Inflammation
Abstract
Atopic dermatitis (AD) is a persistent skin disease typified by symptoms of dry skin and recurrent eczema. AD patients are at heightened risk for Staphylococcus aureus (S. aureus) infection. Group 2 innate lymphoid cells (ILC2s) are mainly activated by epithelial cell-derived cytokines IL-33 and involved in the pathogenesis of AD. However, little is known about the effect of skin delipidization on the epithelial cell-derived cytokines and dermal ILC2s in AD. In our study, we investigated the mechanism by which S. aureus infection modulates and exacerbates the pathogenesis of dry skin, leading to type 2 inflammation in the context of innate immunity. In vivo, we found that S. aureus infection aggravated delipidization-induced dermal IL-33 release and dermal ILC2 accumulation, which exacerbated skin inflammation. We also noticed that Il33f/fK14cre mice and Tlr2–/– mice exhibited attenuated skin inflammation. In vitro, treatment with necroptosis inhibitors reduced IL-33 release from S. aureus-infected keratinocytes. Mechanistically, we observed an increase in the necroptosis-associated kinases, MLKL and RIPK3, in S. aureus-infected mice, indicating that IL-33 release was associated with necroptotic cell death responses. Our results reveal that S. aureus infection-elicited keratinocyte necroptosis contributes to IL-33-mediated type 2 inflammation, which exacerbates the pathogenesis of dry skin.
Authors
Chia-Hui Luo, Alan Chuan-Ying Lai, Chun-Chou Tsai, Wei-Yu Chen, Yu-Shan Chang, Ethan Ja-Chen Chung, Ya-Jen Chang
Abstract
Hemorrhagic cystitis may be induced by infection, radiation therapy, medications, or may be idiopathic. Along with hemorrhagic features, symptoms include urinary urgency and frequency, dysuria (painful urination) and visceral pain. Cystitis-induced visceral pain is one of the most challenging types of pain to treat and an effective treatment would address a major unmet medical need. We assessed the efficacy of a purine nucleoside phosphorylase (PNPase) inhibitor, 8-aminoguanine (8-AG) for the treatment of hemorrhagic/ulcerative cystitis. Lower urinary tract (LUT) function and structure were assessed in adult Sprague Dawley rats, treated chronically with cyclophosphamide (CYP; sacrificed day 8) and randomized to daily oral treatment with 8-AG (begun 14 days prior to CYP induction) or its vehicle. CYP-treated rats exhibited multiple abnormalities including increased urinary frequency and neural mechanosensitivity, reduced bladder levels of inosine, urothelial inflammation/damage, and activation of spinal cord microglia, associated with pain hypersensitivity. 8-AG treatment of CYP-treated rats normalized all observed histological, structural, biochemical, and physiological abnormalities. In cystitis 8-AG improved function and reduced both pain and inflammation likely by increasing inosine, a tissue-protective purine metabolite. These findings demonstrate that 8-AG has translational potential for reducing pain and preventing bladder damage in cystitis-associated LUT dysfunctions.
Authors
Amanda Wolf-Johnston, Youko Ikeda, Irina V. Zabbarova, Anthony J. Kanai, Sheldon Bastacky, Robert Moldwin, Joel N.H. Stern, Edwin K. Jackson, Lori A. Birder
Abstract
BACKGROUND. Obesity is a multi-factorial disease with adverse health implications including insulin resistance (IR). In patients with obesity, the presence of high circulating levels of leptin, deemed hyperleptinemia, is associated with IR. Recent data in mice with diet-induced-obesity (DIO) shows a partial reduction in leptin levels improves IR. Additional animal studies demonstrate IL-4 decreases leptin levels. In rodents, resident adipose tissue (AT) eosinophils (EOS) are the main source of IL-4 and are instrumental in maintaining metabolic homeostasis. A marked reduction in AT-EOS content is observed in animal models of DIO. These observations have not been explored in humans. METHODS. We analyzed AT from individuals with obesity and age-matched lean counterparts for AT-EOS content, IL-4, circulating leptin levels and measures of IR. RESULTS. Our results showed that individuals with obesity (n=15) had a significant reduction in AT-EOS content (P<0.01), decreased AT-IL-4 gene expression (P=0.02), and decreased IL-4 plasma levels (P<0.05) in addition to expected IR (P<0.001) and hyperleptinemia (P<0.01) compared to lean subjects (n=15). AT-EOS content inversely correlated with BMI (P=0.002) and IR (P=0.005). Ex vivo AT explants and in vitro cell culture of primary, human mature adipocytes exposed to either IL-4 or EOS conditioned media produced less leptin (P<0.05). CONCLUSIONS. Our results suggested for IL-4 to act as a link between EOS, AT, and leptin production. Future studies exploring this interaction may identify a new avenue for the treatment of obesity and its complications through amelioration of hyperleptinemia. TRIAL REGISTRATION. Clinicaltrials.gov NCT02378077 & NCT04234295. FUNDING. Dr. Eleanna De Filippis received support by Arizona Department of Health Services, Arizona Biomedical Research Commission (ABRC) (ADHS14-00003606), the Katryn H. and Roger Penske Career Development Award in Endocrinology in Honor of Dr. Ian Hay, and Mayo Foundation, KL2 TR002379-02-01 CTSA UL1 TR002377 NCATS/NIH. Dr. Elizabeth A. Jacobsen received support from NIAID AI132840 and Mayo Foundation
Authors
James D. Hernandez, Ting Li, Hamza Ghannam, Cassandra M. Rau, Mia Y. Masuda, James A. Madura, Elizabeth A. Jacobsen, Eleanna De Filippis
Abstract
Intrahepatic macrophages in nonalcoholic steatohepatitis (NASH) are heterogenous and include proinflammatory recruited monocyte derived macrophages. The receptor for advanced glycation end products (RAGE) is expressed on macrophages and can be activated by damage associated molecular patterns (DAMPs) upregulated in NASH, yet the role of macrophage-specific RAGE signaling in NASH is unclear. Therefore, we hypothesized that RAGE expressing macrophages are proinflammatory and mediate liver inflammation in NASH. Compared to healthy controls, RAGE expression was increased in liver biopsies from human NASH patients. In a high -fat, -fructose, and -cholesterol (FFC)-induced murine model of NASH, RAGE expression was increased, specifically on recruited macrophages. FFC mice that received a pharmacological inhibitor of RAGE (TTP488), and myeloid-specific RAGE knockout mice (RAGE-MKO) had attenuated liver injury associated with a reduced accumulation of RAGE+ recruited macrophages. Transcriptomic analysis suggested that pathways of macrophage and T-cell activation were upregulated by FFC diet, inhibited by TTP488 treatment, and reduced in RAGE-MKO mice. Correspondingly, the secretome of ligand-stimulated bone marrow derived macrophages from RAGE-MKO mice had an attenuated capacity to activate CD8+ T cells. Our data implicate RAGE as what we propose to be a novel and potentially targetable mediator of the proinflammatory signaling of recruited macrophages in NASH.
Authors
Gopanandan Parthasarathy, Amy S. Mauer, Naresh Golla, P. Vineeth Daniel, Lily H. Kim, Guneet S. Sidhu, George W. Marek 3rd, Emilien Loeuillard, Anuradha Krishnan, Hyun Se Kim Lee, Kevin D. Pavelko, Michael Charlton, Petra Hirsova, Sumera I. Ilyas, Harmeet Malhi
Abstract
Gout commonly manifests as a painful, self-limiting inflammatory arthritis. Nevertheless, the understanding of the inflammatory and immune responses underlying gout flares and remission remains ambiguous. Here, based on single-cell RNA-Seq and an independent validation cohort, we identified the potential mechanism of gout flare, which likely involves the upregulation of HLA-DQA1+ nonclassical monocytes and is related to antigen processing and presentation. Furthermore, Tregs also play an essential role in the suppressive capacity during gout remission. Cell communication analysis suggested the existence of altered crosstalk between monocytes and other T cell types, such as Tregs. Moreover, we observed the systemic upregulation of inflammatory and cytokine genes, primarily in classical monocytes, during gout flares. All monocyte subtypes showed increased arachidonic acid metabolic activity along with upregulation of prostaglandin-endoperoxide synthase 2 (PTGS2). We also detected a decrease in blood arachidonic acid and an increase in leukotriene B4 levels during gout flares. In summary, our study illustrates the distinctive immune cell responses and systemic inflammation patterns that characterize the transition from gout flares to remission, and it suggests that blood monocyte subtypes and Tregs are potential intervention targets for preventing recurrent gout attacks and progression.
Authors
Hanjie Yu, Wen Xue, Hanqing Yu, Yaxiang Song, Xinying Liu, Ling Qin, Shu Wang, Hui Bao, Hongchen Gu, Guangqi Chen, Dake Zhao, Yang Tu, Jiafen Cheng, Liya Wang, Zisheng Ai, Dayong Hu, Ling Wang, Ai Peng
Abstract
Cachexia is a debilitating skeletal muscle wasting condition for which we currently lack effective treatments. In the context of cancer, certain chemotherapeutics cause DNA damage and cellular senescence. Senescent cells exhibit chronic activation of the transcription factor nuclear factor (NF)-κB, a known mediator of the pro-inflammatory senescence-associated secretory phenotype (SASP) and skeletal muscle atrophy. Thus, targeting NF-κB represents a logical therapeutic strategy to alleviate unintended consequences of genotoxic drugs. Herein, we show that treatment with the IKK/NF-κB inhibitor SR12343 during a course of chemotherapy reduces markers of cellular senescence and the SASP in liver, skeletal muscle, and circulation and, correspondingly, attenuates features of skeletal muscle pathology. Lastly, we demonstrate SR12343 mitigates chemotherapy-induced reductions in body weight, lean mass, fat mass, and muscle strength. These findings support senescent cells as a promising druggable target to counteract the SASP and skeletal muscle wasting in the context of chemotherapy.
Authors
Davis A. Englund, Alyssa M. Jolliffe, Gabriel J. Hanson, Zaira Aversa, Xu Zhang, Xinyi Jiang, Thomas A. White, Lei Zhang, David G. Monroe, Paul D. Robbins, Laura J. Niedernhofer, Theodore M. Kamenecka, Sundeep Khosla, Nathan K. LeBrasseur
Abstract
Plasma cell-free DNA (cfDNA), a marker of disease severity in sepsis, is a recognized driver of thromboinflammation and a potential therapeutic target. In sepsis, plasma cfDNA is mostly derived from neutrophil extracellular trap (NET) degradation. Proposed NET-directed therapeutic strategies include preventing NET formation or accelerating NET degradation. However, NET digestion liberates pathogens and releases cfDNA that promote thrombosis and endothelial cell injury. We propose an alternative strategy of cfDNA and NET stabilization with chemokine platelet factor 4 (PF4, CXCL4). We previously showed that human PF4 (hPF4) enhances NET-mediated microbial entrapment. We now show that hPF4 interferes with thrombogenicity of cfDNA and NETs by preventing their cleavage to short-fragment and single-stranded cfDNA that more effectively activates the contact pathway of coagulation. In vitro, hPF4 also inhibits cfDNA-induced endothelial tissue factor surface expression and von Willebrand factor release. In vivo, hPF4 expression reduced plasma thrombin-antithrombin (TAT) levels in animals infused with exogenous cfDNA. Following lipopolysaccharide challenge, Cxcl4–/– mice had significant elevation in plasma TAT, cfDNA, and cystatin C levels, effects prevented by hPF4 infusion. These results show that hPF4 interacts with cfDNA and NETs to limit thrombosis and endothelial injury, an observation of potential clinical benefit in the treatment of sepsis.
Authors
Anh T.P. Ngo, Abigail Skidmore, Jenna Oberg, Irene Yarovoi, Amrita Sarkar, Nate Levine, Veronica Bochenek, Guohua Zhao, Lubica Rauova, M. Anna Kowalska, Kaitlyn Eckart, Nilam S. Mangalmurti, Ann Rux, Douglas B. Cines, Mortimer Poncz, Kandace Gollomp
Abstract
Lung contusion and gastric aspiration (LC and GA) are major risk factors for developing acute respiratory distress following trauma. Hypoxia from lung injury is mainly regulated by hypoxia-inducible factor 1α (HIF-1α). Published data from our group indicate that HIF-1α regulation in airway epithelial cells (AEC) drives the acute inflammatory response following LC and GA. Metabolomic profiling and metabolic flux of Type II AEC following LC revealed marked increases in glycolytic and TCA intermediates in vivo and in vitro that were HIF-1α dependent. GLUT-1/4 expression was also increased in HIF-1α+/+ mice, suggesting that increased glucose entry may contribute to increased intermediates. Importantly, lactate incubation in vitro on Type II cells did not significantly increase the inflammatory byproduct IL-1β. Contrastingly, succinate had a direct proinflammatory effect on human small AEC by IL-1β generation in vitro. This effect was reversed by dimethylmalonate, suggesting an important role for succinate dehydrogenase in mediating HIF-1α effects. We confirmed the presence of the only known receptor for succinate binding, SUCNR1, on Type II AEC. These results support the hypothesis that succinate drives HIF-1α–mediated airway inflammation following LC. This is the first report to our knowledge of direct proinflammatory activation of succinate in nonimmune cells such as Type II AEC in direct lung injury models.
Authors
Madathilparambil V. Suresh, Sinan Aktay, George Yalamanchili, Sumeet Solanki, Dily Thazhath Sathyarajan, Manikanta Swamy Arnipalli, Subramaniam Pennathur, Krishnan Raghavendran
Abstract
Abnormal macrophage polarization is generally present in autoimmune diseases. Overwhelming M1 macrophage activation promotes the continuous progression of inflammation, which is one of the vital reasons for the development of autoimmune diseases. However, the underlying mechanism is still unclear. Here we explore the function of RFX1 in macrophage polarization by constructing colitis and lupus-like mouse models. Both in vivo and in vitro experiments confirmed that RFX1 can promote M1 and inhibit M2 macrophage polarization. Besides, we also found that RFX1 promoted DNA demethylation of macrophage polarization-related genes by increasing APOBEC3A/Apobec3 expression. Noteworthily, we identified a potential RFX1 inhibitor, adenosine diphosphate (ADP), providing a potential strategy for treating autoimmune diseases.
Authors
Shuang Yang, Pei Du, Haobo Cui, Meiling Zheng, Wei He, Xiaofei Gao, Zhi Hu, Sujie Jia, Qianjin Lu, Ming Zhao
Abstract
Modulation of the immune response to initiate and halt the inflammatory process occurs both at the site of injury as well as systemically. Due to the evolving role of cellular metabolism in regulating cell fate and function, tendon injuries which undergo normal and aberrant repair were evaluated by metabolic profiling to determine its impact on healing outcomes. Metabolomics revealed an increasing abundance of the immunomodulatory metabolite itaconate with the injury site. Subsequent single-cell RNA sequencing, molecular and metabolomic validation identified a highly mature neutrophil subtype, not macrophages, as the primary producers of itaconate following trauma. These mature itaconate-producing neutrophils were highly inflammatory, producing cytokines that promote local injury fibrosis before cycling back to the bone marrow. In the bone marrow, itaconate was shown to alter hematopoiesis, skewing progenitor cells down myeloid lineages, thereby regulating systemic inflammation. Therapeutically, exogenous itaconate was found to reduce injury site inflammation, promoting tenogenic differentiation and impairing aberrant vascularization with disease ameliorating effects. These results present an intriguing role for cycling neutrophils as a sensor of inflammation induced by injury, potentially regulating immune cell production in the bone marrow, through delivery of endogenously produced itaconate and demonstrate a therapeutic potential for exogenous itaconate following tendon injury.
Authors
Janna l. Crossley, Sonya Ostashevskaya-Gohstand, Stefano Comazzetto, Jessica S. Hook, Lei Guo, Neda Vishlaghi, Conan Juan, Lin Xu, Alexander R. Horswill, Gerta Hoxhaj, Jessica G. Moreland, Robert J. Tower, Benjamin Levi
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