Influence of the glycopeptidic moiety of mycobacterial glycopeptidolipids on their lateral organization in phospholipid monolayers

Altered expression profile of mycobacterial surface glycopeptidolipids following treatment with the antifungal azole inhibitors econazole and clotrimazole

The azole antifungal drugs econazole and clotrimazole are known cytochrome P450 enzyme inhibitors. This study shows that these drugs are potent inhibitors of mycobacterial growth and are more effective against Mycobacterium smegmatis than isoniazid and ethionamide, two established anti-mycobacterial drugs. Several non-tuberculous mycobacteria, including the pathogenic members of the Mycobacterium avium-intracellulare complex (MAC) and the fast-growing saprophytic organism M. smegmatis, produce an array of serovar-specific (ss) and non-serovar-specific (ns) glycopeptidolipids (GPLs). GPL biosynthesis has been investigated for several years but has still not been fully elucidated. The authors demonstrate here that econazole and clotrimazole inhibit GPL biosynthesis in M. smegmatis. In particular, clotrimazole inhibits all four types of nsGPLs found in M. smegmatis, suggesting an early and common target within their biosynthetic pathway. Altogether, the data suggest that an azole-specific target, most likely a cytochrome P450, may be involved in the hydroxylation of the N-acyl chain in GPL biosynthesis. Azole antifungal drugs and potential derivatives could represent an interesting new range of anti-mycobacterial drugs, especially against opportunistic human pathogens including MAC, M. scrofulaceum, M. peregrinum, M. chelonae and M. abscessus.

Role of leukotrienes in killing of Mycobacterium bovis by neutrophils

The neutrophil (PMN) plays an important role in the phagocytosis and killing of microorganisms. Pro-inflammatory leukotrienes (LT) play an important role in various disease states. However LT elaborated by PMN have also been shown to be important in host defense, specifically phagocytosis and killing of microorganisms. Defective LT synthesis by phagocytes correlates with their reduced anti-microbial activity. Therefore, we determined if LT played an important role in the killing of Mycobacteria bovis (M. bovis) by PMN. Endogenous LT play a role in the killing of mycobacteria since the LT synthesis inhibitor MK-886 reversed the killing of M. bovis by PMN. Increased synthesis of LT occurred following incubation of PMN with M. bovis. Treatment with granulocyte-colony stimulating factor, which augments PMN LT synthesis, also boosted anti-microbial activity. Furthermore, exogenous LTB4 augmented dose-dependent killing of M. bovis by PMN. In conclusion, LT play a vital role in promoting mycobactericidal actions of PMN.