Hypoxia-inducible factor 1 (HIF-1) may play a role in mammary gland development, milk production and secretion in mammals. Due to the limited number of scientific reports on the expression of HIF genes in colostrum cells, it was decided to examine the expression of HIF1A, HIF3A and EPAS1 in the these cells, collected from 35 patients who voluntarily agreed to provide their biological material for research, were informed about the purpose of the study and signed a consent to participate in it. The expression of HIF genes was assessed using qPCR. Additionally, the influence of clinical parameters (method of delivery, occurrence of stillbirths in previous pregnancies, BMI level before pregnancy and at the moment of delivery, presence of hypertension during pregnancy, presence of Escherichia coli in vaginal culture, iron supplement and heparin intake during pregnancy) on the gene expression was assessed, revealing statistically significant correlations. The expression of HIF1A was 3.5-fold higher in the case of patients with the presence of E. coli in vaginal culture (p = 0.041) and 2.5 times higher (p = 0.031) in samples from women who used heparin during pregnancy. Approximately 1.7-fold higher expression of the EPAS1 was observed in women who did not supplement iron during pregnancy (p = 0.046). To our knowledge, these are the first studies showing the relationship between HIF expression in cells from breast milk and the method of delivery and health condition of women giving birth. The assessment of HIF expression requires deeper examination in a larger study group, and the results of further studies will allow to determine whether HIF can become biomarkers in pregnancy pathology states.

Tumor necrosis factor alpha-stimulated protein 6 (TSG-6) is a potent anti-inflammatory mediator secreted by mesenchymal stem cells (MSCs). In human milk (HM), these cells (human milk mesenchymal stem cells, HM-MSCs) contribute to postnatal programming of the neonatal gastrointestinal immune axis. This study assessed how maternal gestational hypertension and maternal age affect the cytoprotective TSG-6 pool and its associated immunomodulatory microRNA signature in early milk. Early colostrum, 2–4 days postpartum, from healthy mothers and hypertensive patients was analyzed. TSG-6 gene expression in the heterogeneous milk cellular fraction containing HM-MSCs and TSG-6 protein concentration in whole milk were determined using quantitative polymerase chain reaction (qPCR) and Enzyme-Linked Immunosorbent Assay (ELISA), respectively. Comprehensive multivariable General Linear Models (GLMs) were used to adjust for potential confounding variables, including pre-pregnancy Body Mass Index (BMI), gestational age (GA), and gestational diabetes. Additionally, TSG-6 levels were correlated with fetal cord blood gas parameters and previously profiled microRNAs in the cellular fraction. GLM analysis revealed that gestational hypertension remained significantly associated with reduced TSG-6 gene expression in the cellular fraction and total TSG-6 protein concentration in whole milk, regardless of pre-pregnancy BMI or metabolic comorbidities. In healthy pregnancies, exploratory analyses suggested that TSG-6 levels correlated positively with optimal fetal metabolic status (cord blood pH). Importantly, TSG-6 expression showed a strong positive correlation with a signature of immunomodulatory microRNAs (miR) (miR-155-5p, miR-21-3p, miR-126-3p). These microRNAs were concurrently downregulated in the hypertensive group; however, because all hypertensive participants received methyldopa, the independent contributions of hypertension and antihypertensive treatment to these changes cannot be distinguished. Gestational hypertension independently reduces the anti-inflammatory TSG-6 in early breast milk. The concomitant reduction in TSG-6 and its correlated microRNA co-expression pattern indicates an altered immunomodulatory profile within the mammary gland during lactation. We hypothesize that these changes might alter the local immunomodulatory properties of milk in the neonatal gastrointestinal tract. However, because no functional in vitro or in vivo assays were performed, this remains a purely theoretical implication that requires future experimental validation.