Chronic histiocytic intervillositis of the placenta (CHI) is a rare and potentially recurrent disease. Characteristically it shows accumulation of CD68+ cells in the intervillous space but no destructive tissue infiltration. An immunopathological background is likely but it is unknown what attracts circulating monocytes to the placenta.
Methods: We analysed the expression profile of 102 inflammation- and angiogenesis-associated genes with real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in 16 placentas: CHI (n = 5) and, as controls, villitis of unknown aetiology (VUE, n = 4) and normal placenta (n = 7).
Results: Compared to controls, CHI had significantly higher levels of matrix metallopeptidase 9 (MMP9) and transforming growth factor, beta receptor 1 (TGFBR1). MMP14 was lower in VUE than CHI (p < 0.05) and controls (not significant). Chemokine (C-X-C motif) ligand 9 (CXCL9), CXCL12, chemokine (C-C motif) ligand 5 (CCL5) and TIMP metallopeptidase inhibitor 1 (TIMP1) were significantly higher in VUE versus controls but not deregulated in CHI. The expression profile could not clearly discriminate CHI from VUE or controls but a tendency for grouping of massive CHI was found. Angiogenesis-associated factors were not deregulated in CHI.
Conclusion: The discrepancy of massive histiocytic accumulation and the lack of striking up-regulation of cytokines might be the basis of the non-destructive behaviour of the histiocytes in CHI.
Keywords: Cytokine; chemokine; chronic histiocytic intervillositis; histiocyte; massive perivillous histiocytosis; monocyte; placenta pathology.