Effect of serotonin transporter genotype on self-reported efficacy and activity changes of brain prefrontal area in response to placebo.

Patients benefit from drug therapy not only through pharmacological mechanisms, but also through non-pharmacological action (placebo effect), which may be mediated in part by the prefrontal area of the brain. We consider that the difference between responders and non-responders to placebo might be related to polymorphisms in the serotonin transporter-linked polymorphic region (5-HTTLPR). To study this idea, we performed a randomized double-blind clinical trial using caffeine and lactose (placebo). Activity in the prefrontal area of the brain was measured in terms of blood flow by means of near-infrared spectroscopy (NIRS) as an objective indicator. Self-reported feelings of drowsiness on established scales were used as subjective indicators. Twenty-one subjects in block A took caffeine on the first day and placebo on the third day, and 21 in block B took placebo on the first day and placebo on the third day. After placebo administration, improvement of sleepiness was significantly enhanced, a similar extent to that after caffeine medication. Among the 42 subjects, 22 showed S/S type polymorphism in the serotonin transporter (52.4 %), 17 showed S/L type (40.5 %) and 3 showed L/L type (7.10 %). Statistical analysis of the results indicate that subjects with L/L genotype showed a significantly greater placebo response in terms of both self-reported feeling of drowsiness and blood flow in the prefrontal area of the brain associated with working memory (46 area). Our results indicate that the L/L genotype of 5-HTTLPR, which is rare in Japanese (3.2 %) but common in Americans (32.2 %), may be associated with a greater placebo effect.

High incidence and early onset of nivolumab-induced pneumonitis: four case reports and literature review.

BACKGROUND: Nivolumab, an anti-programmed cell death-1 (PD-1) monoclonal antibody used as an immune checkpoint inhibitor, is commonly employed for its anti-tumor effects against various types of malignant tumors. However, its administration is complicated by immune-related adverse events (irAEs), including pneumonitis. CASE PRESENTATION: We present a case series of four patients with malignant melanoma, non-small cell lung cancer, and hypopharyngeal carcinoma who demonstrated pneumonitis induced by nivolumab, and further review clinicopathological characteristics of these patients in comparison with those of previously reported patients with nivolumab-induced pneumonitis. In our series, 20% of patients who were treated with nivolumab developed pneumonitis, all of which occurred approximately 2 weeks after the initiation of nivolumab treatment. Prompt recognition of the nivolumab-induced pneumonitis allowed for successful resolution. Computed tomography scan images of the patients demonstrated predominantly cryptogenic organizing pneumonia patterns. All patients were males, who had been heavily treated with antitumor drugs prior to nivolumab. CONCLUSIONS: Our case series showed that nivolumab had a high incidence of drug-induced pneumonitis with early onset, supporting the need for renewed attention to nivolumab-induced pneumonitis, particularly in patients with a history of heavy antitumor treatments.

Protective effect of hypotaurine against oxidative stress-induced cytotoxicity in rat placental trophoblasts.

INTRODUCTION: Hypotaurine is a precursor of taurine and an antioxidant, and is concentrated in fetal plasma compared to maternal plasma. Hypotaurine is significantly decreased in fetal plasma of ezrin (Vil2) knock-out mice, and fetuses show intrauterine growth retardation. The aim of this study was to characterize the mechanism through which cellular hypotaurine level is maintained in placental trophoblasts, and the effect of hypotaurine on oxidative stress induced by hydrogen peroxide (H2O2). METHODS: Hypotaurine transfer from extracellular fluid and antioxidant effect of hypotaurine were analyzed in rat placental trophoblast TR-TBT 18d-1 cells. RESULTS: We found that hypotaurine is concentrated into rat placental trophoblast TR-TBT 18d-1 cells, and the level of hypotaurine was markedly reduced by culture in medium supplemented with dialyzed fetal bovine serum (FBS) instead of normal FBS. The hypotaurine level recovered almost completely when hypotaurine was added to the culture medium, indicating that intracellular hypotaurine is predominantly supplied by transport across the plasma membrane from extracellular fluid rather than by biosynthesis. Hypotaurine showed a cytoprotective effect against H2O2-induced oxidative damage in TR-TBT 18d-1 cells. Hypotaurine treatment of TR-TBT 18d-1 cells increased antioxidant capacity against hydroxyl radical and peroxyl radical. The concentration of intracellular hydroxyl radical induced by H2O2 in TR-TBT 18d-1 cells was significantly reduced by hypotaurine treatment. DISCUSSION: These results indicate that intracellular hypotaurine is mainly supplied to placental trophoblasts by transfer from extracellular fluid across the plasma membrane, and may play a role in cell protection by scavenging reactive oxygen species.

Role of protein kinase A in regulating steroid sulfate uptake for estrogen production in human placental choriocarcinoma cells.

The purpose of this study is to assess the role of the protein kinase A (PKA) in regulating uptake of dehydroepiandrosterone sulfate (DHEAS), an estrogen precursor, by syncytiotrophoblasts. Forskolin, a PKA activator, significantly increased [(3)H]DHEAS uptake and the mRNA expression levels of organic anion transporter (OAT) 4 and CYP19A1 in choriocarcinoma JEG-3 cells, while other steroid sulfate transporters present in the placenta showed no change in expression level. KT5720, a PKA inhibitor, attenuated these effects of forskolin. Accordingly, the PKA pathway appears to play an important role in estrogen synthesis by cooperatively regulating OAT4 and steroidogenic enzymes in syncytiotrophoblasts.

Lipid infiltration in the parotid glands: a clinical manifestation of metabolic syndrome.

BACKGROUND: The clinical features of lipid infiltration in the parotid glands (LIPG) have not been studied. Monitoring of atomic-bomb survivors for late effects of radiation exposure has provided the opportunity to review the clinical findings of LIPG. METHODS: A total of 992 atomic-bomb survivors in Nagasaki, Japan underwent lachrymal and salivary secretion tests and anthropometric, biochemical, and abdominal ultrasonographic examinations between 2002 and 2004. Among 465 subjects who had reduced tear and/or salivary excretion, 176 subjects took a salivary magnetic resonance imaging (MRI) examination. RESULTS: LIPG was detected in 53 of the 176 subjects who had salivary MRI. LIPG cases showed a preponderance of females and fatty liver compared with the subjects without LIPG. Age-and-sex-adjusted regression analysis revealed that body mass index (BMI), low-density lipoprotein cholesterol, triglycerides, hemoglobin A1c, and C-reactive protein were higher, whereas high-density lipoprotein cholesterol and adiponectin were lower, in the subjects with LIPG. Multivariate logistic regression analysis showed that BMI and fatty liver were mutually associated with LIPG independently from radiation dose. CONCLUSIONS: LIPG associated with BMI, fatty liver, and coronary risk factors was a clinical manifestation of metabolic syndrome.

Association of genetic variation in FTO with risk of obesity and type 2 diabetes with data from 96,551 East and South Asians.

AIMS/HYPOTHESIS: FTO harbours the strongest known obesity-susceptibility locus in Europeans. While there is growing evidence for a role for FTO in obesity risk in Asians, its association with type 2 diabetes, independently of BMI, remains inconsistent. To test whether there is an association of the FTO locus with obesity and type 2 diabetes, we conducted a meta-analysis of 32 populations including 96,551 East and South Asians. METHODS: All studies published on the association between FTO-rs9939609 (or proxy [r (2) > 0.98]) and BMI, obesity or type 2 diabetes in East or South Asians were invited. Each study group analysed their data according to a standardised analysis plan. Association with type 2 diabetes was also adjusted for BMI. Random-effects meta-analyses were performed to pool all effect sizes. RESULTS: The FTO-rs9939609 minor allele increased risk of obesity by 1.25-fold/allele (p = 9.0 × 10(-19)), overweight by 1.13-fold/allele (p = 1.0 × 10(-11)) and type 2 diabetes by 1.15-fold/allele (p = 5.5 × 10(-8)). The association with type 2 diabetes was attenuated after adjustment for BMI (OR 1.10-fold/allele, p = 6.6 × 10(-5)). The FTO-rs9939609 minor allele increased BMI by 0.26 kg/m(2) per allele (p = 2.8 × 10(-17)), WHR by 0.003/allele (p = 1.2 × 10(-6)), and body fat percentage by 0.31%/allele (p = 0.0005). Associations were similar using dominant models. While the minor allele is less common in East Asians (12-20%) than South Asians (30-33%), the effect of FTO variation on obesity-related traits and type 2 diabetes was similar in the two populations. CONCLUSIONS/INTERPRETATION: FTO is associated with increased risk of obesity and type 2 diabetes, with effect sizes similar in East and South Asians and similar to those observed in Europeans. Furthermore, FTO is also associated with type 2 diabetes independently of BMI.

Association of genetic variants for susceptibility to obesity with type 2 diabetes in Japanese individuals.

AIMS/HYPOTHESIS: In populations of East Asian descent, we performed a replication study of loci previously identified in populations of European descent as being associated with obesity measures such as BMI and type 2 diabetes. METHODS: We genotyped 14 single nucleotide polymorphisms (SNPs) from 13 candidate loci that had previously been identified by genome-wide association meta-analyses for obesity measures in Europeans. Genotyping was done in 18,264 participants from two general Japanese populations. For SNPs showing an obesity association in Japanese individuals, we further examined diabetes associations in up to 6,781 cases and 7,307 controls from a subset of the original, as well as from additional populations. RESULTS: Significant obesity associations (p < 0.1 two-tailed, concordant direction with previous reports) were replicated for 11 SNPs from the following ten loci in Japanese participants: SEC16B, TMEM18, GNPDA2, BDNF, MTCH2, BCDIN3D-FAIM2, SH2B1-ATP2A1, FTO, MC4R and KCTD15. The strongest effect was observed at TMEM18 rs4854344 (p = 7.1 × 10(-7) for BMI). Among the 11 SNPs showing significant obesity association, six were also associated with diabetes (OR 1.05-1.17; p = 0.04-2.4 × 10(-7)) after adjustment for BMI in the Japanese. When meta-analysed with data from the previous reports, the BMI-adjusted diabetes association was found to be highly significant for the FTO locus in East Asians (OR 1.13; 95% CI 1.09-1.18; p = 7.8 × 10(-10)) with substantial inter-ethnic heterogeneity (p = 0.003). CONCLUSIONS/INTERPRETATION: We confirmed that ten candidate loci are associated with obesity measures in the general Japanese populations. Six (of ten) loci exert diabetogenic effects in the Japanese, although relatively modest in size, and independently of increased adiposity.

Roles of TauT and system A in cytoprotection of rat syncytiotrophoblast cell line exposed to hypertonic stress.

The purpose of this study was to clarify the cytoprotective mechanism(s) induced in a conditionally immortalized syncytiotrophoblast cell line (TR-TBT 18d-1) exposed to hypertonic conditions. Hypertonicity-induced apoptosis of TR-TBT 18d-1 cells, but this was blocked by addition of 1 mM taurine to the culture medium. TauT-knockdown using siRNA revealed that TauT is a major contributor to taurine uptake by TR-TBT 18d-1 cells, at least under normal conditions. Cellular uptake of [(3)H]taurine and [(14)C]betaine by TR-TBT 18d-1 cells cultured under hypertonic conditions was increased compared to that under normal conditions. TauT, BGT-1, ATA2 and HSP70 mRNAs were upregulated by hypertonicity, while OCTN2, ENT1 and CNT1 mRNAs were downregulated. [(3)H]Taurine uptake was strongly inhibited by TauT inhibitors such as hypotaurine and ß-alanine. MeAIB, a system A specific substrate, inhibited hypertonic stress-induced [(14)C]betaine uptake. These results suggest that TauT and system A play cytoprotective roles in syncytiotrophoblasts exposed to hypertonic stress.

Common variants at the GCK, GCKR, G6PC2-ABCB11 and MTNR1B loci are associated with fasting glucose in two Asian populations.

AIMS/HYPOTHESIS: To test fasting glucose association at four loci recently identified or verified by genome-wide association (GWA) studies of European populations, we performed a replication study in two Asian populations. METHODS: We genotyped five common variants previously reported in Europeans: rs1799884 (GCK), rs780094 (GCKR), rs560887 (G6PC2-ABCB11) and both rs1387153 and rs10830963 (MTNR1B) in the general Japanese (n = 4,813) and Sri Lankan (n = 2,319) populations. To identify novel variants, we further examined genetic associations near each locus by using GWA scan data on 776 non-diabetic Japanese samples. RESULTS: Fasting glucose association was replicated for the five single nucleotide polymorphisms (SNPs) at p < 0.05 (one-tailed test) in South Asians (Sri Lankan) as well as in East Asians (Japanese). In fine-mapping by GWA scan data, we identified in the G6PC2-ABCB11 region a novel SNP, rs3755157, with significant association in Japanese (p = 2.6 x 10(-8)) and Sri Lankan (p = 0.001) populations. The strength of association was more prominent at rs3755157 than that of the original SNP rs560887, with allelic heterogeneity detected between the SNPs. On analysing the cumulative effect of associated SNPs, we found the per-allele gradients (beta = 0.055 and 0.069 mmol/l in Japanese and Sri Lankans, respectively) to be almost equivalent to those reported in Europeans. CONCLUSIONS/INTERPRETATION: Fasting glucose association at four tested loci was proven to be replicable across ethnic groups. Despite this overall consistency, ethnic diversity in the pattern and strength of linkage disequilibrium certainly exists and can help to appreciably reduce potential causal variants after GWA studies.

Clonally expanded T lymphocytes from atomic bomb survivors in vitro show no evidence of cytogenetic instability.

Abstract Genomic instability has been suggested as a mechanism by which exposure to ionizing radiation can lead to cancer in exposed humans. However, the data from human cells needed to support or refute this idea are limited. In our previous study on clonal lymphocyte populations carrying stable-type aberrations derived from A-bomb survivors, we found no increase in the frequency of sporadic additional aberrations among the clonal cell populations compared with the spontaneous frequency in vivo. That work has been extended by using multicolor FISH (mFISH) to quantify the various kinds of chromosome aberrations known to be indicative of genomic instability in cloned T lymphocytes after they were expanded in culture for 25 population doublings. The blood T cells used were obtained from each of two high-dose-exposed survivors (>1 Gy) and two control subjects, and a total of 66 clonal populations (36 from exposed and 30 from control individuals) were established. For each clone, 100 metaphases were examined. In the case of exposed lymphocytes, a total of 39 additional de novo stable, exchange-type aberrations [translocation (t) + derivative chromosome (der)] were found among 3600 cells (1.1%); the corresponding value in the control group was 0.6% (17/3000). Although the ratio (39/3600) obtained from the exposed cases was greater than that of the controls (17/3000), the difference was not statistically significant (P = 0.101). A similar lack of statistical difference was found for the total of all structural chromosome alterations including t, der, dicentrics, duplications, deletions and fragments (P = 0.142). Thus there was no clear evidence suggesting the presence of chromosome instabilities among the clonally expanded lymphocytes in vitro from A-bomb survivors.

Influx mechanism of 2',3'-dideoxyinosine and uridine at the blood-placenta barrier.

The blood-placenta barrier (BPB) serves to protect the fetus from exposure to toxins, and to transport various nutrients, including nucleosides, and hormones from mother to fetus. It is known that nucleoside transporters contribute to the transfer of nucleosides and nucleoside analogues. 2',3'-Dideoxyinosine (ddI) has a nucleoside structure, and crosses the BPB. Although ddI is a substrate of several transporters, including equilibrative nucleoside transporters (ENT1 and ENT2), the transport mechanism of ddI in the placenta has not yet been characterized. Therefore, the purpose of this study was to clarify the influx mechanisms of ddI from the maternal to the fetal side, and to examine the interaction between ddI and uridine transport at the BPB. We studied ddI and uridine uptakes using a conditionally immortalized rat syncytiotrophoblast cell line, TR-TBT 18d-1, as a BPB model. The ddI uptake was temperature-dependent, Na(+)-independent and saturable. Kinetic analysis yielded K(m) values for ddI and uridine of 6.51 mM and 23.4 microM, respectively. Uridine uptake was inhibited by ENT1 and ENT2 substrates, and ddI uptake was also inhibited by substrates or inhibitors at concentrations that inhibit ENT2. Uridine uptake in Xenopus laevis oocytes expressing rat ENT2 was inhibited by 5mM ddI, in agreement with the results for TR-TBT 18d-1. Our results indicate that ddI and uridine are both taken up in part via ENT2 in TR-TBT 18d-1 cells, and therefore that ENT2 may contribute to their uptake at the BPB.

Potential of various drugs to inhibit nucleoside uptake in rat syncytiotrophoblast cell line, TR-TBT 18d-1.

The placenta requires nucleosides as nutrients for fetal growth, so it is important to examine potential interactions between placental transports of nucleosides and drugs to ensure the safety of pharmacotherapy during pregnancy. The purposes of this study are to clarify the uptake mechanisms of nucleosides from the maternal side of the syncytiotrophoblast and to investigate the inhibitory effect of various drugs on nucleoside uptake, using the rat syncytiotrophoblast cell line TR-TBT 18d-1, which shows syncytial-like morphology and functional expression of several transporters. Initial uptake of [(3)H]uridine or [(3)H]adenosine from the apical side of TR-TBT 18d-1 was markedly reduced by an excess of the respective unlabelled compound, and was slightly reduced by replacement of Na(+) with N-methyl-d-glucamine, indicating that both uptakes were Na(+)-independent. [(3)H]Uridine and [(3)H]adenosine uptakes in the absence of Na(+) were significantly and concentration-dependently inhibited by both 0.1 microM and 100 microM nitrobenzylthioinosine, suggesting the involvement of equilibrative nucleoside transporters (ENTs, SLC29). Kinetic analysis of adenosine uptake yielded a K(m) value of approximately 17 microM. These results are consistent with the reported uptake characteristics of uridine and adenosine by ENT1 and ENT2. The uptakes were significantly reduced by high concentrations of several nucleoside drugs, including cytarabine, vidarabine, zidovudine, mizoribine, caffeine and amitriptyline, but the effects were small within the therapeutic concentration ranges. In summary, our results suggest that ENTs are involved in apical uptake of uridine and adenosine in the syncytiotrophoblast. However, therapeutic concentrations of the drugs tested in this study might have little influence on maternal-to-fetal nucleoside transfer.

Characterization of the mechanism of zidovudine uptake by rat conditionally immortalized syncytiotrophoblast cell line TR-TBT.

PURPOSE: To characterize the uptake mechanism of zidovudine (AZT), a nucleoside reverse transcriptase inhibitor, in syncytiotrophoblast cells using the TR-TBT 18d-1 cell line previously established by our group. MATERIALS AND METHODS: The effects of several transporter inhibitors on the initial and steady-state apical uptake of AZT by TR-TBT 18d-1 were characterized, in order to identify the transporter(s) involved. RESULTS: Initial uptake of AZT was sodium-independent and saturable; the K(m) value was about 16 microM. Nitrobenzylthioinosine (NBMPR), probenecid and cimetidine each had little effect on the saturable AZT uptake, indicating that well characterized transporters, such as organic anion transporters (OATs and OATPs), organic cation transporters (OCTs) and equilibrative nucleoside transporters (ENTs), are not involved. However, thymidine and 2'-deoxyuridine strongly inhibited AZT uptake. These results suggest that an unidentified nucleoside uptake transporter is responsible for the uptake of AZT. Cyclosporin A, Ko143 and probenecid had little effect on AZT accumulation by TR-TBT 18d-1 cells, suggesting that transporter-mediated efflux of AZT is not substantial. CONCLUSION: Our results indicate that saturable AZT uptake into TR-TBT 18d-1 is mediated by a so-far-unidentified transporter.

Prevalence of Sjogren syndrome among Nagasaki atomic bomb survivors.

OBJECTIVES: Through a comprehensive epidemiological study, we determined Sjögren syndrome (SS) prevalence and examined the association between SS and ionising radiation dose. METHODS: A total of 1008 atomic bomb survivors in Nagasaki agreed to undergo the tests comprising a questionnaire for xerophthalmia and xerostomia, Schirmer-I test, Saxon test, and tests of anti-SS-A/Ro and anti-SS-B/La antibodies, and, if necessary, Rose Bengal stain test, salivary ultrasonographic and MRI examination from November 2002 through October 2004. Diagnosis of SS was based on the American-European Consensus Group criteria, or a modified version thereof. RESULTS: Among the 1008 participants (male 398, female 610, average age 71.6 years), 154 participants (15.3%) complained of xerophthalmia, and 264 (26.2%) of xerostomia. Reduced tear flow as assessed by the Schirmer-I test was detected in 371 of 992 participants (37.4%) and reduced saliva flow as assessed by the Saxon test in 203 of 993 participants (20.4%). Among all participants, 38 (3.8%) and 10 (1.0%) participants tested positive for anti-SS-A/Ro and anti-SS-B/La antibodies, respectively. Taking into consideration all the results, 23 participants were diagnosed with SS (primary 20, secondary 3), yielding a prevalence of 2.3%. Although the association between SS and radiation dose was not significant, radiation dose was significantly associated with hyposalivation. CONCLUSIONS: The present comprehensive epidemiological study reveals that the prevalence of SS was 2.3% among Nagasaki atomic bomb survivors and was not associated with radiation dose. The association between radiation dose and hyposalivation supported the possibility that radiation exposure damaged salivary gland function.

Historical height loss, vertebral deformity, and health-related quality of life in Hiroshima cohort study.

UNLABELLED: Height loss and vertebral deformity had independent effects on health-related quality of life evaluated by the European quality-of-life five-domain questionnaire (EQ-5D) in a cohort of 2,021 elderly Japanese men and women. Height loss aggravated EQ-5D more strongly than vertebral deformity in all domains, with different patterns. INTRODUCTION: Vertebral deformity reduces the activities of daily living and quality of life, and elevates mortality. Height loss is taken to be a sign of vertebral deformity, although other factors could also cause height loss. In this study, we examined the difference in EQ-5D between elderly with height loss and with vertebral deformity. METHODS: The subjects were 2,021 men and women aged 57-101 years from the Hiroshima Cohort who underwent health examinations in 2002-03 and responded to the EQ-5D. Vertebral deformity was assessed semi-quantitative methods using lateral chest and spine radiographs. Height was measured during the routine biennial examinations, which have been conducted since 1958. We used linear regression analyses, ordered polytomous logistic regression analyses, and Bonferroni tests. RESULTS: Eighty three men and 314 women had prevalent vertebral deformity. The mean height loss was 2.2 cm for men and 3.9 cm for women. Height loss > or =4 cm (P < 0.01) and vertebral deformity (P = 0.04) were independent risk factors for low EQ-5D scores, after adjustment for sex and age. CONCLUSIONS: The present study showed that height loss and vertebral deformity affected EQ-5D significantly and independently in the elderly.

Chromosome aberrations do not persist in the lymphocytes or bone marrow cells of mice irradiated in utero or soon after birth.

Mice were exposed at various ages to 1 Gy or 2 Gy of X rays, and translocation frequencies in peripheral blood T cells, spleen cells, and bone marrow cells were determined with FISH painting of chromosomes 1 and 3 when the animals were 20 weeks old. It was found that the mean translocation frequencies were very low (< or =0.8%) in mice exposed in the fetal or early postnatal stages. However, with the increase in animal age at the time of irradiation, the frequency observed at 20 weeks old became progressively higher then reached a plateau (about 5%) when mice were irradiated when > or =6 weeks old. A major role of p53 (Trp53)-dependent apoptosis for elimination of aberrant cells was not suggested because irradiated fetuses, regardless of the p53 gene status, showed low translocation frequencies (1.8% in p53(-/-) mice and 1.4% in p53(+/-) mice) compared to the frequency in the p53(-/-) mother (7.4%). In contrast, various types of aberrations were seen in spleen and liver cells when neonates were examined shortly after irradiation, similar to what was observed in bone marrow cells after irradiation in adults. We interpreted the results as indicating that fetal cells are generally sensitive to induction of chromosome aberrations but that the aberrant cells do not persist because fetal stem cells tend to be free of aberrations and their progeny replace the pre-existing cell populations during the postnatal growth of the animals.

Hepatocyte growth factor and c-Met expression in pericytes: implications for atherosclerotic plaque development.

Intraplaque neovascularization contributes to the progression of atherosclerosis. Our aim is to understand the mobilization of cells and factors involved in this process. We investigated the localization of hepatocyte growth factor (HGF) and its receptor, c-Met, in human atherosclerotic plaques, together with the effects of HGF on pericyte migration in vitro. Atherosclerotic femoral arterial segments were collected and analysed from 13 subjects who were undergoing lower limb amputation. Pericytes were identified in human lesions using a 3G5 antibody. Immunohistochemical analysis localized HGF mainly around microvessels, in association with some, but not all, CD31-positive endothelial cells. c-Met expression was mainly associated with smooth muscle cells and pericytes, around some, but not all, microvessels within the atherosclerotic lesions; no detection was apparent in normal internal mammary arteries. Using RT-PCR, we demonstrated expression of HGF and c-Met in a rat pericyte cell-line, TR-PCT1, and in primary pericytes. HGF treatment of TR-PCT1 cells induced their migration, but not their proliferation, in a dose-dependent manner (10-100 ng/ml, p<0.01), an effect mediated by activation of the serine/threonine kinase Akt, shown by western blot analysis. Treating the cells with the PI3K inhibitors Wortmannin (0.1 microM) or LY294002 (10 microM) abolished these effects. This work demonstrates the expression of c-Met and HGF in human atherosclerotic arteries, in association with SM-actin-positive cells and CD-31-positive cells, respectively. HGF induces pericyte migration via PI3-kinase and Akt activation in vitro. HGF and c-Met may be involved in neovascularization during plaque development, and may recruit pericytes to neovessels. Since pericytes are thought to mechanically stabilize new blood vessels, these factors may function to protect against haemorrhage.