Effect Of Dextran Sulfate Research Articles

Dextran Sulfate Inhibits Angiogenesis and Invasion of Gastric Cancer by Interfering with M2-type Macrophages Polarization.

To explore the effect of dextran sulfate (DS) on the angiogenesis, invasion, and migration of gastric cancer cells by interfering with the polarization of M2-type macrophages. The infiltration of M2-type macrophages and microvascular density in gastric cancer and paracancerous tissues were analyzed using immunohistochemistry and immunofluorescence. The effects of DS on M2-type macrophages and the angiogenesis in metastatic tumors were investigated in the nude mice intraperitoneal metastasis model using immunohistochemistry and western blot. The differentiation and polarization of macrophages, immunocytochemistry, western blot, ELISA, and transwell migration assay were used to evaluate the effect of DS on the polarization of macrophages, immunocytochemistry, western blot, ELISA, and transwell migration assay were used to evaluate the effect of DS on the polarization and recruitment capacity of macrophages. Immunocytofluorescence, tube formation assay, transwell invasion assay, wound healing assay, and western blot were used to investigate the effect of DS on the angiogenesis, invasion, and migration-promoting phenotype of M2- type macrophage in a co-culture system of macrophages and gastric cancer cells. The infiltration of M2-type macrophages and the microvascular density were highly expressed and positively correlated in the human gastric cancer tissue. DS can significantly inhibit the intraperitoneal metastases of gastric cancer in nude mice, and reduce the infiltration of M2-type macrophages and the angiogenesis in intraperitoneal metastatic tumors. Moreover, DS can prevent the polarization of M0-type macrophages to M2 type, reduce the expression of M2-type macrophage markers (CD206, CD163, IL-10, and Arg-1), down-regulate the IL-6-STAT3 pathway, and inhibit the recruitment capability of M2-type macrophages. Finally, the co-culture experiment showed that DS significantly reduced the enhancing effects of M2-type macrophages on the angiogenesis, invasion, and migration of gastric cancer cells, as well as down-regulated the related expressions of proteins (VEGF, N-cadherin, MMP-2 and Vimentin) in gastric cancer cells. DS can reduce the infiltration of M2-type macrophages and the microvascular density in intraperitoneal metastases of gastric cancer in nude mice, and inhibit the angiogenesis, invasion, and migration of gastric cancer cells by interfering with the polarization of M2-type macrophages through repression of the IL-6/STAT3 signaling pathway.

Exploring First Interactions Between Ostreid Herpesvirus 1 (OsHV-1) and Its Host, Crassostrea gigas: Effects of Specific Antiviral Antibodies and Dextran Sulfate.

Viral entry mechanisms of herpesviruses constitute a highly complex process which implicates several viral glycoproteins and different receptors on the host cell surfaces. This initial infection stage was currently undescribed for Ostreid herpes virus 1 (OsHV-1), a herpesvirus infecting bivalves including the Pacific oyster, Crassostrea gigas. To identify OsHV-1 glyproteins implicated in the attachment of the virus to oyster cells, three viral putative membrane proteins, encoded by ORF 25, 41, and 72, were selected and polyclonal antibodies against these targets were used to explore first interactions between the virus and host cells. In addition, effects of dextran sulfate, a negative charged sulfated polysaccharide, were investigated on OsHV-1 infection. Effects of antiviral antibodies and dextran sulfate were evaluated by combining viral DNA and RNA detection in spat (in vivo trials) and in oyster hemolymph (in vitro trials). Results showed that viral protein encoded by ORF 25 appeared to be involved in interaction between OsHV-1 and host cells even if other proteins are likely implicated, such as proteins encoded by ORF 72 and ORF 41. Dextran sulfate at 30 μg/mL significantly reduced the spat mortality rate in the experimental conditions. Taken together, these results contribute to better understanding the pathogenesis of the viral infection, especially during the first stage of OsHV-1 infection, and open the way toward new approaches to control OsHV-1 infection in confined facilities.

Inhibition of lysyl oxidase expression by dextran sulfate affects invasion and migration of gastric cancer cells.

In the present study, the effect of dextran sulfate (DS) on the metastasis and invasion of human gastric cancer cells and its key underlying mechanism were investigated. The levels of hypoxia-inducible factor 1α (HIF-1α), transforming growth factor β (TGF-β) and lysyl oxidase (LOX) expression were evaluated in human gastric cancer and peritumoral tissues by immunohistochemical analysis. Cell proliferation and apoptosis were also examined using the Cell Counting Kit-8 assay and flow cytometry. The effect of DS on the invasion and migration of BGC-823 cells was assessed using a Transwell assay. BGC-823 cells were divided into the control (phosphate-buffered saline-treated) and experimental (DS-treated) groups, and cultured for different times under hypoxic conditions. Subsequently, LOX and TGF-β expression levels in the cells were measured by immunocytochemistry, immunofluorescence, reverse transcription-quantitative polymerase chain reaction and western blot analysis. HIF-1α, TGF-β and LOX expression levels were significantly higher in human gastric cancer tissues as compared with that in adjacent tissues. DS influenced cell proliferation and apoptosis in a dose-dependent manner. Furthermore, DS reduced the number of invaded and migrated cells. Under hypoxic conditions, DS reduced HIF-1α, TGF-β and LOX expression levels in BGC-823 cells. After 12 h, the effect of combination of DS and β-aminopropionitrile (BAPN) on LOX and TGF-β protein levels was more significant compared with that of DS or BAPN alone. Therefore, DS may inhibit the invasion and migration of human gastric cancer cells under hypoxic conditions by influencing LOX.

Effects of dextran sulfate, 4-t-butylcyclohexanol, pongamia oil and hesperidin methyl chalcone on inflammatory and vascular responses implicated in rosacea.

BackgroundRosacea is a chronic facial skin disorder characterized by inflammation and vascular abnormalities. The pathophysiology of rosacea involves increased activation of the capsaicin receptor, TRPV1, the vascular endothelial growth factor (VEGF) pathway, and cathelicidin LL-37, MMP-9, and KLKs. We evaluated the activity of four compounds (dextran sulfate, 4-t-butylcyclohexanol [BCH; TRP-regulin®], pongamia oil, and hesperidin methyl chalcone [HMC]) on inflammatory and vascular responses implicated in rosacea.Materials and methodsThe anti-inflammatory activity of dextran sulfate was evaluated on PGE2 production after PMA stimulation of NCTC-2544 keratinocytes, and on normal human epidermal keratinocytes (NHEKs) after proinflammatory stimulation to mimic a rosacea environment. The anti-angiogenic activity of dextran sulfate was measured by analyzing pseudotube formation in co-cultured human microvascular endothelial cells/normal human dermal fibroblasts. HMC modulation of vascular responses and IL-8 cytokine production after SP stimulation was evaluated in human skin explants. We also assessed the effect of BCH on TRPV1 activation, and the effect of combined BCH and pongamia oil on the inflammatory response of NHEKs.ResultsDextran sulfate strongly and significantly inhibited PMA-induced PGE2 production, inhibited KLK5 and MMP-9 mRNA expression, and IL-8, IL-1α and VEGF production, and displayed a highly significant inhibitory effect on VEGF-induced pseudotube formation. In SP-stimulated human skin explants, HMC significantly decreased the proportion of dilated vessels, total vessel area, and IL-8 production. BCH significantly and dose-dependently inhibited TRPV1 activation, and BCH and pongamia oil inhibited CXCL1 and CXCL6 mRNA expression and IL-8 production in NHEKs. Combined BCH/pongamia oil inhibited IL-8 production synergistically.ConclusionThese in vitro results showed that dextran sulfate, BCH, pongamia oil and HMC, possess complementary soothing and anti-redness properties, supporting their combination in Avène redness-relief cosmetic products for sensitive skin prone to redness, and for topical adjunctive rosacea treatment.

Effects of dextran sulfate and gelation conditions on simvastatin encapsulation in chitosan-coated alginate microspheres

Effects of dextran sulfate and gelation conditions on simvastatin encapsulation in chitosan-coated alginate microspheres

Potential-mediated interaction between dextran sulfate and negatively charged phospholipids films at air/water and liquid/liquid interfaces

Abstract The effect of dextran sulfate (DS) on distearoyl phosphatidyl glycerol (DSPG) and distearoyl phosphatidic acid (DSPA) films formed in the presence of Ca2Cl, LiCl or KCl as aqueous electrolytes, was analyzed by cyclic voltammetry, surface pressure-area and surface potential-area isotherms and Brewster angle microscopy. Experiments of cyclic voltammetry at the water/1,2-dichloroethane interface showed an interfacial adsorption/desorption process in the presence of DSPG, or DSPA, DS and LiCl. It is suggested that this process could correspond to the formation of an interfacial complex DS–Li+–DSPG or DS–Li+–DSPA at positive potentials with respect to the potential of zero charge (pzc) and its desorption from the interface towards the aqueous phase, by complex dissociation, at potentials below pzc. The voltammetric analysis of tetraethylammonium (TEA+) cation transfer, from the aqueous to the organic phase, evidenced a blocking effect of DSPG and DSPA films on that process, whose magnitude depends on both the nature of the phospholipids and the cation forming the aqueous electrolyte. The structure and permeability of those films were altered by the presence of DS, by formation of the complex DS–cation–phospholipid, which produces an expansion of the monolayer, whose extent depends on the cation present in water, and the polar head group of the phospholipid. Electrochemical experiments were completed with compression isotherms for DSPG and DSPA monolayers both in the absence and in the presence of DS. In this case, as opposed to the voltammetric results, a negligible effect of DS was observed in the isotherms. This apparent contradiction could be explained considering the effect of polarization, which enables the accumulation of cations at the interface, favouring the formation of the DS–cation–phospholipid complex which is responsible for the increase in the film permeability. Similarly, the thickness values for phospholipid films obtained from the Brewster angle microscopy experiments were the same either in the absence or in the presence of DS at any lateral pressure value, which is a direct evidence of lack of interaction between DS and DSPA or DSPG molecules at open circuit. Therefore, it was concluded that the formation of the complex DS–cation–phosholipid, responsible for the increase in permeability observed in voltammetric experiments, must be attributed to the polarization of the interface. The application of high positive potentials at the interface promotes cations accumulation, which neutralize the negative charge in phosphate groups and in DS and allows their interaction.

Dextran sulfate inhibits staurosporine-induced apoptosis in Chinese hamster ovary (CHO) cells: Involvement of the mitochondrial pathway

Dextran sulfate has been reported to reduce cell aggregation and increase culture viability in suspension cultures of CHO cells. However, only a few of these reports have focused on the effects of dextran sulfate at the cellular level, especially with respect to cell viability. The goal of this study was to examine whether dextran sulfate inhibits CHO cell death through interference with the cellular apoptotic pathway. Apoptosis was induced using staurosporine, and the addition of dextran sulfate was shown to prevent apoptosis, as evident by a reduction in DNA laddering. Dextran sulfate also affected other events in the apoptotic pathway following the addition of staurosporine. Specifically, dextran sulfate decreased pro-caspase-9 activation, cleaved caspase-3 levels, cytochrome c release into the cytosol and mitochondrial transmembrane potential collapse. This data indicates that the mechanism by which dextran sulfate decreases staurosporine-induced apoptosis involves the mitochondrial pathway as early as cytochrome c release, but without caspase-8 activation. This study advances the understanding of the anti-apoptotic action of dextran sulfate on CHO cells and provides a rationale for the application of dextran sulfate in CHO cell culture processes.

Effects of dextran sulfate on pulmonary radiation injury--clinical and experimental studies (author's transl)

Effects of dextran sulfate on pulmonary radiation injury--clinical and experimental studies (author's transl)

Modulation of the proteolytic activity of the complement protease C1s by polyanions: implications for polyanion-mediated acceleration of interaction between C1s and SERPING1

The complement system plays crucial roles in the immune system, but incorrect regulation causes inflammation and targeting of self-tissue, leading to diseases such as systemic lupus erythematosus, rheumatoid arthritis and age-related macular degeneration. In vivo, the initiating complexes of the classical complement and lectin pathways are controlled by SERPING1 [(C1 inhibitor) serpin peptidase inhibitor, clade G, member 1], which inactivates the components C1s and MASP-2 (mannan-binding lectin serine peptidase 2). GAGs (glycosaminoglycan) and DXS (dextran sulfate) are able to significantly accelerate SERPING1-mediated inactivation of C1s, the key effector enzyme of the classical C1 complex, although the mechanism is poorly understood. In the present study we have shown that C1s can bind to DXS and heparin and that these polyanions enhanced C1s proteolytic activity at low concentrations and inhibited it at higher concentrations. The recent determination of the crystal structure of SERPING1 has given rise to the hypothesis that both the serpin (serine protease inhibitor)-polyanion and protease-polyanion interactions might be required to accelerate the association rate of SERPING1 and C1s. To determine what proportion of the acceleration was due to protease-polyanion interactions, a chimaeric mutant of alpha1-antitrypsin containing the P4-P1 residues from the SERPING1 RCL (reactive-centre loop) was produced. Like SERPING1, this molecule is able to effectively inhibit C1s, but is unable to bind polyanions. DXS exerted a biphasic effect on the association rate of C1s which correlated strongly with the effect of DXS on C1s proteolytic activity. Thus, whereas polyanions are able to bind C1s and modulate its activity, polyanion interactions with SERPING1 must also play a vital role in the mechanism by which these cofactors accelerate the C1s-SERPING1 reaction.

Glycosaminoglycans Facilitate Procathepsin B Activation through Disruption of Propeptide-Mature Enzyme Interactions

Lysosomal cysteine cathepsin B participates in numerous diverse cellular processes. In acquiring its activity, the proregion, which blocks the substrate-binding site in the proenzyme, needs to be cleaved off. Here we demonstrate that polyanionic polysaccharides, glycosaminoglycans (GAGs), can accelerate the autocatalytic removal of the propeptide and subsequent activation of cathepsin B. We show that naturally occurring GAGs such as chondroitin sulfates and heparin, as well as the synthetic analog dextran sulfate, accelerate the processing in a concentration-dependent manner. Heparin oligosaccharides down to the size of tetrasaccharides were efficient in accelerating the procathepsin B processing, whereas disaccharides were without effect. Further, the ability of the GAGs to accelerate procathepsin B processing was sensitive to increasing NaCl concentrations, indicating that electrostatic interaction between the GAGs and procathepsin B are operative in the accelerating effect. Also the processing of the catalytic procathepsin B mutant by wild type cathepsin B was enhanced in the presence of GAGs, suggesting that GAGs induce a conformational change in procathepsin B, converting it into a better substrate. Site-directed mutagenesis showed that His(28), Lys(39), and Arg(40), located within the procathepsin B propeptide, have significant roles in the acceleration of procathepsin B activation induced by short GAGs. Because procathepsin B and GAGs often co-localize in vivo, we propose that GAGs may play a physiological role in the activation of procathepsin B.

Effects of dextran sulfate, NaCl, and initial protein concentration on thermal stability of β-lactoglobulin and α-lactalbumin at neutral pH

The effects of NaCl, dextran sulfate (DS), and initial protein concentration on thermal stability of β-lactoglobulin ( β-LG) and α-lactalbumin ( α-LA) at pH 6.8 were investigated. NaCl was the biggest factor in accelerating protein aggregation as shown by an increase in turbidity, molecular size, and a decrease in protein solubility. DS at low concentration showed a protective effect against aggregation. Evidence suggested some degree of interaction between β-LG and DS. At higher concentration, phase separation between biopolymers favored aggregation, which resulted in an increase in turbidity and a reduction in protein solubility.

How does dextran sulfate prevent heat induced aggregation of protein?: The mechanism and its limitation as aggregation inhibitor

The effect of dextran sulfate on protein aggregation was investigated to provide the clues of its biochemical mechanism. The interaction between dextran sulfate and BSA varied with the pH values of the solution, which led to the different extent of aggregation prevention by dextran sulfate. Light scattering data with thermal scan showed that dextran sulfate suppressed BSA aggregation at pH 5.1 and pH 6.2, while it had no effect at pH 7.5. Isothermal titration calorimetric analysis suggested that the pH dependency of the role of dextran sulfate on BSA aggregation would be related to the difference in the mode of BSA–dextran sulfate complex formation. Isothermal titration calorimetric analysis at pH 6.2 indicated that dextran sulfate did not bind to native BSA at this pH, but interacted with partially unfolded BSA. While stabilizing native form of protein by the complex formation has been suggested as the suitable mechanism of preventing aggregation, our observation of conformational changes by circular dichroism spectroscopy showed that strong electrostatic interaction between dextran sulfate and BSA rather facilitated the denaturation of BSA. Combining the data from isothermal titration calorimetry, circular dichroism, and dynamic light scattering, we found that the complex formation of the intermediate state of denatured BSA with dextran sulfate is a prerequisite to suppress the aggregation by preventing further oligomerization/aggregation process of denatured protein.

Electrochemical microfluidic biosensor for the detection of nucleic acid sequences

A microfluidic biosensor with electrochemical detection for the quantification of nucleic acid sequences was developed. In contrast to most microbiosensors that are based on fluorescence for signal generation, it takes advantage of the simplicity and high sensitivity provided by an amperometric and coulorimetric detection system. An interdigitated ultramicroelectrode array (IDUA) was fabricated in a glass chip and integrated directly with microchannels made of poly(dimethylsiloxane) (PDMS). The assembly was packaged into a Plexiglas housing providing fluid and electrical connections. IDUAs were characterized amperometrically and using cyclic voltammetry with respect to static and dynamic responses for the presence of a reversible redox couple-potassium hexacyanoferrate (ii)/hexacyanoferrate (iii) (ferri/ferrocyanide). A combined concentration of 0.5 microM of ferro/ferricyanide was determined as lower limit of detection with a dynamic range of 5 orders of magnitude. Background signals were negligible and the IDUA responded in a highly reversible manner to the injection of various volumes and various concentrations of the electrochemical marker. For the detection of nucleic acid sequences, liposomes entrapping the electrochemical marker were tagged with a DNA probe, and superparamagnetic beads were coated with a second DNA probe. A single stranded DNA target sequence hybridized with both probes. The sandwich was captured in the microfluidic channel just upstream of the IDUA via a magnet located in the outside housing. Liposomes were lysed using a detergent and the amount of released ferro/ferricyanide was quantified while passing by the IDUA. Optimal location of the magnet with respect to the IDUA was investigated, the effect of dextran sulfate on the hybridization reaction was studied and the amount of magnetic beads used in the assay was optimized. A dose response curve using varying concentrations of target DNA molecules was carried out demonstrating a limit of detection at 1 fmol assay(-1) and a dynamic range between 1 and 50 fmol. The overall assay took 6 min to complete, plus 15-20 min of pre-incubation and required only a simple potentiostat for signal recording and interpretation.

Dextran sulfate as a leukocyte-endothelium adhesion molecule inhibitor of lung injury in pediatric open-heart surgery

In spite of the progress in operative techniques and pre- and postoperative management for congenital heart disease, lung injury induced by the extracorporeal circulation is still a serious insult in pediatric open-heart operations. To prevent this injury, we used a leukocyte-endothelial cell adhesion molecule blocking agent, dextran sulfate, in a clinical setting. Sixty mg/kg of dextran sulfate (DS) was intravenously infused to the patients just before cardiopulmonary bypass was started and 600 mg was added to the bypass circuit prime. Thirty patients (DS group, 14 patients with atrial septal defect, and 16 patients with ventricular septal defect) were compared with age and body-weight matched control patients (control group, 14 patients with atrial septal defect, 11 patients with ventricular septal defect). Postoperative respiratory index, white blood cell counts, complement C3 and plasma granulocyte elastase levels during and after the operation were measured. Respiratory index just after the termination of cardiopulmonary bypass was better preserved in the DS group than in the control group (0.50 +/- 0.08 versus 0.81 +/- 0.12, p < 0.01). The sum total amount of measured granulocyte elastase across whole study period was significantly lower in the DS group (p < 0.05). The data suggeste the possible effects of dextran sulfate in ameliorating post-perfusion lung damage by interfering with leukocyte-endothelial cell adhesion in pediatric open-heart operations. Future application to patients with more complex anomalies is anticipated.

Differential scanning calorimetry study of pressure/temperature processed β-lactoglobulin: The effect of dextran sulphate

β-Lactoglobulin at pH 7 in the presence or absence of dextran sulphate (1:1 weight ratio) was subjected to a combined pressure and temperature treatment (pressures up to 280 MPa, temperature up to 60 °C and time up to 30 min). The effect of the treatment was assessed post-processing using differential scanning calorimetry. The thermograms in absence of dextran sulphate were very broad with possibly a shoulder on the low temperature side and showed a decrease in calorimetric enthalpy as the intensity of treatment increased. In the presence of dextran sulphate the thermograms had a much sharper shape. The calorimetric enthalpy was reduced further than in the absence of dextran sulphate. This demonstrated that the polysaccharide sensitised the protein to the combined treatment. Treatment with pressure and temperature alone demonstrated that dextran sulphate sensitised the protein structure to pressure. The species created by the combined process could be in the molten globule state and possess improved functional properties. Also the operating parameters applied could potentially be conditions for improved functionality.

Dextran sulfate as a material for the preparation of a membrane for immunoisolation

Bioartificial pancreas, in which the islets of Langerhans (islets) are enclosed in an artificial membrane to be protected from the host immune system, is expected to be a promising medical device to treat patients who suffer from insulin-dependent diabetes. Our strategy for preparation of a bioartificial pancreas involves utilizing a membrane including polymeric materials that can inhibit the complement. In our series of studies, we have examined interactions of various polyanions with the complement system to search for potential complement inhibitors. In this study, we concentrated our efforts to clarify the effects of dextran sulfate on the complement system. All of the dextran sulfates examined inhibited the complement activation through both classical and alternative pathways as previously reported. In addition to their inhibitory effects, a certain species of dextran sulfate (molecular mass 10 kDa, degree of sulfonation in a pyranose ring 1.99) specifically degraded C3 without complement activation and, thus, anaphylatoxins that trigger inflammatory reactions were not generated. These facts suggest that a membrane including dextran sulfate effectively protects the islet cells from humoral immunity in addition to not triggering inflammatory reactions. These properties of the membrane make it suitable for a bioratificial pancreas.

An ecto-ATPase activity present in Leishmania tropica stimulated by dextran sulfate.

In this study we report the effects of sulfated polysaccharides on the ecto-ATPase activity of intact cells of Leishmania tropica. Increasing concentrations of dextran sulfate stimulated progressively the ecto-ATPase activity, but did not modify other ecto-enzymes present on the surface of this parasite, such as 5'nucleotidase, 3'nucleotidase and a membrane-bound acid phosphatase activity. This stimulation was not observed when other sulfated polysaccharides such as chondroitin sulfates and heparin were tested. It depends on size and charge of the dextran sulfated molecule. When the cells were incubated in the presence of dextran sulfate Mr 8,000; 40,000 and 500,000 the stimulation of the ecto-ATPase activity was 11%; 23%; and 63%, respectively, and the stimulation was not observed when desulfated dextran (Mr 40,000) was used. The effects of dextran sulfate also depend on pH of the medium. At pH 7.5, the stimulation was over 60%, whereas at pH 8.5 only 25%. The effects of dextran sulfate 500,000 on the ecto-ATPase activity was totally abolished by spermidine and partially by putrescine, two polyamines synthesized and released by Leishmania.

Effects of dextran sulfate on tracheal mucociliary velocity in dogs.

We have shown that low molecular weight dextran, as a potential mucolytic agent, reduced the viscoelasticity and spinnability of cystic fibrosis (CF) sputum and improved its ciliary transportability in vitro; it also reduced viscoelasticity of healthy dog mucus in in vitro testing. In anesthetized dogs, dextran administered by aerosol at 65 mg/mL increased tracheal mucus velocity, but this increase was not sustained for higher concentrations. The purpose of the present study is to evaluate whether low mol. wt. dextran sulfate, a charged oligosaccharide, exhibits similar effects to previously tested neutral dextran when administered by aerosol to anesthetized dogs in terms of mucus rheology and mucociliary clearance rate. Healthy mongrel dogs were anesthetized with pentobarbital and intubated. Aerosols of Ringer's solution or dextran sulfate (m.w. 5000) dissolved in Ringer's were generated by Pari LC STAR nebulizer, and delivered during 30-min periods of spontaneous breathing. Tracheal transepithelial potential difference (PD, using agar filled electrodes) and tracheal mucociliary velocity (TMV, by charcoal marker particle transport) were measured under bronchoscopic control, and mucus for viscoelasticity analysis by magnetic rheometry was collected by the endotracheal tube method. We performed experiments in seven dogs, involving 30-min administrations of aerosol, separated by 30-min periods of no aerosol. All dogs received inhalations of 6.5 mg/mL, 20 mg/mL, and 65 mg/mL dextran sulfate. Tracheal mucus viscoelasticity (average log G* over 1-100 rad/s) decreased progressively with increasing dose of dextran sulfate; for the highest concentration (65 mg/mL), log G* decreased by a factor of 2.61 (p = 0.021). A modest increase in the TMV was observed for the first dose of dextran sulfate (128% of baseline at 6.5 mg/mL, p = 0.066); thereafter TMV was stable. PD increased significantly at each concentration of dextran sulfate compared with Ringer control; however, there was no additional change between the three groups. The solids content of collected airway fluid (%SC) was gradually increased during successive 30-min dextran sulfate aerosols, indicating a significant residence time for the dextran in the mucus, and correlating with the decrease in viscoelasticity. These results suggest that dextran sulfate may be potentially of therapeutic value as a mucolytic agent, assisting mucus clearance by cough and physiotherapy, although whether it stimulates mucociliary clearance remains to be proven.

Single basic amino acid substitutions at position 302 or 320 in the V3 domain of HIV type 1 are not sufficient to alter the antiviral activity of dextran sulfate and heparin.

The third variable domain (V3 domain) of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 contains a substantial number of positively charged amino acid residues. We previously demonstrated that mutation of basic amino acid residues at position 303, 306, 309, 313, and 325 in the V3 domain of HIV-1 strain NL4-3 resulted in a dramatic elimination of both virus infectivity and syncytium-inducing ability. Mutations of arginine at position 302 to serine (R302S) or lysine at position 320 to glutamine (K320Q) had variable effects on infectivity for a panel of T cell lines tested. These mutations are located on opposite sides of the Gly-Pro-Gly-Arg-Ala sequence in the center of the V3 domain. The R302S and K320Q mutations allowed us to determine if these basic residues are important for virus neutralization by polyanionic compounds. Dextran sulfate and heparin inhibited the cytopathogenicities of both mutants for MT-4 cells, although their 50% antiviral effective doses were slightly higher than those required to achieve complete protection against wild-type HIV-1NL4-3 replication. This result emphasizes that the basic amino acids of Arg302 and Lys320 are not essential for the inhibitory effect of dextran sulfate and heparin on HIV-1 infection.

Influence of host cell type and V3 loop of the surface glycoprotein on susceptibility of human immunodeficiency virus type 1 to polyanion compounds

Dextran sulfate is a potent inhibitor of human immunodeficiency virus (HIV) binding and replication in lymphocytic cell lines. In this study, we demonstrate that the effect of dextran sulfate and heparin depends on the host cell type and on the V3 loop, the principal neutralizing determinant of HIV gp120. In particular, when dextran sulfate was tested on primary human macrophages infected with macrophage-tropic viruses, enhancement of infection was observed in 6 of 11 independent macrophage preparations and with 5 of 13 primary HIV isolates. Our in vitro observations might explain why enhanced HIV replication was observed in HIV-infected patients treated with dextran sulfate.