Journal: EMBO Molecular Medicine

Article Title: Enhancing protective microglial activities with a dual function TREM 2 antibody to the stalk region

doi: 10.15252/emmm.201911227

Figure Lengend Snippet: Schematic representation of TREM2 processing by ADAM10/17. Cleavage occurs C‐terminal of residue His 157. The entire ectodomain (residues 19–171) was used for immunization of rats to generate TREM2 antibodies. CTF, C‐terminal fragment; sTREM2, soluble TREM2. Immunoblot analysis of membrane fractions of HEK293 Flp‐In cells stably overexpressing both mouse TREM2 and mouse DAP12 upon treatment with 4D9 antibody reveals increased levels of membrane‐bound TREM2 similar to what can be achieved by ADAM protease inhibition using the GM6001 inhibitor. An isotype antibody was used as a negative control. Calnexin served as a loading control. Levels of membrane‐bound TREM2 were quantified by MSD ELISA. Data represent the mean ± SEM ( n = 3). One‐way ANOVA, Tukey's post hoc test; P (DMSO vs GM) = 0.0011; P (DMSO vs isotype) = 0.992; P (isotype vs 4D9) = 0.0005; n.s., not significant. Immunoblot analysis of conditioned media from HEK293 Flp‐In cells stably overexpressing both mouse TREM2 and mouse DAP12 upon treatment with 4D9 antibody reveals decreased levels of sTREM2 similar to what can be achieved by ADAM protease inhibition using the GM6001 inhibitor. An isotype antibody was used as a negative control. sAPPα served as a loading control. Note that heavy and light chains of the antibodies used for treatment are also detected and annotated. Levels of sTREM2 were quantified by MSD ELISA. Data represent the mean ± SEM ( n = 3). One‐way ANOVA, Tukey's post hoc test; P (DMSO vs GM) < 0.0001; P (DMSO vs isotype) = 0.6372; P (isotype vs 4D9) < 0.0001; n.s., not significant. 4D9 antibody selectively detects TREM2 on the cell surface of HEK293 Flp‐In cells stably overexpressing mouse TREM2 and mouse DAP12. An anti‐HA antibody was used as a positive control, while empty vector‐transfected HEK293 Flp‐In cells were used as a negative control. Scale bar = 10 μm. Peptide ELISAs detect anti‐mouse TREM2 antibody binding to tiled stalk region peptides, full‐length stalk peptide, or a truncated ADAM cleavage site peptide. The binding epitope of 4D9 antibody is located 12‐amino acids N‐terminal of the ADAM cleavage site at His 157. Sequence comparison of mouse TREM2 and human TREM2 shows substantial sequence conservation around the 4D9 epitope (upper panel). Immunoblot analysis demonstrates that antibody 4D9 is highly specific for mouse TREM2 and does not detect human TREM2 or mouse TREM1 (lower panel). 4D9 binding to the mouse TREM2 ECD is competed off by a stalk region peptide. A competition ELISA demonstrates that a dose titration of stalk peptide reduces binding of 4D9 to TREM2 ECD with an EC50 of 1.3 μM. Data represent the mean ± SEM ( n = 3). ECD, extracellular domain. Surface plasmon resonance binding kinetics of increasing concentrations of 4D9 antibody to mouse TREM2 ECD evaluated by Biacore, k on = 5.9 × 10 5 M −1 s −1 , k off = 4.0 × 10 −5 s −1 , K D = 68 pM. 4D9 binding to human TREM2 or mouse TREM1 was undetectable. Data information: Statistical evaluations are displayed as follows: ** P < 0.01; *** P < 0.001; **** P < 0.0001. Source data are available online for this figure.

Article Snippet: For immunoblotting of 10 ng human TREM2‐(His) 6 (Sino Biological) and 10 ng mouse TREM1‐Fc (R&D Systems), AF1828 and AF1187 antibodies (both R&D Systems) were used, respectively.

Techniques: Residue, Western Blot, Membrane, Stable Transfection, Inhibition, Negative Control, Enzyme-linked Immunosorbent Assay, Positive Control, Plasmid Preparation, Transfection, Binding Assay, Sequencing, Comparison, Titration, SPR Assay

Journal: bioRxiv

Article Title: Extracellular CIRP as a Novel Endogenous TREM-1 Ligand to Fuel Inflammation

doi: 10.1101/674218

Figure Lengend Snippet: (A) SPR between rmCIRP and rmTREM-1. Anti-his Ab was used to capture rmCIRP-his. rmTREM-1 was injected as an analyte in concentrations of 0 to 500 nM. (B) 1.5 × 10 4 RAW264.7 cells were treated with rmCIRP (5 μg/ml) at 4°C for 10 min, fixed in a nonpermeabilized fashion, and stained with rabbit anti-mouse CIRP Ab, goat anti-mouse TREM-1 Ab, goat anti-CD11b Ab, Cy5-conjugated AffiniPure donkey anti-goat IgG, and Cy3-conjugated AffiniPure F(ab’)2 fragment donkey anti-rabbit IgG. Confocal microscopy images were obtained at using a Zeiss LSM880 confocal microscope equipped with a 63× objective. Images were analyzed and quantified by using the ZenBlue software. ( C) After the staining protocol described in (B) , cell associated fluorescence was measured on Biotek Synergy Neo2 at 566 nm upon excitation at 488 nm ( E 1), at 681 nm after excitation at 630 nm ( E 2), and at 681 nm after excitation at 488 nm ( E 3). The transfer of fluorescence was calculated as FRET units. FRET unit = [ E 3 both − E 3 none ] − [( E 3 Cy5 − E 3 none ) × ( E 2 both / E 2 Cy5 )] − [( E 3 Cy3 − E 3 none ) × ( E 1 both / E 1 Cy3 )]. Data are expressed as means ± SE obtained from three independent experiments, n=9/group. Groups compared by unpaired t-test (*p<0.01 vs. CD11b). (D) A total of 1 × 10 6 /ml RAW264.7 cells were stimulated with rmCIRP (1 µg/ml) for various times. Extracted proteins were immunoprecipitated by using anti-DAP12 Ab, followed by Western blotting using pTyr (4G10) and DAP12 Ab. Extracted proteins obtained from rmCIRP (1 µg/ml for various times) stimulated RAW264.7 cells (1 × 10 6 /ml) were subjected to Western blotting using pSyk, Syk, and β–actin Abs. Representative western blots for phosphotyrosine (4G10), DAP12, pSyk, Syk, and β–actin are shown. (E, F) Each blot was quantified by densitometric analysis. Phosphotyrosine (pDAP12) and pSyk expression in each sample was normalized to DAP12 or Syk or β-actin expression and the mean values of 0 min of rmCIRP-treated groups were standardized as one for comparison. Data are expressed as means ± SE (n=6 samples/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. rmCIRP at 0 min). (G) RAW264.7 cells were transfected with TREM-1 siRNA, control siRNA, underwent mock transfection, or no transfection. Cells were then stimulated with PBS control or 1μg/ml rmCIRP. After 6 h, TNF-α in the supernatant was analyzed by ELISA. Data are expressed as means ± SE (n=3 samples/group). Multiple groups were compared by one-way ANOVA and Tukey method (*p<0.05 vs. respective PBS group; # p<0.01 vs. rmCIRP-treated non-transfected cells). (H) RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and stimulated with PBS or rmCIRP (1 µg/ml). Simultaneously cells were treated with various doses of LP-17 or LP-17-Sc1. After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE obtained from five independent experiments (n=3-10 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. PBS; #p<0.05 vs. rmCIRP+PBS). FRET, fluorescence resonance energy transfer; TNF, tumor necrosis factor; DAP12, DNAX activation protein of 12kDa; ELISA, enzyme-linked immunosorbent assay; PBS phosphate buffered saline.

Article Snippet: Antibodies used were as follows: rabbit anti-mouse CIRP Ab (Catalog 10209-2-AP; ProteinTech, Rosemont, IL), goat anti-mouse TREM-1 Ab (Catalog AF1187; R&D Systems), goat anti-CD11b Ab (Catalog MBS420973MyBioSource, San Diego, CA), Cy5-conjugated AffiniPure donkey anti-goat IgG (Code 705-175-147; Jackson ImmunoResearch Laboratories, West Grove, PA) and Cy3-conjugated AffiniPure F(ab’)2 fragment donkey anti-rabbit IgG (Code 711-166-152; Jackson ImmunoResearch Laboratories).

Techniques: Injection, Staining, Confocal Microscopy, Microscopy, Software, Fluorescence, Immunoprecipitation, Western Blot, Expressing, Comparison, Transfection, Enzyme-linked Immunosorbent Assay, Förster Resonance Energy Transfer, Activation Assay, Saline

Journal: bioRxiv

Article Title: Extracellular CIRP as a Novel Endogenous TREM-1 Ligand to Fuel Inflammation

doi: 10.1101/674218

Figure Lengend Snippet: (A) Partial amino acid sequence of murine CIRP highlighting an area of similarity between murine PGLYRP1. Three peptides (M1, M2, and M3) are highlighted from within the CIRP sequence. RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and treated with 10 µg/ml of peptides M1, M2, or M3 for 30 min. Cells were then stimulated with rmCIRP (1 µg/ml). After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE obtained from two independent experiments (n=6 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. unstimulated cells and #p<0.05 vs. rmCIRP-treated cells). (B) SPR between rmTREM-1 and M3. M3 was injected as an analyte in concentrations of 0 to 20 μM. (C) RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and treated with M3 or M3-Sc1 at a dose of 10 µg/ml for 30 min. Cells were then stimulated with PBS or rmCIRP (5 µg/ml) at 4°C for 10 min, fixed in a nonpermeabilized fashion, and stained as described in 1B. FRET analysis was performed as described in 1B. Data are expressed as means ± SE obtained from three independent experiments, n=9/group. Multiple groups were compared by one-way ANOVA and Tukey method (*p<0.05 vs CD11b + rmCIRP, #p<0.05 vs TREM-1 + rmCIRP). (D) To activate RAW264.7 cells through TREM-1, 96-well flat bottom plates were pre-coated with 20 μg/ml of an agonist anti-TREM-1 mAb overnight at 37°C. The wells were washed with sterile PBS and 5 × 10 4 cells/well were plated. Prior to plating, cells were premixed with either PBS control, M3 (10 μg/ml) or scramble M3-Sc1 (10 μg/ml) for 30 min. After plating, TNF-α production was measured in the culture supernatants after an additional 24 h of incubation. Data are expressed as means ± SE. The experiment was performed two independent times with n=5 wells per group. Multiple groups were compared by one-way ANOVA and Tukey method (*p<0.05 vs. uncoated; #p<0.05 vs. TREM-1 Ab + PBS). (E) RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and treated with various doses of M3, M3-Sc1, or M3-Sc1 for 30 min. Cells were then stimulated with PBS or rmCIRP (1 µg/ml). After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE obtained from three independent experiments (n=4 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. PBS-treated cells; #p<0.05 vs. rmCIRP + PBS). (F) Macrophages from healthy human donors (1×10 4 cells/ml) were plated in 96-well culture plate and treated with various doses of M3 for 30 minutes. Cells were then stimulated with PBS or rmCIRP (1 µg/ml). After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE (n=5 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. PBS-treated cells; #p<0.05 vs. rmCIRP + PBS). FRET, fluorescence resonance energy transfer; TNF, tumor necrosis factor; ELISA, enzyme-linked immunosorbent assay; PBS, phosphate buffered saline; PGLYRP1, peptidoglycan recognition protein 1.

Article Snippet: Antibodies used were as follows: rabbit anti-mouse CIRP Ab (Catalog 10209-2-AP; ProteinTech, Rosemont, IL), goat anti-mouse TREM-1 Ab (Catalog AF1187; R&D Systems), goat anti-CD11b Ab (Catalog MBS420973MyBioSource, San Diego, CA), Cy5-conjugated AffiniPure donkey anti-goat IgG (Code 705-175-147; Jackson ImmunoResearch Laboratories, West Grove, PA) and Cy3-conjugated AffiniPure F(ab’)2 fragment donkey anti-rabbit IgG (Code 711-166-152; Jackson ImmunoResearch Laboratories).

Techniques: Sequencing, Enzyme-linked Immunosorbent Assay, Injection, Staining, Sterility, Incubation, Fluorescence, Förster Resonance Energy Transfer, Saline

Journal: bioRxiv

Article Title: Extracellular CIRP as a Novel Endogenous TREM-1 Ligand to Fuel Inflammation

doi: 10.1101/674218

Figure Lengend Snippet: Sepsis and I/R causes an increased release of eCIRP. As the endogenous ligand eCIRP recognizes TREM-1 and activates intracellular signaling molecules DAP12 and Syk, leading to increased expression of pro-inflammatory mediators that cause excessive inflammation and remote tissue injury. eCIRP increases TREM-1 expression, possibly via positive feedback induction. A small peptide M3 derived from human eCIRP abrogates eCIRP-TREM-1 interaction, thereby leading to decreased inflammation and attenuated ALI. I/R, ischemia and reperfusion; DAP12, DNAX activation protein of 12kDa; ALI, acute lung injury.

Article Snippet: Antibodies used were as follows: rabbit anti-mouse CIRP Ab (Catalog 10209-2-AP; ProteinTech, Rosemont, IL), goat anti-mouse TREM-1 Ab (Catalog AF1187; R&D Systems), goat anti-CD11b Ab (Catalog MBS420973MyBioSource, San Diego, CA), Cy5-conjugated AffiniPure donkey anti-goat IgG (Code 705-175-147; Jackson ImmunoResearch Laboratories, West Grove, PA) and Cy3-conjugated AffiniPure F(ab’)2 fragment donkey anti-rabbit IgG (Code 711-166-152; Jackson ImmunoResearch Laboratories).

Techniques: Expressing, Derivative Assay, Activation Assay

Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine

Article Title: Tracking Innate Immune Activation in a Mouse Model of Parkinson's Disease Using TREM1 and TSPO PET Tracers.

doi: 10.2967/jnumed.121.263039

Figure Lengend Snippet: FIGURE 5. Representative 64Cu-TREM1 PET/CT whole-body maximum-intensity-projection images, coronal brain images, and autoradiography of 40-mm-thick coronal mouse brain sections. Dashed out- lines indicate spleen and coronal brain sections. %ID 5 percentage injected dose; ARG 5 autoradio- graphy; C 5 contralateral brain hemisphere; I 5 ipsilateral brain hemisphere; KO 5 knockout; MIP 5 maximum-intensity projection; OHDA 5 hydroxydopamine.

Article Snippet: Mouse TREM1 mAb (R&D Systems) was conjugated with DOTAN-hydroxysuccinimide (Macrocyclics) using metal-free buffers and previously published procedures (25,32).

Techniques: Positron Emission Tomography-Computed Tomography, Autoradiography, Injection, Knock-Out

Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine

Article Title: Tracking Innate Immune Activation in a Mouse Model of Parkinson's Disease Using TREM1 and TSPO PET Tracers.

doi: 10.2967/jnumed.121.263039

Figure Lengend Snippet: FIGURE 6. Quantification of TREM1 PET tracer signal (saline ipsilateral, 2.1 6 0.45; saline contra- lateral, 2.1 6 0.33; isotype control ipsilateral, 1.9 6 0.29; isotype control contralateral, 1.8 6 0.35; TREM1 knockout ipsilateral, 3.1 6 0.57; TREM1 knockout contralateral, 2.8 6 0.97; day 7 6-hydrox- ydopamine ipsilateral, 2.7 6 0.45; day 7 6-hydroxydopamine contralateral, 2.4 6 0.48; day 14 6-hydroxydopamine ipsilateral, 2.7 6 0.23; day 14 6-hydroxydopamine contralateral, 2.2 6 0.43), ex vivo autoradiography (saline, 1.1 6 0.07; isotype control, 1.7 6 1.12; TREM1 knockout, 1.0 6 0.17; day 7 6-hydroxydopamine, 2.2 6 1.07; day 14 6-hydroxydopamine, 3.3 6 0.32), and g-counting quantification (brain: saline, 0.1 6 0.03; isotype control, 0.1 6 0.02; TREM1 knockout, 0.15 6 0.04; day 7 6-hydroxydopamine, 0.16 6 0.04; day 14 6-hydroxydopamine, 0.13 6 0.01; spleen: saline, 4.8 6 0.74; isotype control, 3.3 6 1.2; TREM1 knockout, 3.5 6 1.82; day 7 6-hydroxydopamine, 5.4 6 0.91; day 14 6-hydroxydopamine, 4.3 6 1.32) in saline, isotype control, and 6-hydroxydop- amine mice. All groups were compared with saline control (significance denoted by *); day 7 6-hydroxydopamine and isotype control were compared (significance denoted by #) as well as day 7 6-hydroxydopamine and TREM1 knockout (significance denoted by 1). Data are mean 6 SD per- centage injected dose per gram. */#P , 0.05. **/##/11P , 0.01. %ID 5 percentage injected dose; ARG 5 autoradiography; KO 5 knockout; OHDA 5 hydroxydopamine; ROI 5 region of interest.

Article Snippet: Mouse TREM1 mAb (R&D Systems) was conjugated with DOTAN-hydroxysuccinimide (Macrocyclics) using metal-free buffers and previously published procedures (25,32).

Techniques: Saline, Control, Knock-Out, Ex Vivo, Autoradiography, Injection

Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine

Article Title: Tracking Innate Immune Activation in a Mouse Model of Parkinson's Disease Using TREM1 and TSPO PET Tracers.

doi: 10.2967/jnumed.121.263039

Figure Lengend Snippet: FIGURE 7. Flow cytometry analysis of 6-hydroxydopamine and saline brains. (A) Flow cytometry analysis demonstrating frequency of peripheral myeloid (CD45hi [hi = high] CD11b-positive), lymphoid (CD45-positive CD11b-negative), and microglial (CD45int [int= intermediate] CD11b-positive) cells in brains of 6- hydroxydopamine and saline mice 7 d after stereotactic injection (myeloid: day 7 6-hydroxydopamine ipsilateral, 6.1 6 0.72; day 7 6-hydroxydopamine contra- lateral, 0.12 6 0.09; saline ipsilateral, 0.72 6 0.48; saline contralateral, 0.16 6 0.05; lymphoid: day 7 6-hydroxydopamine ipsilateral, 2.0 6 0.71; day 7 6- hydroxydopamine contralateral, 0.21 6 0.18; saline ipsilateral, 1.3 6 0.67; saline contralateral, 0.36 6 0.18; microglia: day 7 6-hydroxydopamine ipsilateral, 51.1 6 8.76; day 7 6-hydroxydopamine contralateral, 55.9 6 12.18; saline ipsilateral, 57.2 6 5.12; saline contralateral, 57.6 6 9.54). (B) Frequency of TREM1- positive myeloid, lymphoid, and microglial cells (TREM1-positive myeloid: day 7 6-hydroxydopamine ipsilateral, 1.6 6 0.73; day 7 6-hydroxydopamine contra- lateral, 0.03 6 0.025; saline ipsilateral, 0.42 6 0.36; saline contralateral, 0.026 6 0.023; TREM1-positive lymphoid: day 7 6-hydroxydopamine ipsilateral, 0.014 6 0.016; day 7 6-hydroxydopamine contralateral, 0.0068 6 0.01; saline ipsilateral, 0.016 6 0.014; saline contralateral, 0.011 6 0.0065; TREM1-positive micro- glia: day 7 6-hydroxydopamine ipsilateral, 0.39 6 0.14; day 7 6-hydroxydopamine contralateral, 0.23 6 0.18; saline ipsilateral, 0.42 6 0.061; saline contralat- eral, 0.45 6 0.22). Data are mean 6 SD percentage total live singlets. **P , 0.01. ***P , 0.001. ****P , 0.0001. OHDA 5 hydroxydopamine.

Article Snippet: Mouse TREM1 mAb (R&D Systems) was conjugated with DOTAN-hydroxysuccinimide (Macrocyclics) using metal-free buffers and previously published procedures (25,32).

Techniques: Flow Cytometry, Saline, Injection

Journal: bioRxiv

Article Title: Extracellular CIRP as a Novel Endogenous TREM-1 Ligand to Fuel Inflammation

doi: 10.1101/674218

Figure Lengend Snippet: (A) SPR between rmCIRP and rmTREM-1. Anti-his Ab was used to capture rmCIRP-his. rmTREM-1 was injected as an analyte in concentrations of 0 to 500 nM. (B) 1.5 × 10 4 RAW264.7 cells were treated with rmCIRP (5 μg/ml) at 4°C for 10 min, fixed in a nonpermeabilized fashion, and stained with rabbit anti-mouse CIRP Ab, goat anti-mouse TREM-1 Ab, goat anti-CD11b Ab, Cy5-conjugated AffiniPure donkey anti-goat IgG, and Cy3-conjugated AffiniPure F(ab’)2 fragment donkey anti-rabbit IgG. Confocal microscopy images were obtained at using a Zeiss LSM880 confocal microscope equipped with a 63× objective. Images were analyzed and quantified by using the ZenBlue software. ( C) After the staining protocol described in (B) , cell associated fluorescence was measured on Biotek Synergy Neo2 at 566 nm upon excitation at 488 nm ( E 1), at 681 nm after excitation at 630 nm ( E 2), and at 681 nm after excitation at 488 nm ( E 3). The transfer of fluorescence was calculated as FRET units. FRET unit = [ E 3 both − E 3 none ] − [( E 3 Cy5 − E 3 none ) × ( E 2 both / E 2 Cy5 )] − [( E 3 Cy3 − E 3 none ) × ( E 1 both / E 1 Cy3 )]. Data are expressed as means ± SE obtained from three independent experiments, n=9/group. Groups compared by unpaired t-test (*p<0.01 vs. CD11b). (D) A total of 1 × 10 6 /ml RAW264.7 cells were stimulated with rmCIRP (1 µg/ml) for various times. Extracted proteins were immunoprecipitated by using anti-DAP12 Ab, followed by Western blotting using pTyr (4G10) and DAP12 Ab. Extracted proteins obtained from rmCIRP (1 µg/ml for various times) stimulated RAW264.7 cells (1 × 10 6 /ml) were subjected to Western blotting using pSyk, Syk, and β–actin Abs. Representative western blots for phosphotyrosine (4G10), DAP12, pSyk, Syk, and β–actin are shown. (E, F) Each blot was quantified by densitometric analysis. Phosphotyrosine (pDAP12) and pSyk expression in each sample was normalized to DAP12 or Syk or β-actin expression and the mean values of 0 min of rmCIRP-treated groups were standardized as one for comparison. Data are expressed as means ± SE (n=6 samples/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. rmCIRP at 0 min). (G) RAW264.7 cells were transfected with TREM-1 siRNA, control siRNA, underwent mock transfection, or no transfection. Cells were then stimulated with PBS control or 1μg/ml rmCIRP. After 6 h, TNF-α in the supernatant was analyzed by ELISA. Data are expressed as means ± SE (n=3 samples/group). Multiple groups were compared by one-way ANOVA and Tukey method (*p<0.05 vs. respective PBS group; # p<0.01 vs. rmCIRP-treated non-transfected cells). (H) RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and stimulated with PBS or rmCIRP (1 µg/ml). Simultaneously cells were treated with various doses of LP-17 or LP-17-Sc1. After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE obtained from five independent experiments (n=3-10 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. PBS; #p<0.05 vs. rmCIRP+PBS). FRET, fluorescence resonance energy transfer; TNF, tumor necrosis factor; DAP12, DNAX activation protein of 12kDa; ELISA, enzyme-linked immunosorbent assay; PBS phosphate buffered saline.

Article Snippet: To detect TREM-1 expression on the surface of macrophages, a total of 1 × 10 6 RAW264.7 or primary peritoneal macrophages were washed with FACS buffer containing PBS with 2% FBS and stained with APC anti-mouse TREM-1 Ab (clone: 174021, R&D systems).

Techniques: Injection, Staining, Confocal Microscopy, Microscopy, Software, Fluorescence, Immunoprecipitation, Western Blot, Expressing, Comparison, Transfection, Enzyme-linked Immunosorbent Assay, Förster Resonance Energy Transfer, Activation Assay, Saline

Journal: bioRxiv

Article Title: Extracellular CIRP as a Novel Endogenous TREM-1 Ligand to Fuel Inflammation

doi: 10.1101/674218

Figure Lengend Snippet: (A) Partial amino acid sequence of murine CIRP highlighting an area of similarity between murine PGLYRP1. Three peptides (M1, M2, and M3) are highlighted from within the CIRP sequence. RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and treated with 10 µg/ml of peptides M1, M2, or M3 for 30 min. Cells were then stimulated with rmCIRP (1 µg/ml). After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE obtained from two independent experiments (n=6 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. unstimulated cells and #p<0.05 vs. rmCIRP-treated cells). (B) SPR between rmTREM-1 and M3. M3 was injected as an analyte in concentrations of 0 to 20 μM. (C) RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and treated with M3 or M3-Sc1 at a dose of 10 µg/ml for 30 min. Cells were then stimulated with PBS or rmCIRP (5 µg/ml) at 4°C for 10 min, fixed in a nonpermeabilized fashion, and stained as described in 1B. FRET analysis was performed as described in 1B. Data are expressed as means ± SE obtained from three independent experiments, n=9/group. Multiple groups were compared by one-way ANOVA and Tukey method (*p<0.05 vs CD11b + rmCIRP, #p<0.05 vs TREM-1 + rmCIRP). (D) To activate RAW264.7 cells through TREM-1, 96-well flat bottom plates were pre-coated with 20 μg/ml of an agonist anti-TREM-1 mAb overnight at 37°C. The wells were washed with sterile PBS and 5 × 10 4 cells/well were plated. Prior to plating, cells were premixed with either PBS control, M3 (10 μg/ml) or scramble M3-Sc1 (10 μg/ml) for 30 min. After plating, TNF-α production was measured in the culture supernatants after an additional 24 h of incubation. Data are expressed as means ± SE. The experiment was performed two independent times with n=5 wells per group. Multiple groups were compared by one-way ANOVA and Tukey method (*p<0.05 vs. uncoated; #p<0.05 vs. TREM-1 Ab + PBS). (E) RAW264.7 cells (1×10 4 cells/ml) were plated in 96-well culture plate and treated with various doses of M3, M3-Sc1, or M3-Sc1 for 30 min. Cells were then stimulated with PBS or rmCIRP (1 µg/ml). After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE obtained from three independent experiments (n=4 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. PBS-treated cells; #p<0.05 vs. rmCIRP + PBS). (F) Macrophages from healthy human donors (1×10 4 cells/ml) were plated in 96-well culture plate and treated with various doses of M3 for 30 minutes. Cells were then stimulated with PBS or rmCIRP (1 µg/ml). After 24 h, TNF-α in culture supernatants at protein level were measured by ELISA. Data are expressed as means ± SE (n=5 wells/group). The groups were compared by one-way ANOVA and SNK method (*p<0.05 vs. PBS-treated cells; #p<0.05 vs. rmCIRP + PBS). FRET, fluorescence resonance energy transfer; TNF, tumor necrosis factor; ELISA, enzyme-linked immunosorbent assay; PBS, phosphate buffered saline; PGLYRP1, peptidoglycan recognition protein 1.

Article Snippet: To detect TREM-1 expression on the surface of macrophages, a total of 1 × 10 6 RAW264.7 or primary peritoneal macrophages were washed with FACS buffer containing PBS with 2% FBS and stained with APC anti-mouse TREM-1 Ab (clone: 174021, R&D systems).

Techniques: Sequencing, Enzyme-linked Immunosorbent Assay, Injection, Staining, Sterility, Incubation, Fluorescence, Förster Resonance Energy Transfer, Saline

Journal: bioRxiv

Article Title: Extracellular CIRP as a Novel Endogenous TREM-1 Ligand to Fuel Inflammation

doi: 10.1101/674218

Figure Lengend Snippet: Sepsis and I/R causes an increased release of eCIRP. As the endogenous ligand eCIRP recognizes TREM-1 and activates intracellular signaling molecules DAP12 and Syk, leading to increased expression of pro-inflammatory mediators that cause excessive inflammation and remote tissue injury. eCIRP increases TREM-1 expression, possibly via positive feedback induction. A small peptide M3 derived from human eCIRP abrogates eCIRP-TREM-1 interaction, thereby leading to decreased inflammation and attenuated ALI. I/R, ischemia and reperfusion; DAP12, DNAX activation protein of 12kDa; ALI, acute lung injury.

Article Snippet: To detect TREM-1 expression on the surface of macrophages, a total of 1 × 10 6 RAW264.7 or primary peritoneal macrophages were washed with FACS buffer containing PBS with 2% FBS and stained with APC anti-mouse TREM-1 Ab (clone: 174021, R&D systems).

Techniques: Expressing, Derivative Assay, Activation Assay

Journal: Frontiers in Immunology

Article Title: Identification of Extracellular Actin As a Ligand for Triggering Receptor Expressed on Myeloid Cells-1 Signaling

doi: 10.3389/fimmu.2017.00917

Figure Lengend Snippet: FACS analysis of surface triggering receptor expressed on myeloid cells-1 (TREM-1) and its ligand on cells. Mice ( n = 5) were inoculated with LPS for 6 h or mock treated with PBS as a control. The blood cells were collected, and red blood cells were removed for analysis of TREM-1 expression or analysis of the distribution of TREM-1-interacting proteins. All experiments were done in triplicate. (A) FACS analysis of TREM-1 expression on the cell surface with phycoerythrin (PE)-conjugated rat anti-mouse TREM-1 or PE Rat IgG2a, κ Isotype ctrl Antibody, allophycocyanin-conjugated anti-mouse F4/80, and Percp/cy5.5-conjugated anti-mouse Ly-6G. The signal for TREM-1 was specific (Figure in Supplementary Material), and the cells expressing TREM-1 was further analyzed (Figure in Supplementary Material). (B) FACS analysis of the distribution of TREM-1-interacting proteins on cells with Cy5.5-NHS-Ester-labeled recombinant extracellular domain of mouse TREM-1 (rTREM-1), PE/Cy7-conjugated anti-mouse CD41, and PE-conjugated anti-mouse Ly-6G. The cells expressing the ligand for TREM-1 were shown in details (Figure in Supplementary Material).

Article Snippet: The cells were then stained with allophycocyanin-conjugated anti-mouse F4/80 (BioLegend), Percp/cy5.5-conjugated anti-mouse Ly-6G (BioLegend), and phycoerythrin (PE)-conjugated rat IgG2A anti-mouse TREM-1 (R&D systems) or PE-conjugated Rat IgG2a, κIsotype Ctrl Antibody (BioLegend) to analyze which cells expressed surface TREM-1.

Techniques: Control, Expressing, Labeling, Recombinant

Journal: Frontiers in Immunology

Article Title: Identification of Extracellular Actin As a Ligand for Triggering Receptor Expressed on Myeloid Cells-1 Signaling

doi: 10.3389/fimmu.2017.00917

Figure Lengend Snippet: Analysis of the co-localization of triggering receptor expressed on myeloid cells-1 (TREM-1) and actin by laser scanning confocal microscopy. RAW264.7 cells were mock treated with PBS or treated with LPS, platelets, or rACTIN. All cells were fixed and then incubated with mouse TREM-1 antibody antigen affinity-purified polyclonal goat IgG and rabbit anti-beta actin polyclonal antibody, followed by FITC-conjugated affinipure donkey anti-rabbit IgG (H + L) and CY3-conjugated affinipure donkey anti-goat IgG (H + L). After staining the nuclei with Hoechest 33258, the slides were analyzed with a LSM880 with Airyscan laser scanning confocal microscope and ZEN2.3 LITE software. The scale bars in the figure represent 10 µm.

Article Snippet: The cells were then stained with allophycocyanin-conjugated anti-mouse F4/80 (BioLegend), Percp/cy5.5-conjugated anti-mouse Ly-6G (BioLegend), and phycoerythrin (PE)-conjugated rat IgG2A anti-mouse TREM-1 (R&D systems) or PE-conjugated Rat IgG2a, κIsotype Ctrl Antibody (BioLegend) to analyze which cells expressed surface TREM-1.

Techniques: Confocal Microscopy, Incubation, Affinity Purification, Staining, Microscopy, Software

Journal: Frontiers in Immunology

Article Title: Identification of Extracellular Actin As a Ligand for Triggering Receptor Expressed on Myeloid Cells-1 Signaling

doi: 10.3389/fimmu.2017.00917

Figure Lengend Snippet: Analysis of the co-localization of triggering receptor expressed on myeloid cells-1 (TREM-1) and actin in lung sections of cecal ligation and puncture (CLP) mice or healthy control mice. The lung sections from CLP mice ( n = 3) or mock-treated mice ( n = 3) were stained with mouse TREM-1 antibody antigen affinity-purified polyclonal goat IgG and rabbit anti-beta actin polyclonal antibody, followed by FITC-conjugated affinipure donkey anti-rabbit IgG (H + L) and CY3-conjugated affinipure donkey anti-goat IgG (H + L). The cells were analyzed with Fluoview™ Fv1000 laser scanning confocal microscope and FV10-ASW3.1 viewer software. The scale bars in the figure represent 20 µm.

Article Snippet: The cells were then stained with allophycocyanin-conjugated anti-mouse F4/80 (BioLegend), Percp/cy5.5-conjugated anti-mouse Ly-6G (BioLegend), and phycoerythrin (PE)-conjugated rat IgG2A anti-mouse TREM-1 (R&D systems) or PE-conjugated Rat IgG2a, κIsotype Ctrl Antibody (BioLegend) to analyze which cells expressed surface TREM-1.

Techniques: Ligation, Control, Staining, Affinity Purification, Microscopy, Software