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Mannan-binding lectin reduces CpG DNA-induced inflammatory cytokine production by human monocytes
1Department of Immunology, Southern Medical University, Guangzhou, 510515.
Abstract:
Mannan-binding lectin (MBL) belongs to the collectin family and functions as an opsonin that can also initiate complement activation. Our previous study showed that MBL serves as a double-stranded RNA binding protein that attenuates polyriboinosinic-polyribocytidylic acid-induced TLR3 activation. Prompted by these findings, in the present study cross-talk between MBL and CpG-DNA-induced TLR9 activation was investigated. Here, it was found that MBL also interacts with the TLR9 agonist, CpG oligodeoxynucleotide (CpG-ODN), in a calcium-dependent manner. Purified MBL protein suppressed activation of nuclear factor-kappa B signaling and subsequent production of proinflammatory cytokines from human monocytes induced by CpG-ODN 2006. These observations indicate that MBL can down-regulate CpG DNA-induced TLR9 activation, emphasizing the importance of understanding the interaction of MBL with TLR agonist in host immune defense.
Insights
Mannan-binding lectin (MBL) binds to CpG-DNA and suppresses Toll-like receptor 9 (TLR9) activation. This interaction down-regulates inflammatory responses, highlighting MBL's role in immune defense.
Area of Science:
- Immunology
- Molecular Biology
Background:
- Mannan-binding lectin (MBL) is a collectin family member functioning as an opsonin and complement activator.
- Previous research identified MBL as a double-stranded RNA binding protein that inhibits TLR3 activation.
Purpose of the Study:
- To investigate the interaction between MBL and Toll-like receptor 9 (TLR9) activation by CpG-DNA.
- To determine if MBL modulates TLR9 signaling pathways.
Main Methods:
- Investigated the binding of MBL to CpG oligodeoxynucleotides (CpG-ODN).
- Assessed the effect of MBL on nuclear factor-kappa B (NF-κB) signaling and cytokine production in human monocytes stimulated with CpG-ODN.
Main Results:
- MBL was found to interact with CpG-ODN in a calcium-dependent manner.
- Purified MBL protein suppressed NF-κB activation and pro-inflammatory cytokine release induced by CpG-ODN 2006 in human monocytes.
Conclusions:
- MBL down-regulates CpG-DNA-induced TLR9 activation.
- Understanding MBL's interaction with TLR agonists is crucial for comprehending host immune defense mechanisms.
