Capsular Arabinomannans from Mycobacterium avium with Morphotype-specific Structural Differences but Identical Biological Activity

Abstract

The capsules of two colony morphotypes of Mycobacterium avium strain 2151 were investigated, i.e. the virulent smoothtransparent (SmT1) and the nonvirulent smooth-opaque (SmO) types. From both morphotypes we separated a nonacylated arabinomannan (AM) from an acylated polysaccharide fraction by affinity chromatography, of which the AMs were structurally characterized. The AMs from the virulent morphotype, in contrast to that from the nonvirulent form, possessed a larger mannan chain and a shorter arabinan chain. Incubation of murine bone marrow-derived macrophages and human dendritic cells showed that the acylated polysaccharide fractions were potent inducers of tumor necrosis factor-␣, interleukin-12, and interleukin-10 compared with nonacylated AMs, which led to only a marginal cytokine release. Further in vitro experiments showed that both the acylated polysaccharide fractions and the nonacylated AMs were able to induce in vitro anti-tumor cytotoxicity of human peripheral blood mononuclear cells. Thus, morphotype-specific structural differences in the capsular AMs of M. avium do not correlate with biological activity; however, their acylation is a prerequisite for effective stimulation of murine macrophages and human dendritic cells.

Association of Human Antibodies to Arabinomannan With Enhanced Mycobacterial Opsonophagocytosis and Intracellular Growth Reduction

“…Thus, the subjects' Abs could have bound to capsular AM and/or the cell wall–associated AM portion of LAM, which is supported by the observation that IgG responses to capsular AM and cell wall LAM correlated strongly and significantly. Of note, when isolated from the same strain, correlations between reactivities to AM and LAM were even stronger than correlations between AM isolated from different strains, supporting that the surface expression of AM is strain dependent [ 19 , 49 , 50 ]. We further showed that postvaccination but not prevaccination sera were reactive with BCG and with M. tuberculosis grown in both the presence and absence of detergent, confirming that Abs elicited through BCG vaccination can opsonize both strains, regardless of culture conditions.…”

Diversity in Mycobacterium tuberculosis mannosylated cell wall determinants impacts adaptation to the host

“…In general, arabinomannans appear to be immunosupressive components that can affect macrophage-dependent antigen-induced TH1 cytokine production by human and murine lymphocytes 67,68,69. Interestingly, a recent study using purified arabinomannans from virulent and non-virulent M. avium strains showed that the degree of acylation of arabinomannan (additional acylation independent of the MGI-anchor) is a prerequisite for the effective stimulation of antigen presenting cells 70.…”

Animal shed Bacillus licheniformis spores possess allergy-protective as well as inflammatory properties

“…Human PBMCs were isolated from citrate-buffered peripheral blood of different healthy donors, independent for each experiment, by gradient centrifugation using Ficoll (PAA Laboratories GmbH, Pasching, Austria), 18 and stimulation with the respective form of B licheniformis 467 followed. When necessary, cells were separated by counterflow elutriation centrifugation to obtain monocytes and lymphocytes.…”