Journal of Clinical Medicine Article Independent Impact of Gynoid Fat Distribution and Free Testosterone on Circulating Levels of N-Terminal Pro-Brain Natriuretic Peptide (NT-proBNP) in Humans Małgorzata Chlabicz 1,2 , Jacek Jamiołkowski 1, Marlena Paniczko 1, Paweł Sowa 1, Magda Łapi ´nska 1, Małgorzata Szpakowicz 1, Natalia Jurczuk 1, Marcin Kondraciuk 1, Andrzej Raczkowski 1, Emilia Sawicka 1,3 and Karol Adam Kami ´nski 1,3,* 1 Department of Population Medicine and Civilization Diseases Prevention, Medical University of Bialystok, 15-269 Bialystok, Poland; [email protected] (M.C.); [email protected] (J.J.); [email protected] (M.P.); [email protected] (P.S.); [email protected] (M.Ł.); [email protected] (M.S.); [email protected] (N.J.); [email protected] (M.K.); [email protected] (A.R.); [email protected] (E.S.) 2 Department of Invasive Cardiology, Teaching University Hospital of Bialystok, 15-276 Bialystok, Poland 3 Department of Cardiology, Teaching University Hospital of Bialystok, 15-276 Bialystok, Poland * Correspondence: fi[email protected]; Tel.: +48-856-865-371 Received: 15 December 2019; Accepted: 24 December 2019; Published: 27 December 2019 Abstract: Background: Natriuretic peptides (NPs), including brain natriuretic peptide (BNP), are neurohormones involved in the regulation of water-sodium balance and the maintenance of cardiovascular homeostasis. A higher concentration of NPs is observed in females, but the mechanism behind this difference has not been fully elucidated. Methods: Randomly chosen 255 volunteers from the general population were examined. Overall, 196 people without severe cardiovascular disease were included (mean age 48 years, 35.7% male). A comprehensive assessment was performed, including anthropometric measurements, N-terminal pro-brain natriuretic peptide (NT-proBNP), total testosterone (TT) and sex hormone-binding globulin (SHBG) concentration, transthoracic echocardiography (ECHO), and body composition analysis by direct dual-energy X-ray absorptiometry (DEXA). The univariate analysis adjusted by the known affecting factors determined which measurements were independently associated with NT-proBNP concentration. Results: NT-proBNP concentration was positively associated with gynoid fat mass, gynoid/total fat (G/TF) mass index, SHBG and negatively with android/gynoid (A/G) fat mass index, TT and calculated free testosterone (CFT) concentrations. Furthermore, body composition parameters remained independently associated with NT-proBNP levels even after adjusting for CFT and SHBG. Conclusion: In the population without severe cardiovascular disease, the NT-proBNP concentration is independently associated with lower availability of testosterone and higher gynoid fat distribution, which may explain higher NPs levels in females. Keywords: natriuretic peptide; gynoid fat tissue; sex; population studies 1. Introduction Natriuretic peptides (NPs), including brain natriuretic peptide (BNP), are neurohormones involved in the regulation of water-sodium balance and maintenance of cardiovascular homeostasis. They exert cardioprotective effects by promoting vasodilatation, natriuresis and inhibit fibrosis counteracting the effects of the renin-angiotensin-aldosterone system. They are largely secreted by the myocardium in J. Clin. Med. 2020, 9, 74; doi:10.3390/jcm9010074 www.mdpi.com/journal/jcm J. Clin. Med. 2020, 9, x FOR PEER REVIEW 2 of 15 J. Clin. Med. 2020, 9, 74 2 of 13 pro-brain natriuretic peptide (NT-proBNP) is the physiologically inactive 1–76 amino acid fragment, which is secreted with mature 32-amino acid BNP after cleavage from the prohormone [3–5]. The measurementresponse of to pathologically the increased wall elevated stress, plasma ischemia level and of hypertrophyBNP and its co-released [1,2]. N-terminal peptide pro-brain NT-proBNP natriuretic with apeptide longer plasma (NT-proBNP) half-life is allows the physiologically diagnosing cardiovascular inactive 1–76 diseases, amino acidespecially fragment, heart which failure is (HF) secreted [2,6]. withA higher mature concentration 32-amino acid of NPs BNP is afterobserved cleavage in older from people, the prohormone females, and [3– 5in]. individuals The measurement with of lowerpathologically glomerular filtration elevated rate plasma (GFR) level or atrial of BNP fibrillation and its co-released(AF) while peptidelower in NT-proBNPobese people with [7–11]. a longer The mechanismplasma half-life behind allows these diagnosing differences cardiovascular has not been diseases,fully elucidated. especially A heartprior failurestudy suggested (HF) [2,6]. that A higher BNP concentrationlevels were inversely of NPs is correlated observed inwith older lean people, body females,mass [9], and or inNT-proBNP individuals concentration with lower glomerular was inverselyfiltration associated rate (GFR) with or visceral atrial fibrillation adipose tissue (AF) whilein both lower sexes in and obese with people subcutaneous [7–11]. The adipose mechanism tissue behind only inthese women differences [12]. It has has not not been been fully established elucidated. whether A prior there study is suggesteda link between that BNP NPs levels concentration were inversely and regionalcorrelated fat with distribution. lean body Therefore, mass [9], or we NT-proBNP have analyzed concentration this relationship was inversely further associated extending with the visceral analysisadipose to the tissue effect in of both the sexestestosterone and with bioavailability subcutaneous and adipose sex hormone-binding tissue only in women globulin [12]. It(SHBG), has not been becauseestablished of the established whether there influence is a link of gonadal between st NPseroids concentration on body composition and regional [13]. fat distribution.We hypothesized Therefore, that wethe haverelation analyzed between this relationshipplasma NT-proBNP furtherextending concentration the analysis and differences to the effect in ofregional the testosterone fat distributionbioavailability could give and an sex insight hormone-binding into the regulation globulin of (SHBG),expression because of NPs of levels the established in the population influence of samplegonadal without steroids severe oncardiovascular body composition disease. [13]. We hypothesized that the relation between plasma NT-proBNP concentration and differences in regional fat distribution could give an insight into the 2. Materialsregulation and of Methods expression of NPs levels in the population sample without severe cardiovascular disease. 2. Materials and Methods 2.1. Study Population The2.1. Studystudy Populationwas conducted in 2017–2018 in a representative sample of area residents aged between 20The to study77. According was conducted to the in2017 2017–2018 Central in Statistical a representative Office data, sample the of number area residents of residents aged between in Bialystok20 to was 77. According297,300. Randomly to the 2017 selected Central resident Statisticals (600) Offi cefrom data, the the mayor’s number office of residents database in were Bialystok invitedwas to 297,300.participate Randomly in the study. selected Three residents people (600)from fromthe random the mayor’s group o ffidiedce databasebefore receiving were invited an to invitation,participate 255 individuals in the study. responded Three people and were from ex theamined. random Due group to the died history before of receiving ischaemic an heart invitation, disease255 (IHD), individuals previously responded diagnosed and wereHF, cardiac examined. surgery, Due valvular to the history heart ofdisease, ischaemic AF or heart reduced disease left (IHD), ventricularpreviously ejection diagnosed fraction HF, below cardiac 50% surgery, in the valvular current heart echocardiography, disease, AF or reduced 59 people left ventricularwere further ejection excludedfraction from below the research 50% in the group. current As echocardiography,a result, 196 people 59 (126 people wome weren and further 70 men) excluded were fromincluded the research in the studygroup. (Figure As a result,1). 196 people (126 women and 70 men) were included in the study (Figure1). Figure 1. Analyzed cohort of 196 included individuals. Figure 1. Analyzed cohort of 196 included individuals. J. Clin. Med. 2020, 9, 74 3 of 13 2.2. Data Collection and Assays The subjects’ medical records were obtained by the questionnaires filled at the time of entry. All study participants underwent a laboratory assessment and physical examination. Peripheral intravenous fasting blood samples were collected in the morning on a visit day. Plasma was stored at 80 C until analyzed. For analysis, samples were thawed at 37 C, prepared, and analyzed − ◦ ◦ immediately. The concentration of NT-proBNP, total testosterone (TT) and sex hormone-binding globulin (SHBG) were determined by the electrochemiluminescence method on the Cobas e411 from ROCHE. The free testosterone (FT) was calculated (CFT) by published methods described by Ly and Handelsman [14] with the use of the following formulas: Model 1 EFT-lo = 6.593 + 19.304 TT + 0.056 SHBG 0.0959 TT SHBG, (1) − − × Model 2 EFT-hi = 52.65 + 24.4 TT 0.704 SHBG 0.0782 TT SHBG 0.0584 TT2, (2) − − × − Model 1 was used for low testosterone <5 nmol/L, model 2 for high testosterone 5 nmol/ L (with ≥ TT and SHBG in nmol/L). The negative values of CFT were changed to 0. The comprehensive assessment was performed: the anthropometric measurements including height, weight, circumferences of waist, hips and the measurement