Receptor-independent Effects Research Articles

Effects of a Serotonergic Psychedelic on the Lipid Bilayer.

Serotonergic psychedelics, known for their hallucinogenic effects, have attracted interest due to their ability to enhance neuronal plasticity and potential therapeutic benefits. Although psychedelic-enhanced neuroplasticity is believed to require activation of 5-hydroxytryptamine (serotonin) 2A receptors (5-HT2ARs), serotonin itself is less effective in promoting such plasticity. Also, the psychoplastogenic effects of these molecules correlate with their lipophilicity, leading to suggestions that they act by influencing the intracellular receptors. However, their lipophilicity also implies that a significant quantity of lipids is accumulated in the lipid bilayer, potentially altering the physical properties of the membrane. Here, we probe whether the serotonergic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) can affect the properties of artificial lipid bilayers and if that can potentially affect processes such as membrane fusion. Solid-state NMR spectroscopy shows that the DOI strongly induces disorder in the lipid acyl chains. Atomic force microscopy shows that it can shrink the ordered domains in a biphasic lipid bilayer and can reduce the force needed to form nanopores in the membrane. Fluorescence correlation spectroscopy shows that DOI can promote vesicle association, and total internal fluorescence microscopy shows that it enhances vesicle fusion to a supported lipid bilayer. While serotonin has also recently been shown to cause similar effects, DOI is more than two orders of magnitude more potent in evoking these. Our results suggest that the receptor-independent effects of serotonergic psychedelics on lipid membranes may contribute to their biological actions, especially those that require significant membrane remodeling, such as neuronal plasticity.

The Acute Inflammatory Potential of Particles From the Echinococcus granulosus Laminated Layer Is Moderated by Its Calcium Inositol Hexakisphosphate Component.

Cystic echinococcosis is caused by the tissue-dwelling larva (hydatid) of Echinococcus granulosus sensu lato. A salient feature is that this larva is protected by the acellular laminated layer (LL). As the parasite grows, the LL sheds abundant particles that can accumulate in the parasite's vicinity. The potential of LL particles to induce inflammation in vivo has not been specifically analysed. It is not known how each of its two major components, namely highly glycosylated mucins and calcium inositol hexakisphosphate (InsP6) deposits, impacts inflammation induced by the LL as a whole. In this work, we show that LL particles injected intraperitoneally cause infiltration of eosinophils, neutrophils and monocytes/macrophages as well as the disappearance of resident (large peritoneal) macrophages. Strikingly, the absence of calcium InsP6 enhanced the recruitment of all the inflammatory cell types analysed. In contrast, oxidation of the mucin carbohydrates caused decreased recruitment of neutrophils. The carbohydrate-oxidised particles caused cell influx nonetheless, which may be explained by possible receptor-independent effects of LL particles on innate immune cells, as suggested by previous works from our group. In summary, LL particles can induce acute inflammatory cell recruitment partly dependent on its mucin glycans, and this recruitment is attenuated by the calcium InsP6 component.

Prostaglandin 15d-PGJ2 inhibits proliferation of lung adenocarcinoma cells by inducing ROS production and activation of apoptosis via sirtuin-1

Lung adenocarcinoma (LUADC) belongs to the most prevalent and lethal cancer types. As 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) displays anti-oxidative, -inflammatory, and -cancer properties, we investigated whether this cyclopentenone PG, a stable degradation end-product of cyclooxygenase-generated PGD2, exerts beneficial effects in three LUADC cell lines (A549, H1299, H23). We here report that 15d-PGJ2 had substantial cytotoxic effects in all three LUADC cell lines by promoting early apoptosis and inhibiting the cell cycle, proliferation, and migration. As indicators of cell malignancy, scratch closure and colony formation were significantly inhibited by 15d-PGJ2. 15d-PGJ2 induced generation of ROS and subsequent activation of MAPKs. Expression of Nrf-2, a well-known tumor driver, was markedly diminished by 15d-PGJ2 treatment. Although PPARγ, DP1, and DP2 are expressed in LUADC cells, blocking these receptors with specific inhibitors (SR16832 and BW245C) did not reverse 15d-PGJ2-mediated cytotoxicity, suggesting receptor-independent effects. 15d-PGJ2 decreased SIRT1 expression in LUADC cells and the knockdown of SIRT1 diminished the cytotoxic effects of 15d-PGJ2. Importantly, 15d-PGJ2 significantly reduced tumor growth using the chorioallantoic membrane (CAM) assay. The structural analog of 15d- PGJ2, 9,10-dihydro-15d-PGJ2 (lacking the α,β-unsaturated ketone structural element), did not show any toxic effects in LUADC cells. Altogether, our findings suggest that 15d-PGJ2 led to significantly reduced tumor growth and cell proliferation in three LUADC cell lines. The CAM assay results suggest that 15d-PGJ2 is a suitable endogenous compound to interfere with LUADC tumor progression. We show that SIRT1 modulates the effects of 15d-PGJ2 and may be used as a therapeutic target for LUADC.

Off-target activity of NBOMes and NBOMe analogs at the µ opioid receptor.

New psychoactive substances (NPS) are introduced on the illicit drug market at a rapid pace. Their molecular targets are often inadequately elucidated, which contributes to the delayed characterization of their pharmacological effects. Inspired by earlier findings, this study set out to investigate the µ opioid receptor (MOR) activation potential of a large set of psychedelics, substances which typically activate the serotonin (5-HT2A) receptor as their target receptor. We observed that some substances carrying the N-benzyl phenethylamine (NBOMe) structure activated MOR, as confirmed by both the NanoBiT® βarr2 recruitment assay and the G protein-based AequoScreen® Ca2+ release assay. The use of two orthogonal systems proved beneficial as some aspecific, receptor independent effects were found for various analogs when using the Ca2+ release assay. The specific 'off-target' effects at MOR could be blocked by the opioid antagonist naloxone, suggesting that these NBOMes occupy the same common opioid binding pocket as conventional opioids. This was corroborated by molecular docking, which revealed the plausibility of multiple interactions of 25I-NBOMe with MOR, similar to those observed for opioids. Additionally, structure-activity relationship findings seen in vitro were rationalized in silico for two 25I-NBOMe isomers. Overall, as MOR activity of these psychedelics was only noticed at high concentrations, we consider it unlikely that for the tested compounds there will be a relevant opioid toxicity in vivo at physiologically relevant concentrations. However, small modifications to the original NBOMe structure may result in a panel of more efficacious and potent MOR agonists, potentially exhibiting a dual MOR/5-HT2A activation potential.

Melatonin as a Potential Approach to Anxiety Treatment.

Anxiety disorders are the most common mental diseases. Anxiety and the associated physical symptoms may disturb social and occupational life and increase the risk of somatic diseases. The pathophysiology of anxiety development is complex and involves alterations in stress hormone production, neurosignaling pathways or free radical production. The various manifestations of anxiety, its complex pathophysiological background and the side effects of available treatments underlie the quest for constantly seeking therapies for these conditions. Melatonin, an indolamine produced in the pineal gland and released into the blood on a nightly basis, has been demonstrated to exert anxiolytic action in animal experiments and different clinical conditions. This hormone influences a number of physiological actions either via specific melatonin receptors or by receptor-independent pleiotropic effects. The underlying pathomechanism of melatonin's benefit in anxiety may reside in its sympatholytic action, interaction with the renin-angiotensin and glucocorticoid systems, modulation of interneuronal signaling and its extraordinary antioxidant and radical scavenging nature. Of importance, the concentration of this indolamine is significantly higher in cerebrospinal fluid than in the blood. Thus, ensuring sufficient melatonin production by reducing light pollution, which suppresses melatonin levels, may represent an endogenous neuroprotective and anxiolytic treatment. Since melatonin is freely available, economically undemanding and has limited side effects, it may be considered an additional or alternative treatment for various conditions associated with anxiety.

Intercommunication between Voltage-Gated Calcium Channels and Estrogen Receptor/Estrogen Signaling: Insights into Physiological and Pathological Conditions

Voltage-gated calcium channels (VGCCs) and estrogen receptors are important cellular proteins that have been shown to interact with each other across varied cells and tissues. Estrogen hormone, the ligand for estrogen receptors, can also exert its effects independent of estrogen receptors that collectively constitute non-genomic mechanisms. Here, we provide insights into the VGCC regulation by estrogen and the possible mechanisms involved therein across several cell types. Notably, most of the interaction is described in neuronal and cardiovascular tissues given the importance of VGCCs in these electrically excitable tissues. We describe the modulation of various VGCCs by estrogen known so far in physiological conditions and pathological conditions. We observed that in most in vitro studies higher concentrations of estrogen were used while a handful of in vivo studies used meager concentrations resulting in inhibition or upregulation of VGCCs, respectively. There is a need for more relevant physiological assays to study the regulation of VGCCs by estrogen. Additionally, other interacting receptors and partners need to be identified that may be involved in exerting estrogen receptor-independent effects of estrogen.

Off-target activity of NBOMes and NBOMe analogs at the μ opioid receptor

New psychoactive substances (NPS) are introduced on the illicit drug market at a rapid pace. They are usually poorly pharmacologically characterized, leaving users unaware of the potential harms they could be exposed to. Apart from the unknown effects and potencies of these new substances, their exact molecular targets are often inadequately elucidated. Guided by recent literature, we investigated the μ opioid receptor (MOR) activation potential of a large set of psychedelics, which typically activate their target receptor, the serotonin (5-HT2A) receptor. Screening for MOR activity of a panel of psychedelics was done using a cell-based NanoBiT® bioassay. The NanoBiT® assay monitors the recruitment of the intracellular signaling protein β-arrestin2 to the ligand activated MOR receptor. The principle exploits functional complementation of a split nanoluciferase enzyme of which the inactive subunits are either fused to the receptor and βarr2. Receptor activation causes the 2 subunits to come in close proximity, resulting in restoration of the nanoluciferase activity. Upon addition of the substrate, a luminescent signal can be detected using a luminometer. Based on the results of this initial screening, MOR activity of a selected panel of NBOMes and NBOMe analogs was evaluated using the both the NanoBiT® and AequoScreen® assay, the latter measuring the rapid intracellular calcium flux caused by receptor activation, a more downstream effect caused by G protein signaling. Using the NanoBiT® assay, 5 NBOMes showed MOR activation potential. Based on these findings, a panel of NBOMe analogs was selected and evaluated using 2 distinct assays. Comparing both assays, the same overall trends regarding MOR activity could be determined. The iodo analog 25I-NBOMe was more potent than the bromo substituted 25B-NBOMe, which was more potent than the chloro analog 25C-NBOMe, signifying that MOR activity increased with an increased size of the halogen atom. Similarly, MOR activity increased with increasing size of the alkyl side chain, with the ethylated 25E-NBOMe being more active than the methylated 25D-NBOMe. However, a propyl or isopropyl side chain might be too long or bulky, as the 25P-NBOMe and 25iP-NBOMe showed a substantial decrease in activity. NBOMe compounds were more active at MOR than their NBOH counterparts, whereas earlier data showed that they had a similar activity at their designated target receptor 5-HT2A. Moving the methoxy group from position 2 to position 3 or 4 resulted in an important decrease in MOR activity. Furthermore, the effects at MOR of the analyzed compounds could be blocked by the opioid antagonist naloxone, suggesting that these NBOMes occupy the same common opioid binding pocket as conventional opioids. Using the AequoScreen® assay, aspecific, receptor independent effects were found for the alkylated 25iP-NBOMe, 25E-NBOMe and 25D-NBOMe, indicating that these may directly interact with other targets in the downstream signaling pathway. A limited potential to activate the MOR was found for 10 NBOMes and NBOMe analogs, which was confirmed using 2 distinct cell-based assays. Structure-activity relationships could be determined, and additional experiments revealed that the effects of these psychedelics at MOR could be antagonized by naloxone, signifying that these substances occupy the same binding pocket as common opioids. Some compounds showed an aspecific effect in the AequoScreen® assay, which was not observed using the NanoBiT® assay. As MOR activity of these psychedelics was only noticed at high concentrations, it is unlikely that these will contribute to pronounced opioid toxicity at physiologically relevant concentrations. However, small modifications to the original NBOMe structure may result in a panel of more efficacious and potent MOR agonists.

Immunology of a unique biological structure: the Echinococcus laminated layer.

The larval stages of the cestode parasites belonging to the genus Echinococcus grow within internal organs of humans and a range of animal species. The resulting diseases, collectively termed echinococcoses, include major neglected tropical diseases of humans and livestock. Echinococcus larvae are outwardly protected by the laminated layer (LL), an acellular structure that is unique to this genus. The LL is based on a fibrillar meshwork made up of mucins, which are decorated by galactose-rich O-glycans. In addition, in the species cluster termed E. granulosus sensu lato, the LL features nano-deposits of the calcium salt of myo-inositol hexakisphosphate (Insp6). The main purpose of our article is to update the immunobiology of the LL. Major recent advances in this area are (i) the demonstration of LL "debris" at the infection site and draining lymph nodes, (ii) the characterization of the decoy activity of calcium Insp6 with respect to complement, (iii) the evidence that the LL mucin carbohydrates interact specifically with a lectin receptor expressed in Kupffer cells (Clec4F), and (iv) the characterization of what appear to be receptor-independent effects of LL particles on dendritic cells and macrophages. Much information is missing on the immunology of this intriguing structure: we discuss gaps in knowledge and propose possible avenues for research.

Pleiotropic effects of clopidogrel.

Clopidogrel is a widely prescribed prodrug with anti-thrombotic activity through irreversible inhibition of the P2Y12 receptor on platelets. It is FDA-approved for the clinical management of thrombotic diseases like unstable angina, myocardial infarction, stroke, and during percutaneous coronary interventions. Hepatic clopidogrel metabolism generates several distinct metabolites. Only one of these metabolites is responsible for inhibiting the platelet P2Y12 receptor. Importantly, various non-hemostatic effects of clopidogrel therapy have been described. These non-hemostatic effects are perhaps unsurprising, as P2Y12 receptor expression has been reported in multiple tissues, including osteoblasts, leukocytes, as well as vascular endothelium and smooth muscle. While the "inactive" metabolites have been commonly thought to be biologically inert, recent findings have uncovered P2Y12 receptor-independent effects of clopidogrel treatment that may be mediated by understudied metabolites. In this review, we summarize both the P2Y12 receptor-mediated and non-P2Y12 receptor-mediated effects of clopidogrel and its metabolites in various tissues.

Melatonin - A Cutaneous Perspective

Melatonin (MLT) is an endogenous hormone secreted from the pineal gland, located deep in the brain in the epithalamus associated with numerous biological activities. The primary function of melatonin is to regulate sleep-wake cycles. However, research over the last few years has enlightened a range of functions associated with this molecule, including anti-inflammatory, direct and indirect antioxidant activity, regenerative tissue benefits, and preservation of mitochondrial function. Melatonin’s anti-inflammatory and antioxidant support, coupled with its mitochondrial modulation, makes it a vital molecule to use for skin health homeostasis. The cutaneous melatoninergic system’s widespread expression and pleiotropic activity provides for a high level of cell-specific selectivity. Several skin cells, including normal and malignant keratinocytes, melanocytes, fibroblasts and hair follicles, express melatonin receptors. Melatonin also has receptor-independent effects that protect against oxidative stress and can reduce ultraviolet radiation-induced damage. Several functions of melatonin in the skin have been experimentally implicated such as hair growth cycling, fur pigmentation, melanoma control, suppression of ultraviolet-induced damage to the skin cell. Melatonin may play a role in treating several dermatoses e.g., atopic eczema, psoriasis, melasma, ulcer healing, and malignant melanoma. There is a plethora of functional melatonin properties, which still await to be fully appreciated by dermatologists. The current review emphasizes few of the established uses and few emerging potentialities that render melatonin a promising candidate for managing several diseases.

ATP and adenosine-Two players in the control of seizures and epilepsy development.

Despite continuous advances in understanding the underlying pathogenesis of hyperexcitable networks and lowered seizure thresholds, the treatment of epilepsy remains a clinical challenge. Over one third of patients remain resistant to current pharmacological interventions. Moreover, even when effective in suppressing seizures, current medications are merely symptomatic without significantly altering the course of the disease. Much effort is therefore invested in identifying new treatments with novel mechanisms of action, effective in drug-refractory epilepsy patients, and with the potential to modify disease progression. Compelling evidence has demonstrated that the purines, ATP and adenosine, are key mediators of the epileptogenic process. Extracellular ATP concentrations increase dramatically under pathological conditions, where it functions as a ligand at a host of purinergic receptors. ATP, however, also forms a substrate pool for the production of adenosine, via the action of an array of extracellular ATP degrading enzymes. ATP and adenosine have assumed largely opposite roles in coupling neuronal excitability to energy homeostasis in the brain. This review integrates and critically discusses novel findings regarding how ATP and adenosine control seizures and the development of epilepsy. This includes purine receptor P1 and P2-dependent mechanisms, release and reuptake mechanisms, extracellular and intracellular purine metabolism, and emerging receptor-independent effects of purines. Finally, possible purine-based therapeutic strategies for seizure suppression and disease modification are discussed.

Estrogen Receptor Modulators in Viral Infections Such as SARS-CoV-2: Therapeutic Consequences.

COVID-19 is a pandemic respiratory disease caused by the SARS−CoV−2 coronavirus. The worldwide epidemiologic data showed higher mortality in males compared to females, suggesting a hypothesis about the protective effect of estrogens against severe disease progression with the ultimate end being patient’s death. This article summarizes the current knowledge regarding the potential effect of estrogens and other modulators of estrogen receptors on COVID-19. While estrogen receptor activation shows complex effects on the patient’s organism, such as an influence on the cardiovascular/pulmonary/immune system which includes lower production of cytokines responsible for the cytokine storm, the receptor-independent effects directly inhibits viral replication. Furthermore, it inhibits the interaction of IL-6 with its receptor complex. Interestingly, in addition to natural hormones, phytestrogens and even synthetic molecules are able to interact with the estrogen receptor and exhibit some anti-COVID-19 activity. From this point of view, estrogen receptor modulators have the potential to be included in the anti-COVID-19 therapeutic arsenal.

FTY720 (Fingolimod) Ameliorates Brain Injury through Multiple Mechanisms and is a Strong Candidate for Stroke Treatment.

FTY720 (Fingolimod) is a known sphingosine-1-phosphate (S1P) receptor agonist that exerts strong anti-inflammatory effects and was approved as the first oral drug for the treatment of multiple sclerosis by the US Food and Drug Administration (FDA) in 2010. FTY720 is mainly associated with unique functional “antagonist” and “agonist” mechanisms. The functional antagonistic mechanism is mediated by the transient down-regulation and degradation of S1P receptors on lymphocytes, which prevents lymphocytes from entering the blood stream from the lymph node. This subsequently results in the development of lymphopenia and reduces lymphocytic inflammation. Functional agonistic mechanisms are executed through S1P receptors expressed on the surface of various cells including neurons, astrocytes, microglia, and blood vessel endothelial cells. These functions might play important roles in regulating anti-apoptotic systems, modulating brain immune and phagocytic activities, preserving the Blood-Brain-Barrier (BBB), and the proliferation of neural precursor cells. Recently, FTY720 have shown receptor-independent effects, including intracellular target bindings and epigenetic modulations. Many researchers have recognized the positive effects of FTY720 and launched basic and clinical experiments to test the use of this agent against stroke. Although the mechanism of FTY720 has not been fully elucidated, its efficacy against cerebral stroke is becoming clear, not only in animal models, but also in ischemic stroke patients through clinical trials. In this article, we review the data obtained from laboratory findings and preliminary clinical trials using FTY720 for stroke treatment.

Aldosterone Stimulates Its Biosynthesis Via a Novel GPER-Mediated Mechanism.

The G protein-coupled estrogen receptor (GPER) mediates an aldosterone secretagogue effect of 17β-estradiol in human HAC15 adrenocortical cells after estrogen receptor β blockade. Because GPER mediates mineralocorticoid receptor-independent aldosterone effects in other cell types, we hypothesized that aldosterone could modulate its own synthesis via GPER activation. HAC15 cells were exposed to aldosterone in the presence or absence of canrenone, a mineralocorticoid receptor antagonist, and/or of the selective GPER antagonist G36. Aldosterone synthase (CYP11B2) mRNA and protein levels changes were the study end points. Similar experiments were repeated in strips obtained ex vivo from aldosterone-producing adenoma (APA) and in GPER-silenced HAC15 cells. Aldosterone markedly increased CYP11B2 mRNA and protein expression (vs untreated samples, P < 0.001) in both models by acting via GPER, because these effects were abolished by G36 (P < 0.01) and not by canrenone. GPER-silencing (P < 0.01) abolished the aldosterone-induced increase of CYP11B2, thus proving that aldosterone acts via GPER to augment the step-limiting mitochondrial enzyme (CYP11B2) of its synthesis. Angiotensin II potentiated the GPER-mediated effect of aldosterone on CYP11B2. Coimmunoprecipitation studies provided evidence for GPER-angiotensin type-1 receptor heterodimerization. We propose that this autocrine-paracrine mechanism could enhance aldosterone biosynthesis under conditions of immediate physiological need in which the renin-angiotensin-aldosterone system is stimulated as, for example, hypovolemia. Moreover, as APA overexpresses GPER this mechanism could contribute to the aldosterone excess that occurs in primary aldosteronism in a seemingly autonomous fashion from angiotensin II.

Soy-Derived Phytochemical Genistein Modifies Chromatome Topology to Restrict Cancer Cell Proliferation.

Epidemiological data indicate that human cancer risk is significantly reduced by the consumption of soy-based foods containing the "phytoestrogen" genistein, which can signal via host cell estrogen receptors. While additional chemoprotective effects of genistein induced by epigenetic factors have also been reported, the key molecules and mechanisms involved are poorly defined. We therefore investigated genistein effects on chromatin-bound proteins in the estrogen receptor-deficient cell line MDA-MB-231 which is insensitive to phytoestrogen signaling. After exposure to low-dose genistein for >1 month, MDA-MB-231 cells exhibited stable epigenetic alterations that are analyzed via partial MNase digestion and TMT-based quantitative proteomics. 3177 chromatin-bound proteins are identified with high confidence, including 882 molecules that displayed altered binding topology after cell conditioning with genistein. Prolonged phytochemical exposure conferred heritable changes in the binding topology of key epigenetic regulators including ATRX, SUV39H1/H2, and HP1BP3 that are preserved in untreated progeny, resulting in sustained downregulation of proliferation genes and reduced cell growth. These data indicate that soy derivative genistein exerts complex estrogen receptor-independent effects on the epigenome likely to influence tumorigenesis by restricting cell growth.

The Inside Story of Adenosine.

Several physiological functions of adenosine (Ado) appear to be mediated by four G protein-coupled Ado receptors. Ado is produced extracellularly from the catabolism of the excreted ATP, or intracellularly from AMP, and then released through its transporter. High level of intracellular Ado occurs only at low energy charge, as an intermediate of ATP breakdown, leading to hypoxanthine production. AMP, the direct precursor of Ado, is now considered as an important stress signal inside cell triggering metabolic regulation through activation of a specific AMP-dependent protein kinase. Intracellular Ado produced from AMP by allosterically regulated nucleotidases can be regarded as a stress signal as well. To study the receptor-independent effects of Ado, several experimental approaches have been proposed, such as inhibition or silencing of key enzymes of Ado metabolism, knockdown of Ado receptors in animals, the use of antagonists, or cell treatment with deoxyadenosine, which is substrate of the enzymes acting on Ado, but is unable to interact with Ado receptors. In this way, it was demonstrated that, among other functions, intracellular Ado modulates angiogenesis by regulating promoter methylation, induces hypothermia, promotes apoptosis in sympathetic neurons, and, in the case of oxygen and glucose deprivation, exerts a cytoprotective effect by replenishing the ATP pool.

The Sphingosine 1-Phosphate Signaling Pathway in Epilepsy: A Possible Role for the Immunomodulator Drug Fingolimod in Epilepsy Treatment.

It is currently known that erythrocytes are the major source of sphingosine 1-phosphate (S1P) in the body. S1P acts both extracellularly as a cellular mediator and intracellularly as an important second messenger molecule. Its effects are mediated by interaction with five specific types of G proteincoupled S1P receptor. Fingolimod, is a recognized modulator of S1P receptors, and is the first orally active disease-modifying therapy that has been approved for the treatment of multiple sclerosis. Magnetic resonance imaging data suggest that fingolimod may be effective in multiple sclerosis by preventing blood-brain barrier disruption and brain atrophy. Fingolimod might also possess S1P receptorindependent effects and exerts both anti-inflammatory and neuroprotective effects. In the therapeutic management of epilepsy, there are a great number of antiepileptic drugs, but there is still a need for others that are more effective and safer. S1P and its receptors might represent a suitable novel target also in light of their involvement in neuroinflammation, a well-known process underlying seizures and epileptogenesis. The objective of this manuscript is to review the biological role of S1P and its receptors, focusing on their expression, effects and possible involvement in epilepsy; furthermore, we summarize the possible anti-seizure properties of fingolimod and discuss its possible usefulness in epilepsy treatment. We conclude that fingolimod, being already commercially available, might be easily tested for its possible therapeutic effectiveness in epileptic patients, both after a more comprehensive evaluation of the real potential of this drug and following a clear evaluation of the potential role of its main targets, including the S1P signaling pathway in epilepsy.

Pharmacological approach for drug repositioning against cardiorenal diseases.

New applications of approved clinically used drugs are being discovered. Drug repositioning is a proposed strategy for developing these drugs as therapeutic agents for different diseases. Currently, approximately 2000 drugs are used in Japan. However, the compound targets and pathways involved in the pharmacological actions of 70-80% of these drugs have not been adequately clarified. Pharmacological examination of approved drugs is an important task in drug repositioning and vital for improving drug development efficiency. This review reports that angiotensin II type 1 receptor blockers show receptor-independent effects against reactive oxygen species generation in renal cells. Additionally, nitrosonifedipine has an antioxidative effect and protects endothelial cells against oxidative stress, and pioglitazone has multiple effects that improve dysfunctions in vascular control regulated by adrenergic and calcitonin gene-related peptide-containing nerves in animal models of diabetes. These data suggest that some approved drugs could be useful for treating cardiorenal diseases. Since cardiorenal diseases are likely to have chronic pathological conditions and require chronic drug administration, highly safe drugs are needed. Compared to newly developed drugs, drug repositioning of approved drugs with safety information is considered a particularly useful technique for searching new treatments for cardiorenal diseases. J. Med. Invest. 64: 197-201, August, 2017.

Melatonin and Respiratory Diseases: A Review.

Melatonin is an indoleamine with potent multifunctional biological and pharmacological effects, both receptor dependent and receptor-independent effects, including antioxidant, anticancer, antitumor, anti-inflammatory, anti-aging, anti-diabetic, antiviral, neuroprotective activities. Melatonin mitigates tissue injury via modification of abnormalities in redox status and other biochemical markers. At the molecular level, the biological and pharmacological activities of melatonin are attributed to the inhibition of nuclear factor-κappa beta (NF-κβ), c-Fos over expression and down-regulation of matrix metalloproteinases-3 (MMP-3), which are regulators of pro-inflammatory and pro-fibrotic cytokines. There are numerous scientific reports on the therapeutic potential of melatonin in treatment of asthma, respiratory diseases for infections, chronic obstructive pulmonary disease, lung cancer, pleural cavity diseases, as well as vascular pulmonary disease. In the present communication, we systematically review the therapeutic potential of melatonin in the treatment of respiratory diseases along with its molecular mechanism of actions.

Emerging Roles of Apolipoprotein E and Apolipoprotein A-I in the Pathogenesis and Treatment of Lung Disease.

Emerging roles are being recognized increasingly for apolipoproteins in the pathogenesis and treatment of lung diseases on the basis of their ability to suppress inflammation, oxidative stress, and tissue remodeling, and to promote adaptive immunity and host defense. Apolipoproteins, such as apolipoprotein E (apoE) and apolipoprotein A-I (apoA-I), are important components of lipoprotein particles that facilitate the transport of cholesterol, triglycerides, and phospholipids between plasma and cells. ApoE-containing lipoprotein particles are internalized into cells by low-density lipoprotein receptors (LDLRs), whereas apoA-I can interact with the ATP-binding cassette subfamily A member 1 (ABCA1) transporter to efflux cholesterol and phospholipids out of cells. ApoE and apoA-I also mediate receptor-independent effects, such as binding to and neutralizing LPS. Both apoE and apoA-I are expressed by lung cells, which allows apoE/LDLR- and apoA-I/ABCA1-dependent pathways to modulate normal lung health and the pathogenesis of respiratory diseases, including asthma, acute lung injury, cancer, emphysema, pulmonary fibrosis, and pulmonary hypertension. Data from human studies and research using experimental murine model systems have shown that both apoE and apoA-I pathways play primarily protective roles in lung biology and respiratory disease. Furthermore, apolipoprotein mimetic peptides, corresponding to the LDLR-binding domain of apoE or the class A amphipathic α-helical structure of apoA-I, have antiinflammatory and antioxidant effects that attenuate the severity of lung disease in murine models. Thus, the development of inhaled apolipoprotein mimetic peptides as a novel treatment paradigm could represent a significant advance for patients with respiratory disease who do not respond to current therapies.