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The νSaα Specific Lipoprotein Like Cluster (lpl) of S. aureus USA300 Contributes to Immune Stimulation and Invasion in Human Cells.

Nguyen MT, Kraft B, Yu W, Demircioglu DD, Demicrioglu DD, Hertlein T, Burian M, Schmaler M, Boller K, Bekeredjian-Ding I, Ohlsen K, Schittek B, Götz F - PLoS Pathog. (2015)

Bottom Line: The results showed that the mutant was deficient in the stimulation of pro-inflammatory cytokines in human monocytes, macrophages and keratinocytes.Additionally, in a murine kidney abscess model the bacterial burden in the kidneys was higher in wild type than in mutant mice.In this infection model the lpl cluster, thus, contributes to virulence.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbial Genetics, University of Tübingen, Tübingen, Germany.

ABSTRACT
All Staphylococcus aureus genomes contain a genomic island, which is termed νSaα and characterized by two clusters of tandem repeat sequences, i.e. the exotoxin (set) and 'lipoprotein-like' genes (lpl). Based on their structural similarities the νSaα islands have been classified as type I to IV. The genomes of highly pathogenic and particularly epidemic S. aureus strains (USA300, N315, Mu50, NCTC8325, Newman, COL, JH1 or JH9) belonging to the clonal complexes CC5 and CC8 bear a type I νSaα island. Since the contribution of the lpl gene cluster encoded in the νSaα island to virulence is unclear to date, we deleted the entire lpl gene cluster in S. aureus USA300. The results showed that the mutant was deficient in the stimulation of pro-inflammatory cytokines in human monocytes, macrophages and keratinocytes. Purified lipoprotein Lpl1 was further shown to elicit a TLR2-dependent response. Furthermore, heterologous expression of the USA300 lpl cluster in other S. aureus strains enhanced their immune stimulatory activity. Most importantly, the lpl cluster contributed to invasion of S. aureus into human keratinocytes and mouse skin and the non-invasive S. carnosus expressing the lpl gene cluster became invasive. Additionally, in a murine kidney abscess model the bacterial burden in the kidneys was higher in wild type than in mutant mice. In this infection model the lpl cluster, thus, contributes to virulence. The present report is one of the first studies addressing the role of the νSaα encoded lpl gene cluster in staphylococcal virulence. The finding that the lpl gene cluster contributes to internalization into non-professional antigen presenting cells such as keratinocytes highlights the lpl as a new cell surface component that triggers host cell invasion by S. aureus. Increased invasion in murine skin and an increased bacterial burden in a murine kidney abscess model suggest that the lpl gene cluster serves as an important virulence factor.

No MeSH data available.


Related in: MedlinePlus

Induction of TNF-α, IL-6 by Mono Mac 6 cells infected with various staphylococcal strains.Staphylococcal strains were cultured in TSB+0.8% xylose for 16 h and used to infect 106 Mono Mac 6 cells with a MOI of 30:1. TNF-α and IL-6 were determined after 4 h and 24 h of stimulation. Production of TNF-α (A) and IL-6 (B) by Mono Mac 6 cells infected with S. aureus HG003, HG003 (pTX30::lpl), S. carnosus TM300 (Sc), and Sc (pTX30::lpl). Production of TNF-α (C) and IL-6 (D) by Mono Mac 6 cells infected with S. aureus SA113, SA113Δlgt and SA113Δlgt (pTX30::lpl). The experiments in duplicate were conducted at least 3 times. Error bars indicate standard error. Statistical significances were calculated by using Student's t-tests or analysis of variance (ANOVA): not significant P>0.05, * P<0.05, ** P <0.01.
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ppat.1004984.g004: Induction of TNF-α, IL-6 by Mono Mac 6 cells infected with various staphylococcal strains.Staphylococcal strains were cultured in TSB+0.8% xylose for 16 h and used to infect 106 Mono Mac 6 cells with a MOI of 30:1. TNF-α and IL-6 were determined after 4 h and 24 h of stimulation. Production of TNF-α (A) and IL-6 (B) by Mono Mac 6 cells infected with S. aureus HG003, HG003 (pTX30::lpl), S. carnosus TM300 (Sc), and Sc (pTX30::lpl). Production of TNF-α (C) and IL-6 (D) by Mono Mac 6 cells infected with S. aureus SA113, SA113Δlgt and SA113Δlgt (pTX30::lpl). The experiments in duplicate were conducted at least 3 times. Error bars indicate standard error. Statistical significances were calculated by using Student's t-tests or analysis of variance (ANOVA): not significant P>0.05, * P<0.05, ** P <0.01.

Mentions: We next investigated whether the lpl-cluster exerts a similar immune stimulatory effect in other staphylococcal strains. To this end we cloned pTX30::lpl into S. aureus HG003, which is a rsbU- and tcaR-repaired derivate of NCTC8325 [16] and into S. carnosus TM300, a non-pathogenic foodborne staphylococcal species [11,17]. The results showed that in HG003, as in USA300, xylose-induced expression of the lpl-cluster led to an approximately four-fold induction of TNF-α and IL-6 production (Fig 4A and 4B). In S. carnosus (pTX30::lpl) TNF-α production was only slightly increased and for IL-6 production no difference was observed (Fig 4A and 4B). However, one of the most remarkable differences between the pathogenic S. aureus strains and the non-pathogenic S. carnosus strain was the generally much higher activation of Mono Mac 6 by S. carnosus. While USA300 and HG003 triggered TNF-α production in a range of 500 pg/ml, S. carnosus TM300-derived TNF-α production was increased to > 8000 pg/ml, which is 16 times higher than that of the S. aureus strains. A similar difference was observed with IL-6 (Fig 4A and 4B). Thus, S. carnosus has a much higher TLR2-dependent immune stimulatory activity in Mono Mac 6 than USA300.


The νSaα Specific Lipoprotein Like Cluster (lpl) of S. aureus USA300 Contributes to Immune Stimulation and Invasion in Human Cells.

Nguyen MT, Kraft B, Yu W, Demircioglu DD, Demicrioglu DD, Hertlein T, Burian M, Schmaler M, Boller K, Bekeredjian-Ding I, Ohlsen K, Schittek B, Götz F - PLoS Pathog. (2015)

Induction of TNF-α, IL-6 by Mono Mac 6 cells infected with various staphylococcal strains.Staphylococcal strains were cultured in TSB+0.8% xylose for 16 h and used to infect 106 Mono Mac 6 cells with a MOI of 30:1. TNF-α and IL-6 were determined after 4 h and 24 h of stimulation. Production of TNF-α (A) and IL-6 (B) by Mono Mac 6 cells infected with S. aureus HG003, HG003 (pTX30::lpl), S. carnosus TM300 (Sc), and Sc (pTX30::lpl). Production of TNF-α (C) and IL-6 (D) by Mono Mac 6 cells infected with S. aureus SA113, SA113Δlgt and SA113Δlgt (pTX30::lpl). The experiments in duplicate were conducted at least 3 times. Error bars indicate standard error. Statistical significances were calculated by using Student's t-tests or analysis of variance (ANOVA): not significant P>0.05, * P<0.05, ** P <0.01.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4470592&req=5

ppat.1004984.g004: Induction of TNF-α, IL-6 by Mono Mac 6 cells infected with various staphylococcal strains.Staphylococcal strains were cultured in TSB+0.8% xylose for 16 h and used to infect 106 Mono Mac 6 cells with a MOI of 30:1. TNF-α and IL-6 were determined after 4 h and 24 h of stimulation. Production of TNF-α (A) and IL-6 (B) by Mono Mac 6 cells infected with S. aureus HG003, HG003 (pTX30::lpl), S. carnosus TM300 (Sc), and Sc (pTX30::lpl). Production of TNF-α (C) and IL-6 (D) by Mono Mac 6 cells infected with S. aureus SA113, SA113Δlgt and SA113Δlgt (pTX30::lpl). The experiments in duplicate were conducted at least 3 times. Error bars indicate standard error. Statistical significances were calculated by using Student's t-tests or analysis of variance (ANOVA): not significant P>0.05, * P<0.05, ** P <0.01.
Mentions: We next investigated whether the lpl-cluster exerts a similar immune stimulatory effect in other staphylococcal strains. To this end we cloned pTX30::lpl into S. aureus HG003, which is a rsbU- and tcaR-repaired derivate of NCTC8325 [16] and into S. carnosus TM300, a non-pathogenic foodborne staphylococcal species [11,17]. The results showed that in HG003, as in USA300, xylose-induced expression of the lpl-cluster led to an approximately four-fold induction of TNF-α and IL-6 production (Fig 4A and 4B). In S. carnosus (pTX30::lpl) TNF-α production was only slightly increased and for IL-6 production no difference was observed (Fig 4A and 4B). However, one of the most remarkable differences between the pathogenic S. aureus strains and the non-pathogenic S. carnosus strain was the generally much higher activation of Mono Mac 6 by S. carnosus. While USA300 and HG003 triggered TNF-α production in a range of 500 pg/ml, S. carnosus TM300-derived TNF-α production was increased to > 8000 pg/ml, which is 16 times higher than that of the S. aureus strains. A similar difference was observed with IL-6 (Fig 4A and 4B). Thus, S. carnosus has a much higher TLR2-dependent immune stimulatory activity in Mono Mac 6 than USA300.

Bottom Line: The results showed that the mutant was deficient in the stimulation of pro-inflammatory cytokines in human monocytes, macrophages and keratinocytes.Additionally, in a murine kidney abscess model the bacterial burden in the kidneys was higher in wild type than in mutant mice.In this infection model the lpl cluster, thus, contributes to virulence.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbial Genetics, University of Tübingen, Tübingen, Germany.

ABSTRACT
All Staphylococcus aureus genomes contain a genomic island, which is termed νSaα and characterized by two clusters of tandem repeat sequences, i.e. the exotoxin (set) and 'lipoprotein-like' genes (lpl). Based on their structural similarities the νSaα islands have been classified as type I to IV. The genomes of highly pathogenic and particularly epidemic S. aureus strains (USA300, N315, Mu50, NCTC8325, Newman, COL, JH1 or JH9) belonging to the clonal complexes CC5 and CC8 bear a type I νSaα island. Since the contribution of the lpl gene cluster encoded in the νSaα island to virulence is unclear to date, we deleted the entire lpl gene cluster in S. aureus USA300. The results showed that the mutant was deficient in the stimulation of pro-inflammatory cytokines in human monocytes, macrophages and keratinocytes. Purified lipoprotein Lpl1 was further shown to elicit a TLR2-dependent response. Furthermore, heterologous expression of the USA300 lpl cluster in other S. aureus strains enhanced their immune stimulatory activity. Most importantly, the lpl cluster contributed to invasion of S. aureus into human keratinocytes and mouse skin and the non-invasive S. carnosus expressing the lpl gene cluster became invasive. Additionally, in a murine kidney abscess model the bacterial burden in the kidneys was higher in wild type than in mutant mice. In this infection model the lpl cluster, thus, contributes to virulence. The present report is one of the first studies addressing the role of the νSaα encoded lpl gene cluster in staphylococcal virulence. The finding that the lpl gene cluster contributes to internalization into non-professional antigen presenting cells such as keratinocytes highlights the lpl as a new cell surface component that triggers host cell invasion by S. aureus. Increased invasion in murine skin and an increased bacterial burden in a murine kidney abscess model suggest that the lpl gene cluster serves as an important virulence factor.

No MeSH data available.


Related in: MedlinePlus