Maternal Innate Immune Reprogramming After Complicated Pregnancy

PROBLEM

Preeclampsia (PE) and fetal growth restriction (FGR) are often associated with maternal inflammation and an increased risk of cardiovascular and metabolic disease in the affected mothers. The mechanism responsible for this increased risk of subsequent disease may involve reprogramming of innate immune cells, characterized by epigenetic modifications.

METHOD OF STUDY

Circulating monocytes from women with PE, FGR, or uncomplicated pregnancies (control) were isolated before labor. Cytokine release from monocytes following exposure to lipopolysaccharide (LPS) and the presence of lysine 4-trimethylated histone 3 (H3K4me3) within TNF promoter sequences were evaluated. Single-cell transcriptomic profiles of circulating monocytes from women with PE or uncomplicated pregnancies were assessed.

RESULTS

Monocytes from women with PE or FGR exhibited increased IL-10 secretion and decreased IL-1β and GM-CSF secretion in response to LPS. While TNFα secretion was not significantly different in cultures of control monocytes versus those from complicated pregnancies with or without LPS exposure, monocytes from complicated pregnancies had significantly decreased levels of H3K4me3 associated with TNF promoter sequences. Cluster quantification and pathway analysis of differentially expressed genes revealed an increased proportion of anti-inflammatory myeloid cells and a lower proportion of inflammatory non-classical monocytes among the circulating monocyte population in women with PE.

CONCLUSIONS

Monocytes from women with PE and FGR exhibit an immune tolerance phenotype before initiation of labor. Further investigation is required to determine whether this tolerogenic phenotype persists after the affected pregnancy and contributes to increased risk of subsequent disease.

Utility of peripheral blood monocyte subsets, circulating immune complexes and serum cytokines in assessment of SLE activity: an observational, cross-sectional study

INTRODUCTION

SLE disease measurements by current standards are less than perfect. Monocytes and their subsets are part of innate immunity, and one of our objectives was to look at their role in SLE disease activity. We also looked at the common serum cytokines and the role of circulating immune complex (CIC) estimation in the assessment of disease activity.

METHODS

We conducted a single-centre observational cross-sectional study of SLE patients with active and inactive disease as the comparison arms. Blood samples were collected for (a) peripheral blood monocyte separation and flowcytometric analysis of monocyte subsets based on CD14 and CD16 surface markers, and (b) ELISA for serum cytokines and CIC estimation. Results were analysed in terms of the difference in medians between the active and inactive disease groups using the Mann-Whitney U test (non-normally distributed data).

RESULTS

The absolute monocyte count was lower in the active group than the inactive group (median (IQR) of 329 (228.5) vs. 628 (257)/microliter, p = 0.001). The frequency (%) of the intermediate monocyte subset showed a trend towards an increase in active disease (median (IQR) of 15.10% (9.65) vs. 11.85% (8.00), p = 0.09). It also had a significant positive correlation to the SLEDAI scores (r = 0.33, p = 0.046). The mean fluorescence intensity (MFI) of CD163, expressed primarily by intermediate subsets, was increased, and CD11c MFI was reduced in active disease. Serum TNF-a level was elevated in active disease (median (IQR) of 38 (48.5) pg/ml vs. 9 (48.5) pg/ml, p = 0.042). CIC ELISA at an optimal cut-off of 10 meq/ml provided an area under the curve (AUC) of 0.85 for detecting active SLE.

CONCLUSION

Peripheral blood monocytes are depleted in active disease. The intermediate monocyte subset may have a role in disease activity. TNF-alpha correlated modestly with disease activity. CIC estimation by ELISA may be used in addition to or as an alternative to current standards of laboratory tests for the serological assessment of activity.

Maternal body mass index is associated with an altered immunological profile at 28 weeks of gestation

Healthy pregnancy is accompanied by various immunological and metabolic adaptations. Maternal obesity has been implicated in adverse pregnancy outcomes such as miscarriage, preeclampsia, and gestational diabetes mellitus (GDM), while posing a risk to the neonate. There is a lack of knowledge surrounding obesity and the maternal immune system. The objective of this study was to consider if immunological changes in pregnancy are influenced by maternal obesity. Peripheral blood was collected from fasted GDM-negative pregnant women at 26-28 weeks of gestation. Analysis was done using immunoassay, flow cytometry, bioenergetics analysis, and cell culture. The plasma profile was significantly altered with increasing BMI, specifically leptin (r = 0.7635), MCP-1 (r = 0.3024), and IL-6 (r = 0.4985). Circulating leukocyte populations were also affected with changes in the relative abundance of intermediate monocytes (r = -0.2394), CD4:CD8 T-cell ratios (r = 0.2789), and NKT cells (r = -0.2842). Monocytes analysed in more detail revealed elevated CCR2 expression and decreased mitochondrial content with increased BMI. However, LPS-stimulated cytokine production and bioenergetic profile of PBMCs were not affected by maternal BMI. The Th profile skews towards Th17 with increasing BMI; Th2 (r = -0.3202) and Th9 (r = -0.3205) cells were diminished in maternal obesity, and CytoStim™-stimulation exacerbates IL-6 (r = 0.4166), IL-17A (r = 0.2753), IL-17F (r = 0.2973), and IL-22 (r = 0.2257) production with BMI, while decreasing IL-4 (r = -0.2806). Maternal obesity during pregnancy creates an inflammatory microenvironment. Successful pregnancy requires Th2-biased responses yet increasing maternal BMI favours a Th17 response that could be detrimental to pregnancy. Further research should investigate key populations of cells identified here to further understand the immunological challenges that beset pregnant women with obesity.