CD43 is required for optimal growth inhibition of Mycobacterium tuberculosis in macrophages and in mice.

Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
The Journal of Immunology (Impact Factor: 5.36). 09/2005; 175(3):1805-12. DOI: 10.4049/jimmunol.175.3.1805
Source: PubMed

ABSTRACT We explored the role of macrophage (Mphi) CD43, a transmembrane glycoprotein, in the pathogenesis of Mycobacterium tuberculosis. Using gene-deleted mice (CD43-/-), we assessed the association of the bacterium with distinct populations of Mphi and found that CD43-/- Mphi bound less M. tuberculosis than CD43+/+ Mphi. Increased infective doses did not abrogate this difference. However, reduced association due to the absence of CD43 could be overcome by serum components. Mphi from heterozygote mice, which express 50% of wild-type CD43, bound more bacteria than CD43-/- but less than CD43+/+, proving that the gene dose of CD43 correlates with binding of M. tuberculosis. Furthermore, the reduced ability of CD43-/- Mphi to bind bacteria was restricted to mycobacterial species. We also found that the survival and replication of M. tuberculosis within Mphi was enhanced significantly in the absence of CD43, making this the first demonstration that the mechanism of mycobacterial entry influences its subsequent growth. Most importantly, we show here that the absence of CD43 in mice aerogenically infected with M. tuberculosis results in an increased bacterial load during both the acute and chronic stages of infection and more rapid development of granulomas, with greater lung involvement and distinctive cellularity.

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Available from: April Kaur Randhawa, Jul 08, 2015
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    • "This procedure has previously been shown by our lab to be an effective means of dispersing mycobacterial bacilli without causing detectable cell lysis (Stokes et al., 2004). Previous work by Randhawa et al. (2005) showed that CD43 -/-MF have a reduced capacity to bind M. tuberculosis, but increasing the cfu inoculum overcame this limitation. As preliminary work showed that an moi of 60:1 for CD43 +/+ cells and 100:1 for CD43 -/-cells resulted in a similar level of bacterial binding in binding medium alone, these two moi were used for infections of the BMMF. "
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    ABSTRACT: CD43 is a large sialylated glycoprotein found on the surface of haematopoietic cells and has been previously shown to be necessary for efficient macrophage binding and immunological responsiveness to Mycobacterium tuberculosis. Using capsular material from M. tuberculosis and recombinant CD43-Fc, we have employed affinity chromatography to show that Cpn60.2 (Hsp65, GroEL), and to a lesser extent DnaK (Hsp70), bind to CD43. Competitive inhibition using recombinant protein and polyclonal F(ab')(2) antibody-mediated epitope masking studies were used to evaluate M. tuberculosis binding to CD43(+/+) versus CD43(-/-) macrophages. Results showed that Cpn60.2, but not DnaK, acts as a CD43-dependent mycobacterial adhesin for macrophage binding. Assessment of the specific binding between Cpn60.2 and CD43 showed it to be saturable, with a comparatively weak affinity in the low micromolar range. We have also shown that the ability of Cpn60.2 to competitively inhibit M. tuberculosis binding to macrophages is shared by the Escherichia coli homologue, GroEL, but not by the mouse and human Hsp60 homologues. These findings add to a growing field of research that implicates molecular chaperones as having extracellular functions, including bacterial adherence to host cells. Thus, CD43 may act as a Pattern Recognition Receptor (PRR) for bacterial homologues of the 60 kDa molecular chaperone.
    Cellular Microbiology 11/2010; 12(11):1634-47. DOI:10.1111/j.1462-5822.2010.01496.x · 4.82 Impact Factor
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    • "The growth of M. tuberculosis within Mf monolayers was evaluated by infecting BMMf and determining bacterial cfu counts over a 7 day period, as previously described (Stokes and Doxsee, 1999; Randhawa et al., 2005). Briefly, 2.5 ¥ 10 5 BMMf were cultured on 13 mm acid-washed sterile glass coverslips in 24-well plates for 7 days, at which point media were replaced with 0.5 ml of supplemented RPMI Ϯ 100 U ml -1 recombinant IFN-g, and left overnight. "
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