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The formyl peptide receptor like-1 and scavenger receptor MARCO are involved in glial cell activation in bacterial meningitis.

Braun BJ, Slowik A, Leib SL, Lucius R, Varoga D, Wruck CJ, Jansen S, Podschun R, Pufe T, Brandenburg LO - J Neuroinflammation (2011)

Bottom Line: Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO.Thus the receptors contribute an important part to the host defence against infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy and Cell Biology, RWTH Aachen University, Germany.

ABSTRACT

Background: Recent studies have suggested that the scavenger receptor MARCO (macrophage receptor with collagenous structure) mediates activation of the immune response in bacterial infection of the central nervous system (CNS). The chemotactic G-protein-coupled receptor (GPCR) formyl-peptide-receptor like-1 (FPRL1) plays an essential role in the inflammatory responses of host defence mechanisms and neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the antimicrobial peptide cathelicidin CRAMP/LL-37 is up-regulated in bacterial meningitis, but the mechanisms underlying CRAMP expression are far from clear.

Methods: Using a rat meningitis model, we investigated the influence of MARCO and FPRL1 on rCRAMP (rat cathelin-related antimicrobial peptide) expression after infection with bacterial supernatants of Streptococcus pneumoniae (SP) and Neisseria meningitides (NM). Expression of FPRL1 and MARCO was analyzed by immunofluorescence and real-time RT-PCR in a rat meningitis model. Furthermore, we examined the receptor involvement by real-time RT-PCR, extracellular-signal regulated kinases 1/2 (ERK1/2) phosphorylation and cAMP level measurement in glial cells (astrocytes and microglia) and transfected HEK293 cells using receptor deactivation by antagonists. Receptors were inhibited by small interference RNA and the consequences in NM- and SP-induced Camp (rCRAMP gene) expression and signal transduction were determined.

Results: We show an NM-induced increase of MARCO expression by immunofluorescence and real-time RT-PCR in glial and meningeal cells. Receptor deactivation by antagonists and small interfering RNA (siRNA) verified the importance of FPRL1 and MARCO for NM- and SP-induced Camp and interleukin-1β expression in glial cells. Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.

Conclusions: We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO. Thus the receptors contribute an important part to the host defence against infection.

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Bacterial supernatants of Neisseria meningitidis induced MARCO expression in primary rat astrocytes and meningeal cells. Astrocytes (A and B), microglia (C and D) and meningeal cells (E and F) were incubated with bacterial supernatants of Gram-positive bacteria Streptococcus pneumoniae (SP) or Gram-negative bacteria Neisseria meningitidis (NM) for 0, 6, 12 and 24 h. FPRL1 or MARCO mRNA expression was analyzed using SYBR green real-time RT-PCR and results were compared to the untreated sample. GAPDH (housekeeping gene) was used as an internal control. The data were assessed from three independent experiments in triplicate. An asterisk indicates a significant difference (**, p < 0.001; *, p < 0.05) compared to control as determined by ANOVA followed by the Bonferroni test.
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Figure 1: Bacterial supernatants of Neisseria meningitidis induced MARCO expression in primary rat astrocytes and meningeal cells. Astrocytes (A and B), microglia (C and D) and meningeal cells (E and F) were incubated with bacterial supernatants of Gram-positive bacteria Streptococcus pneumoniae (SP) or Gram-negative bacteria Neisseria meningitidis (NM) for 0, 6, 12 and 24 h. FPRL1 or MARCO mRNA expression was analyzed using SYBR green real-time RT-PCR and results were compared to the untreated sample. GAPDH (housekeeping gene) was used as an internal control. The data were assessed from three independent experiments in triplicate. An asterisk indicates a significant difference (**, p < 0.001; *, p < 0.05) compared to control as determined by ANOVA followed by the Bonferroni test.

Mentions: In a first set of experiments we investigated the expression of both the FPRL1 and MARCO receptor by primary astrocytes, microglia and meningeal cells after stimulation with either NM or SP bacterial supernatants for 0, 6, 12, 24 h by real-time RT-PCR technique. As shown in Figure 1A and 1C, NM or SP does not induce a significant increase of FPRL1 expression in astrocytes as well as microglia. Only in meningeal cells, SP induced a significant increase of FPRL1 expression after 12 h of treatment (4 ± 0.5-fold increase in expression; Figure 1E). In astrocytes, a significant increase of MARCO expression by NM after 12 h of treatment was detected (5 ± 0.8-fold increase in expression; Figure 1B). For SP treatment, we could not detect an increase of MARCO expression. In microglia no significant changes of receptor expressions were observed after NM as well as SP treatment (Figure 1D). In meningeal cells, maximum MARCO expression was reached by NM after 24 h of treatment and by SP after 6 h of treatment (9 ± 0.6- and 6.1 ± 1.3-fold increase in expression, respectively; Figure 1F).


The formyl peptide receptor like-1 and scavenger receptor MARCO are involved in glial cell activation in bacterial meningitis.

Braun BJ, Slowik A, Leib SL, Lucius R, Varoga D, Wruck CJ, Jansen S, Podschun R, Pufe T, Brandenburg LO - J Neuroinflammation (2011)

Bacterial supernatants of Neisseria meningitidis induced MARCO expression in primary rat astrocytes and meningeal cells. Astrocytes (A and B), microglia (C and D) and meningeal cells (E and F) were incubated with bacterial supernatants of Gram-positive bacteria Streptococcus pneumoniae (SP) or Gram-negative bacteria Neisseria meningitidis (NM) for 0, 6, 12 and 24 h. FPRL1 or MARCO mRNA expression was analyzed using SYBR green real-time RT-PCR and results were compared to the untreated sample. GAPDH (housekeeping gene) was used as an internal control. The data were assessed from three independent experiments in triplicate. An asterisk indicates a significant difference (**, p < 0.001; *, p < 0.05) compared to control as determined by ANOVA followed by the Bonferroni test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3040686&req=5

Figure 1: Bacterial supernatants of Neisseria meningitidis induced MARCO expression in primary rat astrocytes and meningeal cells. Astrocytes (A and B), microglia (C and D) and meningeal cells (E and F) were incubated with bacterial supernatants of Gram-positive bacteria Streptococcus pneumoniae (SP) or Gram-negative bacteria Neisseria meningitidis (NM) for 0, 6, 12 and 24 h. FPRL1 or MARCO mRNA expression was analyzed using SYBR green real-time RT-PCR and results were compared to the untreated sample. GAPDH (housekeeping gene) was used as an internal control. The data were assessed from three independent experiments in triplicate. An asterisk indicates a significant difference (**, p < 0.001; *, p < 0.05) compared to control as determined by ANOVA followed by the Bonferroni test.
Mentions: In a first set of experiments we investigated the expression of both the FPRL1 and MARCO receptor by primary astrocytes, microglia and meningeal cells after stimulation with either NM or SP bacterial supernatants for 0, 6, 12, 24 h by real-time RT-PCR technique. As shown in Figure 1A and 1C, NM or SP does not induce a significant increase of FPRL1 expression in astrocytes as well as microglia. Only in meningeal cells, SP induced a significant increase of FPRL1 expression after 12 h of treatment (4 ± 0.5-fold increase in expression; Figure 1E). In astrocytes, a significant increase of MARCO expression by NM after 12 h of treatment was detected (5 ± 0.8-fold increase in expression; Figure 1B). For SP treatment, we could not detect an increase of MARCO expression. In microglia no significant changes of receptor expressions were observed after NM as well as SP treatment (Figure 1D). In meningeal cells, maximum MARCO expression was reached by NM after 24 h of treatment and by SP after 6 h of treatment (9 ± 0.6- and 6.1 ± 1.3-fold increase in expression, respectively; Figure 1F).

Bottom Line: Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO.Thus the receptors contribute an important part to the host defence against infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy and Cell Biology, RWTH Aachen University, Germany.

ABSTRACT

Background: Recent studies have suggested that the scavenger receptor MARCO (macrophage receptor with collagenous structure) mediates activation of the immune response in bacterial infection of the central nervous system (CNS). The chemotactic G-protein-coupled receptor (GPCR) formyl-peptide-receptor like-1 (FPRL1) plays an essential role in the inflammatory responses of host defence mechanisms and neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the antimicrobial peptide cathelicidin CRAMP/LL-37 is up-regulated in bacterial meningitis, but the mechanisms underlying CRAMP expression are far from clear.

Methods: Using a rat meningitis model, we investigated the influence of MARCO and FPRL1 on rCRAMP (rat cathelin-related antimicrobial peptide) expression after infection with bacterial supernatants of Streptococcus pneumoniae (SP) and Neisseria meningitides (NM). Expression of FPRL1 and MARCO was analyzed by immunofluorescence and real-time RT-PCR in a rat meningitis model. Furthermore, we examined the receptor involvement by real-time RT-PCR, extracellular-signal regulated kinases 1/2 (ERK1/2) phosphorylation and cAMP level measurement in glial cells (astrocytes and microglia) and transfected HEK293 cells using receptor deactivation by antagonists. Receptors were inhibited by small interference RNA and the consequences in NM- and SP-induced Camp (rCRAMP gene) expression and signal transduction were determined.

Results: We show an NM-induced increase of MARCO expression by immunofluorescence and real-time RT-PCR in glial and meningeal cells. Receptor deactivation by antagonists and small interfering RNA (siRNA) verified the importance of FPRL1 and MARCO for NM- and SP-induced Camp and interleukin-1β expression in glial cells. Furthermore, we demonstrated a functional interaction between FPRL1 and MARCO in NM-induced signalling by real-time RT-PCR, ERK1/2 phosphorylation and cAMP level measurement and show differences between NM- or SP-induced signal transduction.

Conclusions: We propose that NM and SP induce glial cell activation and rCRAMP expression also via FPRL1 and MARCO. Thus the receptors contribute an important part to the host defence against infection.

Show MeSH
Related in: MedlinePlus