Endothelium-Derived 5-Methoxytryptophan Protects Endothelial Barrier Function by Blocking p38 MAPK Activation.

The endothelial junction is tightly controlled to restrict the passage of blood cells and solutes. Disruption of endothelial barrier function by bacterial endotoxins, cytokines or growth factors results in inflammation and vascular damage leading to vascular diseases. We have identified 5-methoxytryptophan (5-MTP) as an anti-inflammatory factor by metabolomic analysis of conditioned medium of human fibroblasts. Here we postulated that endothelial cells release 5-MTP to protect the barrier function. Conditioned medium of human umbilical vein endothelial cells (HUVECs) prevented endothelial hyperpermeability and VE-cadherin downregulation induced by VEGF, LPS and cytokines. We analyzed the metabolomic profile of HUVEC conditioned medium and detected 5-MTP but not melatonin, serotonin or their catabolites, which was confirmed by enzyme-linked immunosorbent assay. Addition of synthetic pure 5-MTP preserved VE-cadherin and maintained barrier function despite challenge with pro-inflammatory mediators. Tryptophan hydroxylase-1, an enzyme required for 5-MTP biosynthesis, was downregulated in HUVECs by pro-inflammatory mediators and it was accompanied by reduction of 5-MTP. 5-MTP protected VE-cadherin and prevented endothelial hyperpermeability by blocking p38 MAPK activation. A chemical inhibitor of p38 MAPK, SB202190, exhibited a similar protective effect as 5-MTP. To determine whether 5-MTP prevents vascular hyperpermeability in vivo, we evaluated the effect of 5-MTP administration on LPS-induced murine microvascular permeability with Evans blue. 5-MTP significantly prevented Evans blue dye leakage. Our findings indicate that 5-MTP is a new class of endothelium-derived molecules which protects endothelial barrier function by blocking p38 MAPK

Relationship between PI and ‘Deciduitis’ by a mixed model analysis.

<p>Upper and lower panels indicate the marginal mean and SD values of the ponderal index (PI) and relative ratio of the marginal mean of PI. Red and blue dots indicate infants with and without ‘Deciduitis’. Error bars indicate standard deviations. ‘Deciduitis’ was a significant predictor of a small composition during the first 18 months of life by mixed model analysis (p = 0.035).</p

Representative pathological findings by HE staining in placentas.

<p>(A) ‘Accelerated villous maturation’; the yellow arrow indicates increases in the numbers of placental villi with the focal formation of tight adherent villous clusters with syncytial knots. (B) ‘Decidual vasculopathy’; the yellow arrow indicates the thrombus in decidual vessels. (C) ‘Thrombosis or Intramural fibrin deposition’; the yellow arrow indicates the fibrin cushion in the walls of stem villous vessels. (D) ‘Avascular villi’: the yellow arrow indicates a villi with hyalinized stroma which is devoid of vessels. (E) ‘Delayed villous maturation’; the yellow arrow indicates increases in the size of distal villi, increases in the numbers of stromal cells, and interstitial fluid uniformly distributed throughout the villous stroma. (F) ‘Maternal inflammatory response’; the yellow arrow indicates the infiltration of neutrophils in to the chorionic plate. (G) ‘Fetal inflammatory response’; the yellow arrow indicates the infiltration of neutrophils in to the umbilical vessel. (H) ‘VUE’; the yellow arrow indicates lymphohistiocytic inflammation predominantly in the stroma of terminal villi. (I) ‘Deciduitis’; the yellow arrow indicates the infiltration of lymphocytes and macrophages.</p

Relationship between body weight and ‘Maternal vascular malperfusion’ by a mixed model analysis.

<p>Upper and lower panels indicate the marginal mean and SD values of body weights and the relative ratio of the marginal mean of body weights. Red and blue dots indicate infants with and without ‘Maternal vascular malperfusion’, respectively. Error bars indicate standard deviations. ‘Maternal vascular malperfusion’ was a significant predictor of a light body weight in the first 18 months of life by mixed model analysis (p = 0.020).</p

Perinatal backgrounds of subjects (1).

<p>Perinatal backgrounds of subjects (1).</p

Mixed model analysis of infantile PI during the first 18 months of life.

<p>Mixed model analysis of infantile PI during the first 18 months of life.</p

Relationship between body weight and ‘Accelerated villous maturation’ by a mixed model analysis.

<p>Upper and panels indicate the marginal mean and SD values of body weights and the relative ratio of the marginal mean of body weights. Red and blue dots indicate infants with and without ‘Accelerated villous maturation’, respectively. Error bars indicate standard deviations. ‘Accelerated villous maturation’ was a significant predictor of a light body weight in the first 18 months of life by mixed model analysis (p<0.001).</p

Placental measurement of the subjects in 258 placentas investigated.

<p>Placental measurement of the subjects in 258 placentas investigated.</p

Mixed model analysis of infantile body weight during the first 18 months of life.

<p>Mixed model analysis of infantile body weight during the first 18 months of life.</p

Perinatal backgrounds of subjects (2).

<p>Perinatal backgrounds of subjects (2).</p