Abstract
Increasing evidence points towards an inflammatory component underlying pulmonary hypertension. However, the conclusive characterisation of multiple inflammatory cell populations in the lung is challenging due to the complexity of marker specificity and tissue inaccessibility. We used an unbiased computational flow cytometry approach to delineate the inflammatory landscape of idiopathic pulmonary arterial hypertension (IPAH) and healthy donor lungs.Donor and IPAH samples were discriminated clearly using principal component analysis to reduce the multidimensional data obtained from single-cell flow cytometry analysis. In IPAH lungs, the predominant CD45+ cell type switched from neutrophils to CD3+ T-cells, with increases in CD4+, CD8+ and γδT-cell subsets. Additionally, diversely activated classical myeloid-derived dendritic cells (CD14−HLA-DR+CD11c+CD1a+/−) and nonclassical plasmacytoid dendritic cells (pDCs; CD14−CD11c−CD123+HLA-DR+), together with mast cells and basophils, were more abundant in IPAH samples. We describe, for the first time, the presence and regulation of two cell types in IPAH, γδT-cells and pDCs, which link innate and adaptive immunity.With our high-throughput flow cytometry with multidimensional dataset analysis, we have revealed the interactive interplay between multiple inflammatory cells is a crucial part of their integrative network. The identification of γδT-cells and pDCs in this disease potentially provides a missing link between IPAH, autoimmunity and inflammation.
Highlights
Pulmonary hypertension (PH) is characterised by severe vascular remodelling, resulting in increased pulmonary vascular resistance
Representative images of lung morphology showing classical vascular remodelling in idiopathic pulmonary arterial hypertension (IPAH) are shown in online supplementary figure S2. 21 different cell populations were analysed and separated into cells of 1) lymphoid lineage, including Band T-cells, T-cell subpopulations and natural killer (NK) cells and 2) myeloid lineage, consisting of monocytes, macrophages, mast cells, neutrophils and dendritic cells (DCs) among others
Using an unsupervised and unbiased approach we have evaluated the presence and abundance of 21 different inflammatory cell populations, thereby detailing the inflammatory landscape in healthy control lungs, and that of IPAH patients
Summary
Pulmonary hypertension (PH) is characterised by severe vascular remodelling, resulting in increased pulmonary vascular resistance. Despite the clear link between PH and dysregulation of the immune system [2], systematic analysis of immune and inflammatory cells in the lungs of PH patients is still lacking. Recruited inflammatory cells can release certain mediators that directly alter the vessel microenvironment, and recruit additional circulating inflammatory cells, which in turn further worsens disease progression. The expression of several cytokines and chemokines, such as CCL2, CCL5 or CX3CL1/fractalkine, is increased in lungs and remodelled vessels of PH patients [8,9,10]. Inflammatory cells are an important source of other mediators, such as danger molecules (HMGB1) and proteases (tryptase), which can lead to enhanced pulmonary smooth muscle cell proliferation when produced locally [7, 11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
