Selective effects of Lactobacillus casei Shirota on T cell activation, natural killer cell activity and cytokine production

Modulation of host immunity is an important potential mechanism by which probiotics confer health benefits. This study was designed to investigate the effects of a probiotic strain, Lactobacillus casei Shirota (LcS), on immune function, using human peripheral blood mononuclear cells (PBMC) in vitro. In addition, the role of monocytes in LcS-induced immunity was also explored. LcS promoted natural killer (NK) cell activity and preferentially induced expression of CD69 and CD25 on CD8+ and CD56+ subsets in the absence of any other stimulus. LcS also induced production of IL-1β, IL-6, TNF-α, IL-12 and IL-10 in the absence of lipopolysaccharide (LPS). In the presence of LPS, LcS enhanced IL-1β production, but inhibited LPS-induced IL-10 and IL-6 production, and had no further effect on TNF-α and IL-12 production. Monocyte-depletion significantly reduced the impact of LcS on lymphocyte activation, cytokine production and NK cell activity. In conclusion, LcS preferentially activated cytotoxic lymphocytes in both the innate and specific immune system, which suggests that LcS could potentiate the destruction of infected cells in the body. LcS also induced both pro-inflammatory and anti-inflammatory cytokine production in the absence of LPS, but inhibited LPS-induced cytokine production in some cases. Monocytes play an important role in LcS-induced immunological responses.

Syk-Dependent Cytokine Induction by Dectin-1 Reveals a Novel Pattern Recognition Pathway for C Type Lectins

Pattern-recognition receptors (PRRs) detect molecular signatures of microbes and initiate immune responses to infection. Prototypical PRRs such as Toll-like receptors (TLRs) signal via a conserved pathway to induce innate response genes. In contrast, the signaling pathways engaged by other classes of putative PRRs remain ill defined. Here, we demonstrate that the β-glucan receptor Dectin-1, a yeast binding C type lectin known to synergize with TLR2 to induce TNFα and IL-12, can also promote synthesis of IL-2 and IL-10 through phosphorylation of the membrane proximal tyrosine in the cytoplasmic domain and recruitment of Syk kinase. syk−/− dendritic cells (DCs) do not make IL-10 or IL-2 upon yeast stimulation but produce IL-12, indicating that the Dectin-1/Syk and Dectin-1/TLR2 pathways can operate independently. These results identify a novel signaling pathway involved in pattern recognition by C type lectins and suggest a potential role for Syk kinase in regulation of innate immunity.

Short communication: Suppressor of cytokine signaling-2 mRNA increases after parturition in the liver of dairy cows

After parturition, the somatotropic axis of the dairy cow is uncoupled, partly because of reduced concentration of liver-specific GH receptor (GHR) 1A. Estradiol-17 beta (E-2) concentrations increase at parturition and E-2 upregulates suppressors of cytokine signaling-2 (SOCS-2) mRNA expression, potentially inhibiting GH signaling. Therefore, we hypothesized that SOCS-2 mRNA is upregulated after parturition. Multiparous Holstein cows (n = 18) were dried off 45 d before expected parturition and fed diets to meet nutrient requirements at ad libitum or limited dry matter intake during the dry period. All cows were fed the same diet ad libitum from calving until 4 wk after parturition. Blood samples were collected weekly and more frequently near parturition. Liver biopsies obtained at -21, -7, 2, and 28 d relative to parturition were assessed for SOCS-2 and GHR 1A mRNA by quantitative real-time reverse-transcription PCR. The relative amount of SOCS-2 mRNA increased after parturition with both treatments and was greater on d 2 for cows limit-fed during the dry period compared with cows fed at ad libitum dry matter intake. Plasma E2 concentrations increased on d -13, -5 and 1 relative to parturition and the increases were greater in limit-fed cows. Plasma GH concentration was greater for limit-fed cows and increased after parturition in all cows. The amount of GHR 1A mRNA did not differ between diets but decreased on d 2. In addition to reduced GHR 1A, increased SOCS-2 mRNA after parturition, perhaps because of increased E-2, may further uncouple GH signaling in the liver of the transition dairy cow.

Modulation of cytokine secretion by pentacyclic triterpenes from olive pomace oil in human mononuclear cells

Olive pomace oil, also known as "orujo" olive oil, is a blend of refined-pomace oil and virgin olive oil, fit for human consumption. Maslinic acid, oleanolic acid, erythrodiol, and uvaol are pentacyclic triterpenes, found in the non-glyceride fraction of orujo oil, which have previously been reported to have anti-inflammatory properties. In the present work, we investigated the effect of these minor components on pro-inflammatory cytokine production by human peripheral blood mononuclear cells in six different samples. Uvaol, erythrodiol, and oleanolic acid significantly decreased IL-1 beta and IL-6 production in a dose-dependent manner. All three compounds significantly reduced TNF-alpha production at 100 mu M; however, at 10 mu M, uvaol and oleanolic acid enhanced the generation of TNF-alpha. In contrast, maslinic acid did not significantly alter the concentration of those cytokines, with the exception of a slight inhibitory effect at 100 mu M. All four triterpenes inhibited production of I-309, at 50 mu M and 100 mu M. However, uvaol enhanced I-309 production at 10 mu M. The triterpenic dialcohols had a similar effect on MIG production. In conclusion, this study demonstrates that pentacyclic triterpenes in orujo oil exhibit pro- and anti-inflammatory properties depending on chemical structure and dose, and may be useful in modulating the immune response. (c) 2006 Elsevier Ltd. All rights reserved.

Degree of oxidation of low density lipoprotein affects expression of CD36 and PPAR gamma, but not cytokine production, by human monocyte-macrophages

Oxidized low-density lipoprotein (oxLDL) exhibits many atherogenic effects, including the promotion of monocyte recruitment to the arterial endothelium and the induction of scavenger receptor expression. However, while atherosclerosis involves chronic inflammation within the arterial intima, it is unclear whether oxLDL alone provides a direct inflammatory stimulus for monocyte-macrophages. Furthermore, oxLDL is not a single, well-defined entity, but has structural and physical properties which vary according to the degree of oxidation. We tested the hypothesis that the biological effects of oxLDL will vary according to its degree of oxidation and that some species of oxLDL will have atherogenic properties, while other species may be responsible for its inflammatory activity. The atherogenic and inflammatory properties of LDL oxidized to predetermined degrees (mild, moderate and extensive oxidation) were investigated in a single system using human monocyte-derived macrophages. Expression of CD36 mRNA was up-regulated by mildly- and moderately-oxLDL, but not highly-oxLDL. The expression of the transcription factor, proliferator-activated receptor-gamma (PPARgamma), which has been proposed to positively regulate the expression of CD36, was increased to the greatest degree by highly-oxLDL. However, the DNA binding activity of PPARgamma was increased only by mildly- and moderately-oxLDL. None of the oxLDL species appeared to be pro-inflammatory towards monocytes, either directly or indirectly through mediators derived from lymphocytes, regardless of the degree of oxidation. (C) 2003 Published by Elsevier Science Ireland Ltd.

Integrated cytokine and metabolic analysis of pathological responses to parasite exposure in rodents

Parasitic infections cause a myriad of responses in their mammalian hosts, on immune as well as on metabolic level. A multiplex panel of cytokines and metabolites derived from four parasite-rodent models, namely, Plasmodium berghei-mouse, Trypanosoma brucei brucei-mouse, Schistosoma mansoni-mouse, and Fasciola hepatica-rat were statistically coanalyzed. 1H NMR spectroscopy and multivariate statistical analysis were used to characterize the urine and plasma metabolite profiles in infected and noninfected animals. Each parasite generated a unique metabolic signature in the host. Plasma cytokine concentrations were obtained using the ‘Meso Scale Discovery’ multi cytokine assay platform. Multivariate data integration methods were subsequently used to elucidate the component of the metabolic signature which is associated with inflammation and to determine specific metabolic correlates with parasite-induced changes in plasma cytokine levels. For example, the relative levels of acetyl glycoproteins extracted from the plasma metabolite profile in the P. berghei-infected mice were statistically correlated with IFN-γ, whereas the same cytokine was anticorrelated with glucose levels. Both the metabolic and the cytokine data showed a similar spatial distribution in principal component analysis scores plots constructed for the combined murine data, with samples from all infected animals clustering according to the parasite species and whereby the protozoan infections (P. berghei and T. b. brucei) grouped separately from the helminth infection (S. mansoni). For S. mansoni, the main infection-responsive cytokines were IL-4 and IL-5, which covaried with lactate, choline, and D-3-hydroxybutyrate. This study demonstrates that the inherently differential immune response to single and multicellular parasites not only manifests in the cytokine expression, but also consequently imprints on the metabolic signature, and calls for in-depth analysis to further explore direct links between immune features and biochemical pathways.

Greater impact of dietary fat manipulation than apolipoprotein E genotype on ex-vivo cytokine production – insights from the SATgenε study

Apolipoprotein E (APOE) genotype is believed to play an important role in cardiovascular risk. APOE4 carriers have been associated with higher blood lipid levels and a more pro-inflammatory state compared with APOE3/E3 individuals. Although dietary fat composition has been considered to modulate the inflammatory state in humans, very little is known about how APOE genotype can impact on this response. In a follow-up to the main SATgene study, we aimed to explore the effects of APOE genotype, as well as, dietary fat manipulation on ex vivo cytokine production. Blood samples were collected from a subset of SATgene participants (n = 52/88), prospectively recruited according to APOE genotype (n = 26 E3/E3 and n = 26 E3/E4) after low-fat (LF), high saturated fat (HSF) and HSF with 3.45 g docosahexaenoic acid (DHA) dietary periods (each diet eight weeks in duration assigned in the same order) for the measurement of ex vivo cytokine production using whole blood culture (WBC). Concentrations of IL-1beta, IL-6, IL-8, IL-10 and TNF-alpha were measured in WBC supernatant samples after stimulation for 24 h with either 0.05 or 1 lg/ml of bacterial lipopolysaccharide (LPS). Cytokine levels were not influenced by genotype, whereas, dietary fat manipulation had a significant impact on TNF-a and IL-10 production; TNF-a concentration was higher after consumption of the HSF diet compared with baseline and the LF diet (P < 0.05), whereas, IL-10 concentration was higher after the LF diet compared with baseline (P < 0.05). In conclusion, our study has revealed the amount and type of dietary fat can significantly modulate the production of TNF-a and IL-10 by ex vivo LPS-stimulated WBC samples obtained from normolipidaemic subjects.

Microbial Recognition Via Toll-Like Receptor-Dependent and -Independent Pathways Determines the Cytokine Response of Murine Dendritic Cell Subsets to CD40 Triggering

Dendritic cells (DC) can produce Th-polarizing cytokines and direct the class of the adaptive immune response. Microbial stimuli, cytokines, chemokines, and T cell-derived signals all have been shown to trigger cytokine synthesis by DC, but it remains unclear whether these signals are functionally equivalent and whether they determine the nature of the cytokine produced or simply initiate a preprogrammed pattern of cytokine production, which may be DC subtype specific. Here, we demonstrate that microbial and T cell-derived stimuli can synergize to induce production of high levels of IL-12 p70 or IL-10 by individual murine DC subsets but that the choice of cytokine is dictated by the microbial pattern recognition receptor engaged. We show that bacterial components such as CpG-containing DNA or extracts from Mycobacterium tuberculosis predispose CD8alpha(+) and CD8alpha(-)CD4(-) DC to make IL-12 p70. In contrast, exposure of CD8alpha(+), CD4(+) and CD8alpha(-)CD4(-) DC to heat-killed yeasts leads to production of IL-10. In both cases, secretion of high levels of cytokine requires a second signal from T cells, which can be replaced by CD40 ligand. Consistent with their differential effects on cytokine production, extracts from M. tuberculosis promote IL-12 production primarily via Toll-like receptor 2 and an MyD88-dependent pathway, whereas heat-killed yeasts activate DC via a Toll-like receptor 2-, MyD88-, and Toll/IL-1R domain containing protein-independent pathway. These results show that T cell feedback amplifies innate signals for cytokine production by DC and suggest that pattern recognition rather than ontogeny determines the production of cytokines by individual DC subsets.

Secoiridoids delivered as olive leaf extract induce acute improvements in human vascular function and reduction of an inflammatory cytokine: a randomised, double-blind, placebo-controlled, cross-over trial

The leaves of the olive plant (Olea europaea) are rich in polyphenols, of which oleuropein and hydroxytyrosol (HT) are most characteristic. Such polyphenols have been demonstrated to favourably modify a variety of cardiovascular risk factors. The aim of the present intervention was to investigate the influence of olive leaf extract (OLE) on vascular function and inflammation in a postprandial setting and to link physiological outcomes with absorbed phenolics. A randomised, double-blind, placebo-controlled, cross-over, acute intervention trial was conducted with eighteen healthy volunteers (nine male, nine female), who consumed either OLE (51 mg oleuropein; 10mg HT), or a matched control (separated by a 4-week wash out) on a single occasion. Vascular function was measured by digital volume pulse (DVP), while blood collected at baseline, 1, 3 and 6 h was cultured for 24 h in the presence of lipopolysaccharide in order to investigate effects on cytokine production. Urine was analysed for phenolic metabolites by HPLC. DVP-stiffness index and ex vivo IL-8 production were significantly reduced (P < 0.05) after consumption of OLE compared to the control. These effects were accompanied by the excretion of several phenolic metabolites, namely HT and oleuropein derivatives, which peaked in urine after 8-24 h. The present study provides the first evidence that OLE positively modulates vascular function and IL-8 production in vivo, adding to growing evidence that olive phenolics could be beneficial for health.