Proteomic Analysis of Implant Surfaces in Athroplasty Failure - PROJECT SUMMARY Our team has developed a strategy that samples materials on surfaces of removed orthopedic implants using sonication and shown that the derived biofilm-sampling “sonicate fluids” have the highest yield of any specimen type for microbial detection and can furthermore be used to assess host response at implant surfaces. While assessment of host response has been clinically leveraged to differentiate infected from non-infected orthopedic implants, host-based approaches deployed to date have been simplistic, detecting alpha-defensin or profiling neutrophil numbers, for example, with none defining the microbiology of infected arthroplasties or underlying etiologies of non-infectious arthroplasty failure. We hypothesize that, beyond differentiating infectious from non-infectious arthroplasty failure, capturing host response in sonicate fluid using a proteomic approach will discern microbial etiologies of periprosthetic joint infection and individual causes of non- infectious arthroplasty failure. Given that detection of causative organisms in periprosthetic joint infection and definition individual causes of non-infectious arthroplasty failure, needed to direct management, are not universally realized with extant diagnostic approaches, this will be clinically useful. We propose the first-ever global, unbiased proteomic analysis of sonicate fluid, assessing in vivo human immune response to infectious compared to non-infectious arthroplasty failure and subsets thereof. We further propose an unbiased global analysis of microbial proteins in sonicate fluid in periprosthetic joint infection. Sonicate fluid has been shown in preliminary work to be suitable for the proposed proteomic analyses. Sonicate fluid from failed total knee arthroplasties will be studied using the new technology of liquid chromatography tandem mass spectrometry to determine whether host proteomic analysis can differentiate Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Enterococcus faecalis and Streptococcus agalactiae periprosthetic joint infection, and non-infectious arthroplasty failure subsets of aseptic loosening, periprosthetic fracture, instability, and osteolysis/adverse tissue reaction. In addition to mass spectrometry, a complementary next generation sequencing-based proximity extension assay approach that measures levels of 3,072 cytokines and other host proteins will be used to measure low abundance human proteins missed using mass spectrometry alone, allowing examination of host response in even greater detail. Finally, microbial proteomic analysis of sonicate fluid from patients with periprosthetic joint infection will be performed, to determine whether microbial proteomic analysis can differentiate S. aureus, S. epidermidis, S. lugdunensis, E. faecalis and S. agalactiae infections.
