Progesterone-induced blocking factor affects the expression of Hsp70 family members and TLR4 at normal early pregnancy implantation

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Heat shock proteins (hsps) are induced by a range of cellular insults including heat shock, oxidative stress and ischaemia–reperfusion injury, protecting cells from injury and promoting refolding of denatured proteins. Necrosis of various cell types could be a potential source of extracellular hsps. Released in the extracellular space hsps by themselves and in the complex with peptides become forceful immunogens. They bind to surface receptors on antigen presenting cells, stimulating proinflammatory response, which might be harmful in pregnancy. The aim of our study was to evaluate the distribution of Hsp70 family members and its receptor TLR4 at the first trimester of normal pregnancy decidua, as well as, to investigate the influence of progesterone's mediator progesterone inducing blocking factor (PIBF) on the protein and gene levels of Hsp70 and TLR4 in decidual mononuclear cells suspensions (DMC) isolated from normal first trimester pregnancy decidua in vitro. MATERIAL AND METHODS: Immunohistology and immunofluorescence were used to detect presence and localization of Hsp70, Hsc70and TLR4 in paraffin embedded tissue sections at the infiltration site of first trimester pregnancy decidua. Site of implantation was visualized by cytokeratin labelling. The expression of TLR4 was investigated with flow cytometry in leucocytes subpopulation within DMC suspension. RT-qPCR was used for mRNA detection of Hsp70 and TLR4 in DMC. Possible interaction of Hsp70 and TLR4 receptor on decidual CD1a+ dendritic cells was investigated by binding assay. RESULTS: Hsc70 is widely distributed and more intensively labelled in cells at the infiltration site when compared to Hsp70. TLR4 is also abundantly expressed in cells. The treatment of DMC with PIBF decreased the frequency of TLR4 expressing T cells. PIBF in vitro diminished Hsp70 and TLR4 gene expression in DMC. Hsp70 specifically on a dose dependent manner binds to TLR4 on decidual CD1a+ dendritic cells. CONCLUSION: PIBF affects the expression of Hsp70, Hsc70 and TLR4 at both mRNA and protein levels controlling that way the initiation of the immune response mediated by hsps in normal early pregnancy decidua.