Mouse transient receptor potential melastatin 2 (TRPM2) isoform 7 attenuates full-length mouse TRPM2 activity through reductions in its expression by targeting it to ER-associated degradation.

Transient receptor potential melastatin 2 (TRPM2) assembles into tetramers to function as an oxidative stress-sensitive Ca2+ channel at the surface membrane. Limited information is currently available on the 10 protein isoforms of mouse TRPM2 (mTRPM2) identified. This study investigated whether these isoforms function as Ca2+ channels and examined their effects on full-length mTRPM2 activity using the HEK 293 cell exogenous expression system. Only full-length mTRPM2, isoform 1 localized to the surface membrane and was activated by oxidative stress. Isoform 7 was clearly recognized by protein quality control systems and degraded by endoplasmic reticulum-associated degradation after transmembrane proteolysis. In the co-expression system, the activation and expression of full-length mTRPM2 were attenuated by its co-expression with isoform 7, but not with the other isoforms. This decrease in the expression of full-length mTRPM2 was recovered by the proteasomal inhibitor. The present results suggest that isoforms other than isoform 1 did not function as oxidative stress-sensitive channels and also that only isoform 7 attenuated the activation of full-length mTRPM2 by targeting it to endoplasmic reticulum-associated degradation. The present study will provide important information on the functional nature of mTRPM2 isoforms for the elucidation of their roles in physiological and patho-physiological responses in vivo using mouse models.

Possible involvement of TRPM2 activation in 5-fluorouracil-induced myelosuppression in mice.

Transient receptor potential melastatin 2 (TRPM2) is an oxidative stress-sensitive Ca2+-permeable channel. The activation of TRPM2 by H2O2 causes cell death in various types of cells. 5-Fluorouracil (5-FU) is an important anticancer drug, but myelosuppression is one of the most frequent adverse effects. The involvement of oxidative stress in 5-FU-induced myelosuppression has been reported, and bone marrow cells are known to express TRPM2. The aim of this study was to investigate whether TRPM2 is involved in 5-FU-induced myelosuppression. Enhancement of H2O2-induced intracellular Ca2+ concentration ([Ca2+]i) increase by 5-FU treatment was observed in human embryonic kidney 293 (HEK) cells stably expressing TRPM2 but not in HEK cells, indicating that 5-FU stimulates TRPM2 activation. In CD117 positive cells from wild type (WT) mouse bone marrow, 5-FU also enhanced the H2O2-induced [Ca2+]i increases, but not in cells from Trpm2 knockout (KO) mice. In the CFU-GM colony assay, the 5-FU-induced reduction of colony number was alleviated by Trpm2 deficiency. Moreover, the reduction of leukocytes in blood by administration with 5-FU in WT mice was also alleviated in Trpm2 KO mice. The activation of TRPM2 in bone marrow cells seems to be involved in 5-FU-induced myelosuppression.

Short TRPM2 prevents the targeting of full-length TRPM2 to the surface transmembrane by hijacking to ER associated degradation.

Membrane proteins are targeted to the surface transmembrane after folding and assembling in the endoplasmic reticulum (ER). Misfolded- and unassembled-proteins are degraded by proteasomes following ubiquitination, termed ER-associated degradation (ERAD). Transient receptor potential melastatin 2 (TRPM2) is an oxidative stress-sensitive channel. One of the TRPM2 splicing variants, short TRPM2 (TRPM2-S) having only the N-terminus and first two transmembrane domains, was reported to prevent full-length TRPM2 (TRPM2-L) activation. Although TRPM2-S interacts with TRPM2-L, the inhibitory mechanisms of TRPM2-S are unclear. We found that TRPM2-S prevents transmembrane expression of TRPM2-L by targeting ERAD. TRPM2-S expression was lower than that of TRPM2-L, and was increased by an ERAD inhibitor. TRPM2-S was not expressed at the transmembrane. This suggests that TRPM2-S is a substrate for ERAD. Upon the simultaneous expression of TRPM2-S, the transmembrane expression of TRPM2-L was attenuated and the poly-ubiquitination of TRPM2-L was facilitated. Our study may clarify why TRPM2-S inhibits oxidative stress-induced TRPM2-L activation.

Protective Effects of Duloxetine against Cerebral Ischemia-Reperfusion Injury via Transient Receptor Potential Melastatin 2 Inhibition.

Activation of transient receptor potential melastatin 2 (TRPM2), an oxidative stress-sensitive Ca2+-permeable channel, contributes to the aggravation of cerebral ischemia-reperfusion (CIR) injury. Recent studies indicated that treatment with the antidepressant duloxetine for 24 hours (long term) attenuates TRPM2 activation in response to oxidative stress in neuronal cells. To examine the direct effects of antidepressants on TRPM2 activation, we examined their short-term (0-30 minutes) treatment effects on H2O2-induced TRPM2 activation in TRPM2-expressing human embryonic kidney 293 cells using the Ca2+ indicator fura-2. Duloxetine exerted the strongest inhibitory effects on TRPM2 activation among the seven antidepressants tested. These inhibitory effects appeared to be due to the inhibition of H2O2-induced TRPM2 activation via an open-channel blocking-like mechanism, because duloxetine reduced the sustained phase but not the initial phase of increases in intracellular Ca2+ concentrations. In a whole-cell patch-clamp study, duloxetine reduced the TRPM2-mediated inward current during the channel opening state. We also examined the effects of duloxetine in a mouse model of CIR injury. The administration of duloxetine to wild-type mice attenuated CIR injury, similar to that in Trpm2 knockout (KO) mice. The administration of duloxetine did not reduce CIR injury further in Trpm2 KO mice, suggesting that it exerts neuroprotective effects against CIR injury by inhibiting TRPM2 activation. Regarding drug repositioning, duloxetine may be a useful drug in reperfusion therapy for ischemic stroke because it has already been used clinically in therapeutics for several disorders, including depression.

Tyrphostin AG-related compounds attenuate H2O2-induced TRPM2-dependent and -independent cellular responses.

PURPOSE: TRPM2 is a Ca2+-permeable channel that is activated by H2O2. TRPM2-mediated Ca2+ signaling has been implicated in the aggravation of inflammatory diseases. Therefore, the development of TRPM2 inhibitors to prevent the aggravation of these diseases is expected. We recently reported that some Tyrphostin AG-related compounds inhibited the H2O2-induced activation of TRPM2 by scavenging the intracellular hydroxyl radical. In the present study, we examined the effects of AG-related compounds on H2O2-induced cellular responses in human monocytic U937 cells, which functionally express TRPM2. METHODS: The effects of AG-related compounds on H2O2-induced changes in intracellular Ca2+ concentrations, extracellular signal-regulated kinase (ERK) activation, and CXCL8 secretion were assessed using U937 cells. RESULTS: Ca2+ influxes via TRPM2 in response to H2O2 were blocked by AG-related compounds. AG-related compounds also inhibited the H2O2-induced activation of ERK, and subsequent secretion of CXCL8 mediated by TRPM2-dependent and -independent mechanisms. CONCLUSION: Our results show that AG-related compounds inhibit H2O2-induced CXCL8 secretion following ERK activation, which is mediated by TRPM2-dependent and -independent mechanisms in U937 cells. We previously reported that AG-related compounds blocked H2O2-induced TRPM2 activation by scavenging the hydroxyl radical. The inhibitory effects of AG-related compounds on TRPM2-independent responses may be due to scavenging of the hydroxyl radical.

Significance of TRP channels in oxidative stress.

Reactive oxygen species induce oxidative stress, leading to cell damage, but also function as signal transduction molecules. Transient receptor potential (TRP) channels have been attracting increasing attention as Ca2+-permeable channels that sense environmental changes. The members of one class of TRP channels have emerged as reactive oxygen species sensors. The significance of Ca2+ signaling induced by the activation of reactive oxygen species-sensitive TRP channels under pathological conditions is currently being elucidated. The selective inhibition of reactive oxygen species-sensitive TRP channels represents a future challenge that may lead to new therapeutic strategies for the suppression of reactive oxygen species-related diseases.

Targeting TRPM2 in ROS-Coupled Diseases.

Under pathological conditions such as inflammation and ischemia-reperfusion injury large amounts of reactive oxygen species (ROS) are generated which, in return, contribute to the development and exacerbation of disease. The second member of the transient receptor potential (TRP) melastatin subfamily, TRPM2, is a Ca(2+)-permeable non-selective cation channel, activated by ROS in an ADP-ribose mediated fashion. In other words, TRPM2 functions as a transducer that converts oxidative stress into Ca(2+) signaling. There is good evidence that TRPM2 plays an important role in ROS-coupled diseases. For example, in monocytes the influx of Ca(2+) through TRPM2 activated by ROS contributes to the aggravation of inflammation via chemokine production. In this review, the focus is on TRPM2 as a molecular linker between ROS and Ca(2+) signaling in ROS-coupled diseases.

Inhibitory effects of Tyrphostin AG-related compounds on oxidative stress-sensitive transient receptor potential channel activation.

Some transient receptor potential (TRP) proteins including TRPA1, TPRM2 and TRPV1 are oxidative stress-sensitive Ca(2+)-permeable channels. Ca(2+) signaling via these TRP channels activated by oxidative stress has been implicated in the aggravation of various inflammatory diseases and pain sensation. We recently reported that Tyrphostin AG490 exerted inhibitory effects on H2O2-induced TRPM2 activation by scavenging the hydroxyl radical. In order to identify stronger inhibitors of oxidative stress-sensitive TRP channels than AG490, we examined the inhibitory effects of Tyrphostin AG-related compounds on H2O2-induced TRP channel activation in human embryonic kidney 293 cells expressing TRP channels. AG555 and AG556 blocked the activation of TRPM2 by H2O2 more strongly than AG490. Regarding TRPV1 and TRPA1, none of the three compounds tested affected H2O2-induced TRPV1 activation; however, AG555 and AG556 reduced H2O2-induced TRPA1 activation more than AG490. Thus, we herein identified AG555 and AG556 as new compounds that exert stronger inhibitory effects on H2O2-induced TRPM2 and TRPA1 activation than AG490. Edaravone, a hydroxyl radical scavenger used in the treatment of cerebral hemorrhage and cerebral infarction, did not affect H2O2-induced TRPM2 or TRPA1 activation. AG555 and AG556 may be useful seed compounds as therapeutic agents for several TRP-related diseases associated with oxidative stress.

TRPM2 channels in alveolar epithelial cells mediate bleomycin-induced lung inflammation.

Lung inflammation is a major adverse effect of therapy with the antitumor drug bleomycin (BLM). Transient receptor potential melastatin 2 (TRPM2) is a Ca(2+)-permeable channel that is activated by oxidative stress through the production of ADP-ribose. We herein investigated whether TRPM2 channels contributed to BLM-induced lung inflammation. The intratracheal instillation of BLM into wild-type (WT) mice increased the number of polymorphonuclear leukocytes (PMNs) and inflammatory cytokine levels in the lung. Increases in inflammatory markers in WT mice were markedly reduced in trpm2 knockout (KO) mice, which demonstrated that the activation of TRPM2 channels was involved in BLM-induced lung inflammation. The expression of TRPM2 mRNA was observed in alveolar macrophages, alveolar epithelial cells, and lung fibroblasts. Actually, TRPM2 protein was expressed in lung tissues. Of these, TRPM2 channels in epithelial cells were activated by the addition of H2O2 following a BLM pretreatment, resulting in the secretion of macrophage inflammatory protein-2 (MIP-2). The H2O2-induced activation of TRPM2 by the BLM pretreatment was blocked by the poly(ADP-ribose) polymerase (PARP) inhibitors PJ34 and 3-aminobenzamide. The accumulation of poly(ADP-ribose) in the nucleus, a marker for ADP-ribose production, was strongly induced by H2O2 following the BLM pretreatment. Furthermore, administration of PRAP inhibitors into WT mice markedly reduced recruitment of inflammatory cells and MIP-2 secretion induced by BLM instillation. These results suggest that the induction of MIP-2 secretion through the activation of TRPM2 channels in alveolar epithelial cells is an important mechanism in BLM-induced lung inflammation, and the TRPM2 activation is likely to be mediated by ADP-ribose production via PARP pathway. TRPM2 channels may be new therapeutic target for BLM-induced lung inflammation.

Chemotherapy-induced neutropenia as a prognostic factor in patients with unresectable pancreatic cancer.

PURPOSE: We conducted a retrospective cohort study to examine whether neutropenia could be an indicator of good prognosis in patients treated with gemcitabine (GEM) for unresectable pancreatic cancer. METHODS: A total of 178 patients with unresectable pancreatic cancer, who were treated with first-line (n = 121) or second-line (n = 57) GEM, were included in our analyses. A Cox proportional hazard model was used to examine the effect of the grade of GEM-induced neutropenia on prognosis. Furthermore, the difference in survival time for each grade was assessed using a log-rank test. RESULTS: In the first-line population, the hazard ratios of patients with grade 2 or grade 3 neutropenia compared with the ratios of those without neutropenia (grade 0) were 0.43 (95% CI 0.27-0.70) and 0.37 (0.21-0.65), respectively (p < 0.05). The median survival time (MST) was 3.8 months for grade 0, 9.4 months for grade 2, and 10.1 for grade 3. Landmark analysis of the second-line population revealed a hazard ratio of 0.52 (0.30-0.82) for grade 1 and 0.49 for grade 2 (0.28-0.72) (p < 0.05). MST was 1.3 months for grade 0, 4.7 months for grade 1, and 4.6 months for grade 2. CONCLUSIONS: We found that neutropenia grade was an indicator of good prognosis in patients treated with first-line and second-line GEM for unresectable pancreatic cancer. A prospective study should be performed to examine whether dosage adjustment using neutropenia grade as an indicator would improve prognosis.

Sensitization of H2O2-induced TRPM2 activation and subsequent interleukin-8 (CXCL8) production by intracellular Fe(2+) in human monocytic U937 cells.

Transient receptor potential melastatin 2 (TRPM2) is an oxidative stress-sensitive Ca(2+)-permeable channel. In monocytes/macrophages, H2O2-induced TRPM2 activation causes cell death and/or production of chemokines that aggravate inflammatory diseases. However, relatively high concentrations of H2O2 are required for activation of TRPM2 channels in vitro. Thus, in the present study, factors that sensitize TRPM2 channels to H2O2 were identified and subsequent physiological responses were examined in U937 human monocytes. Temperature increase from 30°C to 37°C enhanced H2O2-induced TRPM2-mediated increase in intracellular free Ca(2+) ([Ca(2+)]i) in TRPM2-expressing HEK 293 cells (TRPM2/HEK cells). The H2O2-induced TRPM2 activation enhanced by the higher temperature was dramatically sensitized by intracellular Fe(2+)-accumulation following pretreatment with FeSO4. Thus intracellular Fe(2+)-accumulation sensitizes H2O2-induced TRPM2 activation at around body temperature. Moreover, intracellular Fe(2+)-accumulation increased poly(ADP-ribose) levels in nuclei by H2O2 treatment, and the sensitization of H2O2-induced TRPM2 activation were almost completely blocked by poly(ADP-ribose) polymerase inhibitors, suggesting that intracellular Fe(2+)-accumulation enhances H2O2-induced TRPM2 activation by increase of ADP-ribose production through poly(ADP-ribose) polymerase pathway. Similarly, pretreatment with FeSO4 stimulated H2O2-induced TRPM2 activation at 37°C in U937 cells and enhanced H2O2-induced ERK phosphorylation and interleukin-8 (CXCL8) production. Although the addition of H2O2 to cells under conditions of intracellular Fe(2+)-accumulation caused cell death, concentration of H2O2 required for CXCL8 production was lower than that resulting in cell death. These results indicate that intracellular Fe(2+)-accumulation sensitizes TRPM2 channels to H2O2 and subsequently produces CXCL8 at around body temperature. It is possible that sensitization of H2O2-induced TRPM2 channels by Fe(2+) may implicated in hemorrhagic brain injury via aggravation of inflammation, since Fe(2+) is released by heme degradation under intracerebral hemorrhage.

Practical prognostic index for survival in patients with unresectable pancreatic cancer treated with gemcitabine or S-1.

BACKGROUND/AIMS: We performed this retrospective cohort study to identify prognostic factors for unresectable pancreatic cancer treated with current standard therapy using gemcitabine (GEM) or S-1 and to stratify patients prior to treatment using a prognostic index (PI). METHODOLOGY: We analyzed 182 patients with unresectable pancreatic cancer, who had received GEM or S-1 as first-line chemotherapy. Factors that contributed to the prognosis were identified by univariate and multivariate analysis using a Cox proportional hazards model. The PI was constructed using the factors identified in the multivariate analysis. RESULTS: By multivariate analysis, performance status (PS), stage, and absolute neutrophil count (ANC) were identified as factors that independently contributed to the prognosis of unresectable pancreatic cancer (P < 0.05). The hazard ratios were 1.69, 3.33, and 1.18, respectively. In addition, PI was calculated using these three factors. Patients were classified into three groups according to the PI values. A significant difference was observed among the survival curves of these three groups (P < 0.05). CONCLUSIONS: We identified three prognostic factors in the population after the introduction of S-1, and have created a simple and useful PI. This index demonstrates the ability to accurately classify advanced pancreatic cancer patients before the start of treatment.

Inhibitory effects of AG490 on H2O2-induced TRPM2-mediated Ca(2+) entry.

Transient receptor potential melastatin 2 (TRPM2) is an oxidative stress-sensitive Ca(2+)-permeable channel that controls Ca(2+) signalling. The activation of Janus kinase 2 (Jak2) by oxidative stress is implicated in the production of inflammatory mediators. We found that AG490, a Jak2 inhibitor, had an inhibitory effect on H2O2-induced TRPM2 activation. The purpose of this study was to examine the underlying mechanisms of the inhibitory effects of AG490. Activation of TRPM2 in TRPM2-expressing human embryonic kidney 293 (TRPM2/HEK) cells or the human monocytic cell line U937 was monitored by fluorescence-based Ca(2+) imaging and patch-clamp techniques. Treatment with AG490 almost completely blocked H2O2-induced increase in intracellular Ca(2+) in TRPM2/HEK and U937 cells. In the patch-clamp study, AG490 inhibited the H2O2-evoked inward current but not the ADP-ribose-induced inward current in TRPM2/HEK cells. In contrast, Jak inhibitor 1 (pyridone 6) and staurosporine, both of which inhibit Jak2, had no effect on H2O2-induced increase in intracellular Ca(2+). Moreover, AG490 decreased intracellular reactive oxygen species level, which was measured by using a hydroperoxide-sensitive fluorescent dye, on incubation with H2O2. In the cell-free assay system, AG490 scavenged hydroxyl radicals but not H2O2. These findings indicate that AG490 significantly reduces H2O2-induced TRPM2 activation, presumably by scavenging hydroxyl radicals rather than Jak2-dependent mechanisms. Although transient receptor potential ankyrin 1 (TRPA1) channel is also activated by H2O2, the H2O2-induced Ca(2+) entry through TRPA1 was only slightly delayed by AG490. This validates the potential use of AG490, as one of the materials for characterizing the role of TRPM2 channels in pathological models.

TRPs as chemosensors (ROS, RNS, RCS, gasotransmitters).

The transient receptor potential (trp) gene superfamily encodes TRP proteins that act as multimodal sensor cation channels for a wide variety of stimuli from outside and inside the cell. Upon chemical or physical stimulation of cells, TRP channels transduce electrical and/or Ca(2+) signals via their cation channel activities. These functional features of TRP channels allow the body to react and adapt to different forms of environmental changes. Indeed, members of one class of TRP channels have emerged as sensors of reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive carbonyl species (RCS), and gaseous messenger molecules including molecular oxygen (O2), hydrogen sulfide (H2S), and carbon dioxide (CO2). Hydrogen peroxide (H2O2), an ROS, triggers the production of ADP-ribose, which binds and activates TRPM2. In addition to TRPM2, TRPC5, TRPV1, and TRPA1 are also activated by H2O2 via modification of cysteine (Cys) free sulfhydryl groups. Nitric oxide (NO), a vasoactive gaseous molecule, regulates TRP channels directly via Cys S-nitrosylation or indirectly via cyclic GMP (cGMP)/protein kinase G (PKG)-dependent phosphorylation. Anoxia induced by O2-glucose deprivation and severe hypoxia activates TRPM7 and TRPC6, respectively, whereas TRPA1 serves as a sensor of mild hypoxia and hyperoxia in vagal and sensory neurons. TRPA1 also detects other gaseous molecules, such as hydrogen sulfide (H2S) and carbon dioxide (CO2). In this review, we highlight our current knowledge of TRP channels as chemosensors for ROS, RNS, RCS, and gaseous molecules and discuss their functional impacts on physiological and pathological events.

Involvement of TRPM2 and L-type Ca²âº channels in Ca²âº entry and cell death induced by hydrogen peroxide in rat ß-cell line RIN-5F.

Ca²âº overload is one of the mechanisms for H2O2-induced cell death in rat pancreatic ß-cell line RIN-5F cells. RIN-5F cells express TRPM2, which is a Ca²âº-permeable channel activated by H2O2, and voltage-dependent L-type Ca²âº channels, both of which induce Ca²âº entry by H2O2. This study examined the contribution of these channels to H2O2-induced Ca²âº entry and cell death in RIN-5F cells. Cytosolic Ca²âº concentration was measured using fura-2 as a Ca²âº indicator. Cell death was estimated by trypan blue exclusion. Pre-treatment with poly(ADP-ribose) polymerase (PARP) inhibitors, which inhibit TRPM2 activation, strongly reduced Ca²âº entry by H2O2. The PARP inhibitors used had no effect on the Ca²âº elevation by voltage-dependent L-type Ca²âº channels. On the other hand, pre-treatment with L-type Ca²âº channel blockers, which did not affect TRPM2 activation, partly reduced H2O2-induced Ca²âº entry. Treatment with PARP inhibitors but not L-type Ca²âº channel blockers, around the early phase in H2O2-induced Ca²âº elevation, also reduced the late phase. Moreover, H2O2-induced RIN-5F cell death was strongly attenuated by PARP inhibitors, in compared to L-type Ca²âº channel blockers. Our results suggest that TRPM2 channels rather than L-type Ca²âº channels primarily contribute to H2O2-induced Ca²âº entry and cell death.

Influence of the Tohoku-Pacific Ocean earthquake and its aftershocks on the response to prophylactic therapy with lomerizine in patients with migraine in Tokyo: a retrospective study.

BACKGROUND: On March 11, 2011, the Tohoku-Pacific Ocean earthquake (magnitude 9.0) struck the eastern part of Japan. Despite being far from the epicenter of the catastrophic earthquake, the effects were strongly felt in Tokyo, and the aftershocks continued for several months. There are no reports regarding the influence of earthquakes on migraine medication. The aim of our study was to determine the impact of earthquakes on prophylactic therapy with lomerizine in patients with migraine in Tokyo. METHODS: The study included patients with migraine who were admitted to outpatient clinics in Tokyo between January 2010 and July 2010 or between January 2011 and July 2011 and who were prescribed lomerizine prophylactically for headache by specialists. We investigated clinical factors from the medical records for 26 of these patients. RESULTS: The study population included 10 patients in 2010 and 16 patients in 2011. The frequency of headaches was reduced to under 5 days/month during February in both the groups. Compared to 2010, the frequency of headaches significantly increased in 2011 in March, April and May. CONCLUSION: Patients with migraine were sensitive to exposure to the earthquake and their headaches worsened despite successful prophylactic treatment with lomerizine before the Tohoku-Pacific Ocean earthquake.

Potentiated macrophage activation by acid sensing under low adiponectin levels.

Adiponectin can protect against inflammation; one of the mechanisms involves direct, inhibition of macrophages (MΦ). We postulated that adiponectin anti-sense transgenic (AsTg) mice raised in our laboratory are prone to inflammation because of systemic low adiponectin levels. The writhing response to acetic acid was utilized as an in vivo inflammatory model, and using Ca(2)(+), response to the acid was exploited in vitro to evaluate the function of resident peritoneal MΦ. The in vivo response to the acid was increased and the Ca(2)(+) response of MΦ was enhanced in AsTg mice, compared with those in wild type (WT) mice. In parallel with these enhanced responses, MΦ from AsTg mice augmented TNF-α and IL-6 mRNA expression. We further analyzed the enhancement in activity of MΦ from AsTg mice by acid sensing using specific inhibitors, amiloride for acid-sensing ion channels (ASICs) and KB-R7943 for Na(+)/Ca(2)(+) exchangers (NCXs). Our results indicated that in AsTg mice, the Ca(2)(+) response to the acid was facilitated in MΦ by a low threshold of ASIC1 and NCX1 molecules and the activity of these channel was possibly regulated by adiponectin.

Characteristics of inconsistent responders to prophylaxis therapy with lomerizine in patients with migraine: a retrospective study in Japan.

Although lomerizine is used as a first-line prophylactic drug for migraines in Japan, approximately 30% of patients fail to respond to this treatment. On the basis of medical records, we investigated the involvement of clinical factors in response to lomerizine used in patients with migraine as primary headache and established a scoring system for predicting clinical responses to prophylactic therapy. Ninety-four consistent responders and 33 inconsistent responders to lomerizine were enrolled in this study. Multivariate stepwise logistic regression analysis revealed that migraine plus tension-type headache as primary headache and frequency of headache attacks were significant factors that contributed independently to negative response [odds ratio, 3.817 (no vs. yes; 95% confidence interval (CI), 1.264-11.628) and 5.814 (>15 episode days/month vs. 0-14 episode days/month; 95% CI, 2.381-14.286), respectively]. The predictive index (PI) of clinical responses to lomerizine in patients with migraine was calculated using the regression coefficients of two factors as an integer, where the score for inconsistent responders (1.00±0.71) was significantly higher than that for consistent responders (0.37±0.53, p<0.001). Sensibility of the low-scoring group (PI=0) was 75.8%, and specificity of the high-scoring group (PI=2) was 97.9%. Groups scoring low, intermediated and high included 11.6%, 35.4% and 80.0% of inconsistent responders, respectively. The PI value obtained might represent an appropriate scoring system to predict responses in these patients.

Decreased cardiac mitochondrial tetrahydrobiopterin in a rat model of pressure overload.

Sustained cardiac pressure overload induces mitochondrial dysfunction and apoptosis of cardiomyocytes leading to pathological cardiac hypertrophy and dysfunction. Mitochondrial nitric oxide synthase (NOS) appears to cause uncoupling, which produces reactive oxygen species (ROS) instead of nitric oxide (NO), by a decrease in the cofactor tetrahydrobiopterin (BH4). This study focused on examining the changes in mitochondrial BH4 levels during cardiac pressure overload. Chronic cardiac pressure overload was generated by abdominal aortic banding in rats. Levels of BH4 and its oxidized form were measured in the mitochondria isolated from the left ventricle (LV) and the post-mitochondrial supernatants. Chronic aortic banding increased blood pressure, and induced cardiac hypertrophy and fibrosis. Notably, the BH4 levels were decreased while its oxidized forms were increased in LV mitochondria, but not in the post-mitochondrial supernatants containing the cytosol and microsome. Anti-neuronal NOS antibody-sensitive protein was detected in the cardiac mitochondria. Moreover, continuous administration of BH4 to rats with pressure overload increased mitochondrial BH4 levels and reduced cardiac fibrosis and matrix metallopeptidase activity, but not cardiac hypertrophy. These findings show the possibility that NOS uncoupling by decreased cardiac mitochondrial BH4 levels is implicated, at least in part, in the development of cardiac fibrosis, leading to cardiac dysfunction induced by pressure overload.

Tryptophan hydroxylase 2 gene polymorphisms in Japanese patients with medication overuse headaches.

PURPOSE: We investigated whether tryptophan hydroxylase 2 (TPH2) gene polymorphisms were involved in the aggravation of migraines due to the overuse of medication. METHODS: Forty-seven migraine patients (6 males and 41 females; 36.4 10.3 years) and 22 MOH patients (1 male and 21 females; 39.6 9.9 years) who had migraines participated in this study. The genotypes for the TPH2 gene polymorphisms (rs4565946, rs4570625, and rs4341581) were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. RESULTS: The rs4565946, rs4570625, and rs4341581 genotypes were similarly distributed between migraine patients and MOH patients. CONCLUSION: The results of this study showed no association between tryptophan TPH2 gene polymorphisms and the complication of MOH in patients with migraines.