Regulation of interleukin-8 binding and function by heparin and alpha2-macroglobulin

Glycosaminoglycans and fucoidan have a protective effect on experimental glomerulonephritis

Background: The glomerular endothelial glycocalyx is degraded during inflammation. The glycocalyx plays a pivotal role in endothelial function and is involved in many processes including binding of chemokines and cytokines, leukocyte trafficking, and preventing proteinuria. HS-based therapeutics are a promising novel class of anti-inflammatory drugs to restore a compromised endothelial glycocalyx under inflammatory conditions. Recently, we demonstrated that treatment with HS extracted from unstimulated glomerular endothelial glycocalyx (unstimulated HS_glx) reduced albuminuria during anti-GBM induced glomerulonephritis. Since endothelial HS domains are distinct in unstimulated versus inflammatory conditions, we hypothesized that 1) unstimulated HS_glx, 2) LPS-stimulated HS_glx, 3) the HS-mimetic fucoidan and 4) the glycosaminoglycan preparation sulodexide, which is a mixture of low molecular weight heparin and dermatan sulfate, might have different beneficial effects in experimental glomerulonephritis. Methods: The effect of unstimulated HS_glx, LPS HS_glx, Laminaria japonica fucoidan, or sulodexide on experimental glomerulonephritis was tested in LPS-induced glomerulonephritis in mice. Analyses included urinary albumin creatinine measurement, cytokine expression in plasma and renal cortex, and renal influx of immune cells determined by flow cytometry and immunofluorescence staining. Furthermore, the observed in vivo effects were evaluated in cultured glomerular endothelial cells and peripheral blood mononuclear cells by measuring cytokine and ICAM-1 expression levels. The ability of the compounds to inhibit heparanase activity was assessed in a heparanase activity assay. Results: Treatment of mice with LPS HS_glx or sulodexide near-significantly attenuated LPS-induced proteinuria. All treatments reduced plasma MCP-1 levels, whereas only fucoidan reduced IL-6 and IL-10 plasma levels. Moreover, all treatments reversed cortical ICAM-1 mRNA expression and both fucoidan and sulodexide reversed cortical IL-6 and nephrin mRNA expression. Sulodexide decreased renal influx of CD45⁺ immune cells whereas renal influx of macrophages and granulocytes remained unaltered for all treatments. Although all compounds inhibited HPSE activity, fucoidan and sulodexide were the most potent inhibitors. Notably, fucoidan and sulodexide decreased LPS-induced mRNA expression of ICAM-1 and IL-6 by cultured glomerular endothelial cells. Conclusion: Our data show a potentially protective effect of glycosaminoglycans and fucoidan in experimental glomerulonephritis. Future research should be aimed at the further identification of defined HS structures that have therapeutic potential in the treatment of glomerular diseases.

Anticoagulation in hospitalized patients with COVID-19

Coronavirus disease-19 (COVID-19) includes a thromboinflammatory syndrome that may manifest with microvascular and macrovascular thrombosis. Patients with COVID-19 have a higher incidence of venous thromboembolism than other hospitalized patients. Three randomized control trials suggesting benefit of therapeutic heparin in hospitalized noncritically ill patients with COVID-19 have led to conditional guideline recommendations for this treatment. By contrast, prophylactic-dose heparin is recommended for critically ill patients. Unprecedented collaboration and rapidly funded research have improved care of hospitalized patients with COVID-19.

Hypercoagulability of COVID-19 and Neurological Complications: A Review

The SARS-CoV-2 virus, which causes Coronavirus disease 2019 (COVID-19), has resulted in millions of worldwide deaths. When the SARS-CoV-2 virus emerged from Wuhan, China in December 2019, reports of patients with COVID-19 revealed that hospitalized patients had acute changes in mental status, cognition, and encephalopathy. Neurologic complications can be a consequence from overall severity of the systemic infection, direct viral invasion of the SARS-CoV-2 virus in the central nervous system, and possible immune mediated mechanisms. We will examine the landscape regarding this topic in this review in addition to current understandings of COVID-19 and hemostasis, treatment, and prevention, as well as vaccination.

Beneficial non-anticoagulant mechanisms underlying heparin treatment of COVID-19 patients

Coronavirus disease-2019 (COVID-19) is associated with severe inflammation in mainly the lung, and kidney. Reports suggest a beneficial effect of the use of heparin/low molecular weight heparin (LMWH) on mortality in COVID-19. In part, this beneficial effect could be explained by the anticoagulant properties of heparin/LMWH. Here, we summarise potential beneficial, non-anticoagulant mechanisms underlying treatment of COVID-19 patients with heparin/LMWH, which include: (i) Inhibition of heparanase activity, responsible for endothelial leakage; (ii) Neutralisation of chemokines, and cytokines; (iii) Interference with leukocyte trafficking; (iv) Reducing viral cellular entry, and (v) Neutralisation of extracellular cytotoxic histones. Considering the multiple inflammatory and pathogenic mechanisms targeted by heparin/LMWH, it is warranted to conduct clinical studies that evaluate therapeutic doses of heparin/LMWH in COVID-19 patients. In addition, identification of specific heparin-derived sequences that are functional in targeting non-anticoagulant mechanisms may have even higher therapeutic potential for COVID-19 patients, and patients suffering from other inflammatory diseases.

Targeting Chemokine-Glycosaminoglycan Interactions to Inhibit Inflammation

Leukocyte migration into tissues depends on the activity of chemokines that form concentration gradients to guide leukocytes to a specific site. Interaction of chemokines with their specific G protein-coupled receptors (GPCRs) on leukocytes induces leukocyte adhesion to the endothelial cells, followed by extravasation of the leukocytes and subsequent directed migration along the chemotactic gradient. Interaction of chemokines with glycosaminoglycans (GAGs) is crucial for extravasation in vivo. Chemokines need to interact with GAGs on endothelial cells and in the extracellular matrix in tissues in order to be presented on the endothelium of blood vessels and to create a concentration gradient. Local chemokine retention establishes a chemokine gradient and prevents diffusion and degradation. During the last two decades, research aiming at reducing chemokine activity mainly focused on the identification of inhibitors of the interaction between chemokines and their cognate GPCRs. This approach only resulted in limited success. However, an alternative strategy, targeting chemokine-GAG interactions, may be a promising approach to inhibit chemokine activity and inflammation. On this line, proteins derived from viruses and parasites that bind chemokines or GAGs may have the potential to interfere with chemokine-GAG interactions. Alternatively, chemokine mimetics, including truncated chemokines and mutant chemokines, can compete with chemokines for binding to GAGs. Such truncated or mutated chemokines are characterized by a strong binding affinity for GAGs and abrogated binding to their chemokine receptors. Finally, Spiegelmers that mask the GAG-binding site on chemokines, thereby preventing chemokine-GAG interactions, were developed. In this review, the importance of GAGs for chemokine activity in vivo and strategies that could be employed to target chemokine-GAG interactions will be discussed in the context of inflammation.

Modulation of Interleukin-12 activity in the presence of heparin

Glycosaminoglycans (GAGs), especially heparin and heparan sulfate (HS), modulate the functions of numerous cytokines. The aims of this multidisciplinary research were to characterize heparin binding to interleukin-12 (IL-12) and determine the mechanism(s) by which heparin influences IL-12 bioactivity. Heparin and HS were found to bind human IL-12 (hIL-12) with low micromolar affinity and increase hIL-12 bioactivity by more than 6-fold. Conversely, other GAGs did not demonstrate significant binding, nor did their addition affect hIL-12 bioactivity. Biophysical studies demonstrated that heparin induced only minor conformational changes while size-exclusion chromatography and small angle X-ray scattering studies indicated that heparin induced dimerization of hIL-12. Heparin modestly protected hIL-12 from proteolytic degradation, however, this was not a likely mechanism for increased cytokine activity in vitro. Flow cytometry studies revealed that heparin increased the amount of hIL-12 bound to cell surfaces. Heparin also facilitated hIL-12 binding and signaling in cells in which both hIL-12 receptor subunits were functionally deleted. Results of this study demonstrate a new role for heparin in modulating the biological activity of IL-12.

Glycosaminoglycan-based hydrogels capture inflammatory chemokines and rescue defective wound healing in mice

Excessive production of inflammatory chemokines can cause chronic inflammation and thus impair cutaneous wound healing. Capturing chemokine signals using wound dressing materials may offer powerful new treatment modalities for chronic wounds. Here, a modular hydrogel based on end-functionalized star-shaped polyethylene glycol (starPEG) and derivatives of the glycosaminoglycan (GAG) heparin was customized for maximal chemokine sequestration. The material is shown to effectively scavenge the inflammatory chemokines MCP-1 (monocyte chemoattractant protein-1), IL-8 (interleukin-8), and MIP-1α (macrophage inflammatory protein-1α) and MIP-1β (macrophage inflammatory protein-1β) in wound fluids from patients suffering from chronic venous leg ulcers and to reduce the migratory activity of human monocytes and polymorphonuclear neutrophils. In an in vivo model of delayed wound healing (db/db mice), starPEG-GAG hydrogels outperformed the standard-of-care product Promogran with respect to reduction of inflammation, as well as increased granulation tissue formation, vascularization, and wound closure.

Inhaled Heparin: Therapeutic Efficacy and Recent Formulations

Heparin is well known for its anticoagulant and anti-inflammatory properties. Inhaled heparin regimens are increasingly being used to manage lung disease. It has been used to treat cystic fibrosis, thromboembolism, and pulmonary fibrosis, as well as bronchial asthma and asthma-induced airway hypersensitivity. Several preclinical studies attained some useful effects of heparin-administered, parenterally and through inhalation, treatment of lung disease. Besides, recent clinical trials suggest that inhaled heparin for lung diseases is beneficial and safe, but such data remain to be limited. In 2005, the orphan designation was granted by the European Commission for heparin sodium (inhalation use) for the treatment of cystic fibrosis. The positive results of heparin in the pulmonary route necessitate a focus on the preparation and evaluation of heparin in advanced drug delivery systems, namely nano/microparticles and liposomes. Through this pulmonary delivery, heparin is protected from enzymatic degradation within the airway. Heparin is thus passively targeted into the lungs, and long-lasting localized treatment is achieved. On the other hand, these systems have encountered several problems as follows: (1) polymers, such as poly-L-lactide-glycolic acid, poly (lactic acid), and chitosan, used to prepare heparin-loaded microparticle/nanoparticle (MP/NP) systems have not been granted approval for lung application by the FDA and (2) liposomal and NP formulation stability is the main problem of formulation design. We propose that additional in vitro and in vivo research is necessary to assess the clinical applicability of this treatment strategy. The present article discusses heparin treatments for lung diseases and the use of heparin and/or heparin-loaded drugs in advanced delivery systems through the pulmonary route.

Interference with glycosaminoglycan-chemokine interactions with a probe to alter leukocyte recruitment and inflammation in vivo

In vivo leukocyte recruitment is not fully understood and may result from interactions of chemokines with glycosaminoglycans/GAGs. We previously showed that chlorite-oxidized oxyamylose/COAM binds the neutrophil chemokine GCP-2/CXCL6. Here, mouse chemokine binding by COAM was studied systematically and binding affinities of chemokines to COAM versus GAGs were compared. COAM and heparan sulphate bound the mouse CXC chemokines KC/CXCL1, MIP-2/CXCL2, IP-10/CXCL10 and I-TAC/CXCL11 and the CC chemokine RANTES/CCL5 with affinities in the nanomolar range, whereas no binding interactions were observed for mouse MCP-1/CCL2, MIP-1α/CCL3 and MIP-1β/CCL4. The affinities of COAM-interacting chemokines were similar to or higher than those observed for heparan sulphate. Although COAM did not display chemotactic activity by itself, its co-administration with mouse GCP-2/CXCL6 and MIP-2/CXCL2 or its binding of endogenous chemokines resulted in fast and cooperative peritoneal neutrophil recruitment and in extravasation into the cremaster muscle invivo. These local GAG mimetic features by COAM within tissues superseded systemic effects and were sufficient and applicable to reduce LPS-induced liver-specific neutrophil recruitment and activation. COAM mimics glycosaminoglycans and is a nontoxic probe for the study of leukocyte recruitment and inflammation invivo.

Functional aspects of the interaction between interleukin-8 and sulfated glycosaminoglycans

During the immune response, the cytokine interleukin 8 (IL-8, CXCL8) functions as a strong chemoattractant for polymorphonuclear leukocytes helping to direct these cells to infected/injured sites. This review focuses on the interaction of IL-8 with sulfated glycosaminoglycans expressed on cell surfaces and the extracellular matrix. This interaction contributes to the recruitment of polymorphonuclear cells from blood, penetration of these cells through the vessel wall, and their directed migration to inflammatory sites. Regulatory aspects of the interplay between IL-8 and heparan sulfate, the most abundant glycosaminoglycan, are highlighted. In this field, the large natural heterogeneity of glycosaminoglycans represents a great challenge that impedes the modeling of IL-8 functions. The interaction of IL-8 with newly developed artificial sulfated hyaluronan derivatives is also considered as these artificial substrates are an important tool for development of new materials in regenerative medicine.

Non-anticoagulant derivatives of heparin for the management of asthma: distant dream or close reality?

INTRODUCTION

Approximately 300 million people worldwide are currently affected by asthma. Improvements in the understanding of the mechanisms involved in such inflammatory airway disorders has led to the recognition of new therapeutic approaches. Heparin, a widely used anticoagulant, has been shown to be beneficial in the management of asthma. It belongs to the family of highly sulphated polysaccharides referred to as glycosaminoglycans, containing a heterogeneous mixture of both anticoagulant and non-anticoagulant polysaccharides. Experimental findings have suggested that heparin has potential anti-asthmatic properties owing to the ability of its non-anticoagulant oligosaccharides to bind and modulate the activity of a wide range of biological molecules involved in the inflammatory process.

AREAS COVERED

This review focuses on the potential mechanisms of action and clinical application of heparin as an anti-inflammatory agent for the management of asthma.

EXPERT OPINION

Heparin may play a significant role in the management of asthma. However, these properties are often hindered by the presence of anticoagulant oligosaccharides, which possess a significant risk of bleeding. Therefore, its therapeutic potential must be explored using well-designed clinical studies that focus on identifying and isolating the anti-inflammatory oligosaccharides of heparin and further elucidating the structure and mechanisms of actions of these non-anticoagulant oligosaccharides.

Quantitative proteomics reveals altered expression of extracellular matrix related proteins of human primary dermal fibroblasts in response to sulfated hyaluronan and collagen applied as artificial extracellular matrix

Fibroblasts are the main matrix producing cells of the dermis and are also strongly regulated by their matrix environment which can be used to improve and guide skin wound healing processes. Here, we systematically investigated the molecular effects on primary dermal fibroblasts in response to high-sulfated hyaluronan [HA] (hsHA) by quantitative proteomics. The comparison of non- and high-sulfated HA revealed regulation of 84 of more than 1,200 quantified proteins. Based on gene enrichment we found that sulfation of HA alters extracellular matrix remodeling. The collagen degrading enzymes cathepsin K, matrix metalloproteinases-2 and -14 were found to be down-regulated on hsHA. Additionally protein expression of thrombospondin-1, decorin, collagen types I and XII were reduced, whereas the expression of trophoblast glycoprotein and collagen type VI were slightly increased. This study demonstrates that global proteomics provides a valuable tool for revealing proteins involved in molecular effects of growth substrates for further material optimization.

Glycosaminoglycan and chemokine/growth factor interactions

Heparin and glycosaminoglycans (GAGs) related structurally to heparin, notably heparan sulphate, bind to most, if not all, chemokines and many growth factors. The chemokine and growth factor interactions with GAGs localise the peptide mediators to specific sites in tissues and influence their stability and function. This chapter discusses the nature of these interactions and the effect on the function of a number of chemokines (PF-4, interleukin-8, RANTES and SDF-1) and growth factors (FGF, HGF, VEGF) in normal physiology and the disease setting. Novel therapeutic interventions that target chemokine and growth factor interactions with GAGs are also discussed.

Interleukin-8 and acute kidney injury following cardiopulmonary bypass: a prospective cohort study

BACKGROUND

Cardiopulmonary bypass (CPB) elicits an inflammatory response mediated partly by neutrophils, which are activated and recruited by interleukin-8 (IL-8). We hypothesized that acute kidney injury (AKI) following CPB might be mediated by IL-8 and examined the association of perioperative plasma IL-8 levels with AKI in a prospective cohort.

METHODS

Plasma IL-8 was measured before, and 2, 24 and 48 h following CPB. Two AKI definitions, a serum creatinine increase of > or = 0.3 mg/dl or 50% (AKI Network [AKIN] stage-1) or > or = 50% alone (AKI-50%), within the first 72 h, were used. Area under the receiver operator characteristic curves (AUCs) were generated and multivariable logistic regression analyses performed.

RESULTS

A total of 143 patients were enrolled. The baseline mean serum creatinine was 1.1 mg/ dl (SD = 0.3), the CPB perfusion time was 112 min (SD = 43). Twenty-nine percent of the patients developed AKIN stage-1 and 13% AKI-50%. The plasma IL-8 level 2 h after CPB was higher in AKIN stage-1 (p = 0.03) and AKI-50% (p < 0.01), and predicted AKIN stage-1 (AUC = 0.62; p = 0.02) and AKI-50% (AUC = 0.72; p < 0.01). On multivariable analysis, the 2-hour plasma IL-8 level was associated with 1.36- and 1.59-fold higher odds for AKIN stage-1 and AKI-50%, respectively (p = 0.05).

CONCLUSION

Plasma IL-8 predicts the development of AKI following CPB, supporting a potential involvement for this chemokine in the pathogenesis of AKI.

Unfractionated heparin reduces the elasticity of sputum from patients with cystic fibrosis

Mucus obstruction of the airway in patients with cystic fibrosis (CF) reduces lung function, invites infection, and limits delivery of inhaled drugs including gene therapy vectors to target cells. Not all patients respond to presently available mucolytics, and new approaches are needed. Our objectives were to investigate the in vitro effects of unfractionated heparin (UFH) on the morphology and rheology of sputum and the effect of UFH on diffusion of 200-nm nanospheres through sputum from adult CF patients. Confocal laser scanning microscopy was used to image fluorescently stained actin and DNA components of CF sputum, and atomic force microscopy was used to image isolated DNA networks. The viscoelasticity of CF sputum was measured using dynamic oscillatory rheometry. Nanosphere diffusion was measured through CF sputum using a Boyden chamber-based assay. Actin-DNA bundles in CF sputum were disaggregated by UFH at concentrations of 0.1–10 mg/ml, and UFH enhanced the endonuclease activity in sputum from patients on dornase alfa therapy. UFH significantly reduced the elasticity and yield stress, but not the viscosity, of CF sputum from patients not receiving dornase alfa therapy. Heparin dose-dependently significantly increased the diffusion of nanospheres through CF sputum from patients not on dornase alfa therapy from 10.5 ± 2.5% at baseline to 36.9 ± 4.4% at 10 mg/ml but was more potent, with maximal effect at 0.1 mg/ml, in patients who were on dornase alfa therapy. Thus the mucoactive properties of UFH indicate its potential as a new therapeutic approach in patients with cystic fibrosis.

The effects of high-dose heparin on inflammatory and coagulation parameters following cardiopulmonary bypass

Systemic inflammation and the activation of the coagulation system following cardiopulmonary bypass (CPB) may contribute to postoperative complications. In vitro studies have demonstrated that heparin possesses anti-inflammatory properties. To ascertain the relative benefits of high versus low heparin doses, we studied the impact of varying heparin doses on the inflammatory response and coagulation system during and following CPB. Forty patients scheduled for elective coronary artery bypass surgery requiring CPB were randomized to either a low dose (300 U/kg) (Group L) or a high dose of unfractionated heparin (600 U/kg) (Group H). To evaluate the inflammatory response, proinflammatory cytokines [tumor necrosis factor-alpha and interleukin-6 (IL-6)] were measured at four different times: before CPB (T0), 30 min after the institution of CPB (T1), 30 min after cross-clamp release (T2), and 4 h after the end of CPB (T3). Thrombin-antithrombin complex, platelet factor 4 and anti-activated factor X heparin concentrations were also measured. Patients in Group H received greater heparin (44.934 U versus 27.741 U, P<0.001) and protamine (P=0.003) doses. Postoperative blood loss and blood products transfusions were not significantly different in the groups. At T1, mean heparin plasma concentration was higher in Group H (P<0.001). IL-6 was significantly lower in Group H compared with Group L (P=0.01) only at T1. Using a mixed-effects statistical model, tumor necrosis factor-alpha and IL-6 levels were comparable regardless of the heparin dose. Thrombin-antithrombin complex levels were lower in Group H (P=0.04) and platelet factor 4 levels were significantly lower in Group H at T2 (P=0.04). Higher heparin doses were associated with higher heparin concentrations during CPB. A high heparin dose achieved a better preservation of the coagulation system with less thrombin formation and platelet activation. The heparin dose had small influence on proinflammatory cytokines release.

Additional clinical benefit of enoxaparin in COPD patients receiving salmeterol and fluticasone propionate in combination

It is now well recognised that heparin possesses numerous anti-inflammatory properties in addition to its anticoagulant properties. Thus, the aim of this study was to investigate the effects of the low molecular weight heparin, enoxaparin (ENX), as an add-on therapy for a period of 12 weeks, to inhaled salmeterol/fluticasone propionate (SLM/FP) combination in patients with stable chronic obstructive pulmonary disease (COPD). Forty-six patients were randomised to receive 12 weeks of treatment in one of two treatment groups: (1) fixed combination of SLM 50 microg and FP 500 microg Diskus, one inhalation twice daily; or (2) as group 1 plus 20 mg ENX administered subcutaneously once daily for 12 weeks. Patients attended the clinic before and after 4, 8 and 12 weeks of treatment for evaluations of lung function, blood gas tensions, dyspnoea and supplemental salbutamol use. Thirty-six patients completed the 12-week treatment period, 20 from group 1 and 16 from group 2. A significant increase in forced expiratory volume in 1 s (FEV1) over baseline was observed after 12 weeks of treatment in group 1 (0.145 L, 95% CI: 0.994-1.406, p<0.01), whilst significant increases in FEV1 over baseline were observed in group 2 after 4, 8 and 12 weeks of treatment with a maximum increase at 12 weeks of 0.244 L (95% CI: 1.175-1.596, p<0.01). Both treatment groups experienced similar improvements in blood gas tensions, dyspnoea and supplemental salbutamol use. Our results suggest that addition of ENX to conventional therapy of COPD may provide additional clinical benefit and must be further investigated as a treatment for COPD.

The CX3C-Chemokine Fractalkine (CX3CL1) is Detectable in Serum of Patients Affected by the Inflammatory Diseases Allergic Rhinitis and/or Asthma

Fractalkine (FKN) is a chemokine able to mediate the initial capture, firm adhesion, and activation of circulating leukocytes. Many tissues express FKN mRNA and FKN expression is increased during inflammatory conditions. To assess a possible involvement in allergic airway disease, we detected serum levels of FKN in a group of patients affected by allergic rhinitis and/or asthma and found high serum levels of FKN in all patients and in only 26% of healthy donors at lower concentrations. The present results underscore the potential role that this chemokine may play in the pathogenesis of respiratory allergic diseases.

Cytokines and inflammatory mediators in cystic fibrosis

Airway disease in cystic fibrosis (CF) is characterised by a continuous cycle of chronic infection and inflammation dominated by a neutrophilic infiltrate. This inflammation is characterised by an increased production of pro-inflammatory cytokines in the lung. The relationship between the abnormal CFTR gene product and the development of inflammation and progression of lung disease in CF is not fully understood. This review article studied the mechanisms of pulmonary inflammation in CF, the profiles of cytokines and inflammatory mediators in the lung in CF, the mechanisms that predispose to chronic Pseudomonas aeruginosa infection, cytokine involvement in diseases other than CF and reviewed current therapeutic strategies for CF. Imbalances of cytokine secretion are now better understood due to recent advances in understanding CF at a molecular level and it is increasingly thought that the normal inflammatory process is deranged in CF early in the course of the disease and may occur in the absence of detectable infection. However, the relationship between this unbalanced cytokine production, the mutations in CFTR and its actual consequence for pathogenesis need further investigation.

The impact of heparin compounds on cellular inflammatory responses: a construct for future investigation and pharmaceutical development

Atherosclerotic disease is recognized as a chronic inflammatory disorder with intermittent and widely variable phases of cellular proliferation and heightened thrombotic activity. The multi-tiered links between inflammation, atherogenesis and thrombogenesis provide a unique opportunity for research and development of pharmaceuticals which target one or more critical pathobiologic steps (Fig. 1). The purpose of the following review on heparin compounds is to comprehensively examine the multi-cellular, pleuripotential effects of a commonly used anticoagulant drug in the context of normal and disease-altered vascular responses and illustrate possible constructs for avenues of subsequent investigation in the field of atherothrombosis. The overview is divided into five integrated parts; antiinflammatory properties of the normal vessel wall, the relationship between glycosaminoglycans and inflammation, heparin-mediated effects on cellular inflammatory responses, association between molecular weight and antiinflammatory capabilities, and oral heparin compounds for achieving prolonged cell-based inhibition.

Free secretory component from cystic fibrosis sputa displays the cystic fibrosis glycosylation phenotype

Secretory IgA contributes to humoral defense mechanisms against pathogens targeting mucosal surfaces, and secretory component (SC) fulfills multiple roles in this defense. The aims of this study were to quantify total SC and to analyze the form of free SC in sputa from normal subjects, subjects with asthma, and subjects with cystic fibrosis (CF). Significantly higher levels of SC were detected in CF compared with both other groups. Gel filtration chromatography revealed that SC in CF was relatively degraded. Free SC normally binds interleukin (IL)-8 and inhibits its function. However, in CF sputa, IL-8 binding to intact SC was reduced. Analysis of the total carbohydrate content of free SC signified overglycosylation in CF compared with normal subjects and subjects with asthma. Monosaccharide composition analysis of free SC from CF subjects revealed overfucosylation and undersialylation, in agreement with the reported CF glycosylation phenotype. SC binding to IL-8 did not interfere with the binding of IL-8 to heparin, indicating distinct binding sites on IL-8 for negative regulation of function by SC and heparin. We suggest that defective structure and function of SC contribute to the characteristic sustained inflammatory response in the CF airways.

Plasminogen activator inhibitor-1 supports IL-8-mediated neutrophil transendothelial migration by inhibition of the constitutive shedding of endothelial IL-8/heparan sulfate/syndecan-1 complexes

The endothelium is the primary barrier to leukocyte recruitment at sites of inflammation. Neutrophil recruitment is directed by transendothelial gradients of IL-8 that, in vivo, are bound to the endothelial cell surface. We have investigated the identity and function of the binding site(s) in an in vitro model of neutrophil transendothelial migration. In endothelial culture supernatants, IL-8 was detected in a trimolecular complex with heparan sulfate and syndecan-1. Constitutive shedding of IL-8 in this form was increased in the presence of a neutralizing Ab to plasminogen activator inhibitor-1 (PAI-1), indicating a role for endothelial plasminogen activator in the shedding of IL-8. Increased shedding of IL-8/heparan sulfate/syndecan-1 complexes was accompanied by inhibition of neutrophil transendothelial migration, and aprotinin, a potent plasmin inhibitor, reversed this inhibition. Platelets, added as an exogenous source of PAI-1, had no effect on shedding of the complexes or neutrophil migration. Our results indicate that IL-8 is immobilized on the endothelial cell surface through binding to syndecan-1 ectodomains, and that plasmin, generated by endothelial plasminogen activator, induces the shedding of this form of IL-8. PAI-1 appears to stabilize the chemoattractant form of IL-8 at the cell surface and may represent a therapeutic target for novel anti-inflammatory strategies.

Effects of heparin and related molecules upon neutrophil aggregation and elastase release in vitro

1 Neutrophil-derived elastase is an enzyme implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Heparin inhibits the enzymatic activity of elastase and here we provide evidence for the first time that heparin can inhibit the release of elastase from human neutrophils. 2 Unfractionated and low molecular weight heparins (UH and LMWH, 0.01-1000 U ml(-1)) and corresponding concentrations (0.06-6000 micro g ml(-1)) of nonanticoagulant O-desulphated heparin (ODH), dextran sulphate (DS) and nonsulphated poly-L-glutamic acid (PGA) were compared for their effects on both elastase release from and aggregation of neutrophils. 3 UH, ODH and LMWH inhibited (P<0.05) the homotypic aggregation of neutrophils, in response to both N-formyl-methionyl-leucyl-phenylalanine (fMLP, 10(-6) M) and platelet-activating factor (PAF, 10(-6) M), as well as elastase release in response to these stimuli, in the absence and presence of the priming agent tumour necrosis factor-alpha (TNF-alpha, 100 U ml(-1)). 4 DS inhibited elastase release under all the conditions of cellular activation tested (P<0.05) but had no effect on aggregation. PGA lacked efficacy in either assay, suggesting general sulphation to be important in both effects of heparin on neutrophil function and specific patterns of sulphation to be required for inhibition of aggregation. 5 Further investigation of the structural requirements for inhibition of elastase release confirmed the nonsulphated GAG hyaluronic acid and neutral dextran, respectively, to be without effect, whereas the IP(3) receptor antagonist 2-aminoethoxydiphenylborate (2-APB) mimicked the effects of heparin, itself an established IP(3) receptor antagonist, suggesting this to be a possible mechanism of action.

Heparin inhibits hyperventilation-induced late-phase hyperreactivity in dogs

Inhalation of heparin attenuates hyperventilation-induced bronchoconstriction in humans and dogs. The purpose of this study was to determine whether heparin inhibits the late-phase response to hyperventilation, which is characterized by increased peripheral airway resistance (RP), eicosanoid mediator production, neutrophilic/ eosinophilic inflammation, and airway hyperreactivity (AHR) at 5 h after dry air challenge (DAC). Fiberoptic bronchoscopy was used to record RP and airway reactivity (DeltaRP) to aerosol and intravenous histamine before and 5 h after DAC. Bronchoalveolar lavage fluid (BALF) cells and eicosanoid mediators were also measured approximately 5 h after DAC. DAC of vehicle-treated bronchi resulted in late-phase airway obstruction (approximately 120% increase over baseline RP), inflammation, increased BALF concentrations of leukotriene (LT) C(4), LTD(4), and LTE(4) and prostaglandin (PG)D(2), and AHR. Pretreatment with aerosolized heparin attenuated late-phase airway obstruction by approximately 50%, inhibited eosinophil infiltration, reduced BALF concentrations of LTC(4), LTD(4), and LTE(4) and PGD(2), and abolished AHR. We conclude that heparin inhibits hyperventilation-induced late-phase changes in peripheral airway function, and does so in part via the inhibition of eosinophil migration and eicosanoid mediator production and release.

IL-8 released constitutively by primary bronchial epithelial cells in culture forms an inactive complex with secretory component

The bronchial epithelium is a source of both alpha and beta chemokines and, uniquely, of secretory component (SC), the extracellular ligand-binding domain of the polymeric IgA receptor. Ig superfamily relatives of SC, such as IgG and alpha(2)-macroglobulin, bind IL-8. Therefore, we tested the hypothesis that SC binds IL-8, modifying its activity as a neutrophil chemoattractant. Primary bronchial epithelial cells were cultured under conditions to optimize SC synthesis. The chemokines IL-8, epithelial neutrophil-activating peptide-78, growth-related oncogene alpha, and RANTES were released constitutively by epithelial cells from both normal and asthmatic donors and detected in high m.w. complexes with SC. There were no qualitative differences in the production of SC-chemokine complexes by epithelial cells from normal or asthmatic donors, and in all cases this was the only form of chemokine detected. SC contains 15% N-linked carbohydrate, and complete deglycosylation with peptide N-glycosidase F abolished IL-8 binding. In micro-Boyden chamber assays, no IL-8-dependent neutrophil chemotactic responses to epithelial culture supernatants could be demonstrated. SC dose-dependently (IC(50) approximately 0.3 nM) inhibited the neutrophil chemotactic response to rIL-8 (10 nM) in micro-Boyden chamber assays and also inhibited IL-8-mediated neutrophil transendothelial migration. SC inhibited the binding of IL-8 to nonspecific binding sites on polycarbonate filters and endothelial cell monolayers, and therefore the formation of haptotactic gradients, without effects on IL-8 binding to specific receptors on neutrophils. The data indicate that in the airways IL-8 may be solubilized and inactivated by binding to SC.

Novel therapies in the treatment of ulcerative colitis

Ulcerative colitis is a chronic inflammatory disease of unknown cause. Its course is one of relapse and remission and requires therapy for both the induction and maintenance of remission. The progress in the fields of genetics and immunology has afforded important advances in our understanding of the inflammatory process. Traditional therapy with non-specific anti-inflammatories for ulcerative colitis remains our gold standard as newer targeted therapies have failed to provide any improved efficacy. This review examines the most recent compounds in development for the treatment of ulcerative colitis, including data from early clinical trials and the potential clinical impact of future entities.

Heparin therapy for ulcerative colitis? Effects and mechanisms

Despite intensive medical treatment with steroids and immunosuppressants, acute colitis is still associated with a colectomy rate of up to 15%. Following the observation that a patient with severe steroid-resistant colitis went into remission when treated with heparin for a deep vein thrombosis, there have been a number of reports on the use of heparin in acute ulcerative colitis. Although small and uncontrolled, these studies consistently demonstrate the beneficial effects of heparin, with surprisingly few side-effects in a disease characterized by mucosal haemorrhage. The mechanisms by which heparin may ameliorate ulcerative colitis remain unclear. A simple anticoagulant effect may be responsible, but similar effects are not seen with warfarin. As a result of their intense negative charge, the glycosaminoglycans that constitute heparin have diverse biological effects. These include potent anti-inflammatory actions, in vitro and in vivo, and the potentiation of the activity of the peptide growth factors necessary for mucosal regeneration and repair. This review summarizes the clinical reports on heparin treatment for ulcerative colitis and explores the mechanisms by which this novel form of treatment may exert its effects.

DNA and actin bind and inhibit interleukin-8 function in cystic fibrosis sputa: in vitro effects of mucolytics

Infection of the cystic fibrosis (CF) airways elicits an exaggerated, interleukin-8 (IL-8) mediated, neutrophil inflammatory response. Necrosing neutrophils release DNA and actin into the airways, increasing the viscoelasticity of airway secretions. Mucolytics aim to improve airway clearance by reducing this viscoelasticity. DNase I reduces the viscoelasticity of CF sputum, and a human recombinant form of this enzyme is widely administered to patients with CF. Gelsolin, which cleaves actin polymers, is also known to reduce CF sputum viscosity in vitro, and it has been proposed as a future mucolytic agent. We have shown that the anionic polymers DNA and actin bind and mask immunologic recognition of the basic peptide IL-8 and prevent this chemokine from binding to neutrophil receptors. Reduction of CF sputum viscosity by DNase I or gelsolin in vitro was demonstrated to increase the proportion of free IL-8 and the IL-8-dependent neutrophil chemotactic activity of sputum supernatants. We hypothesize that an electrostatic interaction between polymer and chemokine may limit the inflammatory potential of the latter, but that this interaction may be weakened by polymer cleavage. The potential risk of increased inflammation via this mechanism suggests a caveat should be attendant on treatment of patients with CF with these mucolytic agents.

Review article: potential therapeutic applications and mechanisms of action of heparin in inflammatory bowel disease

Unfractioned heparin was recently reported to be beneficial in the treatment of inflammatory bowel disease. The available uncontrolled data show that it may be effective in steroid-resistant ulcerative colitis with a percentage of complete clinical remission of over 70% after an average of 4-6 weeks of therapy. The administration of unfractioned heparin is not currently justified by the very limited available data. The worsening of rectal bleeding is infrequent in treated ulcerative colitis patients and only rarely does it require blood transfusion or a colectomy. Low molecular weight heparin was used in a single trial in patients with steroid-refractory ulcerative colitis, with results similar to those observed with unfractioned heparin. Since a prothrombotic state has been described in inflammatory bowel disease, and microvascular intestinal occlusion seems to play a role in the pathogenesis of inflammatory bowel disease, it is reasonable that part of the beneficial effects of unfractioned heparin in inflammatory bowel disease may result from its anticoagulant properties. However, beyond its well-known anticoagulant activity, unfractioned heparin also exhibits a broad spectrum of immunomodulating and anti-inflammatory properties, by inhibiting the recruitment of neutrophils and reducing pro-inflammatory cytokines. Moreover, it can restore the high-affinity receptor binding of basic fibroblast growth factor and this would aid healing of the ulcerated mucosa. In conclusion, unfractioned heparin may represent a safe therapeutic option for severe, steroid-resistant ulcerative colitis, although randomized, controlled trials are needed to confirm these data.

Heparin and heparan sulfate bind interleukin-10 and modulate its activity

Glycosaminoglycans (GAG) are a group of negatively charged molecules that have been shown to bind and directly regulate the bioactivity of growth factors and cytokines such as basic fibroblast growth factor, transforming growth factor-β, IL-7, and interferon-γ. The ability of GAG to interact with human IL-10 (hIL-10) and the effect of these interactions on its biologic activity were analyzed. It was demonstrated by affinity chromatography that hIL-10 binds strongly to heparin–agarose at physiological pH. Biosensor-based binding kinetic analysis indicated an equilibrium dissociation constant, Kd, of 54 nmol/L for this interaction. Human IL-10 stimulated CD16 and CD64 expression on the monocyte/macrophage population within peripheral blood mononuclear cells, with optimal concentrations between 1 and 10 ng/mL. Soluble heparin, heparan sulfate, chondroitin sulfate, and dermatan sulfate were shown to inhibit the hIL-10–induced expression of CD16 and CD64 in a concentration-dependent manner. Heparin and heparan sulfate were most effective with IC50 values of 100 to 500 μg/mL. Considerably higher concentrations of dermatan sulfate and chondroitin 4-sulfate were required with an IC50 of 2000 to 5000 μg/mL, whereas chondroitin 6-sulfate was essentially inactive. The antagonistic effect of heparin on hIL-10 activity was shown to be dependent on N-sulfation, inasmuch as de-N-sulfated heparin had little or no inhibitory effect on the IL-10– induced expression of CD16, whereas the effect of de-O-sulfated heparin was comparable to that of unmodified heparin. Furthermore, the inhibition of cell-bound proteoglycan sulfation reduced the hIL-10–mediated expression of CD16 molecules on monocytes/macrophages. Taken together, these findings support the hypothesis that soluble and cell-surface GAG and, in particular, their sulfate groups are important in binding and modulation of hIL-10 activity.

Heparin and heparan sulfate bind interleukin-10 and modulate its activity

Glycosaminoglycans (GAG) are a group of negatively charged molecules that have been shown to bind and directly regulate the bioactivity of growth factors and cytokines such as basic fibroblast growth factor, transforming growth factor-β, IL-7, and interferon-γ. The ability of GAG to interact with human IL-10 (hIL-10) and the effect of these interactions on its biologic activity were analyzed. It was demonstrated by affinity chromatography that hIL-10 binds strongly to heparin–agarose at physiological pH. Biosensor-based binding kinetic analysis indicated an equilibrium dissociation constant, Kd, of 54 nmol/L for this interaction. Human IL-10 stimulated CD16 and CD64 expression on the monocyte/macrophage population within peripheral blood mononuclear cells, with optimal concentrations between 1 and 10 ng/mL. Soluble heparin, heparan sulfate, chondroitin sulfate, and dermatan sulfate were shown to inhibit the hIL-10–induced expression of CD16 and CD64 in a concentration-dependent manner. Heparin and heparan sulfate were most effective with IC50 values of 100 to 500 μg/mL. Considerably higher concentrations of dermatan sulfate and chondroitin 4-sulfate were required with an IC50 of 2000 to 5000 μg/mL, whereas chondroitin 6-sulfate was essentially inactive. The antagonistic effect of heparin on hIL-10 activity was shown to be dependent on N-sulfation, inasmuch as de-N-sulfated heparin had little or no inhibitory effect on the IL-10– induced expression of CD16, whereas the effect of de-O-sulfated heparin was comparable to that of unmodified heparin. Furthermore, the inhibition of cell-bound proteoglycan sulfation reduced the hIL-10–mediated expression of CD16 molecules on monocytes/macrophages. Taken together, these findings support the hypothesis that soluble and cell-surface GAG and, in particular, their sulfate groups are important in binding and modulation of hIL-10 activity.

Chemokine blockade as a therapy for renal disease

Chemokines have been verified as inflammatory mediators of experimental nephritis by using anti-chemokine antibodies, chemokine receptor antagonists or targeted chemokine gene disruption. In human disease, chemokines are expressed in the kidney in association with inflammatory infiltrates. Chemokine blockade is thus a potentially novel approach to therapy of inflammatory renal disease. Several anti-chemokine strategies are under development. Effective use of anti-chemokine therapy for renal disease will require a precise understanding of the unique roles that individual chemokines have in renal pathology, and the genetic factors that regulate chemokine expression.

Inhibition of allergic late airway responses by inhaled heparin-derived oligosaccharides

Inhaled heparin has been shown to inhibit allergic bronchoconstriction in sheep that develop only acute responses to antigen (acute responders) but was ineffective in sheep that develop both acute and late airway responses (LAR) (dual responders). Because the antiallergic activity of heparin is molecular-weight dependent, we hypothesized that heparin-derived oligosaccharides (<2, 500) with potential anti-inflammatory activity may attenuate the LAR in the dual-responder sheep. Specific lung resistance was measured in 24 dual-responder sheep before and serially for 8 h after challenge with Ascaris suum antigen for demonstration of early airway response (EAR) and LAR, without and after treatment with inhaled medium-, low-, and ultralow-molecular-weight (ULMW) heparins and "non-anticoagulant" fractions (NAF) of heparin. Airway responsiveness was estimated before and 24 h postantigen as the cumulative provocating dose of carbachol that increased specific lung resistance by 400%. Only ULMW heparins caused a dose-dependent inhibition of antigen-induced EAR and LAR and postantigen airway hyperresponsiveness (AHR), whereas low- and medium-molecular-weight heparins were ineffective. The effects of ULMW heparin and ULMW NAF-heparin were comparable and inhibited the LAR and AHR even when administered "after" the antigen challenge. The ULMW NAF-heparin failed to inhibit the bronchoconstrictor response to histamine, carbachol, and leukotriene D(4), excluding a direct effect on airway smooth muscle. In six sheep, segmental antigen challenge caused a marked increase in bronchoalveolar lavage histamine, which was not prevented by inhaled ULMW NAF-heparin. The results of this study in the dual-responder sheep demonstrate that 1) the antiallergic activity of inhaled "fractionated" heparins is molecular-weight dependent, 2) only ULMW heparins inhibit the antigen-induced EAR and LAR and postantigen AHR, and 3) the antiallergic activity is mediated by nonanticoagulant fractions and resides in the ULMW chains of <2,500.