Human pericytes adopt myofibroblast properties in the microenvironment of the IPF lung
Parid Sava, … , Erica L. Herzog, Anjelica L. Gonzalez
Parid Sava, … , Erica L. Herzog, Anjelica L. Gonzalez
Published December 21, 2017; First published December 21, 2017
Citation Information: JCI Insight. 2017;2(24):e96352. https://doi.org/10.1172/jci.insight.96352.
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Research Article Cell biology Vascular biology

Human pericytes adopt myofibroblast properties in the microenvironment of the IPF lung

Abstract

Idiopathic pulmonary fibrosis (IPF) is a fatal disease of unknown etiology characterized by a compositionally and mechanically altered extracellular matrix. Poor understanding of the origin of α-smooth muscle actin (α-SMA) expressing myofibroblasts has hindered curative therapies. Though proposed as a source of myofibroblasts in mammalian tissues, identification of microvascular pericytes (PC) as contributors to α-SMA–expressing populations in human IPF and the mechanisms driving this accumulation remain unexplored. Here, we demonstrate enhanced detection of α-SMA+ cells coexpressing the PC marker neural/glial antigen 2 in the human IPF lung. Isolated human PC cultured on decellularized IPF lung matrices adopt expression of α-SMA, demonstrating that these cells undergo phenotypic transition in response to direct contact with the extracellular matrix (ECM) of the fibrotic human lung. Using potentially novel human lung–conjugated hydrogels with tunable mechanical properties, we decoupled PC responses to matrix composition and stiffness to show that α-SMA+ PC accumulate in a mechanosensitive manner independent of matrix composition. PC activated with TGF-β1 remodel the normal lung matrix, increasing tissue stiffness to facilitate the emergence of α-SMA+ PC via MKL-1/MTRFA mechanotranduction. Nintedanib, a tyrosine-kinase inhibitor approved for IPF treatment, restores the elastic modulus of fibrotic lung matrices to reverse the α-SMA+ phenotype. This work furthers our understanding of the role that microvascular PC play in the evolution of IPF, describes the creation of an ex vivo platform that advances the study of fibrosis, and presents a potentially novel mode of action for a commonly used antifibrotic therapy that has great relevance for human disease.

Authors

Parid Sava, Anand Ramanathan, Amelia Dobronyi, Xueyan Peng, Huanxing Sun, Adrian Ledesma-Mendoza, Erica L. Herzog, Anjelica L. Gonzalez

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Figure 5

Effects of TGF-β1 induced lung matrix stiffening and increased α-SMA expression are reversed by nintedanib treatment.

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Effects of TGF-β1 induced lung matrix stiffening and increased α-SMA exp...
PC were cultured on glass, activated with TGF-β1 for 28 days, and treated with nintedanib for 7 days. (A) Immunofluorescence images of collagen I (green) and fibronectin (red). (B–D) Matrix deposition was quantified using immunoblotting (n = 7), and (E) fibrotic lesions were quantified from images (n ≥ 10) at day 28 (represented as mean ± SEM, Student t test with Bonferroni post-test, *P < 0.05 versus TGF-β1). (F) α-SMA and (G) vimentin expression, quantified using flow cytometry (presented as mean fold increase over protein expression of cells cultured on low-stiffness healthy lung ± SEM) (H) were confirmed using immunoblotting (n ≥ 10). Black lines used to designate samples run in same gel but in noncontiguous lanes. (I) PC were cultured on decellularized control lung with TGF-β1 activation for 28 days and treated with nintedanib for 7 days. Matrix deposition was evaluated by Masson’s trichrome and Picrosirius red staining. (J) Mean Young’s Moduli ± SEM of the decellularized lung were determined using an Instron5848 at 20% strain (Student t test with Bonferroni post-test ,*P < 0.05 versus TGF-β1, n = 7–9). (K) α-SMA expression was evaluated using IHC and (L) spatial density of α-SMA+ myofibroblasts was quantified (mean ± SEM) from representative α-SMA IHC images (Student t test with Bonferroni post-test, *P < 0.05 versus TGF-β1, n = 4–6).