It has been revealed in this laboratory that severe combined immunodeficient (SCID) mice, in spite of their inability to generate a specific immune response to infection with attenuated and virulent M. tuberculosis (Mtb), can nevertheless exert an appreciable restrictive influence on the growth of Mtb in their lungs and other organs. This growth restrictive mechanism can be abolished by treating Mtb-infected SCID mice with hydrocortisone, or with monoclonal antibodies (mAbs) directed against TNFalpha, IFNgamma, or neutrophils. The goal of the proposed research is to gain a general understanding of the cellular basis of this non-immune growth restrictive mechanism in the lungs of SCID mice. It is hypothesized that Mtb growth restriction is expressed by macrophages, the antimycobacterial function of which is upregulated as part of a non-immune cellular response to infection. This response will be analyzed histologically to determine whether SCID mice infected by aerosol Mtb is confined to the cytoplasm of lung macrophages while growth restriction is being expressed and after it is abolished by treating mice with the above mentioned reagents. In the latter case, increased bacillary load per macrophage and dissociation of granulomas is expected. The possibility that expression of Mtb growth restriction depends on an influx of monocytes, NK cells and neutrophils from blood will be determined. It will also be determined whether Mtb growth restriction is associated with TNFalpha and IFNgamma production in the lung. A spot ELISA assay will be used to enumerate and identify the cells that produce these cytokines. The need for IFNgamma and TNF to upregulate the Mtb growth restrictive mechanisms of macrophages, and the ability of hydrocortisone to abolish the mechanism will be studied in vitro. It will be determined whether Mtb growth restriction in the lung serves to retard the hematogenous dissemination of infection to other organs.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL051960-01
Application #
3370520
Study Section
Special Emphasis Panel (ZHL1-CSR-N (S3))
Project Start
1993-09-30
Project End
1997-08-31
Budget Start
1993-09-30
Budget End
1994-08-31
Support Year
1
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Trudeau Institute, Inc.
Department
Type
DUNS #
City
Saranac Lake
State
NY
Country
United States
Zip Code
12983
North, R J (1998) Mice incapable of making IL-4 or IL-10 display normal resistance to infection with Mycobacterium tuberculosis. Clin Exp Immunol 113:55-8
Medina, E; North, R J (1998) Resistance ranking of some common inbred mouse strains to Mycobacterium tuberculosis and relationship to major histocompatibility complex haplotype and Nramp1 genotype. Immunology 93:270-4
MacMicking, J D; North, R J; LaCourse, R et al. (1997) Identification of nitric oxide synthase as a protective locus against tuberculosis. Proc Natl Acad Sci U S A 94:5243-8
North, R J; Medina, E (1996) Significance of the antimicrobial resistance gene, Nramp1, in resistance to virulent Mycobacterium tuberculosis infection. Res Immunol 147:493-9
Dunn, P L; North, R J (1996) Persistent infection with virulent but not avirulent Mycobacterium tuberculosis in the lungs of mice causes progressive pathology. J Med Microbiol 45:103-9
Medina, E; North, R J (1996) Evidence inconsistent with a role for the Bcg gene (Nramp1) in resistance of mice to infection with virulent Mycobacterium tuberculosis. J Exp Med 183:1045-51
Medina, E; North, R J (1996) Mice that carry the resistance allele of the Bcg gene (Bcgr) develop a superior capacity to stabilize bacille Calmette-Guerin (BCG) infection in their lungs and spleen over a protracted period in the absence of specific immunity. Clin Exp Immunol 104:44-7
Dunn, P L; North, R J (1995) Virulence ranking of some Mycobacterium tuberculosis and Mycobacterium bovis strains according to their ability to multiply in the lungs, induce lung pathology, and cause mortality in mice. Infect Immun 63:3428-37
North, R J (1995) Mycobacterium tuberculosis is strikingly more virulent for mice when given via the respiratory than via the intravenous route. J Infect Dis 172:1550-3