技术资料

Stem cells are highly resistant to viral infection compared to their differentiated progeny; however,the mechanism is mysterious. Here,we analyzed gene expression in mammalian stem cells and cells at various stages of differentiation. We find that,conserved across species,stem cells express a subset of genes previously classified as interferon (IFN) stimulated genes (ISGs) but that expression is intrinsic,as stem cells are refractory to interferon. This intrinsic ISG expression varies in a cell-type-specific manner,and many ISGs decrease upon differentiation,at which time cells become IFN responsive,allowing induction of a broad spectrum of ISGs by IFN signaling. Importantly,we show that intrinsically expressed ISGs protect stem cells against viral infection. We demonstrate the in vivo importance of intrinsic ISG expression for protecting stem cells and their differentiation potential during viral infection. These findings have intriguing implications for understanding stem cell biology and the evolution of pathogen resistance. View Publication

Mixed lineage kinase domain-like (MLKL)-dependent necroptosis is thought to be implicated in the death of mycobacteria-infected macrophages,reportedly allowing escape and dissemination of the microorganism. Given the consequent interest in developing inhibitors of necroptosis to treat Mycobacterium tuberculosis (Mtb) infection,we used human pharmacologic and murine genetic models to definitively establish the pathophysiological role of necroptosis in Mtb infection. We observed that Mtb infection of macrophages remodeled the intracellular signaling landscape by upregulating MLKL,TNFR1,and ZBP1,whilst downregulating cIAP1,thereby establishing a strong pro-necroptotic milieu. However,blocking necroptosis either by deleting Mlkl or inhibiting RIPK1 had no effect on the survival of infected human or murine macrophages. Consistent with this,MLKL-deficiency or treatment of humanized mice with the RIPK1 inhibitor Nec-1s did not impact on disease outcomes in vivo,with mice displaying lung histopathology and bacterial burdens indistinguishable from controls. Therefore,although the necroptotic pathway is primed by Mtb infection,macrophage necroptosis is ultimately restricted to mitigate disease pathogenesis. We identified cFLIP upregulation that may promote caspase 8-mediated degradation of CYLD,and other necrosome components,as a possible mechanism abrogating Mtb's capacity to coopt necroptotic signaling. Variability in the capacity of these mechanisms to interfere with necroptosis may influence disease severity and could explain the heterogeneity of Mtb infection and disease. View Publication

Neutrophils are the most abundant WBCs and have an essential role in the clearance of pathogens. Tight regulation of neutrophil numbers and their recruitment to sites of inflammation is critical in maintaining a balanced immune response. In various inflammatory conditions,such as rheumatoid arthritis,vasculitis,cystic fibrosis,and inflammatory bowel disease,increased serum G-CSF correlates with neutrophilia and enhanced neutrophil infiltration into inflamed tissues. We describe a fully human therapeutic anti-G-CSFR antibody (CSL324) that is safe and well tolerated when administered via i.v. infusion to cynomolgus macaques. CSL324 was effective in controlling G-CSF-mediated neutrophilia when administered either before or after G-CSF. A single ascending-dose study showed CSL324 did not alter steady-state neutrophil numbers,even at doses sufficient to completely prevent G-CSF-mediated neutrophilia. Weekly infusions of CSL324 (%10 mg/kg) for 3 wk completely neutralized G-CSF-mediated pSTAT3 phosphorylation without neutropenia. Moreover,repeat dosing up to 100 mg/kg for 12 wk did not result in neutropenia at any point,including the 12-wk follow-up after the last infusion. In addition,CSL324 had no observable effect on basic neutrophil functions,such as phagocytosis and oxidative burst. These data suggest that targeting G-CSFR may provide a safe and effective means of controlling G-CSF-mediated neutrophilia as observed in various inflammatory diseases. View Publication

Efficient gene transfer into human hematopoietic stem cells (HSCs) is an important goal in the study of the hematopoietic system as well as for gene therapy of hematopoietic disorders. A lentiviral vector based on the human immunodeficiency virus (HIV) was able to transduce human CD34+ cells capable of stable,long-term reconstitution of nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. High-efficiency transduction occurred in the absence of cytokine stimulation and resulted in transgene expression in multiple lineages of human hematopoietic cells for up to 22 weeks after transplantation. View Publication