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Orthopaedic Proceedings

Vol. 106-B, Issue SUPP_19 | Pages 66 - 66

22 Nov 2024

RADIOIMMUNOTHERAPY COMBATING METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS AND ITS BIOFILM IN VITRO

Ye Z van der Wildt B Vogely C Weinans H Poot A van der Wal B

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Aim

Prosthetic joint infections (PJI) remain a great challenge in orthopedic surgery with a high mortality rate. It is particularly complicated by biofilms and infections caused by Methicillin-resistant Staphylococcus aureus (MRSA). It concurrently shields bacteria from host immune responses and confers resistance to antibiotics. This study aims to investigate the efficacy of radioimmunotherapy as an innovative therapeutic modality to address the challenges posed by MRSA and its biofilm.

Method

We induced specific monoclonal antibodies 4497-IgG1 as carriers, which target wall teichoic acids (WTA) existing on MRSA and its biofilm. Radionuclides actiniumr-225 (²²⁵Ac, α-emitter) and lutetium-177 (¹⁷⁷Lu, β-emitter) were conjugated with mAbs using DOTA as chelator. Quality control was assessed using thin layer chromatography and immunoreactivity assays. ²²⁵Ac- and ¹⁷⁷Lu-labelled 4497-IgG1 were employed to evaluate the susceptibility of MRSA and its biofilm to the radioimmunotherapy in vitro. Planktonic MRSA and biofilms, at concentrations of 10⁸ and 10⁷ CFU/mL, were incubated at 37°C for 60 minutes in PBS containing either ²²⁵Ac-mAb (0 - 14.8 kBq) or ¹⁷⁷Lu-mAb (0 - 14.8 MBq). Radiolabelled dunituximab and free radionuclides serve as isotype-matched negative control. The bacterial viability and metabolic activity were subsequently quantified using CFU and XTT assays.

Orthopaedic Proceedings

Vol. 101-B, Issue SUPP_14 | Pages 25 - 25

1 Dec 2019

DEVELOPMENT OF ANTIBODIES THAT ENHANCE IMMUNE CLEARANCE OF STAPHYLOCOCCAL BIOFILMS

de Vor L Van Kessel K De Haas C Aerts P Viveen M Boel E Fluit A van Dijk B Vogely C van der Wal B van Strijp J Weinans H Rooijakkers S

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Aim

“Implant associated Staphylococcus aureus or S. epidermidis infections are often difficult to treat due to the formation of biofilms on prosthetic material. Biofilms are bacterial communities adhered to a surface with a self-made extracellular polymeric substance that surrounds resident bacteria. In contrast to planktonic bacteria, bacteria in a biofilm are in an adherent, dormant state and are insensitive to most antibiotics. In addition, bacteria in a biofilm are protected from phagocytic cells of the immune system. Therefore, complete surgical removal and replacement of the prosthetic implant is often necessary to treat this type of infections. Neutrophils play a crucial role in clearing bacterial pathogens. They recognize planktonic bacteria via immunoglobulin (Ig) and complement opsonisation. In this project, we aim to evaluate the role of IgG and complement in the recognition and clearance of staphylococcal biofilms by human neutrophils. Furthermore, we evaluate if monoclonal antibodies (mAbs) targeting biofilm structures can enhance recognition and clearance of staphylococcal biofilms by the human immune system.”

Method

“We produced a set of 20 recombinant mAbs specific for staphylococcal antigens. Using flow cytometry and ELISA-based methods we determined the binding of these mAbs to planktonic staphylococci and in vitro staphylococcal biofilms. Following incubation with IgG/IgM depleted human serum we determined whether mAbs can react with the human complement system after binding to biofilm. Confocal microscopy was used to visualize the location of antibody binding in the biofilm 3D structure.”

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