A Factor H-Fc fusion protein increases complement-mediated opsonophagocytosis and killing of community associated methicillin-resistant Staphylococcus aureus

• Published in: PloS one 2022-03, Vol.17 (3), p.e0265774-e0265774
• Main Authors: Sage, Megan A G, Cranmer, Katelyn D, Semeraro, Michele L, Ma, Shelby, Galkina, Elena V, Tran, Y, Wycoff, Keith L, Sharp, Julia A
• Format: Article
• Language: English
• Subjects: Anaphylatoxins; Antibiotic resistance; Antibiotics; Bacterial diseases; Biology; Biology and Life Sciences; Care and treatment; Clinical isolates; Complement; Complement C3b - metabolism; Complement component C3; Complement component C3b; Complement component C5a; Complement Factor H; Complement system; Complement System Proteins - metabolism; Drug resistance; Drug resistance in microorganisms; Evaluation; Fc receptors; Fusion protein; Immune system; Immunoglobulin G; Infection control; Innate immunity; Leukocytes (polymorphonuclear); Medical schools; Medicine and Health Sciences; Methicillin; Methicillin-Resistant Staphylococcus aureus - metabolism; Mutation; Opsonization; Opsonophagocytosis; Protein Binding; Proteins; Staphylococcus aureus; Staphylococcus aureus - metabolism; Staphylococcus aureus infections; Staphylococcus infections; Tactics; Virulence; Virulence factors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0265774

Staphylococcus aureus employs a multitude of immune-evasive tactics to circumvent host defenses including the complement system, a component of innate immunity central to controlling bacterial infections. With antibiotic resistance becoming increasingly common, there is a dire need for novel therapies. Previously, we have shown that S. aureus binds the complement regulator factor H (FH) via surface protein SdrE to inhibit complement. To address the need for novel therapeutics and take advantage of the FH:SdrE interaction, we examined the effect of a fusion protein comprised of the SdrE-interacting domain of FH coupled with IgG Fc on complement-mediated opsonophagocytosis and bacterial killing of community associated methicillin-resistant S. aureus. S. aureus bound significantly more FH-Fc compared to Fc-control proteins and FH-Fc competed with serum FH for S. aureus binding. FH-Fc treatment increased C3-fragment opsonization of S. aureus for both C3b and iC3b, and boosted generation of the anaphylatoxin C5a. In 5 and 10% serum, FH-Fc treatment significantly increased S. aureus killing by polymorphonuclear cells. This anti-staphylococcal effect was evident in 75% (3/4) of clinical isolates tested. This study demonstrates that FH-Fc fusion proteins have the potential to mitigate the protective effects of bound serum FH rendering S. aureus more vulnerable to the host immune system. Thus, we report the promise of virulence-factor-targeted fusion-proteins as an avenue for prospective anti-staphylococcal therapeutic development.