complement c3/c3a, mouse  (MedChemExpress)

Journal: bioRxiv

Article Title: Complement Dysregulation During the Early Phases of Synucleinopathy

doi: 10.64898/2026.04.27.720696

Figure Lengend Snippet: The complement system is an arm of innate immunity, comprising ∼50 proteins present throughout 8ssues and ac8vated by proteoly8c cleavage. a) Complement ac8va8on occurs via one of three pathways: classical, lec8n, and alterna8ve. The classical pathway is ini8ated when C1q binds targets, ac8va8ng C1r and C1s, which cleave C4 and C2 to form the C3 convertase, C4b2a. The lec8n pathway is triggered by mannose-binding lec8n (MBL), collec8ns, or ficolins recognizing microbial- or altered self-carbohydrates, ac8va8ng MASP-1 and MASP-2 to generate the C3 convertase, C4b2a. The alterna8ve pathway is cons8tu8vely ac8ve through spontaneous C3 hydrolysis, forming the free C3 convertase C3(H2O)Bb, and is amplified on surfaces to form the alterna8ve pathways C3 convertase, C3bBb, enhancing complement ac8va8on. b) The central event in the cascade is cleavage of C3 by the C3 convertases to form C3a and C3b, which ini8ate the major effector responses of the system. c) Opsoniza9on/Phagocytosis : C3b and iC3b deposited on target surfaces promote phagocytosis via CR1, CR3, and CR4. Inflammatory Signaling : The anaphylatoxin pep8des, C3a and C5a, mediate inflammatory signaling through C3aR and C5aR, driving chemotaxis, cytokine produc8on, and ac8va8on of immune cells. Membrane ACack Complex (MAC) : C5b ini8ates the terminal pathway by recrui8ng C6–C9 to form the MAC, lysing target cells. Complement ac8vity is 8ghtly regulated at mul8ple levels (shown in pink boxes): C1 inhibitor (C1-INH) and neuronal pentraxins (NPTXs) restrain classical ini8a8on, C4 binding protein (C4BP), Factor H (FH), and FI regulate C3 convertases and alterna8ve pathway amplifica8on; carboxypep8dase-N (CPN) inac8vates anaphylatoxins; the membrane bound regulators CR1, CD46, CD55, and CD59 prevent deposi8on of ac8vated complement on self-cells; clusterin (CLU) and vitronec8n (VTN) prevent MAC assembly and inser8on. Representa8ve complement components (shown in red text) were quan8fied in α-synuclein pre-formed fibril–injected rats and postmortem PD brains.

Article Snippet: Wells were then washed four times with 200μL of PBS-T and incubated in 50μL of a primary antibody specific to a neo-epitope in cleaved (activated) complement C3 (1:500; Hycult HM2257; RRID:AB_1953566) diluted in 2% BSA for 1 hour at RT with gentle shaking.

Techniques: Binding Assay, Amplification, Chemotaxis Assay, Membrane, Injection

Journal: bioRxiv

Article Title: Complement Dysregulation During the Early Phases of Synucleinopathy

doi: 10.64898/2026.04.27.720696

Figure Lengend Snippet: Rats (n=6-8/sex/group) received intra-striatal injec8ons of α-synuclein (α-syn) preformed fibrils (PFFs) or phosphate buffer saline (PBS) and were sacrificed 2-months post-injec8on. A-b) Representa8ve images of Serine 129 phosphorylated α-syn (pSyn) immunostaining in the substan8a nigra (SN) of PBS ( a ) and α-syn PFF ( b ) injected rats. C-d ) Representa8ve images of MHC-II immunostaining in the SN of PBS ( c ) and α-syn PFF ( d ) injected rats. High magnifica8on images to the right of each panel correspond to the area in the box of respec8ve low magnifica8on images. E-F ) Droplet digital PCR (ddPCR) quan8fica8on of complement component 3 ( C3) expression in the striatum (ST; panel e ) and SN ( f ). Data are C3 normalized to ribosomal potein L13 ( Rpl13 ), analyzed with t-test with Welch’s correc8on. g ) Representa8ve immunoblot of pSyn, α-syn and β-ac8n from the ST. h ) Quan8fica8on of pSyn monomers (∼14-17 kDa), i ) pSyn mul8mers (∼20-50 kDa), j ) total pSyn signal (∼14-50 kDa), and k ) α-syn monomer (∼14-17 kDa) normalized to β-ac8n in the ST. l) Representa8ve immunoblot of pSyn, α-syn and β-ac8n from the SN. m ) Quan8fica8on of pSyn monomers (∼14-17 kDa), n ) pSyn mul8mers (∼20-50 kDa), o ) total pSyn signal (∼14-50 kDa), and p ) α-syn monomer (∼14-17 kDa) normalized to β-ac8n in the SN. q) Representa8ve immunoblot of C3 and β-ac8n from the ipsilateral ST. s ) Representa8ve immunoblot of C3 and β-ac8n from the ipsilateral SN Quan8fica8on of C3 whole molecule (∼190 kDa), C3 α-chain (∼115 kDa), iC3b α-chain (∼75 kDa), and C3c α-chain (∼34kDa) normalized to β-ac8n from the ST ( r ) and SN ( t ), analyzed with t-test with Welch’s correc8on). Scale bars in large images of ( b, d) are 250μm and apply to large images of ( a-d) , while scale bar in the small images of ( b, d) are 50μm and apply to small images of ( a-d) . All data are group means ± standard devia8on expressed a fold change from PBS group.

Article Snippet: Wells were then washed four times with 200μL of PBS-T and incubated in 50μL of a primary antibody specific to a neo-epitope in cleaved (activated) complement C3 (1:500; Hycult HM2257; RRID:AB_1953566) diluted in 2% BSA for 1 hour at RT with gentle shaking.

Techniques: Saline, Immunostaining, Injection, Digital PCR, Expressing, Western Blot

Journal: bioRxiv

Article Title: Complement Dysregulation During the Early Phases of Synucleinopathy

doi: 10.64898/2026.04.27.720696

Figure Lengend Snippet: Male and female rats (n=5-6/group) received intra-striatal injec8ons of α-synuclein (α-syn) preformed fibrils (PFFs) or phosphate buffer saline (PBS) and were sacrificed 2 months post injec8on. a-h ) Representative low magnification immunofluorescent (IF) images of Huc/d (cyan, neuronal marker), serine 129 phosphorylated α-syn (pSyn; green) and complement component 3 (C3; red) and the overlay image in the SNc of PBS ( a-d ) and PFF ( e-h ) injected rats. i-p ) High magnification images corresponding to box in ( d ) and ( h ), for PBS ( i-l ) and PFF injected ( m-p ) rats, respectively. q-r ) Quantification of C3 ( q ) and pSyn ( r ) fluorescence intensity. s ) Regression analysis between pSyn and C3 fluorescence intensity in the SNc of PFF injected rats. t-u ) Quantification of percent area of SNc occupied by C3+ ( t ) and pSyn+ ( u ) staining. v ) Regression analysis between pSyn and C3 percent area staining in the SNc of PFF injected rats. Data expressed as mean fold change (± standard deviation) from PBS controls, analyzed by t-test with Welch’s correction or simple linear regression analyses. w-z ) Representative IF images of pSyn (green; panel w ), the microglial marker, ionized calcium binding adapter molecule 1 (IBA1; cyan; panel x ), C3 (red; panel; y ) and the overlay image ( z ) in the SNc of PFF injected rats. Arrows in ( m-p ) and ( w-z ) indicate areas where C3+ microglia are in direct apposition of neurons containing pSyn+ aggregates. Scale bars in ( h ) is 250μm and applies to ( a-h ), scale bar in ( p ) is 50μm and applies to ( i-p ), scale bar in ( z ) is 50μm and applies to ( w-z )

Article Snippet: Wells were then washed four times with 200μL of PBS-T and incubated in 50μL of a primary antibody specific to a neo-epitope in cleaved (activated) complement C3 (1:500; Hycult HM2257; RRID:AB_1953566) diluted in 2% BSA for 1 hour at RT with gentle shaking.

Techniques: Saline, Marker, Injection, Fluorescence, Staining, Standard Deviation, Binding Assay

Journal: bioRxiv

Article Title: Complement Dysregulation During the Early Phases of Synucleinopathy

doi: 10.64898/2026.04.27.720696

Figure Lengend Snippet: Male and female rats (n=5-6/group) received intra-striatal injec8ons of α-synuclein (α-syn) preformed fibrils (PFFs) or phosphate buffer saline (PBS) and sacrificed 2-months post-injec8on. a-h ) Representative low magnification images of DAPI (blue, nuclear marker), pSyn (green, phospho-Ser129 α-syn) and C3 (red, complement 3) and the overlay in the ipsilateral cortex (Cx) of PBS ( a-d ) and α-syn PFF ( e-h ) injected rats. i-p) High magnification images corresponding to box in ( d ) and ( h ), for PBS ( i-l ) and PFF ( m-p ) injected rats, respectively. q-r ) Quantification of C3 ( q ) and pSyn ( r ) fluorescence intensity in the Cx. s ) Linear regression between pSyn and C3 fluorescence intensity in the Cx of PFF injected rats. t-u) Quantification of percent area of Cx occupied by C3+ ( t ) and pSyn+ ( u ) staining. v ) Linear regression between pSyn and C3 percent area staining in the Cx of PFF injected rats. w-dd ) Representative low magnification images of DAPI (blue), pSyn (green) and C3 (red) and overlay image in the ipsilateral striatum (ST) of PBS ( w-z ) and PFF ( aa-dd ) injected rats. ee-ll) High magnification images corresponding to box in ( z ) and ( dd ), for PBS ( ee-hh ) and PFF ( ii-ll ) injected rats, respectively. mm-nn ) Quantification of C3 ( mm ) and pSyn ( nn ) fluorescence intensity in the ST. oo ) Linear regression between pSyn and C3 fluorescence intensity in the ST of PFF injected rats. pp-qq) Quantification of percent area of ST occupied by C3+ ( pp ) and pSyn+ ( qq ) staining. rr ) Linear regression between pSyn and C3 percent area staining in the ST of PFF injected rats. Data expressed as mean fold change (± standard deviation) from PBS controls (analyzed with unpaired t-test with Welch’s correction or simple linear regression analyses). Scale bars in ( h; dd) are 250μm and apply to ( a-h; w-dd) , respectively. Scale bars in ( p; ll) are 50μm and apply to ( i-p; ee-ll) , respectively.

Article Snippet: Wells were then washed four times with 200μL of PBS-T and incubated in 50μL of a primary antibody specific to a neo-epitope in cleaved (activated) complement C3 (1:500; Hycult HM2257; RRID:AB_1953566) diluted in 2% BSA for 1 hour at RT with gentle shaking.

Techniques: Saline, Marker, Injection, Fluorescence, Staining, Standard Deviation

Journal: Bioactive Materials

Article Title: Splenic dendritic cell-targeting mRNA transfection of H-type ionizable lipid-based LNPs for enhancing tumor immunotherapy

doi: 10.1016/j.bioactmat.2026.02.018

Figure Lengend Snippet: Schematic illustration of in vivo tumor immunotherapy enhanced by mRNA/HNPs through intravenous injection. H18 lipid, DOPE, cholesterol, DMG-PEG 2000 and mRNA were mixed to form mRNA/H 18 NPs with the special multilamellar concentric nanostructures. Following intravenous administration, mRNA/H 18 NPs demonstrated preferential adsorption of complement C3 proteins to form a characteristic protein corona, resulting in specific mRNA transfection in the spleen, especially in splenic dendritic cells. When encapsulating tumor antigen-encoding mRNA, the mRNA/H 18 NPs achieved precise transfection of the antigen mRNA in splenic dendritic cells. This targeted delivery stimulated dendritic cell maturation and subsequent antigen presentation, initiating robust T cell priming. The activated antigen-specific cytotoxic T lymphocytes then infiltrated into tumor tissues, ultimately inducing tumor cell elimination.

Article Snippet: Mouse Complement C3 was purchased from MedChemExpress.

Techniques: In Vivo, Injection, Adsorption, Transfection, Immunopeptidomics

Journal: Bioactive Materials

Article Title: Splenic dendritic cell-targeting mRNA transfection of H-type ionizable lipid-based LNPs for enhancing tumor immunotherapy

doi: 10.1016/j.bioactmat.2026.02.018

Figure Lengend Snippet: In vivo splenic DC-specific transfection of mRNA/H 18 NPs and in vitro protein corona analysis of mRNA/H 18 NPs. (A) EGFP protein expression in splenic cell subsets of C57BL/6J mice 24 h post intravenous injection of different formulations. (B) The top 5 most abundant plasma proteins adsorbed on mRNA/H 18 NPs (C3: Complement C3; Ighm: Immunoglobulin heavy constant mu; Hbat1: Alpha-globin; Itih4: Inter alpha-trypsin inhibitor, heavy chain 4; Cnn2: Calponin). (C) Heatmap plot of major proteins in the protein corona adsorbed on mRNA/MC3-LNPs and mRNA/H 18 NPs. PBS group was used as a negative control. (D) Quantification of major adsorbed protein categories of different formulations. (E) Complement C3 abundance in protein corona adsorbed on mRNA/MC3-LNPs and mRNA/H 18 NPs. (F) Bioluminescence images of major organs and (G) Quantification of total bioluminescence flux in the spleen from C57BL/6J mice 6 h after intravenous injection of mLuc/H 18 NPs (mLuc dose of 0.25 mg kg −1 ). Mice were pre-treated with cobra venom factor (CVF) or PBS. (H) Fluorescence quantification of Cy5 mRNA delivered by uncoated or complement C3-coated Cy5-mRNA/H 18 NPs in BMDCs. BMDCs were pre-incubated with anti-CD11b (CR3) or anti-IgG blocking antibody. (I) Bioluminescence intensity of luciferase protein translated from mRNA delivered by uncoated or complement C3-coated mLuc/H 18 NPs in BMDCs. BMDCs were pre-incubated with anti-CD11b (CR3) or anti-IgG blocking antibody. Data were shown as mean ± SD (n = 3).

Article Snippet: Mouse Complement C3 was purchased from MedChemExpress.

Techniques: In Vivo, Transfection, In Vitro, Expressing, Injection, Clinical Proteomics, Negative Control, Combined Bisulfite Restriction Analysis Assay, Fluorescence, Incubation, Blocking Assay, Luciferase

Journal: Blood Vessels, Thrombosis & Hemostasis

Article Title: A second generation of C3 humanized rats for preclinical evaluation of human C3 inhibitors

doi: 10.1016/j.bvth.2026.100138

Figure Lengend Snippet: C3 inhibitor AMY-101 inhibits the alternative but not classical pathway complement-mediated hemolysis in the second-generation hC3 rats in vitro. (A) The C3 inhibitor AMY-101 (0.3-20μM) was incubated with rabbit RBCs in the presence of 80% WT rat serum, or second-generation hC3 rat serum in Mg 2+ -EGTA buffer at 37°C for 30 minutes, then hemolysis was quantitated, showing that AMY-101 almost completely inhibited the second-generation hC3 rat alternative pathway-mediated hemolysis at a concentration as low as 2.5μM while did not affect the WT rat alternative pathway-mediated hemolysis at a concentration as high as 20μM. (B) The C3 inhibitor AMY-101 (0.3-10μM) were incubated with antibody-sensitized sheep RBCs in the presence of 10% second-generation hC3 rat serum in GVB ++ buffer at 37°C for 30 minutes, then hemolysis was quantitated, showing that AMY-101 did not have any effect on the second-generation hC3 rat classical pathway-mediated hemolysis at a concentration as high as 10μM. 2nd gen, second generation.

Article Snippet: In these assays, human and rat C3 proteins were detected using a complement C3 polyclonal antibody (MP Biomedicals, catalog no. 0855117) and a secondary anti-goat immunoglobulin G (IgG) (heavy chain+light chain [H+L]) polyclonal antibody (SouthernBiotech, catalog no. 6160-05).

Techniques: In Vitro, Incubation, Concentration Assay