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Interleukin-6 production by human neonatal monocytes stimulated by type III group B streptococci
J G Vallejo1, C J Baker, M S Edwards
1Departments of Pediatrics and of Microbiology and Immunology, Baylor College of Medicine, Houston, Texas 77030, USA.
Abstract:
The subcellular components of type III group B streptococci (GBS) that contribute to the host inflammatory response were determined by measuring production of the proinflammatory cytokine interleukin (IL)-6 by cord blood monocytes. Monocytes were stimulated with encapsulated (COH1) or unencapsulated (COH1-13) whole type III GBS or with purified GBS components, including type III capsular polysaccharide (III-PS), group B antigen (GB-Ag), lipoteichoic acid (LTA), or Escherichia coli lipopolysaccharide. Monocytes exposed to COH1 and COH1-13 released similar amounts of IL-6. GBS III-PS, GB-Ag, and LTA each induced IL-6. However, IL-6 release by monocytes was significantly greater after stimulation by GB-Ag than by III-PS or LTA (P < .05). Sera from 16 neonates with systemic GBS disease had IL-6 levels of 8 pg/mL to 4.28 ng/mL. GB-Ag is a potent inducer of IL-6 and may play an important role in tissue inflammation during GBS infection.
Insights
Group B Streptococcus (GBS) components were tested for their ability to trigger inflammation. Group B antigen (GB-Ag) strongly induced interleukin-6 (IL-6), suggesting its key role in GBS infections.
Area of Science:
- Immunology
- Microbiology
- Neonatal Research
Background:
- Group B Streptococcus (GBS) is a major cause of neonatal infections.
- Understanding GBS components that elicit host inflammatory responses is crucial for developing targeted therapies.
Purpose of the Study:
- To identify specific GBS subcellular components responsible for inducing the host inflammatory cytokine, interleukin-6 (IL-6).
- To assess the relative potency of different GBS components in stimulating IL-6 production by human monocytes.
Main Methods:
- Cord blood monocytes were stimulated with whole GBS strains (encapsulated and unencapsulated) or purified GBS components (type III capsular polysaccharide [III-PS], group B antigen [GB-Ag], lipoteichoic acid [LTA]).
- Interleukin-6 (IL-6) production by monocytes was measured.
- IL-6 levels in sera from neonates with systemic GBS disease were analyzed.
Main Results:
- Both encapsulated and unencapsulated GBS induced IL-6 production.
- Purified GBS components III-PS, GB-Ag, and LTA all stimulated IL-6 release.
- Group B antigen (GB-Ag) induced significantly higher IL-6 levels compared to III-PS and LTA (P < .05).
- Elevated IL-6 levels were observed in neonates with systemic GBS disease.
Conclusions:
- Group B antigen (GB-Ag) is a potent inducer of IL-6.
- GB-Ag likely plays a significant role in driving tissue inflammation during GBS infections.
- Further research into GB-Ag's role could inform therapeutic strategies against GBS disease.