Pulmonology
Abstract
The lung’s mechanosensitive immune response to alveolar overdistension impedes ventilation therapy for hypoxemic respiratory failure. Though mechanistically unclear, the prevailing hypothesis is that the immune response results when alveolar overdistension stretches alveolar macrophages (AMs). Since this hypothesis is untested in live lungs, we optically imaged live mouse alveoli to detect alveolus-adherent, sessile AMs that communicate with the alveolar epithelium through connexin43 (Cx43)-containing gap junctions. Alveolar hyperinflation did not stretch the AMs, but it increased AM Ca2+. AM-specific Cx43 deletion blocked the Ca2+ response, as well lung injury due to mechanical ventilation at high tidal volume (HTV). HTV was also inhibited by AM-targeted delivery of liposomes containing the inhibitor of endosomal Ca2+ release, Xestospongin C. We conclude, Cx43- and Ca2+-dependent AM-epithelial interactions determine the lung’s mechanosensitive immunity, providing a basis for therapy for ventilator-induced lung injury.
Authors
Liberty Mthunzi, Mohammad Islam, Galina A Gusarova, Brian Karolewski, Sunita Bhattacharya, Jahar Bhattacharya
Abstract
Chronic lung allograft dysfunction (CLAD) is the leading cause of mortality after lung transplantation, yet its molecular mechanisms remain poorly understood. To elucidate the pathogenesis of CLAD, we conducted a comprehensive single-cell transcriptomic analysis of CLAD lungs, integrating our generated datasets with approximately 1.6 million cells from 15 published studies of other fibrotic lung diseases. By applying pseudo-bulk approaches to mitigate batch effects, we identified molecular signatures specific to CLAD and those shared with idiopathic pulmonary fibrosis, COVID-19, and other fibrotic conditions. Our analysis revealed CLAD-specific cellular subsets including Fibro.AT2 cells, exhausted CD8+ T cells, and superactivated macrophages while suggesting that pathogenic keratin 17–positive, keratin 5–negative (KRT17+KRT5−) cells represent a common fibrotic mechanism across fibrotic lung diseases. Additionally, we performed donor-recipient cell deconvolution in lung allografts, uncovering distinct transcriptional programs and intercellular crosstalk between donor- and recipient-derived cells that drive allograft fibrosis. Recipient-derived stromal and immune cells showed enhanced pro-fibrotic and allograft rejection pathways compared with their donor counterparts. By leveraging insights from other fibrotic diseases to elucidate CLAD-specific mechanisms, our study provides a molecular framework for understanding CLAD pathogenesis and identifies potential therapeutic targets for this treatment-refractory condition.
Authors
Yuanqing Yan, Taisuke Kaihou, Emilia Lecuona, Xin Wu, Masahiko Shigemura, Haiying Sun, Chitaru Kurihara, Ruli Gao, Felix L. Nunez-Santana, G.R. Scott Budinger, Ankit Bharat
Abstract
SLC26A9 is an epithelial chloride channel that was identified as a genetic modifier of disease severity of cystic fibrosis (CF) and other chronic muco-obstructive lung diseases. However, data on the in vivo role of SLC26A9 function in lung health and disease remain limited. Here, we investigated the effect of genetic deletion of Slc26a9 (Slc26a9-/-) on the pulmonary phenotype of neonatal mice. We found that lack of Slc26a9 causes severe neonatal respiratory distress with high mortality. Histology, immunohistochemistry and micro-computed tomography imaging studies identified airway obstruction with MUC5B-positive mucus plugs in neonatal Slc26a9-/- mice. Bioelectric measurements demonstrated a reduced transepithelial potential difference indicative of reduced chloride secretion across tracheal explants of neonatal Slc26a9-/- compared to wild-type mice. In addition, neonatal Slc26a9-/- mice displayed hypoxic degeneration of airway epithelial cells associated with sterile neutrophilic airway inflammation. Collectively, our data show that SLC26A9-mediated chloride secretion is critical for proper mucociliary clearance, respiratory function and survival after birth, and identify a novel role of SLC26A9 in neonatal adaptation during the transition from fetal to neonatal life.
Authors
Pamela Millar-Büchner, Johanna J. Salomon, Julia Duerr, Stephan Spahn, Pinelopi Anagnostopoulou, Willi L. Wagner, Mark O. Wielpuetz, Hermann-Josef Gröne, Anita Balázs, Marcus A. Mall
Abstract
Authors
Nadir Yehya, Jacob E. Till, Nishi Srivastava, Donglan Zhang, Jason D. Christie, Erica L. Carpenter, Nilam S. Mangalmurti, Wanding Zhou
Abstract
Talc pleurodesis is highly effective for preventing recurrence of pneumothorax and pleural effusion, but can be complicated by dissemination, acute lung injury, lead exposure, and foreign body-induced chronic inflammation and pain. Our objective is to develop a safe, biodegradable, contaminant-free particle for pleurodesis. We used mouse models of pneumothorax and malignant pleural effusion to compare the efficacy and safety of pleurodesis with talc and hydroxyapatite microspheres (HAM). Intrapleural instillation of microspheres induced pleural adhesions, fibrosis and symphysis as effectively as talc, and resulted in more durable protection from experimental pneumothorax. HAM and talc both induced an osteoclastogenic, inflammatory and fibrotic response in pleural lavage cells. Intrapleural HAM was resorbed by osteoclast action over 3 months, whereas talc was not cleared. Deletion of the osteoclast effector, CTSK, diminished pleural adhesion formation and fibrosis by talc and HAM, and inhibition of osteoclastogenesis with anti-RANKL antibody delayed HAM clearance. We found no difference in activity level, feeding behavior or lung compliance between particles, but talc induced more persistent pleural inflammation. We conclude that HAM resulted in an osteoclastogenic and fibrogenic pleural response that induced pleurodesis that was more durable than talc with a superior safety profile due in part to osteoclast-mediated particle clearance.
Authors
Yusuke Tanaka, Yuki Takahashi, Yuma Shindo, Lori B. Pitstick, Steven L. Teitelbaum, Wei Zou, Xiangning Wang, Jason Woods, Kathryn A. Wikenheiser-Brokamp, Francis X. McCormack
Abstract
Bronchopulmonary dysplasia (BPD), a prevalent and chronic lung disease affecting premature newborns, results in vascular rarefaction and alveolar simplification. Although the vasculature has been recognized as a main player in this disease, the recently found capillary heterogeneity and cellular dynamics of endothelial subpopulations in BPD remain unclear. Here, we show Cap2 cells are damaged during neonatal hyperoxic injury, leading to their replacement by Cap1 cells which, in turn, significantly decline. Single cell RNA-seq identifies the activation of numerous p53 target genes in endothelial cells (ECs), including Cdkn1a (p21). While global deletion of p53 results in worsened vasculature, endothelial-specific deletion of p53 reverses the vascular phenotype and improves alveolar simplification during hyperoxia. This recovery is associated with the emergence of a transitional EC state, enriched for oxidative stress response genes and growth factors. Notably, this transitional EC gene signature is conserved in an aberrant capillary population identified in human BPD with pulmonary hypertension, underscoring the biological and clinical relevance of our findings. These results reveal a key role for p53 in maintaining endothelial lineage fidelity during pulmonary capillary repair following hyperoxic injury and highlight the critical contribution of the endothelium to BPD pathogenesis.
Authors
Lisandra Vila Ellis, Jonathan D. Bywaters, Amanda Ceas, Yun Liu, Jennifer M.S. Sucre, Jichao Chen
Abstract
High endothelial venules (HEVs) are important structures in lymph nodes (LNs) that mediate lymphocyte homing, and their dedifferentiation is a necessary step before LN metastasis. Whether vascular endothelial growth factor–related (VEGF-related) signaling, which plays an important role in LN metastasis, is involved in the dedifferentiation of HEVs remains unclear. Here, we confirmed increased expression of VEGFA, VEGFC, and VEGFD; HEV dedifferentiation; and impaired lymphocyte homing function in tumor-draining LNs (TDLNs). Furthermore, we demonstrated that tumor-secreted VEGFA induced lymphangiogenesis in TDLNs to promote premetastatic niche (PMN) formation; VEGFC promoted HEV proliferation but did not affect its lymphocyte homing function. Notably, we showed that VEGFD induced the dedifferentiation of HEVs by binding to VEGFR2 on the endothelial surface of HEVs and further impaired the lymphocyte homing function of TDLNs. Overall, we revealed that tumor-secreted VEGFD interacted with VEGFR2, induced HEV dedifferentiation, and reduced lymphocyte homing, providing potential insights for the prevention and treatment of LN metastasis.
Authors
Weichang Yang, Juan Wu, Shanshan Cai, Hongquan Xing, Jiajia Xiang, Xinyi Zhang, Xiaoyan Su, Xiaoqun Ye
Abstract
Hematopoietic stem cell transplantation (HCT) is a potentially life-saving therapy but can lead to lung injury due to chemoradiation toxicity, infection, and immune dysregulation. We previously showed that bronchoalveolar lavage (BAL) transcriptomes representing pulmonary inflammation and cellular injury can phenotype post-HCT lung injury and predict mortality. To test whether peripheral blood might be a suitable surrogate for BAL, we compared 210 paired BAL and blood transcriptomes obtained from 166 pediatric HCT patients at 27 hospitals. BAL and blood RNA abundance showed minimal correlation at the level of individual genes, gene set enrichment scores, imputed cell fractions, and T- and B-cell receptor clonotypes. Instead, we identified significant site-specific transcriptional programs. In BAL, pathways related to immunity, hypoxia, and epithelial mesenchymal transition were tightly co-expressed and linked to mortality. In contrast, in blood, expression of endothelial injury, DNA repair, and cellular metabolism pathways was associated with mortality. Integration of paired BAL and blood transcriptomes dichotomized patients into two groups with significantly different rates of hypoxia and clinical outcomes within 1 week of BAL. These findings reveal a compartmentalized injury response, where BAL and blood transcriptomes provide distinct but complementary insights into local and systemic mechanisms of post-HCT lung injury.
Authors
Emma M. Pearce, Erica Evans, Madeline Y. Mayday, Gustavo Reyes, Miriam R. Simon, Jacob Blum, Hanna Kim, Jessica Mu, Peter J. Shaw, Courtney M. Rowan, Jeffery J. Auletta, Paul L. Martin, Caitlin Hurley, Erin M. Kreml, Muna Qayed, Hisham Abdel-Azim, Amy K. Keating, Geoffrey D.E. Cuvelier, Janet R. Hume, James S. Killinger, Kamar Godder, Rabi Hanna, Christine N. Duncan, Troy C. Quigg, Paul Castillo, Nahal R. Lalefar, Julie C. Fitzgerald, Kris M. Mahadeo, Prakash Satwani, Theodore B. Moore, Benjamin Hanisch, Aly Abdel-Mageed, Dereck B. Davis, Michelle P. Hudspeth, Greg A. Yanik, Michael A. Pulsipher, Christopher C. Dvorak, Joseph L. DeRisi, Matt S. Zinter
Abstract
Asthma is characterized by exacerbated response to triggers such as allergen. While pulmonary neuroendocrine cells (PNECs), a rare population of airway epithelial cells, are essential for amplifying allergen-induced asthma response, how PNECs are regulated to achieve this role remains poorly understood. Here we show that in the adult mouse airway, inactivation of achaete-scute-like protein 1 gene in PNECs led to loss of these cells. Intriguingly, exposure of these mutants to house dust mites (HDM), a common allergen, led to reappearance of PNECs. Similarly, exposure of wild-type mice to HDM led to PNEC hyperplasia, a result of proliferation of existing PNECs and transdifferentiation from club cells. Single-cell RNA-Seq experiments revealed PNEC heterogeneity, including the emergence of an allergen-induced PNEC subtype. Notch signaling was downregulated in HDM-treated airway, and treatment with Notch agonist prevented PNEC hyperplasia. These findings together suggest that HDM-induced PNEC hyperplasia may contribute to exacerbated asthma response.
Authors
Estelle Kim, Brian K. Wells, Hannah Indralingam, Yujuan Su, Jamie Verheyden, Xin Sun
Abstract
Idiopathic pulmonary fibrosis (IPF) is a severe diffuse progressive fibrosing interstitial disease leading to respiratory failure and death in the absence of organ transplantation. Substantial evidence has confirmed the pivotal role of fibroblasts in the progression of IPF, yet effective therapeutic options are scarce. Single-cell transcriptomics profiling revealed that among the diverse fibroblast subsets, FAP1+ alveolar fibroblasts (AFs) are pivotal for the progression of IPF. On the basis of these findings, we developed FAP1-targeting chimeric antigen receptor cytotoxic effector regulatory T (CAR-cTregs) cells, which leverage the targeted killing advantage of the currently trending CAR-based immunotherapy for tumors and incorporate the immunosuppressive functions of Tregs to mitigate the inflammation caused by both the disease itself and CAR-T-cell infusion. Accordingly, CAR-cTregs were constructed to effectively eliminate FAP1+ fibroblasts in vitro. This cytotoxic effect can be abrogated by inhibitors of the granzyme-perforin pathway. In the bleomycin-induced PF model, CAR-cTregs were found to reverse fibrosis characterized by diminished recruitment of fibrocytes and improved remodeling of epithelial cells. Together, our results demonstrate that CAR-cTregs can serve as a promising therapeutic option for IPF and provide a novel strategy for treating multiple chronic inflammatory diseases by inducing both cytotoxicity and immunosuppression.
Authors
Yun-Han Jiang, Meng Zhou, Meng-Di Cheng, Sai Chen, Ying-Qiang Guo
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