In:
Frontiers in Immunology, Frontiers Media SA, Vol. 12 ( 2021-5-25)
Abstract:
The lipopolysaccharides (LPSs) of Rhodobacter are reported to be TLR4 antagonists. Accordingly, the extract of Rhodobacter azotoformans (RAP99) is used as a health supplement for humans and animals in Japan to regulate immune responses in vivo . We previously analyzed the LPS structure of RAP99 (RAP99-LPS) and found it is different from that of E. coli -LPS but similar to lipid A from Rhodobacter sphaeroides (RSLA), a known antagonist of TLR4, with both having three C14 fatty acyl groups, two C10 fatty acyl groups, and two phosphates. Here we show that RAP99-LPS has an immune stimulatory activity and acts as a TLR4 agonist. Pretreatment of RAP99-LPS suppressed E. coli -LPS-mediated weight loss, suggesting it is an antagonist against E. coli -LPS like other LPS isolated from Rhodobacter . However, injections of RAP99-LPS caused splenomegaly and increased immune cell numbers in C57BL/6 mice but not in C3H/HeJ mice, suggesting that RAP99-LPS stimulates immune cells via TLR4. Consistently, RAP99-LPS suppressed the lung metastasis of B16F1 tumor cells and enhanced the expression of TLR3-mediated chemokines. These results suggest that RAP99-LPS is a TLR4 agonist that enhances the activation status of the immune system to promote anti-viral and anti-tumor activity in vivo .
Type of Medium:
Online Resource
ISSN:
1664-3224
DOI:
10.3389/fimmu.2021.675909
DOI:
10.3389/fimmu.2021.675909.s001
DOI:
10.3389/fimmu.2021.675909.s002
DOI:
10.3389/fimmu.2021.675909.s003
DOI:
10.3389/fimmu.2021.675909.s004
DOI:
10.3389/fimmu.2021.675909.s005
DOI:
10.3389/fimmu.2021.675909.s006
Language:
Unknown
Publisher:
Frontiers Media SA
Publication Date:
2021
detail.hit.zdb_id:
2606827-8
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