Differential inhibition of polymorphonuclear leukocyte recruitment in vivo by dextran sulphate and fucoidan

High Cytokine Levels in Tonsillitis Secretions Regardless of Presence of Beta-Hemolytic Streptococci

Acute pharyngotonsillitis denotes tonsillar inflammation caused by bacteria or viruses. Here, we investigated if beta-hemolytic streptococci (β-HS) tonsillitis would differ in inflammatory mediator response from tonsillitis of other causes. Tonsillar secretions were obtained from 36 acute pharyngotonsillitis patients and 16 controls. Bacteria were cultured quantitatively and 18 different viruses were quantified by real-time polymerase chain reaction. Cytokine and prostaglandin E2 (PGE2) levels were determined by enzyme-linked immunosorbent assays. Almost half of the patients' tonsillar secretions yielded high counts of β-HS, and most samples contained viruses, irrespective of whether β-HS were present or not. The Epstein-Barr virus (EBV) was the most common virus (patients 62% and controls 13%). Compared to controls, patients' secretions had higher levels of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF), and PGE2, while few samples contained IL-12, IL-10, or interferon-gamma (IFN-γ). The presence of β-HS in tonsillitis secretions could not be distinguished by any of the measured mediators, while the presence of EBV DNA tended to be associated with enhanced levels of IL-1β and IL-8. The results suggest a common inflammatory response in acute pharyngotonsillitis, regardless of causative agent. The suggested correlation between intense inflammation and the presence of EBV DNA in tonsillitis secretions may be due to reactivation of the virus and/or the EBV-containing B cells.

The Inhibitory Effects of Fucoidans from Laminaria japonica on Oxidation of Human Low-Density Lipoproteins

Five Fucoidan fractions from Laminaria japonica with different sulfate content and molecular weight were obtained by anion-exchange chromatography and mild acid hydrolysis. Their antioxidant effects on azo radicals AAPH- and AMVN -induced oxidation of human low-density lipoprotein (LDL) were evaluated by monitoring cholesteryl ester hydroperoxides (CHE-OOH) formation kinetics by HPLC analysis. Two antioxidants probucol and Vc were used as comparison. Fucoidan F-C with low molecular weight 2,000-8,000 and sulfate content 24.3% had much stronger protective antioxidant effects than other four Fucoidan fractions on both hydrophilic radical AAPH and lipophilic radical AMVN induced LDL oxidation. In AMVN induced LDL oxidation system, the other four Fucoidan fractions with molecular weight of 200,000 and 20,000 were able to modify the kinetics of LDL oxidation with the similar efficiency. However, the highly sulfated Fucoidan fraction L-B with molecular weight 20,000 was completely ineffective in protecting LDL from AAPH induced oxidation, whilst it effectively suppressed the oxidation of LDL induced by AMVN. The different protective antioxidant effects of Fucoidans on AAPH and AMVN induced LDL oxidation were due to their various structures and properties, and their capacities to interact with the different sites Fucoidans reacted on LDL.

Fucoidan a sulfated polysaccharide from brown algae is a potent modulator of connective tissue proteolysis

Fucoidans are sulfated fucosylated polymers from brown algae cell wall that exhibit some heparin/heparan sulfate properties. We previously demonstrated that these polysaccharides were able in vitro to stimulate dermal fibroblast proliferation and extracellular matrix deposition. Here, we investigated the action of a 16kDa fucoidan fraction on parameters involved in connective tissue breakdown. This fucoidan is able to inhibit gelatinase A secretion and stromelysin 1 induction by interleukin-1beta on dermal fibroblasts in culture. Furthermore, we observed that fucoidan increases the rate of association of MMPs with their specific inhibitors namely TIMPs. Using tissue sections of human skin in ex vivo experiments, we evidenced that this polysaccharide was able to minimize human leukocyte elastase activity resulting in the protection of human skin elastic fiber network against the enzymatic proteolysis due to this serine proteinase. These results suggested that fucoidan could be used for treating some inflammatory pathologies in which uncontrolled extracellular matrix degradation takes place.

Heparin-like polymers modulate proinflammatory cytokine production by lipopolysaccharide-stimulated human monocytes

The search for heparin-like materials remains an intensive field of research. In this context, we studied the immunomodulatory properties of semisynthetic dextran derivatives and naturally occurring sulfated polysaccharides present in brown seaweed (fucans). In this study, we investigated the functional potencies of fucan and dextran derivatives by analyzing their effects on the release of proinflammatory cytokines by resting or lipopolysaccharide (LPS)-stimulated human monocytes and their interactions on monocyte surfaces. The results showed that fucan, dextran derivatives, and heparin differentially (1) triggered interleukin-1alpha, tumor necrosis factor alpha, interleukin-6, and interleukin-8 production by monocytes in a dose-dependent manner, (2) modulated cytokine production by LPS-stimulated monocytes, and (3) specifically inhibited the binding of biotinylated LPS to monocyte membranes. Taken together, these data indicated that fucan and dextran derivatives displayed interesting immunomodulatory effects on human blood cells that could be relevant as new drugs or biomaterial coatings. Indeed, such polysaccharides, by regulating monocyte activation, could contribute to the improved biocompatibility of implants.

Role of polymorphonuclear leukocytes in collar-induced intimal thickening in the rabbit carotid artery

In this study, the involvement of polymorphonuclear leukocytes (PMNs) in the development of intimal thickening was investigated. A fibromuscular intima was induced by placing a silicone collar around the rabbit carotid artery for 3 days or 2 weeks; the contralateral artery was sham operated. Rabbits received placebo treatments (groups 1 and 3), granulocyte-colony stimulating factor (group 2; G-CSF, 20 microg x kg(-1) x d(-1), delivered by subcutaneous osmotic pumps), or an anti-CD18 monoclonal antibody (group 4; 1.5 mg/kg i.v.). The G-CSF treatment raised the peripheral PMN count 5- to 12-fold but had no effect on intimal thickening on day 3, 12, or 14. A single injection of anti-CD18 prevented PMN extravasation 6 hours after collar implantation without influencing intimal hyperplasia on day 14. Repeated daily administration of anti-CD18 strongly bound to CD18 on peripheral PMNs and inhibited both PMN-dependent plasma extravasation in the skin and accumulation of CD14-immunoreactive leukocytes in the intima and media. However, anti-CD18 did not suppress early intimal thickening or accumulation of alpha-smooth muscle actin-immunoreactive cells by day 3. It thus appears that the PMN influx in the intima and media evoked by the perivascular collar is of little functional relevance to the subsequent smooth muscle cell migration and intimal thickening in this model.

Histamine-induced biphasic macromolecular leakage in the microcirculation of the conscious hamster: evidence for a delayed nitric oxide-dependent leakage

1. Late effects (up to 3 h) of intravenously-injected histamine on FITC-dextran extravasation were investigated in the conscious hamster, by use of computer-assisted image analysis of fluorescence distribution in a microscopic window of dorsal skin fold preparations. This analysis allowed measurement of local (skin) and general (all organs) extravasations caused by a bolus injection of histamine (1 mg kg(-1), i.v.) 2. Histamine doses higher than 0.01 mg kg(-1) caused biphasic local and general extravasations. Initial phases developed fully within 15 min (for local) and 60 min (for general) and were followed by late phases beginning 90 min after histamine injection. Although the initial and late phases of histamine-induced extravasations had differential apparent reactivities to the autacoid, all the effects of histamine on the microcirculation (1 mg kg[-1]) were inhibited by pyrilamine (1 mg kg(-1), i.v.) but not by cimetidine (1 mg kg(-1), i.v.). 3. Pretreatment with N(G)-monomethyl-L-arginine (L-NMMA, 30 mg kg(-1), i.v.) or N(G)-nitro-L-arginine methyl ester (L-NAME, 100 mg kg(-1), i.v.) did not affect the initial phases but did prevent the late phases of local and general extravasations triggered by 1 mg kg(-1) histamine. The inhibitory effects of L-NAME were reversed by L-arginine (30 mg kg[-1]) but not by D-arginine (30 mg kg[-1]) according to the enantioselectivity of nitric oxide synthase (NOS). A late NO-mediated venular dilatation occurred in response to plasma histamine. 4. A low dose of aminoguanidine (1 mg kg(-1), i.v.), a selective inhibitor of the inducible isoform of NOS (iNOS), mimicked the inhibitory effects of L-NAME on the late phases of histamine-induced macromolecular extravasations and venular dilatation. 5. Pretreatment with dexamethasone (1 mg kg(-1), i.v.) prevented both the initial and late phases of histamine-induced extravasations. Fucoidan (1 or 25 mg kg(-1), i.v.) prevented the late phases without affecting initial phases, consistent with a role for leukocytes adhesion in the development of the late NO-mediated effects of histamine. 6. We conclude that intravenous injection of histamine triggers a biphasic inflammatory cascade via initial activation of H1 receptors which induces a late NO-mediated PMN-dependent extravasation process.