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Soluble non-cross-linked peptidoglycan polymers stimulate monocyte-macrophage inflammatory functions
Abstract:
Soluble non-cross-linked peptidoglycan polymers are released by gram-positive bacteria when beta-lactam antibiotics are administered to humans. In this report, we show that this type of peptidoglycan can stimulate monocyte-macrophage functions that cause inflammation. Non-cross-linked peptidoglycan polymers from penicillin-treated Streptococcus faecium were purified and shown to stimulate the production of interleukin 1 by human monocytes and of colony-stimulating factors by a murine macrophage cell line. In addition, the release of plasminogen activator by human monocytes was inhibited by the soluble peptidoglycan. These in vitro results suggest that prolonged treatment with beta-lactam antibiotics, by causing the production of soluble peptidoglycan, may result in interleukin 1-mediated inflammatory reactions, excessive production of monocytes and granulocytes, and increased fibrin deposition.
Insights
Beta-lactam antibiotics can cause gram-positive bacteria to release soluble peptidoglycans, which may trigger inflammatory responses. These peptidoglycans stimulate immune cells, potentially leading to inflammation and increased white blood cell production.
Area of Science:
- Immunology
- Microbiology
- Pharmacology
Background:
- Gram-positive bacteria release soluble non-cross-linked peptidoglycan polymers when treated with beta-lactam antibiotics.
- These peptidoglycans are known to interact with host immune systems.
Purpose of the Study:
- To investigate the immunomodulatory effects of soluble peptidoglycans released by beta-lactam antibiotic-treated bacteria.
- To determine if these peptidoglycans stimulate or inhibit key immune cell functions.
Main Methods:
- Purification of non-cross-linked peptidoglycan polymers from penicillin-treated Streptococcus faecium.
- In vitro assays measuring cytokine production (interleukin-1, colony-stimulating factors) by human monocytes and murine macrophages.
- Assays assessing the effect of soluble peptidoglycans on plasminogen activator release from human monocytes.
Main Results:
- Purified soluble peptidoglycans stimulated interleukin-1 production in human monocytes.
- These peptidoglycans also stimulated colony-stimulating factor production in a murine macrophage cell line.
- Soluble peptidoglycans inhibited the release of plasminogen activator by human monocytes.
Conclusions:
- Soluble peptidoglycans released during beta-lactam antibiotic treatment can activate monocyte-macrophage functions, promoting inflammation.
- These findings suggest a mechanism by which prolonged beta-lactam use may lead to interleukin-1-mediated inflammation, altered monocyte/granulocyte production, and increased fibrin deposition.