Host-derived oxidized phospholipids and HDL regulate innate immunity in human leprosy - PubMed (original) (raw)

. 2008 Aug;118(8):2917-28.

doi: 10.1172/JCI34189.

Andrew D Watson, Christopher S Miller, Dennis Montoya, Maria-Teresa Ochoa, Peter A Sieling, Miguel A Gutierrez, Mohamad Navab, Srinivasa T Reddy, Joseph L Witztum, Alan M Fogelman, Thomas H Rea, David Eisenberg, Judith Berliner, Robert L Modlin

Affiliations

Host-derived oxidized phospholipids and HDL regulate innate immunity in human leprosy

Daniel Cruz et al. J Clin Invest. 2008 Aug.

Abstract

Intracellular pathogens survive by evading the host immune system and accessing host metabolic pathways to obtain nutrients for their growth. Mycobacterium leprae, the causative agent of leprosy, is thought to be the mycobacterium most dependent on host metabolic pathways, including host-derived lipids. Although fatty acids and phospholipids accumulate in the lesions of individuals with the lepromatous (also known as disseminated) form of human leprosy (L-lep), the origin and significance of these lipids remains unclear. Here we show that in human L-lep lesions, there was preferential expression of host lipid metabolism genes, including a group of phospholipases, and that these genes were virtually absent from the mycobacterial genome. Host-derived oxidized phospholipids were detected in macrophages within L-lep lesions, and 1 specific oxidized phospholipid, 1-palmitoyl-2-(5,6-epoxyisoprostane E2)-sn-glycero-3-phosphorylcholine (PEIPC), accumulated in macrophages infected with live mycobacteria. Mycobacterial infection and host-derived oxidized phospholipids both inhibited innate immune responses, and this inhibition was reversed by the addition of normal HDL, a scavenger of oxidized phospholipids, but not by HDL from patients with L-lep. The accumulation of host-derived oxidized phospholipids in L-lep lesions is strikingly similar to observations in atherosclerosis, which suggests that the link between host lipid metabolism and innate immunity contributes to the pathogenesis of both microbial infection and metabolic disease.

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Figures

Figure 1

Figure 1. Differential expression of host lipid metabolism genes in polar forms of leprosy.

(A) Genes preferentially expressed in L-lep lesions were categorized according to metabolic function. (B) L-lep lesions preferentially expressed a greater number of lipid metabolism genes, but fewer genes involved in protein metabolism, compared with T-lep lesions. (C) Lipid metabolism genes preferentially expressed in L-lep lesions (n = 6 lesions) and T-lep lesions (n = 5 lesions) were subcategorized according to function and listed by ascending P value. All genes had at least 1.5-fold relative expression and P < 0.05.

Figure 2

Figure 2. Comparative domain profiling between leprosy lesions and mycobacterial genomes.

Top: Number of mycobacterial genes containing functional lipase domains similar to those of the human genes upregulated in L-lep lesion transcriptome. The PFAM domain containing the lipase activity is shown in parentheses. Middle: Phospholipase C genes were absent in M. leprae, but induced in the L-lep transcriptome. Bottom: Number of mycobacterial genes containing selected domains involved in phospholipid biosynthesis. Gene names are listed in parentheses for each domain.

Figure 3

Figure 3. Oxidized phospholipids accumulate in L-lep lesions and during mycobacterial infection.

(A) Human leprosy lesions were labeled with the monoclonal antibody EO6. Shown are representative sections from L-lep (n = 5) and T-lep (n = 4) lesions. Original magnification, ×40. (B) TUNEL in leprosy lesions (n = 4 per group). Original magnification, ×20. (C) Immunofluorescence 3-color confocal microscopy of L-lep lesions. Red stain, EO6; green stain, CD68; blue stain, DAPI. Original magnification, ×63. (D) oxLDL, but not M. leprae sonicate, reacted with EO6, as determined by ELISA. Data (mean ± SEM) are representative of 4 independent experiments. (E) Primary human macrophages accumulated PEIPC during BCG infection. Phospholipids were analyzed by ESI-MS, and relative abundance was determined by comparison with levels of native PAPC. Data are mean ± SEM of 3 independent experiments. *P < 0.001 versus media.

Figure 4

Figure 4. Oxidized phospholipids alter DC differentiation and function.

(A) oxPAPC was separated by HPLC, and 1-minute fractions were collected and individually tested for their effects on CD1b and MHC class II expression on differentiating DCs. Chromatograms demonstrating which fractions contained PGPC, POVPC, and PEIPC have been superimposed with biological activity. (B) Representative fractions enriched in PEIPC (fraction 23), POVPC (fraction 20), and PGPC (fraction 19) differentially affected CD1b expression on differentiating DCs. GM, GM-CSF; FSC, forward scatter; SSC, side scatter. Numbers within plots denote percent cells within gate or positive for CD1b. (C) PEIPC altered DC function. After 48 h differentiation in the presence or absence of 500 ng/ml PEIPC, cells were washed, irradiated, pulsed with antigen, and cocultured with T cell lines. CD1b- or MHC class II–restricted T cell activation was assessed by IFN-γ production. Data (mean ± SEM of triplicate wells) are representative of 3 experiments for CD1b-restricted T cells, 3 experiments for MHC class II–restricted T cells with GroES protein, and 2 experiments using GroES peptide. *P < 0.03 versus GM alone.

Figure 5

Figure 5. Oxidized phospholipids alter TLR2/1 activation.

(A) Monocytes activated with 10 μg/ml TLR2/1 ligand (TLR2/1L) 19 kDa in the presence of PEIPC produced less IL-12 p40, but more IL-10, than those activated with TLR2/1 ligand alone, as determined by ELISA performed in triplicate wells. Data (mean ± SEM) are representative of 2 experiments. (B) Effect of PEIPC on TLR2/1-mediated induction of CYP27b1 mRNA. Monocytes were activated by TLR2/1 ligand in 5% FCS in the presence or absence of PEIPC for 24 h, and CYP27b1 mRNA levels were determined by quantitative PCR. Data are mean ± SEM of 4 separate experiments. *P < 0.03 versus media. (C) Effect of PEIPC on TLR2/1-mediated induction of cathelicidin mRNA. Monocytes were activated by TLR2/1 ligand in 10% human serum (vitamin D sufficient) in the presence or absence of oxPAPC for 24 h, and cathelicidin mRNA levels were determined by quantitative PCR. Data are mean ± SEM of 3 separate experiments. **P = 0.02 versus media.

Figure 6

Figure 6. HDL preserves DC differentiation and function during mycobacterial infection.

(A) Effect of HDL on oxPAPC-mediated inhibition of CD1b+ DC differentiation. Data are representative of 2 experiments. Numbers within plots denote percent CD1b+ cells. (B) Effect of HDL on mycobacteria-mediated inhibition of CD1b+ DC differentiation. Monocytes were infected with BCG alone or with 150 μg/ml HDL. Data are representative of more than 6 experiments. (C) Effect of HDL on CD1b-restricted mycobacterial antigen presentation by M. tuberculosis H37Ra–infected DCs. T cell activation was assessed by IFN-γ release. Data (mean ± SEM of triplicate wells) are representative of 3 experiments. *P < 0.001. (D) Effect of HDL from L-lep patients on CD1b+ DC differentiation. Left: Representative cell surface staining comparing normal and L-lep HDL (50 μg/ml) with and without M. tuberculosis H37Ra (M. tb) infection (MOI, 0.1). Numbers within plots denote percent CD1b+ cells. Right: Percent CD1b+ DCs relative to uninfected. Data represent mean ± SEM of 3 experiments using HDL from normal (n = 3) and L-lep (n = 5) donors. **P ≤ 0.02. (E) Functional assessment of HDL from leprosy patients. Monocyte chemotactic activity in normal (NL; n = 5) and leprosy HDL (L-lep and T-lep, n = 12 per group). ***P = 0.001. L-lep versus T-lep HDL was not significant (P = 0.23). (F) Reverse cholesterol transport with normal and leprosy HDL. Cholesterol efflux with normal (n = 8), L-lep (n = 11), and T-lep (n = 11) HDL (25 μg/ml). ***P = 0.001; #P = 0.049. (G) Effect of normal and leprosy HDL on CD1b+ DC differentiation. Normal (n = 7), L-lep (n = 8), and T-lep (n = 11) HDL (50 μg/ml) was added to differentiating monocytes, and CD1b+ DCs were quantified by flow cytometry. ***P = 0.001; ##P = 0.02.

References

    1. Munoz-Elias E.J., McKinney J.D. Mycobacterium tuberculosis isocitrate lyases 1 and 2 are jointly required for in vivo growth and virulence. Nat. Med. 2005;11:638–644. doi: 10.1038/nm1252. -DOI -PMC -PubMed
    1. Jain M., et al. Lipidomics reveals control of Mycobacterium tuberculosis virulence lipids via metabolic coupling. Proc. Natl. Acad. Sci. U. S. A. 2007;104:5133–5138. doi: 10.1073/pnas.0610634104. -DOI -PMC -PubMed
    1. Reed M.B., et al. A glycolipid of hypervirulent tuberculosis strains that inhibits the innate immune response. Nature. 2004;431:84–87. doi: 10.1038/nature02837. -DOI -PubMed
    1. Cole S.T., et al. Massive gene decay in the leprosy bacillus. Nature. 2001;409:1007–1011. doi: 10.1038/35059006. -DOI -PubMed
    1. Ridley D.S. Histological classification and the immunological spectrum of leprosy. Bull. World Health Organ. 1974;51:451–465. -PMC -PubMed

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