Pulmonary surfactant is a lipoprotein complex lining the alveolar surface to decrease the surface tension and facilitate inspiration. Surfactant deficiency is often seen in premature infants and also children and adults with respiratory distress syndrome. Mechanical stretch of alveolar type 2 epithelial (AT2) cells during lung expansion is the primary physiological factor that stimulates surfactant secretion; however, it is unclear whether there is a mechanosensor dedicated for this process. Here we show that loss of mechanosensitive channels TMEM63A and TMEM63B resulted in atelectasis and respiratory failure in mice due to deficit of surfactant secretion. TMEM63A/B were predominantly localized at the limiting membrane of lamellar body, a lysosome-related organelle that stores pulmonary surfactant and ATP in AT2 cells. Activation of TMEM63A/B channels during cell stretch facilitated release of surfactant and ATP from lamellar bodies fused with the plasma membrane. The released ATP evoked Ca2+ signaling in AT2 cells and potentiated exocytic fusion of more lamellar bodies. Our study uncovered a vital physiological function of TMEM63 mechanosensitive channels, which makes the lung ready for the first breath at birth and maintains respiration through the life.
Gui-Lan Chen, Jing-Yi Li, Xin Chen, Jia-Wei Liu, Qian Zhang, Jie-Yu Liu, Jing Wen, Na Wang, Ming Lei, Jun-Peng Wei, Li Yi, Jia-Jia Li, Yu-Peng Ling, He-Qiang Yi, Zhenying Hu, Jingjing Duan, Jin Zhang, Bo Zeng
In a structure-function study of sulfatides, that typically stimulate type II NKT cells, we made an unexpected discovery. We compared analogues with sphingosine or phytosphingosine chains and 24-carbon acyl chains with 0-1-2 double bonds (C or pC24:0, 24:1, or 24:2). C24:1 and C24:2 sulfatide presented by CD1d monomer on plastic stimulated type II, not type I, NKT-cell hybridomas as expected. Unexpectedly, when presented by bone-marrow-derived DCs (BMDCs), C24:2 reversed specificity to stimulate type I, not type II, NKT-cell hybridomas, mimicking the corresponding βGalCer without sulfate. It induced IFNγ-dependent immunoprotection against CT26 colon-cancer lung metastases, skewed the cytokine profile, and activated cDC1s. This was abrogated by blocking lysosomal processing with bafilomycin A1, or sulfite-blocking or deletion of arylsulfatase A that cleaves off sulfate. Thus, C24:2 is unexpectedly processed in BMDCs from a type II to a type I NKT cell-stimulating ligand, promoting tumor immunity. We believe this is the first discovery of antigen processing of glycosylceramides altering the specificity for the target cell that reverses its function from stimulating type II to stimulating type I NKT cells, introducing protective functional activity in cancer. It also uncovers a new role for antigen processing, not to allow MHC loading but to alter the cell responding.
Kumiko Nishio, Lise Pasquet, Kaddy Camara, Julia DiSapio, Shingo Kato, Kevin S. Hsu, Anja Bloom, Stewart K. Richardson, Joshua A. Welsh, Tianbo Jiang, Jennifer C. Jones, Susanna Cardell, Hiroshi Watarai, Masaki Terabe, Purevdorj B. Olkhanud, Amy R. Howell, Jay A. Berzofsky
Although chronic low-grade inflammation does not cause immediate clinical symptoms, over longer term can enhance other insults or of age-dependent damage to organ systems and thereby contribute to age-related disorders, such as respiratory disorders, heart disease, metabolic disorders, autoimmunity, and cancer. However, the molecular mechanisms governing low-level inflammation are largely unknown. We discovered that Bik-deficiency causes low level inflammation even at baseline and the development of spontaneous emphysema in female but not male mice. Similarly, a single nucleotide polymorphism that reduced Bik levels was associated with increased inflammation and enhanced decline in lung function in humans. Transgenic expression of Bik in the airways of Bik-deficient mice inhibited allergen- or LPS-induced lung inflammation and reversed emphysema in female mice. Bik-deficiency increased nuclear but not cytosolic p65 levels, because Bik by modifying the BH4 domain of Bcl-2 interacted with Rpn1 and Rpn2 and enhanced proteasomal degradation of nuclear proteins. Bik-deficiency increased inflammation primarily in females because Bcl-2 and Bik levels were reduced in lung tissues and airway cells of female compared with male mice. Therefore, controlling low-grade inflammation by modifying the unappreciated role of Bik and Bcl-2 in facilitating proteasomal degradation of nuclear proteins may be crucial in treating chronic age-related diseases.
Yohannes A. Mebratu, Jane T. Jones, Congjian Liu, Zerihun H. Negasi, Mizanur Rahman, Joselyn Rojas-Quintero, George T. O'Connor, Wei Gao, Josee Dupuis, Michael H. Cho, Augusto A. Litonjua, Scott Randell, Yohannes Tesfaigzi
Altered tryptophan catabolism has been identified in inflammatory diseases like rheumatoid arthritis (RA) and spondyloarthritis (SpA), but the causal mechanisms linking tryptophan metabolites to disease are unknown. Using the collagen-induced arthritis (CIA) model we identified alterations in tryptophan metabolism, and specifically indole, that correlated with disease. We demonstrated that both bacteria and dietary tryptophan were required for disease, and indole supplementation was sufficient to induce disease in their absence. When mice with CIA on a low-tryptophan diet were supplemented with indole, we observed significant increases in serum IL-6, TNF, and IL-1β; splenic RORγt+CD4+ T cells and ex vivo collagen-stimulated IL-17 production; and a pattern of anti-collagen antibody isotype switching and glycosylation that corresponded with increased complement fixation. IL-23 neutralization reduced disease severity in indole-induced CIA. Finally, exposure of human colon lymphocytes to indole increased expression of genes involved in IL-17 signaling and plasma cell activation. Altogether, we propose a mechanism by which intestinal dysbiosis during inflammatory arthritis results in altered tryptophan catabolism, leading to indole stimulation of arthritis development. Blockade of indole generation may present a unique therapeutic pathway for RA and SpA.
Brenda J. Seymour, Brandon Trent, Brendan E. Allen, Adam J. Berlinberg, Jimmy Tangchittsumran, Widian K. Jubair, Meagan E. Chriswell, Sucai Liu, Alfredo Ornelas, Andrew Stahly, Erica E. Alexeev, Alexander S. Dowdell, Sunny L. Sneed, Sabrina Fechtner, Jennifer M. Kofonow, Charles E. Robertson, Stephanie M. Dillon, Cara C. Wilson, Robert M. Anthony, Daniel N. Frank, Sean P. Colgan, Kristine A. Kuhn
Aplasia cutis congenita (ACC) is a congenital epidermal defect of the midline scalp and has been proposed to be due to a primary keratinocyte abnormality. Why it forms mainly at this anatomic site has remained a longstanding enigma. KCTD1 mutations cause ACC, ectodermal abnormalities, and kidney fibrosis, whereas KCTD15 mutations cause ACC and cardiac outflow tract abnormalities. Here, we find that KCTD1 and KCTD15 can form multimeric complexes and can compensate for each other's loss, and that disease mutations are dominant-negative, resulting in lack of KCTD1/KCTD15 function. We demonstrate that KCTD15 is critical for cardiac outflow tract development, whereas KCTD1 regulates distal nephron function. Combined inactivation of KCTD1/KCTD15 in keratinocytes results in abnormal skin appendages, but not in ACC. Instead, KCTD1/KCTD15 inactivation in neural crest cells results in ACC linked to midline skull defects, demonstrating that ACC is not caused by a primary defect in keratinocytes but is a secondary consequence of impaired cranial neural crest cells giving rise to midline cranial suture cells that express keratinocyte-promoting growth factors. Our findings explain the clinical observations in patients with KCTD1 versus KCTD15 mutations, establish KCTD1/KCTD15 as critical regulators of ectodermal and neural crest cell functions, and define ACC as a neurocristopathy.
Jackelyn R. Raymundo, Hui Zhang, Giovanni Smaldone, Wenjuan Zhu, Kathleen E. Daly, Benjamin J. Glennon, Giovanni Pecoraro, Marco Salvatore, William A. Devine, Cecilia W. Lo, Luigi Vitagliano, Alexander G. Marneros
Itaconate has emerged as a critical immunoregulatory metabolite. Here, we examined the therapeutic potential of itaconate in atherosclerosis. We found that both itaconate and the enzyme that synthesizes it, aconitate decarboxylase 1 (Acod1, also known as “immune-responsive gene 1”/IRG1) are upregulated during atherogenesis in mice. Deletion of Acod1 in myeloid cells exacerbated inflammation and atherosclerosis in vivo and resulted in an elevated frequency of a specific subset of M1-polarized proinflammatory macrophages in the atherosclerotic aorta. Importantly, Acod1 levels were inversely correlated with clinical occlusion in atherosclerotic human aorta specimens. Treating mice with the itaconate derivative 4-ocytyl itaconate attenuated inflammation and atherosclerosis induced by high cholesterol. Mechanistically, we found that the antioxidant transcription factor, Nuclear factor erythroid-2 Related Factor 2 (Nrf2) was required for itaconate to suppress macrophage activation induced by oxidized lipids in vitro and to decrease atherosclerotic lesion areas in vivo. Overall, our work shows that itaconate suppresses atherogenesis by inducing Nrf2-dependent inhibition of proinflammatory responses in macrophages. Activation of the itaconate pathway may represent an important approach to treat atherosclerosis.
Jianrui Song, Yanling Zhang, Ryan A. Frieler, Anthony Andren, Sherri C. Wood, Daniel J. Tyrrell, Peter Sajjakulnukit, Jane C. Deng, Costas A. Lyssiotis, Richard M. Mortensen, Morgan Salmon, Daniel R. Goldstein
Several canonical translocations produce oncofusion genes that can initiate Acute Myeloid Leukemia (AML). Although each translocation is associated with unique features, the mechanisms responsible remain unclear. While proteins interacting with each oncofusion are known to be relevant for how they act, these interactions have not yet been systematically defined. To address this issue in an unbiased fashion, we fused a promiscuous biotin ligase ("TurboID") in-frame with three favorable-risk acute myeloid leukemia (AML) oncofusion cDNAs (PML::RARA, RUNX1::RUNX1T1, and CBFB::MYH11), and identified their interacting proteins in primary murine hematopoietic cells. The PML::RARA- and RUNX1::RUNX1T1-TurboID fusion proteins labeled common and unique nuclear repressor complexes, implying their nuclear localization. However, CBFB::MYH11-TurboID interacting proteins were largely cytoplasmic, probably due to an interaction of the MYH11 domain with several cytoplasmic myosin-related proteins. Using a variety of methods, we showed that the CBFB domain of CBFB::MYH11 sequesters RUNX1 in cytoplasmic aggregates; these findings were confirmed in primary human AML cells. Paradoxically, CBFB::MYH11 expression was associated with increased RUNX1/2 expression, suggesting the presence of a sensor for reduced functional RUNX1 protein, and a feedback loop that that may attempt to compensate by increasing RUNX1/2 transcription. These findings may have broad implications for AML pathogenesis.
Ryan B. Day, Julia A. Hickman, Ziheng Xu, Casey D.S. Katerndahl, Francesca Ferraro, Sai Mukund Ramakrishnan, Petra Erdmann-Gilmore, Robert W. Sprung, Yiling Mi, R. Reid Townsend, Christopher A. Miller, Timothy J. Ley
Non-alcoholic fatty liver disease (NAFLD) is prevalent in the majority of obese individuals, but in a subset, this progresses to non-alcoholic steatohepatitis (NASH) and fibrosis. The mechanisms that prevent NASH and fibrosis in the majority of NAFLD patients remain unclear. Here we report that NAD(P)H oxidase (NOX)-4 and nuclear factor erythroid 2-related factor 2 (NFE2L2) were elevated in hepatocytes early in disease progression to prevent NASH/fibrosis. Mitochondrial-derived reactive oxygen species (ROS) activated NFE2L2 to induce the expression of NOX4, which in turn generated H2O2 to exacerbate the NFE2L2 antioxidant defense response. The deletion or inhibition of NOX4 in hepatocytes decreased ROS and attenuated antioxidant defense to promote mitochondrial oxidative stress, damage proteins and lipids, diminish insulin signalling and promote cell death upon oxidant challenge. Hepatocyte NOX4 deletion in high fat fed obese mice, which otherwise develop steatosis, but not NASH, resulted in hepatic oxidative damage, inflammation and T cell recruitment to drive NASH and fibrosis, whereas NOX4 overexpression tempered the development of NASH/fibrosis in mice fed a NASH-promoting diet. Thus, mitochondrial- and NOX4-derived ROS function in concert to drive a NFE2L2 antioxidant defense response to attenuate oxidative liver damage and the progression to NASH/fibrosis in obesity.
Spencer Greatorex, Supreet Kaur, Chrysovalantou E. Xirouchaki, Pei Kee Goh, Florian Wiede, Amanda J. Genders, Melanie Tran, YaoYao Jia, Arthe Raajendiran, Wendy A. Brown, Catriona A. McLean, Junichi Sadoshima, Matthew J. Watt, Tony Tiganis
Microscopic hemorrhage is a common aspect of cancers, yet its potential role as an independent factor influencing both cancer progression and therapeutic response is largely ignored. Recognizing the essential function of macrophages in red blood cell disposal, we explored a pathway that connects intratumoral hemorrhage with the formation of cancer-promoting tumor-associated macrophages (TAMs). Using spatial transcriptomics, we found that NRF2-activated myeloid cells possessing characteristics of procancerous TAMs tend to cluster in peri-necrotic hemorrhagic tumor regions. These cells resembled anti-inflammatory erythrophagocytic macrophages. We identified heme, a red blood cell metabolite, as a pivotal microenvironmental factor steering macrophages toward protumorigenic activities. Single-cell RNA-seq and functional assays of TAMs in 3D cell culture spheroids revealed how elevated intracellular heme signals via the transcription factor NRF2 to induce cancer-promoting TAMs. These TAMs stabilized epithelial-mesenchymal transition, enhancing cancer invasiveness and metastatic potential. Additionally, NRF2-activated macrophages exhibited resistance to reprogramming by IFNγ and anti-CD40 antibodies, reducing their tumoricidal capacity. Furthermore, MC38 colon adenocarcinoma-bearing mice with NRF2 constitutively activated in leukocytes were resistant to anti-CD40 immunotherapy. Overall, our findings emphasize hemorrhage-activated NRF2 in TAMs as a driver of cancer progression, suggesting that targeting this pathway could offer new strategies to enhance cancer immunity and overcome therapy resistance.
Dominik J. Schaer, Nadja Schulthess-Lutz, Livio Baselgia, Kerstin Hansen, Raphael M. Buzzi, Rok Humar, Elena Dürst, Florence Vallelian
Acute myeloid leukemia (AML) presents a pressing medical need in that it is largely resistant to standard chemotherapy as well as modern therapeutics such as targeted therapy and immunotherapy, including anti-PD therapy. We demonstrate that Programmed Death-1 Homolog (PD-1H), an immune co-inhibitory molecule is highly expressed in blasts from the bone marrow of AML patients, while normal myeloid cell subsets and T cells have the expression of PD-1H. In studies employing syngeneic and humanized AML mouse models, overexpression of PD-1H promoted the growth of AML cells, mainly by evading T cell-mediated immune responses. Importantly, ablation of AML cell surface PD-1H by antibody blockade or genetic targeting significantly inhibited AML progression by promoting T cell activity. In addition, the genetic deletion of PD-1H from host normal myeloid cells inhibited AML progression as well and the combination of PD-1H blockade with PD-1 blockade conferred a synergistic anti-leukemia effect. Our findings provide the basis for PD-1H as an attractive therapeutic target to treat human AML.
Tae Kon Kim, Xue Han, Qianni Hu, Esten N. Vandsemb, Carly M. Fielder, Junshik Hong, Kwang Woon Kim, Emily F. Mason, R. Skipper Plowman, Jun Wang, Qi Wang, Jian-Ping Zhang, Ti Badri, Miguel F. Sanmamed, Linghua Zheng, Tianxiang Zhang, Jude Alawa, Sang Won Lee, Amer M. Zeidan, Stephanie Halene, Manoj M. Pillai, Namrata S. Chandhok, Jun Lu, Mina L. Xu, Steven D. Gore, Lieping Chen
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