Immune Profile of the Normal Maternal-Fetal Interface in Rhesus Macaques and Its Alteration Following Zika Virus Infection

Abstract

The maternal decidua is an immunologically complex environment that balances maintenance of immune tolerance to fetal paternal antigens with protection of the fetus against vertical transmission of maternal pathogens. To better understand host immune determinants of congenital infection at the maternal-fetal tissue interface, we performed a comparative analysis of innate and adaptive immune cell subsets in the peripheral blood and decidua of healthy rhesus macaque pregnancies across all trimesters of gestation and determined changes after Zika virus (ZIKV) infection. Using one 28-color and one 18-color polychromatic flow cytometry panel we simultaneously analyzed the frequency, phenotype, activation status and trafficking properties of αβ T, γδ T, iNKT, regulatory T (Treg), NK cells, B lymphocytes, monocytes, macrophages, and dendritic cells (DC). Decidual leukocytes showed a striking enrichment of activated effector memory and tissue-resident memory CD4+ and CD8+ T lymphocytes, CD4+ Tregs, CD56+ NK cells, CD14+CD16+ monocytes, CD206+ tissue-resident macrophages, and a paucity of B lymphocytes when compared to peripheral blood. t-distributed stochastic neighbor embedding (tSNE) revealed unique populations of decidual NK, T, DC and monocyte/macrophage subsets. Principal component analysis showed distinct spatial localization of decidual and circulating leukocytes contributed by NK and CD8+ T lymphocytes, and separation of decidua based on gestational age contributed by memory CD4+ and CD8+ T lymphocytes. Decidua from 10 ZIKV-infected dams obtained 16-56 days post infection at third (n=9) or second (n=1) trimester showed a significant reduction in frequency of activated, CXCR3+, and/or Granzyme B+ memory CD4+ and CD8+ T lymphocytes and γδ T compared to normal decidua. These data suggest that ZIKV induces local immunosuppression with reduced immune recruitment and impaired cytotoxicity. Our study adds to the immune characterization of the maternal-fetal interface in a translational nonhuman primate model of congenital infection and provides novel insight in to putative mechanisms of vertical transmission.

Decidual leukocytes respond to African lineage Zika virus infection with mild anti-inflammatory changes during acute infection in rhesus macaques

“…These results differ from those previously reported in rhesus macaque decidua at around the same gestational age, where dNKs were found to account for ~70% of all leukocytes ( 43 , 51 ). However, the current findings more closely resemble those recently reported by Moström et al., who also found CD8+ T cells make up the highest percentage of decidual leukocytes in rhesus macaques ( 44 ). This distribution of decidual leukocytes found in our control samples suggests that the composition of rhesus macaque decidual leukocytes at this time in gestation more closely resembles the decidual immune population seen in humans later in gestation ( 47 , 52 , 53 ).…”

“…FlowSOM clustering coupled with t-SNE visualization identified major leukocyte populations: CD8+ Cytotoxic T cells, CD4+ T helper cells, CD4-CD8-(double negative, DN) T cells, CD4+ CD8+ (double positive, DP) T cells, macrophages/monocytes, DCs, innate lymphoid cells (ILCs), and B cells (Figure 1A). We based our annotations on the expression of lineage-defining markers (Table 2, Figure 1B) following previously reported phenotypes (37,(43)(44)(45). To summarize the differences between the PBMCs and the decidua, PCA was performed on the MFI of each marker in each of the eight major leukocyte populations on identically unmixed sample files.…”

“…Ex vivo studies using human decidual explants have shown that ZIKV infection results in pro-inflammatory responses (30, 31). Moström et al evaluated the response to Asian-linage ZIKV infection in vivo in decidua samples from rhesus macaques 16-56 days post infection (44). However, the in vivo acute response to African-lineage ZIKV infection in the decidua remained unknown.…”

Interleukin-10 Delays Viral Clearance in the Placenta and Uterus of Mice With Acute Lymphocytic Choriomeningitis Virus Infection During Pregnancy

“…This state may be one of heightened early activation, which may lead to a state which is like exhaustion, but which can be "cured" by tissue-derived factors when needed to clear viral infections. The concept of a unique intrauterine CD8 T cell phenotype-one that exhibits elements of the "exhaustion-that-can-be-relieved" phenotype is supported by studies in other animal models (87)(88)(89) and in humans (90-92). Our hope is that consideration of this concept can be utilized to develop therapeutic interventions to prevent congenital infection.…”

Tissue-resident immunity in the female and male reproductive tract

“…The expression level of CD1d even increases with progressing gestation [ 101 ]. However, a recent publication questioned the importance of iNKT cell in pregnancy since less than 1% of the CD56 + CD3 + NKT cells are also positive for the iNKT-specific CD1d tetramer [ 102 ]. Despite discussion regarding their actual proportion at the feto-maternal interface, a shift toward a Th1-biased cytokine profile of iNKT cells, including increased TNFα, IFNγ and perforin production, seems to contribute to higher pregnancy loss rates [ 103 , 104 ].…”