Hermansky-Pudlak Syndrome with an Improvement in the Respiratory Symptoms after the Administration of Pirfenidone: A Case Report.

Herein, we report a case of Hermansky-Pudlak syndrome (HPS) in which respiratory symptoms improved with pirfenidone treatment. A 43-year-old Japanese woman with oculocutaneous albinism presented with a cough and dyspnea. High-resolution computed tomography revealed areas of reticular and frosted lung opacities. The diagnosis of HPS was confirmed by a prolonged bleeding time and HPS1 gene mutation. Generally, there is no effective treatment for interstitial pneumonia associated with HPS except for lung transplantation. In the present case, the cough and dyspnea improved with pirfenidone administration. Therefore, clinicians should administer pirfenidone in challenging transplantation cases and during the waiting period for transplantation.

Identification of Siglec-1-negative alveolar macrophages with proinflammatory phenotypes in chronic obstructive pulmonary disease.

Alveolar macrophages (AMs) in patients with chronic obstructive pulmonary disease (COPD) orchestrate persistent inflammation in the airway. However, subpopulations of AMs participating in chronic inflammation have been poorly characterized. We previously reported that Siglec-1 expression on AMs, which is important for bacteria engulfment, was decreased in COPD. Here, we show that Siglec-1-negative AMs isolated from COPD lung tissues exhibit a proinflammatory phenotype and are associated with poor clinical outcomes in patients with COPD. Using flow cytometry, we segregated three subsets of AMs based on the expression of Siglec-1 and their side scattergram (SSC) and forward scattergram (FSC) properties: Siglec-1+SSChiFSChi, Siglec-1-SSChiFSChi, and Siglec-1-SSCloFSClo subsets. The Siglec-1-SSCloFSClo subset number was increased in COPD. RNA sequencing revealed upregulation of multiple proinflammatory signaling pathways and emphysema-associated matrix metalloproteases in the Siglec-1-SSCloFSClo subset. Gene set enrichment analysis indicated that the Siglec-1-SSCloFSClo subset adopted intermediate phenotypes between monocytes and mature alveolar macrophages. Functionally, these cells produced TNF-α, IL-6, and IL-8 at baseline, and these cytokines were significantly increased in response to viral RNA. The increase in Siglec-1-negative AMs in induced sputum is associated with future exacerbation risk and lung function decline in patients with COPD. Collectively, the novel Siglec-1-SSCloFSClo subset of AMs displays proinflammatory properties, and their emergence in COPD airways may be associated with poor clinical outcomes.NEW & NOTEWORTHY Alveolar macrophages (AMs) in patients with chronic obstructive pulmonary disease (COPD) orchestrate persistent inflammation in the airway. We find that Siglec-1-negative alveolar macrophages have a wide range of proinflammatory landscapes and a protease-expressing phenotype. Moreover, this subset is associated with the pathogenesis of COPD and responds to viral stimuli.

Decreased expression of airway epithelial Axl is associated with eosinophilic inflammation in severe asthma.

BACKGROUND: Airway epithelium-derived cytokines are critical to provoke and perpetuate type 2 inflammation in asthma. Yet it is poorly understood how this epithelial cell-driven inflammatory response is negatively regulated. We previously reported that Axl receptor tyrosine kinase was expressed by basal cells in the airway epithelium and had a role in defining their stem cell identity. However, whether and how Axl regulates airway type 2 inflammation remains unknown. METHODS: We performed immunofluorescence staining to compare Axl expression in airway epithelium between non-asthmatic subjects, mild-moderate asthma and severe asthma. We confirmed this result by interrogating public databases of global gene expression in endobronchial biopsies. We then quantified eosinophil numbers infiltrating into the trachea of wild-type or Axl-knockout mice that were intranasally treated with house dust mite extracts (HDM). Cell-based assays using siRNA targeting Axl were further performed to identify molecules involved in Axl-mediated regulation of inflammation. RESULTS: Histological assessments and transcriptome analyses revealed decreases in protein and mRNA of Axl in airway basal cells of severe asthmatics. This reduction of Axl expression was correlated with infiltration of eosinophils and mast cells in severe asthmatics. Eosinophil infiltration was more evident in the trachea of Axl-knockout mice in response to repetitive HDM administration. siRNA-mediated knockdown of Axl increased mRNA and protein expression of granulocyte macrophage-colony stimulating factor (GM-CSF) in human bronchial epithelial cells. CONCLUSIONS: Axl kinase expressed by basal cells may suppress excessive eosinophilic inflammation via inhibition of GM-CSF in the airway. Axl reduction has clinical implications for the pathogenesis of severe asthma.

Increased LHX9 expression in alveolar epithelial type 2 cells of patients with chronic obstructive pulmonary disease.

BACKGROUND: Alveolar epithelial type 2 (AT2) cells serve as stem cells in alveolar epithelium and are assumed to lose their stem cell function in the lungs of chronic obstructive pulmonary disease (COPD). Although we previously reported that LHX9 mRNA expression was up-regulated in AT2 cells of COPD lung tissues, it is yet to be elucidated how LHX9 is associated with the vulnerability of AT2 cells in COPD. METHODS: AT2 cells were isolated from lung tissues of 10 non-COPD subjects and 11 COPD patients. LHX9 mRNA expression was determined by quantitative RT-PCR. To identify up-stream molecules, an alveolar epithelial cell line A549 was exposed to pro-inflammatory cytokines in vitro. siRNA-mediated Lhx9 knockdown was performed to determine how Lhx9 affected the cellular viability and the cell-division cycle. RESULTS: LHX9 mRNA expression was increased in AT2 cells from COPD lung tissues, compared to those from non-COPD tissues. The airflow obstruction was independently correlated with the increase in LHX9 expression. Among several pro-inflammatory cytokines, interferon-γ was a strong inducer of LHX9 expression in A549 cells. Lhx9 was involved in the increased susceptibility to serum starvation-induced death of A549 cells. CONCLUSIONS: Our data suggest that IFN-γ predominantly increases the LHX9 expression which enhances the susceptibility to cell death. Considering the independent association of the increased LHX9 expression in AT2 cells with airflow obstruction, the IFN-γ-Lhx9 axis might contribute to the vulnerability of AT2 cells in the lungs of COPD patients.