THE EFFECT OF MICRO-RNA 466i ON VASO-OCCLUSIVE COMPLICATIONS OF SICKLE CELL ANAEMIA

Abstract

BACKGROUND INFORMATION

Sickle cell anaemia is an inherited autosomal disease that is very common
among people of African, Asian, South European and Middle Eastern descent.
The prevalence of sickle cell anaemia in Nigeria is between 1-3%. Vaso
occlusion in sickle cell anaemia is mediated via increased expression of adhesion
molecules and is thought to be associated with recurrent or continuous
inflammation. Recurrent vaso-occlusion can lead to widespread hypoxia,
ischaemia and tissue or organ dysfunction. Micro-RNA 466i up-regulates the
expression of interleukin-10(an anti-inflammatory cytokine), by antagonizing
the RNA binding protein tristetraprolin, which mediates interleukin-10
messenger RNA degradation.
STUDY SETTING
This was a cross-sectional study of 50 sickle cell anaemia patients recruited from
the out-patient department of University of Nigeria Teaching Hospital, Ituku
Ozalla, Enugu, South-East Nigeria, between November 2013 and October 2014.
They were selected by simple consecutive sampling and categorized into two
groups. Group A were patients that had one or more vaso-occlusive
complications and group B were those that had no vaso-occlusive complication
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at the time this study was done. The study was designed to find out if there is a
relationship between the quantity of micro-RNA 466i and the number of vaso
occlusive complications of sickle cell anaemia. I also wanted to investigate for
any relationship between the levels of interleukin-10 and the occurrence of these
complications.
OUTCOME MEASURES.
The dependent variables assessed were the presence and absence of vaso
occlusive complications. The independent variables measured were micro-RNA
466i and interleukin-10, total white blood cell count and differentials, platelet
count and haemoglobin.
METHODOLOGY
Red blood cells were lysed using ammonium chloride. The resulting white blood
cell pellets were lysed in guanidium isothiocyanate (GITC) lyses buffer. From
the GITC lysate, total RNA was extracted. Thereafter, the amount of micro
RNA 466i was quantified. Interleukin-10 was quantified in plasma by Enzyme
Linked Immunosorbent Assay (ELISA). The Full Blood Count was done using
the mythic 22 automated blood cell counter.
RESULTS
The mean levels of normalized micro-RNA 466i in group A was 99.9±15.9 and
78.1±17.5 in group B. Twenty patients , each with one complication had a mean
microRNA 466i of 7529 ± 563 copies/5µl of cDNA and mean IL-10 levels of
12.88 ± 3.135 pg/ml while five patients, each with two complications had a
mean micro-RNA 466i of 5375 ± 1458 copies/5µl of cDNA and mean IL-10
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level of 8.44 ± 1.24pg/ml. Those patients ≤ 25 years had a mean micro-RNA
466i of 5458 ± 531 copies/5µl of cDNA, while those > 25 to ≤ 50 years had a
mean micro-RNA 466i 0f 7231 ± 595 copies/5µl of cDNA. Male patients had a
mean micro-RNA 466i of 7735 ± 1186 copies /5µl of cDNA while the female
patients had a mean micro-RNA 466i of 6447 ± 660 copies/5µl of cDNA.
CONCLUSION
The result showed that there was no significant difference in the quantities of
microRNA 466i between patients with and without vaso-occlusive
complications of sickle cell anaemia, p=0.9307. Also, there was no significant
difference in the quantities of micro-RNA 466i among patients who had no, one
or two vaso-occlusive complications, p=0.066. There was no significant
difference in the levels of IL-10 between patients with and without vaso
occlusive complications of sickle cell anaemia, p=0.0809. There was no
significant difference in the levels of IL-10 among patients who had no, one or
two vaso-occlusive complications of sickle cell anaemia, p=0.757
However, there was a significant difference in the absolute neutrophil count
between patients with and without vaso-occlusive complications of sickle cell
anaemia, P=0.008. Finally, the study showed that microRNA 466i increases with
age, p=0.03. There was no significant difference in the mean quantities of micro
RNA 466i between the males and the females patients, p = 0.370.