02 октября 2016г.
The aim of the study was to investigate the relationship between FGF-23, Klotho serum concentration (sFGF-23, sKlotho) changes and diffuse arterial stiffness, calcification intensity and myocardial remodelling in patients with different stages of Chronic Kidney Disease (CKD).
Materials and Methods:. 130 patients with CKD 1-5D stage were included in the study : 30-with chronic glomerulonephritis, 23-tubulointerstitial nephritis 28-hypertensive nephrosclerosis, 27-diabet mellitus (66 men and 64 women, aged 20-65 years, mean age at enrollment was 41 ± 6,7 years).
The control group consisted of 40 volunteers the same average age and sex .sFGF-23 levels (Human FGF-23 ELISA kit using monoclonal antibodies to the full FGF-23 molecule), sKlotho (Human alpha-Kl ELISA using anti-Klotho antibodies) were applied in these patients. Echocardiography was performed to patients with arterial hypertension and left ventricular mass index (LVMI) was calculated. The state of blood flow in the heart and large vessels (Doppler ultrasound Echocardiography), pulse wave velocity (Sphygmakor), calcifications scors (echocardiography, radiography of abdominal aorta by Kauppila method) and vascular wall functional ability (augmentation indices by Sphygmakor) were studied.
Results: A strong direct correlation [r = 0,731, p<0,01] was established between glomerular filtration rate (GFR) and sFGF-23 concentration, inverse correlations [r = - 0,489, p <0,01] were established between GFR and sKlotho. When comparing sFGF-23 and sKlotho levels in patients with different CKD stages was found sFGF-23 levels increased and sKlotho levels decreased, as increasing CKD severity, ahead of serum phosphorus and PTH levels elevating, starting at CKD 3a stage, whereas hyperphosphatemia and increased PTH levels were fixed started in CKD-4 -5 stage. At the same time, sKlotho concentrations reducing in patients with CKD progression were in inverse correlation with serum levels of phosphorus and PTH.
In addition, it was found the feedback between enhanced sFGF-23 levels with increased left ventricular mass [ r = 0,452; p <0,05].In hypertensive patients (n = 98) this connection was extremely expressed [ r = 0,850 p<0,05].
We also established the strong straight relationship of sFGF-23 serum concentrations [r = 0,492,p<0,01] and the reverse relationship of sKlotho levels [r = -0,537; p<0,01] with time of pulse valve reflection (Sphygmacor).
In studied patients reduced sKlotho level have been clearly associated with a higher frequency of calcificat identification in the heart valves ( Echocardiography) and large arteries (abdominal aorta) [r =-0,525;p<0,01 and r = -0,684;p<0.01 respectively].
Reduced sKlotho has been also associated with a concentric remodeling of the myocardium [r =-0,445 p<0,01 and r = -0,567 p<0.01 respectively].
Conclusion. It was found the clear link between increased sFGF-23 and decreased Klotho as increasing CKD severity, and diffuse arterial stiffness and calcification, myocardial remodelling independent of traditional risk factors.
Key words: chronic kidney disease, fibroblast grows factor-23 (FGF-23), Klotho, ectopic calcification
Introduction. Chronic renal failure (chronic kidney disease - CKD stages 3-5D) spreads widely in the population (10-15% of the population), is characterized by a high rate of cardiovascular events (CVE) [1-3], the risk of which, including young people, increases 100 and more times [4].
In the genesis of CVE in CKD many mechanisms have a value. Among them, in recent years the dysfunction of morphogenetic proteins (FGF-23 and Klotho) plays а growing role. According to Gutierrez O.M. et al. [5], high levels of FGF-23 correlate with an increase in the left ventricular mass index (LVMI). Klotho gene damage in experimental mice causes an ectopic calcification, pathological fractures, premature aging [6,7]. On the other hand, the circulating form of Klotho protein (sKlotho) can function as a humoral factor that protects cardiovascular system [8,9]. Overexpression of sKlotho provides both renal and cardiovascular protection [9, 10]. There is a hypothesis basis on literature date about its impact on the process of arteries and heart valves calcification in patients with CKD [4].
Most studies of morphogenetic proteins were carried out on a dialysis population or in experimental models and there are not enough conclusive data about the role of FGF-23 and sKlotho in cardiorenal relationships in patients with early stages of CKD. At the same time, an understanding of mechanisms of early cardiovascular complications in patients with CKD is essential to develop new therapeutic strategies.
The aim of the study was to investigate the relationships between FGF-23, Klotho, serum concentration (sFGF-23, sKlotho) changes and diffuse arterial stiffness and calcification intensity in patients with different stages of Chronic Kidney Disease (CKD)
Methods. 130 patients with CKD 1-5D stage were included in the study : 30-with chronic glomerulonephritis, 23-tubulointerstitial nephritis 28-hypertensive nephrosclerosis, 27-diabet mellitus (66 men and 64 women, aged 20-65 years, mean age at enrollment was 41 ± 6,7 years) fig.1.
The control group consisted of 40 volunteers the same average age and sex . sFGF-23 levels
(Human FGF-23 ELISA kit using monoclonal antibodies to the full FGF-23 molecule), sKlotho
(Human alpha-Kl ELISA using anti-Klotho antibodies) were applied in these patients. Echocardiography was performed to patients with arterial hypertension and left ventricular mass index
(LVMI) was calculated. The state
of blood flow in the heart and large vessels (Doppler ultrasound Echocardiography), pulse wave velocity (Sphygmakor),
calcifications scors
(echocardiography, radiography of abdominal aorta by Kauppila method) and vascular wall functional ability (augmentation indices by Sphygmakor) were studied.
. CKD stage was determined according to the criteria NKF KDOQI Guidelines (2002), with
GFR calculated
by
the equation CKD-MDRD
[2].
The criteria do not include patients in the study were the presence of nephritis activity,
serious infectious complications at
the
study period,
heart failure
III-IV
stages by NYHA, maligns. All patients were performed screening clinical examination,
including PTH, Ca and P serum
levels determination.
sFGF-23 levels (Human FGF-23 ELISA kit using monoclonal antibodies to the full FGF-
23 molecule), sKlotho
(Human alpha-Kl ELISA using anti-Klotho antibodies) were applied in
these patients. Echocardiography according to a standard protocol was performed to patients
with arterial hypertension and left ventricular mass index (LVMI) was calculated. The state of blood
flow in the heart and large vessels
(Doppler ultrasound Echocardiography), pulse wave
velocity (Sphygmakor), calcifications
scors (echocardiography, radiography of abdominal aorta by Kauppila method)
and vascular wall functional ability (augmentation indices by Sphygmakor) were studied.
For statistical analysis it was used SPSS software for Windows
17 with performance of
correlation analysis,
regression analysis with
charting.
Results. Strong direct correlation
[r=0,731, p<0,01] was established between stage of CKD by
MDRD and sFGF-23 concentration (fig.2), inverse correlations
[r= - 0,489, p <0,01]
and [r=- 0,510, p<0,01]
were established between
stage of CKD and sKlotho(fig.3).
When comparing sFGF-23 levels in patients with different CKD stages was found sFGF-23 levels increases with decreasing GFR ahead of serum phosphorus and PTH levels elevating,
starting at CKD 3a stage, whereas hyperphosphatemia and increased PTH levels were started in
CKD-4 -5 stage (fig.4,5).
We established the strong straight relationship of FGF-23 serum levels [r =0,492,p<0,01] and the reverse relationship of sKlotho levels [r = -0,537;
p<0,01] with time of pulse
valve reflection (Sphygmakor)
fig. 6,7
In addition, it was found the feedback between enhanced FGF-23 serum levels with increased
left ventricular mass ( r=0,452; p <0,05).
In hypertensive patients
(n =
98) this connection was extremely expressed ( r=0,750
p<0,01).
In studied patients reduced sKlotho levels have been clearly associated with a higher frequency of stiffness and calcificat identification in the heart valves (Echocardiography) [mitral
valve r=-0,492 p<0,01 and r=- 0,487 p<0,01, respectively ] and large arteries (abdominal aorta) [sKloto
r =-0,525;p<0,01.] fig.8
Reduced sKlotho
levels have been also connected with a concentric remodeling of the
myocardium
[r =-0,445 p<0,01 ].
Discussion
Our results
confirm experimentally established fact that
morphogenetic proteins - sFGF-23, sKlotho are earlier than
PTH and phosphorus, markers of CKD progression and
associated with cardiovascular
complications [4,5,7].
Their changes began from
stage 3a of CKD and increased
as
worsening renal
failure in association
with the progression of
extra bone calcification and
remodeling of heart and
vessels.
Under the conditions of active nephron
mass reduction and decreasing of nephrons receptor to FGF-23 (FGFRI) in kidney
with an increase of sFGf-23 levels its effect can spread to
any other organs expressing FGFRI (for example - on the myocardium). In a number of fairly large observational studies have directly been shown
that the increase of sFGF-23 results in
remodeling of the heart and blood vessels [11,12] at the same time - regardless of the serum levels
of phosphorus, which
in most patients was
within the normal range [13].
According to the literature, in transgenic mice with increased expression of sKlotho
in CKD combined with adequate phosphaturia, better functional ability of the kidneys and
significantly lower degree of calcification compared with wild-type mice with CKD and reduce
production of sKlotho [9]. Moreover, the favorable effect on vascular calcification of sKlotho was expressed in a greater extent than its effect on renal function and phosphaturia, that
associated with a direct effect of sKlotho
to the blood vessels.
Conclusion. It our study it was found the clear link between increased FGF-23 and decreased
Klotho as increasing CKD severity, and diffuse arterial stiffness and calcification, myocardial
remodelling independent of traditional
risk factors.
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