Differential binding of bacterial lipopolysaccharide to bovine peripheral-blood leukocytes

Anti-inflammatory and Anti-oxidative Effects of Phytohustil® and Root Extract of Althaea officinalis L. on Macrophages in vitro

Introduction

The medicinal plant marshmallow Althaea officinalis L. (A. officinalis), is used for the treatment of cough since centuries. Application of medicinal extracts of marshmallow roots shows immediate effects like a protective film on the inflamed mucosa. Because the soothing layer reduce irritation of the mucous system, a faster regeneration is supported by defense mechanisms required to protect the respiratory tract from environmental injury. Macrophages (MΦ), which belong to a group of multipurpose defensive cells, provide the first line of defense against mucosal invasive pathogens. The present study was performed to investigate, whether the herbal medicinal product has anti-inflammatory or anti-oxidative effects on pro-inflammatorily activated MΦ or after oxidative stress induction. Special attention should be payed to elucidate the effects of A. officinalis on the mechanism of intracellular defense as well as on migratory capacity of the MΦ.

Results

Treatment of PMA-differentiated human THP-1 MΦ with Phytohustil^® increased their viability without affecting the cell number. Phytohustil^® or root extracts of A. officinalis (REAo) – an active component of Phytohustil^® – were able to protect human MΦ against H₂O₂-induced cytotoxicity and H₂O₂-induced ROS production. Phytohustil^®, REAo or diclofenac used as anti-inflammatory reference substance, inhibited the LPS-induced release of tumor necrosis factor-alpha (TNF-α) as well as of IL6 in MΦ. Treatment with Phytohustil^®, its excipients or REAo did not impair the mitochondrial membrane potential (MMP). Finally, Phytohustil^® and REAo activated the migratory capacity of MΦ.

Conclusion

The present in vitro investigations indicate protective, i.e., anti-oxidative and anti-inflammatory effects of REAo and Phytohustil^®, additionally improving the migratory capacity of MΦ. These antiinflammatory effects were similar or even better than diclofenac. Thus, our data support and may explain the positive effect of Phytohustil^® observed in patients during the therapy of inflamed buccal mucosal membranes or treatment of cough.

Krill Oil-In-Water Emulsion Protects against Lipopolysaccharide-Induced Proinflammatory Activation of Macrophages In Vitro

Background: Parenteral nutrition is often a mandatory therapeutic strategy for cases of septicemia. Likewise, therapeutic application of anti-oxidants, anti-inflammatory therapy, and endotoxin lowering, by removal or inactivation, might be beneficial to ameliorate the systemic inflammatory response during the acute phases of critical illness. Concerning anti-inflammatory properties in this setting, omega-3 fatty acids of marine origin have been frequently described. This study investigated the anti-inflammatory and LPS-inactivating properties of krill oil (KO)-in-water emulsion in human macrophages in vitro. Materials and Methods: Differentiated THP-1 macrophages were activated using specific ultrapure-LPS that binds only on the toll-like receptor 4 (TLR4) in order to determine the inhibitory properties of the KO emulsion on the LPS-binding capacity, and the subsequent release of TNF-α. Results: KO emulsion inhibited the macrophage binding of LPS to the TLR4 by 50% (at 12.5 µg/mL) and 75% (at 25 µg/mL), whereas, at 50 µg/mL, completely abolished the LPS binding. Moreover, KO (12.5 µg/mL, 25 µg/mL, or 50 µg/mL) also inhibited (30%, 40%, or 75%, respectively) the TNF-α release after activation with 0.01 µg/mL LPS in comparison with LPS treatment alone. Conclusion: KO emulsion influences the LPS-induced pro-inflammatory activation of macrophages, possibly due to inactivation of the LPS binding capacity.

CD14 and tissue factor expression by bacterial lipopolysaccharide-stimulated bovine alveolar macrophages in vitro

The membrane-associated CD14 receptor (mCD14) is a monocyte/macrophage differentiation antigen, and it has been demonstrated to serve as a receptor for bacterial lipopolysaccharide (LPS; endotoxin). Binding of LPS to mCD14 has been shown to be associated with LPS-induced macrophage, monocyte, and neutrophil activation in humans. In this report, we describe the presence and function of an mCD14-like receptor on bovine alveolar macrophages (bAM). An immunofluorescence technique and flow cytometric analysis indicated binding of anti-human CD14 monoclonal antibodies (MAb) My4, 3C10, and 60bd to bAM. Binding of anti-CD14 MAb (3C10 and MY4) was reduced over 20% by pretreatment of bAM with phosphatidylinositol-specific phospholipase C (0.5 to 1.0 U/ml), indicating that bovine mCD14 is a glycosyl phosphatidylinositol-anchored protein. In addition, pretreatment of bAM with anti-CD14 MAb decreased binding of 125I-labeled LPS to macrophages, suggesting that bovine mCD14 serves as a receptor for LPS. A cDNA probe based on the human sequence for CD14 was used in Northern (RNA) blot analysis, and hybridization to human monocyte CD14 yielded the expected 1.5-kb band. Hybridization to bovine mRNA yielded a 1.5-kb band plus an unexpected 3.1-kb band. Constitutive expression of bovine CD14 mRNA was observed, and the expression level was modestly elevated in bAM stimulated for 24 h with LPS (1 ng/ml) in the presence of bovine serum. The function and activation of bAM were assessed by quantitation of tissue factor (TF) expression on the cells using an activated factor X-related chromogenic assay and S-2222 substrate. LPS (1 ng/ml)-mediated upregulation of TF expression on bAM was dependent on the presence of bovine serum components, and TF expression was inhibited by anti-CD14 MAb. In addition, TF mRNA levels in LPS-stimulated bAM were decreased by pretreatment of cells with anti-CD14 MAb (MAb 60bd, 10 micrograms/ml).

Signal transduction pathways of bacterial lipopolysaccharide-stimulated bovine vascular endothelial cells

Increased procoagulant activity of vascular endothelial cells may be an important component in the pathogenesis of intravascular coagulation associated with gram-negative bacterial diseases. Two bovine endothelial cell (BEC) lines isolated from pulmonary arteries (ENS-2 and ENT-18) were used in this study to investigate procoagulant signal transduction pathways of endotoxin (lipopolysaccharide, LPS)--stimulated BECs. The endothelial cell line ENS-2 was sensitive to LPS as demonstrated by tissue factor (TF) expression, but in contrast, the ENT-18 endothelial cell line was unusually resistant to the effects of LPS. No remarkable quantitative difference in binding of radiolabeled LPS was detected between the two endothelial cell lines. A protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate, PMA) failed to induce TF expression in either cell line at concentrations ranging from 0.05 to 1.00 microM when used as a sole stimulus for the endothelial cells. However, when PMA was used in combination with LPS, PMA enhanced the stimulatory effect of LPS on the endothelial cells. In parallel experiments, PKC inhibitors (H-7 and GF 109203X) interfered with the stimulatory effect of LPS on the cells by decreasing tissue factor expression. We also found that an activator of adenylate cyclase, forskolin, similarly inhibited LPS-induced tissue factor activity. In contrast, protein tyrosine kinase inhibitors (genistein, lavendustin A) had no inhibitory effect on LPS-induced endothelial cell tissue factor expression. Our results collectively suggest that activation of PKC is an important step in stimulation of endothelial cells by LPS, and that LPS and phorbol esters may synergize to produce an enhanced stimulatory effect. Our results also suggest participation of cAMP in controlling LPS-mediated stimulation of endothelial cells, but fail to demonstrate a role for protein tyrosine kinase activity.