Search results for "complement system"
showing 10 items of 157 documents
On the pathogenesis of atherosclerosis: enzymatic transformation of human low density lipoprotein to an atherogenic moiety.
1995
Combined treatment with trypsin, cholesterol esterase, and neuraminidase transforms LDL, but not HDL or VLDL, to particles with properties akin to those of lipid extracted from atherosclerotic lesions. Single or double enzyme modifications, or treatment with phospholipase C, or simple vortexing are ineffective. Triple enzyme treatment disrupts the ordered and uniform structure of LDL particles, and gives rise to the formation of inhomogeneous lipid droplets 10-200 nm in diameter with a pronounced net negative charge, but lacking significant amounts of oxidized lipid. Enzymatically modified LDL (E-LDL), but not oxidatively modified LDL (ox-LDL), is endowed with potent complement-activating c…
Molecular mechanisms of primary and secondary mucosal immunity using avian infectious bronchitis virus as a model system
2007
Although mucosal immune responses are critical for protection of hosts from clinical illness and even mortality caused by mucosal pathogens, the molecular mechanism of mucosal immunity, which is independent of systemic immunity, remains elusive. To explore the mechanistic basis of mucosal protective immunity, gene transcriptional profiling in mucosal tissues was evaluated after the primary and secondary immunization of animals with an attenuated avian infectious bronchitis virus (IBV), a prototype of Coronavirus and a well-characterized mucosal pathogen. Results showed that a number of innate immune factors including toll-like receptors (TLRs), retinoic-acid-inducible gene-1 (RIG-1), type I…
The efficacy of two immunostimulants against Flavobacterium columnare infection in juvenile rainbow trout (Oncorhynchus mykiss).
2009
Abstract Bacterium Flavobacterium columnare is the causative agent of columnaris disease in many wild and farmed fish species. Immunostimulants are used with success in aquaculture against many pathogens, but the ability to improve innate resistance to columnaris disease has not been studied. Fingerling rainbow trout were treated with two immunostimulants, yeast β-glucan and β-hydroxy-β-methylbutyrate (HMB). Selected innate immune function parameters, the production of reactive oxygen species (ROS) by whole blood and by isolated head kidney leukocytes, plasma lysozyme activity and complement bacteriolytic activity, were determined to assess the immune status of fish. The fish were then bath…
The Complement System: Activation and Control
1985
One of the hallmarks of immunology has been analysis and characterization of the C system in biological fluids. It is composed of 11 proteins of the “classical” pathway:1 C1q, C1r, C1s, C4, C2, C3, C5, C6, C7, C8, and C9. There are three proteins of the “alternative” pathway (IUIS-WHO Nomenclature Committee 1981) B, D, and P. Finally, there are four control proteins: C1 inhibitor (Cl¯ INH) and C4b binding protein (C4b-bp) for the classical pathway, I (C3b inactivator or C3b INA) and H (β1 or C3b INA accelerator) for the alternative pathway, and anaphylatoxin inactivator. Due to the dramatic advances in protein chemistry, these 19 distinct serum proteins have been highly purified and charact…
Biosynthesis of the Collagen-like C1q Molecule and its Receptor Functions for Fc and Polyanionic Molecules on Macrophages
1983
At the beginning of the nineteenth century, knowledge of immunity was limited to a few practical methods based on empirical observations, e.g., the observation by Jenner in 1798 that inoculation with cowpox material induced an immunity to smallpox. The discoveries by Louis Pasteur and Robert Koch that microorganisms caused fermentations and were responsible for a number of infectious diseases, greatly advanced the concepts of susceptibility and immunity in a limited number of diseases. In the late nineteenth century, the complement system was discovered by Fodor(1887), Nuttall(1888), and Buchner (1889a, b) through studying the bactericidal action of blood serum. It was recognized that killi…
Pathogenesis of Atherosclerosis: The Alternative Hypothesis
1998
The concept that oxidation is the major single event underlying the transformation of LDL to a proinflammatory molecule dominates the world literature. An alternative hypothesis on the pathogenesis of atherosclerosis will be presented here. We have found that nonoxidative, enzymatic modification of LDL with ubiquitous enzymes also transforms the molecule to an atherogenic moiety. Enzymatically altered LDL (E-LDL) shares major properties in common with lipoproteins that have been isolated from atherosclerotic lesions. It activates complement and is recognized by a scavenger receptor on human macrophages, thus inducing foam cell formation. Uptake of E-LDL is accompanied by induction of MCP−1 …
The Role of Lectins in Finfish: A Review
2019
The immune system of vertebrates involves both innate and acquired immune responses. The innate immunity is more generalized with robust response whereas the other has a highly specific response to infectious pathogens. Because of the lack of specialized lymphatic organs, innate immunity is an important mode of defense in fishes. The less specific innate immune system acts mainly through complement pathway which depends on pattern-based recognition of “self” and “non-self” targets by host lectins and associated proteins. This ultimately results in the clearance of target cells. Lectins are glycoproteins which possess at least one carbohydrate recognition domain (CRD) that specifically and r…
Formation and function of a complement-activating enzyme generated from factors of guinea pig serum and cobra venom
1971
An enzymatic complex can be formed by factors from guinea pig serum and cobra venom, which is able to activate C3 bypassing C1, C4 and C2. Formation and action of the enzyme are described. The action on C3 results in an activation of the terminal complement components and in membrane destruction provided suitable membrane receptors are available.
The Inflammatory Feed-Forward Loop Triggered by the Complement Component C3 as a Potential Target in Endometriosis
2021
Copyright © 2021 Agostinis, Zorzet, Balduit, Zito, Mangogna, Macor, Romano, Toffoli, Belmonte, Morello, Martorana, Borelli, Ricci, Kishore and Bulla. The complement system is a major component of humoral innate immunity, acting as a first line of defense against microbes via opsonization and lysis of pathogens. However, novel roles of the complement system in inflammatory and immunological processes, including in cancer, are emerging. Endometriosis (EM), a benign disease characterized by ectopic endometrial implants, shows certain unique features of cancer, such as the capacity to invade surrounding tissues, and in severe cases, metastatic properties. A defective immune surveillance against…
C1q–Ha matrix regulates the local synthesis of hyaluronan in malignant pleural mesothelioma by modulating has3 expression
2021
Increased hyaluronic acid (HA) production is often associated with cancer progression. In malignant pleural mesothelioma (MPM), HA is found at elevated levels in pleural effusions and sera of patients, and it has been widely debated whether MPM cells are able to produce HA by themselves or through the release of growth factors stimulating other cells. Another key component of the MPM microenvironment is C1q, which can act as a pro-tumorigenic factor favoring cell adhesion, migration and proliferation. The aim of the current study was to prove that MPM primary cells are able to synthesize HA and to inquire the stimulus given by C1q&ndash