Cell density-dependent antibiotic tolerance to inhibition of the elongation machinery requires fully functional PBP1B.

The peptidoglycan (PG) cell wall provides shape and structure to most bacteria. There are two systems to build PG in rod shaped organisms: the elongasome and divisome, which are made up of many proteins including the essential MreB and PBP2, or FtsZ and PBP3, respectively. The elongasome is responsible for PG insertion during cell elongation, while the divisome is responsible for septal PG insertion during division. We found that the main elongasome proteins, MreB and PBP2, can be inhibited without affecting growth rate in a quorum sensing-independent density-dependent manner. Before cells reach a particular cell density, inhibition of the elongasome results in different physiological responses, including intracellular vesicle formation and an increase in cell size. This inhibition of MreB or PBP2 can be compensated for by the presence of the class A penicillin binding protein, PBP1B. Furthermore, we found this density-dependent growth resistance to be specific for elongasome inhibition and was consistent across multiple Gram-negative rods, providing new areas of research into antibiotic treatment.

Mechanism of Chronic Stress-Induced Glutamatergic Neuronal Damage in the Basolateral Amygdaloid Nucleus.

Stress is a ubiquitous part of our life, while appropriate stress levels can help improve the body's adaptability to the environment. However, sustained and excessive levels of stress can lead to the occurrence of multiple devastating diseases. As an emotional center, the amygdala plays a key role in the regulation of stress-induced psycho-behavioral disorders. The structural changes in the amygdala have been shown to affect its functional characteristics. The amygdala-related neurotransmitter imbalance is closely related to psychobehavioral abnormalities. However, the mechanism of structural and functional changes of glutamatergic neurons in the amygdala induced by stress has not been fully elucidated. Here, we identified that chronic stress could lead to the degeneration and death of glutamatergic neurons in the lateral amygdaloid nucleus, resulting in neuroendocrine and psychobehavioral disorders. Therefore, our studies further suggest that the Protein Kinase R-like ER Kinase (PERK) pathway may be therapeutically targeted as one of the key mechanisms of stress-induced glutamatergic neuronal degeneration and death in the amygdala.

Impact of aliphatic acyl and aromatic thioamide substituents on the anticancer activity of Ru(II)-p-cymene complexes with acylthiourea ligands-in vitro and in vivo studies.

Six different acylthiourea ligands (L1-L6) and their corresponding Ru(II)-p-cymene complexes (P1-P6) were designed to explore the structure-activity relationship of the complexes upon aliphatic chain and aromatic conjugation on the C- and N-terminals, respectively. The compounds were synthesized and adequately characterized using various analytical and spectroscopic techniques. The structures of P2-P6, solved using single crystal X-ray diffraction (XRD), confirmed the neutral monodentate coordination of the S atoms of the acylthiourea ligands to Ru(II) ions. In silico studies showed an increase of lipophilicity for the ligands with an increase in alkyl chain length or aromatic conjugation at the C- or N-terminal, respectively. Subsequently, mitogen-activated protein kinases (MAPK) were predicted as one of the primary targets for the complexes, which showed good binding affinity towards extracellular signal-regulated kinases (ERK1, ERK2 and ERK5), c-Jun N-terminal kinase (JNK) and p38 of the MAPK pathway. Henceforth, the complexes were tested for their anticancer activity in lung carcinoma (A549) and cisplatin-resistant lung carcinoma (cisA549R) cells and human umbilical vein epithelial normal cells (HUVEC). Interestingly, an increase in chain length or aromatic conjugation led to an increase in the activity of the complexes, with P5 (7.73 and 13.04 µM) and P6 (6.52 and 14.45 µM) showing the highest activity in A549 and cisA549R cells, which is better than the positive control, cisplatin (8.72 and 44.28 µM). Remarkably, we report the highest activity yet observed for complexes of the type [(η6-p-cymene)RuIICl2(S-acylthiourea)] in the tested cell lines. Aqueous solution studies showed that complexes P5 and P6 are rapidly hydrolyzed to produce solely aquated species that remained stable for 24 h. Staining assays and flow cytometric analyses of P5 and P6 in A549 cells revealed that the complexes induced apoptosis and arrested the cell cycle predominantly in the S phase. In vivo studies demonstrated the higher toxicity of cisplatin and a comparatively higher survival rate of mice injected with the most active complex P6. Histological analyses revealed that treatment with P6 at high doses of up to 8 mg kg-1 did not cause any palpable damage to the tested organs.

Suppression of alveolar bone resorption by salubrinal in a mouse model of periodontal disease.

AIMS: The relationship between stress to endoplasmic reticulum (ER) and periodontitis has been known, and ER stress induced by Porphyromonas gingivalis results in the loss of alveolar bone. Salubrinal is a small synthetic compound and attenuates ER stress through inhibition of de-phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α). In this study, we examined whether salubrinal attenuates periodontitis in a mouse model of experimental periodontal disease. MATERIALS AND METHODS: We evaluated loss of alveolar bone and attachment levels in periodontium using micro-computed tomography (µCT) and hematoxylin-eosin (HE) staining, respectively. Furthermore, we measured osteoclast numbers using tartrate-resistant acid phosphatase (TRAP) staining and osteoblast numbers using HE staining for bone resorption and for bone formation, respectively. To examine the inhibitory effects of salubrinal against pro-inflammatory cytokines, we measured TNF-α and IL1-ß score in periodontium using immunohistostaining. KEY FINDINGS: The results revealed that salubrinal suppressed loss of alveolar bone and attachment levels in periodontium induced by periodontitis. It decreased osteoclast numbers and increased osteoblasts. It also suppressed the expression levels of TNF-α in periodontium. SIGNIFICANCE: These results show that salubrinal alleviates periodontitis through suppression of alveolar bone resorption and the pro-inflammatory cytokine, and promotion of the bone formation. Since salubrinal has been shown to have these beneficial effects for periodontal disease, it may provide a novel therapeutic possibility for the disease.

Efficacy and safety of TAS-115, a novel oral multi-kinase inhibitor, in osteosarcoma: an expansion cohort of a phase I study.

Background osteosarcoma is a rare, primary malignant bone tumour with limited available treatments for advanced or recurrent disease, resulting in a poor prognosis for patients. TAS-115 is a novel tyrosine kinase inhibitor under investigation in a phase I study in patients with solid tumours. We report data of osteosarcoma patients in the expansion cohort of this ongoing study. Patients and methods an analysis of this multicentre, open-label study was performed 6 months after the final patient was enrolled, and included patients aged ≥15 years, with unresectable or recurrent osteosarcoma, and who had refractory to standard therapy or for whom no standard therapy was available. TAS-115 650 mg/day was orally administered in a 5 days on/2 days off schedule. Results a total of 20 patients with osteosarcoma were enrolled. The most common adverse drug reactions (ADRs) were neutrophil count decreased (75%), aspartate aminotransferase increased (50%), and platelet count decreased (50%); 85% of patients had grade ≥ 3 ADRs. Long-term disease control (>1 year) with TAS-115 was achieved in three patients. The best overall response was stable disease (50%); no patient achieved a complete or partial response. Median progression-free survival was 3 months; 4-month and 12-month progression-free rates were 42% and 31%, respectively. Conclusion the safety and tolerability of TAS-115 and long-term disease stability for patients with unresectable or recurrent osteosarcoma were confirmed in this study, suggesting that TAS-115 is a promising novel therapy for advanced osteosarcoma patients. Trial registration number: JapicCTI-132333 (registered on November 8, 2013).

Comparing mTOR inhibitor Rapamycin with Torin-2 within the RIST molecular-targeted regimen in neuroblastoma cells.

The prognosis for patients with relapsed or refractory high-risk neuroblastoma remains dismal and novel therapeutic options are urgently needed. The RIST treatment protocol has a multimodal metronomic therapy design combining molecular-targeted drugs (Rapamycin and Dasatinib) with chemotherapy backbone (Irinotecan and Temozolomide), which is currently verified in a phase II clinical trial (NCT01467986). With the availability of novel and more potent ATP competitive mTOR inhibitors, we expect to improve the RIST combination therapy. By comparing the IC50 values of Torin-1, Torin-2, AZD3147 and PP242 we established that only Torin-2 inhibited cell viability of all three MycN-amplified neuroblastoma cell lines tested at nanomolar concentration. Single treatment of both mTOR inhibitors induced a significant G1 cell cycle arrest and combination treatment with Dasatinib reduced the expression of cell cycle regulator cyclin D1 or increased the expression of cell cycle inhibitor p21. The combinatorial index depicted for both mTOR inhibitors a synergistic effect with Dasatinib. Interestingly, compared to Rapamycin, the combination treatment with Torin-2 resulted in a broader mTOR pathway inhibition as indicated by reduced phosphorylation of AKT (Thr308, Ser473), 4E-BP (Ser65), and S6K (Thr389). Furthermore, substituting Rapamycin in the modified multimodal RIST protocol with Torin-2 reduced cell viability and induced apoptosis despite a significant lower Torin-2 drug concentration applied. The efficacy of nanomolar concentrations may significantly reduce unwanted immunosuppression associated with Rapamycin. However, at this point we cannot rule out that Torin-2 has increased toxicity due to its potency in more complex systems. Nonetheless, our results suggest that including Torin-2 as a substitute for Rapamycin in the RIST protocol may represent a valid option to be evaluated in prospective clinical trials for relapsed or treatment-refractory high-risk neuroblastoma.

Nanoparticles Loaded with a New Thiourea Derivative: Development and In vitro Evaluation Against Leishmania amazonensis.

BACKGROUND: Leishmaniasis is a neglected tropical disease caused by protozoa of the genus Leishmania. Current treatments are restricted to a small number of drugs that display both severe side effects and a potential for parasites to develop resistance. A new N-(3,4-methylenedioxyphenyl)-N'- (2-phenethyl) thiourea compound (thiourea 1) has shown promising in vitro activity against Leishmania amazonensis with an IC50 of 54.14 µM for promastigotes and an IC50 of 70 µM for amastigotes. OBJECTIVE: To develop a formulation of thiourea 1 as an oral treatment for leishmaniasis, it was incorporated into Nanoparticles (NPs), a proven approach to provide long-acting drug delivery systems. METHODS: Poly (D,L-Lactic-co-Glycolic Acid) (PLGA) polymeric NPs containing thiourea 1 were obtained through a nanoprecipitation methodology associated with solvent evaporation. The NPs containing thiourea 1 were characterized for Encapsulation Efficiency (EE%), reaction yield (% w/w), surface charge, particle size and morphology by Transmission Electron Microscopy (TEM). RESULTS: NPs with thiourea 1 showed an improved in vitro leishmanicidal activity with a reduction in its cytotoxicity against macrophages (CC50>100 µg/mL) while preserving its IC50 against intracellular amastigotes (1.46 ± 0.09 µg/mL). This represents a parasite Selectivity Index (SI) of 68.49, which is a marked advancement from the reference drug pentamidine (SI = 30.14). CONCLUSION: The results suggest that the incorporation into NPs potentiated the therapeutic effect of thiourea 1, most likely by improving the selective delivery of the drug to the phagocytic cells that are targeted for infection by L. amazonensis. This work reinforces the importance of nanotechnology in the acquisition of new therapeutic alternatives for oral treatments.

Therapies for galactosemia: a patent landscape.

Galactosemia is the inherited inability to metabolise galactose. The most common results from a lack of galactose 1-phosphate uridylyltransferase activity. The current treatment, removal of galactose from the diet, is inadequate and often fails to prevent long-term complications. Since 2015, three patents have been filed describing novel therapies. These are: the use of aldose reductase inhibitors to reduce cataracts and, possibly, other symptoms; salubrinal to stimulate cellular stress responses; mRNA therapy to increase cellular galactose 1-phosphate uridylyltransferase activity. The viability of all three is supported by academic studies. The potential and drawbacks of all three are discussed and evaluated.

Histamine H4 receptor stimulation in the locus coeruleus attenuates neuropathic pain by promoting the coeruleospinal noradrenergic inhibitory pathway.

The locus coeruleus (LC) adrenergic nuclei constitute a pain-control inhibitory system nucleus implicated in descending modulation of pain through the action on spinal α2-adrenoceptors. Histaminergic innervation from the tuberomammillary nucleus of the LC increases firing of noradrenergic neurons and might contribute to pain control. Here we evaluated the contribution of LC histaminergic innervation in descending modulation of neuropathic hypersensitivity, by investigating the role of the histamine H4 receptor subtype in a mouse model of neuropathic pain. Intra LC administration of the H4 agonist VUF 8430 attenuated mechanical and thermal allodynia of mice that underwent spared nerve injury (SNI). Similarly, histamine in the LC showed mechanical and thermal anti-hypersensitivity. Pretreatment of LC with JNJ 10191584 (H4 antagonist) prevented the beneficial effect of VUF 8430 and histamine on nociceptive behaviour. Comparable results were obtained after intrathecal administration of drugs. The intrathecal administration of the α2-adrenoceptor agonist clonidine ameliorated mechanical and thermal allodynia in SNI mice. The clonidine-induced anti-hypersensitivity effect was prevented by intra LC pretreatment with JNJ 10191584. In addition, clonidine failed to suppress neuropathic pain in H4 deficient mice. LC H4 receptors showed a ubiquitous distribution within LC, a neuronal localization and H4 immunostaining was detected on noradrenergic neurons expressing phosphorylated cAMP response element-binding protein (CREB), a marker of neuronal activation. Under pain pathological conditions H4 stimulation might promote the activation of the coeruleospinal noradrenergic neurons that exert an inhibitory control over spinal dorsal horn neuronal excitability. Thus, histamine H4 receptor stimulation may represent a perspective for neuropathic pain management.

Phase I study of TAS-115, a novel oral multi-kinase inhibitor, in patients with advanced solid tumors.

TAS-115 is a novel MET, VEGFR, FMS and PDGFR inhibitor, developed to improve the continuity of drug administration with a relatively short half-life. We assessed its tolerability, safety, pharmacokinetics, efficacy, and pharmacodynamics in patients with solid tumors. This open-label, dose-escalation phase I study of TAS-115 consisted of three parts: part 1 (TAS-115 was administered orally once daily [SID]); part 2 and an expansion part (SID in a 5 days on/2 days off [5-on/2-off] schedule for 21 days per cycle). In part 1 (200-800 mg SID administered to 21 patients), systemic exposure after single administration increased almost dose-proportionally. Three dose-limiting toxicities (DLTs) were observed in three patients: grade 3 rash (650 mg), thrombocytopenia with bleeding, and rash (800 mg). The maximum tolerated dose (MTD) was determined as 650 mg SID. In part 2, the 5-on/2-off schedule was evaluated at the MTD to improve treatment exposure. No DLTs were observed and no patients required treatment interruption in cycle 1. During part 2 and the expansion part (N = 61), grade ≥3 treatment-related adverse events were reported in 47 patients, with neutropenia (24.6%), hypophosphatemia (21.3%), anemia, and thrombocytopenia (14.8% each), and leukocytopenia (11.5%) occurring in ≥10% of patients. The best overall response was stable disease in 31 of 82 patients (37.8%). An apparent reduction in fluorodesoxyglucose-uptake and bone scan index was observed in some patients. TAS-115 was generally well tolerated, with manageable toxicities and recommended phase II dose was estimated as 650 mg SID, 5-on/2-off. Furthermore, promising antitumor activity was observed.

Evaluation of thioamides, thiolactams and thioureas as hydrogen sulfide (H2S) donors for lowering blood pressure.

Hydrogen sulfide (H2S) is a biologically important gaseous molecule that exhibits promising protective effects against a variety of pathological processes. For example, it was recognized as a blood pressure lowering agent. Aligned with the need for easily modifiable platforms for the H2S supply, we report here the preparation and the H2S release kinetics from a series of structurally diversified thioamides, thiolactams and thioureas. Three different thionation methods based on the usage of a phosphorus pentasulfide and Lawesson reagent were applied to prepare the target thioamides and thiolactams. Furthermore, obtained H2S donors were evaluated both in in vivo and in vitro studies. The kinetic parameters of the liberating H2S was determined and compared with NaHS and GYY4137 using two different detection technics i.e.; fluorescence labeling 7-azido-4-methyl-2H-chromen-2-one and 5,5'-dithiobis (2-nitrobenzoic acid), sulfhydryl probe, also known as the Ellman's reagent. We have proved that the amount of releasing H2S from these compounds is controllable through structural modifications. Finally, the present study shows a hypotensive response to an intravenous administration of the developed donors in the anesthetized rats.

Reactive Oxygen Species Play a Biphasic Role in Brain Ischemia.

OBJECTIVE: Reactive oxygen species (ROS) are the essential mechanism involving in the ischemic process. Due to their complex characteristics, the precise effects of ROS on post-ischemic neurons remain uncertain. This study aimed to investigate the potential role of ROS in brain ischemia. METHODS: Dynamic ROS levels in the perifocal cortex were evaluated after right middle cerebral artery occlusion (MCAO) of SD rats. Furthermore the role of ROS was assessed following delayed treatment with the ROS scavenger dimethylthiourea (DMTU) after brain ischemia. RESULTS: ROS levels markedly increased at 1 hr after reperfusion and then gradually decreased as the post-reperfusion time interval increased. ROS levels reached their lowest point at 3 days after reperfusion before increasing and showing a second peak at 7 days after reperfusion. ROS levels negatively correlated with neurological function scores. Delayed DMTU treatment after stroke worsened neurological outcomes, decreased microvessel density and inhibited stress-activated protein kinase activation. CONCLUSION: ROS may play a biphasic role in cerebral ischemia. Namely, ROS may induce damage during the injury phase of brain ischemia and participate in improving neurological function during the recovery phase.

Intracerebellar microinjection of histaminergic compounds on locomotor and exploratory behaviors in mice.

The neural histaminergic system innervates the cerebellum, with a high density of fibers in the vermis and flocculus. The cerebellum participates in motor functions, but the role of the histaminergic system in this function is unclear. In the present study, we investigated the effects of intracerebellar histamine injections and H1, H2 and H3 receptor antagonist injections (chlorpheniramine, ranitidine, and thioperamide, respectively) and H4 receptor agonist (VUF-8430) on locomotor and exploratory behaviors in mice. The cerebellar vermis of male mice was implanted with guide cannula. After three days of recovery,the animals received microinjections of saline or histamine (experiment1), saline or chlorpheniramine (experiment 2), saline or ranitidine(experiment 3), saline or thioperamide (experiment 4), and saline or VUF-8430 (experiment 5) in different concentrations. Five minutes postinjection,the open field test was performed. The data were analyzed using one-way ANOVA and Duncan's post hoc test. The microinjections of histamine, ranitidine or thioperamide did not lead any behavioral effects at the used doses. In contrast, animals that received chlorpheniramine at the highest dose (0.16 nmol) and VUF-8430 at the highest dose (1.48 nmol)were more active in the open field apparatus, with an increase in the number of crossed quadrants, number of rearings and time spent in the central area of the arena, suggesting that chlorpheniramine and VUF-8430 modulates locomotor and exploratory behaviors in mice.

Hedgehog pathway inhibitors of the acylthiourea and acylguanidine class show antitumor activity on colon cancer in vitro and in vivo.

Small series of acylguanidine and acylthiourea derivatives were synthesized in gram-scale and assayed for their ability to modulate the Hh signalling pathway. In vitro studies showed a low micromolar inhibitory activity toward tumor cell lines, while the oral administration revealed an excellent ADME profile in vivo. Compound 5 emerged as the most active and safe inhibitor of colon cancer cells both in vitro and in a xenograft mouse model. Based on these data, 5 could be prioritized to further development with the perspective of clinical studies.

Determination of optimal dose of allylthiourea (ATU) for the batch respirometric test of activated sludge.

Allylthiourea is a known specific inhibitor for ammonium oxidiser to suppress its oxygen uptake, and is commonly used for various kinds of batch respirometric tests to detect heterotrophic respiration in activated sludge. However, when high heterotrophs were present in the sample, it appeared the inhibitor was noticeably degraded and reached below the inhibition threshold after a couple of days, which resulted in overestimation of the heterotrophic respiration. The biological decomposition of the inhibitor was expressed with a Monod-type rate expression having a half-saturation coefficient of 980 mg-COD/L and maximum specific growth rate of 1.0 d-1. The developed kinetic model, including the growth and decay of the heterotrophs and nitrifiers, indicated that the ATU with about 90 mg-ATU/L which was initially dosed to the system would reach below the inhibition threshold of 1.0 mg-ATU/L after 10 days when 750 mg-COD/L of heterotrophs were present. From the kinetic model, an empirical formula to calculate a safe minimum ATU dose for the batch respirometric test was elaborated. The model also provided a modified experimental procedure to accurately estimate the initial heterotrophic biomass concentration in the sample and its specific decay rate based on IWA Activated Sludge Models.

Salubrinal and robenacoxib treatment after global cerebral ischemia. Exploring the interactions between ER stress and inflammation.

BACKGROUND: Blood reperfusion of the ischemic tissue after stroke promotes increases in the inflammatory response as well as accumulation of unfolded/misfolded proteins in the cell, leading to endoplasmic reticulum (ER) stress. Both Inflammation and ER stress are critical processes in the delayed death of the cells damaged after ischemia. The aim of this study is to check the putative synergic neuroprotective effect by combining anti-inflammatory and anti-ER stress agents after ischemia. METHODS: The study was performed on a two-vessel occlusion global cerebral ischemia model. Animals were treated with salubrinal one hour after ischemia and with robenacoxib at 8 h and 32 h after ischemia. Parameters related to the integrity of the blood-brain barrier (BBB), such as matrix metalloproteinase 9 and different cell adhesion molecules (CAMs), were analyzed by qPCR at 24 h and 48 h after ischemia. Microglia and cell components of the neurovascular unit, including neurons, endothelial cells and astrocytes, were analyzed by immunofluorescence after 48 h and seven days of reperfusion. RESULTS: Pharmacologic control of ER stress by salubrinal treatment after ischemia, revealed a neuroprotective effect over neurons that reduces the transcription of molecules involved in the impairment of the BBB. Robenacoxib treatment stepped neuronal demise forward, revealing a detrimental effect of this anti-inflammatory agent. Combined treatment with robenacoxib and salubrinal after ischemia prevented neuronal loss and changes in components of the neurovascular unit and microglia observed when animals were treated only with robenacoxib. CONCLUSION: Combined treatment with anti-ER stress and anti-inflammatory agents is able to provide enhanced neuroprotective effects reducing glial activation, which opens new avenues in therapies against stroke.

Salubrinal protects human skin fibroblasts against UVB-induced cell death by blocking endoplasmic reticulum (ER) stress and regulating calcium homeostasis.

The role of UVB in skin photo damages has been widely reported. Overexposure to UVB will induce severe DNA damages in epidermal cells and cause most cytotoxic symptoms. In the present study, we tested the potential activity of salubrinal, a selective inhibitor of Eukaryotic Initiation Factor 2 (eIF2) -alpha phosphatase, against UV-induced skin cell damages. We first exposed human fibroblasts to UVB radiation and evaluated the cytosolic Ca2+ level as well as the induction of ER stress. We found that UVB radiation induced the depletion of ER Ca2+ and increased the expression of ER stress marker including phosphorylated PERK, CHOP, and phosphorylated IRE1α. We then determined the effects of salubrinal in skin cell death induced by UVB radiation. We observed that cells pre-treated with salubrinal had a higher survival rate compared to cells treated with UVB alone. Pre-treatment with salubrinal successfully re-established the ER function and Ca2+ homeostasis. Our results suggest that salubrinal can be a potential therapeutic agents used in preventing photoaging and photo damages.

A novel serine racemase inhibitor suppresses neuronal over-activation in vivo.

Serine racemase (SRR) is an enzyme that produces d-serine from l-serine. d-Serine acts as an endogenous coagonist of NMDA-type glutamate receptors (NMDARs), which regulate many physiological functions. Over-activation of NMDARs induces excitotoxicity, which is observed in many neurodegenerative disorders and epilepsy states. In our previous works on the generation of SRR gene knockout (Srr-KO) mice and its protective effects against NMDA- and Aß peptide-induced neurodegeneration, we hypothesized that the regulation of NMDARs' over-activation by inhibition of SRR activity is one such therapeutic strategy to combat these disease states. In the previous study, we performed in silico screening to identify four compounds with inhibitory activities against recombinant SRR. Here, we synthesized 21 derivatives of candidate 1, one of four hit compounds, and performed screening by in vitro evaluations. The derivative 13J showed a significantly lower IC50 value in vitro, and suppressed neuronal over-activation in vivo.

Histamine H4 receptor agonist-induced relief from painful peripheral neuropathy is mediated by inhibition of spinal neuroinflammation and oxidative stress.

BACKGROUND AND PURPOSE: Neuropathic pain is under-treated, with a detrimental effect on quality of life, partly because of low treatment efficacy, but also because pathophysiological mechanisms are not fully elucidated. To clarify the pathobiology of neuropathic pain, we studied the contribution of neuroinflammation and oxidative stress in a model of peripheral neuropathy. We also assessed an innovative treatment for neuropathic pain by investigating the effects of histamine H4 receptor ligands in this model. EXPERIMENTAL APPROACH: A peripheral mononeuropathy was induced in mice, by spared nerve injury (SNI). Neuroinflammation and oxidative stress parameters were evaluated by spectrophotometry. The mechanical (von Frey test) and thermal (plantar test) nociceptive thresholds were evaluated. KEY RESULTS: SNI mice showed increased expression of the pro-inflammatory cytokines IL-1ß and TNF-α, decreased antioxidant enzyme Mn-containing SOD (MnSOD), increased levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), an indicator of oxidative DNA damage, and of PARP, nuclear enzyme activated upon DNA damage. Intrathecal administration of VUF 8430 (H4 receptor agonist) reversed the mechanical and thermal allodynia and was associated with decreased expression of IL-1ß, TNF-α, 8-OHdG and PARP and with restoration of MnSOD activity in the spinal cord and sciatic nerve. These effects were prevented by JNJ 10191584 (H4 receptor antagonist). CONCLUSION AND IMPLICATIONS: In the SNI mouse model of neuropathic pain, neuronal H4 receptor stimulation counteracts hyperalgesia and reduces neuroinflammation and oxidative stress in the spinal cord and sciatic nerve. Targeting both oxidative stress and pro-neuroinflammatory pathways through H4 receptor-mediated mechanisms could have promising therapeutic potential for neuropathic pain management.

Cytotoxicity of 11-epi-Sinulariolide Acetate Isolated from Cultured Soft Corals on HA22T Cells through the Endoplasmic Reticulum Stress Pathway and Mitochondrial Dysfunction.

Natural compounds from soft corals have been increasingly used for their antitumor therapeutic properties. This study examined 11-epi-sinulariolide acetate (11-epi-SA), an active compound isolated from the cultured soft coral Sinularia flexibilis, to determine its potential antitumor effect on four hepatocellular carcinoma cell lines. Cell viability was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and the results demonstrated that 11-epi-SA treatment showed more cytotoxic effect toward HA22T cells. Protein profiling of the 11-epi-SA-treated HA22T cells revealed substantial protein alterations associated with stress response and protein synthesis and folding, suggesting that the mitochondria and endoplasmic reticulum (ER) play roles in 11-epi-SA-initiated apoptosis. Moreover, 11-epi-SA activated caspase-dependent apoptotic cell death, suggesting that mitochondria-related apoptosis genes were involved in programmed cell death. The unfolded protein response signaling pathway-related proteins were also activated on 11-epi-SA treatment, and these changes were accompanied by the upregulated expression of growth arrest and DNA damage-inducible protein (GADD153) and CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP), the genes encoding transcription factors associated with growth arrest and apoptosis under prolonged ER stress. Two inhibitors, namely salubrinal (Sal) and SP600125, partially abrogated 11-epi-SA-related cell death, implying that the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK)-activating transcription factor (ATF) 6-CHOP or the inositol-requiring enzyme 1 alpha (IRE1α)-c-Jun N-terminal kinase (JNK)-cJun signal pathway was activated after 11-epi-SA treatment. In general, these results suggest that 11-epi-SA exerts cytotoxic effects on HA22T cells through mitochondrial dysfunction and ER stress cell death pathways.