MC-1 (pyridoxal 5'-phosphate): novel therapeutic applications to reduce ischaemic injury

Identification of biomarkers and candidate small-molecule drugs in lipopolysaccharide (LPS)-induced acute lung injury by bioinformatics analysis

BACKGROUND/OBJECTIVE

Acute lung injury (ALI) is a critical clinical syndrome with high rates of incidence and mortality. However, its molecular mechanism remains unclear. The current work aimed to explore the molecular mechanisms of ALI by identifying different expression genes (DEGs) and candidate drugs using a combination of chip analysis and experimental validation.

METHODS

Three microarray datasets were downloaded from Gene Expression Omnibus (GEO) database to obtain DEGs. We conducted a Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway-enrichment analyses of overlapping DEGs among three databases. The expression level of key gene was verified by Western blotting analysis in LPS-treated ALI cell models. Finally, we predicted the candidate drugs targeting the key gene that might be effective for ALI treatment, and the role of candidate drug in treating ALI was verified by investigation.

RESULTS

A total 29 overlapping DEGs were up-regulated in LPS-induced ALI groups. They were enriched in inflammation and inflammation-related pathways. Serpin family A member 3 (SERPINA3) was defined as a key gene because it was associated with inflammation pathway and up-regulated in microarray datasets in LPS-induced ALI. In LPS-induced human bronchial epithelial cells transformed with Ad12-SV40-2B (BEAS-2B) cells, SERPINA3 was enhanced. Pyridoxal phosphate as an upstream drug of SERPINA3 could improve cell viability and reduce expression inflammatory factors in LPS-treated BEAS-2B cells.

CONCLUSION

Our study suggested that pyridoxal phosphate could be a candidate drug targeting SERPINA3 gene in LPS-induced ALI. It has protective and anti-inflammatory effects in BEAS-2B cells, and may become a potential novel treatment for ALI.

Vitamin B6 Alleviates Lipopolysaccharide-induced Myocardial Injury by Ferroptosis and Apoptosis Regulation

Vitamin B6 (VitB6) is a water-soluble vitamin and includes pyridoxine, pyridoxal, pyridoxamine, and their phosphorylated forms. In the current study, we demonstrated that VitB6 could improve lipopolysaccharide (LPS)-induced myocardial injury. We demonstrated that VitB6 can suppress LPS-induced oxidative stress and lipid peroxidation that lead to ferroptosis and apoptosis in vivo and in vitro. Moreover, we found that VitB6 can regulate the expression of iron regulatory proteins, maintaining intracellular iron homeostasis. To confirm that VitB6 could inhibit LPS-induced ferroptosis and apoptosis, we pretreated mice with ferrostatin-1 (Fer-1) and emricasan that efficiently mimicked VitB6 pharmacological effects. This improved the survival rate of mice challenged with a high LPS dose. In addition, VitB6 regulated the expression of LPS-induced apoptosis-related proteins and iron regulatory proteins. It mediated the expression of Nrf2, transcription factor NF-E2-related factor 2, which promoted the expression of antioxidant enzymes and restrained LPS-induced ferroptosis and apoptosis. Overall, our results indicated that VitB6 can be used on novel therapies to relieve LPS-induced myocardial injury.

Effectiveness of Some Vitamins in the Prevention of Cardiovascular Disease: A Narrative Review

By virtue of their regulatory role in various metabolic and biosynthetic pathways for energy status and cellular integrity, both hydro-soluble and lipo-soluble vitamins are considered to be involved in maintaining cardiovascular function in health and disease. Deficiency of some vitamins such as vitamin A, B₆, folic acid, C, D, and E has been shown to be associated with cardiovascular abnormalities whereas supplementation with these vitamins has been claimed to reduce cardiovascular risk for hypertension, atherosclerosis, myocardial ischemia, arrhythmias, and heart failure. However, the data from several experimental and clinical studies for the pathogenesis of cardiovascular disease due to vitamin deficiency as well as therapy due to different vitamins are conflicting. In this article, we have attempted to review the existing literature on the role of different vitamins in cardiovascular disease with respect to their deficiency and supplementation in addition to examining some issues regarding their involvement in heart disease. Although both epidemiological and observational studies have shown some merit in the use of different antioxidant vitamins for the treatment of cardiovascular disorders, the results are not conclusive. Furthermore, in view of the complexities in the mechanisms of different cardiovascular disorders, no apparent involvement of any particular vitamin was seen in any specific cardiovascular disease. On the other hand, we have reviewed the evidence that deficiency of vitamin B₆ promoted KCl-induced Ca²⁺ entry and reduced ATP-induced Ca²⁺-entry in cardiomyocytes in addition to decreasing sarcolemmal (SL) ATP binding. The active metabolite of vitamin B₆, pyridoxal 5′-phosphate, attenuated arrhythmias due to myocardial infarction (MI) as well as cardiac dysfunction and defects in the sarcoplasmic reticulum (SR) Ca²⁺-transport in the ischemic-reperfused hearts. These observations indicate that both deficiency of some vitamins as well as pretreatments with different vitamins showing antioxidant activity affect cardiac function, metabolism and cation transport, and support the view that antioxidant vitamins or their metabolites may be involved in the prevention rather than the therapy of cardiovascular disease.

Pyridoxamine improves survival and limits cardiac dysfunction after MI

Advanced glycation end products (AGEs) play a key role in the progression of heart failure. Whether treatments limiting AGEs formation would prevent adverse left ventricular remodeling after myocardial infarction (MI) remain unknown. We investigated whether pyridoxamine (PM) could limit adverse cardiac outcome in MI. Rats were divided into MI, MI + PM and Sham. Echocardiography and hemodynamic parameters were used to assess cardiac function 8 weeks post-surgery. Total interstitial collagen, collagen I and collagen III were quantified using Sirius Red and polarized light microscopy. PM improved survival following LAD occlusion. Pre-treatment with PM significantly decreased the plasma AGEs levels. MI rats treated with PM displayed reduced left ventricular end-diastolic pressure and tau compared to untreated MI rats. Deformation parameters were also improved with PM. The preserved diastolic function was related to the reduced collagen content, in particular in the highly cross-linked collagen type I, mainly in the peri-infarct region, although not via TGF-β1 pathway. Our data indicate that PM treatment prevents the increase in AGEs levels and reduces collagen levels in a rat model of MI, resulting in an improved cardiac phenotype. As such, therapies targeting formation of AGEs might be beneficial in the prevention and/or treatment of maladaptive remodeling following MI.

Vitamin D prevents hypoxia/reoxygenation-induced blood-brain barrier disruption via vitamin D receptor-mediated NF-kB signaling pathways

Maintaining blood-brain barrier integrity and minimizing neuronal injury are critical components of any therapeutic intervention following ischemic stroke. However, a low level of vitamin D hormone is a risk factor for many vascular diseases including stroke. The neuroprotective effects of 1,25(OH)2D3 (vitamin D) after ischemic stroke have been studied, but it is not known whether it prevents ischemic injury to brain endothelial cells, a key component of the neurovascular unit. We analyzed the effect of 1,25(OH)2D3 on brain endothelial cell barrier integrity and tight junction proteins after hypoxia/reoxygenation in a mouse brain endothelial cell culture model that closely mimics many of the features of the blood-brain barrier in vitro. Following hypoxic injury in bEnd.3 cells, 1,25(OH)2D3 treatment prevented the decrease in barrier function as measured by transendothelial electrical resistance and permeability of FITC-dextran (40 kDa), the decrease in the expression of the tight junction proteins zonula occludin-1, claudin-5, and occludin, the activation of NF-kB, and the increase in matrix metalloproteinase-9 expression. These responses were blocked when the interaction of 1,25(OH) )2D3 with the vitamin D receptor (VDR) was inhibited by pyridoxal 5'-phosphate treatment. Our findings show a direct, VDR-mediated, protective effect of 1,25(OH) )2D3 against ischemic injury-induced blood-brain barrier dysfunction in cerebral endothelial cells.

Pathogenesis of myocardial ischemia-reperfusion injury and rationale for therapy

Since the initial description of the phenomenon by Jennings et al 50 years ago, our understanding of the underlying mechanisms of reperfusion injury has grown significantly. Its pathogenesis reflects the confluence of multiple pathways, including ion channels, reactive oxygen species, inflammation, and endothelial dysfunction. The purposes of this review are to examine the current state of understanding of ischemia-reperfusion injury, as well as to highlight recent interventions aimed at this heretofore elusive target. In conclusion, despite its complexity our ongoing efforts to mitigate this form of injury should not be deterred, because nearly 2 million patients annually undergo either spontaneous (in the form of acute myocardial infarction) or iatrogenic (in the context of cardioplegic arrest) ischemia-reperfusion.

Involvement of P2Y receptors in pyridoxal-5'-phosphate-induced cardiac preconditioning

Using an isolated non-working rat heart model, this study investigated the mechanisms of pharmacological pre-conditioning (PC) induced by P2Y receptor stimulation with pyridoxal-5'-phosphate (PLP). After 6-hydroxydopamine pretreatment and a 15-min stabilization period, isolated rat hearts were perfused for 25 min then subjected to 40 min of global ischemia and 30 min of reperfusion (I/R); exposed for 15 min to 0.05 microM PLP bracketed for 25 min with broad-spectrum P2 antagonists (suramin or PPADS) or with more specific P2Y antagonists (AMPalphaS or MRS2578), 1 microM each, followed by a 5-min PLP-free perfusion before I/R; treated during 25 min with either glybenclamide (GLY, 1 microM), 5-hydroxydecanoic acid (5-HD, 100 microM), U73122 (0.5 microM), H89 (1 microM), or KN93 (1 microM), with an infusion starting 5 min before PLP. The main endpoints were the rate-pressure product (RPP), creatine kinase (CK) release and area necrosis. Recovery of RPP, measured 5 min after reperfusion, was rapidly improved by PLP, blocked by the P2 antagonists, and decreased with the different inhibitors. Fifteen minutes after the end of ischemia, CK release reached maximal values in all groups. PLP provided significant protection, whereas the P2 antagonists, 5-HD, a mitochondrial selective K(ATP) antagonist and GLY a non-selective K(ATP) channel blocker, suppressed the protective effect on myocardial injury. The suppression of the cardioprotective effects of PLP by AMPalphaS, the PKA inhibitor (H89), and phospholipase C blocker (U73122) is in agreement with the P2Y11 receptor as a receptor for PLP-induced PC. The suppression of the cardioprotective effects of PLP by MRS2578 and U73122 is in agreement with the P2Y6 receptor as a receptor for PLP-induced PC. Pre-ischemic exposure to nanomolar concentrations of PLP is protective against I/R. P2Y11 and P2Y6 represents the most likely candidate receptors for PLP-induced cardiac PC.

Natural products to drugs: natural product-derived compounds in clinical trials

Natural product and natural product-derived compounds that are being evaluated in clinical trials or are in registration (as at 31st December 2007) have been reviewed, as well as natural product-derived compounds for which clinical trials have been halted or discontinued since 2005. Also discussed are natural product-derived drugs launched since 2005, new natural product templates and late-stage development candidates.

A randomized, double-blind, placebo-controlled, multicenter study to evaluate the cardioprotective effects of MC-1 in patients undergoing high-risk coronary artery bypass graft surgery: MC-1 to Eliminate Necrosis and Damage in Coronary Artery Bypass Graft Surgery Trial (MEND-CABG) II--study design and rationale

BACKGROUND

Coronary artery bypass graft (CABG) surgery is effective in relieving angina and improving survival and quality of life in patients with obstructive coronary artery disease; however, recurrent angina, myocardial infarction, neurological injury, and death can occur in the perioperative and postoperative period. MC-1 (pyridoxal 5'-phosphate) is a novel agent that has shown promise in reducing myocardial necrosis by reducing cellular calcium overload after percutaneous coronary intervention and CABG surgery in high-risk patients undergoing these procedures.

METHODS

MEND-CABG II is a phase III study evaluating the efficacy and safety of MC-1 in reducing cardiovascular morbidity and mortality after CABG. High-risk patients undergoing CABG surgery will be randomly assigned to receive either MC-1 (250 mg/d) or matching placebo immediately before and continuing for 30 days after the procedure. The primary end point is the occurrence of cardiovascular death or nonfatal myocardial infarction through postoperative day 30. A total of 3023 patients were enrolled at 130 sites in Canada, the United States, and Germany between October 2006 and September 2007, with results anticipated shortly after completion of 90-day follow-up in March 2008.

CONCLUSIONS

The data from the MEND-CABG II trial will establish whether peri- and postoperative treatment with MC-1 can decrease the short- and intermediate-term morbidity and mortality of high-risk patients undergoing CABG surgery.

Effects of pyridoxal-5′-phosphate (MC-1) in patients undergoing high-risk coronary artery bypass surgery: Results of the MEND-CABG randomized study

OBJECTIVE

Coronary artery bypass graft surgery remains associated with significant postoperative cardiovascular morbidity and mortality in high-risk patients. MC-1 (pyridoxal-5'-phosphate monohydrate) inhibits purinergic receptors and intracellular influx of Ca2+, thereby reducing cellular injury during experimental ischemia and reperfusion. The MEND-CABG trial tested the hypothesis that MC-1 reduces cardiovascular morbidity and mortality after coronary artery bypass graft.

METHODS

In a phase 2, double-blinded, placebo-controlled study, 901 patients scheduled for coronary artery bypass graft surgery with cardiopulmonary bypass and at high risk for subsequent cardiac or neurologic complications were randomly assigned to receive oral MC-1 (250 mg or 750 mg/d once daily) or placebo beginning 3 to 10 hours prior to surgery and continued to postoperative day 30.

RESULTS

At 30 days, MC-1 250 mg (compared with placebo) reduced the composite of death, nonfatal cerebral infarction, and nonfatal myocardial infarction by 14.0% (P = .3124) with peak creatinine kinase-myocardial band > or =50 ng/mL (prespecified primary end point); 32.3% (P = .0349) with peak creatinine kinase-myocardial band > or =70 ng/mL; and 37.2% (P = .0283) with peak creatinine kinase-myocardial band > or =100 ng/mL. Myocardial infarctions with peak creatinine kinase-myocardial band> or =100 ng/mL were reduced by 47.2% in the MC-1 250-mg group versus placebo (P = .0083). Greater efficacy was demonstrated with 250 mg than with the 750-mg dose of MC-1.

CONCLUSIONS

In high-risk patients undergoing coronary artery bypass graft, treatment with MC-1 did not significantly affect the prespecified primary end point but was associated with a significant reduction in perioperative myocardial infarction with creatinine kinase-myocardial band > or =100 ng/mL. A larger, well-powered trial is needed to evaluate the cardioprotective effects of MC-1.

Time course of changes in pyridoxal 5'-phosphate (vitamin B6 active form) and its neuroprotection in experimental ischemic damage

In the present study, we investigated ischemia-induced changes of pyridoxal 5'-phosphate synthesizing enzyme and degrading enzyme and neuroprotective effects and roles of pyridoxal 5'-phosphate against ischemic damage in the gerbil hippocampal CA1 region. Pyridoxal 5'-phosphate oxidase and pyridoxal phosphate phosphatase immunoreactivities were changed in neurons up to 2 days after ischemia, while 4 days after ischemia their immunoreactivities were expressed in astrocytes. Pyridoxal 5'-phosphate oxidase immunoreactivity and its protein level were highest 12 h after ischemia, while those in pyridoxal phosphate phosphatase were highest 2 days after ischemia. Total activities of these enzymes were changed after ischemia, but specific activities of the enzymes were not altered. Treatment with pyridoxal 5'-phosphate into brains (4 microg/5 microl, i.c.v.) at 30 min before transient ischemia protected about 80% of CA1 pyramidal cells 4 days after ischemia and induced elevation of glutamic acid decarboxylase 67 immunoreactivity in the CA1 region. However, pyridoxal 5'-phosphate treatment into ischemic brains decreased GABA transaminase immunoreactivity in the CA1 region after ischemia. These results indicate that pyridoxal 5'-phosphate may be associated with the inhibitory discharge of GABA in the hippocampal CA1 neurons, and the increased level of GABA may protect hippocampal CA1 pyramidal cells from ischemic damage.

Testing the homocysteine hypothesis in end-stage renal disease: Problems and a possible solution

The homocysteine hypothesis states that circulating homocysteine is a vascular toxin in concentrations that occur in the general population and in renal failure. This hypothesis is currently being tested in the Kidney and End State Renal Disease Study (HOST), but data have emerged since the HOST began that suggest its results will be inconclusive. The crucial treatment component in the HOST is folic acid, but its effect is likely to be lost because the American food supply is now fortified with folic acid. A second concern is that the very high doses of folic acid and pyridoxine being used in the HOST may confound the results. Finally, confounding due to 'reverse epidemiology' was not considered when the HOST was designed. Parenteral vitamin B(12) is a highly promising therapy for homocysteine reduction in end-stage renal disease that merits careful investigation. Clinical trials using it to test the homocysteine hypothesis will avoid the problems inherent in the HOST.