Differential regulation of toll-like receptors by pro- and anti-inflammatory cytokines between human intestinal epithelial and monocytic cell lines

ABSTRACT We previously showed that heat-killed Borrelia burgdorferi spirochetes and lipidated outer surface protein A (L-OspA) stimulated the in vitro production of interleukin-10 (IL-10) in peripheral blood mononuclear cells (PBMC) from uninfected humans and rhesus monkeys (G. Giambartolomei et al., Infect. Immun. 66:2691–2697, 1998). Here we demonstrate that uninfected human peripheral blood monocytes, but not B or T cells, are the cells that transcribe the IL-10 cytokine gene in response to heat-killed B. burgdorferi. B. burgdorferi similarly induced an upregulation of the IL-1β and IL-6 cytokine genes in monocytes and the production of IL-10 and IL-6 in culture supernatants of the human monocytic cell line THP-1. Purified L-OspA (but not unlipidated OspA [U-OspA] or U-OspC) also stimulated the production of both cytokines in THP-1 cells in a dose-dependent fashion, suggesting that acylation of the OspA protein molecule is required for the production of both anti- and pro-inflammatory cytokines in naive monocytes. A lipohexapeptide that contained the tripalmitoyl-modified cysteine motif (Pam3Cys-Hex) of B. burgdorferi lipoproteins but with an arbitrary peptide sequence had the same effect. Monoclonal antibodies (MAbs) MY4 and 60bca, both of which bind to CD14 and are known to block lipopolysaccharide (LPS)-mediated cytokine production, were able to block L-OspA-mediated IL-10 and IL-6 cytokine production. In contrast, MAb 26ic, which also binds to CD14 but does not block LPS function, failed to inhibit L-OspA-mediated cytokine production. These data suggest that activation of monocytes and production of both anti- and pro-inflammatory cytokines induced by lipoproteins proceeds via the CD14 receptor. LPS binding protein was not required for OspA-induced cytokine production. Our results demonstrate that pro- and anti-inflammatory cytokines induced by B. burgdorferilipoproteins in PBMC are produced by monocytes and that lipoprotein and LPS signaling pathways share at least the initial signaling event that involves the CD14 receptor.

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Immunomodulatory effects of thymol and cinnamaldehyde in chicken cell lines

Journal of Applied Animal Nutrition ◽

10.3920/jaan2020.0001 ◽

2020 ◽

Vol 8 (1) ◽

pp. 21-30 ◽

Cited By ~ 1

Author(s):

C. Shen ◽

L.G. Christensen ◽

S.Y. Bak ◽

N. Christensen ◽

K. Kragh

Keyword(s):

Cell Lines ◽

Inflammatory Cytokines ◽

Membrane Integrity ◽

Feed Additives ◽

Dependent Manner ◽

Gut Health ◽

Phagocytic Capacity ◽

Chicken Cell ◽

Anti Inflammatory ◽

Lmh Cells

Thymol and cinnamaldehyde are phytogenic feed additives that have been developed to improve gut health, immunity and growth performance in poultry and swine. This study evaluated the immune modulating effects of a thymol and cinnamaldehyde blend (TCB) in the intestinal system of poultry in vitro, using two chicken cell lines, LMH (liver cell line) which has been used to mimic epithelial cell responses, and HD-11 (monocyte/macrophage-like). Cells with high viability (>95%) from established cell lines were cultured in the presence of TCB at concentrations ranging from 1 ng/ml to 100 ng/ml. The viability, transepithelial electrical resistance (TEER) and phagocytic capacity of co-cultured LMH cells, with or without stimulation with lipopolysaccharide (LPS), was subsequently evaluated. The expression of cytokines, chemokines and pattern recognition receptors by HD-11 monocytes/macrophages was measured by RT-PCR and by proteomic analysis. TCB was well tolerated by both cell lines (cell viability >90% after co-culture with TCB at 100 ng/ml for 48 h with or without LPS). Epithelial integrity of LMH cells (as assessed by TEER) was increased by TCB (10 ng/ml) after 4 h incubation, versus untreated controls, and phagocytic capacity of HD-11 cells was increased, in a dose-dependent manner (P<0.05). In HD-11 cells, TCB (10 ng/ml) downregulated the relative expression of pro-inflammatory cytokines interleukin (IL)-1β, IL-6, IL-8 and the transcription factor cyclooxygenase-2 and upregulated expression of anti-inflammatory IL-10, versus untreated controls (P<0.05). In summary, under the tested conditions, TCB enhanced the epithelial barrier integrity of poultry hepatocytes, increased phagocytic activity and production of anti-inflammatory cytokines by monocytes and macrophages. These results indicated how supplementing TCB in poultry diets can increase bird performance, by increasing in vivo cell membrane integrity (especially important in the gut) and assisting in immune responses, which can liberate energy for growth.

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