Serum Macrophage Colony-Stimulating Factor Relates to the Severity and the Pregnancy Outcomes in Hypertensive Disorders Complicating Pregnancy Open Access

Hypertensive disorders complicating pregnancy (HDCP) are a unique and dangerous complication of pregnancy [1]. HDCP can lead to serious complications such as pulmonary edema, placental abruption, renal failure, liver failure, disseminated intravascular coagulation, and stroke in pregnant women [2, 3]. Treatment options for HDCP are limited, and the only effective treatment is extraction of the fetus and placenta [4]. Therefore, the prevention and prediction of hypertension in pregnancy is particularly important.

Macrophage colony-stimulating factor (M-CSF) is an inflammatory mediator that can promote the release of various inflammatory cytokines [5]. M-CSF has been shown to play an important role in the regulation of placental development and function [6, 7]. In pathological pregnancies, M-CSF can stimulate the release of various cytokines and cytotoxic substances, resulting in local vascular endothelial structure and function damage [8]. M-CSF triggers the spasm of arterioles and increases vascular permeability, leading to complications such as gestational hypertension (GH) and preeclampsia [9]. Disease stress during pregnancy, encompassing conditions like gestational diabetes, preeclampsia, infections, or autoimmune disorders, can disrupt the typical dynamics of M-CSF [10]. Inflammatory conditions such as infections or autoimmune diseases can provoke an abnormal immune response, leading to irregular production of M-CSF, which in turn may skew macrophage function toward pro-inflammatory phenotypes, potentially resulting in tissue damage or pregnancy complications [6, 11]. Preeclampsia, marked by high blood pressure and proteinuria, is linked to immune irregularities and impaired endothelial function [1]. Research suggests possible changes in M-CSF levels, but more exploration is required to understand the precise mechanisms and consequences [12].

This study recruited 180 HDCP patients who established files and kept blood samples in our hospital from January 1, 2021, to January 1, 2023. In addition, 120 normal pregnant women with matched gestational age were selected as the control group. HDCP patients were followed up for 6 months. HDCP patients were divided into a “Good outcomes group” and “Poor outcomes group” according to pregnancy outcomes. All patients in this study were of Han nationality. The study was approved by the Ethics Committee of Changchun University of Chinese Medicine Affiliated Hospital, and written informed consent was obtained from the participants.

Inclusion criteria for the HDCP group were pregnant women with HDCP diagnosed according to the diagnostic criteria; age more than 18 years; singleton pregnancy; the patients who established antenatal registration in the obstetrics department of our hospital and gave birth in our hospital. Inclusion criteria for the normal pregnant women group were pregnant women without HDCP; age more than 18 years; singleton pregnancy; patients who established antenatal registration in the obstetrics department of our hospital and gave birth in our hospital. Exclusion criteria were prepregnancy hypertension; multiple pregnancies; patients with diabetes, cerebrovascular, severe liver, and kidney insufficiency, acute and chronic injuries, infection, rheumatism, rheumatoid and other immune system-related diseases.

The diagnostic, screening, and exclusion criteria for HDCP in this study were based on the guidelines established by the American College of Obstetricians and Gynecologists (ACOG) in 2013. Diagnosis of severe preeclampsia (sPE) was predicated upon the aforementioned criteria of preeclampsia along with the presence of any of the following symptoms: 1. systolic blood pressure (SBP) ≥160 mm Hg or diastolic blood pressure (DBP) ≥110 mm Hg, measured at 4-h intervals, with the patient in a supine position and excluding prior antihypertensive drug usage; 2. thrombocytopenia, defined as platelet count <100,000/μL; 3. abnormal liver function, characterized by elevated transaminase levels (more than twice the normal value) and persistent severe pain in the right upper abdomen or subdiaphragmatic region; 4. progressive renal dysfunction, indicated by a serum creatinine level >1.1 mg/dL or a doubling in serum creatinine in the absence of other renal pathologies; 5. pulmonary edema; 6. incipient cerebral damage or visual impairment. Patients were categorized into three groups based on these criteria: 79 cases (43.9%) of isolated pregnancy-induced hypertension, 58 cases (32.2%) of mild preeclampsia (mPE), and 43 cases (23.9%) of sPE.

Sera from subjects in the first trimester were tested by enzyme-linked immunosorbent assay (EH0014, Wuhan FineTest Co.) for the estimation of M-CSF levels. Serum was tested when the subjects were diagnosed or included in the study. The concentrations of IL-6 and TNF-α in the serum were detected by corresponding enzyme-linked immunosorbent assay kits (Wuhan FineTest).

The “poor outcomes” defined in this study mainly include prematurity, fetal growth restriction, fetal distress, postpartum hemorrhage, neonatal asphyxia, neonatal mortality, premature rupture of membranes, placental abruption.

SPSS 25.0 was used for data analysis, the Kolmogorov-Smirnov (K-S) method was used to test the goodness of fit of the measurement data, and the homogeneity of variance was tested by the Levene method. One-way analysis of variance was used for comparison between multiple groups, LSD t test was used for pairwise comparison between groups, and independent sample t test was used for comparison between two groups. Enumeration data expressed as rate (%) were analyzed by χ² test. Correlation analysis was performed by unconditional logistic regression analysis, and stepwise analysis was performed by the Wald method. All statistical tests were two-sided, test level α = 0.05.

Table 1 presents the demographic and clinical features of pregnant women with HDCP compared to those with normal pregnancy (NP). The study included 120 women with NP and 180 women with HDCP. The mean maternal age was 28.67 years (±4.31) in the NP group and 29.15 years (±4.14) in the HDCP group. The difference in maternal age between the two groups was not statistically significant (p = 0.281). Women in the NP group were diagnosed or enrolled at approximately 33.17 weeks (±2.19) of gestation, while women in the HDCP group were diagnosed or enrolled at around 32.91 weeks (±2.84) of gestation. The difference in gestational weeks between the two groups was not statistically significant (p = 0.493). The difference in BMI before pregnancy between the two groups was not statistically significant (p = 0.092). The presence of proteinuria, measured in milligrams per 24 h, showed a substantial difference between the two groups. Women with HDCP had significantly higher proteinuria levels (460.78 ± 343.41 mg/24 h) compared to women with NP (42.84 ± 9.95 mg/24 h). The difference in proteinuria between the two groups was highly significant (p < 0.001). SBP at diagnosis or enrollment was significantly higher in the HDCP group (147.72 ± 13.87 mm Hg) compared to the NP group (112.17 ± 9.48 mm Hg). The difference in SBP between the two groups was highly significant (p < 0.001). DBP at diagnosis or enrollment was also significantly higher in the HDCP group (107.38 ± 10.12 mm Hg) compared to the NP group (79.05 ± 6.82 mm Hg). The difference in DBP between the two groups was highly significant (p < 0.001). In summary, pregnant women with HDCP exhibited significantly higher levels of proteinuria, SBP, and DBP compared to those with NP. However, there were no significant differences in maternal age, gestational weeks at diagnosis/enrollment, or BMI before pregnancy between the two groups.

Women with HDCP were categorized into different clinical classifications: GH (79 [43.9%] of the HDCP cases were classified as having GH), mPE (58 women [32.2%] were diagnosed with mPE), sPE (43 women [23.9%] were identified as having sPE). The study also examined various pregnancy outcomes among women with HDCP; these included prematurity (51 cases [28.3%]), fetal growth restriction (19 cases [10.6%]), fetal distress (22 cases [12.2%]), postpartum hemorrhage (13 cases [7.2%]), neonatal asphyxia (4 cases [7.8%]), neonatal mortality (3 cases [1.7%]), premature rupture of membranes (17 cases [9.4%]), and placental abruption (8 cases [4.4%]). A total of 87 cases (48.3%) among women with HDCP experienced poor outcomes. These poor outcomes were a combination of the aforementioned pregnancy complications. In summary, the majority of women with HDCP in this study were classified as having GH, followed by mPE and sPE. The pregnant outcomes among women with HDCP included prematurity, fetal growth restriction, fetal distress, postpartum hemorrhage, neonatal asphyxia, neonatal mortality, premature rupture of membranes, and placental abruption. Overall, almost half of the cases resulted in poor outcomes.

Figure 1 depicts the results of the analysis related to serum M-CSF levels in pregnant women with HDCP and NP, as well as the predictive values of serum M-CSF for HDCP and its comparison among different HDCP subgroups. The level of M-CSF in the serum of HDCP patients in the first trimester (11–13+6 weeks) was significantly higher than that of normal pregnant women (Fig. 1a). Similarly, levels of M-CSF in HDCP patients at diagnosis were also significantly higher than those in normal pregnant women (Fig. S1a). To analyze the predictive value of serum M-CSF level for HDCP in the first trimester (11–13+6 weeks), the ROC method was used. The sensitivity was 72.78%. The specificity was 80.83%. The cutoff value was 484.13 pg/mL. AUC was 0.83 (Fig. 1b). The false-positive rate was calculated as follows: 100%–80.83% = 19.17%. Finally, the M-CSF levels in patients were compared among the three subgroups of isolated GH (n = 79, 43.9%) group, mPE (n = 58, 32.2%) group, and sPE (n = 43, 23.9%) group. It can be seen that as the severity of disease increases, the concentration of M-CSF also becomes higher (Fig. 1c).

The correlation of serum M-CSF level with 24-h proteinuria and SBP at the time of diagnosis was analyzed in 180 HDCP patients who met the criteria in the first trimester (11–13+6 weeks). The level of serum M-CSF in the first trimester was significantly positively correlated with 24-h proteinuria and SBP at the time of diagnosis (Fig. 2a, b). Intriguingly, our study also demonstrated that the serum M-CSF levels were upregulated at the third trimester compared to the first trimester in both NP and HDCP groups (online suppl. Fig. S1B and C; for all online suppl. material, see https://doi.org/10.1159/000539619).

We further analyzed the serum levels of TNF-α (Fig. 3a) and IL-6 (Fig. 3b) at diagnosis among GH (n = 79), mPE (n = 58), and sPE (n = 43) groups. The levels of TNF-α and IL-6 became higher when preeclampsia became more severe. Furthermore, our data showed that there was a significant positive correlation between serum M-CSF levels in the first trimester and the levels of inflammatory factors in HDCP patients at the time of diagnosis (Fig. 3c, d). Moreover, the TNF-α levels in the serum of HDCP patients were higher than those in normal pregnancies in the first trimester (online suppl. Fig. S1D). However, there was no significant difference between normal pregnancies in the third trimester and the first trimester (online suppl. Fig. S1E), while in HDCP patients, serum TNF-α levels were significantly higher at the time of diagnosis than in the first trimester (online suppl. Fig. S1F).

The pregnancy outcomes of HDCP patients were followed up. The complications related to adverse outcomes are shown in Table 2. Among the 180 HDCP patients, 87 patients had adverse pregnancy outcomes, accounting for 48.3%. The differences in serum M-CSF levels in the first trimester (11–13+6 weeks) of the two groups of pregnant women were analyzed. Adverse outcomes mainly include preterm birth, fetal growth restriction, fetal distress, postpartum hemorrhage, neonatal asphyxia, neonatal death, premature rupture of membranes, placental abruption, as shown in Table 2. It can be seen that the level of serum M-CSF in patients with adverse pregnancy outcomes in the first trimester (11–13+6 weeks) was significantly higher than that in patients with NP outcomes (Fig. 4a). We used the ROC method to analyze the predictive value of the serum M-CSF level in the first trimester (11–13+6 weeks) for the pregnancy outcome of HDCP patients. The cutoff value (528.88 pg/mL), sensitivity (82.76%), and specificity (52.69%) were determined by the maximum value of Youden's index (Fig. 4b).

The study mainly investigated the role of serum M-CSF as a potential biomarker for HDCP. M-CSF1 is a cytokine protein primarily produced by various cell types within the body, including mesenchymal cells, endothelial cells, and stromal cells [13]. However, the main cellular source of M-CSF1 is monocytes and macrophages. M-CSF1 plays a pivotal role in regulating the differentiation, proliferation, survival, and function of monocytes, macrophages, and their precursor cells [14]. It binds to its receptor, CSF-1R, which is expressed on the surface of target cells [14]. Upon binding, M-CSF1 triggers signaling cascades within the cells, leading to the activation of various downstream pathways involved in cell growth, differentiation, and survival [15]. Through its actions on monocytes and macrophages, M-CSF1 influences immune responses, tissue repair, inflammation, and other physiological processes [16]. Additionally, M-CSF1 is implicated in the regulation of bone metabolism and development, as well as reproductive processes, including fertility and pregnancy [17‒19]. It also initiates and enhances the killing effect of macrophages on tumor cells and microorganisms, regulates the release of cytokines and other inflammatory regulators from macrophages, and stimulates pinocytosis [5, 20]. Dysregulation of M-CSF1 signaling has been associated with various pathological conditions, including inflammatory disorders, cancer, and bone disease. Usually, the amount of M-CSF secreted by cells will increase when the embryo implants [6, 21]. On the contrary, the amount of M-CSF secreted by cells is relatively small in women who fail to implant or have repeated miscarriages [22]. Regarding M-CSF levels in nonpregnant individuals with a history of hypertension or in hypertensive individuals, research suggests that M-CSF levels may be dysregulated [23]. Hypertension is often associated with chronic low-grade inflammation and endothelial dysfunction, both of which can affect the production and regulation of M-CSF [24]. Research indicates that M-CSF levels in high-risk groups during pregnancy can vary significantly compared to normal pregnancies [11]. High-risk groups, such as those with conditions like preeclampsia or gestational diabetes, may exhibit altered M-CSF levels. In some studies, it has been observed that M-CSF levels may be elevated in high-risk pregnancies, particularly in cases of preeclampsia, which is characterized by hypertension and organ dysfunction [11]. Elevated M-CSF levels have been associated with increased inflammation and immune system dysregulation, which are common features of preeclampsia [11, 25]. Furthermore, dysregulated angiogenesis due to elevated M-CSF levels may lead to vascular abnormalities, impacting tissue perfusion and organ development in the embryo [26].

Our analysis first demonstrated the predictive value of serum M-CSF in early pregnancy for HDCP, as well as the predictive value of serum M-CSF in early pregnancy for pregnancy outcomes in HDCP patients. We demonstrated significantly higher levels of serum M-CSF in the HDCP group compared to the NP group during the first trimester. This suggests that M-CSF may be associated with the pathogenesis of HDCP and could potentially serve as a diagnostic marker. The ROC analysis revealed reasonable sensitivity and specificity of serum M-CSF levels in predicting HDCP. Furthermore, a correlation analysis demonstrated a positive association between serum M-CSF levels and 24-h proteinuria, as well as SBP at the time of diagnosis in HDCP patients during the first trimester. This supports the hypothesis that M-CSF may be involved in the inflammatory and hypertensive processes associated with HDCP. Additionally, the study explored the relationship between serum M-CSF levels and inflammatory factors, such as TNF-α and IL-6, in different HDCP subgroups. The analysis revealed a significant positive correlation between serum M-CSF levels and inflammatory factors, further supporting the involvement of M-CSF in the inflammatory response observed in HDCP.

M-CSF plays a significant role in inflammation as it is involved in the regulation and activation of immune cells, particularly macrophages [27]. Macrophages are crucial components of the innate immune system and are responsible for engulfing and eliminating pathogens, as well as regulating the immune response [28]. The study assessed the relationship between serum M-CSF levels during the first trimester and pregnancy outcomes in HDCP patients. The observed higher levels of serum M-CSF in HDCP patients compared to those with normal pregnancies suggest that M-CSF may be implicated in the pathophysiology of HDCP. The positive correlation between serum M-CSF levels and inflammatory factors, such as TNF-α and IL-6, further supports the involvement of M-CSF in the inflammatory response observed in HDCP. It is possible that M-CSF contributes to the activation of immune cells and the release of pro-inflammatory cytokines, leading to endothelial dysfunction, impaired placental development, and subsequent hypertensive disorders during pregnancy.

The findings of the study highlight the potential utility of serum M-CSF as a diagnostic and predictive biomarker for HDCP. The ROC analysis demonstrated reasonable sensitivity and specificity of serum M-CSF levels in identifying patients with HDCP during the first trimester. This suggests that serum M-CSF could be a valuable tool in the early detection and risk assessment of HDCP. Early identification of women at high risk for HDCP would enable timely interventions and close monitoring to mitigate adverse pregnancy outcomes. Early detection, close monitoring of blood pressure and proteinuria, regular fetal surveillance, and timely delivery planning are crucial to optimizing maternal and neonatal outcomes. The study's results underscore the importance of appropriate management and monitoring of pregnant women with HDCP. The classification of HDCP into GH, mPE, and sPE highlights the varying degrees of disease severity and associated risks. The high incidence of poor pregnancy outcomes, including prematurity, fetal growth restriction, fetal distress, and placental complications, emphasizes the need for comprehensive care and specialized management protocols for women with HDCP.

It is important to acknowledge certain limitations of the study. The sample size was relatively small, which may limit the generalizability of the findings. Additionally, the study focused on the first trimester and did not explore the potential changes in serum levels of M-CSF throughout the course of pregnancy. Further studies with larger cohorts and longitudinal assessments of serum M-CSF levels are warranted to validate the findings and establish the clinical utility of M-CSF as a biomarker for HDCP.

This study provides valuable insights into the clinical characteristics, classification, and pregnancy outcomes of women with HDCP. It highlights the significance of proteinuria, elevated blood pressure, and adverse pregnancy outcomes associated with HDCP. Furthermore, it suggests a potential role of serum M-CSF as a diagnostic and predictive biomarker for HDCP, with higher levels correlating with disease severity, inflammation, and adverse pregnancy outcomes. These findings contribute to our understanding of HDCP and may have implications for improving risk assessment, early detection, and management strategies for this hypertensive disorder during pregnancy.

The study was approved by the Ethics Committee of Changchun University of Chinese Medicine Affiliated Hospital, and written informed consent was obtained from the participants. The study was performed in strict accordance with the Declaration of Helsinki, Ethical Principles for Medical Research Involving Human Subjects.

The authors declare that they have no conflicts of interest.

This study was not supported by any sponsor or funder.

Conception and design of the study: Lili Zhou, Junbo Liu, Min Zhou, and Lan Xu. Data acquisition, analysis, and interpretation and manuscript drafting: Lili Zhou, Junbo Liu, and Min Zhou. All authors critically revised the manuscript and approved the final version.

The data used to support the findings of this study are available from the corresponding author upon request.