Cell surface ATP synthase-released H+ and ATP play key roles in cocoa butter intake-mediated regulation of gut immunity through releases of cytokines in rat.

Proper food intake is important for maintaining good health in humans. Chocolate is known to exert anti-inflammatory effects; however, the mechanisms remain unclear. In this study, we aimed to investigate the effects of cocoa butter intake on gut immunity in rats and rabbits. Cocoa butter intake increased the lymph flow, cell density, and IL-1ß, IL-6 and IL-10 levels in mesenteric lymph. Clodronate, a macrophage depletion compound, significantly enhanced the release of all cytokines. The immunoreactivities of macrophage markers CD68 and F4/80 in the jejunal villi were significantly decreased with clodronate. Piceatannol, a selective cell surface ATP synthase inhibitor significantly reduced the cocoa butter intake-mediated releases of IL-1ß, IL-6 and IL-10. The immunoreactivities of cell surface ATP synthase were observed in rat jejunal villi. Shear stress stimulation on the myofibroblast cells isolated from rat jejunum released ATP and carbon dioxide depended with H+ release. In rabbit in vivo experiments, cocoa butter intake increased the concentrations of ATP and H+ in the portal vein. The in vitro experiments with isolated cells of rat jejunal lamina propria the pH of 3.0 and 5.0 in the medium released significantly IL-1ß and IL-6. ATP selectively released IL-10. These findings suggest that cocoa butter intake regulates the gut immunity through the release and transport of IL-1ß, IL-6, and IL-10 into mesenteric lymph vessels in a negative feedback system. In addition, the H+ and ATP released from cell surface ATP synthase in jejunal villi play key roles in the cocoa butter intake-mediated regulation of gut immunity.

Portal blood flow-dependent NO-mediated lymph formation in rat jejunum.

The higher permeability of the venules in jejunal microcirculation to albumin contributes to the increased mesenteric lymph formation. Recently, we demonstrated that water intake induced serotonin release from enterochromaffin cells in rat jejunum, serotonin of which circulated through the portal vein into blood circulation and then increased the mesenteric lymph formation. The mode of action of serotonin remains unclear. Therefore, we aimed to clarify the mechanisms involved in the regulation of the jejunal lymph formation with permeant albumin in in vivo rat experiments. We investigated the effects of intravenous administration of serotonin or water intake on the jejunal-originated lymph volume and the concentration of albumin in the lymph in the presence or absence of L-NAME. The effects of intravenous administration of L-NAME, nicardipine, A23187, and ML-7 on the lymph formation with permeant albumin were also evaluated. Serotonin or water intake significantly increased the mesenteric lymph volume with permeant albumin in the jejunal microcirculation. The serotonin- and water intake-mediated responses were significantly reduced by the pretreatment with intravenous administration of L-NAME. Intravenous administration of L-NAME itself also decreased significantly the jejunal lymph formation. Administration of A23187 and ML-7 significantly reduced the jejunal lymph formation with permeant albumin. In contrast, administration of nicardipine significantly increased the lymph formation. In conclusion, portal venous blood flow- or serotonin-mediated NO release from venular endothelial cells plays physiologically key roles in the lymph formation in rat jejunum via the extrusion of calcium ions and inactivation of MLCK in endothelial cells.

GATA2 participates in the recanalization of lymphatic vessels after surgical lymph node extirpation.

Lymphatic recanalization failure after lymphadenectomy constitutes a major risk of lymphedema in cancer surgery. It has been reported that GATA2, a zinc finger transcription factor, is expressed in lymphatic endothelial cells and is involved in the development of fetal lymphatic vessels. GATA3, another member of the GATA family of transcription factors, is required for the differentiation of lymphoid tissue inducer (LTi) cells and is essential for lymph node formation. However, how GATA2 and GATA3 function in recanalization after the surgical extirpation of lymphatic vessels has not been elucidated. Employing a new model of lymphatic recanalization, we examined the lymphatic reconnection process in Gata2 heterozygous deficient (Gata2+/- ) and Gata3 heterozygous deficient (Gata3+/- ) mice. We found that lymphatic recanalization was significantly impaired in Gata2+/- mice, while Gata3+/- mice rarely showed such abnormalities. Notably, the perturbed lymphatic recanalization in the Gata2+/- mice was partially restored by crossing with the Gata3+/- mice. Our results demonstrate for the first time that GATA2 participates in the regeneration of damaged lymphatic vessels and the unexpected suppressive activity of GATA3 against lymphatic recanalization processes.

Water intake releases serotonin from enterochromaffin cells in rat jejunal villi.

The present study aims to investigate the roles of water intake in serotonin production and release in rat jejunum. We evaluated the changes in concentrations of serotonin in the portal vein and mesenteric lymph vessel induced by the intragastric administration of distilled water. The density of granules in enterochromaffin cells and the immunoreactivity of serotonin in the jejunal villi were investigated before and after water intake. The effects of intravenous administration of serotonin and/or ketanserin on mesenteric lymph flow and concentrations of albumin and IL-22 in the lymph were also addressed. Water intake increased serotonin concentration in the portal vein, but not in the mesenteric lymph vessel. The flux of serotonin through the portal vein was significantly larger than that through the mesenteric lymph vessel. Water intake decreased the density of granules in the enterochromaffin cells and increased the immunoreactivity of serotonin in the jejunal villi. The intravenous administration of serotonin increased significantly mesenteric lymph flow and the concentrations of albumin and IL-22; both were significantly reduced by the intravenous pretreatment with ketanserin. We showed that serotonin released from enterochromaffin cells by water intake was mainly transported through the portal vein. Additionally, serotonin in blood was found to increase mesenteric lymph formation with permeant albumin in the jejunal villi via the activation of 5-HT2 receptor.

Another route of CO2 gas excretion independent of red blood cells in human lungs.

We demonstrated pulmonary arteriolar blood flow-mediated CO2 gas excretion in rabbit lungs. The shear stress stimulation produced CO2 gas in cultured human endothelial cells of pulmonary arterioles via the activation of F1/Fo ATP synthase. To confirm the findings in human subjects undergoing the operation with heart-lung machines, we aimed to evaluate the effects of a stepwise switch, from a partial to a complete cardiopulmonary bypass, of the circulatory blood volume (BV, 100% = 2.4 × cardiac index), on the end-expiratory CO2 pressure (PetCO2), maximal flow velocity in the pulmonary artery (Max Vp), the inner diameter (ID) of pulmonary artery, pulmonary arterial CO2 pressure (P mix v CO2), pulmonary arterial O2 pressure (P mix v O2), hematocrit (Hct), pH, the concentration of HCO3-, and base excess (BE) in mixed venous blood in 9 patients with a mean age of 72.3 ± 3.4 years. In addition, the effects of the decrease in Hct infused with physiological saline solution (PSS) on PetCO2 were investigated in the human subjects. An approximately linear relationship between the PetCO2 and Max Vp was observed. The pumping out of 100% BV produced little or no change in the Hct, pH, P mix v CO2, and P mix v O2, respectively. The hemodilution produced by intravenous infusion of PSS caused a significant decrease in the Hct, but not in the PetCO2. In conclusion, another route of CO2 gas excretion, independent of red blood cells, may be involved in human lungs.

Water intake accelerates ATP release from myofibroblast cells in rats: ATP-mediated podoplanin-dependent control for physiological function and immunity.

We previously demonstrated that water intake increased mesenteric lymph flow and the total flux of IL-22 in rat jejunum. The drained water and the higher permeability of albumin in the jejunal microcirculation contributed to increase the lymph flow and IL-22 transport via the activation of great bulk flow in the jejunal villi. To address the effects of water intake-mediated great bulk flow-dependent mechanical force on jejunal physiological function and immunological regulation of innate lymphoid cells (ILC)-3, we examined the effects of shear stress stimulation on cultured rat myofibroblast cells. Next, we investigated the effects of water intake on podoplanin and IL-22 expressions in cultured human intestinal epithelial cells and rat in vivo jejunal preparations, respectively. Shear stress stimulation of the myofibroblast cells induced ATP release via an activation of cell surface F1/F0 ATP synthase. ATP produced podoplanin expression in the intestinal epithelial cells. Water intake accelerated immunohistochemical expressions of podoplanin and IL-22 in the interepithelial layers and lamina propria of the jejunum. ATP dose-dependently increased IL-22 mRNA expression in ILC-3, which are housed in the lamina propria. Water intake also increased immunohistochemical and mRNA expressions of ecto-nucleoside triphosphate diphosphohydrolases 2 and 5 in jejunal villi. In conclusion, water intake-mediated shear stress stimulation-dependent ATP release from myofibroblast cells maintains higher tissue colloid osmotic pressure in the jejunal microcirculation through podoplanin upregulation in the interepithelial layers. ATP induces IL-22 mRNA expression in ILC-3 in jejunal villi, which may contribute to regulation of mucosal immunity in small intestine.NEW & NOTEWORTHY We investigated effects of shear stress stimulation on cultured myofibroblast cells and water intake on podoplanin and IL-22 expressions in rat jejunal villi. The stimulation induced ATP release from the cells. Water intake accelerated podoplanin and IL-22 expression levels. ATP increased IL-22 mRNA expression in innate lymphoid cells (ILC)-3. Hence, water intake maintains higher osmotic pressure in the jejunal villi through ATP release and podoplanin upregulation. Water intake may regulate the mucosal immunity.

GATA2 functions in adrenal chromaffin cells.

Catecholamine synthesized in the sympathoadrenal system, including sympathetic neurons and adrenal chromaffin cells, is vital for cardiovascular homeostasis. It has been reported that GATA2, a zinc finger transcription factor, is expressed in murine sympathoadrenal progenitor cells. However, a physiological role for GATA2 in adrenal chromaffin cells has not been established. In this study, we demonstrate that GATA2 is specifically expressed in adrenal chromaffin cells. We examined the consequences of Gata2 loss-of-function mutations, exploiting a Gata2 conditional knockout allele crossed to neural crest-specific Wnt1-Cre transgenic mice (Gata2 NC-CKO). The vast majority of Gata2 NC-CKO embryos died by embryonic day 14.5 (e14.5) and exhibited a decrease in catecholamine-producing adrenal chromaffin cells, implying that a potential catecholamine defect might lead to the observed embryonic lethality. When intercrossed pregnant dams were fed with synthetic adrenaline analogs, the lethality of the Gata2 NC-CKO embryos was partially rescued, indicating that placental transfer of the adrenaline analogs complements the lethal catecholamine deficiency in the Gata2 NC-CKO embryos. These results demonstrate that GATA2 participates in the development of neuroendocrine adrenaline biosynthesis, which is essential for fetal survival.

Cardiac Lymphatic Dysfunction Causes Drug-Eluting Stent-Induced Coronary Hyperconstricting Responses in Pigs In Vivo.

Objective- We have previously demonstrated that coronary adventitial inflammation plays important roles in the pathogenesis of coronary vasomotion abnormalities, including drug-eluting stent (DES)-induced coronary hyperconstricting responses. Importantly, the adventitia also harbors lymphatic vessels, which may prevent inflammation by transporting extravasated fluid and inflammatory cells. We thus aimed to examine the roles of coronary adventitial lymphatic vessels in the pathogenesis of DES-induced coronary hyperconstricting responses in a porcine model in vivo. Approach and Results- We performed 2 experimental studies. In protocol 1, 15 pigs were divided into 3 groups with or without DES and with bare metal stent. Nonstented sites 20 mm apart from stent implantation also were examined. In the protocol 2, 12 pigs were divided into 2 groups with or without lymphatic vessels ligation followed by DES implantation at 2 weeks later (n=6 each). We performed coronary angiography 4 weeks after DES implantation, followed by immunohistological analysis. In protocol 1, the number and the caliber of lymphatic vessels were greater at only the DES edges after 4 more weeks. In protocol 2, coronary hyperconstricting responses were further enhanced in the lymphatic vessels ligation group associated with adventitial inflammation, Rho-kinase activation, and less adventitial lymphatic vessels formation. Importantly, there were significant correlations among these inflammation-related changes and enhanced coronary vasoconstricting responses. Conclusions- These results provide evidence that cardiac lymphatic vessel dysfunction plays important roles in the pathogenesis of coronary vasoconstrictive responses in pigs in vivo.

Water intake increases mesenteric lymph flow and the total flux of albumin, long-chain fatty acids, and IL-22 in rats: new concept of absorption in jejunum.

The traditional Japanese health care custom recommends that a suitable volume of water is consumed. However, physiological and immunological mechanisms in support of this practice are unknown. Therefore, we conducted rat and rabbit in vivo experiments to investigate the effects of intragastric administration of distilled water on the jejunal-originated lymph flow and the concentrations and total flux of cells, albumin, long-chain fatty acids, and innate lymphoid cell 3 (ILC-3)-secreted interleukin-22 (IL-22) through mesenteric lymph vessels. The distribution and activity of ILC-3 in rat small intestine by water intake were evaluated using flow cytometry and RT-PCR. The intragastric administration of distilled water caused significant increases in rat mesenteric lymph flow and in the total flux of cells, albumin, long-chain fatty acids, and IL-22 through the lymph vessels. Intravenously injected Evans blue dye was rapidly transported into rabbit mesenteric lymph vessel and cisterna chyli. The distribution of ILC-3 and the expression of IL-22 mRNA were maximal in the lamina propria cells of the rat jejunum. No significant presence of ILC-3 in the lymph was observed in the control and under water intake conditions. In conclusion, the absorbed water in the jejunum is transported through mesenteric lymph vessels. The higher permeability of albumin in the jejunal microcirculation may play key roles in the transport of consumed water and the reservoir and transporter of long-chain fatty acids. Water intake also accelerates the transfer of IL-22 to the mesenteric lymph, which may contribute, in part, to maintaining and promoting the innate immunity in the body. NEW & NOTEWORTHY The higher permeability of albumin-mediated transport of water-soluble substances in mesenteric lymph vessels of the jejunum may have a large impact on the classic concept suggesting that water-soluble small molecules travel to the liver via the portal vein. ILC-3 is mainly housed in the lamina propria of the jejunum, especially its upper part. IL-22 released from the ILC-3 is also transported through mesenteric lymph in collaboration with the albumin-mediated movement of consumed water.

In vivo support for the new concept of pulmonary blood flow-mediated CO2 gas excretion in the lungs.

To further examine the validity of the proposed concept of pulmonary blood flow-dependent CO2 gas excretion in the lungs, we investigated the effects of intramediastinal balloon catheterization-, pulmonary artery catheterization-, or isoprenaline (ISP)-induced changes in pulmonary blood flow on the end-expiratory CO2 gas pressure (PeCO2 ), the maximal velocity of the pulmonary artery (Max Vp), systemic arterial pressure, and heart rate of anesthetized rabbits. We also evaluated the changes in the PeCO2 in clinical models of anemia or pulmonary embolism. An almost linear relationship was detected between the PeCO2 and Max Vp. In an experiment in which small pulmonary arteries were subjected to stenosis, the PeCO2 fell rapidly, and the speed of the reduction was dependent on the degree of stenosis. ISP produced significant increases in the PeCO2 of the anesthetized rabbits. Conversely, treatment with piceatannol or acetazolamide induced significant reductions in the PeCO2 . Treatment with a cell surface F1/FO ATP synthase antibody caused significant reductions in the PeCO2 itself and the ISP-induced increase in the PeCO2 . Neither the PeCO2 nor SAP was significantly influenced by marked anemia [%hematocrit (Ht), 70 ∼ 47%]. On the other hand, in the presence of less severe anemia (%Ht: 100 ∼ 70%) both the PeCO2 and SAP fell significantly when the rabbits' blood viscosity was decreased. The rabbits in which pulmonary embolisms were induced demonstrated significantly reduced PeCO2 values, which was compatible with the lowering of their Max Vp. In conclusion, we reaffirm the validity of the proposed concept of CO2 gas exchange in the lungs.

Perturbed collagen metabolism underlies lymphatic recanalization failure in Gata2 heterozygous deficient mice.

Lymphedema has become a global health issue following the growing number of cancer surgeries. Curative or supportive therapeutics have long been awaited for this refractory condition. Transcription factor GATA2 is crucial in lymphatic development and maintenance, as GATA2 haploinsufficient disease often manifests as lymphedema. We recently demonstrated that Gata2 heterozygous deficient mice displayed delayed lymphatic recanalization upon lymph node resection. However, whether GATA2 contributes to lymphatic regeneration by functioning in the damaged lymph vessels' microenvironment remains explored. In this study, our integrated analysis demonstrated that dermal collagen fibers were more densely accumulated in the Gata2 heterozygous deficient mice. The collagen metabolism-related transcriptome was perturbed, and collagen matrix contractile activity was aberrantly increased in Gata2 heterozygous embryonic fibroblasts. Notably, soluble collagen placement ameliorated delayed lymphatic recanalization, presumably by modulating the stiffness of the extracellular matrix around the resection site of Gata2 heterozygous deficient mice. Our results provide valuable insights into mechanisms underlying GATA2-haploinsufficiency-mediated lymphedema and shed light on potential therapeutic avenues for this intractable disease.

Cell surface F1/FO ATP synthase contributes to interstitial flow-mediated development of the acidic microenvironment in tumor tissues.

To address pivotal roles of cell surface F1/FO ATP synthase in the development of acidic microenvironment in tumor tissues, we investigated effects of shear stress stimulation on the cultured human breast cancer cells, MDA-MB-231 and MDA-MB-157, or human melanoma cells, SK-Mel-1. Shear stress stimulation (0.5-5.0 dyn/cm(2)), the levels of which are similar to those produced by the interstitial flow, induced strength-dependent corelease of ATP and H(+) from the cells, which triggered CO2 gas excretion. In contrast, the same level of shear stress stimulation did not induce significant ATP release and CO2 gas excretion from the control human mammary epithelial cells (HMEC). Marked immunocytochemical and mRNA expression of cell surface F1/FO ATP synthase, vacuolar-ATPase (V-ATPase), carbonic anhydrase type IX, and ectonucleoside triphosphate diphosphohydrolase (ENTPDase) 3 were detected in MDA-MB-231 cells, but little or no expression on the HMEC. Pretreatment with cell surface F1/FO ATP synthase inhibitors, but not cell surface V-ATPase inhibitors, caused a significant reduction of the shear stress stimulation-mediated ATP release and CO2 gas excretion from MDA-MB-231 cells. The ENTPDase activity in the shear stress-loaded MDA-MB-231 cell culture medium supernatant increased significantly in a time-dependent manner. In addition, MDA-MB-231 cells displayed strong staining for purinergic 2Y1 (P2Y1) receptors on their surfaces, and the receptors partially colocalized with ENTPDase 3. These findings suggest that cell surface F1/FO ATP synthase, but not V-ATPase, may play key roles in the development of interstitial flow-mediated acidic microenvironment in tumor tissues through the shear stress stimulation-induced ATP and H(+) corelease and CO2 gas production.

Sphingosine 1-phosphate (S1P) induces S1P2 receptor-dependent tonic contraction in murine iliac lymph vessels.

OBJECTIVE: We studied the effects of S1P on the diameter and spontaneous contraction of murine iliac collecting lymph vessels. METHODS: The isolated lymph vessel was cannulated with two glass micropipettes and then pressurized to 4 cmH(2) O at the intraluminal pressure. The changes in lymph vessel diameter were measured using a custom-made diameter-detection device. Immunohistochemical studies were also performed to confirm S1P receptors on the lymph vessels. RESULTS: S1P (10(-7) M) had no significant effect on the frequency or amplitude of the lymph vessels' spontaneous contractions. In contrast, S1P (10(-8) -10(-6) M) produced a concentration-related reduction in lymph vessel diameter (tonic contraction). Pretreatment with 10(-4) M l-NAME or 10(-5) M aspirin had no significant effect on the S1P-induced tonic contraction of the lymph vessels. To evaluate the intracellular signal transduction pathway responsible for the S1P-induced tonic contractions and their Ca(2+) -dependence, we investigated the effects of JTE013, VPC23019, U-73122, xestospongin C, and nifedipine on the S1P-induced tonic contractions. All of these inhibitors except VPC23019 and nifedipine significantly reduced the S1P-induced tonic contractions. S1P (5x10(-7) M) also induced significant tonic contractions in the lymph vessels that had been superfused with high K(+) Krebs-bicarbonate solution or Ca(2+) -free high K(+) Krebs solution containing 1 mM EGTA. S1P2 receptors were immunohistochemically detected in the lymph vessels. CONCLUSION: These findings suggest that neither endogenous NO nor prostaglandins are involved in the S1P-induced tonic contraction of lymph vessels, which is mainly caused by Ca(2+) release from intracellular Ca(2+) stores through the activation of S1P2 and 1,4,5 IP(3) receptors.

Physiological Roles of Lymph Flow-Mediated Nitric Oxide in Lymphatic System.

It is known that nitric oxide (NO) is a gas and synthesized from l-arginine by the NO synthase (NOS) in vascular endothelial cells. The diffused NO activates the guanosine monophosphate, which initiates a series of intracellular events, leading to physiological response such as vasodilation. There are three different types of NOS, namely endothelial constitutive NOS (ecNOS), neuronal NOS (nNOS), and cytokine-inducible NOS (iNOS). The ecNOS and nNOS are expressed constitutively at low levels and can be activated rapidly by an increase in cytoplasmic calcium ions. In contrast, the iNOS is induced when macrophages are activated by cytokine, resulting in the induction of pathophysiological effects. Lymph flow is known to stimulate the release of NO from lymphatic endothelial cells (LEC) and then produce the relaxation of lymphatic smooth muscle cells. The NO also plays a key role in the control of lymphatic pump activity in vivo. Many studies have shown the NO-mediated findings in various kinds of lymph vessels. However, there is no or little study to demonstrate the effects of lymph flow on the molecular expression of ecNOS mRNA and the protein. In addition, little study is available for clarifying the relationship between NO and sympathetic nerve fibers in the regulation of lymph transport and production. Therefore, in this review, the experimental findings of lymph flow-mediated increases in the ecNOS mRNA and the protein in LEC are demonstrated in detail. In addition, the roles of NO and aminergic nerve fibers in the physiological control system of lymph transport and production are discussed.

Heatstroke risk informing system using wearable perspiration ratemeter on users undergoing physical exercise.

We constructed an informing system to users for the heatstroke risk using a wearable perspiration ratemeter and the users' thirst responses. The sweating ratemeter was constructed with a capacitive humidity sensor in the ventilated capsule. The timing point for informing heatstroke risk was decided to change from positive to negative on the second derivative of sweating curve. In addition, a wearable self-identification and -information system of thirst response was constructed with a smartphone. To evaluate the validity of wearable apparatus, we aimed to conduct human experiments of 16 healthy subjects with the step up and down physical exercises. The blood and urine samples of the subjects were collected before and after the 30-min physical exercise. The concentrations of TP, Alb, and RBC increased slightly with the exercise. In contrast, the concentrations of vasopressin in all subjects remarkably increased with the exercise. In almost subjects, they identified their thirst response until several min after the informing for heatstroke risk. In conclusion, the wearable ratemeter and self-information system of thirst response were suitable for informing system of heatstroke risk. The validity of timing point for informing heatstroke risk was confirmed with changes in the thirst response and concentrations of vasopressin in blood.

Shear stress-mediated F1/FO ATP synthase-dependent CO2 gas excretion from human pulmonary arteriolar endothelial cells.

We studied the physiological role of flow through pulmonary arterioles in CO(2) gas exchange. We established human pulmonary arteriolar endothelial cells (HPAoEC). The cells demonstrated marked immunocytochemical staining of PECAM-1, VEGF R2, ACE-1, and CA type IV on their cell surface. Ten seconds shear stress stimulation caused the co-release of H(+) and ATP via the activation of F(1)/F(O) ATP synthase on the HPAoEC. F(1)/F(O) ATP synthase was immunocytochemically observed on the cell surface of non-permeabilized HPAoEC. In the shear stress-loaded HPAoEC culture media supernatant, ATPase activity increased in a time-dependent manner. The HPAoEC were strongly stained for NTPDase 1, which partially co-localized with purinergic P2Y1. The purinergic P2Y1 receptor agonist UTP (10(-6) M) significantly potentiated the shear stress-induced increase in ATPase activity in the culture medium supernatant. Ten seconds shear stress stimulation also produced stress strength-dependent CO(2) gas excretion from the HPAoEC, which was significantly reduced by the inhibition of F(1)/F(O) ATP synthase or CA IV on the endothelial cell (EC) surface. In conclusion, we have proposed a new concept of CO(2) exchange in the human lung, flow-mediated F(1)/F(O) ATP synthase-dependent H(+) secretion, resulting in the facilitation of a dehydration reaction involving HCO3(-) in plasma and the excretion of CO(2) gas from arteriolar ECs.

Pivotal roles of shear stress in the microenvironmental changes that occur within sentinel lymph nodes.

A sentinel lymph node (SLN) is the first lymph node that receives drainage from a primary tumor. According to their physiological and biomechanical characteristics, we hypothesized that SLN contains lymphatic endothelial cells (LEC) that are constantly loaded with high levels of shear stress, which might contribute to the production of a suitable environment for micrometastasis within them. To test this hypothesis, we investigated the effects of shear stress stimulation on the expression of adhesion molecules on human LEC isolated from the lymph vessels nearest the SLN of breast cancers, and on the release of ATP from human LEC. The study clarified that the shear stress stimulation produced a significant increase of ICAM-1 expression at protein and mRNA levels in human LEC. Next, we examined whether the shear stress-mediated increase of ICAM-1 expression accelerates the attachment of carcinoma cells to human LEC. Finally, in in vivo experiments, we evaluated whether exogenous ATP facilitates the expression of carcinoma cell-ligated adhesion molecules in rat SLN. In conclusion, shear stress stimulation induces ICAM-1 expression on human LEC by activating cell surface F(1) /F(O) ATP synthase, which might contribute to the development of a premetastatic environment within SLN.

Estimation of the Lymph Flow Through Thoracic Duct in Human Subjects Using the Urine Osmolarity: Applicable for Evaluating the Effectiveness of Manual Lymph Drainage.

Currently, there are many methods to evaluate the effectiveness of manual lymph drainage in the treatment of lymphedema, that is, limb volume measurement, bio-electrical impedance measurement, computer tomography, and ultrasound imaging. However, it is difficult for these methods to accurately address the lymph flow generated by manual lymph drainage. Therefore, we aimed at developing a concise and accurate method to measure the lymph flow through the thoracic duct in human subjects, which is applicable for evaluating the effectiveness of manual lymph drainage. In the present mini-review, we demonstrate the developed method in detail and its scientific evidence for the effectiveness obtained with animal and human clinical experiments. In rat in vivo experiments, intragastric administration of distilled water significantly increased mesenteric flow, which was transported via the cisterna chyli and then the thoracic duct. The manual massage on the cisterna chyli in the anesthetized rabbit significantly accelerated the lymph flow through the thoracic duct, resulting in marked hemodilution. Abdominal respiration in the supine position in human subjects produced similar hemodilution, with a marked decrease in the concentration of vasopressin in the blood. On this basis, we developed a new method to accurately measure the lymph flow through the thoracic duct by using changes in the concentration of vasopressin in the blood. In addition, with changes in urine osmolarity depending on the concentration of vasopressin in the blood, we developed a more concise and noninvasive method for evaluating the lymph flow through the thoracic duct in human subjects. These methods may be applicable for evaluating the effectiveness for the manual lymph drainage in the patients with lymphedema.

Real-time imaging of the lymphatic channels and sentinel lymph nodes of the stomach using contrast-enhanced ultrasonography with Sonazoid in a porcine model.

The contrast-enhanced ultrasound (CEUS)-guided method in combination with Sonazoid has not been clinically or experimentally evaluated with regard to its use for identifying sentinel lymph node (SLN) in the stomach. Therefore, we attempted to evaluate the usefulness of the CEUS-guided method with Sonazoid for imaging of the lymphatic channels and SLN of the stomach in a porcine model by comparing it with the conventional Evans blue dye-guided method. Twenty-eight 2 to 3-month-old swine weighing 17-30 kg were used in this experiment. Anesthesia was maintained with 2.0-3.0% isoflurane/O(2) inhalation. Sonazoid was injected into the intra- and sub-mucosal layers of the stomach. The intragastric or transcutaneous CEUS-guided method was used to identify the lymphatic channels and SLN of the stomach. Contrast imaging using the CEUS-guided method with Sonazoid enabled us to produce clear images of the afferent lymph vessel and SLN of the stomach until 2 h after the injection of Sonazoid. In addition, intranodal flow of the microbubble agent could be clearly identified using tissue linear harmonic images of the SLN. The SLN detection rate was not significantly different between the CEUS- and dye-guided methods. However, the Evans blue dye flowed out quickly (≈ 15 min after the injection) through the true SLN into the next LN of stomach. In conclusion, the use of the CEUS-guided method with Sonazoid might be the most useful clinical procedure for producing real-time images of the SLN of the stomach, and the linear harmonic images are also useful for evaluating intranodal structure within the SLN.

Platelet-derived growth factor (PDGF)-BB produces NO-mediated relaxation and PDGF receptor ß-dependent tonic contraction in murine iliac lymph vessels.

We studied the effects of PDGF-BB on changes in the diameters of murine lymph vessels with or without intact endothelium. PDGF-BB induced dilation of the lymph vessels with endothelium. Pretreatment with l-NAME or removal of the endothelium caused a significant attenuation in the PDGF-BB-induced dilation. PDGF-BB also produced dose-related reduction of the diameters of the lymph vessels without endothelium. To evaluate intracellular signal transduction and Ca(2+) -dependence of the PDGF-BB-induced tonic contraction, we investigated the effects of imatinib, GW5074 (an inhibitor of Raf-1 kinase), U-73122 (an inhibitor of phospholipase C), and xestospongin C on the PDGF-BB-induced reduction responses. All of these inhibitors caused a significant attenuation in the PDGF-BB-induced reduction response that was significantly decreased by treatment with Ca(2+) -free Krebs-bicarbonate solution or nifedipine. Higher concentrations of PDGF-BB produced a marked reduction of lymph vessel diameter within both high K(+) Krebs-bicarbonate solution and Ca(2+) -free high K(+) Krebs solution containing 1mM EGTA. These findings suggest that PDGF-BB induced endothelium-dependent NO-mediated relaxation of lymphatic smooth muscles in murine lymph vessels. PDGF receptor ß-mediated tonic contraction of the muscles through increased Ca(2+) influx through the membrane and the release of membrane-bound and intracellular Ca(2+) .