Moskaliuk V.D., Sorokhan V.D., Melenko
S.R.
Bukovinian
State Medical University, Ukraine
The changes of thombomodulin and von
Willebrand factor in patients with HIV-infection/AIDS
Recently, special attention of scientists focused on the role of
endothelium in the pathogenesis of HIV infection. Locally, the
endothelium forms a wall of hepatic blood capillary – sinusoid to ensure exchange
between blood and tissues. In general, endothelial lining of blood vessels of
the body is seen as an active independent body that ensures homeostasis of the
vascular wall and is an important barrier to the spread and development of
infection [4, 9].
Molecules that are produced by endothelium and are
markers of its activation and damage are in soluble form in the bloodstream [7].
They
can identify qualitative and quantitative laboratory methods. In particular, highly
sensitive tests are defined in the peripheral blood content of thrombomodulin and
von Willebrand factor levels [1, 3].
Thrombomodulin is a
surface glycoprotein of endotheliocytes that involved in the processes of blood
coagulation and fibrinolysis [12]. In
case of damage endothelial thrombomodulin released into the blood in soluble
form, and its concentration in blood correlates with the degree of endothelial
damage [5].
Von Willebrand factor is an adhesive
glycoprotein which accumulates in the secretory granules of endothelial cells
and subendothelial matrix. It regulates the initial adhesion of platelets to
subendothelial and plasma levels of coagulation factor VIII. The level of von
Willebrand factor in the blood increased by stimulation of endothelial
cytokines and in case of it damaged [1].
The aim of the study was to study the content of
these markers of endothelial dysfunction in blood of patients with HIV infection,
they change depending on the clinical stage of disease and under HAART treatments.
Patients and
methods. The study involved
127 patients with HIV infection who were on ambulatory treatment during
2008-2011 in a regional center for prevention and fight against AIDS of
Chernivtsi. Among these patients were 66 men and 61 women aged 19
to 44 years.
Among examined there were 35 (27.6%) patients
with clinical stage I, 60 (47.2%) - II, 22 (17.3%) - III, 10 (7,9%) - IV
clinical stage.
All patients were divided into two groups: I -
93 persons (47 men and 46 women) aged 19 to 44 years who did not receive HAART;
II - 34 patients (19 men and 15 women) aged 21 to 44 years who got first-line
HAART (zidovudine + lamivudine + efavirenz). These patients
were on HAART for at least 3 months.
Patients with I and II clinical stage HIV-infection/AIDS
were combined in the first study subgroup, and from III and IV – to the second subgroup.
21
representative of group II(61.8%) was in phase II clinical HIV-infection/AIDS, 9
(26.4%) – in III and 4 (11.8%) – in IV. Patients with clinical stage II HIV-infection/AIDS
made first, and from III and IV - the second subgroup II.
In serum samples of all patients with HIV
infection by ELISA quantitatively has been determined von Willebrand factor and
thrombomodulin. To identify thrombomodulin used test systems produced
by Diaclone (France), and von Willebrand factor - test kits manufactured by
Shield Diagnostics (UK). The content of von Willebrand factor calculated as a
percentage of standard samples for standard curves [3].
Statistical analysis of digital data had been
done by a computer program “Microsoft Excel 2007”, using the criterion of
Student’s and linear correlation coefficient and Pearson. The value of p
<0.05 was considered statistically significant.
Results and discussion. Established that significant changes were subjected
to all the indicators of endothelial dysfunction. In the
representatives of each subgroup thrombomodulin concentration significantly
higher than for healthy persons, for I-st and II clinical stages of HIV
infection (12,17 ± 0,38) mg/l, while III and IV - (17,38 ± 0, 40) mg/l, with
normal (4,83 ± 0,35) mg/l (p <0,02-0,005). Importantly, together with the
deepening of HIV significantly increased the concentration of this marker.
The concentration of von Willebrand factor also
changed significantly in the patients first subgroup (202,65 ± 4,33)% and the
second subgroups - (221,11 ± 2,57)%, significantly exceeding the level of
healthy individuals - (164,50 ± 6,30 )% (p <0.02). At the same time
with the progression of HIV concentration of this parameter significantly
increased (P2-1 <0.05).
Established a strong inverse correlation
between the number of T-helper cells and content thrombomodulin - r = -0,74 ...
-0,91, and between the number of T-helper cells and the concentration of von
Willebrand factor - the average inverse (r = -0,43 ... -0,68).
Elevated thrombomodulin and von Willebrand
factor in the patients apparently are the outcome of blood capillary structure
and/or increase the expression and release of these factors on endothelial
cells as the microvasculature of body tissues. Thus, the
findings confirm the hypothesis about the development of endothelial
dysfunction in HIV-infection/AIDS.
Damage to endothelial monolayer hypothetically
could be the result of pathogenetic links of HIV infection, including virus
particles passing through the endothelial barrier and the interaction of
immunocompetent cells of the vascular wall. Thus, in the
world literature there is evidence of direct infection of endothelial HIV [2, 6],
although the direct cytopathic effect of virus in endothelial cells remains to
be confirmed.
More proven is a scheme of
HIV-induced damage of endothelial cells through a cascade of inflammatory reactions,
which is also an important link in the pathogenesis of HIV infection [3]. HIV proteins
launch allocation of proinflammatory cytokines such as interleukin-8 (IL-8) and
cause endothelial apoptosis [8]. Our studies confirm these data, since
overexpression thrombomodulin and von Willebrand factor is a component of the
inflammatory response of the vascular wall. In particular, thrombomodulin
regulates blood clotting and fibrinolysis has anti-inflammatory and
cytoprotective effects, contributing to the maintenance of endothelial
integrity. As the release of thrombomodulin that may occur due to inhibition of
its formation under the action of cytokines or neutrophils-dependent
proteolytic department soluble thrombomodulin of endothelial membrane creates
conditions favorable for the development of inflammation. On the other hand,
the endothelial monolayer structure violations stimulates excretion of von
Willebrand factor, which in turn contributes not only platelet adhesion to bare
subendothelium, but adhesion of leukocytes to endothelial cells, also
contributing to the development of inflammation [12].
The idea of an important pathogenetic role of
persistent activation of endothelium in the progression of HIV infection is
confirmed also in studies of the impact of increased expression of biologically
active substances such as IL-8 and transforming growth factor β (TGF β), which have stimulating effect on the processes
neoangiogenesis [6].
Conclusions
1.
In all patients with HIV
infection significantly increases the concentration thrombomodulin and von
Willebrand factor, indicating that HIV-induced lesions of the vascular wall.
2.
The established inverse
correlation between the number of T-helper cells and of endothelial
dysfunction: the extent of progression of HIV concentration of all these
parameters significantly increased.
3.
3-month symptomatic
therapy does not affect the state of endothelium.
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