carboxypeptidase-b and Disease-Models--Animal

Anopheles gambiae is the major African vector of Plasmodium falciparum, the most deadly species of human malaria parasite and the most prevalent in Africa. Several strategies are being developed to limit the global impact of malaria via reducing transmission rates, among which are transmission-blocking vaccines (TBVs), which induce in the vertebrate host the production of antibodies that inhibit parasite development in the mosquito midgut. So far, the most promising components of a TBV are parasite-derived antigens, although targeting critical mosquito components might also successfully block development of the parasite in its vector. We previously identified A. gambiae genes whose expression was modified in P. falciparum-infected mosquitoes, including one midgut carboxypeptidase gene, cpbAg1. Here we show that P. falciparum up-regulates the expression of cpbAg1 and of a second midgut carboxypeptidase gene, cpbAg2, and that this up-regulation correlates with an increased carboxypeptidase B (CPB) activity at a time when parasites establish infection in the mosquito midgut. The addition of antibodies directed against CPBAg1 to a P. falciparum-containing blood meal inhibited CPB activity and blocked parasite development in the mosquito midgut. Furthermore, the development of the rodent parasite Plasmodium berghei was significantly reduced in mosquitoes fed on infected mice that had been immunized with recombinant CPBAg1. Lastly, mosquitoes fed on anti-CPBAg1 antibodies exhibited reduced reproductive capacity, a secondary effect of a CPB-based TBV that could likely contribute to reducing Plasmodium transmission. These results indicate that A. gambiae CPBs could constitute targets for a TBV that is based upon mosquito molecules.

Topics: Animals; Anopheles; Antibodies; Carboxypeptidase B; Disease Models, Animal; Female; Gastrointestinal Tract; Humans; Malaria; Malaria Vaccines; Malaria, Falciparum; Mice; Plasmodium berghei; Plasmodium falciparum; Reproduction; Up-Regulation

We describe the enzymes that constitute the major bradykinin (BK)-processing pathways in the perfusates of mesenteric arterial bed (MAB) and coronary vessels isolated from Wistar normotensive rats (WNR) and spontaneously hypertensive rats. The contribution of particular proteases to BK degradation was revealed by the combined analysis of fragments generated during incubation of BK with representative perfusate samples and the effect of selective inhibitors on the respective reactions. Marked differences were seen among the perfusates studied; MAB secretes, per minute of perfusion, kininase activity capable of hydrolyzing approximately 300 pmol of BK/min, which is approximately 250-fold larger amount on a per unit time basis than that of its coronary counterpart. BK degradation in the coronary perfusate seems to be mediated by ANG I-converting enzyme, neutral endopeptidase 24.11-like enzyme, and a dl-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid-sensitive basic carboxypeptidase; coronary perfusate of WNR contains an additional BK-degrading enzyme whose specificity resembles that of neurolysin or thimet oligopeptidase. Diversely, a des-Arg(9)-BK-forming enzyme, responsible for nearly all of the kininase activity of MAB perfusates of WNR and spontaneously hypertensive rats, could be purified by a procedure that involved affinity chromatography over potato carboxypeptidase inhibitor-Sepharose column and shown to be structurally identical to rat pancreatic carboxypeptidase B (CPB). Comparable levels of CPB mRNA expression were observed in pancreas, liver, mesentery, and kidney, but very low levels were detected in lung, heart, aorta, and carotid artery. In conclusion, distinct BK-processing pathways operate in the perfusates of rat MAB and coronary bed, with a substantial participation of a des-Arg(9)-BK-forming enzyme identical to pancreatic CPB.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Bradykinin; Carboxypeptidase B; Coronary Circulation; Disease Models, Animal; Gene Expression Regulation, Enzymologic; Hydrolysis; Hypertension; Male; Metalloendopeptidases; Neprilysin; Pancreas; Peptidyl-Dipeptidase A; Perfusion; Protease Inhibitors; Rats; Rats, Inbred SHR; Rats, Wistar; Splanchnic Circulation; Substrate Specificity; Tissue Distribution

A porcine pancreatic transplantation model was used to investigate possible protease activation in the pancreatic graft during preservation. After perfusion with Perfadex and cold ischemia for 24 h, but prior to reperfusion, activated carboxypeptidase B was demonstrated in tissue samples from the graft parenchyma with a Western blot technique, indicating that graft pancreatitis may already be initiated during the preservation phase. A higher degree of carboxypeptidase B activation was observed in grafts perfused at a pressure of 130 cm H20 than after perfusion at 70 cm H20. During reperfusion, the fraction of activated carboxypeptidase B gradually declined but was still detectable after 2 h. One group of pigs received aprotinin intravenously during reperfusion, but the protease inhibitor did not influence the degree of carboxypeptidase B activation in the biopsy specimen. Immunoblotting against cationic trypsinogen/trypsin was also performed. When activated trypsin was detectable, it never presented more than a few percent of the total amount of uncomplexed immunoreactive trypsinogen/trypsin.

Topics: Animals; Aprotinin; Blotting, Western; Carboxypeptidase B; Carboxypeptidases; Disease Models, Animal; Enzyme Activation; Organ Preservation; Pancreas Transplantation; Pancreatitis; Perfusion; Reperfusion; Serine Proteinase Inhibitors; Swine; Trypsinogen