Linkage Specificity and Role of Properdin in Activation of the Alternative Complement Pathway by Fungal Glycans

Agarwal, Sakshi; Specht, Charles A.; Huang, Haibin; Ostroff, Gary R.; Ram, Sanjay; Rice, Peter A.; Levitz, Stuart M.

doi:10.1128/mbio.00178-11

Cited by 36 publications

(45 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…6 and 7). When properdin, which is a positive regulator of the alternative pathway, is blocked, the alternative complement pathway is decreased but not totally eliminated (2). In contrast, when factor B is blocked, we would expect more complete inhibition of the alternative pathway.…”

Section: Discussionmentioning

confidence: 89%

Combined Roles of Human IgG Subclass, Alternative Complement Pathway Activation, and Epitope Density in the Bactericidal Activity of Antibodies to Meningococcal Factor H Binding Protein

Giuntini¹,

Reason²,

Granoff³

2012

Infect Immun

View full text Add to dashboard Cite

Meningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding. Since IgG subclasses differ in their ability to activate complement, we investigated the role of human IgG subclasses on antibody functional activity. We constructed chimeric MAbs in which three different murine fHbp-specific binding domains were each paired with human IgG1, IgG2, or IgG3. Against a wild-type group B isolate, all three IgG3 MAbs, irrespective of their ability to inhibit fH binding, had bactericidal activity that was >5-fold higher than the respective IgG1 MAbs, while the IgG2 MAbs had the least activity. Against a mutant with increased fHbp expression, the anti-fHbp MAbs elicited greater C4b deposition (classical pathway) and greater bactericidal activity than against the wild-type strain, and the IgG1 MAbs had similar or greater activity than the respective IgG3 MAbs. The bactericidal activity against both wild-type and mutant strains also was dependent, in part, on activation of the alternative complement pathway. Thus, at lower epitope density in the wild-type strain, the IgG3 anti-fHbp MAbs had the greatest bactericidal activity. At a higher epitope density in the mutant, the IgG1 MAbs had similar or greater bactericidal activity than the IgG3 MAbs, and the activity was less dependent on the inhibition of fH binding than at a lower epitope density.

show abstract

Section: Discussionmentioning

confidence: 89%

Combined Roles of Human IgG Subclass, Alternative Complement Pathway Activation, and Epitope Density in the Bactericidal Activity of Antibodies to Meningococcal Factor H Binding Protein

Giuntini¹,

Reason²,

Granoff³

2012

Infect Immun

View full text Add to dashboard Cite

show abstract

“…Previously, properdin has been shown to bind AP activator surfaces strictly in a C3-dependent manner (33,35). However, several lines of recent evidence suggest that properdin by itself may provide a platform for the in situ assembly of C3bBb complex on target surfaces, therefore providing new insights into properdin function (31,36).…”

Section: Discussionmentioning

confidence: 99%

Soluble Collectin-12 (CL-12) Is a Pattern Recognition Molecule Initiating Complement Activation via the Alternative Pathway

Jie

Hein

Munthe-Fog

et al. 2015

The Journal of Immunology

View full text Add to dashboard Cite

Soluble defense collagens including the collectins play important roles in innate immunity. Recently, a new member of the collectin family named collectin-12 (CL-12 or CL-P1) has been identified. CL-12 is highly expressed in umbilical cord vascular endothelial cells as a transmembrane receptor and may recognize certain bacteria and fungi, leading to opsonophagocytosis. However, based on its structural and functional similarities with soluble collectins, we hypothesized the existence of a fluid-phase analog of CL-12 released from cells, which may function as a soluble pattern-recognition molecule. Using recombinant CL-12 full length or CL-12 extracellular domain, we determined the occurrence of soluble CL-12 shed from in vitro cultured cells. Western blot showed that soluble recombinant CL-12 migrated with a band corresponding to ∼120 kDa under reducing conditions, whereas under nonreducing conditions it presented multimeric assembly forms. Immunoprecipitation and Western blot analysis of human umbilical cord plasma enabled identification of a natural soluble form of CL-12 having an electrophoretic mobility pattern close to that of shed soluble recombinant CL-12. Soluble CL-12 could recognize Aspergillus fumigatus partially through the carbohydrate-recognition domain in a Ca2+-independent manner. This led to activation of the alternative pathway of complement exclusively via association with properdin on A. fumigatus as validated by detection of C3b deposition and formation of the terminal complement complex. These results demonstrate the existence of CL-12 in a soluble form and indicate a novel mechanism by which the alternative pathway of complement may be triggered directly by a soluble pattern-recognition molecule.

show abstract

“…As a control, we used yeast glucan particles, a potent activator of the alternative pathway (29) to verify that the anti-Bb could block C3 deposition (see Fig. S4 in the supplemental material).…”

Section: Resultsmentioning

confidence: 99%

Fusion Protein Comprising Factor H Domains 6 and 7 and Human IgG1 Fc as an Antibacterial Immunotherapeutic

Shaughnessy

Vu²,

Punjabi

et al. 2014

Clin Vaccine Immunol

Self Cite

View full text Add to dashboard Cite

bThe emergence of antimicrobial resistance among several medically important pathogens represents a serious threat to human health globally and necessitates the development of novel therapeutics. Complement forms a key arm of innate immune defenses against invading pathogens. A mechanism of complement evasion employed by many pathogens is binding of complement inhibitors, including factor H (FH), a key downregulator of the alternative pathway. Most FH-binding bacteria engage FH through regions in FH spanned by domains 6 and 7 and/or 18 through 20. We created a chimeric protein that comprised human FH domains 6 and 7 fused to human IgG1 Fc (FH6,7/HuFc) and tested its activity as an immunotherapeutic against Neisseria meningitidis, which binds FH through domains 6 and 7. FH6,7/HuFc bound to meningococci and effectively blocked FH binding to bacteria. FH6,7/HuFc enhanced human C3 and C4 deposition and facilitated complement-mediated killing in a dose-responsive manner; complement activation and killing were classical pathway dependent. To investigate in vivo efficacy, infant Wistar rats were treated intraperitoneally (IP) with different doses of FH6,7/HuFc and challenged 2 h later with serogroup C strain 4243 given IP. At 8 to 9 h after the challenge, the FH6,7/HuFc-treated rats had >100-fold fewer CFU per ml of blood than control animals pretreated with phosphate-buffered saline (PBS) or FH18 -20/HuFc, which does not bind to meningococci (P < 0.0001). These data provide proof of concept of the utility of FH/Fc fusion proteins as anti-infective immunotherapeutics. Because many microbes share a common binding region(s) in FH, FH/Fc chimeric proteins may be a promising candidate for adjunctive therapy against drug-resistant pathogens.

show abstract

Linkage Specificity and Role of Properdin in Activation of the Alternative Complement Pathway by Fungal Glycans

Cited by 36 publications

References 54 publications

Combined Roles of Human IgG Subclass, Alternative Complement Pathway Activation, and Epitope Density in the Bactericidal Activity of Antibodies to Meningococcal Factor H Binding Protein

Combined Roles of Human IgG Subclass, Alternative Complement Pathway Activation, and Epitope Density in the Bactericidal Activity of Antibodies to Meningococcal Factor H Binding Protein

Soluble Collectin-12 (CL-12) Is a Pattern Recognition Molecule Initiating Complement Activation via the Alternative Pathway

Fusion Protein Comprising Factor H Domains 6 and 7 and Human IgG1 Fc as an Antibacterial Immunotherapeutic

Contact Info

Product

Resources

About