Pulmonology
Abstract
Pulmonary fibrosis has been called a fibroproliferative disease but the functional importance of proliferating fibroblasts to pulmonary fibrosis has not been systematically examined. In response to alveolar injury, resting alveolar fibroblasts differentiate into fibrotic fibroblasts that express high levels of collagens. However, what role, if any, proliferation plays in the accumulation of fibrotic fibroblasts remains unclear. Through EdU incorporation, genetic lineage tracing, and single cell RNA sequencing, we resolve the proliferation dynamics of lung fibroblasts during post-injury fibrogenesis. Our data show substantial DNA replication in progeny of alveolar fibroblasts in two models of pulmonary fibrosis. By genetically labeling individual cells, we observe clonal expansion of alveolar fibroblast descendants principally in regions of fibrotic remodeling. The transcriptome of proliferating fibroblasts closely resembles that of fibrotic fibroblasts, suggesting that fibroblasts can first differentiate into fibrotic fibroblasts and then proliferate. Genetic ablation of proliferating fibroblasts and selective inhibition of cytokinesis in alveolar fibroblast descendants significantly mitigates pulmonary fibrosis and rescues lung function. Furthermore, fibroblasts in precision-cut lung slices from human fibrotic lungs exhibit higher proliferation rates than those in non-diseased lungs. This work establishes fibroblast proliferation as a critical driver of pulmonary fibrosis and suggests that specifically targeting fibroblast proliferation could be a new therapeutic strategy for fibrotic diseases.
Authors
Christopher Molina, Tatsuya Tsukui, Imran S. Khan, Xin Ren, Wenli Qiu, Michael Matthay, Paul Wolters, Dean Sheppard
Abstract
Authors
Masahiko Shigemura, Felix L. Nunez-Santana, S.Marina Casalino-Matsuda, David Kirchenbuechler, Radmila Nafikova, Fei Chen, Zhan Yu, Yuliana V. Sokolenko, Estefani Diaz, Suchitra Swaminathan, Suror Mohsin, Rizaldy P. Scott, Lynn C. Welch, Chitaru Kurihara, Emilia Lecuona, G.R. Scott Budinger, Peter H. S. Sporn, Jacob I. Sznajder, Ankit Bharat
Abstract
Authors
Nathalie Baumlin, Sumedha Gunewardena, Scott H. Randell, Frank Horrigan, Matthias Salathe
Abstract
Group 2 innate lymphoid cells (ILC2s) play a crucial role in inducing type 2 inflammation in the lungs in response to allergens. Our study investigated the regulatory mechanism of IL-10 production by ILC2s and its impact on airway hyperreactivity (AHR), focusing on the role of ICOS. We found that inhibiting ICOS in pulmonary ILC2s significantly enhances IL-10 production. The absence of ICOS reprograms ILC2 steroid metabolism, leading to increased cholesterol and cortisol biosynthesis, and subsequent Glucocorticoid receptor (GR) activation. This reprogramming regulates MAF and NFIL3 activation, promoting IL-10 production. Notably, in vivo GR inhibition or ILC2-specific GR deficiency exacerbated AHR development in multiple mouse models. We extended these findings to human ILC2s, demonstrating concordant results between murine models and human cells. Our results indicate that ICOS negatively regulates IL-10 production in ILC2s by controlling cholesterol and cortisol biosynthesis. This mechanism provides new insights into the complex interplay between ILC2s, ICOS, and glucocorticoid signaling in the context of allergic airway inflammation.
Authors
Yoshihiro Sakano, Kei Sakano, Benjamin P. Hurrell, Mohammad H. Kazemi, Xin Li, Stephen Shen, Omid Akbari
Abstract
The mechanism of neutrophilic and mixed neutrophilic-eosinophilic asthma is poorly understood. We found that extracellular DNA and nucleosomes (Nuc) were elevated in the airways from neutrophilic-eosinophilic asthma patients and correlated with bronchoalveolar lavage neutrophils. Bronchial tissue from neutrophilic-eosinophilic asthma expressed increased DNA sensor-positive cells. Intranasally administered DNA did not induce airway hyperreactivity (AHR) or any pathology but induced AHR and neutrophilic-eosinophilic inflammation when co- administered with the allergen Alternaria (Alt). Nuc alone induced anti-inflammatory/defensive genes whereas the Nuc-Alt combo increased TNF and innate cytokines. The Alt-Nuc phenotype was abolished in Cgas-/-, ALR-/-, Sting-/-, LysMCre:Stingf/f, IL7RCre:Rorαf/f and Tnfr2-/- mice. Alt, unexpectedly, played an essential role in the Nuc-induced phenotype. It abrogated Nuc-induction of anti-inflammatory genes, facilitated Nuc uptake, induced ILC2s, which, in presence of Nuc, produced high levels of TNFα and promoted neutrophilic infiltration. We established a paradigm where allergens inhibit the anti-inflammatory effects of DNA/Nuc and facilitate STING-TNFα-driven neutrophilic-eosinophilic inflammation in asthma.
Authors
Anand Sripada, Divya Verma, Rangati Varma, Kapil Sirohi, Carolyn Kwiat, Mohini Pathria, Mukesh Verma, Anita Sahu, Vamsi P. Guntur, Laurie A. Manka, Brian Vestal, Camille M. Moore, Richard J. Martin, Magdalena M. Gorska, John Cambier, Andrew Getahun, Rafeul Alam
Abstract
Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease characterized by impaired fibroblast clearance and excessive extracellular matrix (ECM) protein production. Wilms' Tumor 1 (WT1), a transcription factor, is selectively upregulated in IPF fibroblasts. However, the mechanisms by which WT1 contributes to fibroblast accumulation and ECM production remain unknown. Here, we investigated the heterogeneity of WT1-expressing mesenchymal cells using single-nucleus RNA sequencing of distal lung tissues from IPF patients and control donors. WT1 was selectively upregulated in a subset of IPF fibroblasts that co-expressed several pro-survival and ECM genes. The results of both loss-of-function and gain-of-function studies are consistent with a role for WT1 as a positive regulator of pro-survival genes to impair apoptotic clearance and promote ECM production. Fibroblast-specific overexpression of WT1 augmented fibroproliferation, myofibroblast accumulation, and ECM production during bleomycin-induced pulmonary fibrosis in young and aged mice. Together, these findings suggest that targeting WT1 is a promising strategy for attenuating fibroblast expansion and ECM production during fibrogenesis.
Authors
Harshavardhana H. Ediga, Chanukya P. Vemulapalli, Vishwaraj Sontake, Pradeep K. Patel, Hikaru Miyazaki, Dimitry Popov, Martin B. Jensen, Anil G. Jegga, Steven K. Huang, Christoph Englert, Andreas Schedl, Nishant Gupta, Francis X. McCormack, Satish K. Madala
PIEZO1 mediates mechanical reprogramming of neutrophils for proangiogenic specialization in the lung
Abstract
Neutrophils are the most abundant immune cells that constantly patrol or marginate inside vascular beds to support immune homeostasis. The extent to which neutrophils undergo reprogramming in response to the changes in vascular architecture and the resultant biological implications of such adaptations remain unclear. Here, we performed intravital imaging and transcriptional profiling to investigate neutrophil behavior across different tissues. Our findings revealed that neutrophils had significant deformability and spontaneous calcium signaling while navigating through the narrow pulmonary vessels. Pulmonary neutrophils exhibited unique transcriptional profiles and were specialized for proangiogenic functions. We found that the mechanosensitive ion channel Piezo-type mechanosensitive ion channel component 1 (PIEZO1) was essential for neutrophil reprogramming. Deletion of Piezo1 in neutrophils ablated the lung-specific proangiogenic transcriptional signature and impaired capillary angiogenesis in both physiological and pathological conditions. Collectively, these data show that mechanical adaptation of neutrophils within the pulmonary vasculature drives their reprogramming in the lungs and promotes pulmonary vascular homeostasis.
Authors
Jin Wang, Wenying Zhao, Wenjuan Bai, Dong Dong, Hui Wang, Xin Qi, Ajitha Thanabalasuriar, Youqiong Ye, Tian-le Xu, Hecheng Li, Paul Kubes, Bin Li, Jing Wang
Abstract
Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease characterized by the excessive accumulation of activated myofibroblasts that deposit extracellular matrix (ECM) protein, leading to progressive scar formation and mechanical stress. However, the cellular origin and fate of myofibroblasts remain controversial, and the mechanisms by which myofibroblasts sense mechanical cues in the lung are unclear. Here, we report that periostin (Postn) is a reliable and distinctive marker for pulmonary myofibroblasts, while ablation of Postn+ myofibroblasts after injury ameliorated lung fibrosis. PIEZO1 was highly expressed in Postn+ myofibroblast and played a vital role in mechanoactivation of Postn+ myofibroblast and development of lung fibrosis. Conditional deletion of Piezo1 in Postn+ myofibroblasts significantly inhibited lung fibrosis by suppressing myofibroblast activation and proliferation. Loss of Piezo1 led to disruption of actin organization and prevention of Yap/Taz nuclear localization, thus shifting the myofibroblasts from a proliferative state into a stressed and apoptotic state. Furthermore, myofibroblast-specific Yap/Taz deletion fully recapitulated the protective phenotypes of myofibroblast-Piezo1–KO mice. These findings show that periostin marks pulmonary myofibroblasts, and that PIEZO1-mediated mechanosensation is essential for myofibroblast activation in the lung. Targeting PIEZO1 in the periostin-expressing cells is a novel therapeutic option to interfere with fibrotic diseases such as IPF .
Authors
Liran Xu, Ting Li, Yapeng Cao, Yu He, Zehua Shao, Siyu Liu, Bianbian Wang, Ailing Su, Huijing Tian, Yongxin Li, Guozheng Liang, Changhe Wang, John Shyy, Ying Xiong, Fangyuan Chen, Jason X.J. Yuan, Junjun Liu, Bin Zhou, Nina Wettschureck, Stefan Offermanns, Yang Yan, Zuyi Yuan, Shengpeng Wang
Abstract
Weight loss medications are emerging candidates for pharmacotherapy of sleep disordered breathing (SDB). A melanocortin receptor 4 (MC4R) agonist, setmelanotide (SET), is used to treat obesity caused by abnormal melanocortin and leptin signaling. We hypothesized that SET can treat SDB in diet induced obese mice. We performed a proof-of-concept randomized crossover trial of a single dose of SET vs vehicle and a two-week daily SET vs vehicle trial, examined co-localization of Mc4r mRNAs with markers of CO2 sensing neurons Phox2b and neuromedin-B in the brainstem, and expressed Cre-dependent designer receptors exclusively activated by designer drugs or caspase in obese Mc4r-Cre mice. SET increased minute ventilation across sleep/wake states, enhanced the hypercapnic ventilatory response (HCVR) and abolished apneas during sleep. Phox2b+ neurons in the nucleus of the solitary tract (NTS) and the parafacial region expressed Mc4r. Chemogenetic stimulation of the MC4R+ neurons in the parafacial region, but not in the NTS, augmented HCVR without any changes in metabolism. Caspase elimination of the parafacial MC4R+ neurons abolished effects of SET on HCVR. Parafacial MC4R+ neurons projected to the respiratory pre-motor neurons retrogradely labeled from C3-C4. In conclusion, MC4R agonists enhance the HCVR and treat SDB by acting on the parafacial MC4R+ neurons.
Authors
Mateus R. Amorim, Noah R. Williams, O Aung, Melanie Alexis Ruiz, Frederick Anokye-Danso, Junia Lara de Deus, Jiali Xiong, Olga Dergacheva, Shannon Bevans-Fonti, Sean M. Lee, Jeffrey S Berger, Mark N. Wu, Rexford S. Ahima, David Mendelowitz, Vsevolod Y. Polotsky
Abstract
Tissue regenerative responses involve complex interactions between resident structural and immune cells. Recent reports indicate that accumulation of senescent cells during injury repair contributes to pathological tissue fibrosis. Using tissue-based spatial transcriptomics and proteomics, we identified upregulation of the immune checkpoint protein, cytotoxic T-lymphocyte associated protein 4 (CTLA4) on CD8+ T cells adjacent to regions of active fibrogenesis in human idiopathic pulmonary fibrosis (IPF) and in a murine model of repetitive bleomycin lung injury model of persistent fibrosis. In humanized CTLA4 knock-in mice, treatment with ipilimumab, an FDA-approved drug that targets CTLA4, resulted in accelerated lung epithelial regeneration and diminished fibrosis from repetitive bleomycin injury. Ipilimumab treatment resulted in the expansion of Cd3e+ T cells, diminished accumulation of senescent cells, and robust expansion of type 2 alveolar epithelial cells, facultative progenitor cells of the alveolar epithelium. Ex-vivo activation of isolated CTLA4-expressing CD8+ cells from mice with established fibrosis resulted in enhanced cytolysis of senescent cells, suggesting that impaired immune-mediated clearance of these cells contribute to persistence of lung fibrosis in this murine model. Our studies support the concept that endogenous immune surveillance of senescent cells may be essential in promoting tissue regenerative responses that facilitate the resolution of fibrosis.
Authors
Santosh Yadav, Muralidharan Anbalagan, Shamima Khatun, Devadharshini Prabhakaran, Justin Manges, Yasuka Matsunaga, James B. McLachlan, Joseph A. Lasky, Jay Kolls, Victor J. Thannickal
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)