Biological Research
Namuleme et al. Biological Research
(2025) 58:61
https://doi.org/10.1186/s40659-025-00639-w
Open Access
RESEARCH ARTICLE
IL10 (-1082 G>A, rs1800896) gene
polymorphisms are associated with oxidative
stress in sickle cell disease patients in Uganda
Cissy B. Namuleme1,2, Charles D. Kato1 and Dennis M. Kasozi2*
Abstract
Background Sickle cell disease (SCD) is characterised by chronic oxidative stress. However, there is limited
information on how polymorphisms in cytokine genes influence oxidative stress in SCD patients. The study aimed to
determine the effect of Interleukin gene (IL-10) and Tumor Necrosis Factor (TNFαβ) polymorphisms on oxidative stress
and cytokine levels in SCD patients from Mulago hospital.
Methods A case control study with cross-sectional sample size of 163 SCD patients and 189 healthy controls was
carried out. The extent of oxidative stress was quantified using Malondialdehyde (MDA) by spectrophotometry.
Levels of IL-10 and TNF-α were measured using the Enzyme-Linked Immuno-Sorbent Assay (ELISA). The Amplification
Refractory Mutation System polymerase chain reaction (ARMS-PCR) assay was used to genotype IL10-1082 A > G,
(rs1800896), IL10-819 C > T (rs1800871) and TNF-α-308G > A (rs1800629) and TNF-β + 252 A > G (rs909253) gene
polymorphisms.
Results Samples showed significantly (P = 0.0063) higher median plasma levels of MDA in SCD patients (2.756µM)
than healthy controls (2.364µM). A similar trend was observed with significantly (P < 0.0001) higher median plasma
levels of IL-10 in SCD patients (20.37pg/ml) than healthy controls (7.5pg/ml). The most frequent genotype for IL-10
(-1082, rs1800896) gene polymorphism was heterozygous GA (62.6%). No significant association between IL10
(-1082G > A, rs1800896) gene polymorphisms and SCD was observed (OR = 1.08, 95% CI = 0.54–2.14, P = 0.87). Yet,
IL10 homozygous GG (-1082, rs1800896) (22.12pg/ml) that was found to be significantly associated (P = 0.0234) with
increased plasma levels of IL-10 as compared to heterozygous genotype (GA) (13.94pg/ml) in SCD patients. Similarly,
higher levels of MDA were found to be significantly (P < 0.0001) associated with homozygous GG at IL-10 (-1082,
rs1800896). The most frequent and only reported genotype for TNF-α/β gene polymorphisms were heterozygous GA,
thus no associations were described.
Conclusion In conclusion, our results suggest that the IL10 (-1082 G > A, rs1800896) gene polymorphism is
associated with increased oxidative stress and IL-10 cytokine level in Ugandan SCD patients.
Keywords Sickle cell disease, Oxidative stress, Interleukin 10 gene polymorphisms, TNFαβ gene polymorphisms
*Correspondence:
Dennis M. Kasozi
dmkkasozi@gmail.com; dennis.kasozi@mak.ac.ug
1
Department of Biotechnical and Laboratory Sciences, School of
Biosecurity, College of Veterinary Medicine, Animal Resources and
Biosecurity, Makerere University, P.O. Box 7062, Kampala, Uganda
2
Department of Biochemistry and Systems Biology, School of Biosciences,
College of Natural Sciences, Makerere University, P.O. Box 7062, Kampala,
Uganda
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Namuleme et al. Biological Research
(2025) 58:61
Introduction
Sickle cell disease (SCD) is a neglected major cause of
infant mortality in Africa [1, 2]. Sub-Saharan Africa has
a reported 75% of the global SCD incidence with a predicted increase by 2050 [3]. Uganda has a 13·2% prevalence for sickle cell trait and 0·8% for SCD in children
[4]. SCD is characterised by intravascular haemolysis
and vaso-occlusion events, the key promoters of chronic
inflammation and redox instability [5, 6]. Consequently,
causing gradual small and large vessel vasculopathy,
reperfusion injury and end-organ damage [7]. Malondialdehyde (MDA), a known stable biomarker for oxidative stress has been reported to be high in steady-state
and increased in severe SCD [8]. However, low plasma
levels of IL-10, an anti-inflammatory cytokine have
been reported during crisis and high in steady state SCD
patients [9]. Decreased levels of IL-10 have also been
associated with osteomyelitis in patients [9] suggesting
a protective role of IL-10. An increased production in
IL-10 levels has been associated with GCC alleles unlike
the mutants ATA for − 1082/-819/-592 IL-10 haplotypes
in severe malaria patients [10]. The heterogeneity in the
inflammatory profile of SCD may also be due to differences in populations in addition to genetics [11]. The
study aimed to determine the effect of IL-10 (-1082G > A,
rs1800896) and (-819 C > T, rs1800871), and TNF-α308G > A (rs1800629), TNF-β + 252 A > G (rs909253)
polymorphisms on oxidative stress and IL10 levels in
Ugandan SCD patients from Mulago hospital.
Materials and methods
Study population
This study was approved by Makerere University School
of Health Sciences Research and Ethics Committee
(MAKSHSREC- 2021-90) and a waiver of informed consent to use study participants’ samples was obtained. A
sample size of 150 in each group with a 90% power to
detect a difference between MDA means of 0.57 [8] with
a significance level (alpha) of 0.05 (two-tailed) was determined using GraphPad StatMate 2.00 statistical software.
A total of 352 participants were sampled in this study and
among them were, 163 SCD patients from Mulago hospital sickle cell clinic and 189 healthy controls from Nakasero Blood bank, Central Uganda. Using the sickle cell
anaemia genotyping test [12] SCD patients as cases and
healthy controls were identified. Healthy controls that are
heterozygous with a sickle cell trait were excluded from
the study.
Determination of malondialdehyde, IL-10 and TNFα
concentrations
Whole blood (~ 5mL) was centrifuged at 1000×g for
10 min to obtain 1000 µl of plasma and 500 µl of buffy
coat. The plasma obtained was analysed for MDA
Page 2 of 9
levels to determine the extent of oxidative stress in SCD
patients and controls using methods as described [13].
Plasma levels of IL-10 and TNFα were quantified in both
SCD patients and healthy controls using Enzyme Linked
Immunosorbent Assay (ELISA) kit (BD Biosciences,
Pharmingen, San Diego, USA), following the manufacturer’s instructions.
Genotyping for sickle cell anaemia, IL-10 and TNF αβ gene
polymorphisms
DNA was obtained from the buffy coat layer using methods described by Iranpur-Mobarakeh et al. [14]. Sickle
Cell Anemia genotyping was carried out as described
[12]. Cytokine gene polymorphisms were determined by
Amplification Refractory Mutation System-PCR (ARMSPCR) as described [15]. The ARMS-PCR technique was
for genotyping cytokine gene polymorphisms: IL101082 A > G, (rs1800896), IL10-819 C > T (rs1800871)
and TNF-α-308G > A (rs1800629), TNF-β + 252 A > G
(rs909253) gene polymorphisms. The primer sequences
are in Table 1. A2% agarose gel electrophoresis containing 0.5 mg/ml of ethidium bromide was used to view
the amplified products, against a 50-bp ladder (Thermo
Fisher Scientific, Waltham, MA, USA).
Statistical analysis
Deviation from normality was tested using the
D’Agostino-Pearson omnibus normality test. Age was
expressed as mean ± SD for each study group. Using the
Mann-Whitney test, comparison of MDA levels between
groups and sex for SCD was achieved. The Kruskal-Wallis test was used to compare median MDA levels across
different age groups in SCD. The study groups were
tested for Hardy-Weinberg equilibrium by comparing
the expected with the observed genotype frequencies.
The Chi-square (χ2) test was used to compare gene frequencies between SCD and the Healthy group. Association between genotypes with MDA and IL-10 levels was
achieved using the Mann-Whitney test. All analyses were
calculated with Graph Pad Prism 5.0 Software (Graph
Pad Software, La Jolla, CA, USA). The level of statistical
significance was set as P < 0.05.
Results
Baseline characteristics of the study population
Of the 163 SCD patients, 66 (40.5%) were females. Of
the 189 healthy individuals, 45 (23.8%) were females.
The average age for the SCD group was 9.8 ± 0.64 years,
while that of the control group was 27 ± 0.67 years. SCD
was more prevalent in patients under 5 years (45, 27.6%)
and children aged 5–14 years (82, 50.3%) as compared
to older patients aged above 15 years (36, 22.1%). This
study used a cross-sectional sample size, so the patient
and control groups were not age/sex matched. After
Namuleme et al. Biological Research
(2025) 58:61
Page 3 of 9
Table 1 Primer sequences
Primer name
Wild type β-globin gene
Mutant
β-globin gene
IL-10
(-1082)
IL-10
(-819)
TNF-α-308
TNF-β
(Intron1 + 252)
Internal control HGH
Primer sequence
AS : 5’-ATG GTG CAC CTG ACT CCT GA-3
CP517: 5’CCC CTT CCT ATG ACA TGA ACT-3
AS: 5’-CAG TAA CGG CAG ACT TCT CCA-3’
CP267 (5’-GGG TTT GAA GTC CAA CTC CTA-3’
Generic primer (antisense): 5’-CAGTGCCAACTGAGAATTTGG-3’
Primer G (sense): 5’CTACTAAGGCTTCTTTGGGAG-3’
Primer A (sense): 5’ACTACTAAGGCTTCTTTGGGAA-3’
Generic primer (antisense): 5’-AGGATGTGTTCCAGGCTCCT-3’
Primer C (sense): 5’-CCCTTGTACAGGTGATGTAAC-3’
Primer T (sense): 5’-ACCCTTGTACAGGTGATGTAAT-3’
Generic primer (antisense): 5’-TCTCGGTTTCTTCTCCATCG-3’
Primer G (sense):5’-ATAGGTTTTGAGGGGCATGG-3’ (TNF1 allele)
Primer A (sense): AATAGGTTTTGAGGGGCATGA-3’ (TNF2 allele
Generic primer (antisense): 5’-AGATCGACAGAGAAGGGGACA-3’
Primer G (sense): 5’-CATTCTCTGTTTCTGCCATGG-3’
Primer A (sense): 5’-CATTCTCTGTTTCTGCCATGA-3’
Forward primer: 5’-GCCTTCCCAACCATTCCCTTA-3’
Reverse primer: 5’-TCACGGATTTCTGTTGTGTTTC-3’
Product size
517 bp
267 bp
258 bp
233 bp
154 bp
94 bp
429 bp
IL10: Interleukin 10, TNFαβ: tumor necrosis factor, HGH: human growth hormone
genotyping (Fig. 1A), a total of 9 (4.7%) individuals were
identified as carriers for the sickle cell gene and excluded
from the healthy control group.
Levels of oxidative stress and IL-10 differed significantly
between SCD patients and healthy controls
Oxidative stress was determined through the plasma
analysis of MDA levels in SCD patients (N = 163) and
controls (N = 189). The D’Agostino-Pearson test results
for MDA (K2 = 9.483, p = 0.0087) and IL-10 (K2 = 78.82,
p < 0.0001) indicated that the data for both analytes
are not normally distributed. Results showed that
median plasma levels of MDA were significantly higher
(P = 0.0002, Mann-Whitney test, Fig. 1B) in SCD patients
(2.756µM) as compared to healthy controls (2.364µM).
The role of cytokines in the modulation of SCD was demonstrated through the assay of IL-10 cytokines in the
plasma of both SCD patients (N = 163) and healthy controls (N = 189). The detection limits for the assays were
14.2pg/ml (IL-10). Median plasma levels for IL-10 were
significantly higher (P < 0.0001, Fig. 1C, Mann-Whitney
test) in the plasma of SCD patients (20.37pg/ml) as compared to healthy controls (7.5pg/ml). On the other hand,
plasma levels of TNF-α were not significantly different
between SCD patients and healthy controls (Fig. 1D).
Prevalence of IL-10, TNF-α and TNF-β genes
polymorphisms in SCD patients and healthy controls
The genotypes for IL-10 (-1082 > G/A, rs1800896) polymorphism were deduced from the presence or absence
of a 258 bp amplicon specific for either G or A and
both alleles (Fig. 2A). A 429 bp amplicon of the HGH
as internal control was also observed in the gel, indicating optimal amplification of sample DNA of the study
participants.
Our study shows that heterozygous GA was the most
common genotype for IL-10 (-1082 G > A, rs1800896)
polymorphism in both patients (62.61%) and healthy
controls (64.3%). Similarly, 35.65% of SCD patients had
a homozygous GG genotype while the control group
scored 33.9%. The least genotype observed for IL-10
(-1082 G > A, rs1800896) was homozygous AA, with
1.74% in patients and 1.8% in healthy controls (Table 2).
However, statistical analysis did not yield any significant
(P < 0.05, Chi-square test) difference when IL-10 (-1082
G > A, rs1800896) genotype frequency was compared in
patients and healthy controls. There was also no significant association between IL-10 (-1082 G > A, rs1800896)
genotypes, GG (OR = 1.08, 95% CI = 0.54–2.14, P = 0.87);
GA (OR = 0.93, 95%CI = 0.48–1.82, P = 0.87); AA
(OR = 0.97, 95%CI = 0.11–14.34, P > 0.9999, Fisher’s exact
test) and SCD. The G allele for IL-10 (-1082 G > A) polymorphism was more frequent in the study population as
compared to the A allele.
For IL-10 (-819 C > T, rs1800871) polymorphism, genotypes were deduced from the presence or absence of
a 233 bp amplicon specific for either C or T and both
alleles (Fig. 2B). The most frequent genotype for IL-10
(-819 C > T, rs1800871) polymorphism in both SCD
patients (99.13%) and healthy controls (100%) was heterozygous CT. The TT genotype was absent in the study
population, while the CC genotype was present in the
patient’s group (0.87%) but not in the healthy control
group (0%) (Table 2). The genotypes for IL-10 (-819 C > T,
Namuleme et al. Biological Research
(2025) 58:61
Page 4 of 9
Fig. 1 Levels of MDA, IL10 and TNFα between SCD patients and healthy control groups. (A) A representative gel showing results of sickle cell anaemia
genotyping. Lane 1; DNA ladder, lanes 2 & 3; HbAS bands, lanes 4 & 5; HbSS bands, lanes 6 & 7; HbAA bands, (B) MDA (C) IL10 and TNF (D) levels differed
between sickle cell disease and healthy controls. MDA: Malondialdehyde, IL10: Interleukin − 10, SCD: Sickle cell disease. HbSS: sickle cell anemia, HbAA:
normal Hemoglobin, HbAS: heterozygous sickle cell individuals (carriers). “*” indicates a difference between SCD patients and healthy control groups. *P
< 0.05, **P < 0.01,***P < 0.001, **** P < 0.0001. Data analysis by Mann-Whitney test. Outliers not shown
rs1800871) polymorphism did not yield any significant
(P > 0.9999, Fisher’s exact test) association with SCD. The
allele frequency for IL-10 (-819 C > T) polymorphism
was comparable between C and T alleles in the study
population.
The genotypes for TNF-α (308 > G/A, rs1800629)
and TNF-β (Intron1 + 252 > G/A, rs909253) polymorphisms were deduced from the presence or absence of
a 154–94 bp amplicon specific for either G or A, and
both alleles, Fig. 2C and D, respectively. Results from
our study showed heterozygous GA (100%) as the most
frequent and only genotype present in our study population for both TNF-α (308 > G/A, rs1800629) and TNF-β
(Intron1 + 252 > G/A, rs909253) polymorphisms.
Association between IL10 genotypes with plasma levels of
malondialdehyde and IL-10
Comparisons between IL-10 (-1082 GG vs. GA,
rs1800896) genotypes with plasma levels of MDA yielded
a significant difference (Mann-Whitney test, P < 0.0001)
in SCD patients (Fig. 3A). Higher median levels of MDA
were observed in patients with GG (3.35µM) genotype
as compared to those with GA (2.30µM) genotypes. To
determine whether IL-10 (-1082 G > A, rs1800896) gene
polymorphism was associated with changes in IL-10
levels, plasma concentrations of IL-10 were compared
across IL-10 (GG vs. GA) genotypes in SCD patients.
There was a significant difference (Mann-Whitney test,
P = 0.0234, Fig. 3B) in IL-10 levels across the genotypic
groups. Homozygous GG (22.12pg/ml) genotype showed
higher median plasma levels of IL-10 as compared to GA
(13.94pg/ml) genotypes. Comparisons were not made
for other cytokine gene polymorphisms, including IL-10
Namuleme et al. Biological Research
(2025) 58:61
Page 5 of 9
Fig. 2 ARMS-PCR of IL-10 and TNFα/β genotypes. Agarose gel electrophoresis of the ARMS PCR assay products. The 429 bp amplification product of the
HGH control was present in all lanes, showing optimal amplification. M = 50 bp ladder, NC = Negative control. (A) IL-10 (-1082 > G/A): Lane 1G- 1 A = Homozygous GG; Lanes 2G- 2 A and 3G- 3 A = Homozygous AA and Lane 4G- 4 A = Heterozygous GA for IL-10 (-1082 G > A) polymorphism. (B) IL-10
(-819 C > T): Lane 1 C- 1T = Homozygous CC; and Lanes 2 C- 2T, 3 C- 3T and 4 C- 4T = Heterozygous CT for IL-10 (-819 C > T) polymorphism. (C) TNF-α
(308 > G/A) genotypes from ARMS-PCR amplification. From left to right: NC = Negative control; Lanes 1G- 2 A; 3G- 4 A and 5G- 6 A = Heterozygous GA for
TNF-α (308 > G/A) polymorphism in sickle cell disease patients. (D) TNF-β (Intron1 + 252 > G/A) genotypes from ARMS-PCR amplification. From left to right:
NC = Negative control; Lanes 1G- 2 A; 3G- 4 A and 5G- 6 A = Heterozygous GA for TNF-β (Intron1 + 252 > G/A) polymorphism in sickle cell disease patients
Table 2 Genotypic and allelic frequency distribution of IL-10 polymorphisms
Cytokine gene
Polymorphism
IL-10 (-1082G > A)
GG
GA
AA
IL-10 (-819 C > T)
CC
CT
TT
Sickle cell patients
Genotypic frequency
N (%)
Allelic frequency
Healthy controls
Genotypic frequency
N (%)
Allelic frequency
Statistical analysis
P-value (OR, 95% CI)
41 (35.65)
72 (62.61)
02 (1.74)
G = 0.6696
A = 0.3304
19 (33.9)
36 (64.3)
01 (1.8)
G = 0.6607
A = 0.3393
0.87 (1.08, 0.54–2.14)
0.87 (0.93, 0.48–1.82)
> 0.99 (0.97, 0.11–14.34)
01 (0.87)
114 (99.13)
00 (0)
C = 0.504
T = 0.496
00 (0)
56 (100)
00 (0)
C = 0.5
T = 0.5
> 0.99
> 0.99 (0.00, 0.00- 18.48)
OR = odds ratio; CI = confidence interval
(819 > C/T, rs1800871), TNF-α (308 > G/A, rs1800629),
and TNF-β (Intron1 + 252 > G/A, rs909253), because
their genotypes lacked the required heterogeneity in the
sampled population.
Discussion
Oxidative stress and inflammation contribute significantly to the pathophysiology of SCD [16]. Our study
found that the IL10 (-1082G > A, rs1800896) gene polymorphism is associated with increased levels of IL10
and oxidative stress in SCD patients in Uganda. The key
sources of oxidant injury in SCD include increased levels of cell-free hemoglobin following chronic hemolysis,
mechanisms leading to vaso-occlusion ischemia-reperfusion and inflammation [7]. Similarly, activation of inflammatory cells and their signalling pathways culminates
into the release of molecules that drive the inflammatory
state in SCD such as cytokines, chemokines and growth
factors [7]. TNFα is a pro-inflammatory cytokine and is
generated as an early consequence of ischemia reperfusion [17] with increased levels being detected during pain
crisis. While IL-10 cytokine is known to limit the production of pro-inflammatory cytokines such as TNF-α, it
is also found to be elevated in steady-state SCD patients
[18]. Recently, polymorphisms in cytokine genes have
also been associated with increased cytokine production
Namuleme et al. Biological Research
(2025) 58:61
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Fig. 3 MDA and IL10 levels Between IL-10 genotypes. (A) MDA and IL10 (B) levels differed between GG, GA and AA in patients with SCD. MDA: Malondialdehyde, IL10: Interleukin − 10, SCD: Sickle cell disease. “*” indicates a difference between SCD patients and healthy control groups. *P < 0.05, **P < 0.01,***P
< 0.001, **** P < 0.0001. Data analysis by Mann-Whitney test. Outliers not shown
and consequently, a heterogeneous clinical outcome of
SCD in patients with stroke, leg ulcers, splenic sequestration and end-organ damage among others [19]. Our current research aimed at studying the relationship between
SCD pathogenesis and the key modifiers of disease severity like oxidative stress, cytokine levels and cytokine gene
polymorphisms in the Ugandan population.
The median plasma levels of MDA were significantly
higher in SCD patients as compared to healthy controls.
These results were consistent with previous studies,
reporting increased levels of MDA in severe SCD (with
pain crises) and steady state patients (without pain crises) as compared to healthy controls [20, 21]. However,
contradicting results for MDA levels in SCD when compared to healthy controls have also been reported [22].
The extent of oxidative damage measured as MDA in
patients was higher due doubled generation of reactive
oxygen species during intracellular catabolism and from
the pathological events of a sickled red blood cell such as
increased hemoglobin autoxidation [23] increased release
of cell free hemoglobin [24] and pro-inflammatory molecules [5]. Likewise, our comparison of median MDA levels across sex and different age groups in SCD patients
did not yield any significant difference, attributing to SCD
pathogenesis was the primary source of increased oxidative damage [25]. Oxidative damage in patients usually
results into endothelial dysfunction, vaso-occlusive pain,
early organ damage and continuous inflammation [16].
This study also found significantly higher plasma levels of
IL-10 in SCD patients as compared to healthy controls.
This finding agreed with previous results that showed
increased serum levels of IL-10 in steady-state SCD and
its possible inhibition of both humoral and cell-mediated
immune functions [18, 23]. The SCD patients included
in this current study were asymptomatic cases. Contrary
to our results, no significant difference in serum levels of IL-10 between SCD patients and healthy controls
was reported in Brazil [26]. Nonetheless, being an antiinflammatory molecule, IL-10 inhibits the synthesis of
TH1cytokines, such as TNF-α, IL-1, IL-6, and IL-8. The
plasma levels of TNF-α were not significantly different
between SCD patients and healthy controls [27].
The production of IL-10 can be controlled at the transcriptional level consequently, the 3 bi-allelic singlenucleotide polymorphisms from the transcription start
site, at positions − 1082 G > A, -819 C > T and − 592 C > A
have been studied [28]. The genotype frequency differences reported for IL-10 (-1082G > A, rs1800896) in this
study were not statistically significant despite similar
group sizes between SCD patients and healthy controls.
This finding was in agreement with previous studies [26].
However, our sample population showed heterozygous
GA as the most frequent genotype for IL-10 (-1082G > A,
rs1800896) polymorphism followed by GG. Our results
were similar to those for IL-10 (-1082G > A, rs1800896)
genotype frequency reported from India [18] and Brazil [19] in SCD patients. However, a different trend of
AA as the most frequent genotype, followed by GA and
GG has been reported for (-1082G > A, rs1800896) polymorphism in Kenya [10] and in Brazil [29] respectively
which could be due to differences in the population
structure. The genotype and allele frequencies of the IL10
(-1082G > A, rs1800896) and IL10 (-819 C > T, rs1800871)
corroborate with those reported from seven African subpopulations including the African Caribbean in Barbados
(ACB), African ancestry in Southwest US (ASW), Esan
Namuleme et al. Biological Research
(2025) 58:61
in Nigeria (ESN), Gambian in Western Division (GWD),
Gambia, Luhya in Webuye, Kenya (LWK), Mende in
Sierra Leone (MSL) and the Yoruba in Ibadan, Nigeria
(YRI) in the 1000 genomes project. The source of variation in findings may be attributed to population heterogeneity and sampling methods used. Similarly, the IL-10
(-819 C > T, rs1800871) genotypic frequency showed
no significant difference when compared between SCD
patients and healthy controls. This finding was agreement with previous studies [10, 19, 26]. We did not investigate IL-10 -592 position because it was reported to be
in LD with the − 819 position. The alleles for − 819 C > T
and − 592 A > C are inherited together [28] thus, in our
current study, the IL-10 (-819 C > T, rs1800871) SNPs was
characterized. The most frequent genotype in our SCD
study population was heterozygous CT. The mutant genotype TT was absent in the sampled SCD population. A
similar trend for IL-10 (-819 C > T, rs1800871) genotype
frequency was reported [10, 19] but a variation in results
is due to population structure and sampling methods
used.
Plasma changes in IL-10 levels were significantly different across the IL-10 (-1082G > A, rs1800896) gene
polymorphism with homozygous GG genotype showing
higher median levels of IL-10 as compared to GA + AA
genotypes in SCD patients. Consistent with this current study, individuals positive for the mutant allele A at
position − 1082 for IL-10 had significantly higher IL-10
production as compared to those negative for the A
allele [30, 31]. This association was independent of the
(-819 C > T, rs1800871) polymorphisms. Alternatively,
other studies [10] also reported that the GCC haplotype
was associated with increased IL-10 production unlike
the ATA haplotype in patients with severe malaria [32].
Enhanced binding of transcriptional factors that promote
higher IL-10 production maybe favoured by the presence of GCC haplotype unlike the ATA haplotype that
may prime enhanced binding sites for repressors and
thus reduced IL-10 production [10]. As anti-inflammatory molecule, IL-10 inhibits the production of type-1
cytokine that drive the inflammatory state in SCD, and
changes in the cytokine can be used in vaso-occlusion
crisis prognosis [23].
Similarly, plasma levels of MDA were found to be significantly different across IL-10 genotypes with homozygous GG genotype showing higher levels of MDA as
compared to GA + AA genotypes for IL-10 (-1082 G > A,
rs1800896) gene polymorphism in SCD patients. However, molecular mechanisms linking IL-10 genotype to
oxidative stress remain unclear. A wide range of transcription factors and receptors, like the nuclear factor-κB
(NF-κB) and activator protein-1 (AP-1) [33], which
regulate the expression of many genes, including those
involved in the production of both pro-inflammatory
Page 7 of 9
and anti-inflammatory cytokines [34]. However, little
research has been done on the possible inter-relationship
between oxidative stress and inflammation in SCD.
This study had some limitations. First, samples were
not representative of the entire population since they
were obtained from the Mulago hospital located in the
central region whereas Uganda is an ethnically diverse
country. Secondly, samples were not age/sex matched
and multivariate analyses could not be performed.
Thirdly, besides IL-10 (-1082G > A, rs1800896), IL-10
(-819 C > T, rs1800871), several other SNPs in other cytokines may affect the relation between cytokine levels and
oxidative stress in SCD patients. However, this is the
first study in Uganda that provides useful insights into
the association between cytokine gene polymorphisms,
cytokine levels and oxidative stress in SCD patients. In
further research, a multi-site study with diverse ethnic
participants may be necessary to investigate the association between SNPs, cytokine levels and oxidative stress in
Ugandan SCD patients.
Conclusion
Collectively, results from this study suggest that SCD is
associated with increased IL-10 cytokine and plasma
levels of oxidative stress. Also, IL-10 (-1082 > G/A,
rs1800896) gene polymorphism was associated with
changes in IL-10 levels but the genotype frequency differences were not statistically significant despite similar
group sizes between SCD patients and healthy controls.
Abbreviations
ARMSPCR Amplification Refractory Mutation System PCR
ELISAEnzyme Linked Immunosorbent Assay
EDCTP2European and Developing Countries Clinical Trials
Partnership
HbAAHomozygous normal hemoglobin
HbASHeterozygous sickle hemoglobin
HbSSHomozygous sickle cell recessive hemoglobin
HGHHuman growth hormone
IL-10Interleukin- 10
MDAMalondialdehyde
MAKSHSRECMakerere University School of Health Sciences Research and
Ethics Committee
MAPRONANOMaterials, Product Development and Nanotechnology
ROSReactive Oxygen Species
SIDASwedish International Development Cooperation Agency
SCDSickle Cell disease
SCASickle Cell Anemia
SNPsSingle nucleotide polymorphisms
TNF-αTumor Necrosis Factor Alpha
TNF-βTumor Necrosis Factor beta
Acknowledgements
The authors are grateful to the staff of the Molecular Biology Laboratory the
College of Veterinary Medicine, Animal Resources and Biosecurity and the
Laboratory of Molecular Biology at the Department of Biochemistry and
Systems Biology, College of Natural Sciences at Makerere University for their
support with sample analysis.
Author contributions
CBN, CDK and DMK performed the following: Conceptualization,
Methodology, validation, formal analysis, investigation, data curation, writing
Namuleme et al. Biological Research
(2025) 58:61
– original draft, Writing - Review & Editing. CBN conducted the Laboratory
analysis of the study in partial fulfilment of the requirements for the award of
the degree of Master of Science in Molecular Biology and Biotechnology of
Makerere University. CDK and DMK supervised CBN during the conduct of the
study.
Funding
This study was funded in part by the Swedish International Development
Cooperation Agency (Sida) and Makerere University under Sida Contribution
No: 51180060. The grant is part of the European and Developing Countries
Clinical Trials Partnership (EDCTP2) programme supported by the European
Union. This was a Postdoctoral award to DMK from DRGT 377 Project of
Makerere University – Sweden bilateral Research programme (2015–2020).
CBN received a partial Master’s scholarship from the Africa Center of
Excellence in Materials, Product Development and Nanotechnology
(MAPRONANO ACE), CEDAT-Makerere University. The funding bodies did not
have any involvement in the design of this study or in the collection, analysis,
and interpretation of data or in writing of the manuscript. All authors read and
approved the final manuscript.
Data availability
All data generated or analysed during this study are included in this published
article. The UniProt accession numbers for IL-10, TNF-α and TNF-β were
P22301, P01375 and P01374 respectively.
Page 8 of 9
9.
10.
11.
12.
13.
14.
15.
16.
17.
Declarations
Ethics approval and consent to participate
This study was approved by the Makerere University School of Health Sciences
Research and Ethics Committee (MAKSHSREC-2021-90). A waiver of informed
consent to use both the SCD blood samples from mother study, and healthy
control blood samples from Blood bank, Nakasero was obtained.
18.
19.
Consent for publication
All authors reviewed and approved the manuscript for Publication.
20.
Competing interests
The authors declare that they have no competing interests.
21.
Received: 23 April 2025 / Accepted: 25 August 2025
22.
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