Gene expression profiling in wear-particle induced and infectious endoprosthesis loosening. Homo sapiens

The aim of the study was to identify markers for the early diagnosis of endoprosthesis loosening, for the differentiation between wear-particle induced and septic loosening, as well as to gather new insights into the pathogenesis. 824 genes were differentially expressed with a fold change greater than 2. Among these were Chitinase 1, CD52, Calpain 3, Apolipoprotein, CD18, Lysyl oxidase, Cathepsin D, E-Cadherin, VE-Cadherin, Nidogen, Angiopoietin 1 and Thrombospondin 2, and the differential expression levels were validated by RT-PCR. The chitinase activity was significantly higher in the blood from patients with wear-particle induced prosthesis loosening (p=0.001). However, using chitinase activity as a marker for early diagnosis, it has a specificity of 83% and a sensitivity of only 52%, due to a high variability both in the disease and in the control group. Keywords: Tissue type comparison, disease state analysis, search for new biomarkers Overall design: Gene expression profiles were generated from 5 periprosthetic membranes of wear-particle induced and 5 of infectious (septic) type using Affymetrix HG U133A oligonucleotide microarrays. The results of selected differentially expressed genes were validated by RT-PCR (n=30). The enzyme activity and the genotype of chitinase-1 were assessed in serum samples from 313 consecutive patients hospitalized for endoprosthesis loosening (n=54) or for other reasons, serving as control subjects (n=259).