We have discovered that alpha1-antitrypsin (alpha1-AT), a major plasma serine proteinase inhibitor, is a potent inhibitor of a group of bacterial hemolytic toxins (hemolysins) by a mechanism that appears to be distinct from its antiprotease function. We propose that alpha1-AT may protect the lung and other tissues from injury by inhibiting toxin- mediated cellular injury during infections, in addition to functioning as an inhibitor of leukocyte elastase. Although alpha1-AT has been extensively characterized by biochemical, molecular, and clinical studies as the major plasma inhibitor of leukocyte elastase, its ability to inhibit non-protease bacterial hemolysins has been completely unexplored. The long term goal of our research is to understand the role of alpha1-AT in host defense against acute lung injury from bacterial infections. The goal of this proposal is to explore the biological significance and biochemical mechanisms of this newly discovered """"""""antihemolysin"""""""" activity of alpha1-AT. Within the scope of this proposal we will focus on the antihemolysin activity of alpha1-AT against one particular toxin, the S. pneumoniae toxin pneumolysin. Specifically, we propose: 1. To establish that alpha1-AT is a biologically significant inhibitor of pneumolysin. a. Is alpha1-AT a major plasma inhibitor of pneumolysin in normal subjects? b. Do patients with various degrees of alpha1-AT deficiency have proportionately reduced plasma antihemolysin activity? c. Is alpha1-AT a major inhibitor of pneumolysin in bronchoalveolar fluid? d. Do other mammalian alpha1-ATs that lack significant antielastase activity have antihemolysin activity? e. Are experimentally alpha1-AT-depleted rats more susceptible to pneumolysin toxicity? 2. To investigate the biochemical mechanisms of the inhibition of pneumolysin by alpha1-AT. a. Does alpha1-AT prevent binding of pneumolysin to cell membranes? b. What is the stoichiometry of pneumolysin binding to alpha1-AT? c. Does the inhibition of pneumolysin by alpha1-AT involve a thiol interaction? d. Is glycosylation required for alpha1-AT antihemolysin activity? Future investigations will extend these observations to the other thiol- activated toxins, study the role that bacterial toxins play in the pathogenesis of emphysema in normal and alpha1-AT deficient patients, and explore the possibility that alpha1-AT augmentation can meliorate pulmonary tissue destruction from bacterial pneumonitis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29AI034051-02
Application #
2069136
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Project Start
1993-04-01
Project End
1998-03-31
Budget Start
1994-04-01
Budget End
1995-03-31
Support Year
2
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Alexander, J E; Berry, A M; Paton, J C et al. (1998) Amino acid changes affecting the activity of pneumolysin alter the behaviour of pneumococci in pneumonia. Microb Pathog 24:167-74
Rubins, J B; Puri, A K; Loch, J et al. (1998) Magnitude, duration, quality, and function of pneumococcal vaccine responses in elderly adults. J Infect Dis 178:431-40
Rubins, J B; Greatens, T; Kratzke, R A et al. (1998) Lovastatin induces apoptosis in malignant mesothelioma cells. Am J Respir Crit Care Med 157:1616-22
Greatens, T M; Niehans, G A; Rubins, J B et al. (1998) Do molecular markers predict survival in non-small-cell lung cancer? Am J Respir Crit Care Med 157:1093-7
Rubins, J B; Pomeroy, C (1997) Role of gamma interferon in the pathogenesis of bacteremic pneumococcal pneumonia. Infect Immun 65:2975-7
Rubins, J B; Charboneau, D; Prigge, W et al. (1996) Ethanol ingestion reduces antipneumococcal activity of rat pulmonary surfactant. J Infect Dis 174:507-12
Rubins, J B; Charboneau, D; Fasching, C et al. (1996) Distinct roles for pneumolysin's cytotoxic and complement activities in the pathogenesis of pneumococcal pneumonia. Am J Respir Crit Care Med 153:1339-46
Rubins, J B; Charboneau, D; Paton, J C et al. (1995) Dual function of pneumolysin in the early pathogenesis of murine pneumococcal pneumonia. J Clin Invest 95:142-50
Amdahl, B M; Rubins, J B; Daley, C L et al. (1995) Impaired natural immunity to pneumolysin during human immunodeficiency virus infection in the United States and Africa. Am J Respir Crit Care Med 152:2000-4
Rubins, J B; Mitchell, T J; Andrew, P W et al. (1994) Pneumolysin activates phospholipase A in pulmonary artery endothelial cells. Infect Immun 62:3829-36

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