Data_Sheet_1_Radioimmunotherapy combating biofilm-associated infection in vitro.docx

BackgroundAddressing prosthetic joint infections poses a significant challenge within orthopedic surgery, marked by elevated morbidity and mortality rates. The presence of biofilms and infections attributed to Staphylococcus aureus (S. aureus) further complicates the scenario.
ObjectiveTo investigate the potential of radioimmunotherapy as an innovative intervention to tackle biofilm-associated infections.
MethodsOur methodology involved employing specific monoclonal antibodies 4497-IgG1, designed for targeting wall teichoic acids found on S. aureus and its biofilm. These antibodies were linked with radionuclides actinium-225 (225Ac) and lutetium-177 (177Lu) using DOTA as a chelator. Following this, we evaluated the susceptibility of S. aureus and its biofilm to radioimmunotherapy in vitro, assessing bacterial viability and metabolic activity via colony-forming unit enumeration and xylenol tetrazolium assays.
ResultsBoth [225Ac]4497-IgG1 and [177Lu]4497-IgG1 exhibited a noteworthy dose-dependent reduction in S. aureus in planktonic cultures and biofilms over a 96-h exposure period, compared to non-specific antibody control groups. Specifically, doses of 7.4 kBq and 7.4 MBq of [225Ac]4497-IgG1 and [177Lu]4497-IgG1 resulted in a four-log reduction in planktonic bacterial counts. Within biofilms, 14.8 kBq of [225Ac]4497-IgG1 and 14.8 Mbq [177Lu]4497-IgG1 led to reductions of two and four logs, respectively.
ConclusionOur findings underscore the effectiveness of [225Ac]4497-IgG1 and [177Lu]4497-IgG1 antibodies in exerting dose-dependent bactericidal effects against planktonic S. aureus and biofilms in vitro. This suggests that radioimmunotherapy might serve as a promising targeted treatment approach for combating S. aureus and its biofilm.

背景：人工关节感染的诊疗是骨科手术领域面临的重大挑战，其伴随的发病率与死亡率均处于较高水平。由金黄色葡萄球菌（Staphylococcus aureus, S. aureus）引发的生物膜相关感染，进一步加剧了该临床难题的复杂性。
目的：探讨放射免疫疗法作为创新性干预手段治疗生物膜相关感染的应用潜力。
方法：本研究采用靶向金黄色葡萄球菌及其生物膜表面壁磷壁酸的特异性单克隆抗体4497-IgG1，以DOTA作为螯合剂，将该抗体分别与放射性核素锕-225（actinium-225, 225Ac）和镥-177（lutetium-177, 177Lu）进行偶联。随后通过体外实验评估金黄色葡萄球菌及其生物膜对放射免疫疗法的敏感性，采用菌落形成单位计数法与二甲酚四氮唑（xylenol tetrazolium）实验分别检测细菌存活率与代谢活性。
结果：与非特异性抗体对照组相比，[225Ac]4497-IgG1与[177Lu]4497-IgG1在96小时的暴露周期内，对浮游培养状态与生物膜中的金黄色葡萄球菌均展现出显著的剂量依赖性杀伤效果。具体而言，给予7.4 kBq的[225Ac]4497-IgG1与7.4 MBq的[177Lu]4497-IgG1，可使浮游细菌数量降低4个对数级。在生物膜模型中，14.8 kBq的[225Ac]4497-IgG1与14.8 MBq的[177Lu]4497-IgG1分别可使细菌数量降低2个与4个对数级。
结论：本研究结果证实，[225Ac]4497-IgG1与[177Lu]4497-IgG1抗体在体外实验中对浮游态金黄色葡萄球菌及生物膜均具有剂量依赖性的杀菌效果。这表明放射免疫疗法有望成为对抗金黄色葡萄球菌及其生物膜感染的一种极具前景的靶向治疗策略。