Visceral adipose tissue activated macrophage content and inflammatory adipokine secretion is higher in pre-eclampsia than in healthy pregnancys

Abstract

Obesity increases pre-eclampsia (PE) risk. Adipose tissue inflammation may contribute to the clinical syndrome of PE. We compared adipose tissue macrophage infiltration and release of pro-inflammatory adipokines in PE and healthy pregnancy. Subcutaneous and visceral adipose tissue biopsies were collected from healthy (n=13) and PE (n=13) mothers. Basal and lipopolysaccharide (LPS) stimulated adipocyte TNFα, IL-6, CCL-2, and CRP release was measured. Adipose tissue cell densities of activated (cfms⁺) and total (CD68⁺) macrophages were determined. In PE only, visceral adipose tissue TNFα release was increased after LPS stimulation (57 [76] versus 81 [97] pg/ml/µg DNA, P=0.030). Basal TNFα release was negatively correlated insulin sensitivity of visceral adipocytes (r = -0.61, P=0.030) in PE. Visceral adipocyte IL-6 release was increased after LPS stimulation in PE only (566 [696] versus 852 [914] pg/ml/µg DNA, P=0.019). Visceral adipocyte CCL-2 basal (67 [61] versus 187 [219] pg/ml/µgDNA, P=0.049) and stimulated (46 [46] versus 224 [271] pg/ml/µg DNA, P=0.003) release was greater than in subcutaneous adipocytes in PE only. In PE, median TNF mRNA expression in visceral adipose tissue was higher than controls (1.94 [1.13-4.14] versus 0.8 [0.00-1.27] TNF/PPIA ratio, P=0.006). In visceral adipose tissue, CSF1R (a marker of activated macrophages) mRNA expression (24.8[11.0] versus 51.0[29.9] CSF1R/PPIA ratio, P=0.011) and activated (cfms+) macrophage count (6.7[2.6] versus 15.2[8.8] % cfms+/adipocyte, P=0.031) were higher in PE than in controls. In conclusion, our study demonstrates dysregulation of inflammatory pathways predominantly in visceral adipose tissue in PE. Inflammation of visceral adipose tissue may mediate many of the adverse metabolic effects associated with PE.

Keywords: adipocytes; adipokines; preeclampsia; pregnancy.

Figure 1. Adipocyte TNFα release

Basal and lipopolysaccahride (LPS) stimulated TNFα (pg/ml/µgDNA) secreted by maternal subcutaneous adipose tissue (SAT) adipocytes and visceral adipose tissue (VAT) adipocytes in control pregnancy (n=13) and in pregnancies complicated by PE (n=13) is shown. Means and standard deviations are presented. *P<0.05 basal versus LPS stimulated TNFα release analyzed by paired t-test on square root transformed data.

Figure 2. Adipocyte IL-6 release

Basal and LPS stimulated IL-6 (pg/ml/µgDNA) secreted by maternal SAT and visceral VAT adipocytes in control pregnancy (n=13) and in pregnancies complicated by PE (n=13) is shown. Means and standard deviations are presented. *P<0.05, **P<0.010, ***P<0.001. Analysis by two sample (PE versus controls) or paired (SAT versus VAT) t-test on log transformed data.

Figure 3. Adipocyte CCL-2 release

Basal and LPS stimulated CCL-2 secreted from maternal SAT and VAT adipocytes in control pregnancy (n=13) and in pregnancies complicated by PE (n=13) is shown. Means and standard deviations are presented. *P<0.05 and **P<0.01 SAT versus VAT using paired t-test on log transformed data.

Figure 4. Adipose tissue macrophage marker messenger RNA expression

Messenger RNA expression of CD68 (n=13) and CSF1R (n=13) relative to PPIA expression in control and PE SAT and VAT is shown. Means and standard deviations are presented. *P<0.05 CSF1R mRNA expression in PE VAT compared with control VAT by two sample t-test on log transformed data.

Figure 5. Adipose tissue macrophage content

SAT and VAT macrophage densities expressed as mean cell count per adipocyte in controls (n=9) and PE (n=9) matched for BMI are shown. Means and standard deviations are presented. *P<0.05 between the mean percentage of VAT cfms⁺/adipocyte in PE compared to controls by two sample t-test on log transformed data.