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.
View Article and Find Full Text PDFDysregulated activation of inflammatory signaling by the immature neonatal immune system could lead to the development of many pediatric diseases including necrotizing enterocolitis (NEC). While the mechanism(s) of pathogenesis is unknown, NEC is believed to have multifactorial causes. Microbial dysbiosis and intestinal immaturity have been implicated as potential triggers for this disease.
View Article and Find Full Text PDFObjectives: 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).
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.
View Article and Find Full Text PDFComplement 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.
View Article and Find Full Text PDFIschaemic 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.
View Article and Find Full Text PDFThe 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.
View Article and Find Full Text PDFBackground: 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.
View Article and Find Full Text PDFActivation 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.
View Article and Find Full Text PDFThe extravasation of CD4(+) effector/memory T cells (TEM cells) across the blood-brain barrier (BBB) is a crucial step in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) or multiple sclerosis (MS). Endothelial ICAM-1 and ICAM-2 are essential for CD4(+) TEM cell crawling on the BBB prior to diapedesis. Here, we investigated the influence of cell surface levels of endothelial ICAM-1 in determining the cellular route of CD4(+) TEM -cell diapedesis across cytokine treated primary mouse BBB endothelial cells under physiological flow.
View Article and Find Full Text PDFStudies 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.
View Article and Find Full Text PDFHuman 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.
View Article and Find Full Text PDFTrans R Soc Trop Med Hyg
September 2014
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.
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.
View Article and Find Full Text PDFIntercellular 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.
View Article and Find Full Text PDFBackground: The transfusion of relatively older red blood cells (RBCs) has been associated with both morbidity and mortality in trauma patients in observational studies. Although the mechanisms responsible for this phenomenon remain unclear, alterations in the microcirculation as a result of the transfusion of relatively older blood may be a causative factor. To assess this hypothesis, we evaluated microvascular perfusion in trauma patients during RBC transfusion.
View Article and Find Full Text PDFTo 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.
View Article and Find Full Text PDFCarboxypeptidase 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.
View Article and Find Full Text PDFBackground: Complement component C5-derived C5a locally generated in the brain has been shown to protect against glutamate-induced neuronal apoptosis and beta-amyloid (Aβ) toxicity, but the mechanism is not clear. In this study, we tested the hypothesis that C5a influences upstream signal transduction pathways associated with cAMP-response element-binding protein (CREB) activation, in which alterations of CREB levels are associated with cognitive deterioration in AD.
Methods: CREB signaling pathway, synaptic plasticity and cognitive function were studied in C5a receptor knockout mice (C5aR(-/-)), C5a over expressing mice (C5a/GFAP) and in Tg2576 mice, an AD mouse model.
Complement is an essential component of inflammation that plays a role in ischemic brain injury. Recent reports demonstrate novel functions of complement in normal and diseased CNS, such as regulation of neurogenesis and synapse elimination. Here, we examined the role of complement-derived peptide C3a in unilateral hypoxia-ischemia (HI), a model of neonatal HI encephalopathy.
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