RESUMO
Systemic lupus erythematosus severity correlates with elevated serum levels of type I IFNs, cytokines produced in large quantities by plasmacytoid dendritic cells (pDC) in response to engagement of TLR7 and TLR9 with endocytosed nucleic acids. B cell adaptor for PI3K (BCAP) promoted many aspects of TLR7-driven lupus-like disease, including Isg15 and Ifit1 expression in blood and an immature pDC phenotype associated with higher IFN production. BCAP-/- mice produced significantly less serum IFN-α than wild-type mice after injection of TLR9 agonist, and BCAP promoted TLR7 and TLR9-induced IFN-α production specifically in pDC. TLR-induced IFN-α production in pDC requires DOCK2-mediated activation of Rac1 leading to activation of IKKα, a mechanism we show was dependent on BCAP. BCAP-/- pDC had decreased actin polymerization and Rac1 activation and reduced IKKα phosphorylation upon TLR9 stimulation. We show a novel role for BCAP in promoting TLR-induced IFN-α production in pDC and in systemic lupus erythematosus pathogenesis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/imunologia , Células Dendríticas/imunologia , Interferon-alfa/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Glicoproteínas de Membrana/imunologia , Plasmócitos/imunologia , Receptor 7 Toll-Like/imunologia , Receptor Toll-Like 9/imunologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Citocinas/genética , Citocinas/imunologia , Células Dendríticas/patologia , Feminino , Proteínas Ativadoras de GTPase/genética , Proteínas Ativadoras de GTPase/imunologia , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/imunologia , Interferon-alfa/genética , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/patologia , Masculino , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Knockout , Neuropeptídeos/genética , Neuropeptídeos/imunologia , Plasmócitos/patologia , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/imunologia , Receptor 7 Toll-Like/genética , Receptor Toll-Like 9/genética , Ubiquitinas/genética , Ubiquitinas/imunologia , Proteínas rac1 de Ligação ao GTP/genética , Proteínas rac1 de Ligação ao GTP/imunologiaRESUMO
PURPOSE: Stereotactic body radiotherapy (SBRT) is an emerging treatment modality for pancreatic ductal adenocarcinoma (PDAC), which can effectively prime cytotoxic T cells by inducing immunogenic tumor cell death in preclinical models. SBRT effects on human PDAC have yet to be thoroughly investigated; therefore, this study aimed to characterize immunomodulation in the human PDAC tumor microenvironment following therapy. EXPERIMENTAL DESIGN: Tumor samples were obtained from patients with resectable PDAC. Radiotherapy was delivered a median of 7 days prior to surgical resection, and sections were analyzed by multiplex IHC (mIHC), RNA sequencing, and T-cell receptor sequencing (TCR-seq). RESULTS: Analysis of SBRT-treated tumor tissue indicated reduced tumor cell density and increased immunogenic cell death relative to untreated controls. Radiotherapy promoted collagen deposition; however, vasculature was unaffected and spatial analyses lacked evidence of T-cell sequestration. Conversely, SBRT resulted in fewer tertiary lymphoid structures and failed to lessen or reprogram abundant immune suppressor populations. Higher percentages of PD-1+ T cells were observed following SBRT, and a subset of tumors displayed more clonal T-cell repertoires. CONCLUSIONS: These findings suggest that SBRT augmentation of antitumor immunogenicity may be dampened by an overabundance of refractory immunosuppressive populations, and support the continued development of SBRT/immunotherapy combination for human PDAC.