Inflammation
Abstract
Fibrosis results from excessive extracellular matrix (ECM) deposition, causing tissue stiffening and organ dysfunction. Activated fibroblasts, central to fibrosis, exhibit increased migration, proliferation, contraction, and ECM production. However, it remains unclear if the same fibroblast performs all of the processes that fall under the umbrella term of "activation". Due to fibroblast heterogeneity in connective tissues, subpopulations with specific functions may operate under distinct regulatory controls. Using a transgenic mouse model of skin fibrosis, we found that Mindin (spondin-2), secreted by Snail transgenic keratinocytes, differentially regulates fibroblast subpopulations. Mindin promotes migration and inflammatory gene expression in SCA1+ dermal fibroblasts via Fyn kinase. In contrast, it enhances contractility and collagen production in papillary CD26+ fibroblasts through c-Src signalling. Moreover, in the context of the fibrotic microenvironment of the tumour stroma, we found that differential responses of resident fibroblasts subpopulations to Mindin extend to the generation of functionally heterogeneous cancer-associated fibroblasts (CAFs). This study unveils Mindin as a key orchestrator of dermal fibroblast heterogeneity, reshaping cellular dynamics and signalling diversity in the complex landscapes of skin fibrosis and cancer.
Authors
Sunny Kataria, Isha Rana, Krithika Badarinath, Rania F. Zaarour, Gaurav Kansagara, Sultan Ahmed, Abrar Rizvi, Dyuti Saha, Binita Dam, Abhik Dutta, Ravindra K. Zirmire, Edries Yousaf Hajam, Pankaj Kumar, Akash Gulyani, Colin Jamora
Abstract
Patients with immune-mediated inflammatory diseases (IMIDs) like rheumatoid arthritis (RA) are at higher risk for severe COVID-19 and long-term complications in bone health. Emerging clinical evidence demonstrated that SARS-CoV-2 infection reduces bone turnover and promotes bone loss, but the mechanism underlying worsened bone health remains elusive. This study sought to identify specific immune mediators that exacerbated preexisting IMIDs after SARS-CoV-2 exposure. Plasma samples from 4 groups were analyzed: healthy, IMID only, COVID-19 only, and COVID-19 + IMID. Using high-throughput multiplexed proteomics, we profiled 1,500 protein biomarkers and identified 148 unique biomarkers in COVID-19 patients with IMIDs, including elevated inflammatory cytokines (e.g., IL-17F) and bone resorption markers. Long-term circulating SARS-CoV-2 ORF8, a virulence factor for COVID-19, was detected in the COVID + IMID group. RA was one of the most common IMIDs in our study. ORF8 treatment of RA-derived human osteoblasts (RA-hOBs) increased levels of inflammatory (TNF, IL6, CCL2) and bone resorption (RANKL/osteoprotegerin ratio) markers compared with healthy controls. Supernatants from ORF8-treated RA-hOBs drove the differentiation of macrophages into osteoclast-like cells. These findings suggest that SARS-CoV-2 exposure can exacerbate IMIDs through ORF8-driven inflammation and osteoclastogenesis, highlighting potential therapeutic targets for managing COVID-19–induced bone pathologies.
Authors
Ivonne Melano, Tamiris Azamor, Camila C.S. Caetano, Nikki M. Meyer, Chineme Onwubueke, Anabelle Visperas, Débora Familiar-Macedo, Gielenny M. Salem, Brandy-Lee Soos, Cassandra M. Calabrese, Youn Jung Choi, Shuyang Chen, Younho Choi, Xianfang Wu, Zilton Vasconcelos, Suzy A.A. Comhair, Karin Nielsen-Saines, Leonard H. Calabrese, M. Elaine Husni, Jae U. Jung, Nicolas S. Piuzzi, Suan-Sin Foo, Weiqiang Chen
Abstract
Despite recent advances in the treatment of thyroid eye disease thyroid-related eye disease (TED), marked gaps remain in our understanding of the underlying molecular mechanisms, particularly concerning the insulin-like growth factor-1 receptor (IGF-1R) pathway. To dissect the pathophysiology of TED, we used single-nucleus RNA-Seq to analyze orbital fat specimens from both patients with TED and matched individuals acting as controls. The analysis demonstrated a marked increase in the proportion of fibroblasts transitioning to adipogenesis in the orbital fat of patients with TED compared with that in control patients. This was associated with diverse alterations in immune cell composition. Significant alterations in the IGF-1R signaling pathway were noted between TED specimens and those from control patients, indicating a potential pathological mechanism driven by IGF-1R signaling abnormalities. Additionally, our data showed that linsitinib, a small-molecule inhibitor of IGF-1R, effectively reduced adipogenesis in TED orbital fibroblasts in vitro, suggesting its potential utility as a therapeutic agent. Our findings reveal that, beyond immune dysfunction, abnormal IGF-1R signaling leading to enhanced adipogenesis is a crucial pathogenic mechanism in TED.
Authors
Dong Won Kim, Soohyun Kim, Jeong Han, Karan Belday, Emily Li, Nicholas Mahoney, Seth Blackshaw, Fatemeh Rajaii
Abstract
Specialized memory CD4 T cells that reside long-term within tissues are critical components of immunity at portals of pathogen entry. In the lung, such tissue-resident memory (TRM) cells are activated rapidly after infection and promote local inflammation to control pathogen levels before circulating T cells can respond. However, optimal clearance of Influenza A virus can require TRM and responses by other virus-specific T cells that reach the lung only several days after their activation in secondary lymphoid organs. Whether local CD4 TRM sentinel activity can impact the efficiency of T cell activation in secondary lymphoid organs is not clear. Here, we found that recognition of antigen by influenza -primed TRM in the airways promotes more rapid migration of highly activated antigen-bearing dendritic cells to the draining lymph nodes. This in turn accelerated the priming of naive T cells recognizing the same antigen, resulting in newly activated effector T cells reaching the lungs earlier than in mice not harboring TRM. Our findings thus reveal a circuit linking local and regional immunity whereby antigen recognition by TRM improves effector T cell recruitment to the site of infection though enhancing the efficiency of antigen presentation in the draining lymph node.
Authors
Caroline M. Finn, Kunal Dhume, Eugene Baffoe, Lauren A. Kimball, Tara M. Strutt, K. Kai McKinstry
Abstract
Macrophage plays a crucial role in promoting perfusion recovery and revascularization after ischemia through anti-inflammatory polarization, a process essential for the treatment of peripheral arterial disease (PAD). Mitochondrial dynamics, particularly regulated by the fission protein DRP1, are closely linked to macrophage metabolism and inflammation. However, the role of DRP1 in reparative neovascularization remains unexplored. Here we show that DRP1 expression was increased in F4/80+ macrophages within ischemic muscle at day 3 after hindlimb ischemia (HLI), an animal model of PAD. Mice lacking Drp1 in myeloid cells exhibited impaired limb perfusion recovery, angiogenesis and muscle regeneration post-HLI. These effects were associated with increased pro-inflammatory M1-like macrophages, p-NFkB and TNFα, and reduced anti-inflammatory M2-like macrophages and p-AMPK in ischemic muscle of myeloid Drp1–/– mice. In vitro, Drp1-deficient macrophages under hypoxia serum starvation (HSS), an in vitro PAD model, demonstrated enhanced glycolysis via reducing p-AMPK as well as mitochondrial dysfunction, and excessive mitochondrial ROS production, resulting in increased pro-inflammatory M1-gene and reduced anti-inflammatory M2-gene expression. Conditioned media from HSS-treated Drp1–/– macrophages exhibited increased pro-inflammatory cytokine secretion, leading to suppressed angiogenesis in endothelial cells. Thus, macrophage DRP1 deficiency under ischemia drives pro-inflammatory metabolic reprogramming and macrophage polarization, limiting revascularization in experimental PAD.
Authors
Shikha Yadav, Vijay C. Ganta, Sudhahar Varadarajan, Vy Ong, Yang Shi, Archita Das, Dipankar Ash, Sheela Nagarkoti, Malgorzata McMenamin, Stephanie Kelley, Tohru Fukai, Masuko Ushio-Fukai
Abstract
Susceptibility to inflammatory bowel diseases (IBDs), Crohn’s disease (CD), and ulcerative colitis (UC) is linked with loss of intestinal epithelial barrier integrity and mitochondria dysfunction. Steroidogenic acute regulatory (StAR) protein-related lipid transfer (START) domain-containing protein 7 (STARD7) is a phosphatidylcholine-specific (PC-specific) lipid transfer protein that transports PC from the ER to the mitochondria, facilitating mitochondria membrane stabilization and respiration function. The aim of this study was to define the contribution of STARD7 in the regulation of the intestinal epithelial mitochondrial function and susceptibility to colitis. In silico analyses identified significantly reduced expression of STARD7 in patients with UC, which was associated with downregulation of metabolic function and a more severe disease phenotype. STARD7 was expressed in intestinal epithelial cells, and STARD7 knockdown resulted in deformed mitochondria and diminished aerobic respiration. Loss of mitochondria function was associated with reduced expression of tight junction proteins and loss of intestinal epithelial barrier integrity that could be recovered by AMPK activation. Stard7+/– mice were more susceptible to the development of DSS-induced and Il10–/– spontaneous models of colitis. STARD7 is critical for intestinal epithelial mitochondrial function and barrier integrity, and loss of STARD7 function increases susceptibility to IBD.
Authors
Jazib Uddin, Ankit Sharma, David Wu, Sunil Tomar, Varsha Ganesan, Paula E. Reichel, Lakshmi Narasimha Rao Thota, Rodolfo I. Cabrera-Silva, Sahiti Marella, Gila Idelman, Hock L. Tay, Arturo Raya-Sandino, Mack B. Reynolds, Srikanth Elesela, Yael Haberman, Lee A. Denson, Charles A. Parkos, Mary X.D. O’Riordan, Nicholas W. Lukacs, David N. O’Dwyer, Senad Divanovic, Asma Nusrat, Timothy E. Weaver, Simon P. Hogan
Abstract
Sphingosine 1-phosphate (S1P) is a lysosphingolipid with anti-atherogenic properties, but mechanisms underlying its effects remain unclear. We here investigated atherosclerosis development in cholesterol-rich diet-fed LDL receptor-deficient mice with high or low overexpression levels of S1P receptor type 1 (S1P1) in macrophages. S1P1-overexpressing macrophages showed increased activity of transcription factors PU.1, IRF8, and LXR and were skewed towards a M2-distinct phenotype characterized by enhanced production of IL-10, IL-1RA, and IL-5, increased ATP-binding cassette transporter A1- and G1-dependent cholesterol efflux, increased expression of MerTK and efferocytosis, and reduced apoptosis due to elevated Bcl6 and MafB. A similar macrophage phenotype was observed in mice administered S1P1-selective agonist KRP203. Mechanistically, the enhanced PU.1, IRF8, and LXR activity in S1P1-overexpressing macrophages led to down-regulation of the cAMP-dependent protein kinase A and activation of the signaling cascade encompassing protein kinases Akt and mTOR complex 1 (mTORC1) as well as the late endosomal/lysosomal adaptor MAPK and mTOR activator 1 (Lamtor-1). Atherosclerotic lesions in aortic roots and brachiocephalic arteries were profoundly or moderately reduced in mice with high and low S1P1 overexpression in macrophages, respectively. We conclude that S1P1 signaling polarizes macrophages towards an anti-atherogenic functional phenotype and countervails the development of atherosclerosis in mice.
Authors
Francesco Potì, Enrica Scalera, Renata Feuerborn, Josephine Fischer, Lilli Arndt, Georg Varga, Evangelia Pardali, Matthias D. Seidl, Manfred Fobker, Gerhard Liebisch, Bettina Hesse, Alexander H. Lukasz, Jan Rossaint, Beate E. Kehrel, Frank Rosenbauer, Thomas Renné, Christina Christoffersen, Manuela Simoni, Ralph Burkhardt, Jerzy-Roch Nofer
Abstract
The blood-brain barrier (BBB) is critical for maintaining brain homeostasis but is susceptible to inflammatory dysfunction. While transporter-dependent efflux of some lipophilic substrates across the BBB shows circadian variation due to rhythmic transporter expression, basal transporter–independent permeability and leakage is nonrhythmic. Whether daily timing influences BBB permeability in response to inflammation is unknown. Here, we induced systemic inflammation through repeated LPS injections either in the morning (ZT1) or evening (ZT13) under standard lighting conditions; we then examined BBB permeability to a polar molecule that is not a transporter substrate, sodium fluorescein. We observed clear diurnal variation in inflammatory BBB permeability, with a striking increase in paracellular leak across the BBB specifically following evening LPS injection. Evening LPS led to persisting glia activation as well as inflammation in the brain that was not observed in the periphery. The exaggerated evening neuroinflammation and BBB disruption were suppressed by microglial depletion or through keeping mice in constant darkness. Our data show that diurnal rhythms in microglial inflammatory responses to LPS drive daily variability in BBB breakdown and reveal time of day as a key regulator of inflammatory BBB disruption.
Authors
Jennifer H. Lawrence, Asha Patel, Melvin W. King, Collin J. Nadarajah, Richard Daneman, Erik S. Musiek
Abstract
Macrophages are required for healthy repair of the lungs following injury, but they are also implicated in driving dysregulated repair with fibrosis. How these two distinct outcomes of lung injury are mediated by different macrophage subsets is unknown. To assess this, single-cell RNA sequencing was performed on lung macrophages isolated from mice treated with lipopolysaccharide or bleomycin. Macrophages were categorized based on anatomic location (airspace versus interstitium), developmental origin (embryonic versus recruited monocyte-derived), time after inflammatory challenge, and injury model. Analysis of the integrated dataset revealed that macrophage subset clustering was driven by macrophage origin and tissue compartment rather than injury model. Gpnmb-expressing recruited macrophages that were enriched for genes typically associated with fibrosis were present in both injury models. Analogous GPNMB-expressing macrophages were identified in datasets from both fibrotic and non-fibrotic lung disease in humans. We conclude that this subset represents a conserved response to tissue injury and is not sufficient to drive fibrosis. Beyond this conserved response, we identified that recruited macrophages failed to gain resident-like programming during fibrotic repair. Overall, fibrotic versus non-fibrotic tissue repair is dictated by dynamic shifts in macrophage subset programming and persistence of recruited macrophages.
Authors
Emily M. King, Yifan Zhao, Camille M. Moore, Benjamin Steinhart, Kelsey C. Anderson, Brian Vestal, Peter K. Moore, Shannon A. McManus, Christopher M. Evans, Kara J. Mould, Elizabeth F. Redente, Alexandra L. McCubbrey, William J. Janssen
Abstract
Rheumatoid arthritis (RA) is one of the most common autoimmune disorders and is characterized by exacerbated joint inflammation that can lead to tissue remodeling and autoantigen generation. Despite the well-documented accumulation of the serine protease Granzyme B (GzmB) in the biospecimens of patients with RA, little is understood pertaining to its role in pathobiology. In the present study Tenascin-C (TN-C), a large extracellular matrix glycoprotein and an endogenous trigger of inflammation, was identified as a substrate for GzmB in RA. GzmB cleaves TN-C in vitro to generate three fragments: a 130 kDa fragment that remains anchored to the matrix, and two 70 and 30 kDa fragments that are released and solubilized. Mass spectrometry results seem to indicate that the 30 kDa fragment generated by GzmB most likely contains TN-C pro-inflammatory C-terminal fibrinogen-like domain. Soluble levels of GzmB and TN-C are also significantly elevated in the synovial fluids of RA patients compared to healthy controls, with two 70 kDa and 30 kDa soluble TN-C fragments detectable in the synovial fluids of RA patients. The molecular weights of these fragments coincide with those generated by GzmB in vitro, suggesting that GzmB also cleaves TN-C in RA patients. Granzyme K (GzmK), another member of the granzyme family, also cleaves TN-C in vitro. However, unlike GzmB, the molecular weights of TN-C fragments generated by GzmK in vitro do not correspond to fragments identified in patients. Altogether, our data supports the contribution of Granzyme B, but not Granzyme K, to RA through the cleavage of Tenascin-C.
Authors
Alexandre Aubert, Amy Liu, Martin Kao, Jenna Goeres, Katlyn C. Richardson, Lorenz Nierves, Karen Jung, Layla Nabai, Hongyan Zhao, Gertraud Orend, Roman Krawetz, Philipp F. Lange, Alastair Younger, Jonathan Chan, David J. Granville
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