Heparin's anti-inflammatory effects require glucosamine 6-O-sulfation and are mediated by blockade of L- and P-selectins

Exploring the therapeutic role of early heparin administration in ARDS management: a MIMIC-IV database analysis

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a severe respiratory condition characterized by a high mortality rate, the management of which relies on supportive care and a profound understanding of its pathophysiology. Heparin, with its anticoagulant and potential anti-inflammatory properties, offers a new therapeutic opportunity for the treatment of ARDS.

METHODS

In this retrospective cohort study, we examined the MIMIC-IV database for ARDS patients who received prophylactic heparin within the first 72 h of ICU admission. Employing propensity score matching and inverse probability weighting (IPW) analysis, we evaluated the impact of early heparin use on patient outcomes, focusing on mortality rates.

RESULTS

Patients who received prophylactic heparin had a significantly lower in-hospital mortality rate compared to those who did not (13.55% vs 17.93%, HR = 0.71, 95% CI: 0.54-0.93, P = 0.012). This result remained significant after propensity score matching (12.75% vs 17.93%, HR = 0.65, 95% CI 0.47-0.90, P = 0.010). Analysis using five different statistical models indicated that early use of heparin significantly reduced the in-hospital mortality rate, with HR = 0.669 (95% CI 0.487-0.919, P = 0.013) in the doubly robust model without balanced covariates; HR = 0.705 (95% CI 0.515-0.965, P = 0.029) with all covariates considered; HR = 0.660 (95% CI 0.491-0.888, P = 0.006) in the propensity score (IPW) model; HR = 0.650 (95% CI 0.470-0.900, P = 0.010) in the propensity score matching model; and HR = 0.706 (95% CI 0.536-0.930, P = 0.013) in the multivariate Cox regression model. Secondary outcomes indicated that heparin use was also associated with reduced mortality rates at 60 days, and 90 days.

CONCLUSION

This research highlights that early prophylactic administration of heparin may substantially lower mortality in ARDS patients. These findings underscore the potential of heparin as a key component in the management of ARDS, offering a new perspective and novel strategies for clinical treatment.

Glomerular endothelial glycocalyx-derived heparan sulfate inhibits glomerular leukocyte influx and attenuates experimental glomerulonephritis

Proliferative forms of glomerulonephritis are characterized by the influx of leukocytes, albuminuria, and loss of kidney function. The glomerular endothelial glycocalyx is a thick carbohydrate layer that covers the endothelium and is comprised of heparan sulfate (HS), which plays a pivotal role in glomerular inflammation by facilitating endothelial-leukocyte trafficking. We hypothesize that the exogenous glomerular glycocalyx may reduce the glomerular influx of inflammatory cells during glomerulonephritis. Indeed, administration of mouse glomerular endothelial cell (mGEnC)-derived glycocalyx constituents, or the low-molecular-weight heparin enoxaparin, reduced proteinuria in mice with experimental glomerulonephritis. Glomerular influx of granulocytes and macrophages, as well as glomerular fibrin deposition, was reduced by the administration of mGEnC-derived glycocalyx constituents, thereby explaining the improved clinical outcome. HS_glx also inhibited granulocyte adhesion to human glomerular endothelial cells in vitro. Notably, a specific HS_glx fraction inhibited both CD11b and L-selectin binding to activated mGEnCs. Mass spectrometry analysis of this specific fraction revealed six HS oligosaccharides, ranging from tetra- to hexasaccharides with 2-7 sulfates. In summary, we demonstrate that exogenous HS_glx reduces albuminuria during glomerulonephritis, which is possibly mediated via multiple mechanisms. Our results justify the further development of structurally defined HS-based therapeutics for patients with (acute) inflammatory glomerular diseases, which may be applicable to non-renal inflammatory diseases as well.

Heparan sulfate proteoglycan in Alzheimer's disease: aberrant expression and functions in molecular pathways related to amyloid-β metabolism

Alzheimer's disease (AD) is the most common form of dementia. Currently, there is no effective treatment for AD, as its etiology remains poorly understood. Mounting evidence suggests that the accumulation and aggregation of amyloid-β peptides (Aβ), which constitute amyloid plaques in the brain, is critical for initiating and accelerating AD pathogenesis. Considerable efforts have been dedicated to shedding light on the molecular basis and fundamental origins of the impaired Aβ metabolism in AD. Heparan sulfate (HS), a linear polysaccharide of the glycosaminoglycan family, co-deposits with Aβ in plaques in the AD brain, directly binds and accelerates Aβ aggregation, and mediates Aβ internalization and cytotoxicity. Mouse model studies demonstrate that HS regulates Aβ clearance and neuroinflammation in vivo. Previous reviews have extensively explored these discoveries. Here, this review focuses on the recent advancements in understanding abnormal HS expression in the AD brain, the structural aspects of HS-Aβ interaction, and the molecules involved in modulating Aβ metabolism through HS interaction. Furthermore, this review presents a perspective on the potential effects of abnormal HS expression on Aβ metabolism and AD pathogenesis. In addition, the review highlights the importance of conducting further research to differentiate the spatiotemporal components of HS structure and function in the brain and AD pathogenesis.

Heparan sulfates and heparan sulfate binding proteins in sepsis

Heparan sulfates (HSs) are the main components in the glycocalyx which covers endothelial cells and modulates vascular homeostasis through interactions with multiple Heparan sulfate binding proteins (HSBPs). During sepsis, heparanase increases and induces HS shedding. The process causes glycocalyx degradation, exacerbating inflammation and coagulation in sepsis. The circulating heparan sulfate fragments may serve as a host defense system by neutralizing dysregulated Heparan sulfate binding proteins or pro-inflammatory molecules in certain circumstances. Understanding heparan sulfates and heparan sulfate binding proteins in health and sepsis is critical to decipher the dysregulated host response in sepsis and advance drug development. In this review, we will overview the current understanding of HS in glycocalyx under septic condition and the dysfunctional heparan sulfate binding proteins as potential drug targets, particularly, high mobility group box 1 (HMGB1) and histones. Moreover, several drug candidates based on heparan sulfates or related to heparan sulfates, such as heparanase inhibitors or heparin-binding protein (HBP), will be discussed regarding their recent advances. By applying chemical or chemoenzymatic approaches, the structure-function relationship between heparan sulfates and heparan sulfate binding proteins is recently revealed with structurally defined heparan sulfates. Such homogenous heparan sulfates may further facilitate the investigation of the role of heparan sulfates in sepsis and the development of carbohydrate-based therapy.

SAGE: Novel Therapy to Reduce Inflammation in a Naturally Occurring-Dog Model of Periodontal Disease

Objective

Methods

Results

Conclusion

Effect of Nebulized Heparin on Weaning off Intubated Patients with Acute Respiratory Distress Syndrome (ARDS) Admitted to Intensive Care Unit (ICU): A Randomized Clinical Trial

Background: Acute respiratory distress syndrome (ARDS) treatment is based on supportive care such as mechanical ventilation, prophylaxis of stress ulcer, prophylaxis of deep vein thrombosis (DVT), nutritional support, and treatment of underlying disease. Objectives: We aimed to investigate the effects of nebulized heparin on weaning off intubated ARDS patients admitted to the intensive care unit (ICU). Methods: In this double-blind clinical trial study, 60 patients with ARDS receiving routine care according to the ARDS protocol were randomly assigned into two groups: intervention group (receiving nebulized heparin 5000 u/BD for one week) and control group (receiving nebulized sterile water 2 cc/BD for one week). The respiratory index (PaO2/FiO2), pulmonary shunt percentage (measured by ABG), tidal volume, minute ventilation, admission duration in the ICU, and days of mechanical ventilation required were recorded for each patient for one week. Results: There was no significant difference in demographic data between the two groups. Inhaled heparin in patients with ARDS could significantly increase the respiratory index (PaO2/FiO2) and decrease pulmonary shunt percentage, minute ventilation, and tidal volume. It also significantly reduced the number of admission days in the ICU and the need for mechanical ventilation. Conclusions: The result of the present study showed that inhaled heparin in intubated ARDS patients admitted to the ICU improved respiratory and pulmonary status and reduced the need for mechanical ventilation and admission days in the ICU. Nebulizing heparin, as an anti-inflammatory and anti-coagulant agent, is an effective and safe medication for ARDS patients on mechanical ventilation.

Heparan Sulfate Facilitates Spike Protein-Mediated SARS-CoV-2 Host Cell Invasion and Contributes to Increased Infection of SARS-CoV-2 G614 Mutant and in Lung Cancer

The severe acute respiratory syndrome (SARS)-like coronavirus disease (COVID-19) is caused by SARS-CoV-2 and has been a serious threat to global public health with limited treatment. Cellular heparan sulfate (HS) has been found to bind SARS-CoV-2 spike protein (SV2-S) and co-operate with cell surface receptor angiotensin-converting enzyme 2 (ACE2) to mediate SARS-CoV-2 infection of host cells. In this study, we determined that host cell surface SV2-S binding depends on and correlates with host cell surface HS expression. This binding is required for SARS-Cov-2 virus to infect host cells and can be blocked by heparin lyase, HS antagonist surfen, heparin, and heparin derivatives. The binding of heparin/HS to SV2-S is mainly determined by its overall sulfation with potential, minor contribution of specific SV2-S binding motifs. The higher binding affinity of SV2-S G614 mutant to heparin and upregulated HS expression may be one of the mechanisms underlying the higher infectivity of the SARS-CoV-2 G614 variant and the high vulnerability of lung cancer patients to SARS-CoV-2 infection, respectively. The higher host cell infection by SARS-CoV-2 G614 variant pseudovirus and the increased infection caused by upregulated HS expression both can be effectively blocked by heparin lyase and heparin, and possibly surfen and heparin derivatives too. Our findings support blocking HS-SV2-S interaction may provide one addition to achieve effective prevention and/treatment of COVID-19.

Effects of sevoflurane and propofol anesthesia on intraoperative endothelial cell function in patients undergoing laparoscopic cholecystectomy

Objectives

To investigate the effects of sevoflurane and propofol anesthesia on inflammatory or anti-inflammatory responses in patients undergoing laparoscopic cholecystectomy (LC).

Methods

Patients undergoing LC (n = 23) were divided into sevoflurane (S) (n = 11) and propofol (P) (n = 12) anesthesia groups. A blood sample was taken before induction (T0), after induction but before pneumoperitoneum (T1), 15 minutes after pneumoperitoneum (T2), immediately after extubation (T3), and 30 minutes after extubation (T4). P-selectin-positive platelets and intercellular cell adhesion molecule-1 (ICAM-1)-positive lymphocytes, and plasma P-selectin, ICAM-1 and thrombomodulin (TM) levels were analyzed.

Results

Sevoflurane significantly increased P-selectin expression in platelets at T2, T3, and T4 and in plasma at T1, T2, T3, and T4, but it did not affect ICAM-1 and TM. Propofol had no significant effects on P-selectin, ICAM-1, and TM expression during anesthesia and surgery. P-selectin, ICAM-1, and TM expression was higher in the S compared with P group at T1, T2, and T3 for platelet P-selectin; T2 and T4 for plasma P-selectin; T1 and T2 for lymphocyte ICAM-1; and T1, T2, and T3 for plasma TM.

Conclusions

Propofol anesthesia can delay the inflammatory reactions during laparoscopic surgery and better maintain the structure stability and function in vascular endothelial cells.

Divergent Mast Cell Responses Modulate Antiviral Immunity During Influenza Virus Infection

Influenza A virus (IAV) is a respiratory pathogen that infects millions of people each year. Both seasonal and pandemic strains of IAV are capable of causing severe respiratory disease with a high risk of respiratory failure and opportunistic secondary infection. A strong inflammatory cytokine response is a hallmark of severe IAV infection. The widespread tissue damage and edema in the lung during severe influenza is largely attributed to an overexuberant production of inflammatory cytokines and cell killing by resident and infiltrating leukocytes. Mast cells (MCs) are a sentinel hematopoietic cell type situated at mucosal sites, including the lung. Poised to react immediately upon detecting infection, MCs produce a vast array of immune modulating molecules, including inflammatory cytokines, chemokines, and proteases. As such, MCs have been implicated as a source of the immunopathology observed in severe influenza. However, a growing body of evidence indicates that MCs play an essential role not only in inducing an inflammatory response but in suppressing inflammation as well. MC-derived immune suppressive cytokines are essential to the resolution of a number of viral infections and other immune insults. Absence of MCs prolongs infection, exacerbates tissue damage, and contributes to dissemination of the pathogen to other tissues. Production of cytokines such as IL-10 and IL-6 by MCs is essential for mitigating the inflammation and tissue damage caused by innate and adaptive immune cells alike. The two opposing functions of MCs—one pro-inflammatory and one anti-inflammatory—distinguish MCs as master regulators of immunity at the site of infection. Amongst the first cells to respond to infection or injury, MCs persist for the duration of the infection, modulating the recruitment, activation, and eventual suppression of other immune cells. In this review, we will discuss the immune modulatory roles of MCs over the course of viral infection and propose that the immune suppressive mediators produced by MCs are vital to minimizing immunopathology during influenza infection.

The glycocalyx: a central regulator of vascular function

The endothelial glycocalyx is a specialized extracellular matrix that covers the apical side of vascular endothelial cells, projecting into the lumen of blood vessels. The composition of the glycocalyx has been studied in great detail, and it is known to be composed of a mixture of proteoglycans, glycosaminoglycans, and glycoproteins. Although this structure was once believed to be a passive physical barrier, it is now recognized as a multifunctional and dynamic structure that participates in many vascular processes, including but not limited to vascular permeability, inflammation, thrombosis, mechanotransduction, and cytokine signaling. Because of its participation in many physiological and pathophysiological states, comprehensive knowledge of the glycocalyx will aid future vascular biologists in their research. With that in mind, this review discusses the biochemical structure of the glycocalyx and its function in many vascular physiological processes. We also briefly review a more recent discovery in glycocalyx biology, the placental glycocalyx.

Elucidating the Interactions Between Heparin/Heparan Sulfate and SARS-CoV-2-Related Proteins-An Important Strategy for Developing Novel Therapeutics for the COVID-19 Pandemic

Owing to the high mortality and the spread rate, the infectious disease caused by SARS-CoV-2 has become a major threat to public health and social economy, leading to over 70 million infections and 1. 6 million deaths to date. Since there are currently no effective therapeutic or widely available vaccines, it is of urgent need to look for new strategies for the treatment of SARS-CoV-2 infection diseases. Binding of a viral protein onto cell surface heparan sulfate (HS) is generally the first step in a cascade of interaction that is required for viral entry and the initiation of infection. Meanwhile, interactions of selectins and cytokines (e.g., IL-6 and TNF-α) with HS expressed on endothelial cells are crucial in controlling the recruitment of immune cells during inflammation. Thus, structurally defined heparin/HS and their mimetics might serve as potential drugs by competing with cell surface HS for the prevention of viral adhesion and modulation of inflammatory reaction. In this review, we will elaborate coronavirus invasion mechanisms and summarize the latest advances in HS-protein interactions, especially proteins relevant to the process of coronavirus infection and subsequent inflammation. Experimental and computational techniques involved will be emphasized.

Nebulised heparin for patients with or at risk of acute respiratory distress syndrome: a multicentre, randomised, double-blind, placebo-controlled phase 3 trial

Background

Mechanical ventilation in intensive care for 48 h or longer is associated with the acute respiratory distress syndrome (ARDS), which might be present at the time ventilatory support is instituted or develop afterwards, predominantly during the first 5 days. Survivors of prolonged mechanical ventilation and ARDS are at risk of considerably impaired physical function that can persist for years. An early pathogenic mechanism of lung injury in mechanically ventilated, critically ill patients is inflammation-induced pulmonary fibrin deposition, leading to thrombosis of the microvasculature and hyaline membrane formation in the air sacs. The main aim of this study was to determine if nebulised heparin, which targets fibrin deposition, would limit lung injury and thereby accelerate recovery of physical function in patients with or at risk of ARDS.

Methods

The Can Heparin Administration Reduce Lung Injury (CHARLI) study was an investigator-initiated, multicentre, double-blind, randomised phase 3 trial across nine hospitals in Australia. Adult intensive care patients on invasive ventilation, with impaired oxygenation defined by a PaO₂/FiO₂ ratio of less than 300, and with the expectation of invasive ventilation beyond the next calendar day were recruited. Key exclusion criteria were heparin allergy, pulmonary bleeding, and platelet count less than 50 X 10⁹/L. Patients were randomly assigned 1:1, with stratification by site and using blocks of variable size and random seed, via a web-based system, to either unfractionated heparin sodium 25 000 IU in 5 mL or identical placebo (sodium chloride 0·9% 5 mL), administered using a vibrating mesh membrane nebuliser every 6 h to day 10 while invasively ventilated. Patients, clinicians, and investigators were masked to treatment allocation. The primary outcome was the Short Form 36 Health Survey Physical Function Score (out of 100) of survivors at day 60. Prespecified secondary outcomes, which are exploratory, included development of ARDS to day 5 among at-risk patients, deterioration of the Murray Lung Injury Score (MLIS) to day 5, mortality at day 60, residence of survivors at day 60, and serious adverse events. Analyses followed the intention-to-treat principle. There was no imputation of missing data. The trial is registered with the Australian and New Zealand Clinical Trials Register, number ACTRN12612000418875 .

Findings

Between Sept 4, 2012, and Aug 23, 2018, 256 patients were randomised. Final follow-up was on Feb 25, 2019. We excluded three patients who revoked consent and one ineligible participant who received no intervention. Of 252 patients included in data analysis, the mean age was 58 years (SD 15), 157 (62%) were men, and 118 (47%) had ARDS. 128 (51%) patients were assigned to the heparin group and 124 (49%) to the placebo group, all of whom received their assigned intervention. Survivors in the heparin group (n=97) had similar SF-36 Physical Function Scores at day 60 compared to the placebo group (n=94; mean 53·6 [SD 31·6] vs 48·7 [35·7]; difference 4·9 [95% CI −4·8 to 14·5]; p=0·32). Compared with the placebo group, the heparin group had fewer cases of ARDS develop to day 5 among the at-risk patients (nine [15%] of 62 patients vs 21 [30%] of 71 patients; hazard ratio 0·46 [95% CI 0·22 to 0·98]; p=0·0431), less deterioration of the MLIS to day 5 (difference −0·14 [–0·26 to −0·02]; p=0·0215), similar day 60 mortality (23 [18%] of 127 patients vs 18 [15%] of 123 patients; odds ratio [OR] 1·29 [95% CI 0·66 to 2·53]; p=0·46), and more day 60 survivors at home (86 [87%] of 99 patients vs 73 [73%] of 100 patients; OR 2·45 [1·18 to 5·08]; p=0·0165). A similar number of serious adverse events occurred in each group (seven [5%] of 128 patients in the heparin group vs three [2%] of 124 patients in the placebo group; OR 2·33 [0·59 to 9·24]; p=0·23), which were a transient increase in airway pressure during nebulisation (n=3 in the heparin group), major non-pulmonary bleeding (n=2 in each group), haemoptysis (n=1 in the heparin group), tracheotomy site bleeding (n=1 in the heparin group), and hypoxaemia during nebulisation (n=1 in the placebo group).

Interpretation

In patients with or at risk of ARDS, nebulised heparin did not improve self-reported performance of daily physical activities, but was well tolerated and exploratory outcomes suggest less progression of lung injury and earlier return home. Further research is justified to establish if nebulised heparin accelerates recovery in those who have or are at risk of ARDS.

Funding

Rowe Family Foundation, TR and RB Ditchfield Medical Research Endowment Fund, Patricia Madigan Charitable Trust, and The J and R McGauran Trust Fund.

Rationale for the Role of Heparin and Related GAG Antithrombotics in COVID-19 Infection

The SARS-CoV-2 pandemic has focused attention on prevention, restriction and treatment methods that are acceptable worldwide. This means that they should be simple and inexpensive. This review examines the possible role of glycosaminoglycan (GAG) antithrombotics in the treatment of COVID-19. The pathophysiology of this disease reveals a complex interplay between the hemostatic and immune systems that can be readily disrupted by SARS-CoV-2. Some of the GAG antithrombotics also possess immune-modulatory actions and since they are relatively inexpensive they could play an important role in the management of COVID-19 and its complications.

Guidance for the Management of Patients with Vascular Disease or Cardiovascular Risk Factors and COVID-19: Position Paper from VAS-European Independent Foundation in Angiology/Vascular Medicine

COVID-19 is also manifested with hypercoagulability, pulmonary intravascular coagulation, microangiopathy, and venous thromboembolism (VTE) or arterial thrombosis. Predisposing risk factors to severe COVID-19 are male sex, underlying cardiovascular disease, or cardiovascular risk factors including noncontrolled diabetes mellitus or arterial hypertension, obesity, and advanced age. The VAS-European Independent Foundation in Angiology/Vascular Medicine draws attention to patients with vascular disease (VD) and presents an integral strategy for the management of patients with VD or cardiovascular risk factors (VD-CVR) and COVID-19. VAS recommends (1) a COVID-19-oriented primary health care network for patients with VD-CVR for identification of patients with VD-CVR in the community and patients' education for disease symptoms, use of eHealth technology, adherence to the antithrombotic and vascular regulating treatments, and (2) close medical follow-up for efficacious control of VD progression and prompt application of physical and social distancing measures in case of new epidemic waves. For patients with VD-CVR who receive home treatment for COVID-19, VAS recommends assessment for (1) disease worsening risk and prioritized hospitalization of those at high risk and (2) VTE risk assessment and thromboprophylaxis with rivaroxaban, betrixaban, or low-molecular-weight heparin (LMWH) for those at high risk. For hospitalized patients with VD-CVR and COVID-19, VAS recommends (1) routine thromboprophylaxis with weight-adjusted intermediate doses of LMWH (unless contraindication); (2) LMWH as the drug of choice over unfractionated heparin or direct oral anticoagulants for the treatment of VTE or hypercoagulability; (3) careful evaluation of the risk for disease worsening and prompt application of targeted antiviral or convalescence treatments; (4) monitoring of D-dimer for optimization of the antithrombotic treatment; and (5) evaluation of the risk of VTE before hospital discharge using the IMPROVE-D-dimer score and prolonged post-discharge thromboprophylaxis with rivaroxaban, betrixaban, or LMWH.

Selectins-The Two Dr. Jekyll and Mr. Hyde Faces of Adhesion Molecules-A Review

Selectins belong to a group of adhesion molecules that fulfill an essential role in immune and inflammatory responses and tissue healing. Selectins are glycoproteins that decode the information carried by glycan structures, and non-covalent interactions of selectins with these glycan structures mediate biological processes. The sialylated and fucosylated tetrasaccharide sLe^x is an essential glycan recognized by selectins. Several glycosyltransferases are responsible for the biosynthesis of the sLe^x tetrasaccharide. Selectins are involved in a sequence of interactions of circulated leukocytes with endothelial cells in the blood called the adhesion cascade. Recently, it has become evident that cancer cells utilize a similar adhesion cascade to promote metastases. However, like Dr. Jekyll and Mr. Hyde’s two faces, selectins also contribute to tissue destruction during some infections and inflammatory diseases. The most prominent function of selectins is associated with the initial stage of the leukocyte adhesion cascade, in which selectin binding enables tethering and rolling. The first adhesive event occurs through specific non-covalent interactions between selectins and their ligands, with glycans functioning as an interface between leukocytes or cancer cells and the endothelium. Targeting these interactions remains a principal strategy aimed at developing new therapies for the treatment of immune and inflammatory disorders and cancer. In this review, we will survey the significant contributions to and the current status of the understanding of the structure of selectins and the role of selectins in various biological processes. The potential of selectins and their ligands as therapeutic targets in chronic and acute inflammatory diseases and cancer will also be discussed. We will emphasize the structural characteristic of selectins and the catalytic mechanisms of glycosyltransferases involved in the biosynthesis of glycan recognition determinants. Furthermore, recent achievements in the synthesis of selectin inhibitors will be reviewed with a focus on the various strategies used for the development of glycosyltransferase inhibitors, including substrate analog inhibitors and transition state analog inhibitors, which are based on knowledge of the catalytic mechanism.

HS and Inflammation: A Potential Playground for the Sulfs?

Heparan sulfate (HS) is a complex polysaccharide abundantly found in extracellular matrices and cell surfaces. HS participates in major cellular processes, through its ability to bind and modulate a wide array of signaling proteins. HS/ligand interactions involve saccharide domains of specific sulfation pattern. Assembly of such domains is orchestrated by a complex biosynthesis machinery and their structure is further regulated at the cell surface by post-synthetic modifying enzymes. Amongst them, extracellular sulfatases of the Sulf family catalyze the selective removal of 6-O-sulfate groups, which participate in the binding of many proteins. As such, increasing interest arose on the regulation of HS biological properties by the Sulfs. However, studies of the Sulfs have so far been essentially restricted to the fields of development and tumor progression. The aim of this review is to survey recent data of the literature on the still poorly documented role of the Sulfs during inflammation, and to widen the perspectives for the study of this intriguing regulatory mechanism toward new physiopathological processes.

Characterization of the interaction between platelet factor 4 and homogeneous synthetic low molecular weight heparins

BACKGROUND

Heparins are usually produced from animal tissues. It is now possible to synthesize heparins. This provides the abilities to overcome shortages of heparin, to optimize biological effects, and to reduce adverse drug effects. Heparins interact with platelet factor 4 (PF4), which can induce an immune response causing thrombocytopenia. This side effect is called heparin-induced thrombocytopenia (HIT). We characterized the interaction of PF4 and HIT antibodies with oligosaccharides of 6-, 8-, 10-, and 12-mer size and a hypersulfated 12-mer (S12-mer).

METHODS

We utilized multiple methodologies including isothermal calorimetry, circular dichroism spectroscopy, single molecule force spectroscopy (SMFS), enzyme immunosorbent assay (EIA), and platelet aggregation test to characterize the interaction of synthetic heparin analogs with PF4 and anti-PF4/heparin antibodies.

RESULTS

The synthetic heparin-like compounds display stronger binding characteristics to PF4 than animal-derived heparins of corresponding lengths. Upon complexation with PF4, 6-mer and S12-mer heparins showed much lower enthalpy, induced less conformational changes in PF4, and interacted with weaker forces than 8-, 10-, and 12-mer heparins. Anti-PF4/heparin antibodies bind more weakly to complexes formed between PF4 and heparins ≤ 8-mer than with complexes formed between PF4 and heparins ≥ 10-mer. Addition of one sulfate group to the 12-mer resulted in a S12-mer, which showed substantial changes in its binding characteristics to PF4.

CONCLUSIONS

We provide a template for characterizing interactions of newly developed heparin-based anticoagulant drugs with proteins, especially PF4 and the resulting potential antigenicity.

Heparin Forms Polymers with Cell-free DNA Which Elongate Under Shear in Flowing Blood

Heparin is a widely used anticoagulant which inhibits factor Xa and thrombin through potentiation of antithrombin. We recently identified that the nucleic acid stain SYTOX reacts with platelet polyphosphate due to molecular similarities, some of which are shared by heparin. We attempted to study heparin in flowing blood by live-cell fluorescence microscopy, using SYTOX for heparin visualisation. Immunostaining was performed with monoclonal antibodies directed against various heparin-binding proteins. In addition, we studied modulation of heparin activity in coagulation assays, as well its effects on fibrin formation under flow in recalcified whole blood. We found that SYTOX-positive polymers appear in heparinised blood under flow. These polymers typically associate with platelet aggregates and their length (reversibly) increases with shear rate. Immunostaining revealed that of the heparin-binding proteins assessed, they only contain histones. In coagulation assays and flow studies on fibrin formation, we found that addition of exogenous histones reverses the anticoagulant effects of heparin. Furthermore, the polymers do not appear in the presence of DNase I, heparinase I/III, or the heparin antidote protamine. These findings suggest that heparin forms polymeric complexes with cell-free DNA in whole blood through a currently unidentified mechanism.

Loss of endothelial sulfatase-1 after experimental sepsis attenuates subsequent pulmonary inflammatory responses

Sepsis patients are at increased risk for hospital-acquired pulmonary infections, potentially due to postseptic immunosuppression known as the compensatory anti-inflammatory response syndrome (CARS). CARS has been attributed to leukocyte dysfunction, with an unclear role for endothelial cells. The pulmonary circulation is lined by an endothelial glycocalyx, a heparan sulfate-rich layer essential to pulmonary homeostasis. Heparan sulfate degradation occurs early in sepsis, leading to lung injury. Endothelial synthesis of new heparan sulfates subsequently allows for glycocalyx reconstitution and endothelial recovery. We hypothesized that remodeling of the reconstituted endothelial glycocalyx, mediated by alterations in the endothelial machinery responsible for heparan sulfate synthesis, contributes to CARS. Seventy-two hours after experimental sepsis, coincident with glycocalyx reconstitution, mice demonstrated impaired neutrophil and protein influx in response to intratracheal lipopolysaccharide (LPS). The postseptic reconstituted glycocalyx was structurally remodeled, with enrichment of heparan sulfate disaccharides sulfated at the 6-O position of glucosamine. Increased 6-O-sulfation coincided with loss of endothelial sulfatase-1 (Sulf-1), an enzyme that specifically removes 6-O-sulfates from heparan sulfate. Intravenous administration of Sulf-1 to postseptic mice restored the pulmonary response to LPS, suggesting that loss of Sulf-1 was necessary for postseptic suppression of pulmonary inflammation. Endothelial-specific knockout mice demonstrated that loss of Sulf-1 was not sufficient to induce immunosuppression in non-septic mice. Knockdown of Sulf-1 in human pulmonary microvascular endothelial cells resulted in downregulation of the adhesion molecule ICAM-1. Taken together, our study indicates that loss of endothelial Sulf-1 is necessary for postseptic suppression of pulmonary inflammation, representing a novel endothelial contributor to CARS.

Low-molecular-weight-heparin increases Th1- and Th17-associated chemokine levels during pregnancy in women with unexplained recurrent pregnancy loss: a randomised controlled trial

Low-molecular-weight heparin (LMWH) is widely used to treat recurrent pregnancy loss (RPL) because of its anti-coagulant effects. Although in vitro studies have suggested additional immunological effects, these are debated. We therefore investigated whether LMWH could modulate immune responses in vivo during pregnancy of women with unexplained RPL. A Swedish open multi-centre randomised controlled trial included 45 women treated with tinzaparin and 42 untreated women. Longitudinally collected plasma samples were obtained at gestational weeks (gw) 6, 18, 28 and 34 and analysed by multiplex bead technology for levels of 11 cytokines and chemokines, chosen to represent inflammation and T-helper subset-associated immunity. Mixed linear models test on LMWH-treated and untreated women showed differences during pregnancy of the Th1-associated chemokines CXCL10 (p = 0.01), CXCL11 (p < 0.001) and the Th17-associated chemokine CCL20 (p = 0.04), while CCL2, CCL17, CCL22, CXCL1, CXCL8, CXCL12, CXCL13 and IL-6 did not differ. Subsequent Student's t-test showed significantly higher plasma levels of CXCL10 and CXCL11 in treated than untreated women at gw 28 and 34. The consistent increase in the two Th1-associated chemokines suggests a potential proinflammatory and unfavourable effect of LMWH treatment during later stages of pregnancy, when Th1 immunity is known to disrupt immunological tolerance.

L-selectin: A Major Regulator of Leukocyte Adhesion, Migration and Signaling

L-selectin (CD62L) is a type-I transmembrane glycoprotein and cell adhesion molecule that is expressed on most circulating leukocytes. Since its identification in 1983, L-selectin has been extensively characterized as a tethering/rolling receptor. There is now mounting evidence in the literature to suggest that L-selectin plays a role in regulating monocyte protrusion during transendothelial migration (TEM). The N-terminal calcium-dependent (C-type) lectin domain of L-selectin interacts with numerous glycans, including sialyl Lewis X (sLe^x) for tethering/rolling and proteoglycans for TEM. Although the signals downstream of L-selectin-dependent adhesion are poorly understood, they will invariably involve the short 17 amino acid cytoplasmic tail. In this review we will detail the expression of L-selectin in different immune cell subsets, and its influence on cell behavior. We will list some of the diverse glycans known to support L-selectin-dependent adhesion, within luminal and abluminal regions of the vessel wall. We will describe how each domain within L-selectin contributes to adhesion, migration and signal transduction. A significant focus on the L-selectin cytoplasmic tail and its proposed contribution to signaling via the ezrin-radixin-moesin (ERM) family of proteins will be outlined. Finally, we will discuss how ectodomain shedding of L-selectin during monocyte TEM is essential for the establishment of front-back cell polarity, bestowing emigrated cells the capacity to chemotax toward sites of damage.

Antithrombotics from the Sea: Polysaccharides and Beyond

Marine organisms exhibit some advantages as a renewable source of potential drugs, far beyond chemotherapics. Particularly, the number of marine natural products with antithrombotic activity has increased in the last few years, and reports show a wide diversity in scaffolds, beyond the polysaccharide framework. While there are several reviews highlighting the anticoagulant and antithrombotic activities of marine-derived sulfated polysaccharides, reports including other molecules are sparse. Therefore, the present paper provides an update of the recent progress in marine-derived sulfated polysaccharides and quotes other scaffolds that are being considered for investigation due to their antithrombotic effect.

Characterization and Quantification of Highly Sulfated Glycosaminoglycan Isomers by Gated-Trapped Ion Mobility Spectrometry Negative Electron Transfer Dissociation MS/MS

Glycosaminoglycans (GAGs) play vital roles in many biological processes and are naturally present as complex mixtures of polysaccharides with tremendous structural heterogeneity, including many structural isomers. Mass spectrometric analysis of GAG isomers, in particular highly sulfated heparin (Hep) and heparan sulfate (HS), is challenging because of their structural similarity and facile sulfo losses during analysis. Herein, we show that highly sulfated Hep/HS isomers may be resolved by gated-trapped ion mobility spectrometry (gated-TIMS) with negligible sulfo losses. Subsequent negative electron transfer dissociation (NETD) tandem mass spectrometry (MS/MS) analysis of TIMS-separated Hep/HS isomers generated extensive glycosidic and cross-ring fragments for confident isomer differentiation and structure elucidation. The high mobility resolution and preservation of labile sulfo modifications afforded by gated-TIMS MS analysis also allowed relative quantification of highly sulfated heparin isomers. These results show that the gated-TIMS-NETD MS/MS approach is useful for both qualitative and quantitative analysis of highly sulfated Hep/HS compounds in a manner not possible with other techniques.

Recombinant Heparin-New Opportunities

Heparin and heparan sulfate (HS) are polydisperse mixtures of polysaccharide chains between 5 and 50 kDa. Sulfate modifications to discreet regions along the chains form protein binding sites involved in cell signaling cascades and other important cellular physiological and pathophysiological functions. Specific protein affinities of the chains vary among different tissues and are determined by the arrangements of sulfated residues in discreet regions along the chains which in turn appear to be determined by the expression levels of particular enzymes in the biosynthetic pathway. Although not all the rules governing synthesis and modification are known, analytical procedures have been developed to determine composition, and all of the biosynthetic enzymes have been identified and cloned. Thus, through cell engineering, it is now possible to direct cellular synthesis of heparin and HS to particular compositions and therefore particular functional characteristics. For example, directing heparin producing cells to reduce the level of a particular type of polysaccharide modification may reduce the risk of heparin induced thrombocytopenia (HIT) without reducing the potency of anticoagulation. Similarly, HS has been linked to several biological areas including wound healing, cancer and lipid metabolism among others. Presumably, these roles involve specific HS compositions that could be produced by engineering cells. Providing HS reagents with a range of identified compositions should help accelerate this research and lead to new clinical applications for specific HS compositions. Here I review progress in engineering CHO cells to produce heparin and HS with compositions directed to improved properties and advancing medical research.

Heparan Sulfate Mimetics in Cancer Therapy: The Challenge to Define Structural Determinants and the Relevance of Targets for Optimal Activity

Beyond anticoagulation, the therapeutic potential of heparin derivatives and heparan sulfate (HS) mimetics (functionally defined HS mimetics) in oncology is related to their ability to bind and modulate the function of a vast array of HS-binding proteins with pivotal roles in cancer growth and progression. The definition of structural/functional determinants and the introduction of chemical modifications enabled heparin derivatives to be identified with greatly reduced or absent anticoagulant activity, but conserved/enhanced anticancer activity. These studies paved the way for the disclosure of structural requirements for the inhibitory effects of HS mimetics on heparanase, selectins, and growth factor receptor signaling, as well as for the limitation of side effects. Actually, HS mimetics affect the tumor biological behavior via a multi-target mechanism of action based on their effects on tumor cells and various components of the tumor microenvironment. Emerging evidence indicates that immunomodulation can participate in the antitumor activity of these agents. Significant ability to enhance the antitumor effects of combination treatments with standard therapies was shown in several tumor models. While the first HS mimetics are undergoing early clinical evaluation, an improved understanding of the molecular contexts favoring the antitumor action in certain malignancies or subgroups is needed to fully exploit their potential.

A mutant-cell library for systematic analysis of heparan sulfate structure-function relationships

Heparan sulfate (HS) is a complex linear polysaccharide that modulates a wide range of biological functions. Elucidating the structure-function relationship of HS has been challenging. Here we report the generation of an HS-mutant mouse lung endothelial cell library by systematic deletion of HS genes expressed in the cell. We used this library to (1) determine that the strictly defined fine structure of HS, not its overall degree of sulfation, is more important for FGF2-FGFR1 signaling; (2) define the epitope features of commonly used anti-HS phage display antibodies; and (3) delineate the fine inter-regulation networks by which HS genes modify HS and chain length in mammalian cells at a cell-type-specific level. Our mutant-cell library will allow robust and systematic interrogation of the roles and related structures of HS in a cellular context.

Cerebral Edema and Neurological Recovery after Traumatic Brain Injury Are Worsened if Accompanied by a Concomitant Long Bone Fracture

Progression of severe traumatic brain injury (TBI) is associated with worsening cerebral inflammation, but it is unknown how a concomitant bone fracture (FX) affects this progression. Enoxaparin (ENX), a low molecular weight heparin often used for venous thromboembolic prophylaxis, decreases penumbral leukocyte (LEU) mobilization in isolated TBI and improves neurological recovery. We investigated if TBI accompanied by an FX worsens LEU-mediated cerebral inflammation and if ENX alters this process. CD1 male mice underwent controlled cortical impact (CCI) or sham craniotomy with or without an open tibial FX, and received either ENX (1 mg/kg, three times/day) or saline for 2 days following injury. Randomization defined four groups (Sham, CCI, CCI+FX, CCI+FX+ENX, n = 10/group). Two days after CCI, neurological recovery was assessed with the Garcia Neurological Test (GNT); intravital microscopy (LEU rolling and adhesion, microvascular leakage) and blood hemoglobin levels were also evaluated. Penumbral cerebral neutrophil sequestration (Ly-6G immunohistochemistry [IHC]) were evaluated post-mortem. In vivo LEU rolling was greater in CCI+FX (45.2 ± 4.8 LEUs/100 μm/min) than in CCI alone (26.5 ± 3.1, p = 0.007), and was suppressed by ENX (23.2 ± 5.5, p = 0.003 vs. CCI + FX). Neurovascular permeability was higher in CCI+FX (71.1 ± 2.9%) than CCI alone (42.5 ± 2.3, p < 0.001). GNT scores were lower in CCI+FX (15.2 ± 0.2) than in CCI alone (16.3 ± 0.3, p < 0.001). Hemoglobin was lowest in the CCI+FX+ENX group, lower than in Sham or CCI. IHC demonstrated greatest polymorphonuclear neutrophil (PMN) invasion in CCI+FX in uninjured cerebral territories. A concomitant long bone FX worsens TBI-induced cerebral LEU mobilization, microvascular leakage, and cerebral edema, and impairs neurological recovery at 48 h. ENX suppresses this progression but may increase bleeding.

Programmable one-pot synthesis of heparin pentasaccharides enabling access to regiodefined sulfate derivatives

Heparin (H) and heparan sulfate (HS) belong to the glycosaminoglycan (GAG) family of oligosaccharides, and their sequences and sulfation patterns are known to regulate the functions of various proteins in biological processes. Among these, the 6-O-sulfation of HS/H contributes most significantly to the structural diversity and binding interactions. However, the synthesis of HS with defined sulfation patterns remains a major challenge. Herein, we report a highly efficient and programmable one-pot method for the synthesis of protected heparin pentasaccharides using thioglycoside building blocks with optimized relative reactivities to allow the selective deprotection and preparation of regiodefined sulfate derivatives.

The intertwined fates of inflammation and coagulation in glioma

Inflammation and coagulation are two intertwined pathways with evolutionary ties being traced back to the hemocyte, a single cell type in invertebrates that has functions in both the inflammatory and coagulation pathways. These systems have functioned together throughout evolution to provide a solid defence against infection, damaged cells and irritants. While these systems work in harmony the majority of the time, they can also become dysregulated or corrupted by tumours, enhancing tumour proliferation, invasion, dissemination and survival. This review aims to give a brief overview of how these systems work in harmony and how dysregulation of these systems aids in the development and progression of cancer, using glioma as an example.

The heparan sulfate proteoglycan grip on hyperlipidemia and atherosclerosis

Heparan sulfate proteoglycans are found at the cell surface and in the extracellular matrix, where they interact with a plethora of proteins involved in lipid homeostasis and inflammation. Over the last decade, new insights have emerged regarding the mechanism and biological significance of these interactions in the context of cardiovascular disease. The majority of cardiovascular disease-related deaths are caused by complications of atherosclerosis, a disease that results in narrowing of the arterial lumen, thereby reducing blood flow to critical levels in vital organs, such as the heart and brain. Here, we discuss novel insights into how heparan sulfate proteoglycans modulate risk factors such as hyperlipidemia and inflammation that drive the initiation and progression of atherosclerotic plaques to their clinical critical endpoint.

Mast Cells Exert Anti-Inflammatory Effects in an IL10-/- Model of Spontaneous Colitis

Mast cells are well established as divergent modulators of inflammation and immunosuppression, but their role in inflammatory bowel disease (IBD) remains to be fully defined. While previous studies have demonstrated a proinflammatory role for mast cells in acute models of chemical colitis, more recent investigations have shown that mast cell deficiency can exacerbate inflammation in spontaneous colitis models, thus suggesting a potential anti-inflammatory role of mast cells in IBD. Here, we tested the hypothesis that in chronic, spontaneous colitis, mast cells are protective. We compared colitis and intestinal barrier function in IL10^−/− mice to mast cell deficient/IL10^−/− (double knockout (DKO): Kit^Wsh/Wsh × IL10^−/−) mice. Compared with IL10^−/− mice, DKO mice exhibited more severe colitis as assessed by increased colitis scores, mucosal hypertrophy, intestinal permeability, and colonic cytokine production. PCR array analyses demonstrated enhanced expression of numerous cytokine and chemokine genes and downregulation of anti-inflammatory genes (e.g., Tgfb2, Bmp2, Bmp4, Bmp6, and Bmp7) in the colonic mucosa of DKO mice. Systemic reconstitution of DKO mice with bone marrow-derived mast cells resulted in significant amelioration of IL10^−/−-mediated colitis and intestinal barrier injury. Together, the results presented here demonstrate that mast cells exert anti-inflammatory properties in an established model of chronic, spontaneous IBD. Given the previously established proinflammatory role of mast cells in acute chemical colitis models, the present findings provide new insight into the divergent roles of mast cells in modulating inflammation during different stages of colitis. Further investigation of the mechanism of the anti-inflammatory role of the mast cells may elucidate novel therapies.

Effects of low molecular weight heparin on the polarization and cytokine profile of macrophages and T helper cells in vitro

Low molecular weight heparin (LMWH) is widely used in recurrent miscarriage treatment. The anti-coagulant effects are established, while immunological effects are not fully known. Our aim was to assess LMWH effects on activation and polarization of central regulatory immune cells from healthy women, and on placenta tissues from women undergoing elective abortions. Isolated blood monocytes and T helper (Th) cells under different activation and polarizing conditions were cultured with or without LMWH. Flow cytometry showed that LMWH exposure induced increased expression of HLA-DR and CD206 in macrophages. This phenotype was associated with increased secretion of Th17-associated CCL20, and decreased secretion of CCL2 (M2-associated) and CCL22 (Th2), as measured by multiplex bead array. In accordance, LMWH exposure to Th cells reduced the proportion of CD25highFoxp3+ regulatory T-cells, intensified IFN-γ secretion and showed a tendency to increase the lymphoblast proportions. Collectively, a mainly pro-inflammatory effect was noted on two essential tolerance-promoting cells. Although the biological significancies of these in vitro findings are uncertain and need to be confirmed in vivo, they suggest the possibility that immunological effects of LMWH may be beneficial mainly at an earlier gestational age to provide an appropriate implantation process in women with recurrent miscarriage.

Proteoglycans as Immunomodulators of the Innate Immune Response to Lung Infection

Proteoglycans (PGs) are complex, multifaceted molecules that participate in diverse interactions vital for physiological and pathological processes. As structural components, they provide a scaffold for cells and structural organization that helps define tissue architecture. Through interactions with water, PGs enable molecular and cellular movement through tissues. Through selective ionic interactions with growth factors, chemokines, cytokines, and proteases, PGs facilitate the ability of these soluble ligands to regulate intracellular signaling events and to influence the inflammatory response. In addition, recent findings now demonstrate that PGs can activate danger-associated molecular patterns (DAMPs) and other signaling pathways to influence production of many of these soluble ligands, indicating a more direct role for PGs in influencing the immune response and tissue inflammation. This review will focus on PGs that are selectively expressed during lung inflammation and will examine the novel emerging concept of PGs as immunomodulatory regulators of the innate immune responses in lungs.

The Role of Heparan Sulfate in Inflammation, and the Development of Biomimetics as Anti-Inflammatory Strategies

Key events that occur during inflammation include the recruitment, adhesion, and transmigration of leukocytes from the circulation to the site of inflammation. These events are modulated by chemokines, integrins, and selectins and the interaction of these molecules with glycosaminoglycans, predominantly heparan sulfate (HS). The development of HS/heparin mimetics that interfere or inhibit the interactions that occur between glycosaminoglycans and modulators of inflammation holds great potential for use as anti-inflammatory therapeutics. This review will detail the role of HS in the events that occur during inflammation, their interaction and modulation of inflammatory mediators, and the current advances in the development of HS/heparin mimetics as anti-inflammatory biotherapeutics.

Inhibition of Toll-Like Receptor Signaling as a Promising Therapy for Inflammatory Diseases: A Journey from Molecular to Nano Therapeutics

The recognition of invading pathogens and endogenous molecules from damaged tissues by toll-like receptors (TLRs) triggers protective self-defense mechanisms. However, excessive TLR activation disrupts the immune homeostasis by sustained pro-inflammatory cytokines and chemokines production and consequently contributes to the development of many inflammatory and autoimmune diseases, such as systemic lupus erythematosus (SLE), infection-associated sepsis, atherosclerosis, and asthma. Therefore, inhibitors/antagonists targeting TLR signals may be beneficial to treat these disorders. In this article, we first briefly summarize the pathophysiological role of TLRs in the inflammatory diseases. We then focus on reviewing the current knowledge in both preclinical and clinical studies of various TLR antagonists/inhibitors for the prevention and treatment of inflammatory diseases. These compounds range from conventional small molecules to therapeutic biologics and nanodevices. In particular, nanodevices are emerging as a new class of potent TLR inhibitors for their unique properties in desired bio-distribution, sustained circulation, and preferred pharmacodynamic and pharmacokinetic profiles. More interestingly, the inhibitory activity of these nanodevices can be regulated through precise nano-functionalization, making them the next generation therapeutics or “nano-drugs.” Although, significant efforts have been made in developing different kinds of new TLR inhibitors/antagonists, only limited numbers of them have undergone clinical trials, and none have been approved for clinical uses to date. Nevertheless, these findings and continuous studies of TLR inhibition highlight the pharmacological regulation of TLR signaling, especially on multiple TLR pathways, as future promising therapeutic strategy for various inflammatory and autoimmune diseases.

Unfractionated heparin after TBI reduces in vivo cerebrovascular inflammation, brain edema and accelerates cognitive recovery

BACKGROUND

Severe traumatic brain injury (TBI) may increase the risk of venous thromboembolic complications; however, early prevention with heparinoids is often withheld for its anticoagulant effect. New evidence suggests low molecular weight heparin reduces cerebral edema and improves neurological recovery after stroke and TBI, through blunting of cerebral leukocyte (LEU) recruitment. It remains unknown if unfractionated heparin (UFH) similarly affects brain inflammation and neurological recovery post-TBI. We hypothesized that UFH after TBI reduces cerebral edema by reducing LEU-mediated inflammation and improves neurological recovery.

METHODS

CD1 male mice underwent either TBI by controlled cortical impact (CCI) or sham craniotomy. UFH (75 U/kg or 225 U/kg) or vehicle (VEH, 0.9% saline) was administered 2, 11, 20, 27, and 34 hours after TBI. At 48 hours, pial intravital microscopy through a craniotomy was used to visualize live brain LEUs interacting with endothelium and microvascular fluorescein isothiocyanate-albumin leakage. Neurologic function (Garcia Neurological Test, GNT) and body weight loss ratios were evaluated 24 and 48 hours after TBI. Cerebral and lung wet-to-dry ratios were evaluated post mortem. ANOVA with Bonferroni correction was used to determine significance (p < 0.05).

RESULTS

Compared to positive controls (CCI), both UFH doses reduced post-TBI in vivo LEU rolling on endothelium, concurrent cerebrovascular albumin leakage, and ipsilateral cerebral water content after TBI. Additionally, only low dose UFH (75 U/kg) improved GNT at both 24 and 48 hours after TBI. High dose UFH (225 U/kg) significantly increased body weight loss above sham at 48 hours. Differences in lung water content and blood pressure between groups were not significant.

CONCLUSIONS

UFH after TBI reduces LEU recruitment, microvascular permeability, and brain edema to injured brain. Lower UFH doses concurrently improve neurological recovery whereas higher UFH may worsen functional recovery. Further study is needed to determine if this is caused by increased bleeding from injured brain with higher UFH doses.

2-O, 3-O Desulfated Heparin Blocks High Mobility Group Box 1 Release by Inhibition of p300 Acetyltransferase Activity

High mobility group box 1 (HMGB1) is an alarmin released from macrophages after infection or inflammation and is a biomarker of lung disease progression in patients with cystic fibrosis. We reported that 2-O, 3-O desulfated heparin (ODSH) inhibits the release of HMGB1 from murine macrophages triggered by neutrophil elastase both in vivo and in vitro. HMGB1 shuttles between the nucleus and the cytoplasm. When acetylated at lysine residues in the nuclear localization signal domains, HMGB1 is sequestered in the cytoplasm and is fated for secretion. In this study, we investigated the mechanism by which ODSH blocks HMGB1 secretion. We tested whether ODSH inhibits the activity of p300, a histone acetyltransferase that has been linked to HMGB1 acetylation and release. ODSH inhibited both neutrophil elastase and LPS-triggered HMGB1 release from the murine macrophage cell line RAW264.7 in a concentration-dependent manner. Fluorescein-labeled ODSH was taken up by RAW264.7 cells into the cytoplasm as well as the nucleus, suggesting an intracellular site of action of ODSH for blocking HMGB1 release. ODSH inhibited RAW264.7 cell nuclear extract, human macrophage nuclear extract, and recombinant p300 HAT activity in vitro, resulting in the failure to acetylate HMGB1. In silico molecular modeling predicted that of the numerous possible ODSH sequences, a small number preferentially recognizes a specific binding site on p300. Fluorescence binding studies showed that ODSH bound p300 tightly (dissociation constant ∼1 nM) in a highly cooperative manner. These results suggest that ODSH inhibited HMGB1 release, at least in part, by direct molecular inhibition of p300 HAT activity.

P-, but not E- or L-, selectin-mediated rolling adhesion persistence in hemodynamic flow diverges between metastatic and leukocytic cells

The ability of leukocytic cells to engage selectins via rolling adhesion is critical to inflammation, but selectins are also implicated in mediating metastatic dissemination. Using a microfluidic- and flow-based cell adhesion chromatography experimental and analytical technique, we interrogated the cell-subtype differences in engagement and sustainment of rolling adhesion on P-, E-, and L-selectin-functionalized surfaces in physiological flow. Our results indicate that, particularly at low concentrations of P-selectin, metastatic but not leukocytic cells exhibit reduced rolling adhesion persistence, whereas both cell subtypes exhibited reduced persistence on L-selectin and high persistence on E-selectin, differences not revealed by flow cytometry analysis or reflected in the extent or velocity of rolling adhesion. Conditions under which adhesion persistence was found to be significantly reduced corresponded to those exhibiting the greatest sensitivity to a selectin-antagonist. Our results suggest that potentially therapeutically exploitable differences in metastatic and leukocytic cell subtype interactions with selectins in physiological flow are identifiable through implementation of functional assays of adhesion persistence in hemodynamic flow utilizing this integrated, flow-based cell adhesion chromatography analytical technique.

The Interaction of Selectins and PSGL-1 as a Key Component in Thrombus Formation and Cancer Progression

Cellular interaction is inevitable in the pathomechanism of human disease. Formation of heterotypic cellular aggregates, between distinct cells of hematopoietic and nonhematopoietic origin, may be involved in events leading to inflammation and the complex process of cancer progression. Among adhesion receptors, the family of selectins with their ligands have been considered as one of the major contributors to cell-cell interactions. Consequently, the inhibition of the interplay between selectins and their ligands may have potential therapeutic benefits. In this review, we focus on the current evidence on the selectins as crucial modulators of inflammatory, thrombotic, and malignant disorders. Knowing that there is promiscuity in selectin binding, we outline the importance of a key protein that serves as a ligand for all selectins. This dimeric mucin, the P-selectin glycoprotein ligand 1 (PSGL-1), has emerged as a major player in inflammation, thrombus, and cancer development. We discuss the interaction of PSGL-1 with various selectins in physiological and pathological processes with particular emphasis on mechanisms that lead to severe disease.

Sulfated Alginates as Heparin Analogues: A Review of Chemical and Functional Properties

Heparin is widely recognized for its potent anticoagulating effects, but has an additional wide range of biological properties due to its high negative charge and heterogeneous molecular structure. This heterogeneity has been one of the factors in motivating the exploration of functional analogues with a more predictable modification pattern and monosaccharide sequence, that can aid in elucidating structure-function relationships and further be structurally customized to fine-tune physical and biological properties toward novel therapeutic applications and biomaterials. Alginates have been of great interest in biomedicine due to their inherent biocompatibility, gentle gelling conditions, and structural versatility from chemo-enzymatic engineering, but display limited interactions with cells and biomolecules that are characteristic of heparin and the other glycosaminoglycans (GAGs) of the extracellular environment. Here, we review the chemistry and physical and biological properties of sulfated alginates as structural and functional heparin analogues, and discuss how they may be utilized in applications where the use of heparin and other sulfated GAGs is challenging and limited.

Heparin and Heparin-Derivatives in Post-Subarachnoid Hemorrhage Brain Injury: A Multimodal Therapy for a Multimodal Disease

Pharmacologic efforts to improve outcomes following aneurysmal subarachnoid hemorrhage (aSAH) remain disappointing, likely owing to the complex nature of post-hemorrhage brain injury. Previous work suggests that heparin, due to the multimodal nature of its actions, reduces the incidence of clinical vasospasm and delayed cerebral ischemia that accompany the disease. This narrative review examines how heparin may mitigate the non-vasospastic pathological aspects of aSAH, particularly those related to neuroinflammation. Following a brief review of early brain injury in aSAH and heparin’s general pharmacology, we discuss potential mechanistic roles of heparin therapy in treating post-aSAH inflammatory injury. These roles include reducing ischemia-reperfusion injury, preventing leukocyte extravasation, modulating phagocyte activation, countering oxidative stress, and correcting blood-brain barrier dysfunction. Following a discussion of evidence to support these mechanistic roles, we provide a brief discussion of potential complications of heparin usage in aSAH. Our review suggests that heparin’s use in aSAH is not only safe, but effectively addresses a number of pathologies initiated by aSAH.

Stepwise inhibition of T cell recruitment at post-capillary venules by orally active desulfated heparins in inflammatory arthritis

Identification of the structure-function relationship of heparin, particularly between 2-O-, 6-O-, and N-sulfation and its anticoagulant or anti-inflammatory activities, is critical in order to evaluate the biological effects of heparin, especially in conjunction with modifications for oral formulation. In this study, we demonstrated that removal of 2-O, 6-O, or N-desulfation and their hydrophobic modifications have differential effects on the blocking of interactions between sLe^X and P-and L-selectins, with highest inhibition by 6-O desulfation, which was consistent with their in vivo therapeutic efficacies on CIA mice. The 6-O desulfation of lower molecular weight heparin (LMWH) retained the ability of LMWH to interfere with T cell adhesion via selectin-sLe^X interactions. Furthermore, 6DSHbD coated on the apical surface of inflamed endothelium directly blocked the adhesive interactions of circulating T cells, which was confirmed in vivo by suppressing T cell adhesion at post-capillary venular endothelium. Thus, in series with our previous study demonstrating inhibition of transendothelial migration, oral delivery of low anticoagulant LMWH to venular endothelium of inflamed joint tissues ameliorated arthritis by the stepwise inhibition of T cell recruitment and provides a rationale for the development of modified oral heparins as innovative agents for the treatment of chronic inflammatory arthritis.

The "in and out" of glucosamine 6-O-sulfation: the 6th sense of heparan sulfate

The biological properties of Heparan sulfate (HS) polysaccharides essentially rely on their ability to bind and modulate a multitude of protein ligands. These interactions involve internal oligosaccharide sequences defined by their sulfation patterns. Amongst these, the 6-O-sulfation of HS contributes significantly to the polysaccharide structural diversity and is critically involved in the binding of many proteins. HS 6-O-sulfation is catalyzed by 6-O-sulfotransferases (6OSTs) during biosynthesis, and it is further modified by the post-synthetic action of 6-O-endosulfatases (Sulfs), two enzyme families that remain poorly characterized. The aim of the present review is to summarize the contribution of 6-O-sulfates in HS structure/function relationships and to discuss the present knowledge on the complex mechanisms regulating HS 6-O-sulfation.

Heparin and LPS-induced COX-2 expression in airway cells: a link between its anti-inflammatory effects and GAG sulfation

PURPOSE/AIM

Previous studies have indicated that the sulfated polysaccharide heparin has anti-inflammatory effects. However, the mechanistic basis for these effects has not been fully elucidated.

MATERIALS AND METHODS

NCI-H292 (mucoepidermoid) and HBE-1 (normal) human bronchial epithelial cells were treated with LPS alone or in the presence of high-molecular-weight (HMW) fully sulfated heparin or desulfated HMW heparin. Cells were harvested to examine the phosphorylation levels of ERK1/2, p38, and NF-kB p65 and COX-2 protein expression by Western blot and gene expression of both COX-2 and CXCL-8 by TaqMan qRT-PCR.

RESULTS

Heparin is known to exert an influence on receptor-mediated signaling through its ability to both potentiate and inhibit the receptor-ligand interaction, depending upon its concentration. In H292 cells, fully-sulfated HMW heparin significantly reduced LPS-induced gene expression of both COX-2 and CXCL-8 for up to 48 hours, while desulfated heparin had little to no significant suppressive effect on signaling or on COX-2 gene or protein expression. Desulfated heparin, initially ineffective at preventing LPS-induced CXCL8 up-regulation, reduced CXCL8 transcription at 24 hours. In contrast, in normal HBE-1 cells, fully sulfated heparin significantly suppressed only ERK signaling, COX-2 gene expression at 12 hours, and CXCL-8 gene expression at 6 and 12 hours, while desulfated heparin had no significant effects on LPS-stimulated signaling or on gene or protein expression. Sulfation determines heparin's influence and may reflect the moderating role of GAG sulfation in lung injury and health.

CONCLUSIONS

Heparin's anti-inflammatory effects result from its nonspecific suppression of signaling and gene expression and are determined by its sulfation.

Heparin: Past, Present, and Future

Heparin, the most widely used anticoagulant drug in the world today, remains an animal-derived product with the attendant risks of adulteration and contamination. A contamination crisis in 2007-2008 increased the impetus to provide non-animal-derived sources of heparin, produced under cGMP conditions. In addition, recent studies suggest that heparin may have significant antineoplastic activity, separate and distinct from its anticoagulant activity, while other studies indicate a role for heparin in treating inflammation, infertility, and infectious disease. A variety of strategies have been proposed to produce a bioengineered heparin. In this review, we discuss several of these strategies including microbial production, mammalian cell production, and chemoenzymatic modification. We also propose strategies for creating "designer" heparins and heparan-sulfates with various biochemical and physiological properties.

Strategies to Overcome Heparins' Low Oral Bioavailability

Even after a century, heparin is still the most effective anticoagulant available with few side effects. The poor oral absorption of heparins triggered the search for strategies to achieve oral bioavailability since this route has evident advantages over parenteral administration. Several approaches emerged, such as conjugation of heparins with bile acids and lipids, formulation with penetration enhancers, and encapsulation of heparins in micro and nanoparticles. Some of these strategies appear to have potential as good delivery systems to overcome heparin’s low oral bioavailability. Nevertheless, none have reached the market yet. Overall, this review aims to provide insights regarding the oral bioavailability of heparin.

Coagulation induced by C3aR-dependent NETosis drives protumorigenic neutrophils during small intestinal tumorigenesis

Excessive activation of blood coagulation and neutrophil accumulation have been described in several human cancers. However, whether hypercoagulation and neutrophilia are linked and involved in cancer development is currently unknown. Here we show that spontaneous intestinal tumorigenesis correlates with the accumulation of low-density neutrophils with a pro-tumorigenic N2 phenotype and unprompted neutrophil extracellular traps (NET) formation. We find that increased circulating lipopolysaccharide induces upregulation of complement C3a receptor on neutrophils and activation of the complement cascade. This leads to NETosis, induction of coagulation and N2 polarization, which prompts tumorigenesis, showing a novel link between coagulation, neutrophilia and complement activation. Finally, in a cohort of patients with small but not large intestinal cancer, we find a correlation between neutrophilia and hypercoagulation. This study provides a mechanistic explanation for the tumour-promoting effects of hypercoagulation, which could be used as a new biomarker or as a therapeutic target.

It is unclear whether cancer-related hypercoagulation and neutrophilia contribute to tumorigenesis. In this study, the authors find that activation of the complement cascade causes hypercoagulation that leads to polarization of neutrophils in a mouse model of intestinal cancer, and show that blocking complement activation can reduce tumour formation.

Bioengineered heparins and heparan sulfates

Heparin and heparan sulfates are closely related linear anionic polysaccharides, called glycosaminoglycans, which exhibit a number of important biological and pharmacological activities. These polysaccharides, having complex structures and polydispersity, are biosynthesized in the Golgi of animal cells. While heparan sulfate is a widely distributed membrane and extracellular glycosaminoglycan, heparin is found primarily intracellularly in the granules of mast cells. While heparin has historically received most of the scientific attention for its anticoagulant activity, interest has steadily grown in the multi-faceted role heparan sulfate plays in normal and pathophysiology. The chemical synthesis of these glycosaminoglycans is largely precluded by their structural complexity. Today, we depend on livestock animal tissues for the isolation and the annual commercial production of hundred ton quantities of heparin used in the manufacture of anticoagulant drugs and medical device coatings. The variability of animal-sourced heparin and heparan sulfates, their inherent impurities, the limited availability of source tissues, the poor control of these source materials and their manufacturing processes, suggest a need for new approaches for their production. Over the past decade there have been major efforts in the biotechnological production of these glycosaminoglycans, driven by both therapeutic applications and as probes to study their natural functions. This review focuses on the complex biology of these glycosaminoglycans in human health and disease, and the use of recombinant technology in the chemoenzymatic synthesis and metabolic engineering of heparin and heparan sulfates.

Heparin Decreases in Tumor Necrosis Factor α (TNFα)-induced Endothelial Stress Responses Require Transmembrane Protein 184A and Induction of Dual Specificity Phosphatase 1

Despite the large number of heparin and heparan sulfate binding proteins, the molecular mechanism(s) by which heparin alters vascular cell physiology is not well understood. Studies with vascular smooth muscle cells (VSMCs) indicate a role for induction of dual specificity phosphatase 1 (DUSP1) that decreases ERK activity and results in decreased cell proliferation, which depends on specific heparin binding. The hypothesis that unfractionated heparin functions to decrease inflammatory signal transduction in endothelial cells (ECs) through heparin-induced expression of DUSP1 was tested. In addition, the expectation that the heparin response includes a decrease in cytokine-induced cytoskeletal changes was examined. Heparin pretreatment of ECs resulted in decreased TNFα-induced JNK and p38 activity and downstream target phosphorylation, as identified through Western blotting and immunofluorescence microscopy. Through knockdown strategies, the importance of heparin-induced DUSP1 expression in these effects was confirmed. Quantitative fluorescence microscopy indicated that heparin treatment of ECs reduced TNFα-induced increases in stress fibers. Monoclonal antibodies that mimic heparin-induced changes in VSMCs were employed to support the hypothesis that heparin was functioning through interactions with a receptor. Knockdown of transmembrane protein 184A (TMEM184A) confirmed its involvement in heparin-induced signaling as seen in VSMCs. Therefore, TMEM184A functions as a heparin receptor and mediates anti-inflammatory responses of ECs involving decreased JNK and p38 activity.

Interactions between nattokinase and heparin/GAGs

Nattokinase (NK) is a serine protease extracted from a traditional Japanese food called natto. Due to its strong fibrinolytic and thrombolytic activity, NK is regarded as a valuable dietary supplement or nutraceutical for the oral thrombolytic therapy. In addition, NK has been investigated for some other medical applications including treatment of hypertension, Alzheimer's disease, and vitreoretinal disorders. The most widely used clinical anticoagulants are heparin and low molecular weight heparins. The interactions between heparin and proteins modulate diverse patho-physiological processes and heparin modifies the activity of serine proteases. Indeed, heparin plays important roles in almost all of NK's potential therapeutically applications. The current report relies on surface plasmon resonance spectroscopy to examine NK interacting with heparin as well as other glycosaminoglycans (GAGs). These studies showed that NK is a heparin binding protein with an affinity of ~250 nM. Examination with differently sized heparin oligosaccharides indicated that the interaction between NK and heparin is chain-length dependent and the minimum size for heparin binding is a hexasaccharide. Studies using chemically modified heparin showed the 6-O-sulfo as well as the N-sulfo groups but not the 2-O-sulfo groups within heparin, are essential for heparin's interaction with NK. Other GAGs (including HS, DS, and CSE) displayed modest binding affinity to NK. NK also interfered with other heparin-protein interactions, including heparin's interaction with antithrombin and fibroblast growth factors.