Inflammation
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
Abstract
Macrophage transition from an inflammatory to reparative phenotype after tissue injury is controlled by epigenetic enzymes that regulate inflammatory gene expression. We have previously identified that the histone methyltransferase SETDB2 in macrophages drives tissue repair by repressing NF-κB–mediated inflammation. Complementary ATAC-Seq and RNA-Seq of wound macrophages isolated from mice deficient in SETDB2 in myeloid cells revealed that SETDB2 suppresses the inflammatory gene program by inhibiting chromatin accessibility at NF-κB–dependent gene promoters. We found that STAT3 was required for SETDB2 expression in macrophages, yet paradoxically, it also functioned as a binding partner of SETDB2 where it repressed SETDB2 activity by inhibiting its interaction with the NF-κB component, RELA, leading to increased RELA/NF-κB–mediated inflammatory gene expression. Furthermore, RNA-Seq in wound macrophages from STAT3-deficient mice corroborated this and revealed STAT3 and SETDB2 transcriptionally coregulate overlapping genes. Finally, in diabetic wound macrophages, STAT3 expression and STAT3/SETDB2 binding were increased. We have identified what we believe to be a novel STAT3/SETDB2 axis that modulates macrophage phenotype during tissue repair and may be an important therapeutic target for nonhealing diabetic wounds.
Authors
Kevin D. Mangum, Aaron denDekker, Qinmengge Li, Lam C. Tsoi, Amrita D. Joshi, William J. Melvin, Sonya J. Wolf, Jadie Y. Moon, Christopher O. Audu, James Shadiow, Andrea T. Obi, Rachael Wasikowski, Emily C. Barrett, Tyler M. Bauer, Kylie Boyer, Zara Ahmed, Frank M. Davis, Johann Gudjonsson, Katherine A. Gallagher
Abstract
Sepsis-induced acute lung injury (ALI) is prevalent in septic patients and has a high mortality rate. Peptidyl arginine deiminase (PADI) 2 and PADI4 play crucial roles in mediating the host’s immune response in sepsis, but their specific functions remain unclear. Our study shows that Padi2–/–Padi4–/– double knockout (DKO) improved survival, reduced lung injury, decreased bacterial load in Pseudomonas aeruginosa (PA) pneumonia-induced sepsis mice. Using single-cell RNA sequencing (scRNA-seq), we found that the deletion of Padi2 and Padi4 reduced the Nlrp3+ pro-inflammatory macrophages and fostered Chil3+ myeloid cell differentiation into anti-inflammatory macrophages. Additionally, we observed the regulatory role of NLRP3-Ym1 axis upon DKO, confirmed by Chil3 knockdown and Nlrp3 KO experiments. Thus, eliminating Padi2 and Padi4 enhances the polarization of Ym1+ M2 macrophages by suppressing NLRP3, aiding in inflammation resolution and lung tissue repair. study unveils the PADI2/PADI4-NLRP3-Ym1 pathway as a potential target in treatment of sepsis-induced ALI.
Authors
Xin Yu, Yujing Song, Tao Dong, Wenlu Ouyang, Liujiazi Shao, Chao Quan, Kyung Eun Lee, Tao Tan, Allan Tsung, Katsuo Kurabayashi, Hasan B. Alam, Mao Zhang, Jianjie Ma, Yongqing Li
Abstract
Chronic rhinosinusitis with nasal polyps (CRSwNP) is an inflammatory upper airway disease, divided into eosinophilic CRSwNP (eCRSwNP) and noneosinophilic CRSwNP (neCRSwNP) according to eosinophilic levels. Neutrophils are major effector cells in CRSwNP. but their role in different inflammatory environments remain largely unclear. We performed an integrated transcriptome analysis of polyp-infiltrating neutrophils from CRSwNP patients, using healthy donor blood as a control. Flow cytometry and in vitro studies showed that neutrophils are activated in both CRSwNP type. The scRNA-sequencing analysis demonstrated that neutrophils were classified into five functional subsets, with GBP5+ neutrophils occurring mainly in neCRSwNPs and a high proportion of CXCL8+ neutrophils in both subendotypes. GBP5+ neutrophils exhibited significant IFN-I pathway activity in neCRSwNPs. CXCL8+ neutrophils displayed increased neutrophil activation scores and mainly secrete Oncostatin M (OSM), which facilitates communication with other cells. In vitro experiments revealed that OSM could enhance IL-13- or IL-17-mediated immune responses in nasal epithelial cells and fibroblasts. Our findings revealed that neutrophils exhibited transcriptional plasticity and activation when exposed to polyp tissue and exert their proinflammatory role in the pathogenesis of CRSwNP by releasing OSM to interact with epithelial cells and fibroblasts in a manner dependent on the inflammatory milieu.
Authors
Chen Zhang, Qianqian Zhang, Jiani Chen, Han Li, Fuying Cheng, Yizhang Wang, Yingqi Gao, Yumin Zhou, Le Shi, Yufei Yang, Juan Liu, Kai Xue, Yaguang Zhang, Hongmeng Yu, Dehui Wang, Li Hu, Huan Wang, Xicai Sun
Abstract
Psoriasis is a chronic and recurrent inflammatory skin disease characterized by abnormal proliferation and differentiation of keratinocytes and activation of immune cells. However, the molecular driver that triggers this immune response in psoriatic skin remains unclear. The inflammation-related gene absent in melanoma 2 (AIM2) was identified as a susceptibility gene/locus associated with psoriasis. In this study, we investigated the role of AIM2 in the pathophysiology of psoriasis. We found elevated levels of mitochondrial DNA in patients with psoriasis, along with high expression of AIM2 in both the human psoriatic epidermis and a mouse model of psoriasis induced by topical imiquimod (IMQ) application. Genetic ablation of AIM2 reduced the development of IMQ-induced psoriasis by decreasing the production of type 3 cytokines (such as IL-17A and IL-23) and infiltration of immune cells into the inflammatory site. Furthermore, we demonstrate that IL-17A induced AIM2 expression in keratinocytes. Finally, the genetic absence of inflammasome components downstream AIM2, ASC, and caspase-1 alleviated IMQ-induced skin inflammation. Collectively, our data show that AIM2 is involved in developing psoriasis through its canonical activation.
Authors
Timna Varela Martins, Bruno Marcel Silva de Melo, Juliana E. Toller-Kawahisa, Gabriel V.L. Silva, Conceição E. Anibal-Silva, Isadora M. Paiva, Gabriel A. Publio, Marcos Henrique Rosa, Cacilda da Silva Souza, Dario S. Zamboni, Fernando Q. Cunha, Thiago M. Cunha, Bernhard Ryffel, Nicolas Riteau, José C. Alves-Filho
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