MMP-9、TNF-α、IL-1在无菌性松动界膜组织中的表达及相关性研究

目的通过观察人工关节无菌性松动假体周围界膜组织和骨性关节炎滑膜组织中MMP-9、TNF-α、IL-1表达情况,探索三者与无菌性松动发生的关系及相关性。方法选取2017年1月至2018年12月宁夏医科大学总医院收治的膝关节置换术后假体无菌性松动患者行翻修术时切取的假体周围界膜组织作为无菌性松动组(20例),膝关节骨性关节炎患者行初次膝关节置换术时切取的滑膜组织作为骨性关节炎组(30例)。通过常规HE染色观察其组织学形态,免疫组化法检测MMP-9、TNF-α、IL-1的表达情况,通过Image-Pro Plus检测三者的平均积分光密度。结果假体周围界膜组织似致密的结缔组织,结构混乱、层次不清。界膜组织被大量磨损颗粒填充并可见大量炎症细胞浸润其中,尤以巨噬细胞多见。骨性关节炎滑膜组织呈慢性炎症的表现,可见炎性细胞如单核细胞、淋巴细胞等明显浸润以及新生血管的增生,亦可见巨噬细胞的增生、肥大。MMP-9、T-NF-、IL-1在两种组织中均有表达,差异无统计学意义(>0.05);在无菌性松动组中TNF-α和MMP-9的表达差异有统计学意义且成正相关性(=0.916,<0.01),IL-1和MMP-9的表达差异有统计学意义且成正相关性(=0.606,<0.01)。在骨关节炎组中TNF-α和MMP-9的表达差异有统计学意义且成正相关性(=0.830,<0.01),IL-1和MMP-9的表达差异有统计学意义且成正相关性(=0.734,<0.01)。结论 MMP-9、TNF-α、IL-1在无菌性松动界膜组织和骨关节炎滑膜组织中均增加,磨损颗粒促进了无菌性松动界膜组织的炎性反应,可以通过抑制MMP-9、TNF-α、IL-1的表达和相互作用以及减少磨损颗粒的产生来缓解无菌性松动的进展。     

Expression of urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor-1 and -2 in hepatocellular carcinoma

It has become more and more clear in recent decades that the plasminogen activation system, which includes urokinase-type plasminogen activator (uPA), urokinase-type plasminogen activator receptor (uPAR), plasminogen activator inhibitor (PAI)-1 and PAI-2, plays a very important role in the aggressiveness of cancer. Using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), the expression of these four components of the uPA system was analyzed in 19 cases of hepatocellular carcinoma (HCC) and 18 cases of the adjacent non-cancer tissues which all had chronic active hepatitis with liver fibrosis or liver cirrhosis. Four cases of normal liver tissues, as controls for immunohistochemical stains, were obtained from the hepatectomized liver of patients with metastatic cancer in the liver. The positive rates of uPA, uPAR, PAI-1 and PAI-2 for immunohistochemical stains in cancer tissues were 78.9, 68.4, 57.9 and 31.6%, respectively. Positive signals were mainly distributed in the cytoplasm of the cancer and in stromal cells. Moreover, the strong stains were chiefly located in the invasive front of the cancer cells. No specific stain was detected in four cases of normal liver tissues. In ELISA, there were significant differences between cancer and non-cancer tissues in concentration of uPA, uPAR and PAI-1 (P < 0.0003, 0.0024 and 0.01, respectively), but there was no significant difference in that of PAI-2 (P = 0.37). These results suggest that uPA, uPAR and PAI-1 are related to invasion of HCC.     

The urokinase-type plasminogen activator and inhibitors in resectable lung adenocarcinoma

BackgroundThe urokinase-type plasminogen activator (uPA) system is closely related to the occurrence and progression of cancer in many aspects. Previous studies demonstrated that the conclusions about the prognosis value of uPA, plasminogen activator inhibitor 1 (PAI-1) and plasminogen activator inhibitor 2 (PAI-2) in lung cancer are controversial, so this study was performed for the exploration of the predictive effect of uPA, PAI-1 and PAI-2 on the overall survival (OS) of resectable pulmonary adenocarcinoma patients.MethodsUPA, PAI-1 and PAI-2 expression levels were assayed by immunohistochemical staining based on tissue microarray (TMA) that is composed of formalin-fixed paraffin-embedded specimens from 84 resectable lung adenocarcinoma patients from July 2004 to June 2009. The relationship of IHC, mRNA expression levels of three molecules were investigated respectively. The three molecules’ relationship with clinicopathologic parameters and OS was explored by Chi-square, Kaplan-Meier, and Cox regression analyses. The Cancer Genome Atlas (TCGA) database was used to analyze differential gene expressions of RNA-sequencing data of pulmonary adenocarcinoma and normal tissues, and Kaplan-Meier methods were adopted to confirm the prognostic value of uPA, PAI-1 and PAI-2 in resectable lung adenocarcinoma in TCGA database and the R package MethylMix was used to conduct an analysis integrating methylation data and gene expression of RNA-sequencing data based on TCGA.ResultsUPA, PAI-1 and PAI-2 had much higher IHC expression levels in tumor than those in the normal tissues (uPA, Z = -10.511; PAI-1, Z = -4.836; PAI-2, Z = -6.794; all P < 0.0001). High DNA methylation level of gene uPA resulted in the decrease of its expression. In addition, expression level of PAI-2 was positively associated with tumor size (χ² = 8.372, P = 0.004). Multivariate analyses showed TNM stage III was an independent adverse prognostic factor (hazard ratio = 3.736, 95 % confidence interval = 1.097–12.72, P = 0.035). Kaplan-Meier method revealed that uPA, PAI-1 and PAI-2 expression levels were not related to the OS for 84 resectable lung adenocarcinoma patients. According to TCGA data, PAI-1 expression level was identified as a potential adverse predictor for prognosis of resectable lung adenocarcinoma (Gehan-Breslow-Wilcoxon test, P = 0.025).ConclusionsOur data show that, the expression levels of uPA, PAI-1 and PAI-2 are significantly up-regulated in resectable lung adenocarcinoma. Besides, this study highlights PAI-1 as a latent adverse prognostic factor in resectable adenocarcinoma of lung.     

Expression of urokinase-type plasminogen activator,its receptor,and its inhibitor in gastric adenocarcinoma tissues.

The plasminogen and plasmin system, which is mainly regulated by urokinase-type plasminogen activator (uPA), its receptor (uPAR) and its inhibitor (PAI-1), is generally believed to play a role in cancer invasion and metastasis. This study was conducted to investigate the role of uPA, uPAR and PAI-1 in the invasion and metastasis of gastric adenocarcinoma. The expression of mRNAs for uPA and PAI-1 was determined by Northern blot analysis in nine primary gastric cancer tissues, nine paired metastatic lymph nodes and normal gastric mucosa. The mRNA of uPA was not or faintly detected in normal mucosa, while the expression was increased in both primary gastric cancer tissues and metastatic lymph nodes to a similar degree. The mRNA expression for PAI-1 in the gastric cancer tissues was not different from that in the paired metastatic lymph nodes and normal mucosae. uPAR was determined by immunohistochemical staining, demonstrating that five (56%) and six (67%) out of nine primary gastric cancer tissues and nine paired metastatic lymph nodes were positive, respectively and the intensity was stronger in metastatic lymph nodes. The results support the concept that most gastric cancer cells may have an innately moderate level of uPA and uPAR, and that increase of uPAR expression can be considered to be closely associated with cancer invasion and metastasis.     

Kinetics of matrix metalloproteinases and their regulatory factorsin mercuric chloride-induced tubulointerstitial fibrosisin Brown Norway rats

We investigated the kinetics of matrix metalloproteinases (MMPs) and their regulatory factors mRNAs in the kidneys of mercuric chloride-treated Brown Norway rats. The expression of MMP-1 mRNA remained at lower levels than control, while other MMPs mRNAs were upregulated. The expression of tissue inhibitor of matrix metalloproteinase (TIMP)-1 mRNA showed significant upregulation. On the other hand, the expressions of TIMP-2 and TIMP-3 mRNAs were not significantly changed. In the plasmin-dependent pathway, the expression of plasminogen activator inhibitor (PAI-1) mRNA was continuously increased, while the expression of urokinase-type plasminogen activator (uPA) mRNA was not increased. The signals of TIMP-1 and PAI-1 mRNAs examined by in situ hybridization, were localized in the regenerative epithelial cells of the proximal tubules. In conclusion, these findings suggest that the activity of MMPs may bealtered by MMP-1 downregulation and inhibition of MMP activity by PAl-1 and TIMP-1 generated from tubular epithelial cells.     

Immunohistochemical expression of uPA, uPAR, and PAI-1 in breast carcinoma. Fibroblastic expression has strong associations with tumor pathology

The urokinase-type plasminogen activator (uPA) system has been implicated in tumor spread. We have used immunohistochemistry to examine three components of this system, ie, uPA, uPA receptor (uPAR), and plasminogen activator inhibitor-1 (PAI-1), in a pilot study on 142 cases of breast carcinoma. We wished to determine whether there were any relationships between expression of the proteins in either tumor cells or fibroblasts and clinical and pathological features. Strong uPA expression in each cell type was significantly related to high tumor grade (P = 0.013 and 0.008, respectively), and was more common in invasive than in in situ carcinomas (P < 0.0001). Fibroblastic expression of uPAR was only related to the presence of invasion (P < 0.0001). Strong PAI-1 expression in both cell types was seen in high-grade tumors (tumor cells, P = 0.012; fibroblasts, P < 0.001), but only fibroblastic expression was related to the presence of invasion (P = 0.042). Fibroblastic expression of both uPA and uPAR were positively correlated with tumor size. Although patients with strong fibroblastic expression of uPA showed a tendency toward a shorter time to relapse, none of the plasminogen activator proteins were significantly associated with relapse-free survival. These results suggest that strong expression of uPA, uPAR, and PAI-1 in fibroblasts rather than in tumor cells have the most impact on the clinical behavior of breast cancer. Larger prospective studies are needed to confirm these findings.     

Signalling networks associated with urokinase-type plasminogen activator (uPA) and its inhibitor PAI-1 in breast cancer tissues: new insights from protein microarray analysis

The urokinase-type plasminogen activator (uPA) and the main uPA inhibitor PAI-1 play important roles in cell migration and invasion in both physiological and pathological contexts. Both factors are clinically applicable predictive markers in node-negative breast cancer patients that are used to stratify patients for adjuvant chemotherapy. In addition to their classical functions in plasmin regulation, both factors are key components in cancer-related cell signalling. Such signalling cascades are well described in cell culture systems, but a better understanding of uPA- and PAI-1-associated signalling networks in clinical tissues is needed. We examined the expression of uPA, PAI-1, and 21 signalling molecules in 201 primary breast cancer tissues using protein microarrays. Expression of uPA was significantly correlated with the expression of ERK and Stat3, while expression of PAI-1 was correlated with the uPA receptor and Akt activation, presumably via integrin and HER-receptor signalling. Analysis of uPA expression did not reveal any significant correlation with staging, grading or age of the patients. The PAI-1 expression was correlated with nodal stage. Network monitoring for uPA and PAI-1 in breast cancer reveals interactions with main signalling cascades and extends the findings from cell culture experiments. Our results reveal possible mechanisms underlying cancer development.     

Markers of the uPA system and common prognostic factors in breast cancer

The urokinase plasminogen activator (uPA) system includes uPA and plasminogen activator inhibitor types 1 (PAI-1) and 2 that mainly act by regulating extracellular matrix degradation, and it is involved in tumor progression. The -675 4G/5G polymorphism of the PAI-1 gene regulates PAI-1 activity in serum. We aimed at studying the -675 4G/5G polymorphism of the PAI-1 gene and uPA, PAI-1, and cyclooxygenase-2 (COX-2) immunohistochemical expression in a series of breast cancer cases. Homozygosity for the 4G allele of the PAI-1 gene was associated with node-positive breast cancer ( P = .02). We showed a direct correlation between uPA and estrogen receptor expression ( P = .03); negative uPA expression was associated with negative hormonal expression, high tumor grade, and high proliferation index ( P < .05). A direct correlation was seen between uPA and PAI-1, uPA and COX-2, and PAI-1 and COX-2 expression ( P < .05). Interaction between uPA and COX-2 systems in breast cancer deserves further study.     

Prognostic relevance of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitors PAI-1 and PAI-2 in gastric cancer

Expression of urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2) was evaluated in 125 surgically resected gastric cancers by immunohistochemical analysis. Tissue was stained immunohistochemically with a monoclonal antibody against human uPA and monoclonal antibodies against human PAI-1 and PAI-2. In addition, DNA ploidy patterns were determined by cytofluorometer after staining with propidium iodide. We found that 82 (66%) of the 125 gastric cancers expressed uPA as diffuse cytoplasmic staining, as intensely outlined luminal borders. PAI-1 expression was observed in 62 (50%) of 125 gastric cancer as a fine, diffuse and granular pattern in the cytoplasm. PAI-2 expression was observed in 65 (52%) of the 125 gastric cancers as a diffuse cytoplasmic staining. uPA-positive tumours showed a higher incidence of infiltration, lymph node metastasis and peritoneal dissemination than uPA-negative ones. Patients with uPA-positive tumours proved to have a significantly poorer prognosis than those with negative ones. PAI-1-negative tumours showed a higher incidence of liver metastasis and carried a poorer prognosis than PAI-1-positive ones. There was no significant correlation between uPA or PAI-1 expression and DNA ploidy patterns. Conversely, there was no significant relationship between PAI-2 expression and clinicopathological parameters and prognosis. According to the expression of uPA and PAI-1 status, groups of 19 uPA(–)/PAI-1(–), 44 uPA(+)/PAI-1(–), 23 uPA(–)/PAI-1(+) and 39 uPA(+)/PAI-1(+) were subdivided. Tumours with UPA(+)/PAI-1(–) had a significantly higher incidence of liver metastasis, lymph node metastasis and serosal invasion than the other groups of tumours. Patients with uPA(+)/PAI-1(–) tumours had a significantly poorer prognosis than those with uPA(–)/PAI-1(+) tumours. These results indicate that uPA expression is a useful biological prognostic indicator, and that uPA and PAI-1 may play an important part in the tumour progression and metastasis in gastric cancer.     

Cyclooxygenase-2 expression correlates with uPAR levels and is responsible for poor prognosis of colorectal cancer

Considering recent findings that cyclooxygensase-2 (COX-2) is involved in the progression of colorectal carcinoma (CRC), the role of COX-2 in promoting invasion and angiogenesis was investigated by evaluating the relationship of COX-2 expression to various clinicopathological variables, including plasminogen activating system (PA system) and vascular endothelial growth factor (VEGF). Tumor tissues from 71 patients with CRC were assayed to determine the antigen levels of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), and plasminogen activator inhibitor-1 and -2 (PAI-1 and PAI-2), as well as immunohistochemical expression of VEGF. COX-2 was assayed immunohistochemically in 56 patients. COX-2 expression was detected in cancer cells and it was also expressed by stromal cells in some patients. Fourteen patients (25%) were COX-2 positive, whereas 42 were negative. COX-2 expression was significantly related to lymphatic invasion (P=0.0317), but was not related to microvessel density or VEGF expression. In the PA system, uPAR antigen levels were significantly higher in tumors with COX-2 expression than in tumors without (P=0.0233). Univariate analysis showed that significant prognostic variables for survival were tumor size, lymph node involvement, lymphatic invasion, vascular invasion, liver metastasis, high uPAR level, and COX-2 expression, but only liver metastasis was an independent prognostic factor (P=0.0065) in multivariate analysis. COX-2 expression was a more important prognostic indicator than any other factor except liver metastasis (P=0.0526). The significant relationship between the presence of COX-2 protein and uPAR antigen levels contributed to the enhancement of tumor invasion and the poor outcome in patients with CRC. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dysregulation of matrix metalloproteinases and their tissue inhibitors is related to abnormality of left ventricular geometry and function in streptozotocin-induced diabetic minipigs

This study aimed to characterize matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in relation to changes in left ventricle (LV) geometry and function in a porcine model with streptozotocin (STZ)-induced diabetes. In 15 Chinese Guizhou minipigs with STZ-induced diabetes (diabetic group) and 15 age-matched normal controls (control group), Doppler tissue imaging was performed at 6 months of diabetes. Serum MMP-2, -9, TIMP-1, -4 and B-type natriuretic peptide (BNP) were determined. Expression of MMPs, TIMPs, urokinase type-plasminogen activator (uPA), its receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1) in aortic intima and LV myocardium was evaluated, with gelatinolytic activities of tissue MMP-2, -9 accessed by zymography. Left ventricle end-diastolic septum thickness (P < 0.05) and mass (P < 0.05) were increased, whereas peak systolic mitral annulus velocity (Sm, P < 0.001), LV systolic (P = 0.01) and diastolic strain (P < 0.001) were significantly decreased in diabetic group than in controls. Diabetic group showed higher expression of TIMP-1, -4 in aortic intima and LV myocardium (P < 0.01 or P < 0.05), with increased collagen content and elevated serum BNP level (P = 0.004) and lower gelatinolytic activities of tissue MMP-2, -9 (all P < 0.05). Semi-quantitative RT-PCR of those diabetic tissues revealed elevated mRNA levels of major TIMPs, uPA, uPAR and PAI-1. Reduction of serum MMP-2 and -9 levels was observed in diabetic group vs. control group (both P < 0.05). This study features elevated levels of TIMP-1, -4, uPA, uPAR and PAI-1, and decreased activities of MMP-2, -9 in aorta and myocardium in STZ-induced diabetic minipigs, indicating that MMP-TIMP dysregulation is associated with LV hypertrophy, cardiac dysfunction and increased cardiovascular fibrosis in diabetes.     

Expression of matrix metalloproteinases-1, -2, and -9; tissue inhibitors of matrix metalloproteinases-1 and -2; cathepsin B; urokinase plasminogen activator; and plasminogen activator inhibitor, type I in skull base chordoma

Little is known about proteinase expression in skull base chordoma, a rare bone tumor exhibiting local invasiveness. Using immunohistochemical techniques, we investigated the expression of matrix metalloproteinases (MMPs)-1, -2, and -9; tissue inhibitors of matrix metalloproteinases (TIMPs)-1 and -2; cathepsin B (CatB); urokinase plasminogen activator (uPA); and plasminogen activator inhibitor, type I (PAI1), in 45 patients with skull base chordoma (45 primary and 25 autologous recurrent lesions). We compared these data with clinicopathologic parameters and the expression of cell differentiation markers. MMP-1, MMP-2, TIMP-1, CatB, uPA, and PAI1 were frequently expressed, and there was a significant correlation in the expression of some proteinases. Immunoreactivity for MMP-1, MMP-2, CatB, and uPA was significantly higher in lesions exhibiting tumor infiltration of host bone than in those without such components. Expression of MMP-1, TIMP-1, CatB, and uPA was associated with that of low-molecular-weight cytokeratin (CAM5.2). There were no differences in proteinase expression in 25 pairs of primary and their recurrent lesions, and proteinase expression did not predict local recurrences. However, patients with higher expression of both MMP-1 and uPA showed worse prognosis compared with the others. In conclusion, expression of some proteinases correlated with CAM5.2 expression and seemed to play an important role in a synergistic manner in the invasion process in skull base chordoma. The authors believe that elevated expression of MMP-1 and uPA can be used to identify patients with a worse prognosis in skull base chordoma.     

Induction of the plasminogen activator system by mechanical stimulation of human bronchial epithelial cells

Mechanical stimulation of the airway epithelium, as would occur during bronchoconstriction, is a potent stimulus and can activate profibrotic pathways. We used DNA microarray technology to examine gene expression in compressed normal human bronchial epithelial cells (NHBE). Compressive stress applied continuously over an 8-h period to NHBE cells led to the upregulation of several families of genes, including a family of plasminogen-related genes that were previously not known to be regulated in this system. Real-time PCR demonstrated a peak increase in gene expression of 8.0-fold for urokinase plasminogen activator (uPA), 16.2-fold for urokinase plasminogen activator receptor (uPAR), 4.2-fold for plasminogen activator inhibitor-1 (PAI-1), and 3.9-fold for tissue plasminogen activator (tPA). Compressive stress also increased uPA protein levels in the cell lysates (112.0 versus 82.0 ng/ml, P = 0.0004), and increased uPA (4.7 versus 3.3 ng/ml, P = 0.02), uPAR (1.3 versus 0.86 ng/ml, P = 0.007), and PAI-1 (50 versus 36 ng/ml, P = 0.006) protein levels in cell culture media. Functional studies demonstrated increased urokinase-dependent plasmin generation in compression-stimulated cells (0.0090 versus 0.0033 OD/min, P = 0.03). In addition, compression led to increased activation of matrix metalloproteinase (MMP)-9 and MMP-2 in a urokinase-dependent manner. In postmortem human lung tissue, we observed an increase in epithelial uPA and uPAR immunostaining in the airways of two patients who died in status asthmaticus compared with minimal immunoreactivity noted in airways from seven lung donors without asthma. Together these observations suggest an integrated response of airway epithelial cells to mechanical stimulation, acting through the plasminogen-activating system to modify the airway microenvironment.     

检测DM2患者血浆tPA、PAI-1、uPA及uPAR水平的价值

目的:检测2型糖尿病(DM2)血浆tPA、PAI-1、uPA及uPAR水平,探讨其临床价值.方法:分别以ELISA检测尿蛋白正常组、尿蛋白阳性组、严重尿蛋白组和对照组的tPA、PAI-1、uPA及uPAR水平.结果:与对照组相比,尿蛋白正常组的tPA和PAI-1变化不明显(P＞0.05);尿蛋白阳性组tPA活性明显下降...     

Urokinase-type plasminogen activator and plasminogen activator inhibitor type-1 mRNA assessment in breast cancer by means of NASBA: correlation with protein expression

Urokinase plasminogen activator (uPA) and its main inhibitor, plasminogen activator inhibitor type-1 (PAI-1) determined in tumor tissue by means of enzyme-linked immunosorbent assay (ELISA) can discriminate patients with primary breast cancer at high risk vs low risk for recurrence. The aim of this study was to analyze uPA and PAI-1 messenger RNA (mRNA) expression by means of quantitative nucleic acid sequence-based amplification (NASBA) on 77 primary breast tumor samples and to correlate this expression with the uPA and PAI-1 protein content. We observed that the 2 markers were significantly overexpressed (uPA, P < .0001; PAI-1, P = .0042) in mRNA in the ELISA+ group. The receiver operating characteristic (ROC) curves demonstrated high concordance between NASBA and ELISA (area under the ROC curve of 0.84 and 0.70 for uPA and PAI-1, respectively) and showed that uPA and PAI-1 status could be predicted by using the molecular assay with sensitivity and specificity values of 80.8% and 82.4% and sensitivity and specificity values of 66.7% and 74.0%, respectively.     

Vascular endothelial growth factor, epidermal growth factor and fibroblast growth factor-4 and -10 stimulate trophoblast plasminogen activator system and metalloproteinase-9

Trophoblast invasion, accompanied by degradation of extracellular matrix, is crucial to normal pregnancy development, whereas shallow placental invasion and implantation likely plays a role in the subsequent development of pre-eclampsia. The growth factors vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and fibroblast growth factor (FGF) are placental growth factors that activate degradation of extracellular matrix. We determined the effect of VEGF, EGF, FGF-2, FGF-4 and FGF-10 on the plasminogen activator system of first trimester cytotrophoblasts cultured in vitro. We studied the activity of urokinase plasminogen activator (uPA), its inhibitor plasminogen activator inhibitor-1 (PAI-1), and 92 kDa gelatinase-B (matrix metalloproteinase-9, MMP-9), using protein gel and reversed gel zymography. The expression pattern of FGF-4 and FGF-10 in human placental sections was determined by immunohistochemistry. FGF-4 was expressed in first trimester villi stroma, primarily in endothelial cells. FGF-10 expression was localized to first trimester extravillous trophoblasts. VEGF, EGF, FGF-4 and FGF-10, but not FGF-2, stimulate the activity of trophoblast uPA, PAI-1 and MMP-9. These results support the hypothesis that specific growth factors modulate the invasive potential of trophoblasts, and therefore may play an important role in early placental development. Our findings may contribute to the understanding of the pathophysiology of diseases associated with shallow placentation, such as pre-eclampsia.