于这些细胞抗真菌活性的研究很少。除了通过吞噬作用和抗菌分泌物消除病原体的能力外，中性粒细胞还可以通过释放由DNA和抗菌蛋白组成的细胞外结构来捕获和杀死微生物，这些结构称为中性粒细胞胞外陷阱（NETs）。在这里，我们提供证据表明巴西副球孢子菌毒力菌株（巴西副球孢子菌18）可诱导NETs释放。这些结构通过扫描电子显微镜得到了充分证实，共聚焦显微镜显示了特定的NETs成分，如组蛋白、弹性蛋白酶和DNA。此外，我们还表明，dectin-1受体是真菌结合以诱导NETs释放的主要模式识别受体。真菌被NETs捕获，这表明这些结构在限制真菌、避免其扩散方面的作用。NETs也被证明参与了真菌的杀伤，因为在用肿瘤坏死因子-α、干扰素-γ和粒细胞-巨噬细胞集落刺激因子激活中性粒细胞之前和之后检测到的杀真菌活性，在用DNA酶进行共培养处理后受到显著抑制。
