Vasoactive intestinal peptide (VIP) differentially affects inflammatory immune responses in human monocytes infected with viable Salmonella or stimulated with LPS

Askar, Basim Ali; Ibrahim, Hiba; Barrow, Paul; Foster, Neil

Abstract

We compared the effect of VIP on human blood monocytes infected with Salmonella typhimurium 4/74 or stimulated with LPS. VIP (10−7 M) increased monocyte viability by 24% and 9% when cultured for 24 h with 4/74 or Salmonella LPS (100 ng/ml), respectively. Significantly increased (P < 0.05) numbers of 4/74 were also recovered from monocytes co-cultured with VIP after 6 h post-infection (pi) and this remained high after 24 h pi. Both 4/74 and LPS increased (P < 0.05) the concentration of TNF-α, IL-1β and IL-6 measured in monocyte supernatants. However, LPS induced this effect more rapidly while, with the exception of IL-6, 4/74 induced higher concentrations (P < 0.05). VIP significantly decreased (P < 0.05) TNF-α and IL-1β production by 4/74-infected monocytes after 6 pi, but only after 24 h in LPS-cultured monocytes. This trend was reversed for IL-6 production. However, TNF-α and IL-1β production by 4/74-infected monocytes, cultured with VIP, still remained higher (P < 0.05) than concentrations measured in supernatants cultured only with LPS. VIP also increased (P < 0.05) production of anti-inflammatory IL-10 in both 4/74 and LPS cultures after 24 h. We also show a differential effect of VIP on the expression of TNFα and IL-6 receptors, since VIP was only able to decreased expression in LPS-stimulated monocytes but not in 4/74-infected monocytes.

In conclusion, we show a differential effect of VIP on human monocytes infected with virulent Salmonella or stimulated with LPS. Our study suggests that the use of VIP in bacteraemia and/or sepsis may be limited to an adjunctive therapy to antibiotic treatment.

Citation

Askar, B. A., Ibrahim, H., Barrow, P., & Foster, N. (2015). Vasoactive intestinal peptide (VIP) differentially affects inflammatory immune responses in human monocytes infected with viable Salmonella or stimulated with LPS. Peptides, 71, https://doi.org/10.1016/j.peptides.2015.06.009

• Journal Article Type: Article
• Acceptance Date: Jun 16, 2015
• Online Publication Date: Jul 20, 2015
• Publication Date: Sep 30, 2015
• Deposit Date: Mar 27, 2017
• Publicly Available Date: Mar 27, 2017
• Journal: Peptides
• Print ISSN: 0196-9781
• Electronic ISSN: 1873-5169
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 71
• DOI: https://doi.org/10.1016/j.peptides.2015.06.009
• Keywords: VIP; Human monocytes; Salmonella
• Public URL: https://nottingham-repository.worktribe.com/output/760157
• Publisher URL: https://doi.org/10.1016/j.peptides.2015.06.009
• Contract Date: Mar 27, 2017