Molecular pathophysiology of diabetes mellitus during pregnancy with antenatal complications

Abstract

Gestational diabetes mellitus is a daunting problem accompanied by severe fetal development complications and type 2 diabetes mellitus in postpartum. Diagnosis of diabetic conditions occurs only in the second trimester, while associated antenatal complications are typically revealed even later. We acquired an assay of peripheral and cord blood samples of patients with different types of diabetes mellitus who delivered either healthy newborns or associated with fetopathy complications. Obtained data were handled with qualitative and quantitative analysis. Pathways of molecular events involved in diabetes mellitus and fetopathy were reconstructed based on the discovered markers and their quantitative alteration. Plenty of pathways were integrated to differentiate the type of diabetes and to recognize the impact of the diabetic condition on fetal development. The impaired triglycerides transport, glucose uptake, and consequent insulin resistance are mostly affected by faulted lipid metabolism (APOM, APOD, APOH, APOC1) and encouraged by oxidative stress (CP, TF, ORM2) and inflammation (CFH, CFB, CLU) as a secondary response accompanied by changes in matrix architecture (AFM, FBLN1, AMBP). Alterations in proteomes of peripheral and cord blood were expectedly unequal. Both up- and downregulated markers were accommodated in the cast of molecular events interconnected with the lipid metabolism, RXR/PPAR-signaling pathway, and extracellular architecture modulation. The obtained results congregate numerous biological processes to molecular events that underline diabetes during gestation and uncover some critical aspects affecting fetal growth and development.

Figure 1

Matrix of pairwise Kendall' s-tau rank correlation between the studied groups. The Kendall-tau correlation coefficient can take values from -1 to 1, where the most negative value reflects a negative correlation between weighted parameters. In contrast, the most positive values reflect positive intergroup correlation. The obtained Kendall’s-tau correlation coefficient in the M-series (A) of peripheral blood samples ranged between − 0.757 (pair of G07M and G06M groups) to 0.938 (between G09M and G02M groups). In the C-series (B) of umbilical blood samples the studied groups the Kendall’s-tau correlation touched between − 0.554 (pair of G06P and G02P groups) and 0.896 (pair of G07P and G09P groups).

Figure 2

Heatmap of the differentially altered proteome implicated in the initiation and progression of the diabetic condition during gestation and its impact on dire antenatal consequences. (A) In the M-series (peripheral blood samples) of study groups, the differential semi-quantitative map includes proteins that differ between groups from 2.5 to 0.5-fold changes (at p < 0.005). The hierarchical clustering demonstrates the closest relation between groups of GDM (G01M-G04P) based on the dynamic changes of the most abundant proteins. Groups of T2DM (G07M and G09M) are the most detached due to the contrast dynamic of proteins involved in hemostasis maintenance and the complement cascade. The sparsely integrated group is G06M (obesity), demonstrating a specific increase of major plasma transport proteins. (B) The C-series (umbilical blood samples) study groups the presented differential semi-quantitative map includes proteins that differ between groups from 2.5 to 0.5-fold changes (at p < 0.005) while a portion consisted of 22 proteins with p < 0.01 was excluded from this map. The hierarchical clustering demonstrates that the control group (G05P) appears to be the most detached group characterized by a significant decrease of the vast fraction of proteins under consideration. At the same time, some groups of GDM (G01-G03P) are closely related to T2DM patients who delivered newborns with signs of DF (G09P) by similar dynamic among proteins involved in the lipid transport and inflammatory condition. In contrast, other GDM group (G04P) was outlined and behaved in a counter wise fashion to the obesity group (G06P) and T2DM patients with the normal outcome of pregnancy (G10P).

Figure 3

Reconstruction of the proteomic map of peripheral blood that reflects the molecular processes commonly involved in the progression of GDM, T1DM, and T2DM and accompanying the complication of fetal development. The impaired glucose uptake and consequent insulin resistance is mostly affected by disturbance of lipid transport and faulted lipid metabolism in which apolipoproteins play a crucial role. In diabetic condition, glucose utilization is shifted to non-oxidative glycolysis which is rendered in the enhanced lactate and pyruvate interconversion leading to tissue and endothelium damage, and to de novo lipids synthesis due to the corrupted insulin clearance. This can be detected in the imbalance of VLDL, HDL, and LDL maintenance and progression of inflammatory-related processes enhanced by the oxidative properties of CP. The level of CP may also increase due to the gained production of estrogens during gestation. The developing insulin resistance creates a risk of blood glucose accumulation, its autooxidation, protein glycation, and oxidative stress. This leads to further deployment of the pro-inflammatory condition in the way of HIF-1 induced activation of TF through TRF1 receptors up to the late antenatal age. The positive regulation loop is accomplished through the enhanced synthesis of estrogens, which upregulate CP. The effect of consequent tissue damage and inflammation due to oxidative stress caused, partially, by glucose autooxidation is enhanced by the coupled activation of KNG1 and PLG positively regulated by AGT. On the other hand, the enhanced expression of AGT1 brings to an anti-inflammatory effect through functional interaction with F2. In general, these interactions place the hemostasis at a higher risk of thrombosis, which is also enhanced by the action of AMBP inhibiting PLG. Positive feedback is accomplished through the increased APOH, which activates the LPL powering generation of fatty acdis (FA) from triglycerides (TG). In turn, the latter closes the loop with PPAR receptors guiding the lipid metabolism and glucose uptake.

Figure 4

Reconstructed proteomic map in umbilical blood for molecular processes putatively involved in the complicated fetal growth and development in patients with signs of T1DM, T2DM, and GDM. The metabolism of lipids is regulated by ligands of PPAR-α receptors targeting expression of apolipoproteins. In turn, FA through activation of PPAR-γ receptors and 9-cis-retinoic acid transported by APOM to RXR-receptors may regulate expression of PEPCK and AQ7 genes involved in gaining the gluconeogenesis and, consequently, enhance expression of glycogenic genes. Unlike the T2DM patients, when the increasing anaerobic glycolysis is prevalent, in T1DM patients, the origination of oxidative stress is partially evoked by the increased oxidative glycolysis rate. Both processes disbalance lipids metabolism and call insulin resistance in different ways. Impairments of lipids metabolism are also evinced in the growth of AFM abundance that transports vitamin E and lipophilic molecules under conditions of deficient lipids transport. Besides, AFM is positively regulated by ORM2, which is responded to the progression of inflammation conditions caused by the CP-enhanced oxidative stress and supported by the concomitant processes in the coagulation system. In hemostasis, KNG1 is increased, and concurrent action of PLG and HRG for binding with fibrin significantly retards fibrinolysis and enhances the risk of thrombi formation. Malfunction of hemostasis is also reflected in re-arrangements of the extracellular matrix which are accomplished through the functional complex FBLN1 and APOA1 mediating the activation of TGF-β signaling. Although estrogens negatively regulate APOD, its abundance is increased due to DHEA action on the PPAR receptors as a defense mechanism in response to oxidative stress supported by CP and complement system escalation.