Detection of EPO doping and blood doping: the haematological module of the Athlete Biological Passport

New Transcriptomic Biomarkers for Detection of the Recombinant Human Erythropoietin (rHuEPO) MirCERA in Horses

Detection and monitoring of biomarkers related to doping is particularly suitable for the development of analytical strategies dedicated to indirect detection of banned substances. Previous studies in horses have already allowed the investigation of transcriptomic biomarkers in equine blood associated with reGH and rHuEPO administrations. Our most recent developments continue to focus on the discovery and monitoring of transcriptomic biomarkers for the control of ESAs, and a collaborative study with WADA-accredited doping control laboratories has recently been initiated to conduct a pilot study. In humans, three mRNAs (ALAS2, CA1, and SLC4A1) were previously observed to be differentially expressed after blood doping and were associated with immature red blood cells, the so-called circulating reticulocytes. In horses, circulating reticulocytes are rarely observed even after rHuEPO administration. With the improved primers that detect the equine orthologues of the human mRNAs from the ALAS2, CA1, and SLC4A1 genes, we can now report the first evidence of the detection of the three biomarkers in equine blood. In addition, an upregulation of the mRNA levels of the three genes was observed after analysis of blood samples collected from MirCERA-treated animals, with kinetics similar to those previously documented in humans. Our data suggest that ALAS2 and CA1 are promising indirect biomarkers for the detection of recombinant EPO abuse in horses, as observed in humans.

Comparison between standard hematological parameters and blood doping biomarkers in dried blood spots within the athlete population of Swiss Sport Integrity

Introduction

The study demonstrated the feasibility of incorporating RNA biomarkers, specifically 5-aminolevulinic acid synthase (ALAS2) and carbonic anhydrase 1 (CA1), to improve the hematological module of the Athlete Biological Passport (ABP) in routine antidoping context.

Objective

The aim was to investigate the implementation of reticulocyte (RET) related biomarkers, specifically ALAS2 and CA1, using quantitative reverse transcription polymerase chain reaction (RT-qPCR) on dried blood spots (DBS) from elite athletes. Hemoglobin changes over time in DBS samples was measured as well. Combining hemoglobin and messenger RNA (mRNA) analyses allowed to monitor alterations of the established marker, "DBS OFF-score".

Methodology

Ten athletes were selected for sampling by the Swiss national antidoping organization, Swiss Sports Integrity (SSI). Samples were collected, transported and analyzed for ABP following the World Anti-Doping Agency (WADA) procedures and spotted onto Protein Saver DBS cards.

Results

Most athletes exhibited stable biomarker levels, except for one individual involved in ski mountaineering, who demonstrated a sustained increase in ALAS2 compared to the individual baseline. This elevation could be due to blood withdrawal or other factors, such as doping with substances outside the targeted test menu.

Conclusion

In this study, RNA-biomarkers were successfully analyzed in routine blood samples, and the project demonstrated promising results for the implementation of ALAS2 and CA1 in routine analysis to complement the ABP.

Intelligence-based anti-doping via an Intelligence and Drug Testing Management (IDTM) system

The Intelligence and Drug Testing Management (IDTM), a system that can enhance drug testing analytics with related horse information and intelligence in a single platform, can help identify and mitigate potential doping and other threats.

Liquid vs dried blood matrices: Application to longitudinal monitoring of androstenedione, testosterone, and IGF-1 by LC-MS-based techniques

BACKGROUND

Dried blood spots have recently been approved by the World Anti-Doping Agency as an alternative biological matrix for testing of doping substances. However, their use is limited to the detection of non-threshold compounds without a Minimum Reporting Level due to the numerous issues related to quantitative analyses and the limitation on testing capabilities of a haemolysed matrix.

AIM

In this study androstenedione, testosterone and IGF-1 were longitudinally monitored in four different blood matrices to evaluate the potential of liquid capillary blood as an alternative matrix for quantitative determination in doping control analysis.

METHODOLOGY

The analytical protocols developed to pretreat 20 μL of the blood matrices selected were based: i) for testosterone and androstenedione, on supported liquid extraction for liquid blood matrices, and on ultrasonication in the presence of methanol for dried blood matrices; ii) for IGF-1, proteins precipitation followed by evaporation of the supernatant was used to pretreat both liquid and dried blood matrices. The detection for all the target analytes was performed using liquid chromatography coupled to mass spectrometry. The analytical workflows, once optimized, were fully validated according to the requirements of World Anti-Doping Agency and ISO 17025 standard and used for the analysis of venous (serum) and capillary (liquid plasma and dried whole blood collected using either volumetric or non-volumetric devices) blood samples collected from 7 healthy subjects.

RESULTS

The validation results showed satisfactory performance as related to specificity, sensitivity, matrix effects, linearity, accuracy, and precision in all the blood matrices evaluated despite the limited volume of sample used. The analysis of the different blood matrices collected from the subjects showed non-significant differences between the levels of testosterone and androstenedione measured in dried (fixed volume collected) and liquid matrices. An acceptable underestimation (lower than 15 %) was observed in capillary plasma compared to venous serum. The testosterone/androstenedione ratio was similar in all the blood matrices considered (bias lower than 5 %), indicating this parameter was not affected by either the blood matrix or collection device selected. For IGF-1, the levels measured in liquid blood matrices differed significantly (bias higher than 20 %) from those measured in dried whole blood matrices, suggesting haemolyzed blood might represent a challenge for the determination of macromolecules, mainly due to the complexity of the whole blood matrix in comparison to plasma/serum.

NOVELTY

The outcomes of our study suggest that liquid capillary blood might open new avenues to blood microsampling in doping control field. It represents an efficient alternative to overcome the issues related to venous blood and dried blood spot sampling. Furthermore, it also allows greater frequency of blood sampling, with minor discomfort and without needing a phlebotomist, for analyses that can only be performed in blood samples, with an increased probability to detect and report Adverse Analytical Finding.

Use of RNA biomarkers in the antidoping field

There is growing evidence that various RNA molecules can serve as biomarkers for clinical diagnoses. Over the last decade, the high specificities and sensitivities of RNA biomarkers have led to proposals that they could be used to detect prohibited substances and practices in sports. mRNAs and circulating miRNAs have the potential to improve the detection of doping and expand the performance of the Athlete Biological Passport. This review provides a summary of the use of RNA biomarkers to detect human and equine doping practices, including a discussion of the use of dried blood spots as a stable matrix that supports and improves the general process of RNA biomarker detection. The advantages of RNA biomarkers over protein biomarkers are also discussed.

Performance-enhancing substances in sport: A scientometric review of 75 years of research

The use of performance-enhancing substances not only undermines the core values of sports but also poses significant health risks to athletes. In a fast-evolving doping environment, where sport professionals are constantly seeking novel and illegal means to bypass doping tests, and new substances are regularly detected on the drug market, it is crucial to inform authorities with updated evidence emerging from scientific research. The current study aims to (i) outline the structure of knowledge in the literature on performance enhancers in sports (i.e., most active countries, main sources, most productive authors, and most frequently used keywords); (ii) identify the most impactful documents in the field; and (iii) uncover the main domains of research in the literature. To do so, we conducted a comprehensive scientometric analysis of the literature on doping, sourcing our data from Scopus. Our research involved a document co-citation analysis of 193,076 references, leading to the identification of the 51 most influential documents and seven key thematic areas within the doping literature. Our results indicate that the scientific community has extensively studied the most prevalent doping classes, such as anabolic agents and peptide hormones, and little is still known about the use of contaminated supplements or other types of enhancers identified as emergent trends. Concurrently, technological advancements contributed to the development of more sophisticated doping detection techniques, using blood or urine samples. More recently, the focus has shifted towards the athlete biological passport, with research efforts aimed at identifying biomarkers indicative of doping. The dynamic nature of doping methods underlines the necessity for more robust educational campaigns, aiming at raising awareness among sports professionals and their entourage about the dangers of doping and the intricacies of its control mechanisms.

Homologous blood transfusion and doping: Where are we now?

Homologous blood transfusion (HBT) is used for doping in endurance sports since the 1960s. The blood comes from a compatible donor, that is, someone with a compatible ABO and rhesus blood group. Despite been prohibited by the IOC in 1985, no detection method was available until 2003. Then came the idea to use red blood cells (RBC) minor blood groups antigens that constitute an "identity" card of someone's RBC to detect the presence of a second RBC population. The method validated for doping control samples uses flow cytometry after incubation of isolated RBC with eight to 12 primary antibodies against specific minor blood groups antigens. The presence of double populations of RBC is revealed by a major and a minor peak in a fluorescence histogram. The sensitivity was estimated sufficient to detect HBT for a few weeks. Despite the complexity and cost of the method, right after its application in 2004, several cases of HBT were identified but the number of cases dropped rapidly over the years. In the 2010s, other ways to detect HBT were developed and evaluated: indirect detection using the Athlete Biological Passport approach, and a few years later forensic DNA analysis to establish the presence of two different DNA in a blood sample after HBT. Despite the high specificity of the latter, the sensitivity was recently questioned in vivo. Nowadays, the flow cytometry method remains the method of choice for HBT detection and recent investigations helped to simplify the method and increase its specificity and sensitivity.

mRNA biomarkers sensitive and specific to micro-dose erythropoietin treatment at sea level and altitude

Recombinant human erythropoietin (rhEPO) is prohibited by the World Anti-Doping Agency. rhEPO abuse can be indirectly detected via the athlete biological passport (ABP). However, altitude exposure challenges interpretation of the ABP. This study investigated whether 5'-aminolevulinate synthase 2 (ALAS2) and carbonic anhydrase 1 (CA1) in capillary dried blood spots (DBSs) are sensitive and specific markers of rhEPO treatment at altitude. ALAS2 and CA1 expression was monitored in DBS collected weekly before, during, and after a 3-week period at sea level or altitude. Participants were randomly assigned to receive 20 IU kg bw-1 epoetin alpha (rhEPO) or placebo injections every second day for 3 weeks while staying at sea level (rhEPO, n = 25; placebo, n = 9) or altitude (rhEPO, n = 12; placebo, n = 27). ALAS2 and CA1 expression increased up to 300% and 200%, respectively, upon rhEPO treatment at sea-level and altitude (P-values <0.05). When a blinded investigator interpreted the results, ALAS2 and CA1 expression had a sensitivity of 92%. Altitude did not confound the interpretation. Altitude affected ALAS2 and CA1 expression less than actual ABP markers when compared between sea level and altitude results. An individual athlete passport-like approach simulation confirmed the biomarker potential of ALAS2 and CA1. ALAS2 and CA1 were sensitive and specific biomarkers of micro-dose rhEPO treatment at sea level and altitude. Altitude seemed less a confounding factor for these biomarkers, especially when they are combined. Thus, micro-dose rhEPO injections can be detected in a longitudinal blinded setting using mRNA biomarkers in DBS.

Impact of low-volume blood withdrawal on hematological biomarkers for the athlete biological passport

This study investigated the impact of low-volume blood withdrawal on the hematological biomarkers currently considered for anti-doping purposes. After baseline measurement (D - 7), a 140 mL blood withdrawal was completed (D + 0) on 12 healthy volunteers, followed by weekly monitoring for 21 days (D + 7 - 21). Each visit consisted of a full blood count (Sysmex XN-1000) and duplicate blood volume measurements by CO-rebreathing. A significant decrease in total hemoglobin mass (Hbmass) (-2.3%, p = 0.007) and red blood cell volume (RBCV) (-2.8%, p = 0.028) was reported at D + 7. Despite no atypical passport finding (ATPF) when considering the athlete biological passport adaptive longitudinal model, hemoglobin concentration ([Hb]) increased significantly at D + 21 (+3.8%, p = 0.031). Besides, ferritin (FERR) was significantly downregulated at all points following blood withdrawal, with the largest decrease occurring at D + 7 (-26.6%, p < 0.001). Regardless of the presumable effect of blood reinfusion on ABP biomarkers, these results illustrate the challenge of monitoring hematological variables for the detection of low-volume blood withdrawal. Finally, this study outlines the sensitivity of FERR to altered erythropoiesis to support the implementation of iron markers as complementary variables for the longitudinal monitoring of blood doping, despite the potential influence of confounding factors (e.g., iron supplementations).

Indirect biomarkers of blood doping: A systematic review

The detection of blood doping represents a current major issue in sports and an ongoing challenge for antidoping research. Initially focusing on direct detection methods to identify a banned substance or its metabolites, the antidoping effort has been progressively complemented by indirect approaches. The longitudinal and individual monitoring of specific biomarkers aims to identify nonphysiological variations that may be related to doping practices. From this perspective, the identification of markers sensitive to erythropoiesis alteration is key in the screening of blood doping. The current Athlete Biological Passport implemented since 2009 is composed of 14 variables (including two primary markers, i.e., hemoglobin concentration and OFF score) for the hematological module to be used for indirect detection of blood doping. Nevertheless, research has continually proposed and investigated new markers sensitive to an alteration of the erythropoietic cascade and specific to blood doping. If multiple early markers have been identified (at the transcriptomic level) or developed directly in a diagnostics' kit (at a proteomic level), other target variables at the end of the erythropoietic process (linked with the red blood cell functions) may strengthen the hematological module in the future. Therefore, this review aims to provide a global systematic overview of the biomarkers considered to date in the indirect investigation of blood doping.

Hematologic setpoints are a stable and patient-specific deep phenotype

The complete blood count is an important screening tool for healthy adults and is the most commonly ordered test at periodic physical exams. However, results are usually interpreted relative to one-size-fits-all reference intervals, undermining the goal of precision medicine to tailor medical care to the needs of individual patients based on their unique characteristics. Here we show that standard complete blood count indices in healthy adults have robust homeostatic setpoints that are patient-specific and stable, with the typical healthy adult's set of 9 blood count setpoints distinguishable from 98% of others, and with these differences persisting for decades. These setpoints reflect a deep physiologic phenotype, enabling improved detection of both acquired and genetic determinants of hematologic regulation, including discovery of multiple novel loci via GWAS analyses. Patient-specific reference intervals derived from setpoints enable more accurate personalized risk assessment, and the setpoints themselves are significantly correlated with mortality risk, providing new opportunities to enhance patient-specific screening and early intervention. This study shows complete blood count setpoints are sufficiently stable and patient-specific to help realize the promise of precision medicine for healthy adults.

Doping and sports endocrinology: growth hormone, IGF-1, insulin, and erythropoietin

Among the substances prohibited by the World Anti-Doping Agency, "peptide hormones, growth factors, related substances, and mimetics" are classified as prohibited both in- and out-of-competition in section S2. This work reviews growth hormone and its releasing peptides, insulin-like growth factor 1 as the main growth factor, insulin, and erythropoietin and other agents that affect erythropoiesis. This review analyzes the prevalence of use among professional athletes and gym clients, the forms of use, dosing, ergogenic effects and effects on physical performance, as well as side effects and anti-doping detection methods.

Red blood cell derived extracellular vesicles during the process of autologous blood doping

The purpose of this pilot study was to investigate the effects of the transfusion of one erythrocyte concentrate on the number of circulating red blood cell extracellular vesicles (RBC-EVs) and their clearance time. Six, healthy volunteers donated their blood and were transfused with their RBC concentrate after 35-36 days of storage. One K₂ EDTA and one serum sample were collected before donation, at four timepoints after donation and at another six timepoints after transfusion. RBC-EVs were analyzed on a Cytek Aurora flow cytometer. A highly significant increase (p < 0.001) of RBC-EVs from an average of 60.1 ± 19.8 (10³ /μL) at baseline to 179.3 ± 84.7 (10³ /μL) in the first 1-3 h after transfusion could be observed. Individual differences in the response to transfusion became apparent with one volunteer showing no increase and another an increased concentration at one timepoint after donation due to an influenza infection. We concluded that in an individualized passport approach, increased RBC-EVs might be considered as additional evidence when interpreting suspicious Athletes Biological Passport (ABPs) but for this additional research related to sample collection and transport processes as well as method development and harmonization would be necessary.

Altitude and Erythropoietin: Comparative Evaluation of Their Impact on Key Parameters of the Athlete Biological Passport: A Review

The hematological module of the Athlete's Biological Passport (ABP) identifies doping methods and/or substances used to increase the blood's capacity to transport or deliver oxygen to the tissues. Recombinant human erythropoietin (rhEPOs) are doping substances known to boost the production of red blood cells and might have an effect on the blood biomarkers of the ABP. However, hypoxic exposure influences these biomarkers similarly to rhEPOs. This analogous impact complicates the ABP profiles' interpretation by antidoping experts. The present study aimed to collect and identify, through a literature search, the physiological effects on ABP blood biomarkers induced by these external factors. A total of 43 studies were selected for this review. A positive correlation (R² = 0.605, r = 0.778, p < 0.001) was identified between the hypoxic dose and the increase in hemoglobin concentration (HGB) percentage. In addition, the change in the reticulocyte percentage (RET%) has been identified as one of the most sensitive parameters to rhEPO use. The mean effects of rhEPO on blood parameters were greater than those induced by hypoxic exposure (1.7 times higher for HGB and RET% and 4 times higher for hemoglobin mass). However, rhEPO micro-doses have shown effects that are hardly distinguishable from those identified after hypoxic exposure. The results of the literature search allowed to identify temporal and quantitative evolution of blood parameters in connection with different hypoxic exposure doses, as well as different rhEPOs doses. This might be considered to provide justified and well-documented interpretations of physiological changes in blood parameters of the Athlete Biological Passport.

Removal of the influence of plasma volume fluctuations for the athlete biological passport and stability of haematological variables in active women taking oral contraception

The haematological module of the athlete biological passport (ABP) monitors longitudinal haematological variations that could be indicative of blood manipulation. This study applied a multi‐parametric model previously validated in elite cyclists to compare inferred and actual PV variations, whereas the potential influence of the oral contraceptive pill (OCP) cycle on the ABP blood biomarkers and plasma volume (PV) in 14 physically active women taking OCPs was also investigated. Blood and serum samples were collected each week for 8 weeks, and the ABP haematological variables were determined according to the World Anti‐Doping Agency guidelines. Transferrin (sTFN), ferritin (FERR), albumin (ALB), calcium (Ca), creatinine (CRE), total protein (TP) and low‐density lipoprotein (LDL) were additionally computed as ‘volume‐sensitive’ variables in a multivariate analysis to determine individual estimations of PV variations. Actual PV variations were indirectly measured using a validated carbon monoxide rebreathing method. We hypothesised ABP markers to be stable during a standard OCP cycle and estimated PV variations similar to measured PV variations. Measured PV variations were in good agreement with the predictions and allowed to explain an atypical passport finding (ATPF). The ABP biomarkers, Hbmass and PV were stable over 8 weeks. Significant differences occurred only between Week 7 and Week 1, with lower levels of haemoglobin concentration ([Hb]), haematocrit (HCT) and red blood cell count (RBC)(−4.4%, p < 0.01; −5.1%, p < 0.01; −5.2%, p < 0.01) and higher levels of PV at week 7 (+9%, p = 0.05). We thus concluded that estimating PV variations may help interpret individual ABP haematological profiles in women.

Measurement of Immature Reticulocytes in Dried Blood Spots by Mass Spectrometry

BACKGROUND

Immature reticulocytes (IRC) are the first cells to respond to changes in erythropoiesis. For antidoping applications, measurement of IRC may improve detection of blood doping practices. Unfortunately, this small cell population has limited stability in liquid blood samples and is difficult to measure with optimal precision. We developed a method to measure 3 IRC membrane proteins in dried blood spots (DBS) to monitor changes in erythropoiesis.

METHODS

DBS spots were washed with buffers to remove soluble proteins, membrane proteins remaining in the spot were digested with trypsin, and one peptide for each protein was measured by LC-MS/MS. IRC protein concentration was determined using a DBS single point calibrator.

RESULTS

Intraassay precision for IRC proteins was between 5%-15%. IRC proteins were stable in DBS for 29 days at room temperature. In a longitudinal study of 25 volunteers, the mean intraindividual variation for 3 IRC proteins was 17%, 20%, and 24% from capillary blood DBS. In comparison, the mean longitudinal variation for IRC counts measured on an automated hematology analyzer was 38%. IRC protein concentration from capillary blood DBS correlated well with venous blood DBS protein concentrations.

CONCLUSIONS

Measurement of IRC proteins in DBS samples provides a method to measure changes in erythropoiesis with improved analytical sensitivity, stability, and precision. When combined with the inherent advantages of capillary blood collection in the field, this method may substantially improve the detection of blood doping practices.

Immature reticulocytes are sensitive and specific to low-dose erythropoietin treatment at sea level and altitude

We investigated whether immature reticulocyte fraction (IRF) and immature reticulocytes to red blood cells ratio (IR/RBC) are sensitive biomarkers for low-dose recombinant human erythropoietin (rhEpo) treatment at sea level (SL) and moderate altitude (AL) and whether multi (FACS) or single (Sysmex-XN) fluorescence flow cytometry is superior for IRF and IR/RBC determination. Thirty-nine participants completed two interventions, each containing a 4-week baseline, a 4-week SL or AL (2,230 m) exposure, and a 4-week follow-up. During exposure, rhEpo (20 IU kg^-1 ) or placebo (PLA) was injected at SL (SL_rhEpo , n = 25, SL_PLA n = 9) and AL (AL_rhEpo , n = 12, AL_PLA n = 27) every second day for 3 weeks. Venous blood was collected weekly. Sysmex measurements revealed that IRF and IR/RBC were up to ~70% (P < 0.01) and ~190% (P < 0.001) higher in SL_rhEpo than SL_PLA during treatment and up to ~45% (P < 0.001) and ~55% (P < 0.01) lower post-treatment, respectively. Compared with AL_PLA , IRF and IR/RBC were up to ~20% (P < 0.05) and ~45% (P < 0.001) lower post-treatment in SL_rhEpo , respectively. In AL_rhEpo , IRF and IR/RBC were up to ~40% (P < 0.05) and ~110% (P < 0.001) higher during treatment and up to ~25% (P < 0.05) and ~40% (P < 0.05) lower post-treatment, respectively, compared with AL_PLA . Calculated thresholds provided ~90% sensitivity for both biomarkers at SL and 33% (IRF) and 66% (IR/RBC) at AL. Specificity was >99%. Single-fluorescence flow cytometry coefficient of variation was >twofold higher at baseline (P < 0.001) and provided larger or similar changes compared to multi-fluorescence, albeit with smaller precision. In conclusion, IRF and IR/RBC were sensitive and specific biomarkers for low-dose rhEpo misuse at SL and AL.

Erythroferrone structure, function, and physiology: Iron homeostasis and beyond

Erythroferrone (ERFE) is the main erythroid regulator of hepcidin, the homeostatic hormone controlling plasma iron levels and total body iron. When the release of erythropoietin from the kidney stimulates the production of new red blood cells, it also increases the synthesis of ERFE in bone marrow erythroblasts. Increased ERFE then suppresses hepcidin synthesis, thereby mobilizing cellular iron stores for use in heme and hemoglobin synthesis. Recent mechanistic studies have shown that ERFE suppresses hepcidin transcription by inhibiting bone morphogenetic protein signaling in hepatocytes. In ineffective erythropoiesis, pathological overproduction of ERFE by an expanded population of erythroblasts suppresses hepcidin and causes iron overload, even in non-transfused patients. ERFE may be a useful biomarker of ineffective erythropoiesis and an attractive target for treating its systemic effects.

The Influence of Floorball on Hematological Parameters: Consequences in Health Assessment and Antidoping Testing

Assessment of hematological parameters is common in sports medicine. Although physical exercise is an important preanalytical variable, data about acute hematological changes after high-intensity intermittent exercise are scarce. This study aimed to examine floorball as a potential preanalytical variable for hematological parameters used in health assessment and antidoping testing. Twenty-three professional male floorball players participated in a floorball game. Hematological parameters including hemoglobin, erythrocyte count and erythrocyte indices, reticulocytes, white blood cells (WBC), platelets, reticulocytes, and OFF-hr score were assessed at baseline, immediately postgame, and at 2 h postgame. Median hemoglobin concentration decreased significantly from 146 g/L pregame to 141 g/L immediately postgame (p < 0.001). WBC count increased from 7.2 × 10⁹/L pregame to 10.1 × 10⁹/L 2 h postgame (p < 0.001). The median OFF-hr score decreased from 99.5 to 94.2 immediately postgame and remained significantly lower than baseline at 2 h postgame (94.4, p=0.030). Looking at individual results, the highest OFF-hr score increased from 120 at baseline to 124 at 2 h postgame. Our findings suggest that participation in a floorball game affects several hematological parameters and consequently can affect health assessment and antidoping testing.

Prevalence Estimate of Blood Doping in Elite Track and Field Athletes During Two Major International Events

In elite sport, the Athlete Biological Passport (ABP) was invented to tackle cheaters by monitoring closely changes in biological parameters, flagging atypical variations. The hematological module of the ABP was indeed adopted in 2011 by World Athletics (WA). This study estimates the prevalence of blood doping based on hematological parameters in a large cohort of track and field athletes measured at two international major events (2011 and 2013 WA World Championships) with a hypothesized decrease in prevalence due to the ABP introduction. A total of 3683 blood samples were collected and analyzed from all participating athletes originating from 209 countries. The estimate of doping prevalence was obtained by using a Bayesian network with seven variables, as well as "blood doping" as a variable mimicking doping with low-doses of recombinant human erythropoietin (rhEPO), to generate reference cumulative distribution functions (CDFs) for the Abnormal Blood Profile Score (ABPS) from the ABP. Our results from robust hematological parameters indicate an estimation of an overall blood doping prevalence of 18% in 2011 and 15% in 2013 (non-significant difference) in average in endurance athletes [95% Confidence Interval (CI) 14-22 and 12-19% for 2011 and 2013, respectively]. A higher prevalence was observed in female athletes (22%, CI 16-28%) than in male athletes (15%, CI 9-20%) in 2011. In conclusion, this study presents the first comparison of blood doping prevalence in elite athletes based on biological measurements from major international events that may help scientists and experts to use the ABP in a more efficient and deterrent way.

Athlete Biological Passport: Need and Challenges

The Athlete Biological Passport programme was initiated in 2009 by the World Anti-Doping Agency for making the anti-doping programme more effective and stronger. There are three modules in this ABP programme: haematological, steroidal and endocrinological. Currently, the first two modules have been implemented. The newer products such as recombinant human erythropoietin, recombinant proteins, and peptides are similar to those produced naturally. Hence, detection of these substances even with advanced techniques is difficult. Therefore, the concept of ABP came into existence which is based on longitudinal monitoring of biological markers and their variations over a period of time. The ABP does not rely upon the detection of a particular prohibited substance but it reflects the changes in biological markers collated over an athlete's career. Hence, athletes can be monitored through constant interpretation of the passport data. There are many advantages with the implementation of this programme; however, there are various issues which may lead to false interpretation of passport data that must be taken into consideration.

Fighting Doping in Elite Sports: Blood for All Tests!

In the fight against doping, detection of doping substances in biological matrices is paramount. Analytical possibilities have evolved and sanctioning a doping scenario by detecting forbidden bioactive compounds circulating unmodified in blood is nowadays very attractive. In addition, the World Anti-Doping Agency (WADA) introduced the Athlete Biological Passport (ABP) a decade ago as a new paradigm inferring the use of prohibited substances or methods through longitudinal profiling, or serial analyses of indirect biomarkers of doping, to be both scientifically and legally robust. After the introduction in 2008 of an hematological module (i.e., based on variations of blood variables) aiming to identify enhancement of oxygen transport and any form of blood transfusion or manipulation, a urinary steroidal module was additionally introduced in 2014 composed of concentrations and ratios of various endogenously produced steroidal hormones. Some evidence tends to discredit steroid profiles obtained from urine analyses to detect the use of endogenous androgenic anabolic steroids (EAAS), when administered exogenously, due to high rates of false negatives with short half-life and topical formulations rendering profile alteration only minimal or equivocal. On the other hand, steroid hormones quantification in blood showed a promising ability to detect testosterone doping and interesting complementarities to the ABP thanks to the most recent analytical techniques (UHPLC-HRMS or/and MS/MS). This perspective article explores the opportunities of blood samples to monitor not only hematological but also steroid profiles in elite athletes.

Altered erythroid-related miRNA levels as a possible novel biomarker for detection of autologous blood transfusion misuse in sport

BACKGROUND

Autologous blood transfusion (ABT) is a performance-enhancing method prohibited in sport; its detection is a key issue in the field of anti-doping. Among novel markers enabling ABT detection, microRNAs (miRNAs) might be considered a promising analytical tool.

STUDY DESIGN AND METHODS

We studied the changes of erythroid-related microRNAs following ABT, to identify novel biomarkers. Fifteen healthy trained males were studied from a population of 24 subjects, enrolled and randomized into a Transfusion (T) and a Control (C) group. Seriated blood samples were obtained in the T group before and after the two ABT procedures (withdrawal, with blood refrigerated or cryopreserved, and reinfusion), and in the C group at the same time points. Traditional hematological parameters were assessed. Samples were tested by microarray analysis of a pre-identified set of erythroid-related miRNAs.

RESULTS

Hematological parameters showed moderate changes only in the T group, particularly following blood withdrawal. Among erythroid-related miRNAs tested, following ABT a pool of 7 miRNAs associated with fetal hemoglobin and regulating transcriptional repressors of gamma-globin gene was found stable in C and differently expressed in three out of six T subjects in the completed phase of ABT, independently from blood conservation. Particularly, two or more erythropoiesis-related miRNAs within the shortlist constituted of miR-126-3p, miR-144-3p, miR-191-3p, miR-197-3p, miR-486-3p, miR-486-5p, and miR-92a-3p were significantly upregulated in T subjects after reinfusion, with a person-to-person variability but with congruent changes.

CONCLUSIONS

This study describes a signature of potential interest for ABT detection in sports, based on the analysis of miRNAs associated with erythroid features.

Altitude Training and Recombinant Human Erythropoietin: Considerations for Doping Detection

The benefit of training at altitude to enhance exercise performance remains equivocal although the most widely accepted approach is one where the athletes live and perform lower-intensity running at approximately 2300 m with high-intensity training at approximately 1250 m. The idea is that this method maintains maximal augmentations in total hemoglobin mass while reducing the performance impairment of high-intensity sessions performed at moderate altitude and thus preventing any detraining that can occur when athletes live and train at moderate altitude. This training regimen, however, is not universally accepted and some argue that the performance enhancement is due to placebo and training camp effects. Altitude training may affect an athlete's hematological parameters in ways similar to those observed following blood doping. Current methods of detection appear insufficient to differentiate between altitude training and blood doping making the interpretation of an athlete's biological passport difficult. Further research is required to determine the optimal method for altitude training and to enhance current detection methods to be able to differentiate better blood doping and altitude exposure.

Assessing serum albumin concentration following exercise-induced fluid shifts in the context of the athlete biological passport

PURPOSE

The hydration status of an athlete at the time of a doping control sample collection is an important factor to consider when reviewing athlete biological passports (ABPs). Dehydration results in a reduction of the circulating plasma volume (PV), which may lead to artificially high values of some blood parameters. This study aimed to identify whether serum albumin could serve as a single marker of fluid shifts, which are not currently accounted for in the hematological passport. An additional marker could be used to assist experts when interpreting irregularities in the ABP.

METHODS

Twelve subjects underwent multiple controlled exercise trials designed to induce varying levels of PV shifts. Pre-exercise blood samples were collected to establish baseline values for individual passports. During exercise interventions, blood samples were collected before the start of exercise and at 10 minute, 1 hour, 2 hours, and 24 hours following exercise.

RESULTS

Significant increases in hematological parameters - hemoglobin [Hb], hematocrit (HCT), albumin (ALB), and calculated OFF-score - were identified at varying time points following fluid shift-inducing exercise. Changes in ALB correlated strongly with changes in [Hb] (r = 0.753) and with estimated PV shifts (r = -0.764). In analyzing ABPs, the resulting increases in Hb did not trigger any atypical findings at 99% specificity.

PERSPECTIVE

Monitoring changes in ALB longitudinally may assist experts when reviewing PV shifts in the biological passport.

Changes in hemoglobin profile reflect autologous blood transfusion misuse in sports

The changes in hemoglobin (Hb) profile following autologous blood transfusion (ABT) for the first time were studied for anti-doping purposes. Twenty-four healthy, trained male subjects (aged 18‒40) were enrolled and randomized into either the transfusion (T) or control (C) groups. Blood samples were taken from the T subjects at baseline, after withdrawal and reinfusion of 450 ml of refrigerated or cryopreserved blood, and from C subjects at the same time points. Hematological variables (Complete blood count, Reticulocytes, Immature Reticulocytes Fraction, Red-cell Distribution Width, OFF-hr score) were measured. The Hb types were analyzed by high-performance liquid chromatography and the Hemoglobin Profile Index (HbPI) arbitrarily calculated. Between-group differences were observed for red blood cells and reticulocytes. Unlike C, the T group, after withdrawal and reinfusion, showed a significant trend analysis for both hematological variables (Hemoglobin concentration, reticulocytes, OFF-hr score) and Hb types (glycated hemoglobin-HbA1c, HbPI). The control charts highlighted samples with abnormal values (> 3-SD above/below the population mean) after reinfusion for hematological variables in one subject versus five subjects for HbA1c and HbPI. A significant ROC-curve analysis (area = 0.649, p = 0.015) identified a HbA1c cut-off value ≤ 2.7% associated to 100% specificity of blood reinfusion (sensitivity 25%). Hemoglobin profile changed in trained subjects after ABT, with abnormal values of HbA1c and HbPI in 42% of subjects after reinfusion. Future studies will confirm the usefulness of these biomarkers in the anti-doping field.

Do athletes have a right to access data in their Athlete Biological Passport?

The Athlete Biological Passport (ABP) refers to the collection of data related to an individual athlete. The ABP contains the Haematological Module and the Steroidal Module, which are used for the longitudinal monitoring of variables in blood and urine, respectively. Based on changes in these variables, a statistical model detects outliers which indicate doping use and guide further targeted testing of the athlete. Presently, athletes can access their data of the Haematological Module in the Anti-Doping Administration and Management System (ADAMS). However, granting athletes access to this data has been a matter of debate within the anti-doping community. This article investigates whether an athlete has a right to access the contents of their ABP profile. We approached this discussion by comparing the nature of ABP data with that of forensic and medical data and touched on important concerns with ABP data disclosure to athletes such as potentially allowing for the development of alternative doping techniques to circumvent detection; and making athletes vulnerable to pressure by the media to publicly release their data. Furthermore, given that ABP data may contain medically relevant information that can be used to diagnose disease, athletes may over-interpret its medical significance and wrongly see it as a free health check. We argue that safeguarding the integrity of the ABP system must be seen as the most essential element and thus a departure from immediate data disclosure is necessary. Two different strategies for delayed data disclosure are proposed which diminish the chances of ABP data being misused to refine doping techniques.

Influence of combined iron supplementation and simulated hypoxia on the haematological module of the athlete biological passport

The integrity of the athlete biological passport (ABP) is underpinned by understanding normal fluctuations of its biomarkers to environmental or medical conditions, for example, altitude training or iron deficiency. The combined impact of altitude and iron supplementation on the ABP was evaluated in endurance-trained athletes (n = 34) undertaking 3 weeks of simulated live-high: train-low (14 h.d^-1 , 3000 m). Athletes received either oral, intravenous (IV) or placebo iron supplementation, commencing 2 weeks prior and continuing throughout hypoxic exposure. Venous blood was sampled twice prior, weekly during, and up to 6 weeks after altitude. Individual ABP thresholds for haemoglobin concentration ([Hb]), reticulocyte percentage (%retic), and OFF score were calculated using the adaptive model and assessed at 99% and 99.9% specificity. Eleven athletes returned values outside of the calculated reference ranges at 99%, with 8 at 99.9%. The percentage of athletes exceeding the thresholds in each group was similar, but IV returned the most individual occurrences. A similar frequency of abnormalities occurred across the 3 biomarkers, with abnormal [Hb] and OFF score values arising mainly during-, and %retic values mainly post- altitude. Removing samples collected during altitude from the model resulted in 10 athletes returning abnormal values at 99% specificity, 2 of whom had not triggered the model previously. In summary, the abnormalities observed in response to iron supplementation and hypoxia were not systematic and mostly in line with expected physiological adaptations. They do not represent a uniform weakness in the ABP. Nevertheless, altitude training and iron supplementation should be carefully considered by experts evaluating abnormal ABP profiles.

Extracellular microRNA signature in chronic kidney disease

MicroRNAs (miRNAs) are noncoding RNAs that regulate posttranscriptional gene expression. In this study we characterized the circulating and urinary miRNA pattern associated with reduced glomerular filtration rate, using Affymetrix GeneChip miR 4.0 in 28 patients with chronic kidney disease (CKD). Top miRNA discoveries from the human studies were validated in an Alb/TGFβ mouse model of CKD, and in rat renal proximal tubular cells (NRK52E) exposed to TGFβ1. Plasma and urinary levels of procollagen III N-terminal propeptide and collagen IV were elevated in patients with decreased estimated glomerular filtration rate (eGFR). Expression of 384 urinary and 266 circulatory miRNAs were significantly different between CKD patients with eGFR ≥30 vs. <30 ml·min^-1·1.73 m^-2 Pathway analysis mapped multiple miRNAs to TGFβ signaling-related mRNA targets. Specifically, Let-7a was significantly downregulated, and miR-130a was significantly upregulated, in urine of patients with eGFR <30; miR-1825 and miR-1281 were upregulated in both urine and plasma of patients with decreased eGFR; and miR-423 was significantly downregulated in plasma of patients with decreased eGFR. miRNA expression in urine and plasma of Alb/TGFβ mice generally resembled and confirmed most, although not all, of the observations from the human studies. In response to TGFβ1 exposure, rat renal proximal tubular cells overexpressed miR-1825 and downregulated miR-423. Thus, miRNA are associated with kidney fibrosis, and specific urinary and plasma miRNA profile may have diagnostic and prognostic utility in CKD.

Hepcidin as a potential biomarker for blood doping

The concentration of hepcidin, a key regulator of iron metabolism, is suppressed during periods of increased erythropoietic activity. The present study obtained blood samples from 109 elite athletes and examined the correlations between hepcidin and markers of erythropoiesis and iron metabolism (i.e., haemoglobin, erythropoietin (EPO), ferritin, erythroferrone (ERFE), and iron concentration). Furthermore, an administration study was undertaken to examine the effect of recombinant human EPO (rhEPO) delta (Dynepo™) on hepcidin concentrations in healthy male volunteers. The effects on hepcidin were then compared with those on reticulocyte percentage (Ret%) and ferritin concentration. There was a significant positive correlation between hepcidin and ferritin, iron, and haemoglobin levels in athletes, whereas hepcidin showed an inverse correlation with ERFE. Administration of rhEPO delta reduced hepcidin levels, suggesting that monitoring hepcidin may increase the sensitivity of the Athlete Biological Passport (ABP) for detecting rhEPO abuse. Copyright © 2016 John Wiley & Sons, Ltd.

Circulating microRNAs: The Future of Biomarkers in Anti-doping Field

microRNAs (miRNAs) are small non-coding RNAs that regulate various biological processes. Cell-free miRNAs have been proposed as biomarkers of disease, including diagnosis, prognosis, and monitoring of treatment responses. These circulating miRNAs are highly stable in several body fluids, including plasma and serum; hence, in view of their potential use as novel, non-invasive biomarkers, the profiles of circulating miRNAs have been explored in the field of anti-doping. This chapter describes the enormous potential of circulating miRNAs as a new class of biomarkers for the detection of doping substances, and highlights the advantages of measuring these stable species over other methods that have already been implemented in anti-doping regimes. Incorporating longitudinal measurements of circulating miRNAs into the Athlete Biological Passport is proposed as an efficient strategy for the implementation of these new biomarkers. Furthermore, potential challenges related to the transition of measurements of circulating miRNAs from research settings to practical anti-doping applications are presented.

Hepcidin as a new biomarker for detecting autologous blood transfusion

Autologous blood transfusion (ABT) is an efficient way to increase sport performance. It is also the most challenging doping method to detect. At present, individual follow-up of haematological variables via the athlete biological passport (ABP) is used to detect it. Quantification of a novel hepatic peptide called hepcidin may be a new alternative to detect ABT. In this prospective clinical trial, healthy subjects received a saline injection for the control phase, after which they donated blood that was stored and then transfused 36 days later. The impact of ABT on hepcidin as well as haematological parameters, iron metabolism, and inflammation markers was investigated. Blood transfusion had a particularly marked effect on hepcidin concentrations compared to the other biomarkers, which included haematological variables. Hepcidin concentrations increased significantly: 12 hr and 1 day after blood reinfusion, these concentrations rose by seven- and fourfold, respectively. No significant change was observed in the control phase. Hepcidin quantification is a cost-effective strategy that could be used in an "ironomics" strategy to improve the detection of ABT.

Erythropoietin protects the tubular basement membrane by promoting the bone marrow to release extracellular vesicles containing tPA-targeting miR-144

Renal fibrosis is an inevitable outcome of chronic kidney disease (CKD). Erythropoietin (EPO) has been recently reported to be able to mitigate renal fibrosis. The mechanism underlying the protective effect of EPO, however, remains elusive. In the present study, employing a mouse model of renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction (UUO), we demonstrated that EPO markedly reduced the disruption of the tubular basement membrane (TBM) through attenuating the activation of tissue plasminogen activator (tPA) and matrix metalloproteinase 9 (MMP9), the major matrix proteolytic network in the obstructed kidney. Instead of acting directly on tPA in the kidney, EPO strongly increased the level of circulating microRNA (miR)-144, which was delivered to the injured renal fibroblasts via extracellular vesicles (EVs) to target the tPA 3′-untranslated region and suppress tPA expression. The protective effect of EPO on mouse TBM was inhibited by miR-144 antagomir. Furthermore, in vitro results confirmed that EPO could stimulate bone marrow-derived Sca-1+CD44+CD11b−CD19− cells to secrete miR-144-containing EVs, which markedly suppressed tPA expression, as well as metalloproteinase 9 (MMP9) level and activity, in cultured renal fibroblasts. In conclusion, our study provides the first evidence that EPO protects mouse renal TBM through promoting bone marrow cells to generate and secrete miR-144, which, in turn, is efficiently delivered into the mouse kidney via EVs to inhibit the activation of the tPA/MMP9-mediated proteolytic network. This finding thus suggests that EPO, a hormone widely used to treat anemia in CKD, is a potential therapeutic strategy for renal fibrosis.

Rapid isolation and detection of erythropoietin in blood plasma by magnetic core gold nanoparticles and portable Raman spectroscopy

Isolating, purifying, and identifying proteins in complex biological matrices are often difficult, time consuming, and unreliable. Herein we describe a rapid screening technique for proteins in biological matrices that combines selective protein isolation with direct surface enhanced Raman spectroscopy (SERS) detection. Magnetic core gold nanoparticles were synthesized, characterized, and subsequently functionalized with recombinant human erythropoietin (rHuEPO)-specific antibody. The functionalized nanoparticles were used to capture rHuEPO from horse blood plasma within 15 min. The selective binding between the protein and the functionalized nanoparticles was monitored by SERS. The purified protein was then released from the nanoparticles' surface and directly spectroscopically identified on a commercial nanopillar SERS substrate. ELISA independently confirmed the SERS identification and quantified the released rHuEPO. Finally, the direct SERS detection of the extracted protein was successfully demonstrated for in-field screening by a handheld Raman spectrometer within 1 min sample measurement time.

FROM THE CLINICAL EDITOR

The rapid detection of recombinant human erythropoietin (rHuEPO) is important in competitive sports to screen for doping offences. In this article, the authors reported their technique of direct surface enhanced Raman spectroscopy (SERS) detection using magnetic core gold nanoparticles functionalized with recombinant human erythropoietin-specific antibody. The findings should open a new way for future detection of other proteins.