title: Mycobacterial sulfolipid shows a virulence by inhibiting cord factor induced granuloma formation and TNF-alpha release.
abstract: Virulence mechanism of infection with Mycobacterium tuberculosis is currently focused to be clarified in the context of cell surface lipid molecule. Comparing two mycobacterial glycolipids, we observed toxicity and prominent granulomatogenic activity of trehalose 6,6'-dimycolate (TDM) injection in mice, evident by delayed body weight gain and histological observations, whereas 2,3,6,6'-tetraacyl trehalose 2'-sulfate (SL) was non-toxic and non-granulomatogenic. Likewise, TDM but not SL caused temporarily, but marked increase of lung indices, indicative of massive granuloma formation. Interestingly, co-administration of TDM and SL prevented these symptoms distinctively and SL inhibited TDM-induced release of tumor necrosis factor alpha (TNF-alpha) in a dose-dependent manner. Histological findings and organ index changes also showed marked inhibition of TDM induced granuloma formation by co-administration of SL. Simultaneous injection of SL together with TDM was highly effective for this protection, as neither injection 1h before nor after TDM injection showed highly inhibitory. In parallel studies on a cellular level, TDM elicited strong TNF-alpha release from alveolar but not from peritoneal macrophages in vitro. This effect was blocked when alveolar macrophages were incubated in wells simultaneously coated with TDM and SL, indicating that SL suppresses TDM-induced TNF-alpha release from macrophages. Our results suggest a novel mechanism by which SL could contribute to virulence at early stage of mycobacterial infection or stimulation with the glycolipids by counteracting the immunopotentiating effect of TDM.
authors.affiliation: Japan BCG Central Laboratory, 3-1-5 Matsuyama, Kiyose-shi, Tokyo 204-0022, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Fujita
authors.forename: Takashi
authors.initials: T
authors.lastname: Naka
authors.forename: Manabu
authors.initials: M
authors.lastname: Hirai
authors.forename: Ikuko
authors.initials: I
authors.lastname: Tomiyasu
authors.forename: Ikuya
authors.initials: I
authors.lastname: Yano
mesh_terms: D000818:Animals; D003311:Cord Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000633:toxicity*; D006017:Glycolipids / Q000378:metabolism / Q000633:toxicity*; D006099:Granuloma / Q000139:chemically induced* / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008813:Mice, Inbred ICR; D009169:Mycobacterium tuberculosis / Q000378:metabolism*; D013045:Species Specificity; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism*; D037521:Virulence Factors
chemical_list: D003311:Cord Factors; D006017:Glycolipids; D014409:Tumor Necrosis Factor-alpha; D037521:Virulence Factors; C009355:sulfolipid I