Journal: Journal of molecular medicine (Berlin, Germany)

Article Title: Host and Pathogen Hyaluronan Signal Through Human Siglec-9 to Suppress Neutrophil Activation

doi: 10.1007/s00109-015-1341-8

Figure Lengend Snippet: Specific recognition of hyaluronan by the Ig-like-V-set domain of hSiglec-9. (a) Immobilized high molecular weight-hyaluronan (HMW-HA) was probed with human Siglec–Fc and CD44–Fc chimeras and binding evaluated by using an anti-human IgG-HRP. (b) Binding of hSiglec-9–Fc to immobilized HMW-HA was performed in the presence of increasing concentrations of HMW-HA, heparan sulfate, chondroitin sulfate or heparin. (c, d) To map the hSiglec-9 domain responsible for HA recognition, binding of hSiglec-9–Fc to immobilized HMW-HA was compared to binding of hSiglec-9–Fc with an Arg→Ala mutation in the V-set domain (hSiglec-9R120K), a fusion protein construct of the hSiglec-9 V-set domain + the second Ig-like domain (C2-set) of hSiglec-7 + human IgG Fc tail (hSiglec-9V-7C2–Fc), a fusion protein construct encompassing V-set domain of hSiglec-7 + C2-set of hSiglec-9 + human IgG Fc tail (Siglec-7V-9C2–Fc), a fusion protein construct of the hSiglec-9 V-set domain + first C2-set domain + human IgG Fc tail (Siglec-9–Fc 2D). Results are expressed as the mean ± SD. All experiments were performed in triplicate, repeated 3 times (a, d) or 2 times (b). One-way ANOVA with Dunnett’s multiple comparison test; P < 0.001 (***).

Article Snippet: Siglec-Fc proteins were purified from culture supernatant by adsorption to protein A-Sepharose (GE Healthcare); human CD44–Fc chimera was purchased from R&D Systems. hSiglecs-Fc and CD44–Fc were treated with 25 mU and 5 mU of Arthrobacter ureafaciens sialidase (AUS) for 60 min to remove Sias, prior to elution from the protein A-Sepharose.

Techniques: Molecular Weight, Binding Assay, Mutagenesis, Construct, Comparison

Journal: Journal of molecular medicine (Berlin, Germany)

Article Title: Host and Pathogen Hyaluronan Signal Through Human Siglec-9 to Suppress Neutrophil Activation

doi: 10.1007/s00109-015-1341-8

Figure Lengend Snippet: High molecular weight hyaluronan (HMW-HA) is recognized by hSiglec-9 on human neutrophils. (a) To evaluate the molecular size of hyaluronan (HA) responsible for binding to hSiglec-9, high molecular weigh HA (HMW-HA; >1,000 kDa), low molecular weigh (200 – 300 kDa-HA and 25 – 75 kDa-HA), nano-HA (nonamers) and oligo-HA (hexamers) fragments were added to compete with binding of hSiglec-9–Fc to immobilized HMW-HA plates. Binding was evaluated using an anti-human IgG-HRP. Experiment performed in triplicate and repeated 3 times; results are expressed as mean ± SD. (b) Flow cytometry reveals constitutive expression of Siglec-9 and CD44 on human neutrophils from 9 different donors; geometric mean ± 95% confidence interval. (c) Binding of FITC-labeled HMW-HA to neutrophils of these donors was evaluated by flow cytometry; geometric mean ± 95% confidence interval. (d) Human neutrophils were pretreated with anti-Siglec-9 monoclonal antibodies, anti-human CDw329 (BD Pharmingen, #550906) and anti-human Siglec-9 (R&D Systems, #BAF1139) and effects on binding to FITC-labeled HMW-HA determined. CDw329 Ab blocked binding of HMW-HA, but not GBS capsule (Fig. 5b) and was designated “α-Sig-9(HA)”; in contrast, the R&D Systems Ab blocked recognition of GBS capsule (Fig. 5b), but did not interfere with binding to HMW-HA, and was thus designated “α-Sig-9(Sia)”. Data pooled from five independent experiments in triplicate; data represent the mean ± SD. (e, f) Calcein-labeled human neutrophils were pretreated with α-Sig-9(HA), α-Sig-9(Sia) and α-CD44 mAbs, added to wells coated with immobilized HMW-HA to facilitate adherence, then unbound neutrophils washed away. Remaining neutrophils were lifted and enumerated. Experiment performed in triplicate and repeated 5 times; results are expressed as mean ± SD. One-way ANOVA with Dunnett’s multiple comparison test; P < 0.001 (***).

Article Snippet: Siglec-Fc proteins were purified from culture supernatant by adsorption to protein A-Sepharose (GE Healthcare); human CD44–Fc chimera was purchased from R&D Systems. hSiglecs-Fc and CD44–Fc were treated with 25 mU and 5 mU of Arthrobacter ureafaciens sialidase (AUS) for 60 min to remove Sias, prior to elution from the protein A-Sepharose.

Techniques: Molecular Weight, Binding Assay, Flow Cytometry, Expressing, Labeling, Comparison

Journal: Journal of molecular medicine (Berlin, Germany)

Article Title: Host and Pathogen Hyaluronan Signal Through Human Siglec-9 to Suppress Neutrophil Activation

doi: 10.1007/s00109-015-1341-8

Figure Lengend Snippet: Group A Streptococcus (GAS) engages hSiglec-9 via its surface hyaluronan capsule. (a) Human Siglec-9–Fc was immobilized to ELISA wells using protein A, and binding of FITC-labeled forms of WT GAS, its isogenic HA capsule-deficient mutant (ΔhasA), an animal-passaged hyperencapsulated (AP) derivative and its isogenic HA capsule-deficient mutant (AP ΔhasA) were evaluated; results are expressed as mean ± SD and repeated 5 times in triplicate with similar results; representative experiment shown. One-Way ANOVA with Dunnett’s multiple comparison test; P < 0.001 (***) (b) Human Siglec-9–Fc chimera was immobilized to ELISA wells via protein A in the presence of α-Sig-9(HA), α-Sig-9(Sia) or isotype control Abs and binding of FITC-labeled WT GAS or sialic acid-expressing serotype III group B Streptococcus (GBS) evaluated. (c) Human Siglec-9/9R120K/5/6/7/11 and human CD44-Fc chimera were immobilized to ELISA wells via protein A. Binding of FITC-labeled WT GAS was evaluated. Results represent mean ± SD; triplicate wells, representative experiment depicted of 5 independent repeats with similar results, performed in triplicate. (d) hSiglec-9–Fc was immobilized to ELISA plates using protein A, then wells were pretreated with HMW-HA, HMW-heparan sulfate or heparin over the indicated range of concentrations. Binding of FITC-labeled WT GAS was evaluated.

Article Snippet: Siglec-Fc proteins were purified from culture supernatant by adsorption to protein A-Sepharose (GE Healthcare); human CD44–Fc chimera was purchased from R&D Systems. hSiglecs-Fc and CD44–Fc were treated with 25 mU and 5 mU of Arthrobacter ureafaciens sialidase (AUS) for 60 min to remove Sias, prior to elution from the protein A-Sepharose.

Techniques: Enzyme-linked Immunosorbent Assay, Binding Assay, Labeling, Mutagenesis, Comparison, Expressing

Journal: Journal of molecular medicine (Berlin, Germany)

Article Title: Host and Pathogen Hyaluronan Signal Through Human Siglec-9 to Suppress Neutrophil Activation

doi: 10.1007/s00109-015-1341-8

Figure Lengend Snippet: HMW-HA binding to hSiglec-9 induces SHP-1 recruitment and blunts neutrophil NET production and oxidative burst. (a) 1.2 × 107 human neutrophils were incubated for 30 min + 10 µg/ml of high molecular weight hyaluronan (HMW-HA) + 25 nM PMA. Cell lysates were immunoprecipitated with α-Siglec9 and SHP-1 recruitment was visualized by western blot analysis; results were repeated 2 times with similar results; representative experiment with relative densitometry values is shown. (b) Neutrophils were pretreated with α-Sig-9(HA), α-Sig-9(Sia) or α-CD44 Abs, incubated with 10 µg/ml of HMW-HA and activated for 30 min with PMA. Reactive oxygen species (ROS) release was measured with the OxyBURST Green H2HFF BSA probe and results expressed as mean fluorescence intensity (MFI) ± SD; experiment repeated 5 times with similar results; representative experiment is shown. (c) Neutrophils were pretreated α-Sig-9(HA), α-Sig-9(Sia), or α-CD44 mAbs, then incubated with 10 µg/ml of HMW-HA and activated with PMA for 3 h; production of neutrophil extracellular traps (NETs) visualized by staining for DAPI (DNA, blue) + anti-myeloperoxidase/AlexaFluor488 (green); representative fields at 20x magnification is shown; experiment performed in triplicate and repeated 5 times. (d) NET production was quantified by Quant-iT™ PicoGreen® assay for extracellular DNA; results are expressed as mean ± SD; experiment repeated 3 times in triplicate with similar results; representative experiment shown. One-way ANOVA with Dunnett’s multiple comparison test; P < 0.001 (***).

Article Snippet: Siglec-Fc proteins were purified from culture supernatant by adsorption to protein A-Sepharose (GE Healthcare); human CD44–Fc chimera was purchased from R&D Systems. hSiglecs-Fc and CD44–Fc were treated with 25 mU and 5 mU of Arthrobacter ureafaciens sialidase (AUS) for 60 min to remove Sias, prior to elution from the protein A-Sepharose.

Techniques: Binding Assay, Incubation, Molecular Weight, Immunoprecipitation, Western Blot, Fluorescence, Staining, Picogreen Assay, Comparison

Journal: Journal of molecular medicine (Berlin, Germany)

Article Title: Host and Pathogen Hyaluronan Signal Through Human Siglec-9 to Suppress Neutrophil Activation

doi: 10.1007/s00109-015-1341-8

Figure Lengend Snippet: Group A Streptococcus (GAS) binding to hSiglec-9 via its surface HMW-HA capsule blunts neutrophil oxidative burst, NET responses and bactericidal activity. (a, b) Neutrophils were labeled with OxyBURST Green H2HFF BSA in the presence of α-Sig-9(HA), α-Sig-9(Sia) or α-CD44 mAbs, infected with WT or isogenic ΔhasA GAS at MOI = 20 for 30 min and oxidative burst measured by FACS; results are expressed as MFI ±SD and repeated twice with similar results; representative experiment is shown. (c) PMA-stimulated neutrophils (5 × 105 cells) were pretreated with α-Sig-9(HA), α-Sig-9(Sia), or α-CD44 mAbs and exposed for 3 h to MOI = 10 of GAS (DNase mutant) that had been pretreated or not with hyaluronidase to remove HA capsule and NET production visualized by staining for DAPI (DNA, blue) + anti-myeloperoxidase/AlexaFluor488 (green); results are repeated 5 times in triplicate, representative fields at 32 × magnification is shown. (d) NET production was quantified by Quant-iT™ PicoGreen® assay for extracellular DNA; results are expressed as mean ± SD and repeated 2 times with similar results; representative experiment shown. (e) Neutrophils were pretreated with α-Sig-9(HA), α-Sig-9(Sia) or α-CD44 mAbs, infected with WT or isogenic ΔhasA GAS at multiplicity of infection (MOI) = 10 for 30 min, then cells lysed and dilutions plated on agar for enumeration of colony forming units to evaluate neutrophil killing of GAS. Data represent the mean + SD of triplicates; repeated 4 times with similar results; representative experiment shown. One-Way ANOVA with Dunnett’s multiple comparison test; P < 0.001 (***) or P < 0.05 (*).

Article Snippet: Siglec-Fc proteins were purified from culture supernatant by adsorption to protein A-Sepharose (GE Healthcare); human CD44–Fc chimera was purchased from R&D Systems. hSiglecs-Fc and CD44–Fc were treated with 25 mU and 5 mU of Arthrobacter ureafaciens sialidase (AUS) for 60 min to remove Sias, prior to elution from the protein A-Sepharose.

Techniques: Binding Assay, Activity Assay, Labeling, Infection, Mutagenesis, Staining, Picogreen Assay, Comparison