A structural comparison of the total polar lipids from the human archaea Methanobrevibacter smithii and Methanosphaera stadtmanae and its relevance to the adjuvant activities of their liposomes11Publication number 42395 of the National Research Council of Canada.

Sprott, G. Dennis; Brisson, Jean‐Robert; Dicaire, Chantal J.; Pelletier, A.; Deschatelets, Lise; Krishnan, Lakshmi; Patel, G. B.

doi:10.1016/s1388-1981(99)00130-4

Cited by 47 publications

(42 citation statements)

References 24 publications

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“…These may, again, facilitate specific interactions with cells. Interestingly, M. smithii lipids (from which archaeosomes were prepared) exhibit an abundance of archaetidylserine and caldarchaetidylserine (44) that are analogues of phosphatidylserine present in eubacteria that is recognized by CD36 on macrophages (45).…”

Section: Discussionmentioning

confidence: 99%

The Potent Adjuvant Activity of Archaeosomes Correlates to the Recruitment and Activation of Macrophages and Dendritic Cells In Vivo

Krishnan

Sad

Patel

et al. 2001

The Journal of Immunology

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The unique glycerolipids of Archaea can be formulated into vesicles (archaeosomes) with potent adjuvant activity. We studied the effect of archaeosomes on APCs to elucidate the mechanism(s) of adjuvant action. Exposure of J774A.1 macrophages to archaeosomes in vitro resulted in up-regulation of B7.1, B7.2, and MHC class II molecules to an extent comparable to that achieved with LPS. Similarly, incubation of bone marrow-derived DCs with archaeosomes resulted in enhanced expression of MHC class II and B7.2 molecules. In contrast, conventional liposomes made from ester phospholipids failed to modulate the expression of these activation markers. APCs treated with archaeosomes exhibited increased TNF production and functional ability to stimulate allogenic T cell proliferation. More interestingly, archaeosomes enhanced APC recruitment and activation in vivo. Intraperitoneal injection of archaeosomes into mice led to recruitment of Mac1α+, F4/80+ and CD11c+ cells. The expression of MHC class II on the surface of peritoneal cells was also enhanced. Furthermore, peritoneal cells from archaeosome-injected mice strongly enhanced allo-T cell proliferation and cytokine production. The ability of archaeosome-treated APCs to stimulate T cells was restricted to Mac1αhigh, B220− cells in the peritoneum. These Mac1αhigh cells in the presence of GM-CSF gave rise to both F4/80+ (macrophage) and CD11c+ (dendritic) populations. Overall, the activation of APCs correlated to the ability of archaeosomes to induce strong humoral, T helper, and CTL responses to entrapped Ag. Thus, the recruitment and activation of professional APCs by archaeosomes constitutes an efficient self-adjuvanting process for induction of Ag-specific responses to encapsulated Ags.

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Section: Discussionmentioning

confidence: 99%

The Potent Adjuvant Activity of Archaeosomes Correlates to the Recruitment and Activation of Macrophages and Dendritic Cells In Vivo

Krishnan

Sad

Patel

et al. 2001

The Journal of Immunology

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“…In this study, four different archaeosome preparations with divergent head group and lipid core compositions (Table I) all showed CTL activity. We have earlier related the structural properties of the TPL from the human archaea, M. smithii and M. stadtmanae, to their contrasting humoral adjuvant activity (15). High amounts of archaetidyl inositol and ␤-Glcp-(1, 6)-␤-Glcp-(1,1)-archaeol (present in M. stadtmanae) correlated with low adjuvant activity, whereas major lipids having phosphoserine head groups were found in M. smithii TPL.…”

Section: Discussionmentioning

confidence: 99%

Archaeosomes Induce Long-Term CD8+ Cytotoxic T Cell Response to Entrapped Soluble Protein by the Exogenous Cytosolic Pathway, in the Absence of CD4+ T Cell Help

Krishnan

Sad

Patel

et al. 2000

The Journal of Immunology

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The unique ether glycerolipids of Archaea can be formulated into vesicles (archaeosomes) with strong adjuvant activity for MHC class II presentation. Herein, we assess the ability of archaeosomes to facilitate MHC class I presentation of entrapped protein Ag. Immunization of mice with OVA entrapped in archaeosomes resulted in a potent Ag-specific CD8+ T cell response, as measured by IFN-γ production and cytolytic activity toward the immunodominant CTL epitope OVA257–264. In contrast, administration of OVA with aluminum hydroxide or entrapped in conventional ester-phospholipid liposomes failed to evoke significant CTL response. The archaeosome-mediated CD8+ T cell response was primarily perforin dependent because CTL activity was undetectable in perforin-deficient mice. Interestingly, a long-term CTL response was generated with a low Ag dose even in CD4+ T cell deficient mice, indicating that the archaeosomes could mediate a potent T helper cell-independent CD8+ T cell response. Macrophages incubated in vitro with OVA archaeosomes strongly stimulated cytokine production by OVA-specific CD8+ T cells, indicating that archaeosomes efficiently delivered entrapped protein for MHC class I presentation. This processing of Ag was Brefeldin A sensitive, suggesting that the peptides were transported through the endoplasmic reticulum and presented by the cytosolic MHC class I pathway. Finally, archaeosomes induced a potent memory CTL response to OVA even 154 days after immunization. This correlated to strong Ag-specific up-regulation of CD44 on splenic CD8+ T cells. Thus, delivery of proteins in self-adjuvanting archaeosomes represents a novel strategy for targeting exogenous Ags to the MHC class I pathway for induction of CTL response.

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“…Exceptions include the methanogens Methanobacteriaceae methanosphaera (Koga et al, 1998) and Methanobrevibacter smithii (Sprott et al, 1999), the halophile genus Natronobacterium (Upasani et al, 1994), and some thermoacidophiles, albeit in very low quantities (Sprott et al, 1997).…”

Section: Hydroxyarchaeolmentioning

confidence: 99%

Archaeal lipids in Mediterranean cold seeps: molecular proxies for anaerobic methane oxidation

Pancost

Hopmans

Damsté

2001

Geochimica et Cosmochimica Acta

266

175

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Abstract-We investigated the distributions and ␦ 13 C values of biomarkers for Archaea associated with anaerobic methane oxidation in disparate settings throughout two Eastern Mediterranean mud dome fields. All major classes of archaeal lipids are present in the studied sediments, including isoprenoid glycerol diethers, isoprenoid glycerol dialkyl glycerol tetraethers, and irregular isoprenoid hydrocarbons. Of the compounds present, many, including a novel glycerol tetraether and sn-3-hydroxyarchaeol, have not been previously reported for settings in which methane oxidation is presumed to occur. Archaeal lipids are depleted in 13 C, indicating that the Archaea from which they derive are either directly or indirectly involved with methane consumption. The most widespread archaeal lipids are archaeol, PMI, and glycerol tetraethers, and these compounds are present at all active sites. However, archaeal lipid abundances and distributions are highly variable; ratios of crocetane, PMI, and hydroxyarchaeol relative to archaeol vary from 0 to 6.5, from 0 to 2, and from 0 to 1, respectively. These results suggest that archaeal communities differ amongst the sites examined. In addition, carbon isotopic variability amongst archaeal biomarkers in a given mud breccia can be as large as 24 ‰, suggesting that even at single sites multiple archaeal species perform or are supported by anaerobic methane oxidation.

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A structural comparison of the total polar lipids from the human archaea Methanobrevibacter smithii and Methanosphaera stadtmanae and its relevance to the adjuvant activities of their liposomes11Publication number 42395 of the National Research Council of Canada.

Cited by 47 publications

References 24 publications

The Potent Adjuvant Activity of Archaeosomes Correlates to the Recruitment and Activation of Macrophages and Dendritic Cells In Vivo

The Potent Adjuvant Activity of Archaeosomes Correlates to the Recruitment and Activation of Macrophages and Dendritic Cells In Vivo

Archaeosomes Induce Long-Term CD8+ Cytotoxic T Cell Response to Entrapped Soluble Protein by the Exogenous Cytosolic Pathway, in the Absence of CD4+ T Cell Help

Archaeal lipids in Mediterranean cold seeps: molecular proxies for anaerobic methane oxidation

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