Serum myoglobin/carbonic anhydrase III ratio as a marker of reperfusion after myocardial infarction

The potential of carbonic anhydrase enzymes as a novel target for anti-cancer treatment

Carbonic anhydrase (CA) is a zinc-dependent metal enzyme that maintains the pH and carbon dioxide (CO2) homeostasis in cells by catalyzing the reversible hydration and dehydration of CO2 and bicarbonate (HCO3-). In mammals, there are 16 isozymes of CA existed, namely CAI to CAXIV, but only 15 isozymes are found in humans except CAXV. Human CAs have highly conserved catalytic domains, all of which are distributed in different tissues and play important physiological roles. Changes in their functions may disrupt the typical distribution of CAs throughout human body and therefore CAs can be used as diagnostic biomarkers for many diseases. Furthermore, the expression of CAs is correlated to the progression of numerous tumors, therapeutic sensitivity and patient prognosis. In this review, we discuss thoroughly the structure of CAs, their functional activities in human physiology, dysregulations and diseases related to CAs, and different types of CA inhibitors that can reverse their dysregulation.

Characterization of Carbonic Anhydrase In Vivo Using Magnetic Resonance Spectroscopy

Carbonic anhydrase is a ubiquitous metalloenzyme that catalyzes the reversible interconversion of CO2/HCO3-. Equilibrium of these species is maintained by the action of carbonic anhydrase. Recent advances in magnetic resonance spectroscopy have allowed, for the first time, in vivo characterization of carbonic anhydrase in the human brain. In this article, we review the theories and techniques of in vivo 13C magnetization (saturation) transfer magnetic resonance spectroscopy as they are applied to measuring the rate of exchange between CO2 and HCO3- catalyzed by carbonic anhydrase. Inhibitors of carbonic anhydrase have a wide range of therapeutic applications. Role of carbonic anhydrases and their inhibitors in many diseases are also reviewed to illustrate future applications of in vivo carbonic anhydrase assessment by magnetic resonance spectroscopy.

Carbonic anhydrases as disease markers

INTRODUCTION

The physiologic importance of fast CO₂/HCO₃^- interconversion in various tissues requires the presence of carbonic anhydrase (CA, EC 4.2.1.1). Fourteen CA isozymes are present in humans, all of them being used as biomarkers.

AREAS COVERED

A great number of patents and articles were focused on the use of CA isozymes as biomarkers for various diseases and syndromes in the recent years, in an ascending trend over the last decade. The review highlights the most important studies related with each isozyme and covers the most recent patent literature.

EXPERT OPINION

The CAs biomarker research area expanded significantly in recent years, shifting from the predominant use of CA IX and CA XII in cancer diagnostic, staging, and prognosis towards a wider use of CA isozymes as disease biomarkers. CA isozymes are currently used either alone, in tandem with other CA isozymes and/or in combination with other proteins for the detection, staging, and prognosis of a huge repertoire of human dysfunctions and diseases, ranging from mild transformation of the normal tissues to extreme shifts in tissue organization and function. The techniques used for their detection/quantitation and the state-of-the-art in each clinical application are presented through relevant clinical examples and corresponding statistical data.

Cathepsin A inhibition attenuates myocardial infarction-induced heart failure on the functional and proteomic levels

Background

Myocardial infarction (MI) is a major cause of heart failure. The carboxypeptidase cathepsin A is a novel target in the treatment of cardiac failure. We aim to show that recently developed inhibitors of the protease cathepsin A attenuate post-MI heart failure.

Methods

Mice were subjected to permanent left anterior descending artery (LAD) ligation or sham operation. 24 h post–surgery, LAD-ligated animals were treated with daily doses of the cathepsin A inhibitor SAR1 or placebo. After 4 weeks, the three groups (sham, MI-placebo, MI-SAR1) were evaluated.

Results

Compared to sham-operated animals, placebo-treated mice showed significantly impaired cardiac function and increased plasma BNP levels. Cathepsin A inhibition prevented the increase of plasma BNP levels and displayed a trend towards improved cardiac functionality. Proteomic profiling was performed for the three groups (sham, MI-placebo, MI-SAR1). More than 100 proteins were significantly altered in placebo-treated LAD ligation compared to the sham operation, including known markers of cardiac failure as well as extracellular/matricellular proteins. This ensemble constitutes a proteome fingerprint of myocardial infarction induced by LAD ligation in mice. Cathepsin A inhibitor treatment normalized the marked increase of the muscle stress marker CA3 as well as of Igγ 2b and fatty acid synthase. For numerous further proteins, cathepsin A inhibition partially dampened the LAD ligation-induced proteome alterations.

Conclusions

Our proteomic and functional data suggest that cathepsin A inhibition has cardioprotective properties and support a beneficial effect of cathepsin A inhibition in the treatment of heart failure after myocardial infarction.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0907-8) contains supplementary material, which is available to authorized users.

Chromatographic evaluation and QSAR optimization for benzoic acid analogues against carbonic anhydrase III

An HPLC-size exclusion method was developed as an assay method to evaluate the binding of tested compounds with carbonic anhydrase III (CAIII) enzyme. Inhibition of CAIII by a group of benzoic acid analogues was characterized by vacancy (negative) peak intensity representing the fraction of the compounds bound with CAIII enzyme. Interestingly, p-hydroxyl benzoic acid and aspirin were found potent inhibitors against CAIII with affinity constants of 9954 and 9013 M(-1) respectively. Affinity values of twenty training compounds were modeled against thirty-five descriptors derived from their structures. Strong correlation was obtained between the affinity values and the formal charge of the molecules. Docking studies on training set compounds generated consensus scores having a strong agreement with affinity factors obtained from the chromatographic analysis.

Evaluation of vanillic acid as inhibitor of carbonic anhydrase isozyme III by using a modified Hummel-Dreyer method: approach for drug discovery

α-3 carbonic anhydrase isozyme (CAIII) is the most abundant protein in adipocytes and considered insensitive to sulfonamide inhibitors. It was reported recently that the knock-down of CAIII is attributed with controlling lipogenesis. Thus inhibition of this target may lead to the discovery of new therapies against obesity and insulin resistance. Vanillic acid as a small molecule with coordinating groups and has a potential to bind zinc atoms in CA binding sites. Inhibition of CAIII by vanillic acid was evaluated by Hummel-Dreyer chromatography because it provides free interaction between ligand and macromolecule and introduces solution for faulty results obtained by current colorimetric assays. HPLC system of vanillic acid produces vacancy (negative) peak representing the amount of attached vanillic acid with CAIII. It was found that vanillic acid is able to bind with CAIII through two equilibria, one at equimolar ratio and another at 2:1 (vanillic acid-CAIII) ratio. The affinity constant of equimolar binding between CAIII and vanillic acid was found to be 14,400 m(-1) . It was found that vanillic acid binding with CAIII is much stronger than phenol and acetazolamide (positive controls).

Biochemical markers of myocardial injury

The serum markers of myocardial injury are used to help in establishing the diagnosis of myocardial infarction. The older markers like aspartate amino-transferase, creatine kinase, lactate dehydrogenase etc. lost their utility due to lack of specificity and limited sensitivities. Among the currently available markers cardiac troponins are the most widely used due to their improved sensitivity specificity, efficiency and low turn around time. Studies have shown that cardiac troponins should replace CKMB as the diagnostic 'gold standard' for the diagnosis of myocardial injury. The combination of myoglobin with cardiac troponins has further improved the accuracy in the diagnosis of acute coronary syndromes and thereby reducing the hospital stay and patients' money. Among the other new markers of early detection of myocardial damage, heart fatty acid binding protein, glycogen phosphorylase BB and myoglobin/carbonic anhydrase III ratio seem to be the most promising. But the search for the most ideal marker of myocardial injury is still on.

Molecular characterization and association analysis of porcine CA3

Carbonic anhydrase 3 (CA3) is a member of the carbonic anhydrase family, which plays an important role in various cell processes. In this paper, molecular characterization revealed that CA3 genomic DNA consists of seven exons and six introns, spans about 10.5 kb and maps to porcine chromosome 4q11-->q14. Results of expression profiles showed that the expression levels of CA3 increased in skeletal muscles from prenatal 33- to 65-day-old Chinese Tongcheng pigs. These levels subsequently decreased to a steady state in prenatal 90-day-old, postnatal 2-day-old, postnatal 28-day-old, and pregnant 65-day-old pigs. The expression patterns of Chinese Tongcheng pig embryos were different from that of Landrace pig embryos. CA3 was expressed at higher levels in skeletal muscle and liver than in kidney, lung, stomach, intestine, and brain, but was not detected in heart and spleen. Statistical analysis showed the CA3 gene polymorphism was different between Chinese indigenous and introduced commercial western pig breeds, and was associated with intramuscular fat content and percentage of ham of pigs.

Proteomic approach to the diagnosis of acute coronary syndrome: Preliminary results

BACKGROUND

Cardiac multimarker strategy is recommended by the IFCC, ESC and the ACC for an early risk stratification in non-ST-segment elevation (NSTE) ECG patients with chest pain. A new approach, based on protein biochip array technology, performs simultaneously: cTnI, CK-MB, myoglobin, CAIII, GFBB and FABP using a single chip.

METHODS

We evaluated the analytical performance of the Randox-Evidence Investigator -biochip cardiac panel according to IFCC recommendations and NCCLS guidelines; a preliminary clinical evaluation was carried out on chest pain NSTE ECG patients, to evaluate the accuracy of the multimarker approach in an early diagnosis of AMI, related to the final diagnosis (ACC/ESC criteria).

RESULTS

Troponin, CK-MB and FABP methods provide reproducible within-run and between-day results (total % CVs from 5.9% to 9.7%), and myoglobin and CAIII methods showed the total % CVs from 16.4% to 25.8%. Our preliminary clinical data suggests that FABP had a better diagnostic performance (sensibility = 100%) than myoglobin (sensibility = 75%) to detect AMI in the first hours after the onset of the chest pain and myoglobin/CAIII ratio (specificity = 92.9%) improved the myoglobin specificity.

CONCLUSIONS

Cardiac markers have different diagnostic roles and, in this contest, biochip technology could be an interesting approach supporting clinical expectations.