P2X7-Receptor Pathway Involvement in the Anti-Inflammatory Activity of Medicinal Plants

Medicinal plants used in European folk medicine attached to Lamiales, Gentianales or Asterales orders are used to treat inflammatory disorders. Many targets have been identified but to date, implication of purinergic receptor P2X7 activation has not yet been investigated. We managed to evaluate the protective effect on P2X7 activation by plant extracts used as anti-inflammatory in European folk medicine by the YO-PRO-1 uptake dye in vitro bioassay. Results revealed that among our selected plants, species from Scrophularia and Plantago genus were able to decrease significantly P2X7 activation (>50 % at 0.1 and 1 μg/mL). UPLC/MS, dereplication and metabolomic analysis of Scrophularia extracts, allowed us to identify the cinnamoyl-iridoid harpagoside as putative inhibitor of P2X7 activation. These results open a new research field regarding the anti-inflammatory mechanism of cinnamoyl-iridoids bearing plants, which may involve the P2X7 receptor.

Is quantitative sensory testing helpful in the management of oxaliplatin neuropathy? a two-year clinical study

PURPOSE

To better understand how quantitative sensory testing could help the clinician in the management of oxaliplatin-induced peripheral neuropathy in terms of earlier and more reliable detection, we conducted a two-year prospective study.

METHODS

Thermal sensory assessment, tactile sensory assessment, neuropathic pain assessment and adverse events gradation (NCI-CTC) were performed during treatment and 6 months after treatment completion.

RESULTS

35 patients were enrolled and followed-up during one year. Cold and Warm Detection Thresholds were higher 6 months after treatment completion than at enrollment. Mechanical detection thresholds didn't change significantly. Neurotoxicity was mostly grade-1, only 18% grade-2 and no grade-3. Grade-2 patients received lower oxaliplatin cumulative dose than grade-1, which reveals effective dose adaptation and grade-2 patients were more likely to develop painful neuropathy.

CONCLUSION

Thermal thresholds impairment emerges too late to help the clinician in the prophylaxis of neuropathy. Management of OXA-treatment based on NCI-CTC, as currently recommended, remains the best way to detect neuropathy and ensure treatment adaptation.

AβPP-induced UPR Transcriptomic Signature of Glial Cells to Oxidative Stress as an Adaptive Mechanism to Preserve Cell Function and Survival

Background:

Alzheimer's disease (AD) and age-related macular degeneration (AMD) present similarities, particularly with respect to oxidative stress, including production of 4-Hydroxy-2- nonenal (HNE). AMD has been named the AD in the eye. The Müller cells (MC) function as a principal glia of the retina and maintain water/potassium, glutamate homeostasis and redox status. Any MC dysfunction results in retinal neurodegeneration.

Objectives:

We investigated the effects of HNE in human MC.

Results:

HNE induced an increase of the reactive oxygen species associated with mitochondrial dysfunction and apoptosis. HNE induced endoplasmic reticulum (ER) stress (upregulation of GRP78/Bip, and the proapoptotic factor, CHOP). HNE also impaired expression of genes controlling potassium homeostasis (KCNJ10), glutamate detoxification (GS), and the visual cycle (RLBP1). MC adaptive response to HNE included upregulation of amyloid-β protein precursor (AβPP). To determine the role of AβPP, we overexpressed AβPP in MC. Overexpression of AβPP induced strong antioxidant and anti-ER stress (PERK downregulation and GADD34 upregulation) responses accompanied by activation of the prosurvival branch of the unfolded protein response. It was also associated with upregulation of major genes involved in MC-controlled retinal homeostasis (KCNJ10, GS, and RLBP1) and protection against HNE-induced apoptosis. Therefore, AβPP is an ER and oxidative stress responsive molecule, and is able to stimulate the transcription of major genes involved in MC functions impaired by HNE.

Conclusion:

Our study suggests that targeting oxidative and ER stress might be a potential therapeutic strategy against glia impairment in AMD and AD, in light of the common features between the two pathologies.

Amyloid β Peptide Induces Apoptosis Through P2X7 Cell Death Receptor in Retinal Cells: Modulation by Marine Omega-3 Fatty Acid DHA and EPA

Retinal Müller glial cells have already been implicated in age-related macular degeneration (AMD). AMD is characterized by accumulation of toxic amyloid-β peptide (Aβ); the question we raise is as follows: is P2X7 receptor, known to play an important role in several degenerative diseases, involved in Aβ toxicity on Müller cells? Retinal Müller glial cells were incubated with Aβ for 48 h. Cell viability was assessed using the alamarBlue assay and cytotoxicity using the lactate dehydrogenase (LDH) release assay. P2X7 receptor expression was highlighted by immunolabeling observed on confocal microscopy and its activation was evaluated by YO-PRO-1 assay. Hoechst 33342 was used to evaluate chromatin condensation, and caspases 8 and 3 activation was assessed using AMC assays. Lipid formulation rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) used in Age-Related Eye Disease Study 2 was incubated on cells for 15 min prior to Aβ incubation. For the first time, we showed that Aβ induced caspase-independent apoptosis through P2X7 receptor activation on our retinal model. DHA and EPA are polyunsaturated fatty acids recommended in food supplement to prevent AMD. We therefore modulated Aβ cytotoxicity using a lipid formulation rich in DHA and EPA to have a better understanding of the results observed in clinical studies. We showed that fish oil rich in EPA and DHA, in combination with a potent P2X7 receptor antagonist, represents an efficient modulator of Aβ toxicity and that P2X7 could be an interesting therapeutic target to prevent AMD.

Hyperphosphataemia sensitizes renally impaired rats to the profibrotic effects of gadodiamide

BACKGROUND AND PURPOSE

Hyperphosphataemia is common in patients with nephrogenic systemic fibrosis (NSF). NSF has been linked to administration of gadolinium (Gd) chelates (GCs) and elevated serum phosphate levels accelerate the release of Gd from linear, non-ionic GCs but not macrocyclic GCs. Hence, we determined whether hyperphosphataemia is a cofactor or risk factor for NSF by investigating the role of hyperphosphataemia in renally impaired rats.

EXPERIMENTAL APPROACH

Firstly, the clinical, pathological and bioanalytical consequences of hyperphosphataemia were investigated in subtotal nephrectomized (SNx) Wistar rats following i.v. administration of the non-ionic, linear GC gadodiamide (5 × 2.5 mmol·kg(-1) ·day(-1) ). Secondly, the effects of several GCs were compared in these high-phosphate diet fed rats. Total Gd concentration in skin, femur and plasma was measured by inductively coupled plasma mass spectrometry (ICP-MS) and free Gd(3+) in plasma by liquid chromatography coupled to ICP-MS. Relaxometry was used to measure dissociated Gd in skin and bone.

KEY RESULTS

Four out of seven SNx rats fed a high-phosphate diet administered gadodiamide developed macroscopic and microscopic (fibrotic and inflammatory) skin lesions, whereas no skin lesions were observed in SNx rats treated with saline, the other GCs and free ligands or in the normal diet, gadodiamide-treated group. Unlike the other molecules, gadodiamide gradually increased the r(1) relaxivity value, consistent with its in vivo dissociation and release of soluble Gd.

CONCLUSIONS AND IMPLICATIONS

Hyperphosphataemia sensitizes renally impaired rats to the profibrotic effects of gadodiamide. Unlike the other GCs investigated, gadodiamide gradually dissociates in vivo. Our data confirm that hyperphosphataemia is a risk factor for NSF.

Relative exchangeable copper: a new highly sensitive and highly specific biomarker for Wilson's disease diagnosis

Wilson disease (WD) is an autosomal recessive inherited disorder of copper metabolism. Failure to diagnose WD can be dramatic leading to irreversible damages. The molecular genetic analysis of ATP7B gene is the reference test for diagnosis but the number of reported mutations of the ATP7B gene is on the rise. The analysis is cumbersome and requires tedious work. Other clinical and biological tests are proposed but it is often difficult to interpret some patients' results. A rapid and reliable biological test for WD diagnosis is still needed. Analytical reliability of Exchangeable copper (CuEXC) determination procedure is examined by studying the repeatability, the short term stability and stability in frozen serum. Relative exchangeable copper (REC=CuEXC/total copper%) is proposed and evaluated as a new diagnostic test and compared to classic tests used for WD diagnosis. Sixteen new Wilson disease patients were diagnosed in our institution between January 2009 and May 2011. The different biological tests used for WD diagnosis yielded lower sensitivity and specificity compared to our new biomarker, the REC. We show that REC is an excellent discriminatory tool for the diagnosis of WD offering 100% sensitivity and 100% specificity.

Human plasma copper proteins speciation by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry. Solutions for columns calibration by sulfur detection

Among the hyphenated techniques used to probe and identify metalloproteins, size exclusion chromatography coupled to inductively coupled plasma mass spectrometry (SEC-ICP-MS) has shown to have a central place. However, the calibration of SEC columns reveals to be tedious and always involves UV detection prior to ICP-MS. The presence of sulfur in 98% of proteins allows their detection by quadrupole ICP-MS, despite the isobaric interference ((16)O(16)O) on S, by monitoring (32)S(16)O at mass to charge ratio (m/z) 48. The formation of SO occurs spontaneously in the argon plasma but can be optimized by the introduction of oxygen gas into a reaction cell (RC) to achieve nM levels. In this article, sulfur detection was discussed upon instrumental conditions and S detection was then optimized by applying O(2) as a reaction gas. SO formation was used to calibrate SEC columns without UV detection. This simple SEC-ICP-MS method was used for plasma copper proteins in plasma healthy subjects (HS) and an untreated Wilson disease (WD) patient. Copper proteins identified in healthy subjects were transcuprein, ceruloplasmin (Cp) and albumin. The method led to results in good agreement with other methods of determination. Copper bound to Cp in the WD patient was lowered with regard to the HS, and the exchangeable Cu was highly increased.

Design of group IIA secreted/synovial phospholipase A(2) inhibitors: an oxadiazolone derivative suppresses chondrocyte prostaglandin E(2) secretion

Group IIA secreted/synovial phospholipase A₂ (GIIAPLA₂) is an enzyme involved in the synthesis of eicosanoids such as prostaglandin E₂ (PGE₂), the main eicosanoid contributing to pain and inflammation in rheumatic diseases. We designed, by molecular modeling, 7 novel analogs of 3-{4-[5(indol-1-yl)pentoxy]benzyl}-4H-1,2,4-oxadiazol-5-one, denoted C1, an inhibitor of the GIIAPLA₂ enzyme. We report the results of molecular dynamics studies of the complexes between these derivatives and GIIAPLA₂, along with their chemical synthesis and results from PLA₂ inhibition tests. Modeling predicted some derivatives to display greater GIIAPLA₂ affinities than did C1, and such predictions were confirmed by in vitro PLA₂ enzymatic tests. Compound C8, endowed with the most favorable energy balance, was shown experimentally to be the strongest GIIAPLA₂ inhibitor. Moreover, it displayed an anti-inflammatory activity on rabbit articular chondrocytes, as shown by its capacity to inhibit IL-1β-stimulated PGE₂ secretion in these cells. Interestingly, it did not modify the COX-1 to COX-2 ratio. C8 is therefore a potential candidate for anti-inflammatory therapy in joints.

Acute systemic inflammation induces central mitochondrial damage and mnesic deficit in adult Swiss mice

The aim of this study was to investigate how the brain is affected during systemic inflammation. For this purpose, Swiss mice were challenged with a single intraperitoneal dose of lipopolysaccharide (LPS; 250microg/mouse) to mimic aspects of systemic infection. Spatial learning in Y-maze test demonstrated a differential learning profile during the training test between control and LPS-treated mice, with an alteration in the latter group. We show that systemic LPS-induced inflammation and oxidative injury as assessed by reactive oxygen species (ROS) and nitrites/nitrates (NOx) production associated with reduced glutathione (GSH) depletion, cyclooxygenase-2 (COX-2) expression, and lipid peroxidation. LPS also induced a loss in mitochondrial integrity as shown by a significant decrease in membrane potential and impairment in mitochondrial redox activity. Thus, peripheral inflammation by producing brain inflammation and oxidative injury causes mnesic deficits. It remains to determine whether such events can induce neuronal dysfunction/degeneration and, with time, lead to cholinergic deficiency, amyloid deposits and cognitive impairments as they occur in Alzheimer's disease.

Inhibition of Secreted Phospholipase A2. 4-Glycerol Derivatives of 4,5-Dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one with Broad Activities

Secreted phospholipases A2 (sPLA2s) have been reported to play an important role in various inflammatory conditions and thus represent an attractive therapeutic target. Previous SAR studies from our laboratory have revealed certain important features of our recently discovered specific hGIIA sPLA2 inhibitors, and we report here the synthesis and biological activities of glycerol-containing derivatives of our lead compound III (Figure 1). Efficient and selective synthesis methods have been developed to make glycerol trisubstituted by different groups on desired positions. In terms of biological activities, the best compounds (A3, A6, and A15) are more active than III (Figure 1), as potent as Me-Indoxam, an sPLA2s inhibitor of reference, against hGIIA, hGV, and hGX sPLA2s and at least 10 times less active toward the GIB enzymes in two in vitro assay systems. By synthesis of enantiopure (S)-A6, we demonstrated that no important improvement of the inhibitory potency could be achieved by this approach. Furthermore, the results show that the global lipophilicity is likely responsible for the anti-PLA2 activity and two oxadiazolone moieties seem too big to be accommodated by the active site of the hGIIA enzyme.

Pharmacological profile of PMS777, a new AChE inhibitor with PAF antagonistic activity

The key pathophysiological mechanisms in Alzheimer's disease involve the selective loss of cholinergic neurons and pro-inflammatory mediator-related chronic inflammatory responses in the brain, therefore interventions of these processes are crucial to the treatment of this disease. In the present study, the pharmacological profile of PMS777, a new acetylcholinesterase (AChE) inhibitor with platelet-activating factor (PAF) antagonistic activity, has been evaluated in vitro and in vivo. PMS777 (1-100 microM) dose-dependently inhibited PAF-induced rabbit platelet aggregation by competing with [3H]PAF for its receptor on platelets, and protected a human neuroblastoma cell line SH-SY5Y against PAF-induced neurotoxicity. Moreover, it markedly inhibited brain AChE activity in mice and showed a modest selectivity for AChE (AChE: IC50=2.48+/-0.12 microM; butyrylcholinesterase: IC50=4.47+/-0.15 microM). Ex vivo, PMS777 (5, 10, 20 or 40 mg/kg i.p.) reduced brain AChE activity in a dose-dependent manner. In-vivo studies revealed that PMS777 (0.25, 0.5, 1, 2.5 or 5 mg/kg i.p.) could reverse scopolamine-induced memory retrieval deficits in mice, and displayed a typical bell-shaped dose-response relationship. Taken together, these results demonstrate that PMS777 possesses dual activities for PAF receptor antagonism and AChE inhibition, suggesting that this compound may be a promising lead compound for further investigation related to the treatment for Alzheimer's disease.

Study of PMS777, a new type of acetylcholinesterase inhibitor, in human HepG2 cells. Comparison with tacrine and galanthamine on oxidative stress and mitochondrial impairment

Acetylcholinesterase inhibitors are commonly used as cognitive enhancers for dementia in aged people. Among them, tacrine (THA) but not galanthamine, was shown to exhibit hepatotoxicity which reduces its clinical use. PMS777, both a PAF antagonist and a new potent acetylcholinesterase inhibitor was recently demonstrated to reverse scopolamine-induced amnesia in mice without toxicity. In the present study, the effects of THA, galanthamine and PMS777 were compared in HepG2 cells on the oxidative parameters involved in the reported hepatotoxicity of THA. THA (> or = 10 microM) induced an oxidative stress as shown by elevated ROS and MDA production and by a decrease in GSH level. Moreover, mitochondrial membrane potential and redox status were decreased. At low concentrations (< or =10 microM), there was no significant disturbance. None of the oxidative stress markers was affected by PMS777 up to the maximum concentration tested and it is suggested that PMS777 is not cytotoxic for HepG2 cells. Galanthamine was also without cytotoxicity. Our results suggest that the toxic effect of THA above 10 microM may be caused by drug-induced mitochondrial energization impairment and destabilisation of membrane phospholipids associated with an oxidative stress. In contrast by preventing these dysfunctions, PMS777 could be safer than THA.

Differential effect of PMS777, a new type of acetylcholinesterase inhibitor, and galanthamine on oxidative injury induced in human neuroblastoma SK-N-SH cells

In the search for highly selective and potent cholinesterase inhibitors (AChEI) being able to improve oxidative injury, PMS777, a tetrahydrofuran derivative, was designed as a novel dual PAF and acetylcholinesterase inhibitor. The aim of this study was to investigate the modulatory effects of PMS777 and galanthamine, another AChEI, on the oxidative injury induced in neuronal cells. The SK-N-SH cells stimulated with LPS+IL-(1beta) were selected to investigate the direct inhibitory effect of PMS777 and galanthamine. LPS+IL-(1beta) induced oxidative injury as assessed by ROS production (29%), GSH depletion (11%) and loss of mitochondrial activity (22%). GSH depletion was never decreased by either drug. In contrast, ROS production and mitochondrial activity were totally prevented by addition of PMS777 but not galanthamine. PMS777 also inhibits butylcholinesterase and it shows selectivity for acetylcholinesterase. Thus, this PAF antagonist inaugurates a new type of AChEI, able to fight oxidative injury. Therefore, PMS777 could be of interest on patients with cognitive impairments and inflammatory damage, as in AD.

Inhibition of secretory phospholipase A. 1-Design, synthesis and structure–activity relationship studies starting from 4-tetradecyloxybenzamidine to obtain specific inhibitors of group II sPLAs

Starting from 4-tetradecyloxybenzamidine (PMS815), a non-specific inhibitor of GI and GII PLA2s, we report in this work the discovery of the specificity through design, synthesis and structure-activity relationships studies of different kinds of PMS815 derivatives. The leading compound, 4,5-dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one (9b, PMS1062) exhibits a micromolar IC50 towards three group II PLA2s, while inactive towards four group I and one group III enzymes in two in vitro enzymatic assay conditions. It is also able to block the PLA2-II activities induced by LPS and IL-6 in HepG2 cell line and no cytotoxicity is observed when PMS1062 is tested up to a concentration of 100 microM in two different cell lines (A549 and LLC-PK1).

Inhibition of secretory phospholipase A2. 2-Synthesis and structure–activity relationship studies of 4,5-dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one (PMS1062) derivatives specific for group II enzyme

We have recently reported the discovery of a series of specific inhibitors of human group IIA phospholipase A(2) (hGIIA PLA(2)) to display promising in vitro and in vivo properties. Here we describe the influence of different structural modifications on the specificity and potency against hGIIA PLA(2) versus porcine group IB PLA(2). The SAR results, as well as the logP and pK(a) values of oxadiazolone determined in this work, provide important information towards the comprehension of the mode of action of this kind of compounds.

In vitro Assessment of Renal Toxicity and Inflammatory Events of Two Protein Phosphatase Inhibitors Cantharidin and Nor-Cantharidin*

In China, cantharidin has been reported to be active against various human cancers, but with severe side effects such as nephrotoxicity. In order to reduce this toxicity, its demethylated analogue nor-cantharidin has been synthesized and used in cancer therapy, but with only few data regarding safety assessment. The aim of this study was to compare the in vitro effects of cantharidin and nor-cantharidin on renal toxicity and on inflammatory events associated with tumoural process where protein phosphatases could be involved (energy status, prostanoid production, glutathione and nitrite contents) on RAW 264.7 and LLC-PK1 cells. In macrophages, both cantharidin and nor-cantharidin decreased cell viability, in a concentration- and time-dependent manner. However, IC50 was lower with cantharidin than with nor-cantharidin. These two drugs significantly decreased the ATP level after 24 hr incubation. However, ATP decreased much more with cantharidin (up to 4 times) than with nor-cantharidin. When control macrophages were activated with lipopolysaccharide+interferon-gamma for 24 hr a significant increase in nitrite content and in prostanoids were observed. Addition of either drug decreased nitrite generation and prostanoids, however these decreases were greater with cantharidin than with nor-cantharidin. In LLC-PK1 cells, incubated with either cantharidin or nor-cantharidin, our results show significant differences between the two drugs, similar to those observed in peritoneal macrophages, except for GSH content with opposite variations in both cells. We provide a better understanding of the various mechanisms of cantharidin side effects, allowing an easier comparison with nor-cantharidin which could be an attractive therapeutic potential in cancer chemotherapy in western countries.

Effects of 24R,25-dihydroxyvitamin D3 on alkaline phosphatase activity in pig renal epithelial LLC-PK1 cells in culture

1. The effects of 24R,25-dihydroxyvitamin D3 [24,25(OH)2D3] on alkaline phosphatase activity (ALP) were evaluated in pig kidney LLC-PK1 cells in culture. 2. The vitamin D3 metabolite increased ALP activity in these cells, whereas no effect of the hormone was observed on gamma-glutamyltranspeptidase and acid phosphatase activities. 3. ALP activity was stimulated after 3- to 12-hr incubation in the presence of 10(-9) mol/l 24,25(OH)2D3 with a maximum after 6 hr. 4. The hormonal induction of ALP activity was prevented by pretreatment of cells by actinomycin D. 5. It is proposed that 24,25(OH)2D3 could increase ALP activity by de novo protein synthesis.

Enantioselective high-performance liquid chromatography determination of methadone enantiomers and its major metabolite in human biological fluids using a new derivatized cyclodextrin-bonded phase

The simultaneous determination of methadone (Mtd) enantiomers and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), in human urine and serum by enantioselective HPLC using a new Cyclobond 1-2000 RSP column is described. After alkaline extraction from urine or serum with estazolam as an internal standard, Mtd enantiomers and its metabolite (EDDP) are separated on the previous column with reversed-mobile phase and detected at 210 nm. Peak resolutions are about 2.0 for Mtd enantiomers. The relative standard deviations (R.S.D.) of Mtd and EDDP standards are between 0.5 and 4.5%. Most drugs of abuse are shown not to interfere with this technique. The method has been applied to study the levels of each Mtd enantiomer and of its racemic metabolite in urine and serum of patients under maintenance treatment for opiate dependence. In urine, R-(-)-Mtd levels are always higher (about 2+/-0.5-fold) than those of S-(+)-Mtd and in most cases, metabolite concentrations are greater than those of global Mtd enantiomers. However, the R-(-) enantiomer levels of residual drug in serum of some patients were lower than those of its antipode. This method is suitable for pharmacokinetic and toxicological studies of Mtd enantiomers and its major metabolite in biological fluids.

Preventive effects of two PAF-antagonists, PMS 536 and PMS 549, on cyclosporin-induced LLC-PK1 oxidative injury

The present study was undertaken to evaluate the effects of platelet activating factor (PAF) antagonists, PMS 536 and PMS 549, on LLC-PK1 toxicity induced by Cyclosporin A (CsA). The LLC-PK1 cell line was used as an in vitro model. CsA cytotoxicity was determined in relation with ATP content. Alkaline phosphatase and N-acetyl-beta-glucosaminidase activities, which are directly correlated with tubular cell damage, were used as markers for renal injury. CsA alone provoked in the LLC-PK1 cell line a marked decrease in cell viability (55%) and membrane integrity (56%), and a significant increase in AP and NAG activities and in oxidized glutathione level. The ATP decrease and the ADP increase, resulting in a decline of the ATP/ADP ratio, is indicative of an anoxic energy charge. Co-treatment with CsA plus PMS 536 or PMS 549 resulted in a minor decrease in cell viability and in significant membrane integrity recovery. Moreover, the ATP depletion and the increase in ATP metabolites, hypoxanthine and uric acid induced by CsA were strongly prevented by PAF antagonists. In contrast, GSSG level remained high as in CsA-treated cells, but GSH level was in the range of controls. Our results suggest that both PAF antagonists attenuate CsA oxidative injury and prevent energy metabolism disturbances probably by maintaining cell integrity. The lipophilicity of both molecules may be responsible for membrane stabilization and may confer the protective effects observed in energy metabolism. The results obtained with PMS 536 and PMS 549 are indicative of interactions between PAF and CsA in renal injury and suggest the therapeutic potential of these PAF-antagonists against CsA-induced nephrotoxicity.

Modulation of energy status and cytotoxicity induced by FK506 and cyclosporin A in a renal epithelial cell line

FK506 and cyclosporin A (CsA) are two potent immunosupressants with similar toxicity profile. Nephrotoxicity is the main adverse effect of both compounds. The aim of this study is to compare the in vitro nephrotoxic effects on renal epithelial cell line LLC-PK1 by measuring cell viability and energy status as evaluated by concentrations of ATP and ATP metabolites. Cell viability (expressed as IC50 was assessed via thiazolyl blue (MTT) assay after incubation for 4-24 h with FK506 or CsA. ATP and its metabolites were determined by HPLC after 4 and 6 h incubation with FK506 or CsA alone at the respective IC50. Both FK506 and CsA decreased cell viability to similar extents, in a dose- and time-dependent manner. After 4 h incubation, both drugs decreased ATP levels (-25%) and increased uric acid levels. However, the latter percentage increase was twofold higher with CsA (18%) than with FK506 (9%). The energy charge, calculated according to levels of adenine nucleotides, was decreased by 10% in FK506-treated cells and by 27% in CsA-treated cells. At the end of 6-h incubation, FK506-treated cells maintained ATP levels coupled with energy charge at near control levels whereas the levels were 32% lower in CsA treated cells. Compared to the 4 h-incubation, the increase in uric acid was similar for FK506 but was doubled with CsA. The decrease in cell integrity and ATP depletion induced by CsA in LLC-PK1 cells was only transiently observed with FK506. By preserving energy status, FK506 leads to fewer metabolic disturbances than CsA in the renal epithelial cell line LLC-PK1, demonstrating a minor potential nephrotoxicity.

1 alpha,25-dihydroxyvitamin D3 stimulated alkaline phosphatase activity in cultured pig kidney epithelial LLC-PK1 cells

The effects of 1 alpha,25-dihydroxyvitamin D3 (1,25 (OH)2D3) and human growth hormone (hGH) on the activity of alkaline phosphatase (ALP) were evaluated in pig kidney LLC-PK1 cultured cells. 1,25(OH)2D3 (10(-9)-10(-6) mol L-1) and hGH (10(-7) mol L-1) increased ALP activity in these cells while no hormonal effect was detected on two other enzyme activities: gamma-glutamyl transferase and acid phosphatase. ALP activity was maximally increased after 4.5-6 h incubation with both hormones. The hormonal induction of ALP activity was prevented by a pretreatment of cells with actinomycin D. Thus, 1,25 (OH)2D3 and may be hGH could stimulate ALP activity via a transcription of some gene.

Structure-activity relationships in platelet-activating factor (PAF). 8. Tetrahydrofuran derivatives as dual PAF antagonists and acetylcholinesterase inhibitors: anti-acetylcholinesterase activity and comparative SAR

2,5-disubstituted tetrahydrofuran derivatives display a dual functionality: they are PAF antagonists and acetylcholinesterase (AChE) inhibitors. In vitro anti-AChE activity and in vivo trials are presented herein. These compounds are competitive and potent AChE inhibitors. Structure-activity relationships are described and compared with PAF-antagonist results. The presence of an onium group, a suitable distance supplied by a chain of 7 or 10 carbon atoms separating the function from the polar head and an appreciable chain hydrophobicity (4 < sigma f < 7) are the main features required for a dual activity. The derivatives are evaluated in a mouse passive avoidance model. Only compounds with both activities are able to reverse scopolamine-induced amnesia. In addition, they display a very weak toxicity.

Effects of cyclosporin on kidney glutathione metabolism and cytochrome P-450 in the rabbit: possible implication of eicosanoid metabolism

This study was designed to assess Cyclosporin A (CsA) nephrotoxicity in the rabbit-possibly a more sensitive species than the rat-and to explore the mechanism of this toxicity with special attention to glutathione metabolism disturbances and cytochrome P-450 level in the kidney. CsA given for three days at a daily dose of 50 mg/kg (s.c.) induced nephrotoxicity as assessed by histological abnormalities and by a significant increase in blood urea nitrogen and urinary enzyme activities: N-acetyl-beta-D-glucosaminidase and L-gamma-glutamyl-transferase. This observed renal injury was of the same order as that obtained in the rat. In addition, there was a significant increase in oxidized glutathione content (40%) while reduced glutathione level remained unchanged. Concurrently, there was a significant decrease in renal cortex glutathione reductase (49%) and to a lesser extent in glutathione peroxidase activities (16%) whereas that of glutathione-S-transferase was not modified. A significant increase in renal cortex cytochrome P-450 (3-fold versus controls) was also observed. The mechanism of CsA nephrotoxicity is to be related to a cytochrome P-450 induction. This event could induce the observed impairments in renal glutathione metabolism and Na+K(+)-ATPase activity, via a possible increase in eicosanoid metabolism.

Protection against cyclosporin-induced nephrotoxicity: 1. Effect of a PAF antagonist, BN50726

The clinical usefulness of cyclosporin A (CsA) in organ transplantation is limited by its intrinsic nephrotoxicity, the mechanisms of which have not yet been completely elucidated. Various processes could be responsible for the CsA-induced nephrotoxicity including an interaction with glutathione metabolism, a lipoperoxidative process, or an interaction with platelet-activating factor (PAF). Therefore, the aim of this study was to assess the potential role of PAF in CsA-induced nephrotoxicity using a new PAF antagonist, BN50726. CsA alone provoked a significant increase in serum urea, urinary gamma-glutamyl transferase activity and oxidized glutathione level of kidney cortex in the rat. In contrast, when rats were treated with CsA plus BN50726, urinary gamma-glutamyltransferase activity was similar to that of controls and oxidized glutathione was significantly lower than that measured in rats treated with CsA alone. However, serum urea remained increased as it was in the CsA group. Our results suggest that BN50726 is able to prevent the damage of renal membranes probably by an antiperoxidative activity. These data indicate the potential therapeutic capacity of a PAF antagonist, BN50726, in reducing CsA nephrotoxicity and suggest interactions between PAF and CsA in the mechanism of renal injury.

Structure-activity relationships in platelet-activating factor (PAF antagonists). 6. Synthesis and in vitro antagonistic activities of 2-substituted 5-oxotetrahydrofurans

The synthesis of 2,5-disubstituted tetrahedrofuran compounds as potential in vitro PAF antagonists is described. Results demonstrate that the structural requirements for potent PAF antagonist activity are: a moderate lipophilic group or a trimethoxyphenyl group in position-5, and a long aliphatic chain terminated by a cationic polar head in position-2. The cis-trans configuration does not induce any difference in biological activity. Some conformational features of the putative PAF receptor are proposed in light of the present findings.

Structure-activity relationships in platelet-activating factor (PAF). 5. Synthesis and in vitro antagonistic activities of ketophosphonates

The synthesis of new ketophosphonate isosteres of biosynthetic precursors of ether glycerophospholipids resistant to phospholipase C is described following two routes depending on whether the alkoxy chain is introduced before or after the phosphonic moiety. The common intermediates are ketophosphonic acids: better yields were obtained by attaching the n-octadecyl chain to epichlorohydrin, opening and oxidation, blockage of the resulting ketone as the chlorohydrazone, followed by an Arbuzov reaction or by azoene formation and Michael addition. These ketophosphonates differing in chain length in position 3 exhibit potent agonistic activities on rabbit platelets which increase with the number of methylene groups between the phosphonate and the ammonium moieties.

Effects of a new anorectic drug (PM 170) on development of gold thioglucose-induced obesity in mice

Gold thioglucose (GTG)-injected mice and lean mice were treated for 16 days with PM 170. The body weight and body fat were significantly increased by GTG injection and these increases in the GTG-obese group were reduced by PM 170. PM 170 also reduced food intake (16%), total body triacylglycerol (51%) and total body cholesterol (36%). Basal lipolysis of white adipose tissue, as measured by glycerol release, was stimulated by 150%. Compared to GTG-PM 170 mice, body weight gain was 2 times higher in GTG-pair-fed mice. Body fat and total body lipid content remained elevated.

Activation of energy expenditure in the rat by a new non-amphetaminic compound: the (4-chlorophenoxyacetate) N-methyl 3-hydroxymethyl piperidine, hydrochloride (PM 170)

The (4-chlorophenoxyacetate) N-methyl 3-hydroxymethyl piperidine, hydrochloride (PM 170), chemically unrelated to amphetamine, was studied in normal rats for any thermogenic effect. It was given in graded doses. After an acute treatment PM 170 increases energy expenditure by increasing resting oxygen consumption (VO2) and in the doses used, produced dose-related increases in VO2. Energy expenditure of rats treated for 16 days was chronically elevated, while body weight gain and food intake were reduced. It also stimulated mitochondrial oxygen consumption probably by partial uncoupling of respiration from ATP synthesis. The disruption of oxidative phosphorylation could partially explain the effect of this compound on resting metabolic rate.