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Bacterial lipopolysaccharide rapidly inhibits expression of C-C chemokine receptors in human monocytes.

Sica A, Saccani A, Borsatti A, Power CA, Wells TN, Luini W, Polentarutti N, Sozzani S, Mantovani A - J. Exp. Med. (1997)

Bottom Line: As expected, LPS-induced inhibition of CCR2 mRNA expression was associated with a reduction of both MCP-1 binding and chemotactic responsiveness.In contrast, IL-2 augmented CCR2 expression and MCP-1 itself had no effect.These results suggest that, regulation of receptor expression in addition to agonist production is likely a crucial point in the regulation of the chemokine system.

View Article: PubMed Central - PubMed

Affiliation: Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.

ABSTRACT
The present study was designed to investigate the effect of bacterial lipopolysaccharide (LPS) on C-C chemokine receptors (CCR) expressed in human mononuclear phagocytes. LPS caused a rapid and drastic reduction of CCR2 mRNA levels, which binds MCP-1 and -3. CCR1 and CCR5 mRNAs were also reduced, though to a lesser extent, whereas CXCR2 was unaffected. The rate of nuclear transcription of CCR2 was not affected by LPS, whereas the mRNA half life was reduced from 1.5 h to 45 min. As expected, LPS-induced inhibition of CCR2 mRNA expression was associated with a reduction of both MCP-1 binding and chemotactic responsiveness. The capacity to inhibit CCR2 expression in monocytes was shared by other microbial agents and cytokines (inactivated Streptococci, Propionibacterium acnes, and to a lesser extent, IL-1 and TNF-alpha). In contrast, IL-2 augmented CCR2 expression and MCP-1 itself had no effect. These results suggest that, regulation of receptor expression in addition to agonist production is likely a crucial point in the regulation of the chemokine system.

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Effect of LPS on the  CCR2 (A), CCR1 (B), CCR5  (C) and CXCR2 (D) mRNA  expression: dose-response analysis. E shows the ethidium bromide stained ribosomal RNA. A  is representative of four different  donors. B and C are representative of two different donors. Total RNA was purified from fresh  human monocytes incubated for  4 h as indicated.
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Figure 1: Effect of LPS on the CCR2 (A), CCR1 (B), CCR5 (C) and CXCR2 (D) mRNA expression: dose-response analysis. E shows the ethidium bromide stained ribosomal RNA. A is representative of four different donors. B and C are representative of two different donors. Total RNA was purified from fresh human monocytes incubated for 4 h as indicated.

Mentions: Human monocytes express high levels of CCR1, CCR2, and CCR5 transcripts (Fig. 1). CCR3 and 4 were undetectable by Northern analysis under these conditions (not shown). Using either a CCR2A or a CCR2B cDNA–specific probes, we detected a single 3.4-kb transcript, as previously reported (23, 23a). As shown in Fig. 1, LPS induced a dosedependent inhibition of the steady state level of CCR2 mRNA after 4 h, with a dramatic inhibition already at 1 ng/ml (Fig. 1 A) and virtually complete suppression at increasing concentrations, 10 and 100 ng/ml. Removal of the LPS after 4 h resulted in a gradual and complete restoration of the CCR2 mRNA level in 24 h (data not shown). Similar results were obtained by using the CCR2A cDNA– specific probe (data not shown). Likewise, but to a lesser extent, a significant LPS-dependent reduction of the CCR1 (Fig. 1 B) and CCR5 (C) mRNA levels was observed. In contrast, the mRNA level of CXCR2 was unaffected (Fig. 1 D).


Bacterial lipopolysaccharide rapidly inhibits expression of C-C chemokine receptors in human monocytes.

Sica A, Saccani A, Borsatti A, Power CA, Wells TN, Luini W, Polentarutti N, Sozzani S, Mantovani A - J. Exp. Med. (1997)

Effect of LPS on the  CCR2 (A), CCR1 (B), CCR5  (C) and CXCR2 (D) mRNA  expression: dose-response analysis. E shows the ethidium bromide stained ribosomal RNA. A  is representative of four different  donors. B and C are representative of two different donors. Total RNA was purified from fresh  human monocytes incubated for  4 h as indicated.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196159&req=5

Figure 1: Effect of LPS on the CCR2 (A), CCR1 (B), CCR5 (C) and CXCR2 (D) mRNA expression: dose-response analysis. E shows the ethidium bromide stained ribosomal RNA. A is representative of four different donors. B and C are representative of two different donors. Total RNA was purified from fresh human monocytes incubated for 4 h as indicated.
Mentions: Human monocytes express high levels of CCR1, CCR2, and CCR5 transcripts (Fig. 1). CCR3 and 4 were undetectable by Northern analysis under these conditions (not shown). Using either a CCR2A or a CCR2B cDNA–specific probes, we detected a single 3.4-kb transcript, as previously reported (23, 23a). As shown in Fig. 1, LPS induced a dosedependent inhibition of the steady state level of CCR2 mRNA after 4 h, with a dramatic inhibition already at 1 ng/ml (Fig. 1 A) and virtually complete suppression at increasing concentrations, 10 and 100 ng/ml. Removal of the LPS after 4 h resulted in a gradual and complete restoration of the CCR2 mRNA level in 24 h (data not shown). Similar results were obtained by using the CCR2A cDNA– specific probe (data not shown). Likewise, but to a lesser extent, a significant LPS-dependent reduction of the CCR1 (Fig. 1 B) and CCR5 (C) mRNA levels was observed. In contrast, the mRNA level of CXCR2 was unaffected (Fig. 1 D).

Bottom Line: As expected, LPS-induced inhibition of CCR2 mRNA expression was associated with a reduction of both MCP-1 binding and chemotactic responsiveness.In contrast, IL-2 augmented CCR2 expression and MCP-1 itself had no effect.These results suggest that, regulation of receptor expression in addition to agonist production is likely a crucial point in the regulation of the chemokine system.

View Article: PubMed Central - PubMed

Affiliation: Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.

ABSTRACT
The present study was designed to investigate the effect of bacterial lipopolysaccharide (LPS) on C-C chemokine receptors (CCR) expressed in human mononuclear phagocytes. LPS caused a rapid and drastic reduction of CCR2 mRNA levels, which binds MCP-1 and -3. CCR1 and CCR5 mRNAs were also reduced, though to a lesser extent, whereas CXCR2 was unaffected. The rate of nuclear transcription of CCR2 was not affected by LPS, whereas the mRNA half life was reduced from 1.5 h to 45 min. As expected, LPS-induced inhibition of CCR2 mRNA expression was associated with a reduction of both MCP-1 binding and chemotactic responsiveness. The capacity to inhibit CCR2 expression in monocytes was shared by other microbial agents and cytokines (inactivated Streptococci, Propionibacterium acnes, and to a lesser extent, IL-1 and TNF-alpha). In contrast, IL-2 augmented CCR2 expression and MCP-1 itself had no effect. These results suggest that, regulation of receptor expression in addition to agonist production is likely a crucial point in the regulation of the chemokine system.

Show MeSH