News in laboratory diagnostics of metabolic

syndrome

Prof. David Stejskal, MD, PhD, MBA, EurChem

(david.stejskal@nemsne.cz)

Dept. of Medical Chemistry and BiochemistryFaculty of Medicine and Dentistry

Palacky University, OlomoucCzech Republic

Outline

• Definition

• Pathophysiology & dg. markers

• New markers

Definition(s)

21 April 2023 3

Definition(s) - comments(Reaven sy. X, syndrome of insulin resistance)1. WHO (1998) – used esp. in research2. NCEP ATP III (2001) (National Cholesterol Education Program

expert panel and Adult Treatment Panel) – in clinical settings3. IDF (2005) (International Diabetes Federation) – in clinicsAll were different… common factors: IGT (or IR) Obesity (visceral adiposity) Hypertension (endothelial dysfunction) Dyslipidemia (atherogenic)

4. Harmonized definition (2009)4

Harmonized definition (2009)

5

Metabolic syndrome = 3 and more of the following risk factors:Central obesity Waist circumference (for EU population):

males ≥ 94 cm ( risk) ≥ 102 cm ( risk)females ≥ 80 cm ( risk) ≥ 88 cm ( risk)

Hypertriacylglycerolemia ≥ 1.7 mmol/l (or specific treatment)

HDL-cholesterol males < 1.0 mmol/l (or specific treatment)females < 1.3 mmol/l (or specific treatment)

Arterial blood pressure ≥ 130 / ≥ 85 mmHg (or specific treatment)

Fasting glycemia (IFG) ≥ 5.6 mmol/l (type II DM)

Prevalence

Positively correlates with population age and obesity

In the EU: 15 – 30% adults (depending on the definition) ca. 40% of senior citizenssuggesting that prevalence of type II DM and CV complications will sharply rise in the following decades

In the Czech Republic (productive age 24 - 65 yrs): ca. 32% of men and ca. 24% of women

In Slovakia:ca. 20% (NCEP) or 40% (IDF) of adults

6

Metabolic syndrome (MS)MS develops in time depending on:

• genetic predisposition (susceptibility)

• lifestyle factors (activity, E intake)

• age

Pathophysiology – older concept

• Insulin resistance

– hyperglycemia (and sympathetic tone)

• Visceral adiposity

– waist circumference (obesity), neck circumference

• Endothelial dysfunction

– hypertension

• Atherogenic dislipoproteinemia

– TAG, HDL8

Pathophysiology

proinflammatory prothrombotic

proatherogenic

DM II as a manifestation of MS

Type II DMType II DM insulin resistanceinsulin resistance hyperinsulinemiahyperinsulinemia visceral obesityvisceral obesityhypertensionhypertension

inflammationinflammation fibrinolysis impairmentfibrinolysis impairment prothrombotic stateprothrombotic state

dyslipidemiadyslipidemia hormonal hormonal changeschanges

Consequences of MS

(adopted from: Pelikánová. T.: Inzulinová rezistence a metabolický syndrome, 2004)

Note: patients with MS have:•8x greater DM II risk•2-3x greater CV risk•high total morbidity and mortality due to atherosclerosis and cardiovascular events as well as tumors (esp. colorectal Ca, prostate Ca, lung Ca, Ca of the uterus…)

Insulin resistance

Hyperinsulinemia

Central obesity DLP (HDL, TAG, sdLDL and postprandial lipemia)

IFG, IGT, type II DM

Proinflammatory state Hyperuricemia (CRP, TNF-α, IL-6 Essential hypertension

and adhesion molecules)

Impaired () hemocoagulation Endothelial dysfunction (PAI-1, fibrinogen) Microalbuminuria

Accelerated atherosclerosis

Tumors, non-alcoholic steatohepatitis (NASH), polycystic ovaries syndrome (PCOS)

Insulin resistance (IR)

• Defined as decreased biological response* to normal conc. of insulin

• IR leads to endothelial dysfunction and systemic inflammation

*Biological response is typically referred to in terms of blood glucose level, but other effects of insulin (lipid and protein metabolism) should also be considered

Dyslipoproteinemia

Typical MS-phenotype:

• HDL and apo A• LPL activity, HL and CETP activity• HDL2/HDL3 ratio

• TAG (total and VLDL 1) and FFA• TAG (apo CIII)-rich LP remnants• postprandial lipemia• small dense LDL (LDL3) and apoB100

• LP modification (glycation, oxidation)•TC and LDL may be normal or

Superiority of Apo B over LDL

source: www.bhlinc.com

prevalence of large, buoyant LDL (lbLDL) vs. more atherogenic small, dense LDL (sdLDL)

source: Clin Lipidol 2011

Hypertension in MS

„High normal pressure“ (i.e. ≥ 130/85 mm Hg) already is a risk factorTreatment: antihypertensives

•ACEi and AT1B– advantageous due to interference with the RAAS system

•alphaB and CaB– also preferable because they are metabolically indifferent

•BB– indispensable in patients with concurrent ischemic CHD

(they decrease CV risk)

•Diuretics– only in small doses, which have little -ve metabolic effects

(increase insulin sensitivity when combined with ACEi)

Obesity

Quetelet´s „body mass index“ (BMI)

BMI = body mass (kg) / body height2 (m2)

BMI does not work in low and high age groups and in athletes with a developed musculature.

BMI interpretation obesity grade20 – 24.99 Normal body mass25 – 29.99 Overweight I30 – 39.99 Obesity II> 40 Morbid obesity III

Obesity

• Genetic factors– 23 obesity-associated genes have been

identified until recently – presumably > 40% of primary obesity

cases have a genetic background

• Lifestyle– genetics is the gun, lifestyle is the trigger– consumption of E-rich foods (polyphagia)

inadequate to physical activity

Obesity

• Endocrine diseases associated with obesity:– Hypothyreosis– Cushing syndrome– Hyperprolactinemia

• GH deficiency and hypogonadism• adiposity but not necessarily obesity

– Diabetes mellitus (type II)

Obesity

• localization of fat tissue accumulation!

• abdominal adiposity– may be indirectly determined using the

waist to hip ratio

• visceral fat is metabolically active – releases FFA, which:

• are transported to the liver and peripheral tissues

• induce insulin resistance (and in concert with LPL/HL activity result in dislipoproteinemia in obese patients)

Significance of the visceral fat

According to J. P. Despres

Waist circumference is a good predictor of visceral fat, fat around liver..!!

Laboratory tests - classicSerum (plasma):

• intact proinsulin best marker of IR• C-peptide• TAG• hsCRP (ultrasensitive)• Plasma glucose (or HbA1c)• Uric acid

• NEW MARKERS• News

– Adipokine expression in peripheral leukocytes or adipose tissue

New markers of MetSy

• Adipovascular axis– adipose tissue hormones (adipokines) have

a direct effect on the vascular wall and endothelium

• control energy metabolism

• involved in atherosclerosis…

– determination of adipokines and selected liver peptides or proteins

– extrapolation from animals and use in clinical practice?

Definition of endocrine organ• Secretory proteome contains at least 15,000 genes (it

is only those which have the mRNA after transcription of the signal sequence and is therefore secreted via the classic pathway). Among them, there are hundreds or thousands of proteins that come from cells of non-classic way without the assistance of a signal sequence

• There is not a cell or tissue in the human body which would not produce any protein, including regulatory

 

• It is likely that each tissue is an endocrinally active and the whole then can be considered an endocrine organ

New concept

• Binder as an endocrine organ

• Skin as an endocrine organ

• Skelet

• Muscle as an endocrine organ

• Adipose tissue as an endocrine organ (the subject of our interest ) …

Adipose tissue as an endocrine organ

• White adipose tissue (WAT) adipocytes, preadipocytes, "non- adipose" macrophages, stromal cells, endothelial cells, fibroblasts, leukocytes. This composition defines the fatty tissue as an important mediator of metabolic and inflammatory processes

• 1993 Discovery of secretion of TNF-a?

• 1994 Discovery of first adipokines in the true sence of the word - slimness hormone LEPTIN (deficit led to extreme obesity).

• Gradually, it was found that no adipokines secreted not only adipocytes or fat tissues. There are many definitions • inflammatory/non-inflammatory; • adipokines similar to hormones/cytokines/chemokines; • the new division at sensu stricto/sensu lato and adipokines helpful to humans and harmful (set in contemporary evolutionary and geo-economic situation

Metabolic syndrome (cluster of cardiovascular risk factors -obesity, DM II, dyslipidemia, hypertension..)

• If we add to the knowledge of the most well-known effects of adipokines

• Direct influence of TRG (fats)č steatosis of organs (liver, muscle)

+• Lipotoxic effect of FA for most tissues in the

body (incl. pancreas)

The cause of metabolic syndrome (Metsy) is now clearer

Selected adipokinesLeptin – disc 1994• (via leptin receptor) regulates () appetite and () E expenditure• high leptin in obese individuals does not lead to decreased appetite (leptin resistance)

Adiponectin• production in obese, IR, endotelial dysfunction, CHD and MS patients• decreases endothelial expression of adh. molecules, ROS, gluconeogenesis, Ma activation and foam cell accumulation• increases glucose utilization and skeletal muscle FA oxidation, antidiab, antiats ef

FGF-21• marker and independent positive risk factor of MS and type II DM• produced by the liver and adipose tissue (correlates positively with fat mass)• regulates insulin-independent transport of glucose into cells• antidiabetic effect (leads to glucose uptake by adipocytes by GLUT-1 expression)• admin. of FGF-21 leads to glycemia and HDL (comparably to insulin)

A-FABP (Adipocyte Fatty Acid Binding Protein)• best parameter and predictor of MS, most dangerous adipokin, connection with CV mortality and morbidity• regulates LP ( lipolysis) and glucose metabolism• modulates proinflammatory cytokine production and CHE accumulation in Ma• Macrophage A-FABP expression is by oxLDL and by statins

Omentin-1 is another new adipokine with anti-inflammatory effects, which affects the formation of AMI. Individuals with AMI had lower omentin-1 in serum and regular exercise leads to an increase of omentin-1 in serum and have decreased inflammation.

Omentin-1 had 97.7 sensitivity and 100% specificity, cut-off 207 mg/l

21 April 2023 medical biochemistry lecture 29

A „new“ syndrome associated with A „new“ syndrome associated with MetSy: MetSy: Obesity hypoventilation syndromeObesity hypoventilation syndrome

• A number of unknown consequences

• Excessive production of carbon dioxide CO2 leads to hypercapnia

• OHS is considered as a disease with multiorgan diurnal hypercapnia and hypoxia, leading to many metabolic disturbances

• New: this is a cluster of MetSy (part of MetSy)

New risk factors: New risk factors: dermatological patientsdermatological patients

• Psoriasis, systematic LE, PCOS, Psoriasis, systematic LE, PCOS, androgenic alopecia, lichen androgenic alopecia, lichen planusplanus

New risk factors: New risk factors: The relationship between MetSy and carcinomas, ie CaP (BPH)

• Obesity and fat intake is associated with risk of prostate cancer (CaP) and BPH.

• In a pilot US study (2005-2012) on 199 people with CaP it was found that most were overweight with increased trg and reduced HDL cholesterol.

New risk factor or part or cluster: NAFLD• NAFLD has a high prevalence (33%),

manifested variously (steatosis, fibrosis, cirrhosis, hepatocellular carcinoma).

• It is associated with insulin resistance, lipotoxicity and markers of MetSy

• Insulin resistance leads to the accumulation of fat (trg) in the liver increased with FFA, there is inflammation and stress in the endoplasmatic reticulum.

• Visceral fat in the liver is considered the most risky for cardiovascular diseases.

• Men usually have a deficit of free testosterone in blood.

Neck circumference - a new risk factor• Circumference of the neck is

connected to the CV risk

• 2012-2015 20 studies in Asia

• A cut-off was determined for the presence of MetSy – for men: 39 cm – for women: 33 cm

GHDA - a new critical point in MetSy• GHDA - growth hormone deficiency in

adults is associated with a high risk of MetSy. Ghrelin induces its release (ghrelin also decreases with age as GH).

• GHDA mean- high waist circumference, low HDL, higher trg, hypertension, it is MetSy And Ghrelin deficiency.

• Treatment: rhGH (improves the parameters of MetSy and the quality of life, but there is no data in subjects over 80 years old).

• New form of therapy: Ghrelin administration?

Conclusion

• Some basic clusters of MetSy are gradually– Expanded– Reduced

• so we need to take into account the latest scientific information and translational research

21 April 2023 medical biochemistry lecture 36

MetSy is a polygenic and multifactorial disease with a dominant and

progressive prevalence worldwide.

Laboratory medicine is one of the areas which can use a variety of etiopathogenetic factors in

experimental designs or complement such designs.

From their interlinking and connecting with other clinical symptoms of the underlying

disease or its complications arises a somewhat modified picture of obesity, which suggests further possibilities for its treatment and

prevention.