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Immunobiology Jul 2022
Intrinsic chemical reactivity of activated human complement component C3: A historical glimpse into research during 1979-1980 on the covalent binding properties of C3, C4 and alpha-2 macroglobulin.
Topics: Complement C3; Complement C4; Female; Humans; Pregnancy; Pregnancy-Associated alpha 2-Macroglobulins
PubMed: 35841752
DOI: 10.1016/j.imbio.2022.152209 -
The Journal of Experimental Medicine Aug 1970Activation of plasma kallikrein arginine esterase activity by kaolin resulted in peak activity at 1 min of incubation and a 50% reduction in activity at 5 min in normal...
Activation of plasma kallikrein arginine esterase activity by kaolin resulted in peak activity at 1 min of incubation and a 50% reduction in activity at 5 min in normal plasma, and 30% reduction in the plasma of patients with hereditary angioneurotic edema who lacked the C1 inactivator. The peak esterolytic activity was inhibited by soybean trypsin inhibitor whereas the 5 min activity was resistant to this inhibitor. Acid treatment of normal and hereditary angioneurotic edema plasma destroyed the factor responsible for the fall in esterase activity at 5 min and the factor which rendered the esterase resistant to soybean trypsin inhibitor. Purified alpha(2)-macroglobulin inhibited approximately 50% of the TAMe esterase activity of purified plasma kallikrein without changing its activity toward basic amino acid esters. The interaction between the alpha(2)-macroglobulin and kallikrein resulted in alterations in the gel filtration chromatographic pattern of the TAMe esterase and biologic activity of kallikrein, indicating that kallikrein was bound to the alpha(2)-macroglobulin. The TAMe esterase activity of this complex, isolated by column chromatography, was resistant to C1 inactivator and SBTI. Studies of incubation mixtures of kallikrein, alpha(2)-macroglobulin and C1 inactivator suggested that these inhibitors compete for the enzyme, and that the alpha(2)-macroglobulin partially protects the esterase activity of kallikrein from C1 inactivator. The alpha(2)-macroglobulin isolated from kaolin-activated plasma possessed 240 times the esterolytic activity of the alpha(2)-macroglobulin purified from plasma treated with inhibitors of kallikrein and of its activation. The alpha(2)-macroglobulin blocked the uterine-containing activity and vascular permeability-inducing effects of plasma kallikrein. These studies suggest that the alpha(2)-macroglobulin is a major plasma inhibitor of kallikrein and provide a new example of an interrelationship between the coagulation, fibrinolytic, and kallikrein enzyme systems.
Topics: Alpha-Globulins; Angioedema; Aprotinin; Arginine; Blood Coagulation; Capillary Permeability; Chemical Phenomena; Chemistry; Chromatography; Chromatography, Gel; Complement System Proteins; Culture Techniques; Electrophoresis; Esterases; Factor XI Deficiency; Female; Humans; Hydrochloric Acid; Immunodiffusion; Immunoelectrophoresis; Kallikreins; Kaolin; Kinins; Macroglobulins; Uterus
PubMed: 4101346
DOI: 10.1084/jem.132.2.329 -
Annals of Surgery Mar 2003To analyze the effect of CO2 pneumoperitoneum on the inflammatory response induced by sepsis during laparoscopy.
OBJECTIVE
To analyze the effect of CO2 pneumoperitoneum on the inflammatory response induced by sepsis during laparoscopy.
SUMMARY BACKGROUND DATA
A growing body of evidence challenges the once generally accepted notion that smaller incisions alone account for the observed benefits of the laparoscopic approach. Furthermore, laparoscopic surgery is now being applied to a broad spectrum of patients, including those in whom the inflammatory response is ignited. Delineation of the effects of CO2 pneumoperitoneum on the inflammatory response induced by sepsis is needed.
METHODS
Sepsis was induced in rats by cecal ligation and puncture (CLP) performed either open or laparoscopically using CO2 or helium as insufflation gases. Animals were killed 24 hours postoperatively, at which time whole blood was collected for complete blood cell counts and livers were harvested for analysis of hepatic expression of the rat acute phase genes alpha2-macroglobulin and beta-fibrinogen.
RESULTS
Laparoscopic CLP using CO2 resulted in significantly reduced hepatic expression of the rat acute phase gene alpha2-macroglobulin compared to both laparoscopic CLP using helium and open CLP. Hepatic expression of another rat acute phase gene, beta-fibrinogen, paralleled that of alpha2-macroglobulin and was significantly reduced following laparoscopic CLP using CO2 compared to laparoscopic CLP using helium. Total white blood cell and neutrophil counts following CLP were both significantly higher when CLP was performed laparoscopically using CO2 than when CLP was performed open or laparoscopically using helium.
CONCLUSIONS
Intra-abdominal CO2 present during laparoscopy attenuates the acute phase inflammatory response associated with perioperative sepsis.
Topics: Acute-Phase Proteins; Animals; Blood Cell Count; Carbon Dioxide; Female; Fibrinogen; Gene Expression; Laparoscopy; Liver; Pneumoperitoneum, Artificial; RNA, Messenger; Rats; Rats, Sprague-Dawley; Sepsis; alpha-Macroglobulins
PubMed: 12616117
DOI: 10.1097/01.SLA.0000055271.58945.E2 -
The Journal of Biological Chemistry Dec 1983Human alpha 2-macroglobulin (alpha 2M) undergoes a conformational change after reaction with proteases. In this report, it is shown that although two trypsin molecules...
Human alpha 2-macroglobulin (alpha 2M) undergoes a conformational change after reaction with proteases. In this report, it is shown that although two trypsin molecules may bind simultaneously to each alpha 2M, only one trypsin is necessary to induce alpha 2M conformational change. Ternary complexes of alpha 2M and either two radioiodinated trypsins or two nonradioiodinated trypsins were purified by gel filtration chromatography. The nonradioactive complex did not bind 125I-trypsin, even after incubation for 24 h with the free protease present at a large molar excess. Under comparable conditions, a large molar excess of nonradioactive trypsin did not cause significant dissociation of the complex prepared with radioiodinated protease. Equations are presented that distinguish between two separate models of protease binding and demonstrate that binary alpha 2M-trypsin complex retains no significant trypsin binding activity despite the presence of a vacant protease binding site. Purified alpha 2M-plasmin complex, with 1.10 mol of plasmin/mol of inhibitor, also retained no trypsin binding activity as assessed with radioiodinated protein binding experiments. These studies suggest that reactions of alpha 2M with proteases are accurately described by the "trap hypothesis" (Barrett, A. J., and Starkey, P. M. (1973) Biochem. J. 133, 709-724) independent of protease size or binding stoichiometry.
Topics: Fibrinolysin; Humans; Macromolecular Substances; Mathematics; Protein Conformation; Trypsin; alpha-Macroglobulins
PubMed: 6196365
DOI: No ID Found -
Journal of Biochemistry Feb 1988Green turtle plasma alpha-macroglobulin and ovomacroglobulin underwent conformational changes when they were treated with proteinases or methylamine. Their...
Green turtle plasma alpha-macroglobulin and ovomacroglobulin underwent conformational changes when they were treated with proteinases or methylamine. Their conformational changes were studied by HPLC gel chromatography, circular dichroism, and electron microscopy. The Stokes radii of native green turtle alpha-macroglobulin and ovomacroglobulin were estimated to be 84.3 +/- 0.5 A, and 93.0 +/- 0.5 A, respectively, by means of an HPLC experiment. After reaction with methylamine or proteinases, the Stokes radius of alpha-macroglobulin changed to 83.0 +/- 0.5 A or 85.4 +/- 0.5 A, respectively, and that of ovomacroglobulin to 93.0 +/- 0.5 A or 87.1 +/- 0.5 A. The circular dichroic spectra of native alpha-macroglobulin and ovomacroglobulin exhibited a negative band at around 215 nm, indicating the presence of beta-structure. Reaction of the two macroglobulins with methylamine resulted in a slight decrease in the ellipticity and reaction with proteinases led to a slight increase. The electron micrographic images of native alpha-macroglobulin and ovomacroglobulin can be described as deformed rings for the former and rugby balls for the latter. A common characteristic feature of the two molecules was that the central parts of the molecules were only thinly occupied by subunit. After reaction of macroglobulins with proteinases, the void spaces became partially filled and their overall shape more rectangular. Methylamine treatment caused a structural change only in alpha-macroglobulin but not in ovomacroglobulin. The difference in the susceptibility of the macroglobulins to methylamine was taken as an indication of evolutional divergence of the two homologous proteins within the last 300 million years.
Topics: Animals; Chromatography, High Pressure Liquid; Circular Dichroism; Egg Proteins; Macroglobulins; Microscopy, Electron; Protein Conformation; Turtles; alpha-Macroglobulins
PubMed: 2453504
DOI: 10.1093/oxfordjournals.jbchem.a122251 -
Molecular & Cellular Proteomics : MCP 2021Human α-macroglobulin (A2M) is the most characterized protease inhibitor in the alpha-macroglobulin (αM) superfamily, but the structure of its native conformation has...
Human α-macroglobulin (A2M) is the most characterized protease inhibitor in the alpha-macroglobulin (αM) superfamily, but the structure of its native conformation has not been determined. Here, we combined negative stain electron microscopy (EM), small-angle X-ray scattering (SAXS), and cross-linking-mass spectrometry (XL-MS) to investigate native A2M and its collapsed conformations that are obtained through aminolysis of its thiol ester by methylamine or cleavage of its bait region by trypsin. The combined interpretation of these data resulted in a model of the native A2M tetramer and its conformational changes. Native A2M consists of two crescent-shaped disulfide-bridged subunit dimers, which face toward each other and surround a central hollow space. In native A2M, interactions across the disulfide-bridged dimers are minimal, with a single major interface between the linker (LNK) regions of oppositely positioned subunits. Bait region cleavage induces both intrasubunit domain repositioning and an altered configuration of the disulfide-bridged dimer. These changes collapse the tetramer into a more compact conformation, which encloses an interior protease-trapping cavity. A recombinant A2M with a modified bait region was used to map the bait region's position in native A2M by XL-MS. A second recombinant A2M introduced an intersubunit disulfide into the LNK region, demonstrating the predicted interactions between these regions in native A2M. Altogether, our native A2M model provides a structural foundation for understanding A2M's protease-trapping mechanism, its conformation-dependent receptor interactions, and the dissociation of native A2M into dimers due to inflammatory oxidative stress.
Topics: HEK293 Cells; Humans; Mass Spectrometry; Microscopy, Electron; Mutation; Peptide Hydrolases; Protein Conformation; Recombinant Proteins; Scattering, Small Angle; alpha-Macroglobulins
PubMed: 33964423
DOI: 10.1016/j.mcpro.2021.100090 -
The Journal of Biological Chemistry Jul 1995Alpha 2-Macroglobulin (alpha 2M) is a multifunctional secreted glycoprotein that serves as a ubiquitous proteinase inhibitor and as a binding protein for... (Comparative Study)
Comparative Study
Alpha 2-Macroglobulin (alpha 2M) is a multifunctional secreted glycoprotein that serves as a ubiquitous proteinase inhibitor and as a binding protein for platelet-derived growth factor (PDGF) BB and homologues of PDGF-BB secreted in culture by macrophages. The interaction of alpha 2M with PDGF-A chain molecules has not been addressed. This is a potentially important issue because fibroblasts and smooth muscle cells produce PDGF-AA, whereas macrophages produce mainly PDGF-BB. Recombinant human 125I-PDGF-B chain molecules (AB and BB) bound to plasma-derived, native human, or bovine alpha 2M and trypsin-activated alpha 2M on Superose 6 fast protein liquid chromatography gel filtration and on nondenaturing polyacrylamide gel electrophoresis, whereas 125I-PDGF-AA did not. Similar results were obtained with 125I-PDGF isoforms binding to immobilized bovine alpha 2M and alpha 2M-methylamine. The same differential pattern of unlabeled PDGF isoforms binding to alpha 2M was observed by Western blotting of PDGF. Human lung fibroblasts secreted alpha 2M as measured by Western blotting, and fibroblast-derived alpha 2M possessed the same differential binding pattern for PDGF isoforms as did plasma-derived alpha 2M. The specific binding of PDGF-AB and -BB to these fibroblasts was inhibited by native bovine alpha 2M, although PDGF-AA binding was not affected. Native alpha 2M preferentially blocked fibroblast chemotaxis to the PDGF-B chain dimers. These data suggest that only PDGF-B chain dimers, such as those produced by macrophages or released from platelets, are regulated by alpha 2M and that PDGF-AA produced by fibroblasts and smooth muscle cells is not controlled by this cytokine-binding protein.
Topics: Animals; Becaplermin; Binding, Competitive; Blood Platelets; Blotting, Western; Cattle; Cells, Cultured; Chemotaxis; Fibroblasts; Humans; Macrophages; Muscle, Smooth; Platelet-Derived Growth Factor; Protein Binding; Proto-Oncogene Proteins c-sis; Receptors, Platelet-Derived Growth Factor; alpha-Macroglobulins
PubMed: 7541796
DOI: 10.1074/jbc.270.27.16236 -
Thorax Nov 1997Plasma exudation-derived proteins and peptides contribute significantly to inflammation in the airway mucosa in vivo. In the guinea pig trachea both histamine and the... (Comparative Study)
Comparative Study
BACKGROUND
Plasma exudation-derived proteins and peptides contribute significantly to inflammation in the airway mucosa in vivo. In the guinea pig trachea both histamine and the neurogenic stimulant capsaicin produce acute mucosal tissue distribution and luminal entry of bulk plasma, whereas cholinergic agonists fail to produce this effect. Of these agents, only histamine induces mucosal exudation of plasma in human nasal airways. The exudative effect of the above agents on human bronchi remains unknown.
METHODS
The bronchial exudative responses to inhalation of histamine, methacholine, and capsaicin were examined in two groups of healthy volunteers. Sputum was induced on three occasions in each study group by inhalation of hypertonic saline (4.5%) given as an aerosol for 40 minutes using an ultrasonic nebuliser. The second and third occasions were preceded by histamine and capsaicin challenges in the first study group, and by histamine and methacholine challenges in the second study group. Histamine and methacholine were given in cumulative doses (total doses 3160 micrograms, respectively) or until a 20% reduction in forced expiratory volume in one second (FEV1) was achieved. Cumulative doses of capsaicin were inhaled until coughing prevented the subjects from drawing a full breath. Sputum levels of alpha 2-macroglobulin (729 kDa) were measured as an index of mucosal exudation of bulk plasma.
RESULTS
Histamine increased mean (SE) sputum levels of alpha 2-macroglobulin from 2.72 (1.01) micrograms/ml (95% confidence interval (CI) 0.49 to 4.94) to 18.38 (8.03) micrograms/ml (95% CI 0.49 to 36.27) in the first group, and from 1.66 (0.84) micrograms/ml (95% CI -0.18 to 3.49) to 9.43 (3.63) micrograms/ml (95% CI 1.59 to 17.27) in the second group. In contrast, capsaicin evoked no exudation (sputum levels of alpha 2-macroglobulin 1.21 (0.28) micrograms/ml (95% CI 0.59 to 1.83)) and methacholine produced a minor increase in sputum levels of alpha 2-macroglobulin (2.90 (0.92) micrograms/ml (95% CI 0.90 to 4.89)).
CONCLUSIONS
These results indicate that histamine is a useful agent for studying bronchial exudative responsiveness in man and that exudative effects are only of marginal importance in the cough and bronchoconstriction produced by capsaicin and methacholine.
Topics: Administration, Inhalation; Adult; Aerosols; Bronchial Provocation Tests; Bronchoconstrictor Agents; Capsaicin; Female; Histamine; Humans; Male; Methacholine Chloride; Sputum; Statistics, Nonparametric; alpha-Macroglobulins
PubMed: 9487344
DOI: 10.1136/thx.52.11.964 -
Thrombosis Research Jun 2010Microparticles (MP) are submicron size membrane vesicles released from activated cells that are associated with thrombosis and inflammation. MP present diverse...
BACKGROUND
Microparticles (MP) are submicron size membrane vesicles released from activated cells that are associated with thrombosis and inflammation. MP present diverse biological expressions that may be linked to a unique subset of proteins derived from their origin cells.
METHODS
To identify these proteins, plasma samples were taken from 9 patients with deep venous thrombosis (DVT) documented by duplex ultrasound, 9 with leg pain but negative for DVT by duplex, and 6 healthy controls without a history of thrombosis, for fold variation. MP were extracted from platelet-poor plasma, digested separately with trypsin and tagged using iTRAQ reagents. The digests were subjected to 2-D LC separation followed by MALDI tandem mass spectrometry. Peak lists were generated and searched against all human sequences. For protein identification, a minimum of two peptides at 95% confidence was required. Later, iTRAQ ratios were generated comparing relative protein levels of DVT patients to baseline. The proteomic analysis was performed twice for each blood sample. Proteins were considered elevated or depressed if the iTRAQ ratio (R) deviated by 20% change from normal and a p-value less than 0.05.
RESULTS
Two proteins (Galectin-3 Binding Protein, [Gal3BP], R=1.76 and Alpha-2 macroglobulin [A2M] R=1.57) were differentially expressed on DVT patients. Nine proteins were depleted including fibrinogen beta and gamma chain precursors (R=0.65).
CONCLUSIONS
These proteins influence thrombosis through inflammation, cell shedding, inhibition of fibrinolysis and hemostatic plug formation. Further studies are needed to confirm the mechanistic role of these proteins in the pathogenesis of venous thrombosis in humans.
Topics: Antigens, Neoplasm; Biomarkers, Tumor; Carrier Proteins; Case-Control Studies; Cell-Derived Microparticles; Glycoproteins; Hemostasis; Humans; Inflammation; Proteomics; Venous Thrombosis; alpha-Macroglobulins
PubMed: 20156641
DOI: 10.1016/j.thromres.2010.01.019 -
F1000Research 2019Public health authorities in low- and middle-income countries face dramatic challenges in handling rapidly increasing non-communicable diseases (NCDs), due to the...
Public health research needs for molecular epidemiology and to emphasize homeostasis - could the omnipotent endopeptidase inhibitor α-2-macroglobulin be a meaningful biomarker?
Public health authorities in low- and middle-income countries face dramatic challenges in handling rapidly increasing non-communicable diseases (NCDs), due to the epidemiological- and particularly nutritional transition. Among major reasons for the development of NCDs are smoking and alcohol, but overnutrition and obesity are also major threats to population health. Obesity is related to diabetes and cancer, but also has a genetic background. It is difficult to recommend a healthy nutrition. This is because of conflicting nutritional conceptions, and given the complexity of human metabolism understanding this topic can be difficult for the laymen. Public health measures advocating physical activity and refraining from high intake of energy, sugar and soft drinks need to be enhanced by supporting the 'intrinsic motivation' to preserve a good health. The mission of public health should be to increase awareness about the complexity of human metabolism, and the involvement of genetic and epigenetics in health and diseases. To maintain homeostasis, means to keep an optimal relationship between catabolism and synthesis, seems to be of particular interest. Preconditions for this is, that public health institutions within the administration- and academic sector follow up developments in life science and molecular biology and conduct population-based research making use of molecular epidemiology, especially those related to key metabolic steps and maintenance of 'homeostasis', in balancing catabolism and anabolism. A prospective biomarker for this situation might be α-2-macroglobulin.
Topics: Biomarkers; Endopeptidases; Female; Homeostasis; Humans; Molecular Epidemiology; Pregnancy; Pregnancy-Associated alpha 2-Macroglobulins; Prospective Studies; Public Health
PubMed: 31824660
DOI: 10.12688/f1000research.19781.1