Article

Aberrant inflammatory response to Streptococcus pyogenes in mice lacking myeloid differentiation factor 88.

Department of Microbial Pathogenesis, Infection Immunology Research Group, Helmholtz Centre for Infection Research, D-38124 Braunschweig, Germany.
American Journal Of Pathology (impact factor: 4.89). 12/2009; 176(2):754-63. DOI:10.2353/ajpath.2010.090422 pp.754-63
Source: PubMed

ABSTRACT Several in vitro studies have emphasized the importance of toll-like receptor/myeloid differentiation factor 88 (MyD88) signaling in the inflammatory response to Streptococcus pyogenes. Since the extent of inflammation has been implicated in the severity of streptococcal diseases, we have examined here the role of toll-like receptor/MyD88 signaling in the pathophysiology of experimental S. pyogenes infection. To this end, we compared the response of MyD88-knockout (MyD88(-/-)) after subcutaneous inoculation with S. pyogenes with that of C57BL/6 mice. Our results show that MyD88(-/-) mice harbored significantly more bacteria in the organs and succumbed to infection much earlier than C57BL/6 animals. Absence of MyD88 resulted in diminished production of inflammatory cytokines such as interleukin-12, interferon-gamma, and tumor necrosis factor-alpha as well as chemoattractants such as monocyte chemotactic protein-1 (MCP-1) and Keratinocyte-derived chemokine (KC), and hampered recruitment of effector cells involved in bacterial clearance (macrophages and neutrophils) to the infection site. Furthermore, MyD88(-/-) but not C57BL/6 mice exhibited a massive infiltration of eosinophils in infected organs, which can be explained by an impaired production of the regulatory chemokines, gamma interferon-induced monokine (MIG/CXCL9) and interferon-induced protein 10 (IP-10/CXCL10), which can inhibit transmigration of eosinophils. Our results indicate that MyD88 signaling targets effector cells to the site of streptococcal infection and prevents extravasation of cells that can induce tissue damage. Therefore, MyD88 signaling may be important for shaping the quality of the inflammatory response elicited during infection to ensure optimal effector functions.

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Keywords

C57BL/6 mice exhibited
 
effector cells
 
experimental S. pyogenes infection
 
gamma interferon-induced monokine
 
impaired production
 
infection site
 
inflammatory response elicited
 
interferon-induced protein 10
 
massive infiltration
 
MyD88 signaling
 
MyD88 signaling targets effector cells
 
optimal effector functions
 
regulatory chemokines
 
S. pyogenes
 
streptococcal infection
 
Streptococcus pyogenes
 
toll-like receptor/MyD88 signaling
 
toll-like receptor/myeloid differentiation factor 88
 
tumor necrosis factor-alpha
 
vitro studies