Second-Trimester IL-15 and IL-18 Levels in the Amniotic Fluid of

Second-Trimester IL-15 and IL-18 Levels in the Amniotic Fluid of

original papers
Adv Clin Exp Med 2012, 21, 2, 201–205
ISSN 1899–5276
© Copyright by Wroclaw Medical University
Dominika Klimkiewicz-Blok1, Jerzy Florjański1, Jerzy Zalewski2, Radosław Blok3
Second-Trimester IL-15 and IL-18 Levels
in the Amniotic Fluid of Fetuses with Normal Karyotypes
and with Chromosome Abnormalities*
Stężenie IL-15 i IL-18 w płynie owodniowym w drugim trymestrze ciąży
u płodów z prawidłowym kariotypem i aberracjami chromosomowymi
Second Department of Gynecology, Obstetrics and Neonatology, Wroclaw Medical University, Wrocław,
Poland
2
Department of Gynecology and Obstetrics, Division of Public Health, Wroclaw Medical University, Wrocław,
Poland
3
First Department of Gynecology and Obstetrics, Wroclaw Medical University, Wrocław, Poland
1
Abstract
Background. Little is known about the behavior of interleukin 15 (IL-15) and 18 (IL-18) in the amniotic fluid in
the second trimester of gestations complicated by chromosomal defects in the fetus. Likewise, it has not yet been
established whether a fetus with chromosome abnormalities creates its immunity mechanisms in the same way as
a fetus with a normal karyotype.
Objectives. The aim of this work was to assess the concentration of IL-15 and IL-18 in the amniotic fluid in the
second trimester of gestation in fetuses with normal karyotypes and with chromosome abnormalities.
Material and Methods. The material consisted of 51 samples of amniotic fluid obtained from genetic amniocenteses carried out between the 15th and the 19th weeks of gestation. On the basis of cytogenetic screening, two groups
were singled out: Group I – 45 fetuses with normal karyotypes, and Group II – 6 fetuses with abnormal karyotypes.
The concentrations of IL-15 and IL-18 in the amniotic fluid were assessed with ready-made assays and analyzed,
and the results from both groups were compared.
Results. The differences between the IL-15 levels in the amniotic fluid from Groups I and II proved to be statistically
insignificant (p = 0.054). However, the average IL-18 levels in the amniotic fluid of the fetuses with normal karyotypes
were significantly higher than in the amniotic fluid of the fetuses with chromosome abnormalities (p = 0.032).
Conclusions. Some defense mechanisms in the second trimester of gestation in fetuses with chromosome abnormalities may develop in a different way than in fetuses with normal karyotypes (Adv Clin Exp Med 2012, 21, 2,
201–205).
Key words: interleukin 15, interleukin 18, amniotic fluid, chromosome aberration.
Streszczenie
Wprowadzenie. Niewiele wiadomo o zachowaniu się interleukiny 15 (IL-15) i 18 (IL-18) w płynie owodniowym
w II trymestrze ciąż powikłanych aberracjami chromosomowymi u płodu. Do tej pory nie rozstrzygnięto także, czy
u płodów z aberracjami chromosomowymi tworzenie mechanizmów odporności przebiega tak samo jak u płodów
z prawidłowym kariotypem.
Cel pracy. Ocena stężenia IL-15 i IL-18 w płynie owodniowym w II trymestrze ciąży u płodów z prawidłowym
kariotypem i aberracjami chromosomowymi.
Materiał i metody. Materiał obejmował 51 próbek płynu owodniowego uzyskanego na drodze amniocentez genetycznych wykonywanych między 15. a 19. tygodniem ciąży. Na podstawie badania cytogenetycznego wyodrębniono dwie grupy: grupa I – 45 płodów z prawidłowym kariotypem i grupa II – 6 płodów z nieprawidłowym kariotypem. Stężenia IL-15 i IL-18 w płynie owodniowym oznaczono za pomocą gotowych testów, a uzyskane z obu grup
wyniki porównano.
*This study was carried out with the support of a grant from Wroclaw Medical University.
202
D. Klimkiewicz-Blok et al.
Wyniki. Różnice między stężeniami IL-15 w płynie owodniowym w grupach I i II okazały się nieistotne statystycznie (p = 0,054). Średnie stężenia IL-18 w płynie owodniowym były znamiennie większe u płodów z prawidłowym
kariotypem niż u płodów z aberracjami chromosomowymi (p = 0,032).
Wnioski. Niektóre mechanizmy obronne w II trymestrze ciąży u płodów z aberracjami chromosomowymi mogą
rozwijać się odmiennie niż u płodów z prawidłowym kariotypem (Adv Clin Exp Med 2012, 2, 201–205).
Słowa kluczowe: interleukina 15, interleukina 18, płyn owodniowy, aberracje chromosomowe.
The basis for non-invasive prenatal diagnoses
evaluating the risk of chromosome abnormalities
appearing in fetuses is ultrasound examination,
such as measurement of the fetus’s nuchal translucency [1], the presence or absence of fetal nasal
bones [2, 3], measurement of the length of the fetal
nasal bones [4], measurement of the frontomaxillary facial angle [5], measurement of the length
of the fetus’s ears [6] and assessment of Doppler
blood flow in the ductus venosus [7, 8]. The ultrasound markers are usually tested between the 11th
and 14th weeks of gestation, and are analyzed along
with the mother’s age, the pregnancy-associated
plasma protein A (PAPP-A) concentration in their
blood, inhibin A, free estriol and free β-hCG, to
obtain a precise evaluation of the risk of chromosome abnormalities in the fetus [9, 10]. In cases
where there is a high risk of defects appearing in
the fetus, the pregnant women are qualified for
invasive methods: amniocentesis and cytogenetic
screening of the amniotic fluid.
To date there is insufficient information about
the concentration of interleukin 15 (IL-15) and
interleukin 18 (IL-18) in the amniotic fluid in
the second trimester of gestations complicated by
chromosomal defects in the fetus. Likewise, little is
known about the development of defense mechanisms in the second trimester of gestation in such
fetuses. The authors of the current study were curious as to whether immune mechanisms are formed
in the same way both in fetuses with chromosome
abnormalities and in fetuses with normal karyotypes. This question has not yet been clarified in
the available literature.
The aim of this work was to evaluate the concentration of IL-15 and IL-18 in the amniotic fluid
in the second trimester of gestation in fetuses with
normal karyotypes and in those with chromosome
abnormalities.
Material and Methods
The clinical material consisted of 51 samples
of amniotic fluid obtained from amniotic fluid
tests of pregnant women being treated at Wroclaw
Medical University’s Clinic for Fetal Development
Disorders (Wrocław, Poland) from 2004 to 2006.
The amniocenteses were carried out between the 15th and 19th weeks of gestation.
The ages of the pregnant women ranged from 24 to
46 years (average age: 37.47 years). They had been
qualified for the test on the basis of their age (over
35) and an aggravated risk of defect in the fetus indicated in biochemical tests of the mother’s blood,
ultrasound screening or high-risk genetic history.
The amniotic fluid was tested at the Wroclaw
Medical University Department of Genetics in
order to ascertain the karyotypes of the examined
fetuses. On the basis of the cytogenetic screening,
two groups were identified:
– Group I: 45 fetuses with normal karyotypes;
– Group II: 6 fetuses with abnormal karyotypes (including 5 fetuses with trisomy 21 and
1 with karyotype 45,X).
Samples of the amniotic fluid were centrifuged
at the speed of 3000 rotations per minute for 10
minutes, and then were refrigerated at a temperature of –82o Celsius until the measurements were
made. The concentrations of IL-15 and IL-18 in the
amniotic fluid were assayed by the ELISA method
using a ready-made kit (R&D Systems, Inc., Minneapolis, USA). The sensitivity of the method
was > 2 pg/ml. The value of the absorbance was
measured at λ = 450 nm. The Shapiro-Wilk test
showed no reason to reject the normal distribution hypothesis for either group. The calculations
were performed using STATISTICA 8.0 software
(StatSoft, Inc.). The values of the IL-15 and IL-18
concentrations in both groups were compared using the Student t test.
Results
The analysis of IL-15 and IL-18 levels in the
amniotic fluid in the second trimester of pregnancy in the examined groups is presented in Tables
1 and 2.
As can be seen in Table 1, the difference between the average concentration of IL-15 in
Groups I and II borders on statistical significance
(p = 0.054). As Table 2 shows, the average concentration of IL-18 was significantly higher in fetuses
with normal karyotypes than in fetuses with chromosome abnormalities (p = 0.032).
203
IL-15 and IL-18 in Amniotic Fluid in Normal and Pathological Pregnancies
Table 1. The concentration of IL-15 in the amniotic fluid in the second trimester of pregnancy in fetuses with normal
(Group I) and abnormal (Group II) karyotypes
Tabela 1. Stężenie IL-15 w płynie owodniowym w drugim trymestrze ciąży u płodów z prawidłowym (grupa I)
i nieprawidłowym kariotypem (grupa II)
Concentration of IL-15
(Stężenie IL-15)
pg/ml
Minimum value
(Wartość minimalna)
Maximum Value
(Wartość maksymalna)
Median
(Mediana)
Standard deviation
(Odchylenie
standardowe)
Group I n = 45
(Grupa I)
2.31
15.87
5.73
3.24
Group II n = 6
(Grupa II)
1.64
17.70
8.07
6.0
p
0.054
Table 2. Concentration of IL-18 in the amniotic fluid in the second trimester of pregnancy in fetuses with normal (Group I)
and abnormal (Group II) karyotypes
Tabela 2. Stężenie IL-18 w płynie owodniowym w drugim trymestrze ciąży u płodów z prawidłowym (grupa I)
i nieprawidłowym kariotypem (grupa II)
Concentration of IL-15
(Stężenie IL-15)
pg/ml
Minimum value
(Wartość minimalna)
Maximum Value
(Wartość maksymalna)
Median
(Mediana)
Standard deviation
(Odchylenie
standardowe)
Group I n = 45
(Grupa I)
129.66
1118.83
416.33
228.21
Group II n = 6
(Grupa II)
53.41
583.41
201.75
190.05
Discussion
Interleukin 15 is a glycoprotein secreted mainly by macrophages and monocytes. In terms of
its molecular structure and biological properties,
IL-15 is similar to IL-2 [11–13]. IL-15 participates
in the cell-mediated immune response. It also plays
a significant role beyond the immune system: It
stimulates the process of angiogenesis and is also
a strong inhibitor of apoptosis [14, 15]. It is found
in the amniotic fluid starting from the second trimester of pregnancy. The presence of IL-15 and
the mRNA of IL-15 has been demonstrated in fetal
membranes – the amnion, chorion and decidua, as
well as in the placenta [16, 17].
The main sources of interleukin 18 are macrophages and the epithelial cells, keratinocytes and
osteoblasts [18–20]. IL-18 induces both the cellmediated immune response and the humoral immune response [21, 22]. IL-18’s receptor (IL-18R)
is found in the cells of the syncytiotrophoblast,
interstitial villi and fetal blood cells. The presence of IL-18R in the decidua has been observed
as early as the 6th to 10th week of gestation [23].
IL-18 is present in the amniotic fluid and in the fetal membranes, and increases in its expression are
connected with intrauterine infections, premature
ruptures of fetal membranes and/or risk of premature delivery [24–26].
p
0.032
In the available literature, IL-15 and IL-18
levels in the amniotic fluid have been analyzed
mainly in relation to their participation in the development of intrauterine infections, risk of premature delivery and premature ruptures of fetal
membranes [17, 24–26]. The authors have not
found any research presenting an analysis of the
relationship between the levels of IL-15 and IL-18
in the amniotic fluid and the results of cytogenetic
screening in the fetus.
In fetuses with trisomy 21, various authors
have investigated the concentrations of inhibin
A, inhibin B, inhibin pro-alpha C, activin and follistatin, as well as IL-2 and Transforming Growth
Factor beta (TGF beta) [27–30]. In gestations
complicated by trisomy 21, significantly lower levels of inhibin A, inhibin C and activin in the amniotic fluid have been observed (in the 14th through
19th weeks of gestation) [27, 28]; active IL-2 has
not been found, only a soluble form of its receptor IL-2R [29, 30]. However, the concentration of
a bioactive form of TGF beta in the amniotic fluid
has been found to be significantly higher in fetuses
with an abnormal karyotype [30].
The statistical analysis of the results that the
current authors obtained showed that there is a relationship between abnormal results in cytogenetic screening of the fetus and the concentration of
IL-18 in the amniotic fluid in the second trimester:
204
D. Klimkiewicz-Blok et al.
The average concentration of IL-18 was significantly higher in the fetuses with normal karyotypes in
comparison with the fetuses with abnormal karyotypes. On the other hand, the difference between
the average IL-15 levels in the two groups did not
reach the boundary of statistical significance.
Because the levels of IL-15 i IL-18 in the amniotic fluid in the fetuses with chromosome abnormalities were measured only once, this study
does not provide enough information about the
development of some defense mechanisms. As
noted above, the available literature offers no re-
search about concentrations of IL-15 and Il-18 in
the amniotic fluid in fetuses with abnormal karyotypes. In the authors’ opinion, the results obtained
in this study strongly indicate the potential importance of further research on IL-15 and IL-18
concentrations in the amniotic fluid in the fetuses
with chromosome abnormalities.
The authors concluded that some defense
mechanisms in the second trimester of gestation
in fetuses with chromosome abnormalities may
develop in a different way than in fetuses with normal karyotypes.
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Address for correspondence:
Dominika Klimkiewicz-Blok
Second Department of Gynecology, Obstetrics and Neonatology
Wroclaw Medical University
Borowska 213
50-528 Wrocław
Poland
Tel.: +48 71 733 14 00, +48 600 010 055
E-mail: [email protected]
Conflict of interest: None declared
Received: 31.03.2011
Revised: 13.11.2011
Accepted: 29.03.2012