Luster, A. D. | Search bioRxiv

bioRxiv2020

During Aspergillus infection, neutrophil, monocyte-derived DC, and plasmacytoid DC enhance innate immune defense through CXCR3-dependent crosstalk

Aspergillus fumigatus, a ubiquitous mold, is a common cause of invasive aspergillosis (IA) in immunocompromised patients. Host defense against IA relies on lung-infiltrating neutrophils and monocyte-derived dendritic cells (Mo-DCs). Here, we demonstrate that plasmacytoid dendritic cells (pDCs), which are prototypically anti-viral cells, participate in innate immune crosstalk underlying mucosal antifungal immunity. Aspergillus-infected murine Mo-DCs and neutrophils recruited pDCs to the lung by releasing the CXCR3 ligands, CXCL9 and CXCL10, in a Dectin-1/Card9- and type I and III interferon-signaling dependent manner, respectively. During aspergillosis, circulating pDCs entered the lung in response to CXCR3-dependent signals. Via targeted pDC ablation, we found that pDCs were essential for host defense in the presence of normal neutrophil and Mo-DC numbers. Although interactions between pDC and fungal cells were not detected, pDCs regulated neutrophil NADPH oxidase activity and conidial killing. Thus, pDCs act as positive feedback amplifiers of neutrophil effector activity against inhaled mold conidia.

immunology↗

bioRxiv2020

Distinct functions of tissue-resident and circulating memory Th2 cells in allergic airway disease

Memory CD4+ T helper type 2 (Th2) cells are critical in driving allergic asthma pathogenesis, yet the mechanisms whereby tissue-resident memory Th2 cells (Th2 Trm) and circulating memory Th2 cells collaborate in vivo remain unclear. Here, using a house dust mite (HDM) model of allergic asthma and parabiosis, we demonstrate that Th2 Trm and circulating memory Th2 cells perform non-redundant functions in vivo. Upon HDM re-challenge, circulating memory Th2 cells trafficked into the lung parenchyma and ignited perivascular inflammation to promote eosinophil and CD4+ T cell recruitment. In contrast, Th2 Trm proliferated near airways and promoted mucus metaplasia, airway hyper-responsiveness, and airway eosinophil activation. Transcriptional analysis revealed that Th2 Trm and circulating memory Th2 cells share a core Th2 gene signature, but also exhibit distinct transcriptional profiles. Specifically, Th2 Trm express a tissue adaptation signature, including genes involved in regulating and interacting with extracellular matrix. Our findings demonstrate that Th2 Trm and circulating memory Th2 cells are functionally and transcriptionally distinct subsets with unique roles in promoting allergic airway disease. SUMMARYHow memory Th2 cell subsets orchestrate allergic airway inflammation remains unclear. Rahimi et al. use a murine model of allergic asthma and parabiosis to demonstrate that tissue-resident and circulating memory Th2 cells are functionally distinct subsets with unique roles in promoting allergic airway disease.

immunology↗