Highly Conserved but Activation-Dependent CCR5, CCR6, and CXCR4 Chemokine Receptor Expression and Trophoblast-Mediated Cytokine Profile of Peripheral Gamma-Delta T Cells During Early Human Pregnancy

Pregnancy requires balanced maternal immune regulation for healthy fetal development, in which γδT cells contribute at the feto-maternal interface; however, mechanisms guiding decidual γδT-cell accumulation remain unclear. We analyzed chemokine receptor (ChR) expression (C-C motif ChR [CCR]5, CCR6, and C-X-C motif ChR [CXCR]4) and cytokine profiles of peripheral γδT cells from first-trimester pregnant and nonpregnant women by multicolor flow cytometry under baseline and antigen-independent activation, while cytokine modulation was assessed in isolated γδT cells co-cultured with trophoblasts using cytometric bead array (CBA). While the frequency of ChR-expressing γδTCR+ cells was largely preserved, CCR6 and CXCR4 expression intensities were slightly elevated during pregnancy. Although single ChR expression did not differ between conventional and natural killer (NK)-like γδT cell subsets, the proportions of some ChR co-expressing populations were slightly but significantly higher among NK-like γδT cells. Within the observed co-expression patterns, CCR5/CCR6 was the most frequent combination on γδT cell subsets. Furthermore, different stimulation models differently shaped ChR expression on conventional γδT cells, with physiological activation maintaining CCR5+ dominance alongside elevated CXCR4+ cell ratios, whereas PMA/Ionomycin stimulation was characterized by a predominance of CXCR4+ cells and a low proportion of CCR5+ cells. In terms of cytokine production γδT cells exhibited a broad Th1-like cytokine profile dominated by IL-2, TNF-α, and IFN-γ, with modest reductions in TNF-α and IFN-γ during pregnancy. Trophoblast contact further attenuated this response by inhibiting IL-2, TNF-α, and IL-17A release, while markedly enhancing IL-6 production. Our findings suggest that γδT cell subsets slightly differ in ChR co-expression patterns, and ChRs are differentially regulated by distinct activation processes. The modest differences observed during first-trimester pregnancy indicate a conserved migratory capacity, with pregnancy-specific migratory phenotypes likely shaped at the materno-fetal interface. Additionally, γδT cells exhibited an inflammatory cytokine milieu that was modulated upon trophoblast contact, which may contribute to trophoblast-mediated immune adaptations during human pregnancy.