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Stahel PF, Weckbach S, Huber-Lang MS, Stahel VP, Barnum SR. Editorial: The impact of COVID-19 on immune system-related complications in surgical patients. Front Surg 2023; 10:1132752. [PMID: 36793320 PMCID: PMC9923122 DOI: 10.3389/fsurg.2023.1132752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 01/06/2023] [Indexed: 01/31/2023] Open
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Hao X, Li Z, Li W, Katz J, Michalek SM, Barnum SR, Pozzo-Miller L, Saito T, Saido TC, Wang Q, Roberson ED, Zhang P. Periodontal Infection Aggravates C1q-Mediated Microglial Activation and Synapse Pruning in Alzheimer's Mice. Front Immunol 2022; 13:816640. [PMID: 35178049 PMCID: PMC8845011 DOI: 10.3389/fimmu.2022.816640] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/11/2022] [Indexed: 12/24/2022] Open
Abstract
Periodontitis is a dysbiotic infectious disease that leads to the destruction of tooth supporting tissues. There is increasing evidence that periodontitis may affect the development and severity of Alzheimer's disease (AD). However, the mechanism(s) by which periodontal infection impacts the neurodegenerative process in AD remains unclear. In the present study, using an amyloid precursor protein (APP) knock-in (App KI) AD mouse model, we showed that oral infection with Porphyromonas gingivalis (Pg), a keystone pathogen of periodontitis, worsened behavioral and cognitive impairment and accelerated amyloid beta (Aβ) accumulation in AD mice, thus unquestionably and significantly aggravating AD. We also provide new evidence that the neuroinflammatory status established by AD, is greatly complicated by periodontal infection and the consequential entry of Pg into the brain via Aβ-primed microglial activation, and that Pg-induced brain overactivation of complement C1q is critical for periodontitis-associated acceleration of AD progression by amplifying microglial activation, neuroinflammation, and tagging synapses for microglial engulfment. Our study renders support for the importance of periodontal infection in the innate immune regulation of AD and the possibility of targeting microbial etiology and periodontal treatment to ameliorate the clinical manifestation of AD and lower AD prevalence.
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Barnum SR, Bubeck D, Schein TN. Soluble Membrane Attack Complex: Biochemistry and Immunobiology. Front Immunol 2020; 11:585108. [PMID: 33240274 PMCID: PMC7683570 DOI: 10.3389/fimmu.2020.585108] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
The soluble membrane attack complex (sMAC, a.k.a., sC5b-9 or TCC) is generated on activation of complement and contains the complement proteins C5b, C6, C7, C8, C9 together with the regulatory proteins clusterin and/or vitronectin. sMAC is a member of the MACPF/cholesterol-dependent-cytolysin superfamily of pore-forming molecules that insert into lipid bilayers and disrupt cellular integrity and function. sMAC is a unique complement activation macromolecule as it is comprised of several different subunits. To date no complement-mediated function has been identified for sMAC. sMAC is present in blood and other body fluids under homeostatic conditions and there is abundant evidence documenting changes in sMAC levels during infection, autoimmune disease and trauma. Despite decades of scientific interest in sMAC, the mechanisms regulating its formation in healthy individuals and its biological functions in both health and disease remain poorly understood. Here, we review the structural differences between sMAC and its membrane counterpart, MAC, and examine sMAC immunobiology with respect to its presence in body fluids in health and disease. Finally, we discuss the diagnostic potential of sMAC for diagnostic and prognostic applications and potential utility as a companion diagnostic.
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Stahel PF, Barnum SR. Complement Inhibition in Coronavirus Disease (COVID)-19: A Neglected Therapeutic Option. Front Immunol 2020; 11:1661. [PMID: 32733489 PMCID: PMC7358522 DOI: 10.3389/fimmu.2020.01661] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 06/22/2020] [Indexed: 01/08/2023] Open
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Vickers A, Donnelly JP, Moore JX, Barnum SR, Schein TN, Wang HE. Epidemiology of lumbar punctures in hospitalized patients in the United States. PLoS One 2018; 13:e0208622. [PMID: 30543645 PMCID: PMC6292631 DOI: 10.1371/journal.pone.0208622] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 11/20/2018] [Indexed: 11/18/2022] Open
Abstract
Objectives Lumbar puncture (LP) is an important technique for assessing and treating neurological symptoms. The objective of this study was to describe the characteristics of diagnostic lumbar punctures performed on hospitalized patients in the United States. Methods We analyzed data from the 2010 National Inpatient Sample (NIS) and the National Emergency Department Survey (NEDS). We included patients treated in the Emergency Department (ED) as well as those admitted to an inpatient bed through the ED. We identified patients undergoing LPs from ICD-9 procedural code 03.31 and CPT code 62270. We generated nationally weighted estimates of the total number of LPs. We also assessed patient and hospital characteristics of cases undergoing LP. Results Of an estimated 135 million hospitalizations (ED + admission, or ED only), there were an estimated 362,718 LPs (331,248–394,188), including 273,612 (251,850–295,375) among adults and 89,106 (71,870–106,342) among children (<18 years old). Of the 362,718 LPs, 136,764 (122,117–151,410) were performed in the ED without admission. The most common conditions associated with LP among children were fever of unknown origin, meningitis, seizures and other perinatal conditions. The most common conditions associated with LP among adults were headache and meningitis. Conclusions Lumbar Puncture remains an important procedure for diagnostic and therapeutic uses in United States Hospitals.
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Anderson AM, Schein TN, Kalapila A, Lai L, Waldrop-Valverde D, Moore RC, Franklin D, Letendre SL, Barnum SR. Soluble membrane attack complex in the blood and cerebrospinal fluid of HIV-infected individuals, relationship to HIV RNA, and comparison with HIV negatives. J Neuroimmunol 2017; 311:35-39. [PMID: 28774464 DOI: 10.1016/j.jneuroim.2017.07.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 12/14/2022]
Abstract
The soluble membrane attack complex (sMAC) represents the terminal product of the complement cascade. We enrolled 47 HIV+ adults (12 of whom underwent a second visit at least 24weeks after starting therapy) as well as 11 HIV negative controls. At baseline, cerebrospinal fluid (CSF) sMAC was detectable in 27.7% of HIV+ individuals. CSF sMAC correlated with CSF HIV RNA levels and was more likely to be detectable in HIV+ individuals on cART compared to HIV negative controls. In HIV+ participants, there were negative association trends between sMAC and neurocognitive performance but these did not reach statistical significance.
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Barnum SR. Therapeutic Inhibition of Complement: Well Worth the Risk. Trends Pharmacol Sci 2017; 38:503-505. [PMID: 28413098 DOI: 10.1016/j.tips.2017.03.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 03/23/2017] [Indexed: 01/17/2023]
Abstract
Complement is an integral part of the immune system and protects against infection. Complement-mediated immunopathology in many autoimmune diseases and syndromes has led to the therapeutic targeting of complement and to questions around the safety of complement inhibition. Here; I examine and clarify the risks associated with complement therapeutics.
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Stokowska A, Atkins AL, Morán J, Pekny T, Bulmer L, Pascoe MC, Barnum SR, Wetsel RA, Nilsson JA, Dragunow M, Pekna M. Complement peptide C3a stimulates neural plasticity after experimental brain ischaemia. Brain 2016; 140:353-369. [PMID: 27956400 DOI: 10.1093/brain/aww314] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 10/19/2016] [Accepted: 10/20/2016] [Indexed: 11/12/2022] Open
Abstract
Ischaemic stroke induces endogenous repair processes that include proliferation and differentiation of neural stem cells and extensive rewiring of the remaining neural connections, yet about 50% of stroke survivors live with severe long-term disability. There is an unmet need for drug therapies to improve recovery by promoting brain plasticity in the subacute to chronic phase after ischaemic stroke. We previously showed that complement-derived peptide C3a regulates neural progenitor cell migration and differentiation in vitro and that C3a receptor signalling stimulates neurogenesis in unchallenged adult mice. To determine the role of C3a-C3a receptor signalling in ischaemia-induced neural plasticity, we subjected C3a receptor-deficient mice, GFAP-C3a transgenic mice expressing biologically active C3a in the central nervous system, and their respective wild-type controls to photothrombotic stroke. We found that C3a overexpression increased, whereas C3a receptor deficiency decreased post-stroke expression of GAP43 (P < 0.01), a marker of axonal sprouting and plasticity, in the peri-infarct cortex. To verify the translational potential of these findings, we used a pharmacological approach. Daily intranasal treatment of wild-type mice with C3a beginning 7 days after stroke induction robustly increased synaptic density (P < 0.01) and expression of GAP43 in peri-infarct cortex (P < 0.05). Importantly, the C3a treatment led to faster and more complete recovery of forepaw motor function (P < 0.05). We conclude that C3a-C3a receptor signalling stimulates post-ischaemic neural plasticity and intranasal treatment with C3a receptor agonists is an attractive approach to improve functional recovery after ischaemic brain injury.
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Abstract
The complement system is an important part of the innate and adaptive immune systems. Originally characterized as a single serum component contributing to the killing of bacteria, we now know that there are close to sixty complement proteins, multiple activation pathways and a wide range of effector functions mediated by complement. The system plays a critical role in host defense against bacteria, viruses, fungi and other pathogens. However, inappropriate complement activation contributes to the pathophysiology of autoimmune diseases and many inflammatory syndromes. Over the last several decades, therapeutic approaches to inhibit complement activation at various steps in the pathways have met with initial success, particularly at the level of the terminal pathway. This success, combined with insight from animal model studies, has lead to an unprecedented effort by biotech and pharmaceutical companies to begin developing complement inhibitors. As a result, complement has been brought for the first time to the attention of pharmacologists, toxicologists, project managers and others in the drug development industry, as well as those in the investment world. The purpose of this primer is to provide a broad overview of complement immunobiology to help those new to complement understand the rationale behind the current therapeutic directions and the investment potential of these new therapeutics.
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Ramos TN, Arynchyna AA, Blackburn TE, Barnum SR, Johnston JM. Soluble membrane attack complex is diagnostic for intraventricular shunt infection in children. JCI Insight 2016; 1:e87919. [PMID: 27699221 DOI: 10.1172/jci.insight.87919] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Children treated with cerebrospinal fluid (CSF) shunts to manage hydrocephalus frequently develop shunt failure and/or infections, conditions that present with overlapping symptoms. The potential life-threatening nature of shunt infections requires rapid diagnosis; however, traditional microbiology is time consuming, expensive, and potentially unreliable. We set out to identify a biomarker that would identify shunt infection. METHODS CSF was assayed for the soluble membrane attack complex (sMAC) by ELISA in patients with suspected shunt failure or infection. CSF was obtained at the time of initial surgical intervention. Statistical analysis was performed to assess the diagnostic potential of sMAC in pyogenic-infected versus noninfected patients. RESULTS Children with pyogenic shunt infection had significantly increased sMAC levels compared with noninfected patients (3,211 ± 1,111 ng/ml vs. 26 ± 3.8 ng/ml, P = 0.0001). In infected patients undergoing serial CSF draws, sMAC levels were prognostic for both positive and negative clinical outcomes. Children with delayed, broth-only growth of commensal organisms (P. acnes, S. epidermidis, etc.) had the lowest sMAC levels (7.96 ± 1.7 ng/ml), suggesting contamination rather than shunt infection. CONCLUSION Elevated CSF sMAC levels are both sensitive and specific for diagnosing pyogenic shunt infection and may serve as a useful prognostic biomarker during recovery from infection. FUNDING This work was supported in part by the Impact Fund of Children's of Alabama.
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Johnston JM, Ramos TN, Arynchyna AA, Blackburn TE, Amburgy J, Rocque BG, Blount JP, Rozzelle CJ, Oakes J, Barnum SR. 190 Complement Membrane Attack Complex (MAC) Level in CSF Provides Rapid Identification of Shunt Infection and Failure. Neurosurgery 2015. [DOI: 10.1227/01.neu.0000467154.21290.7f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Gong B, Levine S, Barnum SR, Pasinetti GM. Role of complement systems in IVIG mediated attenuation of cognitive deterioration in Alzheimer's disease. Curr Alzheimer Res 2015; 11:637-44. [PMID: 25115545 DOI: 10.2174/1567205011666140812113707] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 06/25/2014] [Accepted: 07/13/2014] [Indexed: 11/22/2022]
Abstract
Human intravenous immunoglobulin (IVIG) has been indicated as a potential therapy for autoimmune neurological disorders, as well as in many neurodegenerative diseases, with various underlying therapeutic mechanisms such as regulation of T-cell trafficking, cytokines, Fc receptor blocking, and interruption of complement activation cascade. In Alzheimer's disease (AD), IVIG presents naturally occurring antibodies against amyloid-beta (Aβ) aggregation, thus IVIG immunotherapy may increase the clearance of Aβ and protect brain function. Recently, we and others reported that besides Aβ clearance, IVIG specifically regulates the levels of complement-derived anaphylatoxins, such as C5a and C3, which play an important role in the regulation of AMPA and NMDA receptor expression in the brain and further upregulate the AMPA-PKA-CREB signaling pathway and synaptic function in AD mouse models. Since down-regulation of complement components has been linked with deficits of cognitive function in age-related dementia following the decline of innate immunity during aging, the IVIG immunotherapy could be an attractive novel AD therapeutic through its local regulation of C3, C5a component levels in brain.
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Barnum SR. C4a: An Anaphylatoxin in Name Only. J Innate Immun 2015; 7:333-9. [PMID: 25659340 DOI: 10.1159/000371423] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 12/08/2014] [Indexed: 12/31/2022] Open
Abstract
Activation of complement leads to generation of the 3 anaphylatoxins C3a, C4a, and C5a. Although all 3 peptides are structurally similar, only C3a and C5a share a similar functional profile that includes the classic inflammatory activities and, more recently, developmental homing and regenerative properties among others. In contrast, the functional profile of C4a is questionable in most cases owing to contamination of C4a preparations with physiologically relevant levels of C3a and/or C5a. Combined with the absence of an identified C4a receptor and the inability of C4a to signal through the C3a and C5a receptors, it is clear that C4a should not be included in the family of complement anaphylatoxins.
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Buckingham SC, Ramos TN, Barnum SR. Complement C5-deficient mice are protected from seizures in experimental cerebral malaria. Epilepsia 2014; 55:e139-42. [PMID: 25385326 DOI: 10.1111/epi.12858] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2014] [Indexed: 12/01/2022]
Abstract
Studies have demonstrated that the membrane attack complex (MAC) of complement can evoke seizures when injected directly into rodent brain. In the course of studies that examine the role of complement in the development of experimental cerebral malaria (ECM), we observed fewer seizures in mice deficient in C5, a component required for MAC formation. To determine if the MAC contributed to the tonic-clonic seizures characteristic of ECM, we performed long-term video-electroencephalography (EEG) on C5(-/-) mice with Plasmodium berghei ANKA-induced cerebral malaria and observed significantly reduced spike and seizure frequency compared to wild-type mice. Our data suggest a role for the MAC in malaria-induced seizures and that inhibition of the terminal complement pathway may reduce seizures and seizure-related neurocognitive deficits.
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Szalai AJ, Barnum SR, Ramos TN. Deletion of C-reactive protein ameliorates experimental cerebral malaria? Trans R Soc Trop Med Hyg 2014; 108:591-3. [PMID: 25002461 DOI: 10.1093/trstmh/tru098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND C-reactive protein (CRP) level correlates with parasitemia and severity of malaria, but whether this reflects causality remains unknown. METHODS Using CRP-transgenic and CRP-deficient mice we compared the onset and severity of experimental cerebral malaria (ECM) induced by Plasmodium berghei ANKA (PbA). RESULTS CRP-deficient mice were most resistant to ECM. CONCLUSIONS CRP might contribute to the development of cerebral malaria, rather than protect against it.
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Ramos TN, Bullard DC, Barnum SR. ICAM-1: isoforms and phenotypes. THE JOURNAL OF IMMUNOLOGY 2014; 192:4469-74. [PMID: 24795464 DOI: 10.4049/jimmunol.1400135] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
ICAM-1 plays an important role in leukocyte trafficking, immunological synapse formation, and numerous cellular immune responses. Although considered a single glycoprotein, there are multiple membrane-bound and soluble ICAM-1 isoforms that arise from alternative splicing and proteolytic cleavage during inflammatory responses. The function and expression of these isoforms on various cell types are poorly understood. In the generation of ICAM-1-deficient mice, two isoform-deficient ICAM-1 mutants were inadvertently produced as a result of alternative splicing. These mice, along with true ICAM-1-deficient mice and newly generated ICAM-1-transgenic mice, have provided the opportunity to begin examining the role of ICAM-1 isoforms (singly or in combination) in various disease settings. In this review, we highlight the sharply contrasting disease phenotypes using ICAM-1 isoform mutant mice. These studies demonstrate that ICAM-1 immunobiology is highly complex but that individual isoforms, aside from the full-length molecule, make significant contributions to disease development and pathogenesis.
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Hu X, Patel RP, Weinberg JA, Marques MB, Ramos TN, Barnum SR. Membrane attack complex generation increases as a function of time in stored blood. Transfus Med 2014; 24:114-6. [PMID: 24588971 DOI: 10.1111/tme.12109] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 11/13/2013] [Accepted: 02/02/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To determine if the complement system, a potent mediator of inflammation, contributes to haemolysis during red blood cell (RBC) storage. BACKGROUND RBCs in storage undergo structural and biochemical changes that may result in adverse patient outcomes post-transfusion. Complement activation on leukodepletion and during storage may contribute to the RBC storage lesion. METHODS/MATERIALS We performed a cross-sectional analysis of aliquots of leukoreduced RBC units, stored for 1-6 weeks, for the levels of C3a, C5a, Bb, iC3b, C4d and C5b-9 [membrane attack complex (MAC)] by enzyme-linked immunosorbent assay (ELISA). RESULTS We observed that only MAC levels significantly increased in RBC units as a function of storage time. We also observed that the level of C5b-9 bound to RBCs increased as a function of storage time. CONCLUSION MAC levels increased over time, suggesting that MAC is the primary complement-mediated contributor to changes in stored RBCs. Inhibition of the terminal complement pathway may stabilise RBC functionality and extend shelf life.
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Bullard DC, Hu X, Crawford D, McDonald K, Ramos TN, Barnum SR. Expression of a single ICAM-1 isoform on T cells is sufficient for development of experimental autoimmune encephalomyelitis. Eur J Immunol 2014; 44:1194-9. [PMID: 24435747 DOI: 10.1002/eji.201344023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 12/02/2013] [Accepted: 01/13/2014] [Indexed: 01/30/2023]
Abstract
Intercellular adhesion molecule-1 (ICAM-1) plays an important role in leukocyte trafficking, induction of cellular immune responses, and immunological synapse formation. As a member of the immunoglobulin superfamily of adhesion proteins, ICAM-1 is composed of repeating Ig-like domains, a transmembrane domain, and short cytoplasmic tail that participates in intracellular signaling events. At least seven ICAM-1 protein isoforms are generated by alternative splicing, however little is known regarding their immunobiology. We have previously shown using different lines of ICAM-1 mutant mice (Icam1(tm1Jcgr) and Icam1(tm1Bay) ) that expression of alternatively spliced ICAM-1 isoforms can significantly influence the disease course during the development of EAE. In this study, we show using a newly developed transgenic mouse (CD2-Icam1(D4del) /Icam1(null) ) that T-cell-specific expression of a single ICAM-1 isoform composed of Ig domains 1, 2, 3, and 5 can mediate the initiation and progression of EAE. Our results indicate that the ICAM-1 isoform lacking Ig domain 4 can drive pathogenesis in demyelinating disease and may be a novel therapeutic target for treating multiple sclerosis.
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Stahel PF, Barnum SR. The role of the complement system in CNS inflammatory diseases. Expert Rev Clin Immunol 2014; 2:445-56. [DOI: 10.1586/1744666x.2.3.445] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Hu X, Barnum SR, Patel RP, Marques MB, Weinberg JA. The level of complement activation fragments is higher in red blood cell units than segments. Transfus Apher Sci 2013; 49:692-3. [PMID: 24189461 DOI: 10.1016/j.transci.2013.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 10/09/2013] [Indexed: 10/26/2022]
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Read RW, Vogt SD, Barnum SR. The complement anaphylatoxin receptors are not required for the development of experimental autoimmune uveitis. J Neuroimmunol 2013; 264:127-9. [PMID: 24035596 DOI: 10.1016/j.jneuroim.2013.08.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/19/2013] [Accepted: 08/21/2013] [Indexed: 02/06/2023]
Abstract
To determine if complement anaphylatoxin-mediated inflammation contributes to the development and progression of experimental autoimmune uveitis (EAU), we induced disease in wild type and complement anaphylatoxin receptor-deficient mice (C3a receptor(-/-), C5a receptor(-/-) and C3aR(-/-)/C5aR(-/-)) and evaluated the eyes three weeks post-induction. No differences in disease severity or in disease incidence were seen between wild type controls and anaphylatoxin receptor-deficient mice. Our data indicate that C3a and C5a-mediated functions are not critical to the development of EAU.
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Hu X, Wetsel RA, Ramos TN, Mueller-Ortiz SL, Schoeb TR, Barnum SR. Carboxypeptidase N-deficient mice present with polymorphic disease phenotypes on induction of experimental autoimmune encephalomyelitis. Immunobiology 2013; 219:104-8. [PMID: 24028840 DOI: 10.1016/j.imbio.2013.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/08/2013] [Accepted: 08/16/2013] [Indexed: 10/26/2022]
Abstract
Carboxypeptidase N (CPN) is a member of the carboxypeptidase family of enzymes that cleave carboxy-terminal lysine and arginine residues from a large number of biologically active peptides and proteins. These enzymes are best known for their roles in modulating the activity of kinins, complement anaphylatoxins and coagulation proteins. Although CPN makes important contributions to acute inflammatory events, little is known about its role in autoimmune disease. In this study we used CPN(-/-) mice in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. Unexpectedly, we observed several EAE disease phenotypes in CPN(-/-) mice compared to wild type mice. The majority of CPN(-/-) mice died within five to seven days after disease induction, before displaying clinical signs of disease. The remaining mice presented with either mild EAE or did not develop EAE. In addition, CPN(-/-) mice injected with complete or incomplete Freund's adjuvant died within the same time frame and in similar numbers as those induced for EAE. Overall, the course of EAE in CPN(-/-) mice was significantly delayed and attenuated compared to wild type mice. Spinal cord histopathology in CPN(-/-) mice revealed meningeal, but not parenchymal leukocyte infiltration, and minimal demyelination. Our results indicate that CPN plays an important role in EAE development and progression and suggests that multiple CPN ligands contribute to the disease phenotypes we observed.
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Hu X, Holers VM, Thurman JM, Schoeb TR, Ramos TN, Barnum SR. Therapeutic inhibition of the alternative complement pathway attenuates chronic EAE. Mol Immunol 2013; 54:302-8. [PMID: 23337717 PMCID: PMC3602149 DOI: 10.1016/j.molimm.2012.12.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 12/14/2012] [Indexed: 12/13/2022]
Abstract
Previous studies from our laboratory using complement-mutant mice demonstrated that the alternative pathway is the dominant activation pathway responsible for complement-mediated pathology in demyelinating disease. Using a well-characterized inhibitory monoclonal antibody (mAb 1379) directed against mouse factor B, we assessed the therapeutic value of inhibiting the alternative complement pathway in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. Administration of anti-factor B antibody to mice prior to the onset of clinical signs of active EAE had no affect on the onset or acute phase of disease, but significantly attenuated the chronic phase of disease resulting in reduced cellular infiltration, inflammation and demyelination in antibody-treated mice. Attenuation of the chronic phase of disease was long lasting even though antibody administration was terminated shortly after disease onset. Chronic disease was also attenuated in transferred EAE when anti-factor B antibody was administered before or after disease onset. Similar levels of disease attenuation were observed in transferred EAE using MOG-specific encephalitogenic T cells. These studies demonstrate the therapeutic potential for inhibition of factor B in the chronic phase of demyelinating disease, where treatment options are limited.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Complement Factor B/classification
- Complement Pathway, Alternative/drug effects
- Complement Pathway, Alternative/immunology
- Complement System Proteins/immunology
- Demyelinating Diseases/immunology
- Disease Models, Animal
- Encephalomyelitis, Autoimmune, Experimental/drug therapy
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Inflammation/immunology
- Mice
- Mice, Inbred C57BL
- T-Lymphocytes/drug effects
- T-Lymphocytes/immunology
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Järlestedt K, Rousset CI, Ståhlberg A, Sourkova H, Atkins AL, Thornton C, Barnum SR, Wetsel RA, Dragunow M, Pekny M, Mallard C, Hagberg H, Pekna M. Receptor for complement peptide C3a: a therapeutic target for neonatal hypoxic‐ischemic brain injury. FASEB J 2013; 27:3797-804. [DOI: 10.1096/fj.13-230011] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Ramos TN, Bullard DC, Darley MM, McDonald K, Crawford DF, Barnum SR. Experimental cerebral malaria develops independently of endothelial expression of intercellular adhesion molecule-1 (icam-1). J Biol Chem 2013; 288:10962-6. [PMID: 23493396 DOI: 10.1074/jbc.c113.457028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cerebral malaria (CM) is a severe clinical complication of Plasmodium falciparum malaria infection and is characterized by a high fatality rate and neurological damage. Sequestration of parasite-infected red blood cells in brain microvasculature utilizes host- and parasite-derived adhesion molecules and is an important factor in the development of CM. ICAM-1, an alternatively spliced adhesion molecule, is believed to be critical on endothelial cells for infected red blood cell sequestration in CM. Using ICAM-1 mutant mice, we found that the full-length ICAM-1 isoform is not required for development of murine experimental CM (ECM) and that ECM phenotype varies with the combination of ICAM-1 isoforms expressed. Furthermore, we observed development of ECM in transgenic mice expressing ICAM-1 only on leukocytes, indicating that endothelial cell expression of this adhesion molecule is not required for disease pathogenesis. We propose that ICAM-1-dependent cellular aggregation, independent of ICAM-1 expression on the cerebral microvasculature, contributes to ECM.
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