Detection of His-tagged Long-R³-IGF-I in a black market product

Detection of synthetic analogues of insulin-like growth factor 1 in different biological fluids by liquid chromatography quadrupole time-of-flight mass spectrometry: comparison of different immunoaffinity protocols

Insulin-like growth factor 1 analogues are prohibited in sport for their ability to enhance athletic performance in several sport disciplines. Their detection presents several analytical challenges, mainly due to the minimum required performance limits fixed by the World Anti-Doping Agency. Here, we are presenting analytical workflows to detect IGF-1 and its analogues in different biological matrices. Several off-line immunocapture techniques and protocols were comparatively evaluated. Separation and detection were performed by using standard flow reverse-phase liquid chromatography coupled to a time-of-flight mass spectrometer. The best recoveries were obtained using magnetic beads or pipette tips functionalized with protein A. The analytical workflows were fully validated for qualitative determinations: all the target analytes were clearly distinguishable from the interference of the matrices, with limits of detection and identification in the range of 0.05-0.30 ng/mL in urine and 0.5-2.0 ng/mL in serum/plasma. The extraction efficiency proved to be repeatable (CV% < 10) with recoveries higher than 50%. Intra- and inter-day precision were found to be smaller than 10 and 15%, respectively. The method was successfully applied to the analysis of authentic matrix samples containing the target peptides at the minimum required performance limits, proving that the method developed can be successfully applied to detect and identify IGF-1 analogues for doping control purposes in all the matrices selected. The analytical workflow developed here to detect the target peptides in different matrices can be readily implemented in anti-doping laboratories and has the potential to be adapted for the simultaneous analysis of different similarly sized peptide hormones of doping relevance.

Detection of insulin analogues and large peptides > 2 kDa in urine

Insulin analogues and large bioactive peptides may be used by athletes to enhance performance and are banned by the World Anti-Doping Agency (WADA). In addition to insulin analogues, the large peptides include a structurally diverse set of peptides including analogues of growth hormone releasing hormone (GHRH), insulin-like growth factor-1 (IGF-1), and mechano-growth factor (MGF). Detection of this class of peptides is difficult due to their absorptive losses and presence at very low concentrations in urine. In this report, a high throughput method is described that allows sensitive detection of 4 classes of large peptides in one assay. Sample extraction is performed by ultrafiltration to concentrate the urine followed by solid phase extraction in a 96-well micro-elution plate. Peptides in the urine samples are detected on a triple quadrupole mass spectrometer coupled to standard flow liquid chromatography. The method was validated and evaluated for limit of detection, limit of identification, specificity, precision, carry-over, recovery, matrix interference, and post-extraction stability. The limit of detection for insulin analogues is between 5 - 25 pg/ml and between 5 - 50 pg/ml for the other peptide classes. Specificity was good with no detection of interfering peaks in blank urine samples. Carry-over from a high concentration sample was not observed and the post-extraction stability was between 77 - 107%. The method was able to detect insulin analogues in three diabetic urine samples. Increased screening for this class of peptides will improve detection and deterrence.

Determination of LongR3-IGF-I, R3-IGF-I, Des1-3 IGF-I and their metabolites in human plasma samples by means of LC-MS

According to the regulations of the World Anti-Doping Agency (WADA), growth promoting peptides such as the insulin-like growth factor-I (IGF-I) and its synthetic analogues belong to the class of prohibited compounds. While several assays to quantify endogenous IGF-I have been established, the potential misuse of synthetic analogues such as LongR³-IGF-I, R³-IGF-I and Des1-3-IGF-I remains a challenge and superior pharmacokinetic properties have been described for these analogues. Within the present study, it was demonstrated that the target peptides can be successfully detected in plasma samples by means of magnetic beads-based immunoaffinity purification and subsequent nanoscale liquid chromatographic separation with high resolution mass spectrometric detection. Noteworthy, the usage of a specific antibody for LongR³-IGF-I enables the determination in low ng/mL levels despite the presence of an enormous excess of endogenous human IGF-I. In addition, different metabolism studies (in-vitro and in-vivo) were performed using sophisticated strategies such as incubation with skin tissue microsomes, degradation in biological fluids (for all analogues), and administration to rats (for LongR³-IGF-I). Herewith, several C-and N-terminally truncated metabolites were identified and their relevancy was additionally confirmed by in-vivo experiments with rodents. Especially for LongR³-IGF-I, a metabolite ((Des1-11)-LongR³-IGF-I) was identified that prolonged the detectability in-vivo by a factor of approximately 2. The method was validated for qualitative interpretation considering the parameters specificity, identification capability, recovery (26-60%), limit of detection (0.5ng/mL), imprecision (<25%), linearity, stability, and matrix effects. A stable isotope labelled (¹⁵N)-IGF-I was used as internal standard to control all sample preparation steps.

In Vitro Metabolic Studies of REV-ERB Agonists SR9009 and SR9011

SR9009 and SR9011 are attractive as performance-enhancing substances due to their REV-ERB agonist effects and thus circadian rhythm modulation activity. Although no pharmaceutical preparations are available yet, illicit use of SR9009 and SR9011 for doping purposes can be anticipated, especially since SR9009 is marketed in illicit products. Therefore, the aim was to identify potential diagnostic metabolites via in vitro metabolic studies to ensure effective (doping) control. The presence of SR9009 could be demonstrated in a black market product purchased over the Internet. Via human liver microsomal metabolic assays, eight metabolites were detected for SR9009 and fourteen metabolites for SR9011 by liquid chromatography–high resolution mass spectrometry (LC–HRMS). Structure elucidation was performed for all metabolites by LC–HRMS product ion scans in both positive and negative ionization mode. Retrospective data analysis was applied to 1511 doping control samples previously analyzed by a full-scan LC–HRMS screening method to verify the presence of SR9009, SR9011 and their metabolites. So far, the presence of neither the parent compound nor the metabolites could be detected in routine urine samples. However, to further discourage use of these potentially harmful compounds, incorporation of SR9009 and SR9011 into screening methods is highly recommended.

In vitro metabolism study of a black market product containing SARM LGD-4033

Anabolic agents are often used by athletes to enhance their performance. However, use of steroids leads to considerable side effects. Non-steroidal selective androgen receptor modulators (SARMs) are a novel class of substances that have not been approved so far but seem to have a more favourable anabolic/androgenic ratio than steroids and produce fewer side effects. Therefore the use of SARMs has been prohibited since 2008 by the World Anti-Doping Agency (WADA). Several of these SARMs have been detected on the black market. Metabolism studies are essential to identify the best urinary markers to ensure effective control of emerging substances by doping control laboratories. As black market products often contain non-pharmaceutical-grade substances, alternatives for human excretion studies are needed to elucidate the metabolism. A black market product labelled to contain the SARM LGD-4033 was purchased over the Internet. Purity verification of the black market product led to the detection of LGD-4033, without other contaminants. Human liver microsomes and S9 liver fractions were used to perform phase I and phase II (glucuronidation) metabolism studies. The samples of the in vitro metabolism studies were analyzed by gas chromatography-(tandem) mass spectrometry (GC-MS(/MS)), liquid chromatography-high resolution-tandem mass spectrometry (LC-(HR)MS/MS). LC-HRMS product ion scans allowed to identify typical fragment ions for the parent compound and to further determine metabolite structures. In total five metabolites were detected, all modified in the pyrrolidine ring of LGD-4033. The metabolic modifications ranged from hydroxylation combined with keto-formation (M1) or cleavage of the pyrrolidine ring (M2), hydroxylation and methylation (M3/M4) and dihydroxylation (M5). The parent compound and M2 were also detected as glucuronide-conjugates. Copyright © 2016 John Wiley & Sons, Ltd.

Current trends in mass spectrometry of peptides and proteins: Application to veterinary and sports-doping control

Detection of misuse of peptides and proteins as growth promoters is a major issue for sport and food regulatory agencies. The limitations of current analytical detection strategies for this class of compounds, in combination with their efficacy in growth-promoting effects, make peptide and protein drugs highly susceptible to abuse by either athletes or farmers who seek for products to illicitly enhance muscle growth. Mass spectrometry (MS) for qualitative analysis of peptides and proteins is well-established, particularly due to tremendous efforts in the proteomics community. Similarly, due to advancements in targeted proteomic strategies and the rapid growth of protein-based biopharmaceuticals, MS for quantitative analysis of peptides and proteins is becoming more widely accepted. These continuous advances in MS instrumentation and MS-based methodologies offer enormous opportunities for detection and confirmation of peptides and proteins. Therefore, MS seems to be the method of choice to improve the qualitative and quantitative analysis of peptide and proteins with growth-promoting properties. This review aims to address the opportunities of MS for peptide and protein analysis in veterinary control and sports-doping control with a particular focus on detection of illicit growth promotion. An overview of potential peptide and protein targets, including their amino acid sequence characteristics and current MS-based detection strategies is, therefore, provided. Furthermore, improvements of current and new detection strategies with state-of-the-art MS instrumentation are discussed for qualitative and quantitative approaches.

Sensitive quantification of IGF-1 and its synthetic analogs in dried blood spots

Background: Dried blood spot sample collection could improve detection of the misuse of IGF-1, its analogs and growth hormone. An LC–MS/MS method was developed to measure two IGF-1 peptides and one analog peptide after trypsin digestion. In addition to standard method validation parameters, the effect of hematocrit on cysteine alkylation, trypsin digestion and the selection of internal standard were evaluated. Results: Quantification of IGF-1 peptides was possible with an LLOQ of 25 ng/ml and imprecision of less than 15%. Conclusion: While the effects of hematocrit must be evaluated empirically for each method, dried blood spots are a suitable matrix for the measurement of IGF-1 and its analogs by MS.

Biochemical markers of insulin-like growth factor-I misuse in athletes: the response of serum IGF-I, procollagen type III amino-terminal propeptide, and the GH-2000 score to the administration of rhIGF-I/rhIGF binding protein-3 complex

CONTEXT

The GH-2000 and GH-2004 research groups developed a method for detecting GH misuse in athletes based on the measurement of serum IGF-I and procollagen type III amino-terminal propeptide (P-III-NP). There are reports that IGF-I is also misused by athletes, but currently there is no internationally recognized test designed to detect recombinant human IGF-I misuse.

OBJECTIVE

The objective of the study was to examine the response of serum IGF-I, P-III-NP, and the GH-2000 score to recombinant human (rh) IGF-I/rhIGF binding protein-3 (IGFBP-3) administration in recreational athletes.

DESIGN AND SETTING

This was a randomized, double-blind, placebo-controlled rhIGF-I/rhIGFBP-3 administration study at Southampton General Hospital (Southampton, United Kingdom).

PARTICIPANTS

Fifty-six recreational athletes (26 women, 30 men) participated in the study.

INTERVENTION

Participants were randomized to treatment with low-dose (30 mg/d) or high-dose (60 mg/d) rhIGF-I/rhIGFBP-3 complex or placebo for 28 days. Blood was collected throughout the drug administration and washout periods. Serum IGF-I and P-III-NP were measured using commercial immunoassays and GH-2000 scores were calculated.

RESULTS

IGF-I, P-III-NP, and the GH-2000 score rose in response to both low- and high-dose rhIGF-I/rhIGFBP-3 administration. The relative maximum response of IGF-I (approximately 4-fold increase in women and men) was greater than that of P-III-NP (40%-50% increase in women, 35%-50% increase in men). The GH-2000 formulae, which incorporate IGF-I and P-III-NP results, detected up to 61% of women and 80% of men in the rhIGF-I/rhIGFBP-3 groups but, using IGF-I concentrations alone, the sensitivity increased to 94% in both women and men during the administration period.

CONCLUSIONS

The rise in P-III-NP after rhIGF-I/rhIGFBP-3 administration is small compared with that after rhGH administration. Although rhIGF-I/rhIGFBP-3 administration can be detected using the GH-2000 score method, a test based on serum IGF-I alone provides better sensitivity.

Determination of IGFs and their binding proteins

The worldwide clinical and scientific interest in peptides belonging to the insulin-like growth factor (IGF) system has brought along a call for standardization of assays used to quantify the different IGF related proteins. This relates in particular to the measurement of IGF-I, which has stood the test of time as an important biochemical tool in the diagnosis and treatment of growth hormone (GH) related disorders. The first international consensus statement on the measurement of IGF-I in 2011 represents an important milestone and will undoubtedly improve commutability of reference ranges for IGF-I and clinically applicable cut-off values. By contrast, there is no consensus addressing the measurements of the other IGF-related peptides. Nevertheless, measurement of these peptides may be of interest, either as additional tools in GH disorders or as prognostic biomarkers of various diseases. Therefore, standardization of assays for the other IGF-related peptides is highly relevant. This chapter discusses the recent consensus on IGF-I measurements and how this approach may be applied to measurement of the other IGF-related peptides. In addition, assay pitfalls, pre- and post-analytical challenges, alternative methods for IGF-I measurements and potential assays of tomorrow will be discussed.

Detection of human insulin-like growth factor-1 in deer antler velvet supplements

RATIONALE

Reported incidents of the use of nutritional supplements containing deer antler velvet by athletes has increased significantly in recent years. The supplements have been reported to contain insulin-like growth factor-1 (IGF-1), which is a banned substance included on the World Anti-Doping Agency (WADA) prohibited list. The presence of deer and human IGF-1 was tested in six commercially available supplements.

METHODS

IGF-1 was extracted from the six deer antler velvet supplements using chloroform and acetonitrile precipitation methods. Ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) methods were developed to measure intact IGF-1 protein and IGF-1 trypsin peptides using a triple quadrupole mass spectrometer. Five deer-specific and five human-specific multiple-reaction monitoring (MRM) transitions for intact IGF-1were measured as well as six deer-specific and seven human-specific MRM transitions for an IGF-1 trypsin peptide.

RESULTS

The peak area from each MRM transition was used to calculate the product ion ratios relative to the most abundant transition. Product ion ratios measured in the supplements were matched to ratios measured in purified protein standards. A match to human IGF-1 was identified for all the MRM transitions measured in four of the supplements tested.

CONCLUSIONS

The presence of a pharmaceutical protein, human IGF-1, was confirmed in four commercially available products sold as all natural, nutritional supplements. These methods can be used to screen additional products to further prevent the illegal sale of adulterated supplements.

Detection of erythropoiesis-stimulating agents in human anti-doping control: past, present and future

Stimulation of erythropoiesis is one of the most efficient ways of doping. This type of doping is advantageous for aerobic physical exercise and of particular interest to endurance athletes. Erythropoiesis, which takes place in bone marrow, is under the control of EPO, a hormone secreted primarily by the kidneys when the arterial oxygen tension decreases. In certain pathological disorders, such as chronic renal failure, the production of EPO is insufficient and results in anemia. The pharmaceutical industry has, thus, been very interested in developing drugs that stimulate erythropoiesis. With this aim, various strategies have been, and continue to be, envisaged, giving rise to an expanding range of drugs that are good candidates for doping. Anti-doping control has had to deal with this situation by developing appropriate methods for their detection. This article presents an overview of both the drugs and the corresponding methods of detection, and thus follows a roughly chronological order.

Growth hormone doping in sports: a critical review of use and detection strategies

GH is believed to be widely employed in sports as a performance-enhancing substance. Its use in athletic competition is banned by the World Anti-Doping Agency, and athletes are required to submit to testing for GH exposure. Detection of GH doping is challenging for several reasons including identity/similarity of exogenous to endogenous GH, short half-life, complex and fluctuating secretory dynamics of GH, and a very low urinary excretion rate. The detection test currently in use (GH isoform test) exploits the difference between recombinant GH (pure 22K-GH) and the heterogeneous nature of endogenous GH (several isoforms). Its main limitation is the short window of opportunity for detection (~12-24 h after the last GH dose). A second test to be implemented soon (the biomarker test) is based on stimulation of IGF-I and collagen III synthesis by GH. It has a longer window of opportunity (1-2 wk) but is less specific and presents a variety of technical challenges. GH doping in a larger sense also includes doping with GH secretagogues and IGF-I and its analogs. The scientific evidence for the ergogenicity of GH is weak, a fact that is not widely appreciated in athletic circles or by the general public. Also insufficiently appreciated is the risk of serious health consequences associated with high-dose, prolonged GH use. This review discusses the GH biology relevant to GH doping; the virtues and limitations of detection tests in blood, urine, and saliva; secretagogue efficacy; IGF-I doping; and information about the effectiveness of GH as a performance-enhancing agent.

Characterization and identification of a C-terminal amidated mechano growth factor (MGF) analogue in black market products

RATIONALE

Mechano growth factor (MGF) is a splice variant of insulin-like growth factor that possesses anabolic properties and has not yet been approved for therapeutic use. Nevertheless, it is readily available on the black market. Although the World Anti-Doping Agency (WADA) has banned the use of MGF in sports, no routinely performed methods have been reported for its detection. In this work, two preparations from the black market containing an unknown MGF analogue were characterized.

METHODS

Mass spectrometry characterizations of unknown preparations and a reference human MGF were performed on an Orbitrap and a triple quadrupole mass spectrometers after separation by liquid chromatography. High accuracy measurements allowed protein identification from full scan MS data, and low-resolution full scan MS/MS provided further information on fragmentation.

RESULTS

HCD scans of the analytes showed the presence of common b series product ions in the black market preparations and the human MGF reference standard, but all the y series ions starting from (y(1))(+) exhibited a difference of 1 m/z unit in nominal mass. This difference was demonstrated to be due to a C-terminal amidation of MGF. High-resolution data demonstrated that the black market products were both C-terminal amidated analogues of human MGF. In addition, low-resolution MS/MS characterization revealed a potentially diagnostic transition (m/z 717.8 → 431.1) for the discrimination of C-amidated MGF from the endogenous form.

CONCLUSIONS

Qualitative identification of a MGF C-terminal amidated analogue in two black market products was successfully achieved. This report demonstrates that illegal MGF preparations are commercially available for use as doping agent in sports.

Identification of fibroblast growth factor 1 (FGF-1) in a black market product

The use of growth factors for accelerated healing of sports injuries is restricted under the terms of the World Anti-Doping Agency (WADA) anti-doping code. Cheating athletes have used the black market as a source of performance-enhancing substances. Drugs that currently undergo clinical trials are frequently offered--despite the unknown health risks associated with the administration of unapproved pharmaceuticals. Recently, a new growth factor (referred to as fibroblast growth factor 1/FGF-1) with known effects on the repair and regeneration of damaged tissue was detected in an unlabelled black market product confiscated by the German customs. The identification of the protein was achieved by one- and two-dimensional polyacrylamide gel electrophoresis (SDS-PAGE and 2D-PAGE), different proteolytic digestions, immunological methods and nano-liquid chromatography high-resolution/high-accuracy Orbitrap mass spectrometry. The SDS-PAGE analysis revealed slight differences concerning the molecular weight of recombinant human and black market FGF-1. Using in-gel proteolysis, a truncation or modification located at the N-terminus of the protein was suggested. These findings demonstrate that drug candidates without clinical approval can be readily obtained from the black market, regardless of potential dangerous consequences for the consumer, which corroborates the necessity of proactive and preventive doping control approaches. In that regard, physiological concentrations of blood and urine specimens collected from healthy individuals were analyzed and were found to range below 28 pg/ml in urine, while there was no detectable FGF-1 in plasma.

OMICS-strategies and methods in the fight against doping

During the past decade OMICS-methods not only continued to have their impact on research strategies in life sciences and in particular molecular biology, but also started to be used for anti-doping control purposes. Research activities were mainly reasoned by the fact that several substances and methods, which were prohibited by the World Anti-Doping Agency (WADA), were or still are difficult to detect by direct methods. Transcriptomics, proteomics, and metabolomics in theory offer ideal platforms for the discovery of biomarkers for the indirect detection of the abuse of these substances and methods. Traditionally, the main focus of transcriptomics and proteomics projects has been on the prolonged detection of the misuse of human growth hormone (hGH), recombinant erythropoietin (rhEpo), and autologous blood transfusion. An additional benefit of the indirect or marker approach would also be that similarly acting substances might then be detected by a single method, without being forced to develop new direct detection methods for new but comparable prohibited substances (as has been the case, e.g. for the various forms of Epo analogs and biosimilars). While several non-OMICS-derived parameters for the indirect detection of doping are currently in use, for example the blood parameters of the hematological module of the athlete's biological passport, the outcome of most non-targeted OMICS-projects led to no direct application in routine doping control so far. The main reason is the inherent complexity of human transcriptomes, proteomes, and metabolomes and their inter-individual variability. The article reviews previous and recent research projects and their results and discusses future strategies for a more efficient application of OMICS-methods in doping control.