Rhodobacter azotoformans LPS (RAP99-LPS) Is a TLR4 Agonist That Inhibits Lung Metastasis and Enhances TLR3-Mediated Chemokine Expression.
Front Immunol
; 12: 675909, 2021.
Article
em En
| MEDLINE
| ID: mdl-34113349
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.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Lipopolissacarídeos
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Rhodobacter
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Quimiocinas
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Receptor 3 Toll-Like
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Receptor 4 Toll-Like
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Neoplasias Pulmonares
Limite:
Animals
Idioma:
En
Revista:
Front Immunol
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Japão
País de publicação:
CH
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SUIZA
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SUÍÇA
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SWITZERLAND