Laryngotracheal stenosis (LTS) is pathologic fibrotic narrowing of the larynx and trachea characterized by hypermetabolic fibroblasts and CD4-mediated inflammation. However, the role of CD4 T-cells in promoting LTS fibrosis is unknown. The mechanistic target of rapamycin (mTOR) signaling pathways have been shown to regulate T-cell phenotype. Here we sought to investigate the influence of mTOR signaling in CD4 T-cells on LTS pathogenesis. In this study, human LTS specimens revealed an increased population of CD4-cells expressing the activated isoform of mTOR. In a murine LTS model, targeting mTOR with systemic sirolimus and a sirolimus-eluting airway stent reduced fibrosis and TH17-cells. Selective deletion of mTOR in CD4+-cells reduced TH17-cells and attenuated fibrosis, demonstrating CD4-cells’ pathologic role in LTS. Multispectral immunofluorescence of human LTS revealed increased TH17-cells. In-vitro, TH17-cells increased collagen-1 production by LTS fibroblasts, which was prevented with sirolimus pretreatment of TH17-cells. Collectively, mTOR signaling drives pathologic CD4 T-cell phenotypes in LTS, and targeting mTOR with sirolimus is effective at treating LTS through inhibition of pro-fibrotic TH17-cells. Finally, sirolimus may be delivered locally with a drug-eluting stent, transforming clinical therapy for LTS.
Kevin M. Motz, Ioan A. Lina, Idris Samad, Michael K. Murphy, Madhavi Duvvuri, Ruth J. Davis, Alexander Gelbard, Liam Chung, Yee Chan-Li, Samuel Collins, Jonathan D. Powell, Jennifer H. Elisseeff, Maureen R. Horton, Alexander T. Hillel
DNAAF5 is a dynein motor assembly factor associated with the autosomal heterogenic recessive condition of motile cilia, primary ciliary dyskinesia (PCD). The effects of allele heterozygosity on motile cilia function are unknown. We used CRISPR-Cas9 genome editing in mice to recreate a human missense variant identified in patients with mild PCD and a second, frameshift null deletion in Dnaaf5. Litters with Dnaaf5 heteroallelic variants showed distinct missense and null gene dosage effects. Homozygosity for the null Dnaaf5 alleles was embryonic lethal. Compound heterozygous animals with the missense and null alleles showed severe disease manifesting as hydrocephalus and early lethality. However, animals homozygous for the missense mutation had improved survival, with partial preserved cilia function and motor assembly observed by ultrastructure analysis. Notably, the same variant alleles exhibited divergent cilia function across different multiciliated tissues. Proteomic analysis of isolated airway cilia from mutant mice revealed reduction in some axonemal regulatory and structural proteins not previously reported in DNAAF5 variants. While transcriptional analysis of mouse and human mutant cells showed increased expression of genes coding for axonemal proteins. Together, these findings suggest allele-specific and tissue-specific molecular requirements for cilia motor assembly that may affect disease phenotypes and clinical trajectory in motile ciliopathies.
Amjad Horani, Deepesh Gupta, Jian Xu, Huihui Xu, Lis del C. Puga Molina, Celia M. Santi, Sruthi Ramagiri, Steven K. Brennan, Jiehong Pan, Jeffrey R. Koenitzer, Tao Huang, Rachael M. Hyland, Sean P. Gunsten, Shin-Cheng Tzeng, Jennifer M. Strahle, Pleasantine Mill, Moe R. Mahjoub, Susan K. Dutcher, Steven L. Brody
Chronic lung allograft dysfunction (CLAD) is the leading cause of death in lung transplant recipients. CLAD is characterized clinically by a persistent decline in pulmonary function and histologically by the development of airway-centered fibrosis known as bronchiolitis obliterans. There are no approved therapies to treat CLAD, and the mechanisms underlying its development remain poorly understood. We performed single-cell RNA-Seq and spatial transcriptomic analysis of explanted tissues from human lung recipients with CLAD, and we performed independent validation studies to identify an important role of Janus kinase–signal transducer and activator of transcription (JAK-STAT) signaling in airway epithelial cells that contributes to airway-specific alloimmune injury. Specifically, we established that activation of JAK-STAT signaling leads to upregulation of major histocompatibility complex 1 (MHC-I) in airway basal cells, an important airway epithelial progenitor population, which leads to cytotoxic T cell–mediated basal cell death. This study provides mechanistic insight into the cell-to-cell interactions driving airway-centric alloimmune injury in CLAD, suggesting a potentially novel therapeutic strategy for CLAD prevention or treatment.
Aaditya Khatri, Jamie L. Todd, Fran L. Kelly, Andrew Nagler, Zhicheng Ji, Vaibhav Jain, Simon G. Gregory, Kent J. Weinhold, Scott M. Palmer
Emerging data indicates an association between environmental heavy metal exposure and lung disease, including lower respiratory tract infections (LRTIs). Here, we show by single cell RNA-sequencing an increase in Pparg gene expression in lung macrophages from mice exposed to cadmium and/or infected with S. pneumoniae. However, the heavy metal cadmium or infection mediated an inhibitory post-translational modification of peroxisome proliferator-activated receptor ɣ (PPARɣ) to exacerbate LRTIs. Cadmium and infection increased ERK activation to regulate PPARɣ degradation in monocyte-derived macrophages. Mice harboring a conditional deletion of Pparg in monocyte-derived macrophages had more severe S. pneumoniae infection after cadmium exposure, showed greater lung injury, and had increased mortality. Inhibition of ERK activation with BVD-523 protected mice from lung injury after cadmium exposure or infection. Moreover, subjects residing in areas of high air cadmium levels had increased cadmium concentration in their BAL fluid, increased barrier dysfunction, and showed PPARɣ inhibition that was mediated, at least in part, by ERK activation in isolated BAL cells. These observations suggest that impaired activation of PPARɣ in monocyte-derived macrophages exacerbates lung injury and the severity of LRTIs.
Jennifer L. Larson-Casey, Shanrun Liu, Jennifer M. Pyles, Suzanne E. Lapi, Komal Saleem, Veena B. Antony, Manuel Lora Gonzalez, David K. Crossman, A. Brent Carter
Mitochondrial dysfunction at birth predicts bronchopulmonary dysplasia (BPD) in extremely low birth weight (ELBW) infants. Recently, nebulized thyroid hormone (TH), given as triiodothyronine (T3) was noted to decrease pulmonary fibrosis in adult animals through improved mitochondrial function. We hypothesized that TH may have similar effects on hyperoxia-induced neonatal lung injury and mitochondrial dysfunction. To determine whether intranasal T3 decreases neonatal hyperoxic lung injury in newborn mice, T3 improves mitochondrial function in lung homogenates, neonatal murine lung fibroblasts (NMLF) and umbilical cord-derived mesenchymal stem cells (MSCs) obtained from ELBW infants, and whether neonatal hypothyroxinemia is associated with BPD in ELBW infants. Inhaled T3 (given intranasally) attenuated hyperoxia-induced lung injury and mitochondrial dysfunction in newborn mice. T3 also reduced bioenergetic deficits in UC-MSCs obtained both from infants with no/mild BPD and those with moderate/severe BPD. T3 also increased PGC1α content in lung homogenates of mice exposed to hyperoxia as well as mitochondrial potential in both NMLF and UC-MSCs. ELBW infants who died or developed moderate/severe BPD had lower TT4 compared to survivors with no/mild BPD. TH signaling and function may play a critical role in neonatal lung injury and inhaled T3 supplementation may be useful as a therapeutic strategy for BPD.
Bianca M. Vamesu, Teodora Nicola, Rui Li, Snehashis Hazra, Sadis Matalon, Naftali Kaminski, Namasivayam Ambalavanan, Jegen Kandasamy
BACKGROUND. Fibrocytes are bone marrow-derived circulating cells that traffic to the injured lungs and contribute to fibrogenesis. The mTOR inhibitor, sirolimus, inhibits fibrocyte CXCR4 expression, reducing fibrocyte traffic and attenuating lung fibrosis in animal models. We sought to test the hypothesis that short-term treatment with sirolimus reduces the concentration of CXCR4+ circulating fibrocytes in patients with idiopathic pulmonary fibrosis (IPF). METHODS. We conducted a short-term randomised double-blind placebo-controlled crossoverpilot trial to assess the safety and tolerability of sirolimus in IPF. Subjects were randomly assigned to sirolimus or placebo for approximately 6 weeks, and after a 4 week washout, assigned to the alternate treatment. Toxicity, lung function, and the concentration of circulating fibrocytes were measured before and after each treatment. RESULTS. In the 28 study subjects, sirolimus resulted in a statistically significant 35% decline in the concentration of total fibrocytes, 34% decline in CXCR4+ fibrocytes, and 42% decline in fibrocytes expressing ɑ-smooth muscle actin, but no significant change in these populations occurred on placebo. Respiratory adverse events occurred more frequently during treatment with placebo than sirolimus; the incidence of adverse events and drug tolerability did not otherwise differ during therapy with drug and placebo. Lung function was unaffected by either treatment with the exception of a small decline in gas transfer during treatment with placebo. CONCLUSIONS. As compared with placebo, short-term treatment with sirolimus resulted inreduction of circulating fibrocyte concentrations in subjects with IPF with an acceptable safety profile. TRIAL REGISTRATION. clinicaltrials.gov identifier number NCT01462006 FUNDING. NIH R01HL098329 and American Heart Association 18TPA34170486
Diana C. Gomez Manjarres, Dierdre B. Axell-House, Divya C. Patel, John Odackal, Victor Yu, Marie D. Burdick, Borna Mehrad
Cholesterol-25-hydroxylase (CH25H), the biosynthetic enzyme for 25-hydroxycholesterol (25HC), is most highly expressed in the lung, but its role in lung biology is poorly defined. Recently, we reported that Ch25h is induced in monocyte-derived macrophages recruited to the airspace during resolution of lung inflammation and that 25HC promotes Liver X Receptor (LXR)-dependent clearance of apoptotic neutrophils by these cells. Ch25h and 25HC are, however, also robustly induced by lung-resident cells during the early hours of lung inflammation, suggesting additional cellular sources and targets. Here, using Ch25h-/- mice and exogenous 25HC in lung injury models, we provide evidence that 25HC sustains pro-inflammatory cytokines in the airspace and augments lung injury, at least in part, by inducing LXR-independent endoplasmic reticulum stress and endothelial leak. Suggesting an autocrine effect in endothelium, inhaled LPS upregulates pulmonary endothelial Ch25h and non-hematopoietic Ch25h deletion is sufficient to confer lung protection. In acute respiratory distress syndrome patients, airspace 25HC and alveolar macrophage CH25H were associated with markers of microvascular leak, endothelial activation, endoplasmic reticulum stress, inflammation, and clinical severity. Taken together, our findings suggest that 25HC deriving from and acting upon different cell types in the lung communicates distinct, temporal LXR-independent and -dependent signals to regulate inflammatory homeostasis.
Jennifer H. Madenspacher, Eric D. Morrell, Jeffrey G. McDonald, Bonne M. Thompson, Yue Li, Konstantin G. Birukov, Anna A. Birukova, Renee D. Stapleton, Aidin Alejo, Peer W. Karmaus, Julie M. Meacham, Prashant Rai, Carmen Mikacenic, Mark M. Wurfel, Michael B. Fessler
Anti-CD36 antibodies have been suggested to induce transfusion-related acute lung injury (TRALI) upon blood transfusion, particularly in Asian populations. However, little is known about the pathological mechanism of anti-CD36-mediated TRALI, and potential therapies haven’t yet been identified. Here, we developed a murine model of anti-CD36-mediated TRALI to address these questions. We found that administration of mouse monoclonal antibody against CD36 (mAb GZ1) or human anti-CD36 IgG, but not GZ1 F(ab’)2 fragments, induced severe TRALI in Cd36+/+ male mice. Pre-depletion of recipient monocytes or complement, but not neutrophils or platelets, prevented the development of murine TRALI. Moreover, plasma C5a levels after TRALI induction by anti-CD36 were increased more than 3-fold, implying a critical role of complement C5 activation in the mechanism of Fc-dependent anti-CD36-mediated TRALI. Administration of GZ1 F(ab’)2, antioxidant (NAC) or C5-blocker (mAb BB5.1) before TRALI induction completely protected mice from anti-CD36-mediated TRALI. Although no significant amelioration in TRALI was observed when mice were injected with GZ1 F(ab’)2 after TRALI induction, significant improvement was achieved when mice were treated post-induction with NAC or anti-C5. Importantly, anti-C5 treatment completely rescued mice from TRALI, suggesting the potential role of existing anti-C5 drugs in the treatment of patients with TRALI caused by anti-CD36.
Da-Wei Chen, Tian Kang, Xiu-Zhang Xu, Wen-Jie Xia, Xin Ye, Yong-Bin Wu, Yao-Ri Xu, Jing Liu, Hui Ren, Jing Deng, Yang-Kai Chen, Hao-Qiang Ding, Muhammad Aslam, Wioleta M. Zelek, B. Paul Morgan, Rick Kapur, Sentot Santoso, Yong-Shui Fu
Patients with progressive fibrosing interstitial lung diseases (PF-ILDs) carry a poor prognosis and have limited therapeutic options. A hallmark feature is fibroblast resistance to apoptosis, leading to their persistence, accumulation, and excessive deposition of extracellular matrix. A complex balance of the B cell lymphoma 2 (BCL-2) protein family controlling the intrinsic pathway of apoptosis and fibroblast reliance on antiapoptotic proteins has been hypothesized to contribute to this resistant phenotype. Examination of lung tissue from patients with PF-ILD (idiopathic pulmonary fibrosis and silicosis) and mice with PF-ILD (repetitive bleomycin and silicosis) showed increased expression of antiapoptotic BCL-2 family members in α–smooth muscle actin–positive fibroblasts, suggesting that fibroblasts from fibrotic lungs may exhibit increased susceptibility to inhibition of antiapoptotic BCL-2 family members BCL-2, BCL-XL, and BCL-W with the BH3 mimetic ABT-263. We used 2 murine models of PF-ILD to test the efficacy of ABT-263 in reversing established persistent pulmonary fibrosis. Treatment with ABT-263 induced fibroblast apoptosis, decreased fibroblast numbers, and reduced lung collagen levels, radiographic disease, and histologically evident fibrosis. Our studies provide insight into how fibroblasts gain resistance to apoptosis and become sensitive to the therapeutic inhibition of antiapoptotic proteins. By targeting profibrotic fibroblasts, ABT-263 offers a promising therapeutic option for PF-ILDs.
Joseph C. Cooley, Nomin Javkhlan, Jasmine A. Wilson, Daniel G. Foster, Benjamin L. Edelman, Luis A. Ortiz, David A. Schwartz, David W.H. Riches, Elizabeth F. Redente
Type II alveolar epithelial cell (AECII) redox imbalance contributes to the pathogenesis of idiopathic pulmonary fibrosis (IPF) – a deadly disease with restricted and limited treatment options. Here, we show that expression of membrane-bound cytochrome B5 reductase 3 (CYB5R3), an enzyme critical for maintaining cellular redox homeostasis and soluble guanylate cyclase (sGC) heme iron redox state, is diminished in IPF AECII. Deficiency of CYB5R3 in AECII leads to sustained activation of the profibrotic factor TGF-β1 and increased susceptibility to lung fibrosis. We further show that CYB5R3 is a critical regulator of ERK1/2 phosphorylation and sGC-cGMP-protein kinase G axis that modulates activation of TGF-β1 signaling pathway. We demonstrate that sGC agonists (BAY 41-8543 and BAY 54-6544) are effective in reducing the pulmonary fibrotic outcomes of in vivo deficiency of CYB5R3 in AECII. Taken together, these results establish that CYB5R3 in AECII is required to maintain resilience against lung injury and fibrosis, and that therapeutic manipulation of sGC redox state could provide a basis for treating fibrotic conditions in the lung and beyond.
Marta Bueno, Jazmin Calyeca, Timur Khaliullin, Megan Miller, Diana Álvarez, Lorena Rosas, Judith Brands, Christian M. Baker, Amro Nasser, Stephanie Shulkowski, August Mathien, Nneoma O, Uzoukwu, John Sembrat, Brenton G. Mays, Kaitlin Fiedler, Scott A. Hahn, Sonia R. Salvatore, Francisco J. Schopfer, Mauricio Rojas, Peter Sandner, Adam Straub, Ana L. Mora
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