Changes of the cortex proteome and Apolipoprotein E in transgenic mouse models of Alzheimer's Disease.

Transgenic mice carrying human Amyloid Precursor Protein mutations present amyloid plaque deposition in the brain upon aging. In this study, we characterized the changes of cortex proteome and endogenous Apolipoprotein E in these mice. Differential analysis of two-dimensional electrophoresis images revealed spots altered upon aging, transgene addition and plaque deposition. Alpha-synuclein and cytochrome oxidase polypeptide Va were up-regulated in transgenic mice. Upon aging, expression of ATP synthase alpha, alpha enolase, UMP-CMP kinase, and dihydropyrimidinase like-2 protein was modified. These proteins and their modification probably play a role in the amyloid aggregate formation in these mice.

TSG-6 is concentrated in the extracellular matrix of mouse cumulus oocyte complexes through hyaluronan and inter-alpha-inhibitor binding.

During development of ovarian follicles in mammals, cumulus cells and the oocyte form a mucoelastic mass that detaches itself from peripheral granulosa cell layers upon an ovulatory surge. The integrity of this cumulus-oocyte complex (COC) relies on the cohesiveness of a hyaluronan (HA)-enriched extracellular matrix (ECM). We previously identified a serum glycoprotein, inter-alpha-inhibitor (IalphaI), that is critical in organizing and stabilizing this matrix. Following an ovulatory stimulus, IalphaI diffuses into the follicular fluid and becomes integrated in the ECM through its association with HA. TSG-6 (the secreted product of the tumor necrosis factor-stimulated gene 6), another HA binding protein, forms a complex with IalphaI in synovial fluid. The purpose of this study was to investigate whether TSG-6 is involved in the ECM organization of COCs. Immunolocalization of TSG-6 and IalphaI in mouse COCs at different ovulatory stages was analyzed by immunofluorescence and laser confocal microscopy. IalphaI, TSG-6, and HA colocolized in the cumulus ECM. Western blot analyses were consistent with the presence of both TSG-6 and TSG-6/IalphaI complexes in ovulated COCs. These results suggest that TSG-6 has a structural role in COC matrix formation possibly mediating cross-linking of separate HA molecules through its binding to IalphaI.

Evidence that the serum inhibitor of hyaluronidase may be a member of the inter-alpha-inhibitor family.

A study of the uncharacterized serum inhibitors of hyaluronidase, first described half a century ago, was undertaken. Activity was measured against bovine testicular hyaluronidase using a microtiter-based assay and reverse hyaluronan substrate gel zymography. The predominant inhibitory activity was magnesium-dependent and could be eliminated by protease or chondroitinase digestion and by heat treatment. Kinetics of inhibition were similar against hyaluronidases from testis and snake and bee venoms. The inhibitor had no effect on Streptomyces hyaluronidase, indicating that inhibition was not through protection of the hyaluronan substrate. Inhibition levels in serum were increased in mice following carbon tetrachloride or interleukin-1 injection, inducers of the acute-phase response. Reverse zymography identified a predominant band of 120-kDa relative molecular size, with two bands of greater and one of smaller size. The predominant protein was tentatively identified as a member of the inter-alpha-inhibitor family. Inhibition was also observed using either purified inter-alpha-inhibitor or an inter-alpha-inhibitor-related 120-kDa complex. Inter-alpha-inhibitor, found in the hyaluronan-rich cumulus mass surrounding mammalian ova and the coat of fibroblasts and mesothelial cells, may function to stabilize such matrices by protecting against hyaluronidase degradation. Turnover of circulating hyaluronan is extraordinarily rapid, with a half-life of 2-5 min. Prompt increases in levels of serum hyaluronan occur in patients with shock, septicemia, or massive burns, increases that can be attributed, in part, to suppression of degradation by these acute-phase reactants, the inhibitors of hyaluronidase.

Inter-alpha-inhibitor (IalphaI) concentration in pig plasma is independent of acute phase protein response.

Human inter-alpha-inhibitor (IalphaI) has been shown to exert a beneficial therapeutic effect in a porcine model of endotoxin shock. It is therefore useful to have a better understanding of IalphaI metabolism during severe inflammatory syndromes. Experimental bacterial pneumonia was induced in pigs. The acute phase response was highlighted by an increase in pig major acute phase protein (pig-MAP) and haptoglobin concentrations in plasma collected daily over 4 days. In the same samples, the IalphaI levels remained unchanged. Moreover, crossed-immunoelectrophoretic and immunoblot analyses did not show any qualitative modification of IalphaI throughout the experiment. IalphaI has been reported to be a negative acute phase protein in both humans and rats. Here we demonstrated that IalphaI behavior clearly differs in humans and pigs and is definitively species specific.

Effects of inter-alpha-inhibitor in experimental endotoxic shock and disseminated intravascular coagulation.

We investigated the effects of human inter-alpha-inhibitor (I alpha I) on hemodynamics, oxygenation, and coagulation parameters in a porcine model of endotoxic shock. Four groups of six animals were studied: (1) control, (2) I alpha I group receiving 30 mg/kg I alpha I over 30 min, (3) LPS group receiving 5 micrograms.kg/min Escherichia coli endotoxin over 30 min, and (4) LPS + I alpha I group receiving 30 min after endotoxin 30 mg/kg/30 min I alpha I. We measured hemodynamic and oxygenation parameters, usual coagulation markers and plasma levels of thrombin-antithrombin complexes, antithrombin III activity, plasminogen activator tissue type, plasminogen activator inhibitor type 1, von Willebrand factor, tumor necrosis factor-alpha, and I alpha I at baseline and at 30, 60, 90, 120, 180, 240, and 300 min. In the I alpha I group, plasma I alpha I levels reached 447 +/- 23 mg/L just after injection and 287 +/- 39 mg/L at 300 min. I alpha I half-life was 7.3 +/- 1.9 h. In the IPS + I alpha I group, I alpha I plasma levels decreased more rapidly, reaching 260 mg/L at 300 min. Compared with the LPS group, administration of I alpha I normalized the mean arterial pressure and cardiac index, improved the LPS-induced pulmonary hypertension, and resulted in the blunted increase in blood lactate and oxygen extraction ratio. A significant decrease in thrombin-antithrombin complexes and plasminogen activator inhibitor type 1 levels were observed. There was no significant difference in plasma tumor necrosis factor-alpha levels. We concluded that in this hypodynamic model of endotoxin shock, I alpha I administration resulted in a marked improvement in the hemodynamic, oxygenation, and coagulation parameters.

Purification and characterization of pig inter-alpha-inhibitor and its constitutive heavy chains.

With the view of investigating the metabolism of inter-alpha-inhibitor, a plasma serine-proteinase inhibitor, in an animal model of inflammatory syndrome, we isolated inter-alpha-inhibitor from pig plasma. A high yield was obtained (140 mg/liter) with a two-step procedure: anion-exchange chromatography followed by affinity chromatography on heparin-Sepharose. In contrast to bovine inter-alpha-inhibitor was highly similar to human inter-alpha-inhibitor: its heavy chains are homologous to the human H1 and H2 heavy chains, as shown by chromatographic and electrophoretic properties, cross-immunoreactivity and N-terminal sequencing. Pig may therefore represent a good animal model to study inter-alpha-inhibitor metabolism and elucidate its physiological role.

Pig I alpha I appears unmodified in plasma in case of endotoxin-induced disseminated intravascular coagulation.

The unrestricted activity of leukocyte proteinases is thought to contribute to the degradation of plasma proteins and thus amplify the coagulation disorders occurring in septic shock. Inter-alpha-inhibitor (I alpha I) is a plasma protein particularly susceptible to their action. Therefore we investigated its behavior in a porcine model of endotoxin shock which reproduces the coagulation changes observed in human sepsis. We did not detect any qualitative or quantitative modification of porcine I alpha I in plasmas collected from pigs after endotoxin infusion. To explain these data, I alpha I was incubated with polymorphonuclear neutrophils (PMN) stimulated by FMLP in the presence of cytochalasin B. We found that, unlike human PMN, porcine cells were unable to proteolyze I alpha I. Moreover, in the incubation medium of pig PMN, triggered either by FMLP or PMA, no measurable elastase activity was evidenced. Therefore, we urge to better take into account species differences in functional responses of PMN, to explain the experimental results obtained in animal models of septic shock.

Bacterial enzymes used for colon-specific drug delivery are decreased in active Crohn's disease.

Enzymes produced by colonic microflora have been proposed for triggering local delivery of antiinflammatory azo-bond drugs and prodrugs to the colon. This approach could be advantageous in steroid treatment of inflammatory bowel diseases, thus sparing steroids' side effects. We recently demonstrated that the metabolic activity of digestive flora, assessed on the activity of fecal glycosidases, was decreased in patients with active Crohn's disease. In the present study, the azoreductase activity in feces of 14 patients with active Crohn's disease was decreased (11.39 +/- 7.93 mU/g F) as compared with 12 healthy subjects (51.13 +/- 21.39 mU/g F). beta-D-Glucosidase and beta-D-glucuronidase activities in fecal homogenates incubated under anaerobic conditions were also decreased in patients. These data bring into question the therapeutic usefulness for those patients of azo-bond drugs and glycoside prodrugs. They could explain the therapeutic failure of some of those drugs in active ileocolic and colic Crohn's disease.