An Alternative Approach to Determining Metabolic Syndrome Component Cutoffs in Children and Adolescents Using Segmental Regression Analysis.

Background: The prevalence of metabolic syndrome is increasing in children and adolescents. Although some diagnostic criteria for metabolic syndrome exist, further research is needed to determine appropriate age-, sex-, and race-specific cutoffs for each component. Methods and Results: Health examinations were conducted in 1,679 children aged 6-15 years in 9 regions of Japan. Participants were divided into 3 age groups for each sex: 6-8, 9-11, and 12-15 years. For metabolic syndrome components in each group, inverse cumulative percentile graphs were drawn and approximated by 3 regression lines using segmented regression analysis. The intersection of each regression line was defined as the breakpoint, and the measured value corresponding to the breakpoint percentile as the breakpoint value. Breakpoint values for waist circumference were age dependent at approximately 60, 70, and 80 cm for ages 6-8, 9-11, and 12-15 years, respectively. Breakpoint values for blood pressure were age- and/or sex dependent, while those for triglycerides, high-density lipoprotein cholesterol, and fasting blood glucose were neither age nor sex dependent. Based on these results, we proposed new cutoffs for diagnosing metabolic syndrome in Japanese children and adolescents. Conclusions: Breakpoint values obtained by segmented regression analysis on inverse cumulative percentile graphs can be useful for determining metabolic syndrome component cutoffs in children and adolescents.

Prenatal risk factors of indoor environment and incidence of childhood eczema in the Japan Environment and Children's Study.

The quality of indoor environment is a risk factor for early childhood eczema and atopic dermatitis; however, its influence during pregnancy on childhood eczema in Japan has not been investigated. In this study, we aimed to determine the indoor environmental factors that are associated with eczema in children up to 3 years of age, using national birth cohort data from the Japan Environment and Children's Study (JECS). Information on indoor environments and eczema symptoms until 3 years of age was collected using self-administered questionnaires to the mothers. A total of 71,883 and 58,639 mother-child pairs at 1.5- and 3-years-old, respectively, were included in the former analyses. To account for prenatal indoor risk factors, 17,568 (1.5-years-old) and 7063 (3-years-old) children without indoor mold and/or ETS exposure were included in the final analysis. A higher mold index, gas heater use, parquet flooring use, and frequent insecticide use showed significantly increased risks for childhood eczema up to 3 years of age. These associations were consistent after stratification analysis among children whose parents did not have a history of allergies. The updated WHO guidelines on indoor air quality should be implemented based on recent findings regarding the effects of prenatal exposure to indoor dampness on health effects of children further in life, including asthma, respiratory effects, eczema, and other immunological effects.

Prostanoids Regulate Angiogenesis and Lymphangiogenesis in Pathological Conditions.

Angiogenesis, the formation of new blood vessels from the preexistent microvasculature, is an essential component of wound repair and tumor growth. Nonsteroidal anti-inflammatory drugs that suppress prostanoid biosynthesis are known to suppress the incidence and progression of malignancies including colorectal cancers, and also to delay the wound healing. However, the precise mechanisms are not fully elucidated. Accumulated results obtained from prostanoid receptor knockout mice indicate that a prostaglandin E-type receptor signaling EP3 in the host microenvironment is critical in tumor angiogenesis inducing vascular endothelial growth factor A (VEGF-A). Further, lymphangiogenesis was also enhanced by EP signaling via VEGF-C/D inductions in pathological settings. These indicate the importance of EP receptor to facilitate angiogenesis and lymphangiogenesis in vivo. Prostanoids act beyond their commonly understood activities in smooth muscle contraction and vasoactivity, both of which are quick responses elicited within several seconds on stimulations. Prostanoid receptor signaling will be a potential therapeutic target for disease conditions related to angiogenesis and lymphangiogenesis.

Mortality in childhood-onset type 1 diabetes mellitus with onset between 1959 and 1996: A population-based study in Hokkaido, Japan.

Aim: To examine the mortality rate and causes of death in childhood-onset type 1 diabetes in Japan. Methods: For a median 36.7 years, we followed 391 patients under the age of 15 years who developed type 1 diabetes between 1959 and 1996. We calculated the mortality rate per 100,000 person-years and the standardised mortality ratio (SMR) according to risk factors. Results: The mortality rates and SMRs were 823 and 8.8 with onset during 1959-1979, 370 and 5.9 with onset during 1980-1989, and 133 and 3.2 with onset during 1990-1996, respectively. The mortality rates and SMRs were 359 and 8.4 in men, and 235 and 6.0 in women. Mortality rates and SMRs were 452 and 7.3 in patients with diabetes onset before puberty and 514 and 6.3 in patients with onset after puberty. The main causes of death with shorter disease duration were sudden death, accident/suicide, and acute diabetic complications. With a more than 30-year disease duration, the main causes of death were end-stage renal disease and cardiovascular disease. Conclusions: This cohort study revealed a decrease in the mortality rate between 1959-1979 and 1990-1996 in patients with childhood-onset type 1 diabetes in Japan. Patients with onset after puberty had a higher mortality rate than those with onset before puberty.

The association between prenatal per-and polyfluoroalkyl substance levels and Kawasaki disease among children of up to 4 years of age: A prospective birth cohort of the Japan Environment and Children's study.

Kawasaki disease (KD) is common among pediatric patients and is associated with an increased risk of later cardiovascular complications, though the precise pathophysiology of KD remains unknown. Per- and polyfluoroalkyl substances (PFAS) have gathered notoriety as the causal pathogens of numerous diseases as well as for their immunosuppressive effects. The present epidemiological study aims to assess whether PFAS may affect KD risk. We evaluated research participants included in the ongoing prospective nationwide birth cohort of the Japan Environment and Children's Study (JECS). Among the over 100,000 pregnant women enrolled in the JECS study, 28 types of PFAS were measured in pregnancy in a subset of participants (N = 25,040). The JECS followed their children born between 2011 and 2014 (n total infants = 25,256; n Kawasaki disease infants = 271), up to age four. Among the 28 types of PFAS, those which were detected in >60 % of participants at levels above the method reporting limit (MRL) were eligible for analyses. Multivariable logistic regressions were implemented on the seven eligible PFAS, adjusting for multiple comparison effects. Finally, we conducted Weighted Quantile Sum (WQS) and Bayesian kernel machine regression (BKMR) to assess the effects of the PFAS mixture on KD. Therefore, we ran the BKMR model using kernel mechanical regression equations to examine PFAS exposure and the outcomes of KD. Upon analysis, the adjusted multivariable regression results did not reach statistical significance for the seven eligible substances on KD, while odds ratios were all under 1.0. WQS regression was used to estimate the mixture effect of the seven eligible PFAS, revealing a negative correlation with KD incidence; similarly, BKMR implied an inverse association between the PFAS mixture effect and KD incidence. In conclusion, PFAS exposure was not associated with increased KD incidence.

Deletion of RAMP1 Signaling Enhances Diet-induced Obesity and Fat Absorption via Intestinal Lacteals in Mice.

BACKGROUND/AIM: Intestinal lymphatic vessels (lacteals) play a critical role in the absorption and transport of dietary lipids into the circulation. Calcitonin gene-related peptide and receptor activity-modifying protein 1 (RAMP1) are involved in lymphatic vessel growth. This study aimed to examine the role of RAMP1 signaling in lacteal morphology and function in response to a high-fat diet (HFD). MATERIALS AND METHODS: RAMP1 deficient (RAMP1-/-) or wild-type (WT) mice were fed a normal diet (ND) or HFD for 8 weeks. RESULTS: RAMP1-/- mice fed a HFD had increased body weights compared to WT mice fed a HFD, which was associated with high levels of total cholesterol, triglycerides, and glucose. HFD-fed RAMP1-/- mice had shorter and wider lacteals than HFD-fed WT mice. HFD-fed RAMP1-/- mice had lower levels of lymphatic endothelial cell gene markers including vascular endothelial growth factor receptor 3 (VEGFR3) and lymphatic vascular growth factor VEGF-C than HFD-fed WT mice. The concentration of an absorbed lipid tracer in HFD-fed RAMP1-/- mice was higher than that in HFD-fed WT mice. The zipper-like continuous junctions were predominant in HFD-fed WT mice, while the button-like discontinuous junctions were predominant in HFD-fed RAMP1-/- mice. CONCLUSION: Deletion of RAMP1 signaling suppressed lacteal growth and VEGF-C/VEGFR3 expression but accelerated the uptake and transport of dietary fats through discontinuous junctions of lacteals, leading to excessive obesity. Specific activation of RAMP1 signaling may represent a target for the therapeutic management of diet-induced obesity.

Prenatal metal concentrations and physical abnormalities in the Japan Environment and Children's Study.

BACKGROUND: The association between prenatal metal exposure and congenital anomalies is unclear. We aimed to examine the association between exposure to cadmium, lead, mercury, selenium, and manganese and physical abnormalities. METHODS: Data from 89,887 pregnant women with singleton pregnancies who participated in the Japan Environment and Children's Study (JECS) were used. The correlation between maternal blood metal concentrations and physical abnormalities during the second or third trimester was investigated using logistic regression models. Physical anomalies included those observed at birth or at 1 month, primarily from ICD-10 Chapter 17, particularly congenital anomalies associated with environmental factors (e.g., hypospadias, cryptorchidism, cleft lip and palate, digestive tract atresia, congenital heart disease, and chromosomal abnormalities) and minor abnormalities. RESULTS: After adjusting for covariates, the OR (95% CIs) of physical abnormalities for a one-unit rise in Mn concentrations in all individuals were 1.26 (1.08, 1.48). The OR (95% CIs) of physical abnormalities in the 4th quartile (≥18.7 ng/g) were 1.06 (1.01, 1.13) (p-value for the trend = 0.034) compared with those in the 1st quartile (≤12.5 ng/g). CONCLUSION: In Japan, maternal blood Mn concentrations above threshold during pregnancy may slightly increase the incidence of physical abnormalities. IMPACT: Physical abnormalities (including minor anomalies and congenital anomalies) are associated with prenatal manganese concentrations. They are not associated with cadmium, lead, mercury, and selenium concentrations.

Inhibition of TP signaling promotes endometriosis growth and neovascularization.

Endometriosis is highly dependent on angiogenesis and lymphangiogenesis. Prostaglandin E2, an arachidonic acid metabolite, has been shown to promote the formation of new blood and lymphatic vessels. However, the role of another arachidonic acid metabolite, thromboxane A2 (TXA2) in angiogenesis and lymphangiogenesis during endometriosis remains largely unexplored. Using a murine model of ectopic endometrial transplantation, fragments from the endometrium of WT donor mice were transplanted into the peritoneal walls of recipient WT mice (WT→WT), resulting in an increase in both the area and density of blood and lymphatic vessels. Upon transplantation of endometrial tissue from thromboxane prostanoid (TP) receptor (TXA2 receptor)­deficient (TP­/­) mice into TP­/­ mice (TP­/­â†’TP­/­), an increase in implant growth, angiogenesis, and lymphangiogenesis were observed along with upregulation of pro­angiogenic and lymphangiogenic factors, including vascular endothelial growth factors (VEGFs). Similar results were obtained using a thromboxane synthase (TXS) inhibitor in WT→WT mice. Furthermore, TP­/­â†’TP­/­ mice had a higher number of F4/80+ cells than that of WT→WT mice, with increased expression of genes related to the anti­inflammatory macrophage phenotype in endometrial lesions. In cultured bone marrow (BM)­derived macrophages, the levels of VEGF­A, VEGF­C, and VEGF­D decreased in a TP­dependent manner. Furthermore, TP signaling affected the polarization of cultured BM­derived macrophages to the anti­inflammatory phenotype. These findings imply that inhibition of TP signaling promotes endometrial implant growth and neovascularization.

Thromboxane prostanoid signaling in macrophages attenuates lymphedema and facilitates lymphangiogenesis in mice : TP signaling and lymphangiogenesis.

BACKGROUND: Accumulating evidence suggests that prostaglandin E2, an arachidonic acid (AA) metabolite, enhances lymphangiogenesis in response to inflammation. However, thromboxane A2 (TXA2), another AA metabolite, is not well known. Thus, this study aimed to determine the role of thromboxane prostanoid (TP) signaling in lymphangiogenesis in secondary lymphedema. METHODS AND RESULTS: Lymphedema was induced by the ablation of lymphatic vessels in mouse tails. Compared with wild-type mice, tail lymphedema in Tp-deficient mice was enhanced, which was associated with suppressed lymphangiogenesis as indicated by decreased lymphatic vessel area and pro-lymphangiogenesis-stimulating factors. Numerous macrophages were found in the tail tissues of Tp-deficient mice. Furthermore, the deletion of TP in macrophages increased tail edema and decreased lymphangiogenesis and pro-lymphangiogenic cytokines, which was accompanied by increased numbers of macrophages and gene expression related to a pro-inflammatory macrophage phenotype in tail tissues. In vivo microscopic studies revealed fluorescent dye leakage in the lymphatic vessels in the wounded tissues. CONCLUSIONS: The results suggest that TP signaling in macrophages promotes lymphangiogenesis and prevents tail lymphedema. TP signaling may be a therapeutic target for improving lymphedema-related symptoms by enhancing lymphangiogenesis.

A biologically active lipid, thromboxane, as a regulator of angiogenesis and lymphangiogenesis.

Thromboxane (TX) and prostaglandins are metabolites of arachidonic acid, a twenty-carbon unsaturated fatty acid, and have a variety of actions that are exerted via specific receptors. Angiogenesis is defined as the formation of new blood vessels from pre-existing vascular beds and is a critical component of pathological conditions, including inflammation and cancer. Lymphatic vessels play crucial roles in the regulation of interstitial fluid, immune surveillance, and the absorption of dietary fat from the intestine; and they are also involved in the pathogenesis of various diseases. Similar to angiogenesis, lymphangiogenesis, the formation of new lymphatic vessels, is a critical component of pathological conditions. The TP-dependent accumulation of platelets in microvessels has been reported to enhance angiogenesis under pathological conditions. Although the roles of some growth factors and cytokines in angiogenesis and lymphangiogenesis have been well characterized, accumulating evidence suggests that TX induces the production of proangiogenic and prolymphangiogenic factors through the activation of adenylate cyclase, and upregulates angiogenesis and lymphangiogenesis under disease conditions. In this review, we discuss the role of TX as a regulator of angiogenesis and lymphangiogenesis, and its emerging importance as a therapeutic target.

Comparison of physician- and self-assessed pubertal onset in Japanese children.

Introduction: Physical examinations to assess pubertal development are challenging in large epidemiological surveys. This study aimed to assess the reliability of judgment of pubertal onset in Japanese children by the original pubertal self-assessment sheet. Methods: A total of 144 children aged 10 or 12 years were recruited between March 2019 and September 2020 from the pediatric endocrine outpatient clinics of participating institutions. Agreement between the physician- and participantassessed pubertal onsets was determined using unweighted kappa (UK) and Gwet's agreement coefficient (AC1). Results: The physician's assessment of pubertal onset was in slight agreement with that of the self-assessment sheet in 10-year-old boys (UK: 0.23 and AC1: 0.14), whereas the agreement between the physician's assessment and self-assessment sheet results was good and the physician's assessment was fair (UK: 0.64 and AC1: 0.94) in 12-year-old boys. The physician's assessment of pubertal onset were in good and moderate agreement with the self-assessment sheet in 10-year-old girls (UK/AC1: 0.74/0.78, respectively). In 12-year-old girls, although it showed poor agreement with UK (0.46), there was a very good agreement with AC1 (0.88). Conclusions: Although self-assessment of breast development was in good agreement with that of the physician's assessment for determining pubertal onset in girls, large-scale epidemiological studies are difficult to conduct for adolescent boys, especially for those in the early pubertal stage.

Responses of hepatic sinusoidal cells to liver ischemia-reperfusion injury.

The liver displays a remarkable regenerative capacity in response to acute liver injury. In addition to the proliferation of hepatocytes during liver regeneration, non-parenchymal cells, including liver macrophages, liver sinusoidal endothelial cells (LSECs), and hepatic stellate cells (HSCs) play critical roles in liver repair and regeneration. Liver ischemia-reperfusion injury (IRI) is a major cause of increased liver damage during liver resection, transplantation, and trauma. Impaired liver repair increases postoperative morbidity and mortality of patients who underwent liver surgery. Successful liver repair and regeneration after liver IRI requires coordinated interplay and synergic actions between hepatic resident cells and recruited cell components. However, the underlying mechanisms of liver repair after liver IRI are not well understood. Recent technological advances have revealed the heterogeneity of each liver cell component in the steady state and diseased livers. In this review, we describe the progress in the biology of liver non-parenchymal cells obtained from novel technological advances. We address the functional role of each cell component in response to liver IRI and the interactions between diverse immune repertoires and non-hematopoietic cell populations during the course of liver repair after liver IRI. We also discuss how these findings can help in the design of novel therapeutic approaches. Growing insights into the cellular interactions during liver IRI would enhance the pathology of liver IRI understanding comprehensively and further develop the strategies for improvement of liver repair.

Association between maternal multimorbidity and preterm birth, low birth weight and small for gestational age: a prospective birth cohort study from the Japan Environment and Children's Study.

OBJECTIVES: Multimorbidity is defined as the coexistence of two or more chronic physical or psychological conditions within an individual. The association between maternal multimorbidity and adverse perinatal outcomes such as preterm delivery and low birth weight has not been well studied. Therefore, this study aimed to investigate this association. METHODS: We conducted a prospective cohort study using data from the Japan Environment and Children's Study of pregnant women between 2011 and 2014. Those with data on chronic maternal conditions were included in the study and categorised as having no chronic condition, one chronic condition or multimorbidities. The primary outcomes were the incidence of preterm birth (PTB), low birth weight (LBW) and small for gestational age (SGA). Adjusted logistic regression was performed to estimate ORs (aORs) and 95% CIs. RESULTS: Of the 104 062 fetal records, 86 885 singleton pregnant women were analysed. The median maternal age and body mass index were 31 years and 20.5 kg/m2, respectively. The prevalence of pregnant women with one or more chronic conditions was 40.2%. The prevalence of maternal multimorbidity was 6.3%, and that of PTB, LBW, and SGA were 4.6%, 8.1%, and 7.5%, respectively. Pre-pregnancy underweight women were the most common, observed in 15.6% of multimorbidity cases, followed by domestic violence from intimate partner in 13.0%. Maternal multimorbidity was significantly associated with PTB (aOR 1.50; 95% CI 1.33-1.69), LBW (aOR 1.49; 95% CI 1.35-1.63) and SGA (aOR 1.33; 95% CI 1.20-1.46). CONCLUSION: Maternal multimorbidity was associated with adverse perinatal outcomes, including PTB, LBW and SGA. The risk of adverse perinatal outcomes tends to increase with a rise in the number of chronic maternal conditions. Multimorbidity becomes more prevalent among pregnant women, making our findings important for preconception counselling.

Developmental trajectories at a high risk for childhood overweight/obesity.

BACKGROUND: The associations between developmental patterns (trajectories) in children and maternal factors have been widely investigated, but paternal effects on these trajectories are unclear. This study aimed to determine child and parental factors involved in developmental trajectories at high risk for causing adverse cardiovascular (CV) profiles in children. METHODS: We analyzed longitudinal anthropometric data from birth to the present and CV profiles of 1,832 healthy volunteers (51% girls) aged 3-15 years who participated in a nationwide study between July 2012 and January 2014. Six trajectory latent class growth models were developed using body mass index z- scores. Predictors for being in developmental trajectories at high risk for causing adverse CV profiles were determined by multivariate regression analysis. RESULTS: The mean±standard deviation number of anthropometric data points was 12±3 for both boys and girls. Among the six trajectories, the infantile onset and continual increase groups had significantly worse levels of many CV profiles than those in the remaining groups. Paternal overweight/obesity was an independent predictor for boys being in the infantile onset group and for girls being in the continual increase group. Additionally, maternal pre-pregnancy overweight/obesity in boys and maternal excessive gestational weight gain in girls were independent predictors for being in the infantile onset group. Having no sibling in boys and an older maternal age were independent predictors for being in the continual increase group. CONCLUSIONS: Interventions to prevent childhood obesity should include strategies that focus on fathers and mothers as well as those that focus on children with certain types of familial background.

Variability and Seasonal Change of Urinary Selenium, Molybdenum, and Iodine Excretion in Healthy Young Japanese Adults.

Selenium (Se), molybdenum (Mo), and iodine (I) are essential trace elements or nutrients and their adequate intake is essential for human health. These elements in foods are easily absorbed from the digestive tract and excreted predominantly into the urine, and their nutritional status is reflected in urinary excretion; however, information on the variability of urinary excretion is limited. To characterize the urinary Se, Mo, and I concentrations and their intra- and inter-individual coefficients of variation (CV), correlation, and seasonal change, spot urine samples were collected from 24 healthy university students, 10 males and 14 females, with the mean age of 20.6 years, for 10 consecutive days in each of the four seasons according to a defined schedule of an interval of 3 months throughout 1 year. The median Se, Mo, and I concentrations for all urine samples (n = 947) were 52.8, 127.0, and 223 µg/L, respectively. The Se and Mo intakes were highest in summer and lowest in spring, while the I intake was highest in autumn and lowest in summer. In all three elements, the intra-individual CVs were smaller than their inter-individual CVs. The log-transformed intra- and inter-individual CVs were 10.5 and 14.7% for Se, 12.3 and 15.1% for Mo, and 15.5 and 18.1% for I. There was no gender difference in Se and I concentrations, while Mo and Mo/Cr values in males were higher than those in females. Our results suggest adequate nutritional status of Se, Mo, and I with a relatively smaller variability of dietary intake except for I in this population.

Associated congenital anomalies and syndromes of 248 infants with orofacial clefts born between 2011 and 2014 in the Japan environment and children's study.

This study aimed to document the complication status of infants with orofacial clefts born between 2011 and 2014 in Japan. This was a descriptive study using data from the Japan Environment and Children's Study. Among 103 060 pregnancies, 248 infants with orofacial clefts were included (livebirth, 239; stillbirth, 4; miscarriage, 5). The items of interest were complication status of orofacial clefts: isolated (typical orofacial clefts only); multi-malformed (orofacial clefts with unrelated major defects); syndromic (orofacial clefts with a syndrome or a chromosomal defect). Regarding the cleft subtypes, of 248 infants with orofacial clefts, 104 had cleft lip with cleft palate (CLP) (41.9%), 68 had cleft lip without cleft palate (CL) (27.4%), 58 had cleft palate without cleft lip (CP) (23.4%), and 18 were nonclassified (7.3%). In infants with CLP, the proportions of isolated, multi-malformed, and syndromic phenotypes were 73.1%, 15.4%, and 11.5%, respectively. In infants with CL, the proportions were 79.4%, 16.2%, and 4.4%, respectively. In infants with CP, the proportions were 69.0%, 13.8%, and 17.2%, respectively. The most frequently associated congenital anomaly was congenital heart disease. In infants with syndromic CLP, 41.7% had trisomy 13. In infants with syndromic CP, 80.0% had the Pierre Robin sequence. Congenital heart disease could be the most frequently associated congenital anomaly. The most frequently associated syndrome could be trisomy 13 in those with CLP and Pierre Robin sequence in those with CP.

Iodine Metabolism and Thyroid Function During the Perinatal Period: Maternal-Neonatal Correlation and Effects of Topical Povidone-Iodine Skin Disinfectants.

An adequate maternal iodine intake during pregnancy and lactation is essential for growth and mental development in fetuses and newborns. There are limited data on perinatal iodine metabolism in mothers and infants, as well as the effect of povidone-iodine (PVP-I) antiseptics used in cesarean delivery. The urinary iodine concentration (UIC), serum iodine, thyrotropin (TSH), free thyroxine (FT4), and breast milk iodine concentration (BMIC) were measured consecutively in a total of 327 mothers and 249 term-infants in two prospective studies. The maternal median UIC was 164 µg/L in the third trimester, increased to 256 µg/L at 44 h after birth, and then decreased to 116 µg/L 1 month later. The BMIC on the 4th and 32th postpartum days was 17.6 and 13.5 µg/100 g, respectively. In neonatal infants born to the mothers unexposed to PVP-I, the median UIC was 131 µg/L in the first voiding urine and increased to 272 µg/L on day 4 and then slightly decreased to 265 µg/L on day 28 suggesting sufficient iodine reserve at birth. PVP-I antiseptics containing 1 g of iodine for skin preparation at cesarean delivery transiently increased maternal serum iodine concentration (1.9-fold), UIC (7.8-fold) at 41 h after surgery and BMIC, while it had little effect on maternal TSH, FT4, and neonatal UIC, TSH, or FT4. The iodine status of pregnant women and their infants was adequate in this population; however, the UIC in lactating mothers at one postpartum month was low enough to suggest iodine deficiency or near iodine deficiency. Further studies are necessary.

The microsomal prostaglandin E synthase-1/prostaglandin E2 axis induces recovery from ischaemia via recruitment of regulatory T cells.

AIMS: Microsomal prostaglandin E synthase-1 (mPGES-1)/prostaglandin E2 (PGE2) induces angiogenesis through the prostaglandin E2 receptor (EP1-4). Among immune cells, regulatory T cells (Tregs), which inhibit immune responses, have been implicated in angiogenesis, and PGE2 is known to modulate the function and differentiation of Tregs. We hypothesized that mPGES-1/PGE2-EP signalling could contribute to recovery from ischaemic conditions by promoting the accumulation of Tregs. METHODS AND RESULTS: Wild-type (WT), mPGES-1-deficient (mPges-1-/-), and EP4 receptor-deficient (Ep4-/-) male mice, 6-8 weeks old, were used. Hindlimb ischaemia was induced by femoral artery ligation. Recovery from ischaemia was suppressed in mPges-1-/- mice and compared with WT mice. The number of accumulated forkhead box protein P3 (FoxP3)+ cells in ischaemic muscle tissue was decreased in mPges-1-/- mice compared with that in WT mice. Expression levels of transforming growth factor-ß (TGF-ß) and stromal cell derived factor-1 (SDF-1) in ischaemic tissue were also suppressed in mPges-1-/- mice. The number of accumulated FoxP3+ cells and blood flow recovery were suppressed when Tregs were depleted by injecting antibody against folate receptor 4 in WT mice but not in mPges-1-/- mice. Recovery from ischaemia was significantly suppressed in Ep4-/- mice compared with that in WT mice. Furthermore, mRNA levels of Foxp3 and Tgf-ß were suppressed in Ep4-/- mice. Moreover, the number of accumulated FoxP3+ cells in ischaemic tissue was diminished in Ep4-/- mice compared with that in Ep4+/+ mice. CONCLUSION: These findings suggested that mPGES-1/PGE2 induced neovascularization from ischaemia via EP4 by promoting the accumulation of Tregs. Highly selective EP4 agonists could be useful for the treatment of peripheral artery disease.