Gene expression profiling of peripheral blood mononuclear cells in endometriosis identifies genes altered in non-gynaecologic chronic inflammatory diseases.

Background: Pelvic inflammatory phenomena have been suggested as critical players in the natural history of endometriosis. However, to what extent these events could affect the systemic immunologic status remains to be clarified. Here, we compared the gene expression profile in peripheral blood mononuclear cells from endometriosis patients in the severe diseased stage with the profile after a conventional surgical treatment for removal of endometriotic lesions and adhesions.

Methods: Microarray analysis included four patients suffering from severe endometriosis in which blood samples were obtained few days before the surgical intervention and again 6 months later. Real-time quantitative PCR analyses on a larger population were performed for some genes up-regulated in the diseased stage in a case-control approach.

Results: Among the 17,665 probe signals detected in the microarray, n = 26 genes resulted up-regulated and n = 15 were down-regulated in the diseased stage. Five genes up-regulated in diseased stage (FBJ Murine osteosarcoma viral oncogene homolog gene, dual specificity phosphatase 1, pre-B-cell colony enhancing factor 1, adrenomedullin and S100 calcium binding protein P) were exactly those shown as up-regulated in peripheral leukocytes of psoriasis patients in a very similar study design (diseased versus 'cured' stage), with a 5.2 × 10(-11) hypergeometric probability that this event could occur by chance.

Conclusions: Endometriosis induces the expression of genes in peripheral leukocytes already identified in non-gynaecologic chronic inflammatory diseases, thus revealing the disease as a local affliction with relevant consequences at the systemic level. Although the commonality of gene expression with other inflammatory diseases prevents the use of these genes as non-invasive diagnostic markers, from a clinical standpoint, the idea that the surgical intervention may reduce the expression of peripheral leukocyte genes represents a novel finding.