Interactions in the mucosal microenvironment: vasoactive intestinal peptide modulates the down-regulatory action ofLactobacillus rhamnosuson LPS-induced interleukin-8 production by intestinal epithelial cells

Abstract

Intestinal epithelial cells (IECs) act as a key point of initial contact with bacteria in the microenvironment of the intestinal tract. Interactions between IECs and bacteria lead to alterations in IEC activity, including modified cytokine secretion patterns, which may influence the mucosal immune response. IECs respond to lipopolysaccharide (LPS) from gramnegative bacteria by production of pro-inflammatory cytokines, including interleukin-8 (IL-8). Two strains of Lactobacillus rhamnosus , R0011 and R0049, were able to down-regulate LPS-induced IL-8 production by the human IEC line HT-29. Similar results were seen with KATO III gastric epithelial cells, suggesting a possible route for anti-inflammatory actions by L. rhamnosus . To further explore potential interactions in the gastrointestinal mucosal microenvironment, the effects of the neuropeptide vasoactive intestinal peptide (VIP) on the actions of L. rhamnosus R0011 were examined. VIP blocked the ability of this strain to down-regulate both constitutive and LPS-induced IL-8 production, suggesting that interactions between lactic acid bacteria (LAB) and IECs can be influenced by neuropeptides released into intestinal tissues. High levels of protein kinase A (PKA) and protein kinase C (PKC) activation rendered IEC refractory to the down-regulatory effects of L. rhamnosus on IL-8 production. L. rhamnosus R0011 induces moderate elevation of intracellular cAMP levels, indicating that its actions may, at least in part, be mediated through this signalling pathway in IECs.

Short-Chain Fatty Acids Regulate Secretion of IL-8 from Human Intestinal Epithelial Cell Lines in vitro

“…We hypothesised that SCFAs may regulate secretion of IL-8, which has been reported to be produced by human normal IECs and adenocarcinoma derived cell line such as HT-29 cells (Daig et al, 2000;Kolios et al, 1996;Li et al, 2001;Yomogida et al, 2008). IL-8 acts as a chemoattractant of neutrophils to the site of inflammation leading to accumulation and infiltration of immune cells at the site of inflammation and may cause tissue damage (Schuerer-Maly et al, 1994;Wood et al, 2007). IL-8 has also been implicated in tumorigenesis, increasing the expression of IL-8 and/or its receptors may enhance tumour cell proliferation, promote angiogenesis and induce tumourassociated macrophages to release more growth factors leading to cancer cell invasion at the tumour site (Lee et al, 2013;Ning & Lenz 2012;Waugh & Wilson 2008).…”

“…Based on this hypothesis, we initially determined viability of cells and the toxicity effects of mixed SCFAs at physiological concentrations in the lumen of human colon (Cummings et al, 1987;Kiefer et al, 2006;Treem et al, 1994). Similar concentrations were therefore used in IEC stimulation (Wood et al, 2007). The presence of SCFAs improved the growth of T4056 cells likely due to the provision of energy source by SCFAs (Kiefer et al, 2006;Wachtershauser & Stein 2000;Matthews et al, 2012).…”

“…However, in those studies the cell stimulation was achieved by priming of IECs with inflammatory cytokines, such as IFN-g prior to activating them with LPS (Angrisano et al, 2010). The use of LPS alone as a stimulant of IECs to release IL-8 (Wood et al, 2007) depends on the cell type and expression of LPS receptors as well as time and dose of stimulation (Schuerer-Maly et al, 1994;Suzuki et al, 2003;Thorley et al, 2007).…”

A comprehensive post-market review of studies on a probiotic product containing Lactobacillus helveticus R0052 and Lactobacillus rhamnosus R0011

“…Human HT-29 or KATO III (gastric adenocarcinoma cells) stimulated with lipopolysaccharide derived from Escherichia coli yield a strong pro-inflammatory response as characterised by increased levels of interleukin-8 (IL- Dupont et al, 2000;Pham et al, 2000;Van Calsteren et al, 2002;Provencher et al, 2003;Peant et al, 2005R-11 Botes et al, 2008R-011 Roy and Ward, 2004R0052 I-1722Possemiers et al, 2010K1 Podlesny et al, 2011K300 Atassi et al, 2006Rosell-52 Diop et al, 2008Lactobacillus acidophilus YS or RO-52 Easo et al, 2002 8) (Wood et al, 2007). In these cell systems, R0011 was able to significantly reduce the levels of IL-8.…”

“…In these cell systems, R0011 was able to significantly reduce the levels of IL-8. This outcome suggested that high levels of induction of protein kinases render human intestinal epithelial cells refractory to the modulatory effects of the L. rhamnosus R0011 (Wood et al, 2007). VIP is known to induce protein kinase A and elevate cAMP.…”