Imperial College London

DrAliAbbara

Faculty of MedicineDepartment of Metabolism, Digestion and Reproduction

NIHR Clinician Scientist
 
 
 
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+44 (0)20 3313 4843ali.abbara Website

 
 
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6N6Commonwealth BuildingHammersmith Campus

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Summary

 

Publications

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77 results found

Yang L, Demetriou L, Wall MB, Mills EG, Wing VC, Thurston L, Schaufelberger CN, Owen BM, Abbara A, Rabiner EA, Comninos AN, Dhillo WSet al., 2021, The Effects of Kisspeptin on Brain Response to Food Images and Psychometric Parameters of Appetite in Healthy Men., J Clin Endocrinol Metab, Vol: 106, Pages: e1837-e1848

CONTEXT: The hormone kisspeptin has crucial and well-characterized roles in reproduction. Emerging data from animal models also suggest that kisspeptin has important metabolic effects including modulation of food intake. However, to date there have been no studies exploring the effects of kisspeptin on brain responses to food stimuli in humans. OBJECTIVE: This work aims to investigate the effects of kisspeptin administration on brain responses to visual food stimuli and psychometric parameters of appetite, in healthy men. DESIGN: A double-blinded, randomized, placebo-controlled, crossover study was conducted. PARTICIPANTS: Participants included 27 healthy, right-handed, eugonadal men (mean ± SEM: age 26.5 ± 1.1 years; body mass index 23.9 ± 0.4 kg/m2). INTERVENTION: Participants received an intravenous infusion of 1 nmol/kg/h of kisspeptin or rate-matched vehicle over 75 minutes. MAIN OUTCOME MEASURES: Measurements included change in brain activity on functional magnetic resonance imaging in response to visual food stimuli and change in psychometric parameters of appetite, during kisspeptin administration compared to vehicle. RESULTS: Kisspeptin administration at a bioactive dose did not affect brain responses to visual food stimuli or psychometric parameters of appetite compared to vehicle. CONCLUSIONS: This is the first study in humans investigating the effects of kisspeptin on brain regions regulating appetite and demonstrates that peripheral administration of kisspeptin does not alter brain responses to visual food stimuli or psychometric parameters of appetite in healthy men. These data provide key translational insights to further our understanding of the interaction between reproduction and metabolism.

Journal article

Khoo B, Tan T, Clarke S, Mills E, Patel B, Modi M, Phylactou M, Eng PC, Thurston L, Alexander E, Meeran K, Comninos A, Abbara A, Dhillo Wet al., 2021, Thyroid function before, during and after COVID-19, Journal of Clinical Endocrinology and Metabolism, Vol: 106, Pages: e803-e811, ISSN: 0021-972X

Context: The effects of COVID-19 on the thyroid axis remain uncertain. Recent evidence has been conflicting, with both thyrotoxicosis and suppression of thyroid function reported. Objective: We aimed to detail the acute effects of COVID-19 on thyroid function and determine if these effects persisted upon recovery from COVID-19. Design: Cohort observational study. Participants and setting: Adult patients admitted to Imperial College Healthcare National Health Service Trust, London, UK with suspected COVID-19 between March 9 to April 22, 2020 were included, excluding those with pre-existing thyroid disease and those missing either free thyroxine (FT4) or TSH measurements. Of 456 patients, 334 had COVID-19 and 122 did not.Main Outcome Measures: TSH and FT4 measurements at admission, and where available, those taken in 2019 and at COVID-19 follow-up. Results: Most patients (86·6%) presenting with COVID-19 were euthyroid, with none presenting with overt thyrotoxicosis. Patients with COVID-19 had a lower admission TSH and FT4 compared to those without COVID-19. In the COVID-19 patients with matching baseline thyroid function tests from 2019 (n=185 for TSH and 104 for FT4), both TSH and FT4 were reduced at admission compared to baseline. In a complete cases analysis of COVID-19 patients with TSH measurements at follow-up, admission and baseline (n=55), TSH was seen to recover to baseline at follow-up. Conclusions: Most patients with COVID-19 present with euthyroidism. We observed mild reductions in TSH and FT4 in keeping with a non-thyroidal illness syndrome. Furthermore, in survivors of COVID-19, thyroid function tests at follow-up returned to baseline.

Journal article

Abbara A, Phylactou M, Dhillo WS, 2021, Commentary on "Pharmacodynamic Activity of the Novel Neurokinin-3 Receptor Antagonist SJX-653 in Healthy Men"., J Clin Endocrinol Metab, Vol: 106, Pages: e1028-e1030

Journal article

Phylactou M, Clarke S, Patel B, Baggaley C, Jayasena C, Kelsey T, Comninos A, Dhillo W, Abbara Aet al., 2020, Clinical and biochemical discriminants between functional hypothalamic amenorrhoea (FHA) and polycystic ovary syndrome (PCOS), Clinical Endocrinology, ISSN: 0300-0664

BackgroundSecondary oligo/amenorrhoea occurs in 3%–5% of women of reproductive age. The two most common causes are polycystic ovary syndrome (PCOS) (2%–13%) and functional hypothalamic amenorrhoea (FHA) (1%–2%). Whilst both conditions have distinct pathophysiology and their diagnosis is supported by guidelines, in practice, differentiating these two common causes of menstrual disturbance is challenging. Moreover, both diagnoses are qualified by the need to first exclude other causes of menstrual disturbance.AimTo review clinical, biochemical and radiological parameters that could aid the clinician in distinguishing PCOS and FHA as a cause of menstrual disturbance.ResultsFHA is uncommon in women with BMI > 24 kg/m2, whereas both PCOS and FHA can occur in women with lower BMIs. AMH levels are markedly elevated in PCOS; however, milder increases may also be observed in FHA. Likewise, polycystic ovarian morphology (PCOM) is more frequently observed in FHA than in healthy women. Features that are differentially altered between PCOS and FHA include LH, androgen, insulin, AMH and SHBG levels, endometrial thickness and cortisol response to CRH. Other promising diagnostic tests with the potential to distinguish these two conditions pending further study include assessment of 5‐alpha‐reductase activity, leptin, INSL3, kisspeptin and inhibin B levels.ConclusionFurther data directly comparing the discriminatory potential of these markers to differentiate PCOS and FHA in women with secondary amenorrhoea would be of value in defining an objective probability for PCOS or FHA diagnosis.

Journal article

Mills EG, Izzi-Engbeaya C, Abbara A, Comninos AN, Dhillo WSet al., 2020, Functions of galanin, spexin and kisspeptin in metabolism, mood and behaviour, Nature Reviews Endocrinology, Vol: 17, Pages: 97-113, ISSN: 1759-5029

The bioactive peptides galanin, spexin and kisspeptin have a common ancestral origin and their pathophysiological roles are increasingly the subject of investigation. Evidence suggests that these bioactive peptides play a role in the regulation of metabolism, pancreatic β-cell function, energy homeostasis, mood and behaviour in several species, including zebrafish, rodents and humans. Galanin signalling suppresses insulin secretion in animal models (but not in humans), is potently obesogenic and plays putative roles governing certain evolutionary behaviours and mood modulation. Spexin decreases insulin secretion and has potent anorectic, analgesic, anxiolytic and antidepressive-like effects in animal models. Kisspeptin modulates glucose-stimulated insulin secretion, food intake and/or energy expenditure in animal models and humans. Furthermore, kisspeptin is implicated in the control of reproductive behaviour in animals, modulation of human sexual and emotional brain processing, and has antidepressive and fear-suppressing effects. In addition, galanin-like peptide is a further member of the galaninergic family that plays emerging key roles in metabolism and behaviour. Therapeutic interventions targeting galanin, spexin and/or kisspeptin signalling pathways could therefore contribute to the treatment of conditions ranging from obesity to mood disorders. However, many gaps and controversies exist, which must be addressed before the therapeutic potential of these bioactive peptides can be established.

Journal article

Abbara A, Eng PC, Phylactou M, Clarke SA, Mills E, Chia G, Yang L, Izzi-Engbeaya C, Smith N, Jayasena CN, Comninos AN, Anand-Ivell R, Rademaker J, Xu C, Quinton R, Pitteloud N, Dhillo WSet al., 2020, Kisspeptin-54 accurately identifies hypothalamic GnRH neuronal dysfunction in men with congenital hypogonadotropic hypogonadism., Neuroendocrinology

BACKGROUND: Hypogonadotropic hypogonadism is hypogonadism due to either hypothalamic or pituitary dysfunction. Whilst gonadotropin releasing hormone (GnRH) can directly test pituitary function, no specific test of hypothalamic function exists. Kisspeptin-54 (KP54) is a neuropeptide that directly stimulates hypothalamic GnRH-release and thus could be used to specifically interrogate hypothalamic function. Congenital Hypogonadotropic Hypogonadism (CHH) is typically due to variants in genes that control hypothalamic GnRH neuronal migration of function. Thus, we investigated whether KP54 could accurately identify hypothalamic dysfunction in men with CHH. METHODS: Men with CHH (n=21) and healthy eugonadal men (n=21) received an intravenous bolus of either GnRH (100mcg), or KP54 (6.4nmol/kg), on two occasions, and were monitored for 6hrs after administration of each neuropeptide. RESULTS: Maximal LH-rise after KP54 was significantly greater in healthy men (12.5 iU/L) than in men with CHH (0.4 iU/L; P<0.0001). KP54 more accurately differentiated CHH men from healthy men than GnRH (auROC curve KP54: 1.0, 95%CI 1.0-1.0; GnRH: 0.88, 95%CI 0.76-0.99). Indeed, all CHH men had an LH-rise <2.0 iU/L following KP54, whereas all healthy men had an LH-rise >4.0 iU/L. Anosmic men with CHH (i.e. Kallmann syndrome) had even lower LH-rises after KP54 than did normosmic men with CHH (P=0.017). Likewise, men identified to have pathogenic/likely pathogenic variants in CHH genes had even lower LH-rises after KP54 than other men with CHH (P=0.035). CONCLUSION: KP54 fully discriminated men with CHH from healthy men. Thus, KP54 could be used to specifically interrogate hypothalamic GnRH neuronal function in patients with congenital hypogonadotropic hypogonadism.

Journal article

Abbara A, Eng P, Phylactou M, Clarke S, Richardson R, sykes C, Phumsatitpong C, Mills E, Modi M, Izzi-Engbeaya C, Papadopoulou D, Purugganan K, Jayasena C, Webber L, salim R, Owen B, Bech P, Comninos A, McArdle C, violitis M, Tsaneva-Atanasova K, Moenter S, Hanyaloglu A, Dhillo Wet al., 2020, Kisspeptin receptor agonist has therapeutic potential for female reproductive disorders., Journal of Clinical Investigation, Vol: 130, Pages: 6739-6753, ISSN: 0021-9738

BACKGROUND. Kisspeptin is a key regulator of hypothalamic gonadotropin-releasing hormone (GnRH) neurons and is essential for reproductive health. A specific kisspeptin receptor (KISS1R) agonist could significantly expand the potential clinical utility of therapeutics targeting the kisspeptin pathway. Herein, we investigate the effects of a KISS1R agonist, MVT-602, in healthy women and in women with reproductive disorders.METHODS. We conducted in vivo and in vitro studies to characterize the action of MVT-602 in comparison with native kisspeptin-54 (KP54). We determined the pharmacokinetic and pharmacodynamic properties of MVT-602 (doses 0.01 and 0.03 nmol/kg) versus KP54 (9.6 nmol/kg) in the follicular phase of healthy women (n = 9), and in women with polycystic ovary syndrome (PCOS; n = 6) or hypothalamic amenorrhea (HA; n = 6). Further, we investigated their effects on KISS1R-mediated inositol monophosphate (IP1) and Ca2+ signaling in cell lines and on action potential firing of GnRH neurons in brain slices.RESULTS. In healthy women, the amplitude of luteinizing hormone (LH) rise was similar to that after KP54, but peaked later (21.4 vs. 4.7 hours; P = 0.0002), with correspondingly increased AUC of LH exposure (169.0 vs. 38.5 IU∙h/L; P = 0.0058). LH increases following MVT-602 were similar in PCOS and healthy women, but advanced in HA (P = 0.004). In keeping with the clinical data, MVT-602 induced more potent signaling of KISS1R-mediated IP1 accumulation and a longer duration of GnRH neuron firing than KP54 (115 vs. 55 minutes; P = 0.0012).CONCLUSION. Taken together, these clinical and mechanistic data identify MVT-602 as having considerable therapeutic potential for the treatment of female reproductive disorders.TRIAL REGISTRATION. International Standard Randomised Controlled Trial Number (ISRCTN) Registry, ISRCTN21681316.FUNDING. National Institute for Health Research and NIH.

Journal article

Karah N, Rafei R, Elamin W, Ghazy A, Abbara A, Hamze M, Uhlin BEet al., 2020, Guideline for Urine Culture and Biochemical Identification of Bacterial Urinary Pathogens in Low-Resource Settings., Diagnostics, Vol: 10, ISSN: 2075-4418

Medical diagnosis in low-resource settings is confronted by the lack of suitable guidelines, protocols and checklists. Online-accessible procedural documents are difficult to find, might be mistranslated or interpreted and usually do not address the needs of developing countries. Urinalysis, one of the most frequently performed diagnostic examinations worldwide, involves a series of tests aiming to detect particular disorders, such as urinary tract infections, kidney disease and diabetes. In this guideline, we present an alternative approach for clinical laboratories with limited resources to identify common bacterial uropathogens. We propose dividing the identification plan into two levels. The implicated pathogen will first be assigned into a bacterial group, basic identification, against which a suitable panel of antimicrobial agents shall be selected for the antimicrobial susceptibility testing (AST). Characterization of the pathogen to the genus or species level, advanced identification, will then be performed to ensure correct reading of the AST results and determine the epidemiology of clinically significant pathogens. Most of the proposed steps in our guideline are tailored to meet the needs of clinical laboratories in low-resource settings. Such guidelines are needed to strengthen the capacity of regional pathology laboratories and to enhance international initiatives on antimicrobial resistance and health equity.

Journal article

Izzi-Engbeaya C, Abbara A, Cass A, Dhillo Wet al., 2020, Using Aptamers as a Novel Method for Determining GnRH/LH Pulsatility, International Journal of Molecular Sciences, Vol: 21, ISSN: 1422-0067

Aptamers are a novel technology enabling the continuous measurement of analytes in blood and other body compartments, without the need for repeated sampling and the associated reagent costs of traditional antibody-based methodologies. Aptamers are short single-stranded synthetic RNA or DNA that recognise and bind to specific targets. The conformational changes that can occur upon aptamer–ligand binding are transformed into chemical, fluorescent, colour changes and other readouts. Aptamers have been developed to detect and measure a variety of targets in vitro and in vivo. Gonadotropin-releasing hormone (GnRH) is a pulsatile hypothalamic hormone that is essential for normal fertility but difficult to measure in the peripheral circulation. However, pulsatile GnRH release results in pulsatile luteinizing hormone (LH) release from the pituitary gland. As such, LH pulsatility is the clinical gold standard method to determine GnRH pulsatility in humans. Aptamers have recently been shown to successfully bind to and measure GnRH and LH, and this review will focus on this specific area. However, due to the adaptability of aptamers, and their suitability for incorporation into portable devices, aptamer-based technology is likely to be used more widely in the future.

Journal article

Abbara A, Hunjan T, NGOC ANH Ho V, Clarke S, Comninos A, Izzi-Engbeaya C, ho T, Trew G, hramyka A, kelsey T, salim R, humaidan P, vuong L, Dhillo Wet al., 2020, Endocrine requirements for oocyte maturation following hCG, GnRH agonist and kisspeptin during IVF treatment, Frontiers in Endocrinology, Vol: 11, ISSN: 1664-2392

Objective: The maturation of oocytes to acquire competence for fertilization is critical to the success of in vitro fertilization (IVF) treatment. It requires LH-like exposure, provided by either human chorionic gonadotropin (hCG), or gonadotropin releasing hormone agonist (GnRHa). More recently, the hypothalamic stimulator, kisspeptin, was used to mature oocytes. Herein, we examine the relationship between the endocrine changes following these agents and oocyte maturation.Design: Retrospective cohort study.Methods: Prospectively collected hormonal data from 499 research IVF cycles triggered with either hCG, GnRHa, or kisspeptin were evaluated.Results: HCG-levels (121 iU/L) peaked at 24 h following hCG, whereas LH-levels peaked at ~4 h following GnRHa (140 iU/L), or kisspeptin (41 iU/L). HCG-levels were negatively associated with body-weight, whereas LH rises following GnRHa and kisspeptin were positively predicted by pre-trigger LH values. The odds of achieving the median mature oocyte yield for each trigger were increased by hCG/LH level. Progesterone rise during oocyte maturation occurred precipitously following each trigger and strongly predicted the number of mature oocytes retrieved. Progesterone rise was positively associated with the hCG-level following hCG trigger, but negatively with LH rise following all three triggers. The rise in progesterone per mature oocyte at 12 h was greater following GnRHa than following hCG or kisspeptin triggers.Conclusion: The endocrine response during oocyte maturation significantly differed by each trigger. Counter-intuitively, progesterone rise during oocyte maturation was negatively associated with LH rise, even when accounting for the number of mature oocytes retrieved. These data expand our understanding of the endocrine changes during oocyte maturation and inform the design of future precision-triggering protocols.

Journal article

Tan T, Khoo B, Mills EG, Phylactou M, Patel B, Eng PC, Thurston L, Muzi B, Meeran K, Prevost AT, Comninos AN, Abbara A, Dhillo WSet al., 2020, Cortisol concentrations and mortality from COVID-19 - Authors' reply, The Lancet Diabetes and Endocrinology, Vol: 8, Pages: 809-810, ISSN: 2213-8595

Journal article

Jayasena CN, Sharma A, Abbara A, Rong L, White CJ, Hoskin SG, Khanjani S, Crawford MJ, Ramsay JW, Minhas S, Dhillo WSet al., 2020, Burdens and awareness of adverse self-reported lifestyle factors in men with sub-fertility: a cross-sectional study in 1149 men., Clinical Endocrinology, Vol: 93, Pages: 312-321, ISSN: 0300-0664

BACKGROUND: There are no current pharmacological therapies to improve sperm quality in men with sub-fertility. Reducing the exposure to lifestyle risk factor (LSF) is currently the only intervention for improving sperm quality in men with sub-fertility. No previous study has investigated what proportion of men with sub-fertility are exposed to adverse lifestyle factors. Furthermore, it is not known to what extent men with sub-fertility are aware of lifestyle factors potentially adversely impacting their fertility. METHODS: A cross-sectional anonymous questionnaire-based study on self-reported exposure and awareness of LSF was conducted in 1149 male partners of couples investigated for sub-fertility in a tertiary andrology centre in London, UK. RESULTS: Seventy-percent of men investigated for sub-fertility had ≥1 LSF, and twenty-nine-percent had ≥2 LSF. Excessive alcohol consumption was the most common LSF (40% respondents). Seventeen-percent of respondents used recreational drugs (RD) regularly, but only 32% of RD users believed RD impair male fertility. Twenty-five-percent of respondents were smokers, which is higher than the UK average (20%). Twenty-seven percent of respondents had a waist circumference (WC) >36inches (91cm), and 4% had WC >40inches (102cm). Seventy-nine-percent of respondents wanted further lifestyle education to improve their fertility. CONCLUSIONS: Our data suggest that men with sub-fertility are: (1) exposed to one or more LSF; (2) have incomplete education about how LSF may cause male sub-fertility; (3) want more education about reducing LSF. Further studies are needed to investigate the potential of enhanced education of men about LSF to treat couples with sub-fertility.

Journal article

Abbara A, Dhillo WS, 2020, Makorin rings the kisspeptin bell to signal pubertal initiation., Journal of Clinical Investigation, Vol: 130, Pages: 3957-3960, ISSN: 0021-9738

The signals maintaining quiescence of the reproductive endocrine axis during childhood before its reawakening at puberty had been enigmatic. Studies in patients with abnormal puberty have illuminated the identity of the signals; kisspeptin has emerged as a major stimulator of puberty, and makorin RING finger protein 3 (MKRN3) as an inhibitory signal that prevents premature initiation of puberty. In this issue of the JCI, Abreu et al. investigated the mechanism by which MKRN3 regulates pubertal onset. The authors found that a reduction in MKRN3 alleviated the constraint on kisspeptin-expressing neurons to allow pubertal initiation, a phenomenon observed across species, including nonhuman primates. Further, the ubiquitinase activity of MKRN3 required its RING finger domain, in order to repress the promoter activity of genes encoding kisspeptin and neurokinin B. These data advance our understanding of the regulation of kisspeptin-expressing neurons by MKRN3 to initiate puberty.

Journal article

Tan T, Khoo B, Mills EG, Phylactou M, Patel B, Eng PC, Thurston L, Muzi B, Meeran K, Prevost AT, Comninos AN, Abbara A, Dhillo WSet al., 2020, Association between high serum total cortisol concentrations and mortality from COVID-19, The Lancet Diabetes and Endocrinology, Vol: 8, Pages: 659-660, ISSN: 2213-8595

Journal article

Izzi-Engbeaya C, Mills E, Yang L, Minnion J, Tharakan G, Abbara A, Comninos A, Tan T, Dhillo Wet al., 2020, Acute effects of glucagon on reproductive hormone secretion in healthy men, Journal of Clinical Endocrinology and Metabolism, Vol: 105, ISSN: 0021-972X

ContextGlucagon increases energy expenditure; consequently, glucagon receptor agonists are in development for the treatment of obesity. Obesity negatively affects the reproductive axis, and hypogonadism itself can exacerbate weight gain. Therefore, knowledge of the effects of glucagon receptor agonism on reproductive hormones is important for developing therapeutics for obesity; but reports in the literature about the effects of glucagon receptor agonism on the reproductive axis are conflicting.ObjectiveThe objective of this work is to investigate the effect of glucagon administration on reproductive hormone secretion in healthy young men.DesignA single-blinded, randomized, placebo-controlled crossover study was conducted.SettingThe setting of this study was the Clinical Research Facility, Imperial College Healthcare NHS Trust.ParticipantsEighteen healthy eugonadal men (mean ± SEM: age 25.1 ± 1.0 years; body mass index 22.5 ± 0.4 kg/m2; testosterone 21.2 ± 1.2 nmol/L) participated in this study.InterventionAn 8-hour intravenous infusion of 2 pmol/kg/min glucagon or rate-matched vehicle infusion was administered.Main Outcome MeasuresLuteinizing hormone (LH) pulsatility; LH, follicle-stimulating hormone (FSH), and testosterone levels were measured.ResultsAlthough glucagon administration induced metabolic effects (insulin area under the curve: vehicle 1065 ± 292 min.µU/mL vs glucagon 2098 ± 358 min.µU/mL, P < .001), it did not affect LH pulsatility (number of LH pulses/500 min: vehicle 4.7 ± 0.4, glucagon 4.2 ± 0.4, P = .22). Additionally, there were no significant differences in circulating LH, FSH, or testosterone levels during glucagon administration compared with vehicle administration.ConclusionsAcute administration of a metabolically active dose of glucagon does not alter reproductive hormone secretion in healthy men. These data are important for the continued development of glucagon-based tre

Journal article

Abbara A, Clarke S, Brewster R, Simmonard A, Eng PC, Phylactou M, Papadopoulou D, Izzi-Engbeaya C, Sam A, Wernig F, Jonauskyte E, Comninos A, Meeran K, Kelsey T, Dhillo Wet al., 2020, Pharmacodynamic response to anti-thyroid drugs in Graves’ hyperthyroidism, Frontiers in Endocrinology, Vol: 11, ISSN: 1664-2392

Objective: Graves' disease is the commonest cause of hyperthyroidism in populations with sufficient dietary iodine intake. Anti-thyroid drugs (ATD) are often used as the initial treatment for Graves' hyperthyroidism, however there is a paucity of data relating the dose of ATD therapy to the effect on thyroid hormone levels, increasing the risk of both over- and under-treatment. We aimed to determine the pharmacodynamic response to the ATD carbimazole.Design: Retrospective cohort study.Methods: Participants were patients (n = 441) diagnosed with Graves' disease at Imperial College Healthcare NHS Trust between 2009 and 2018. The main outcome measure was change in thyroid hormone levels in response to ATD.Results: Baseline thyroid hormone levels were positively associated with TSH receptor antibody titres (P < 0.0001). Baseline free triiodothyronine (fT3) were linearly related to free thyroxine (fT4) levels in the hyperthyroid state (fT3 = fT4*0.97–11), and fell proportionately with carbimazole. The percentage falls in fT4 and fT3 per day were associated with carbimazole dose (P < 0.0001). The magnitude of fall in thyroid hormones after the same dose of carbimazole was lower during follow up than at the initiation visit. The fall in thyroid hormone levels approximated to a linear response if assessed at least 3 weeks after commencement of carbimazole. Following withdrawal of antithyroid drug treatment, the risk of relapse was greater in patients with higher initial fT4, initial TSH receptor antibody titre, males, smokers, and British Caucasian ethnicity.Conclusion: We identify a dose-response relationship for fall in thyroid hormones in response to carbimazole to aid in the selection of dose for Graves' hyperthyroidism.

Journal article

Yang L, Demetriou L, Wall M, Mills E, Zargaran D, Sykes M, Prague J, Abbara A, Owen B, Bassett P, Rabiner E, Comninos A, Dhillo Wet al., 2020, Kisspeptin enhances brain responses to olfactory and visual cues of attraction in men, JCI insight, Vol: 5, ISSN: 2379-3708

Successful reproduction is a fundamental physiological process which relies on the integration of sensory cues of attraction with appropriate emotions and behaviors and the reproductive axis. However, the factors responsible for this integration remain largely unexplored. Using functional neuroimaging, hormonal and psychometric analyses, we demonstrate that the reproductive hormone kisspeptin enhances brain activity in response to olfactory and visual cues of attraction in men. Furthermore, the brain regions enhanced by kisspeptin correspond to areas within the olfactory and limbic systems that govern sexual behavior and perception of beauty as well as overlapping with its endogenous expression pattern. Of key functional and behavioral significance, we observed that kisspeptin was most effective in men with lower sexual quality of life scores. As such, our results reveal a previously undescribed attraction pathway in humans activated by kisspeptin, and identify kisspeptin signaling as a new therapeutic target for related reproductive and psychosexual disorders.

Journal article

Izzi-Engbeaya C, Dhillo W, Tan T, Abbara A, Comninos A, Bech P, Minnion Jet al., 2020, Effects of glucagon-like peptide-1 on the reproductive axis in healthy men, Journal of Clinical Endocrinology and Metabolism, Vol: 105, Pages: 1-7, ISSN: 0021-972X

ContextGlucagon-like peptide-1 (GLP-1) potently reduces food intake and augments glucose-stimulated insulin secretion. Recent animal data suggest that GLP-1 may also influence reproduction. As GLP-1 receptor agonists are currently widely used in clinical practice to treat obesity/type 2 diabetes, it is necessary to determine the effects of GLP-1 on the reproductive system in humans.ObjectiveTo investigate the effects of GLP-1 administration on the reproductive axis in humans.DesignSingle-blind, randomized, placebo-controlled crossover study.SettingClinical Research Facility, Imperial College Healthcare NHS Trust.ParticipantsEighteen healthy men (mean age 24.7 ± 0.1years, mean BMI 22.1 ± 0.4kg/m2).InterventionEight-hour intravenous infusion of 0.8 pmol/kg/min GLP-1 or rate-matched vehicle infusion.Main Outcome MeasuresNumber of luteinizing hormone (LH) pulses, LH, follicle-stimulating hormone (FSH), and testosterone levels.ResultsThe number of LH pulses (number of LH pulses/500 min: vehicle 4.2 ± 0.4, GLP-1 4.5 ± 0.3, P = 0.46), LH area under the curve (AUC) (vehicle 1518 ± 88min.IU/L, GLP-1 1524 ± 101min.IU/L, P = 0.95), follicle-stimulating hormone AUC (vehicle 1210 ± 112 min IU/L, GLP-1 1216 ± 112 min IU/L, P = 0.86), and testosterone AUC (vehicle 10893 ± 615 min nmol/L, GLP-1 11088 ± 792 min nmol/L, P = 0.77) did not significantly differ during vehicle and GLP-1 administration. Glucagon-like peptide-1 significantly reduced food intake (vehicle 15.7 ± 1.3 kcal/kg, GLP-1 13.4 ± 1.3 kcal/kg, P = 0.01).ConclusionsIn contrast to the animal literature, our data demonstrate that acute GLP-1 administration does not affect reproductive hormone secretion in healthy men.

Journal article

Dragan M, Nguyen M-U, Guzman S, Goertzen C, Brackstone M, Dhillo WS, Bech PR, Clarke S, Abbara A, Tuck AB, Hess DA, Pine SR, Zong W-X, Wondisford FE, Su X, Babwah AV, Bhattacharya Met al., 2020, G protein-coupled kisspeptin receptor induces metabolic reprograming and tumorigenesis in estrogen receptor-negative breast cancer, Cell Death and Disease, Vol: 11, ISSN: 2041-4889

Triple-negative breast cancer (TNBC) is a highly metastatic and deadly disease. TNBC tumors lack estrogen receptor (ERα), progesterone receptor (PR), and HER2 (ErbB2) and exhibit increased glutamine metabolism, a requirement for tumor growth. The G protein-coupled kisspeptin receptor (KISS1R) is highly expressed in patient TNBC tumors and promotes malignant transformation of breast epithelial cells. This study found that TNBC patients displayed elevated plasma kisspeptin levels compared with healthy subjects. It also provides the first evidence that in addition to promoting tumor growth and metastasis in vivo, KISS1R-induced glutamine dependence of tumors. In addition, tracer-based metabolomics analyses revealed that KISS1R promoted glutaminolysis and nucleotide biosynthesis by increasing c-Myc and glutaminase levels, key regulators of glutamine metabolism. Overall, this study establishes KISS1R as a novel regulator of TNBC metabolism and metastasis, suggesting that targeting KISS1R could have therapeutic potential in the treatment of TNBC.

Journal article

Prague J, Abbara A, Comninos A, Jayasena C, higham C, adaway J, keevil B, veldhuis J, Dhillo Wet al., 2020, Neurokinin 3 receptor antagonists do not increase FSH or estradiol secretion in menopausal women, Journal of the Endocrine Society, Vol: 4, ISSN: 2472-1972

Background: Neurokinin 3 receptor (NK3R) antagonism is a promising novel treatment for menopausal flashes. However, to avoid adverse hormonal effects it is clinically important to first confirm whether gonadotropin and estradiol concentrations change as a result of their administration. Methods: Single-center, randomized, double-blind, placebo-controlled, crossover trial of an oral NK3R antagonist (MLE4901) in 28 women aged 40-62yrs, experiencing >7 hot flashes/24h; some bothersome or severe (Clinicaltrials.gov NCT02668185). Weekly serum gonadotropins and estradiol levels were measured using commercially available automated immunoassays a priori. Serum estradiol was also measured post hoc using a highly sensitive direct assay by liquid chromatography tandem mass spectrometry. Hormone levels were compared by the paired sample t-tests or by the Wilcoxon matched-pairs signed rank test, as appropriate for the distribution of the data. Results: Mean (SD) serum FSH concentration was not significantly increased when taking MLE4901 (72.07 ±19.81iU/L) compared to placebo (70.03 ±19.56iU/L), p=0.26. Serumestradiol was also not significantly altered, irrespective of which assay method was used (median IQR of serum estradiol by immunoassay: placebo 36 ±3pmol/L, MLE4901 36 ± 1pmol/L, p=0.21; median serum highly sensitive estradiol: placebo 12 ± 16pmol/L, MLE4901 5 13 ± 15pmol/L, p=0.70). However, mean (SD) serum LH concentration significantly decreased with MLE4901 (27.63 ± 9.76iU/L) compared to placebo (30.26 ± 9.75iU/L), p=0.0024. Implication: NK3R antagonists do not increase serum estradiol or FSH despite their reduction in hot flashes. This is clinically significant; and highly reassuring for women who have a contraindication to conventional hormone therapy such as prior/existing breast cancer and/or thromboembolism.

Journal article

Izzi-Engbeaya C, Jones S, Crustna Y, Machenahalli PC, Papadopoulou D, Modi M, Panayi C, Starikova J, Eng PC, Phylactou M, Mills E, Yang L, Ratnasabapathy R, Sykes M, Plumptre I, Coumbe B, Wing V, Pacuszka E, Bech P, Minnion J, Tharakan G, Tan T, Veldhuis J, Abbara A, Comninos AN, Dhillo WSet al., 2019, Effects of peptide-YY on the hypothalamic-pituitary-gonadal axis in healthy men, Journal of Clinical Endocrinology and Metabolism, Vol: 105, Pages: 1-6, ISSN: 0021-972X

ContextCentral and peripheral administration of peptide-YY (PYY) has potent anorectic effects, and PYY analogues are under development as anti-obesity treatments. Recent animal data suggest PYY may also influence the reproductive axis, however the effects of PYY on the human reproductive system are unknown.ObjectiveTo investigate the effects of PYY administration on the reproductive axis in healthy young men.DesignSingle-blind, randomised, placebo-controlled crossover study.SettingClinical Research Facility, Imperial College Healthcare NHS Trust.ParticipantsEighteen healthy eugonadal men (mean age 24.1±0.9years, mean BMI 22.2±0.4kg/m2).InterventionEight-hour intravenous infusion of 0.4pmol/kg/min PYY3-36 or rate-matched vehicle infusion.ResultsThe number of LH pulses (mean number of LH pulses/8hours: PYY 4.4±0.3 vs vehicle 4.4±0.4, p>0.99), LH area under the curve (AUC) (PYY 1503±79IU.min/L vs vehicle 1574±86IU.min/L, p=0.36), FSH AUC (PYY 1158±513IU.min/L vs vehicle 1199±476IU.min/L, p=0.49) and testosterone AUC (PYY 10485±684IU.min/L vs vehicle 11133±803IU.min/L, p=0.24) were similar during PYY and vehicle infusions.ConclusionsAcute intravenous infusion of 0.4pmol/kg/min PYY does not affect the reproductive axis in healthy men.

Journal article

Abbara A, Eng PC, Phylactou M, Clarke SA, Tia H, Roberts R, Vimalesvaran S, Christopoulos G, Islam R, Purugganan K, Comninos AN, Trew GH, Salim R, Hramyka A, Owens L, Kelsey T, Dhillo WSet al., 2019, Anti-Mullerian Hormone (AMH) in the diagnosis of menstrual disturbance due to polycystic ovarian syndrome, Frontiers in Endocrinology, Vol: 10, Pages: 1-11, ISSN: 1664-2392

Introduction: Polycystic ovarian syndrome (PCOS) is a leading cause of female subfertility worldwide, however due to the heterogeneity of the disorder, the criteria for diagnosis remains subject to conjecture. In the present study, we evaluate the utility of serum Anti-Müllerian Hormone (AMH) in the diagnosis of menstrual disturbance due to PCOS.Method: Menstrual cycle length, serum AMH, gonadotropin and sex-hormone levels, total antral follicle count (AFC), body mass index (BMI) and ovarian morphology on ultrasound were analyzed in a cohort of 187 non-obese women, aged 18–35 years, screened for participation in a clinical trial of fertility treatment between 2013 and 2016 at a tertiary reproductive endocrine center.Results: Serum AMH was higher in women with menstrual disturbance when compared to those with regular cycles (65.6 vs. 34.8 pmol/L; P < 0.0001). The odds of menstrual disturbance was increased 28.5-fold (95% CI 3.6–227.3) in women with serum AMH >60 pmol/L, in comparison to those with an AMH < 15 pmol/L. AMH better discriminated women with menstrual disturbance (area under ROC 0.77) from those with regular menstrual cycles than AFC (area under ROC 0.67), however the combination of the two markers increased discrimination than either measure alone (0.83; 95% CI 0.77–0.89). Serum AMH was higher in women with all three cardinal features of PCOS (menstrual disturbance, hyperandrogenism, polycystic ovarian morphology) when compared to women with none of these features (65.6 vs. 14.6 pmol/L; P < 0.0001). The odds of menstrual disturbance were increased by 10.7-fold (95% CI 2.4–47.1) in women with bilateral polycystic morphology ovaries than those with normal ovarian morphology. BMI was a stronger predictor of free androgen index (FAI) than either AMH or AFC.Conclusion: Serum AMH could serve as a useful biomarker to indicate the risk of menstrual disturbance due to PCOS. Women with higher AMH levels had increased rates o

Journal article

Prague J, voliotis M, Clarke S, Comninos A, Abbara A, Jayasena C, Roberts R, Yang L, veldhuis J, tsaneva-atanasova K, mcardle C, Dhillo Wet al., 2019, Determining the relationship between hot flushes and LH pulses in menopausal women using mathematical modelling, Journal of Clinical Endocrinology and Metabolism, Vol: 104, Pages: 3628-3636, ISSN: 0021-972X

BackgroundHypothalamic kisspeptin/neurokinin B/dynorphin (KNDy) neurones regulate LH pulsatility. It is widely accepted that the menopausal hot flush (HF) consistently synchronises with the LH pulse. This suggests that the hypothalamic KNDy neurones are implicated in generating LH pulsatility and HF. Using a modern immunoassay and mathematical modelling we investigated if the HF and LH pulse was consistently synchronised in menopausal women.MethodsEleven menopausal women (51-62yrs experiencing ≥7 HF/24hrs) attended for an 8 hour study where they self-reported HF and underwent peripheral blood sampling every 10 mins. LH pulsatility was determined using two mathematical models: blinded deconvolution analysis and Bayesian spectrum analysis. The probability that the LH pulse and HF event intervals matched was estimated using the interval distributions observed in our data.ResultsNinety-six HF were self-reported, and 82 LH pulses were identified by blinded deconvolution analysis. Using both models, the probability that the two event intervals matched was low in the majority of participants (mean P=0.24 (P=1 reflects perfect association)).InterpretationOur data challenges the widely accepted dogma that HF consistently synchronise with an LH pulse, and so has clinically important therapeutic and mechanistic implications.

Journal article

Abbara A, patel A, Hunjan T, Clarke S, Chia G, Eng P, Phylactou M, Comninos A, Lavery S, Trew G, salim R, Rai R, kelsey T, Dhillo Wet al., 2019, FSH requirements for follicle growth during controlled ovarian stimulation, Frontiers in Endocrinology, Vol: 10, ISSN: 1664-2392

Introduction: Ovarian follicle growth is a key step in the success of assisted reproductive treatment, but limited data exists to directly relate follicle growth to recombinant FSH (rFSH) dose. In this study, we aim to evaluate FSH requirements for follicular growth during controlled ovarian stimulation.Method: Single centre retrospective cohort study of 1,034 IVF cycles conducted between January 2012-January 2016 at Hammersmith Hospital IVF unit, London, UK. Median follicle size after five days of stimulation with rFSH and the proportion of antral follicles recruited were analysed in women treated with rFSH alone to induce follicular growth during IVF treatment.Results: Starting rFSH dose adjusted for body weight (iU/kg) predicted serum FSH level after 5 days of rFSH (r2=0.352, p<0.0001), median follicle size after 5 days of rFSH, and the proportion of antral follicles recruited by the end of stimulation. Day 5 median follicle size predicted median follicle size on subsequent ultrasound scans (r2=0.58-0.62; p<0.0001), and hence time to oocyte maturation trigger (r2=0.22, P<0.0001). Insufficient rFSH starting dose that required >5% dose-increase was associated with increased variability in follicle size on the day of oocyte maturation trigger, and negatively impacted the number of mature oocytes retrieved.Conclusion: Weight-adjusted rFSH dose correlates with follicular growth during ovarian stimulation. Early recruitment of follicles using a sufficient dose of rFSH from the start of stimulation was associated with reduced variability in follicle size at time of oocyte maturation trigger and an increased number of mature oocytes retrieved.

Journal article

Thurston L, Abbara A, Dhillo W, 2019, Investigation and management of subfertility, Journal of Clinical Pathology, Vol: 72, Pages: 579-587, ISSN: 1472-4146

Subfertility affects one in seven couples and is defined as the inability to conceive after 1 year of regular unprotected intercourse. This article describes the initial clinical evaluation and investigation to guide diagnosis and management. The primary assessment of subfertility is to establish the presence of ovulation, normal uterine cavity and patent fallopian tubes in women, and normal semen parameters in men. Ovulation is supported by a history of regular menstrual cycles (21–35 days) and confirmed by a serum progesterone >30 nmol/L during the luteal phase of the menstrual cycle. Common causes of anovulation include polycystic ovary syndrome (PCOS), hypothalamic amenorrhoea (HA) and premature ovarian insufficiency (POI). Tubal patency is assessed by hysterosalpingography, hystero-contrast sonography, or more invasively by laparoscopy and dye test. The presence of clinical or biochemical hyperandrogenism, serum gonadotrophins (luteinising hormone/follicle stimulating hormone) / oestradiol, pelvic ultrasound to assess ovarian morphology / antral follicle count, can help establish the cause of anovulation. Ovulation can be restored in women with PCOS using letrozole (an aromatase inhibitor), clomifene citrate (an oestrogen antagonist) or exogenous gonadotrophin administration. If available, pulsatile gonadotrophin releasing hormone therapy is the preferred option for restoring ovulation in HA. Spermatogenesis can be induced in men with hypogonadotrophic hypogonadism with exogenous gonadotrophins. Unexplained subfertility can be treated with in vitro fertilisation after 2 years of trying to conceive. Involuntary childlessness is associated with significant psychological morbidity; hence, expert assessment and prompt treatment are necessary to support such couples.

Journal article

Abbara A, Duijkers I, Ezzati M, Voors-Pette C, Romeijn C, Berman L, Fan X, Migoya E, Dhillo Set al., 2019, Effect of MVT-602, a potent kisspeptin receptor agonist, on luteinizing hormone (LH) concentrations in healthy pre-menopausal women undergoing a minimal controlled ovarian stimulation (COS) protocol, 35th Annual Meeting of the European-Society-of-Human-Reproduction-and-Embryology (ESHRE), Publisher: OXFORD UNIV PRESS, Pages: 127-128, ISSN: 0268-1161

Conference paper

Hunjan T, Abbara A, Patel A, Clarke S, Chia G, Eng P, Phylactou M, Comninos A, Lavery S, Trew G, Salim R, Rai R, Kelsey T, Dhillo Wet al., 2019, FSH requirements for follicle growth during controlled ovarian stimulation, 35th Annual Meeting of the European-Society-of-Human-Reproduction-and-Embryology (ESHRE), Publisher: OXFORD UNIV PRESS, Pages: 447-447, ISSN: 0268-1161

Conference paper

Hunjan T, Abbara A, Patel A, Clarke S, Chia G, Eng PC, Phylactou M, Cominos A, Lavery S, Trew G, Salim R, Rai R, Kelsey T, Dhillo Wet al., 2019, FSH requirements for follicle growth during controlled ovarian stimulation in IVF cycles, Publisher: WILEY, Pages: 193-194, ISSN: 1470-0328

Conference paper

Tia H, Abbara A, 2019, Clinical Translational Studies of Kisspeptin and Neurokinin B, SEMINARS IN REPRODUCTIVE MEDICINE, Vol: 37, Pages: 119-123, ISSN: 1526-8004

Journal article

Romero-Ruiz A, Avendaño MS, Dominguez F, Lozoya T, Molina-Abril H, Sangiao-Alvarellos S, Gurrea M, Lara-Chica M, Fernandez-Sanchez M, Torres-Jimenez E, Perdices-Lopez C, Abbara A, Steffani L, Calzado MA, Dhillo WS, Pellicer A, Tena-Sempere Met al., 2019, Deregulation of miR-324/KISS1/kisspeptin in early ectopic pregnancy: mechanistic findings with clinical and diagnostic implications, American Journal of Obstetrics and Gynecology, Vol: 220, Pages: 480.e1-480.e17, ISSN: 0002-9378

BACKGROUND: Ectopic pregnancy is a life-threatening condition for which novel screening tools that would enable early accurate diagnosis would improve clinical outcomes. Kisspeptins, encoded by KISS1, play an essential role in human reproduction, at least partially by regulating placental function and possibly embryo implantation. Kisspeptin levels are elevated massively in normal pregnancy and reportedly altered in various gestational pathologic diseases. Yet, the pathophysiologic role of KISS1/kisspeptin in ectopic pregnancy has not been investigated previously. OBJECTIVE: The purpose of this study was to evaluate changes of KISS1/kisspeptin levels in ectopic pregnancy and their underlaying molecular mechanisms and to ascertain the diagnostic implications of these changes. STUDY DESIGN: A total of 122 women with normal pregnancy who underwent voluntary termination of pregnancy and 84 patients who experienced tubal ectopic pregnancy were recruited. Measurements of plasma kisspeptins and KISS1 expression analyses in human embryonic/placental tissue were conducted in ectopic pregnancy and voluntary termination of pregnancy control subjects during the early gestational window (<12 weeks). Putative microRNA regulators of KISS1 were predicted in silico, followed by expression analyses of selected microRNAs and validation of repressive interactions in vitro. Circulating levels of these microRNAs were also assayed in ectopic pregnancy vs voluntary termination of pregnancy. RESULTS: Circulating kisspeptins gradually increased during the first trimester of normal pregnancy but were reduced markedly in ectopic pregnancy. This profile correlated with the expression levels of KISS1 in human embryonic/placental tissue, which increased in voluntary termination of pregnancy but remained suppressed in ectopic pregnancy. Bioinformatic predictions and expression analyses identified miR-27b-3p and miR-324-3p as putative repressors of KISS1 in human embryonic/placental tissue

Journal article

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