Detection of intra-amniotic infection in a rabbit model by proteomics-based amniotic fluid analysis

Objective This study was undertaken to identify intra-amniotic infection caused by several different organisms in a rabbit model by using proteomics. Study design Twenty infected and 18 uninfected amniotic fluid samples were subjected to proteomic analysis by surface-enhanced laser desorption ionization (SELDI-TOF, Ciphergen Biosystems, Fremont, Calif), 1- and 2-dimensional gel electrophoresis, and tandem mass spectrometry (MS/MS). Results Detailed SELDI-TOF spectra revealed a constitutive 4.0 kd peak in all animals. Infected samples also displayed a signature double peak at 3.6 kd. A SELDI-TOF signature profile for intra-amniotic infection predicted positive amniotic fluid and/or fetal cultures with a sensitivity of 90% and specificity of 83%. Similar proteomic profiles were obtained regardless of the infecting organism. The 3.6 kd peak appeared to contain rabbit calgranulin C and rabbit calcyclin, members of the S100 family of calcium binding proteins. Conclusion Amniotic fluid proteomic analysis was able to detect intra-amniotic infection in this experimental rabbit model. S100 proteins may be involved in the host inflammatory response to intra-amniotic infection.