Amaral Eduardo P, Riteau Nicolas, Moayeri Mahtab, Maier Nolan, Mayer-Barber Katrin D, Pereira Rosana M, Lage Silvia L, Kubler Andre, Bishai William R, D'Império-Lima Maria R, Sher Alan, Andrade Bruno B
Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States.
Inflammation and Innate Immunity Unit, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States.
Front Immunol. 2018 Jun 21;9:1427. doi: 10.3389/fimmu.2018.01427. eCollection 2018.
Lysosomal cathepsin B (CTSB) has been proposed to play a role in the induction of acute inflammation. We hypothesised that the presence of active CTSB in the cytosol is crucial for NLRP3-inflammasome assembly and, consequently, for mature IL-1β generation after mycobacterial infection . Elevated levels of CTSB was observed in the lungs of mice and rabbits following infection with (Mtb) H37Rv as well as in plasma from acute tuberculosis patients. H37Rv-infected murine bone marrow-derived macrophages (BMDMs) displayed both lysosomal leakage, with release of CTSB into the cytosol, as well as increased levels of mature IL-1β. These responses were diminished in BMDM infected with a mutant H37Rv deficient in ESAT-6 expression. Pharmacological inhibition of cathepsin activity with CA074-Me resulted in a substantial reduction of both mature IL-1β production and caspase-1 activation in infected macrophages. Moreover, cathepsin inhibition abolished the interaction between NLRP3 and ASC, measured by immunofluorescence imaging in H37Rv-infected macrophages, demonstrating a critical role of the enzyme in NLRP3-inflammasome activation. These observations suggest that during Mtb infection, lysosomal release of activated CTSB and possibly other cathepsins inhibitable by CA07-Me is critical for the induction of inflammasome-mediated IL-1β processing by regulating NLRP3-inflammasome assembly in the cytosol.
溶酶体组织蛋白酶B（CTSB）被认为在急性炎症的诱导中起作用。我们假设，胞质溶胶中活性CTSB的存在对于NLRP3炎性小体的组装至关重要，因此对于分枝杆菌感染后成熟白细胞介素-1β（IL-1β）的产生也至关重要。在用结核分枝杆菌（Mtb）H37Rv感染后的小鼠和兔子的肺中以及急性结核病患者的血浆中，观察到CTSB水平升高。感染H37Rv的小鼠骨髓来源的巨噬细胞（BMDM）既表现出溶酶体渗漏，CTSB释放到胞质溶胶中，也表现出成熟IL-1β水平升高。在用缺乏ESAT-6表达的突变型H37Rv感染的BMDM中，这些反应减弱。用CA074-Me对组织蛋白酶活性进行药理抑制导致感染的巨噬细胞中成熟IL-1β的产生和半胱天冬酶-1的激活均大幅降低。此外，通过在感染H37Rv的巨噬细胞中进行免疫荧光成像测量，组织蛋白酶抑制消除了NLRP3与凋亡相关斑点样蛋白（ASC）之间的相互作用，证明了该酶在NLRP3炎性小体激活中的关键作用。这些观察结果表明，在结核分枝杆菌感染期间，活化的CTSB以及可能其他可被CA07-Me抑制的组织蛋白酶从溶酶体释放，对于通过调节胞质溶胶中的NLRP3炎性小体组装来诱导炎性小体介导的IL-1β加工至关重要。
