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Liu J, Copland DA, Clare AJ, Gorski M, Richards BT, Scott L, Theodoropoulou S, Greferath U, Cox K, Shi G, Bell OH, Ou K, Powell JLB, Wu J, Robles LM, Li Y, Nicholson LB, Coffey PJ, Fletcher EL, Guymer R, Radeke MJ, Heid IM, Hageman GS, Chan YK, Dick AD. Replenishing IRAK-M expression in retinal pigment epithelium attenuates outer retinal degeneration. Sci Transl Med 2024; 16:eadi4125. [PMID: 38838135 DOI: 10.1126/scitranslmed.adi4125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 05/14/2024] [Indexed: 06/07/2024]
Abstract
Chronic inflammation is a constitutive component of many age-related diseases, including age-related macular degeneration (AMD). Here, we identified interleukin-1 receptor-associated kinase M (IRAK-M) as a key immunoregulator in retinal pigment epithelium (RPE) that declines during the aging process. Rare genetic variants of IRAK3, which encodes IRAK-M, were associated with an increased likelihood of developing AMD. In human samples and mouse models, IRAK-M abundance in the RPE declined with advancing age or exposure to oxidative stress and was further reduced in AMD. Irak3-knockout mice exhibited an increased incidence of outer retinal degeneration at earlier ages, which was further exacerbated by oxidative stressors. The absence of IRAK-M led to a disruption in RPE cell homeostasis, characterized by compromised mitochondrial function, cellular senescence, and aberrant cytokine production. IRAK-M overexpression protected RPE cells against oxidative or immune stressors. Subretinal delivery of adeno-associated virus (AAV)-expressing human IRAK3 rescued light-induced outer retinal degeneration in wild-type mice and attenuated age-related spontaneous retinal degeneration in Irak3-knockout mice. Our data show that replenishment of IRAK-M in the RPE may redress dysregulated pro-inflammatory processes in AMD, suggesting a potential treatment for retinal degeneration.
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Affiliation(s)
- Jian Liu
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - David A Copland
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Alison J Clare
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Mathias Gorski
- Department of Genetic Epidemiology, University of Regensburg, Regensburg 93053, Germany
| | - Burt T Richards
- Sharon Eccles Steele Center for Translational Medicine, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Louis Scott
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Sofia Theodoropoulou
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Ursula Greferath
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Katherine Cox
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Gongyu Shi
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Oliver H Bell
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Kepeng Ou
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Jenna Le Brun Powell
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Jiahui Wu
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Luis Martinez Robles
- School of Cellular and Molecular Medicine, University of Bristol, Bristol BS8 1TD, UK
| | - Yingxin Li
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
| | - Lindsay B Nicholson
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
- School of Cellular and Molecular Medicine, University of Bristol, Bristol BS8 1TD, UK
| | - Peter J Coffey
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Erica L Fletcher
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Robyn Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Monte J Radeke
- Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Iris M Heid
- Department of Genetic Epidemiology, University of Regensburg, Regensburg 93053, Germany
| | - Gregory S Hageman
- Sharon Eccles Steele Center for Translational Medicine, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Ying Kai Chan
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02215, USA
| | - Andrew D Dick
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol BS8 1TD, UK
- School of Cellular and Molecular Medicine, University of Bristol, Bristol BS8 1TD, UK
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital, London EC1V 2PD, UK
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Liu J, Copland DA, Clare AJ, Gorski M, Richards BT, Scott L, Theodoropoulou S, Greferath U, Cox K, Bell OH, Ou K, Powell JLB, Wu J, Robles LM, Li Y, Nicholson LB, Coffey PJ, Fletcher EL, Guymer R, Radeke MJ, Heid IM, Hageman GS, Chan YK, Dick AD. Replenishing Age-Related Decline of IRAK-M Expression in Retinal Pigment Epithelium Attenuates Outer Retinal Degeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.27.559733. [PMID: 37808640 PMCID: PMC10557650 DOI: 10.1101/2023.09.27.559733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Unchecked, chronic inflammation is a constitutive component of age-related diseases, including age-related macular degeneration (AMD). Here we identified interleukin-1 receptor-associated kinase (IRAK)-M as a key immunoregulator in retinal pigment epithelium (RPE) that declines with age. Rare genetic variants of IRAK-M increased the likelihood of AMD. IRAK-M expression in RPE declined with age or oxidative stress and was further reduced in AMD. IRAK-M-deficient mice exhibited increased incidence of outer retinal degeneration at earlier ages, which was further exacerbated by oxidative stressors. The absence of IRAK-M disrupted RPE cell homeostasis, including compromised mitochondrial function, cellular senescence, and aberrant cytokine production. IRAK-M overexpression protected RPE cells against oxidative or immune stressors. Subretinal delivery of AAV-expressing IRAK-M rescued light-induced outer retinal degeneration in wild-type mice and attenuated age-related spontaneous retinal degeneration in IRAK-M-deficient mice. Our data support that replenishment of IRAK-M expression may redress dysregulated pro-inflammatory processes in AMD, thereby treating degeneration.
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Affiliation(s)
- Jian Liu
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - David A. Copland
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Alison J. Clare
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Mathias Gorski
- Department of Genetic Epidemiology, University of Regensburg, Regensburg, Germany
| | - Burt T. Richards
- Sharon Eccles Steele Center for Translational Medicine, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Louis Scott
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Sofia Theodoropoulou
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Ursula Greferath
- Department of Anatomy and Physiology, University of Melbourne, Victoria, Australia
| | - Katherine Cox
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Oliver H. Bell
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Kepeng Ou
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Jenna Le Brun Powell
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Jiahui Wu
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Luis Martinez Robles
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Yingxin Li
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Lindsay B. Nicholson
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Peter J. Coffey
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Erica L. Fletcher
- Department of Anatomy and Physiology, University of Melbourne, Victoria, Australia
| | - Robyn Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia
| | - Monte J. Radeke
- Neuroscience Research Institute, University of California, Santa Barbara, California, United States
| | - Iris M. Heid
- Department of Genetic Epidemiology, University of Regensburg, Regensburg, Germany
| | - Gregory S. Hageman
- Sharon Eccles Steele Center for Translational Medicine, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Ying Kai Chan
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States
| | - Andrew D. Dick
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital, London, United Kingdom
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3
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Nguyen TH, Turek I, Meehan-Andrews T, Zacharias A, Irving H. Analysis of interleukin-1 receptor associated kinase-3 (IRAK3) function in modulating expression of inflammatory markers in cell culture models: A systematic review and meta-analysis. PLoS One 2020; 15:e0244570. [PMID: 33382782 PMCID: PMC7774834 DOI: 10.1371/journal.pone.0244570] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 12/13/2020] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND IRAK3 is a critical modulator of inflammation in innate immunity. IRAK3 is associated with many inflammatory diseases, including sepsis, and is required in endotoxin tolerance to maintain homeostasis of inflammation. The impact of IRAK3 on inflammatory markers such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in cell culture models remains controversial. OBJECTIVE To analyse temporal effects of IRAK3 on inflammatory markers after one- or two-challenge interventions in cell culture models. METHODS A systematic search was performed to identify in vitro cell studies reporting outcome measures of expression of IRAK3 and inflammatory markers. Meta-analyses were performed where sufficient data were available. Comparisons of outcome measures were performed between different cell lines and human and mouse primary cells. RESULTS The literature search identified 7766 studies for screening. After screening titles, abstracts and full-texts, a total of 89 studies were included in the systematic review. CONCLUSIONS The review identifies significant effects of IRAK3 on decreasing NF-κB DNA binding activity in cell lines, TNF-α protein level at intermediate time intervals (4h-15h) in cell lines or at long term intervals (16h-48h) in mouse primary cells following one-challenge. The patterns of TNF-α protein expression in human cell lines and human primary cells in response to one-challenge are more similar than in mouse primary cells. Meta-analyses confirm a negative correlation between IRAK3 and inflammatory cytokine (IL-6 and TNF-α) expression after two-challenges.
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Affiliation(s)
- Trang Hong Nguyen
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, Victoria, Australia
| | - Ilona Turek
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, Victoria, Australia
| | - Terri Meehan-Andrews
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, Victoria, Australia
| | - Anita Zacharias
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, Victoria, Australia
| | - Helen Irving
- Department of Pharmacy and Biomedical Sciences, La Trobe Institute for Molecular Science, La Trobe University, Bendigo, Victoria, Australia
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4
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Kupferschmid BJ, Rowsey PJ, Riviera M. Characterization of Spatial Learning and Sickness Responses in Aging Rats Following Recurrent Lipopolysaccharide Administration. Biol Res Nurs 2019; 22:92-102. [PMID: 31601118 DOI: 10.1177/1099800419875824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Infections in older individuals can result in cognitive function decline, yet research is limited on how recurrent infections affect cognitive responses. Activation of the immune system results in sickness responses mediated by cytokines. This pilot study examined effects of a model of recurrent infection in aged, male Brown Norway rats on sickness responses, including spatial learning, and cytokine levels. To model initial and recurrent infection, 300 μg/kg lipopolysaccharide (LPS) or saline was administered 1/day for 2 consecutive days during 2 weeks separated by 16 days. Testing occurred for 6 days during each LPS injection week using the Morris water maze, a measure used to evaluate spatial learning. Directional heading error (DHE) and swim time latency served as spatial learning indices. Retention tests and probe trials assessed memory. Plasma cytokine levels were assessed 5 and 24 hr after each LPS injection during Week 2. While food intake and weight decreased significantly in LPS-injected rats compared to controls during Week 1, both displayed increased DHE. Despite exhibiting lessened sickness behaviors during Week 2, experimental animals still displayed spatial learning deficits. Probe trials revealed memory deficits in LPS-injected animals. Interleukin 6 level was higher in the experimental group 5 and 24 hr after LPS injection on Day 1 compared to Day 2 and higher in the experimental compared to the control group at 5 hr on Day 1. Cognitive effects were dissociated from metabolic effects in aged rats, with recurring LPS exposure resulting in persistent cognitive impairment despite decreased sickness responses. Further research with older individuals is warranted.
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Affiliation(s)
| | - Pamela J Rowsey
- School of Nursing, Adult Health Nursing, The University of North Carolina Greensboro, Greensboro, NC, USA
| | - Michael Riviera
- School of Nursing, The University of Michigan-Flint, Flint, MI, USA
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Finnell JE, Wood SK. Putative Inflammatory Sensitive Mechanisms Underlying Risk or Resilience to Social Stress. Front Behav Neurosci 2018; 12:240. [PMID: 30416436 PMCID: PMC6212591 DOI: 10.3389/fnbeh.2018.00240] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 09/25/2018] [Indexed: 12/30/2022] Open
Abstract
It has been well recognized that exposure to stress can lead to the onset of psychosocial disorders such as depression. While there are a number of antidepressant therapies currently available and despite producing immediate neurochemical alterations, they require weeks of continuous use in order to exhibit antidepressant efficacy. Moreover, up to 30% of patients do not respond to typical antidepressants, suggesting that our understanding of the pathophysiology underlying stress-induced depression is still limited. In recent years inflammation has become a major focus in the study of depression as several clinical and preclinical studies have demonstrated that peripheral and central inflammatory mediators, including interleukin (IL)-1β, are elevated in depressed patients. Moreover, it has been suggested that inflammation and particularly neuroinflammation may be a direct and immediate link in the emergence of stress-induced depression due to the broad neural and glial effects that are elicited by proinflammatory cytokines. Importantly, individual differences in inflammatory reactivity may further explain why certain individuals exhibit differing susceptibility to the consequences of stress. In this review article, we discuss sources of individual differences such as age, sex and coping mechanisms that are likely sources of distinct changes in stress-induced neuroimmune factors and highlight putative sources of exaggerated neuroinflammation in susceptible individuals. Furthermore, we review the current literature of specific neural and glial mechanisms that are regulated by stress and inflammation including mitochondrial function, oxidative stress and mechanisms of glutamate excitotoxicity. Taken together, the impetus for this review is to move towards a better understanding of mechanisms regulated by inflammatory cytokines and chemokines that are capable of contributing to the emergence of depressive-like behaviors in susceptible individuals.
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Affiliation(s)
- Julie E Finnell
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Susan K Wood
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States.,WJB Dorn Veterans Administration Medical Center, Columbia, SC, United States
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6
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Astragalus membranaceus and Salvia miltiorrhiza Ameliorate Lipopolysaccharide-Induced Acute Lung Injury in Rats by Regulating the Toll-Like Receptor 4/Nuclear Factor-Kappa B Signaling Pathway. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2018; 2018:3017571. [PMID: 29619068 PMCID: PMC5829314 DOI: 10.1155/2018/3017571] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 04/26/2017] [Accepted: 07/20/2017] [Indexed: 12/11/2022]
Abstract
Astragalus membranaceus and Salvia miltiorrhiza (AM/SM) are well used in Traditional Chinese Medicines (TCM) for nourishing Qi and activating blood circulation method. From TCM theory, the pathogenesis of acute lung injury (ALI) was determined as Qi deficiency and blood stagnation. In this study, we are aiming to investigate the protective and therapeutic effects of AM/SM on a rat model of lipopolysaccharide- (LPS-) induced ALI in rats and to elucidate potential molecular mechanisms. ALI was induced by intratracheal instillation of LPS (5 mg/kg) in Sprague–Dawley rats. SM/AM was given orally before and after LPS administration. Results demonstrated that AM/SM attenuated lung histopathological changes induced by LPS, decreased wet/dry weight ratios and protein concentrations, and inhibited the production of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in BALF. Moreover, AM/SM significantly downregulated protein and mRNA expression of toll-like receptors 4 (TLR-4), interleukin-1 receptor-associated kinase-1 (IRAK-1), and nuclear factor-kappa B (NF-κB/p65). These findings suggest that AM/SM showed protective and therapeutic effects in LPS-induced ALI rat through modulating TLR-4 signaling pathways. Nourishing Qi and activating blood circulation may be a beneficial treatment for ALI.
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Brubaker AL, Rendon JL, Ramirez L, Choudhry MA, Kovacs EJ. Reduced neutrophil chemotaxis and infiltration contributes to delayed resolution of cutaneous wound infection with advanced age. THE JOURNAL OF IMMUNOLOGY 2013; 190:1746-57. [PMID: 23319733 DOI: 10.4049/jimmunol.1201213] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Advanced age is associated with alterations in innate and adaptive immune responses, which contribute to an increased risk of infection in elderly patients. Coupled with this immune dysfunction, elderly patients demonstrate impaired wound healing with elevated rates of wound dehiscence and chronic wounds. To evaluate how advanced age alters the host immune response to cutaneous wound infection, we developed a murine model of cutaneous Staphylococcus aureus wound infection in young (3-4 mo) and aged (18-20 mo) BALB/c mice. Aged mice exhibit increased bacterial colonization and delayed wound closure over time compared with young mice. These differences were not attributed to alterations in wound neutrophil or macrophage TLR2 or FcγRIII expression, or age-related changes in phagocytic potential and bactericidal activity. To evaluate the role of chemotaxis in our model, we first examined in vivo chemotaxis in the absence of wound injury to KC, a neutrophil chemokine. In response to a s.c. injection of KC, aged mice recruited fewer neutrophils at increasing doses of KC compared with young mice. This paralleled our model of wound infection, where diminished neutrophil and macrophage recruitment was observed in aged mice relative to young mice despite equivalent levels of KC, MIP-2, and MCP-1 chemokine levels at the wound site. This reduced leukocyte accumulation was also associated with lower levels of ICAM-1 in wounds from aged mice at early time points. These age-mediated defects in early neutrophil recruitment may alter the dynamics of the inflammatory phase of wound healing, impacting macrophage recruitment, bacterial clearance, and wound closure.
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Affiliation(s)
- Aleah L Brubaker
- Burn and Shock Trauma Institute, Loyola University Chicago Health Sciences Division, Maywood, IL 60153, USA
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8
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Ha T, Liu L, Kelley J, Kao R, Williams D, Li C. Toll-like receptors: new players in myocardial ischemia/reperfusion injury. Antioxid Redox Signal 2011; 15:1875-93. [PMID: 21091074 PMCID: PMC3159106 DOI: 10.1089/ars.2010.3723] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Innate immune and inflammatory responses have been implicated in myocardial ischemia/reperfusion (I/R) injury. However, the mechanisms by which innate immunity and inflammatory response are involved in myocardial I/R have not been elucidated completely. Recent studies highlight the role of Toll-like receptors (TLRs) in the induction of innate immune and inflammatory responses. Growing evidence has demonstrated that TLRs play a critical role in myocardial I/R injury. Specifically, deficiency of TLR4 protects the myocardium from ischemic injury, whereas modulation of TLR2 induces cardioprotection against ischemic insult. Importantly, cardioprotection induced by modulation of TLRs involves activation of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway, suggesting that there is a crosstalk between TLRs and PI3K/Akt signaling pathways. In addition, TLRs also associate with other coreceptors, such as macrophage scavenger receptors in the recognition of their ligands. TLRs are also involved in the induction of angiogenesis, modulation of stem cell function, and expression of microRNA, which are currently important topic areas in myocardial I/R. Understanding how TLRs contribute to myocardial I/R injury could provide basic scientific knowledge for the development of new therapeutic approaches for the treatment and management of patients with heart attack.
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Affiliation(s)
- Tuanzhu Ha
- Department of Surgery, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA
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Dunston CR, Griffiths HR. The effect of ageing on macrophage Toll-like receptor-mediated responses in the fight against pathogens. Clin Exp Immunol 2010; 161:407-16. [PMID: 20646005 PMCID: PMC2962957 DOI: 10.1111/j.1365-2249.2010.04213.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2010] [Indexed: 02/06/2023] Open
Abstract
The cellular changes during ageing are incompletely understood yet immune system dysfunction is implicated in the age-related decline in health. The acquired immune system shows a functional decline in ability to respond to new pathogens whereas serum levels of cytokines are elevated with age. Despite these age-associated increases in circulating cytokines, the function of aged macrophages is decreased. Pathogen-associated molecular pattern receptors such as Toll-like receptors (TLRs) are vital in the response of macrophages to pathological stimuli. Here we review the evidence for defective TLR signalling in normal ageing. Gene transcription, protein expression and cell surface expression of members of the TLR family of receptors and co-effector molecules do not show a consistent age-dependent change across model systems. However, there is evidence for impaired downstream signalling events, including inhibition of positive and activation of negative modulators of TLR induced signalling events. In this paper we hypothesize that despite a poor inflammatory response via TLR activation, the ineffective clearance of pathogens by macrophages increases the duration of their activation and contributes to perpetuation of inflammatory responses and ageing.
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Affiliation(s)
- C R Dunston
- Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
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10
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Chronic pulmonary LPS tolerance induces selective immunosuppression while maintaining the neutrophilic response. Shock 2010; 33:162-9. [PMID: 19487981 DOI: 10.1097/shk.0b013e3181aa9690] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
LPS challenge causes potent activation of innate immunity. Because LPS is ubiquitously present in ambient air, repeated inhalation may lead to activation of the pulmonary immune response. If this activation is unregulated, chronic LPS inhalation would lead to persistent inflammation and organ damage. We hypothesized that the lung uses the mechanism of LPS tolerance to maintain the balance between hypoinflammatory and hyperinflammatory states. We developed a model of chronic pulmonary LPS tolerance induced by pulmonary exposure to 1 microg LPS for 4 consecutive days. Mice were challenged with 10 microg of LPS 24 h later. TNF-alpha protein was significantly decreased in the bronchoalveolar lavage fluid of tolerant versus nontolerant mice, whereas IL-6 levels were significantly increased in the tolerant group. Tolerant mice were also protected from airway hyperresponsiveness. M2 and M3 muscarinic receptor mRNA was significantly decreased in the lungs of tolerant mice, suggesting a mechanism for the decreased airway hyperresponsiveness. CXCL2 was significantly reduced in tolerant mice, but CXCL1 was equivalent between groups. No difference was seen in neutrophil recruitment to the alveolar space. Interestingly, LPS tolerance does not confer cross-tolerance to the Toll-like receptor (TLR) 2 stimulus Pam3Cys. TNF-alpha and IL-6 concentrations were significantly increased in LPS-tolerant mice challenged with Pam3Cys; however, chemokine concentrations were unaffected. Our data show that repeated LPS inhalation results in differential regulation of cytokines but does not inhibit neutrophil recruitment. This unrestricted neutrophil recruitment may represent a mechanism by which individuals may be protected from pulmonary bacterial infection and pneumonia.
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11
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Kohman RA, Crowell B, Kusnecov AW. Differential sensitivity to endotoxin exposure in young and middle-age mice. Brain Behav Immun 2010; 24:486-92. [PMID: 20025957 PMCID: PMC2826540 DOI: 10.1016/j.bbi.2009.12.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 12/02/2009] [Accepted: 12/14/2009] [Indexed: 12/27/2022] Open
Abstract
Aging can have a profound effect on the neurobehavioral response to immune activation; aged subjects are predisposed to greater deficits in performance and cognitive function in conjunction with an exaggerated neuroinflammatory response. While increased reactivity to an immune insult has been well characterized in aged subjects, the alterations that may exist by middle-age have not been thoroughly investigated. The present study compared the reactions of young (4-month) and middle-age (12-month) male BALB/c mice to an acute or repeated lipopolysaccharide (LPS) challenge(s). The data suggest that in some respects middle-aged mice are more sensitive to endotoxin exposure, as they show enhanced weight loss, splenic cytokine levels, and c-fos expression in the brain following acute LPS administration compared to younger mice. However, acute LPS exposure led to comparable decreases in locomotor activity in young and middle-aged mice. Following repeated LPS administration both age groups showed diminished behavioral and neural reactions to the final LPS challenge, indicating tolerance development. However, the immune system of the middle-aged mice was still mildly responsive to the final LPS exposure, as splenic levels of IL-1beta were significantly elevated. Collectively, the data suggest that middle-age subjects are more sensitive to an immune insult.
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Affiliation(s)
- Rachel A. Kohman
- Department of Psychology, University of Illinois, Urbana IL 61801
| | - Beth Crowell
- Department of Cell Biology and Neuroscience, Behavioral Neuroscience Program, Rutgers University, Piscataway, NJ 08854
| | - Alexander W. Kusnecov
- Department of Psychology, Behavioral Neuroscience Program, Rutgers University, Piscataway, NJ 08854, and University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854
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12
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May L, van den Biggelaar AHJ, van Bodegom D, Meij HJ, de Craen AJM, Amankwa J, Frölich M, Kuningas M, Westendorp RGJ. Adverse environmental conditions influence age-related innate immune responsiveness. IMMUNITY & AGEING 2009; 6:7. [PMID: 19480711 PMCID: PMC2697140 DOI: 10.1186/1742-4933-6-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 05/30/2009] [Indexed: 11/10/2022]
Abstract
Background- The innate immune system plays an important role in the recognition and induction of protective responses against infectious pathogens, whilst there is increasing evidence for a role in mediating chronic inflammatory diseases at older age. Despite indications that environmental conditions can influence the senescence process of the adaptive immune system, it is not known whether the same holds true for the innate immune system. Therefore we studied whether age-related innate immune responses are similar or differ between populations living under very diverse environmental conditions. Methods- We compared cross-sectional age-related changes in ex vivo innate cytokine responses in a population living under affluent conditions in the Netherlands (age 20–68 years old, n = 304) and a population living under adverse environmental conditions in Ghana (age 23–95 years old, n = 562). Results- We found a significant decrease in LPS-induced Interleukin (IL)-10 and Tumor Necrosis Factor (TNF) production with age in the Dutch population. In Ghana a similar age-related decline in IL-10 responses to LPS, as well as to zymosan, or LPS plus zymosan, was observed. TNF production, however, did not show an age-associated decline, but increased significantly with age in response to co-stimulation with LPS and zymosan. Conclusion- We conclude that the decline in innate cytokine responses is an intrinsic ageing phenomenon, while pathogen exposure and/or selective survival drive pro-inflammatory responses under adverse living conditions.
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Affiliation(s)
- Linda May
- Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands.
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Zacharioudaki V, Androulidaki A, Arranz A, Vrentzos G, Margioris AN, Tsatsanis C. Adiponectin promotes endotoxin tolerance in macrophages by inducing IRAK-M expression. THE JOURNAL OF IMMUNOLOGY 2009; 182:6444-51. [PMID: 19414798 DOI: 10.4049/jimmunol.0803694] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
High levels of plasma adiponectin are associated with low levels of inflammatory markers and cardioprotection. The mechanism via which adiponectin exerts its anti-inflammatory effect is yet unknown. In the present study, we demonstrate that globular adiponectin (gAd) induces the expression of the inactive isoform of IL-1R-associated kinases (IRAK), IRAK-M. Homologous deletion of IRAK-M in IRAK-M(-/-) mice abolished the tolerogenic properties of gAd because pretreatment of IRAK-M(-/-) macrophages with gAd did not suppress LPS-induced proinflammatory cytokine production. GAd activated the MAPKs MEK1/2 and ERK1/2 in macrophages via their upstream regulator Tpl2. Activation of ERK1/2 via Tpl2 appeared necessary for the induction of IRAK-M because gAd did not induce IRAK-M in Tpl2(-/-) macrophages or in macrophages pretreated with the MEK1/2 inhibitor UO126. In addition, activation of PI3K and Akt1 also appeared necessary for the induction of IRAK-M by gAd, because treatment of Akt1(-/-) macrophages or pretreatment of macrophages with the PI3K inhibitor wortmannin abolished gAd-induced IRAK-M expression. Analysis of IRAK-M expression in human peripheral blood cells confirmed that serum adiponectin was negatively associated with IRAK-M and responsiveness to LPS. In conclusion, our data demonstrate that IRAK-M is a major mediator of gAd-induced endotoxin tolerance in primary macrophages, expression of which depends on the activation of Tpl2/ERK and PI3K/Akt1 signaling pathways.
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Affiliation(s)
- Vassiliki Zacharioudaki
- Department of Clinical Chemistry, Graduate Program on Molecular Basis of Human Disease, School of Medicine, University of Crete, Crete, Greece
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What's new in shock, January 2009? Shock 2008; 31:1-2. [PMID: 19077876 DOI: 10.1097/shk.0b013e318190b19f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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