DNA methyltransferase 3B gene promoter and interleukin-1 receptor antagonist polymorphisms in childhood immune thrombocytopenia

Interleukin-1 Receptor Antagonist Gene Polymorphisms in Egyptian Children and Adolescents With Primary Immune Thrombocytopenia: Association With Disease Susceptibility, Response to Therapy, and Outcome

Immune thrombocytopenia (ITP) is one of the most common hematologic disorders with poorly predictable clinical course and outcome. We studied the distribution of interleukin 1 receptor antagonist (IL-1Ra) gene polymorphism (intron-2) among children and adolescents with ITP and correlated IL-1Ra gene polymorphism to disease susceptibility, response to therapy, and outcome. Sixty children with ITP (mean age: 9.2±4.5 y) and 100 healthy controls (mean age: 8.83±4.05 y) were enrolled. The frequencies of the allele A2 and genotype A1A2 were significantly higher in patients compared with controls ( P <0.0001, P =0.0008, respectively). Allele A2 conferred 3.1 times increased relative risk for disease development. Allele A2 and genotypes A1A2 and A2A2 were significantly more frequent among remitted patients ( P =0.028 and 0.024, respectively). There was no significant difference between different genotypes and alleles regarding bleeding score ( P >0.05). Patients with polymorphic allele A2 (A1A2/A2A2) showed significantly better response to steroids than those with homozygous wild allele A1 ( P =0.028). IL-1Ra polymorphism might contribute to the susceptibility to ITP in Egyptian children. The presence of A2 polymorphic allele of IL-1Ra gene was found to be associated with better disease outcome and response to steroids than those with homozygous wild allele.

The role of epigenetics in childhood autoimmune diseases with hematological manifestations

Autoimmune diseases with hematological manifestations are often characterized by chronicity and relapses despite treatment, and the underlying pathogenetic mechanisms remain unknown. Epigenetic alterations play a vital role in the deregulation of immune tolerance and the development of autoimmune diseases. In recent years, study of epigenetic mechanisms in both adult and childhood autoimmune disorders has been seeking to explain the pathophysiology of these heterogeneous diseases and to elucidate the interaction between genetic and environmental factors. Various mechanisms, including DNA methylation, histone modifications (chromatin remodeling), and noncoding RNAs (ncRNAs), have been studied extensively in the context of autoimmune diseases. This paper summarizes the epigenetic patterns in some of the most common childhood autoimmune disorders with hematological manifestations, based on epigenetic studies in children with primary immune thrombocytopenia (ITP), systemic lupus erythematosus (SLE), and juvenile idiopathic arthritis (JIA). Research findings indicate that methylation changes in genes expressed on T cells, modifications at a variety of histone sites, and alterations in the expression of several ncRNAs are involved in the pathogenesis of these diseases. These mechanisms not only determine the development of these diseases but also affect the severity of the clinical presentation and biochemical markers. Further studies will provide new tools for the prevention and diagnosis of childhood autoimmune disorders, and possible novel treatment options.

Interleukin (IL)-1 family cytokines could differentiate primary immune thrombocytopenia from systemic lupus erythematosus-associated thrombocytopenia

Background

Primary immune thrombocytopenia (ITP) is an autoimmune-mediated disorder characterized by a decreased platelet count. Systemic lupus erythematosus (SLE) is also an autoimmune disease in which thrombocytopenia is a common hematologic manifestation. Interleukin (IL)-1 family cytokines are major proinflammatory and immunoregulatory mediators. This study aimed to investigate the role of IL-1 cytokines in patients with ITP and SLE and the potential pathophysiologic mechanism to differentiate SLE-associated thrombocytopenia (SLE-TP) from ITP.

Methods

Multiplex cytokine assay and real-time polymerase chain reaction (RT-PCR) were used to measure IL-1 cytokines in 17 newly diagnosed ITP patients, 17 SLE-TP patients, 19 SLE patients without thrombocytopenia (SLE-NTP), and 10 healthy controls.

Results

The serum levels of IL-1β, IL-18, IL-36α, IL-36β, IL-36γ, and IL-33 were decreased significantly in ITP patients compared with SLE-TP patients, SLE-NTP patients, and healthy controls (P<0.05). While there was no significant difference in the serum level of IL-37 between ITP and SLE-TP patients, there was a positive correlation between the platelet count and IL-37 level in ITP patients. Our data suggested that serum IL-1β, IL-18, IL-36α, IL-36β, IL-36γ, IL-33, and IL-37 could be considered biomarkers in the diagnosis of ITP.

Conclusions

Serum IL-1β, IL-18, IL-36α, IL-36β, IL-36γ, and IL-33 could be considered biomarkers to differentiate SLE-TP from ITP patients.

The influence of DNMT3A and DNMT3B gene polymorphisms on acute myeloid leukemia risk in a Moroccan population

Acute myeloid leukemia (AML) is a very complex disease that is linked to environmental, genetic and epigenetic factors. Several Studies have found that aberrations in DNA methylation process play a crucial role in leukemogenesis. The aim of this case control study was to evaluate the association between rs1569686, rs2424913 polymorphisms located in DNMT3B gene and rs7590760 polymorphism located in DNMT3A gene and AML risk in a Moroccan population.

MATERIALS AND METHODS

The present study was conducted in 142 cases of AML and 179 control subjects from the Moroccan population. Genomic DNA was isolated from whole blood samples by salting-out method and the genotype of the three polymorphisms was determined by the PCR-RFLP technique.

RESULTS

The study results indicated that rs1569686 polymorphism was significantly associated with the risk of AML in dominant model (OR=1.72, 95 % CI 1.01-2.95, P=0.04), but not in recessive model. In stratified analysis by gender, statistically significant association between the rs2424913 CT genotype and AML was found among males (OR=2.05, 95 % CI 1.00-4.19, P=0.04). Similarly, the rs1569686 TT genotype was associated with an increase risk of AML (OR=3.21, 95 % CI 1.15-8. 98, P=0.02), this association was also found under dominant genetic model (OR=2.47, 95 % CI 1.07-5. 67, P=0.03) among males. However, the rs2424913 polymorphism was not associated with AML.

CONCLUSION

Our findings have shown that rs1569686 polymorphism might be a risk factor of AML in males. While, the rs2424913 polymorphism was not associated with AML. Further studies with a large sample size are needed to validate our results.

DNMT3B rs1569686 and rs2424913 gene polymorphisms are associated with positive family history of preterm birth and smoking status

AIM

To evaluate the association between spontaneous preterm birth (SPTB) and DNA methyltransferase (DNMT)1, 3A, 3B, and 3L gene polymorphisms, and their contribution to the clinical characteristics of women with SPTB and their newborns.

METHODS

This case-control study, conducted in 2018, enrolled 162 women with SPTB and 162 women with term delivery. DNMT1 rs2228611, DNMT3A rs1550117, DNMT3B rs1569686, DNMT3B rs2424913, and DNMT3L rs2070565 single nucleotide polymorphisms were genotyped using polymerase chain reaction and restriction fragment length polymorphism methods. The clinical characteristics included in the analysis were family history of preterm birth, maternal smoking, maternal age, gestational week at delivery, and fetal birth weight.

RESULTS

DNMT gene polymorphisms were not significantly associated with SPTB. DNMT3B rs1569686 and rs2424913 minor alleles (T) were significantly more frequent in women with familial PTB than in women with non-familial PTB, increasing the odds for familial PTB 3.30 and 3.54 times under dominant genetic models. They were also significantly more frequent in women with SPTB who smoked before pregnancy, reaching the most significant association under additive genetic models (odds ratio 6.86, 95% confidence interval 2.25-20.86, P<0.001; odds ratio 3.77, 95% confidence interval 1.36-10.52, P=0.011, respectively).

CONCLUSIONS

DNMT3B rs1569686 and rs2424913 gene polymorphisms might be associated with positive family history of PTB and smoking status.

Association of Polymorphisms in Genes Involved in One-Carbon Metabolism with MTHFR Methylation Levels

Methylenetetrahydrofolate reductase (MTHFR) is a pivotal enzyme in the one-carbon metabolism, a metabolic pathway required for DNA synthesis and methylation reactions. MTHFR hypermethylation, resulting in reduced gene expression, can contribute to several human disorders, but little is still known about the factors that regulate MTHFR methylation levels. We performed the present study to investigate if common polymorphisms in one-carbon metabolism genes contribute to MTHFR methylation levels. MTHFR methylation was assessed in peripheral blood DNA samples from 206 healthy subjects with methylation-sensitive high-resolution melting (MS-HRM); genotyping was performed for MTHFR 677C>T (rs1801133) and 1298A>C (rs1801131), MTRR 66A>G (rs1801394), MTR 2756A>G (rs1805087), SLC19A1 (RFC1) 80G>A (rs1051266), TYMS 28-bp tandem repeats (rs34743033) and 1494 6-bp ins/del (rs34489327), DNMT3A -448A>G (rs1550117), and DNMT3B -149C>T (rs2424913) polymorphisms. We observed a statistically significant effect of the DNMT3B -149C>T polymorphism on mean MTHFR methylation levels, and particularly CT and TT carriers showed increased methylation levels than CC carriers. The present study revealed an association between a functional polymorphism of DNMT3B and MTHFR methylation levels that could be of relevance in those disorders, such as inborn defects, metabolic disorders and cancer, that have been linked to impaired DNA methylation.

Interleukin-1B (IL-1B-31 and IL-1B-511) and interleukin-1 receptor antagonist (IL-1Ra) gene polymorphisms in primary immune thrombocytopenia

Background

Immune thrombocytopenia (ITP) is an immune-mediated disease caused by autoantibodies against platelets membrane glycoproteins GPIIb/IIIa and GPIb/IX. The etiology of ITP remains unclear. This study evaluated the association of polymorphisms in interleukin (IL)-1B-31, IL-1B-511, and IL-1Ra with ITP.

Methods

Genotyping of IL-1B-31, IL-1B-511, and IL-1Ra was performed in 118 ITP patients and 100 controls by polymerase chain reaction restriction fragment length polymorphism and detection of variable number tandem repeats.

Results

Genotype differences in IL-1B-31 and IL-1Ra were significantly associated with ITP. Patients showed a higher frequency of the IL-1B-31 variant allele (T) and a 1.52-fold greater risk of susceptibility to ITP (odds ratio [OR]=1.52, 95% confidence interval [CI]=1.04–2.22, P=0.034). The frequencies of both homozygous and heterozygous variant genotypes of IL-1B-31 were higher (OR=2.33, 95% CI=1.069–5.09, P=0.033 and OR=2.044, 95% CI=1.068–39, P=0.034) among patients and were significantly associated with ITP susceptibility. Both homozygous and heterozygous variant genotypes of IL-1Ra were also more frequent (OR=4.48, 95% CI=1.17–17.05, P=0.0230 and OR=1.80, 95% CI=1.03–3.14, P=0.0494) among patients and were associated with ITP risk. IL-1B-31 and IL-1Ra also showed significant association with severe ITP. However, IL-1B-511 was not associated with ITP.

Conclusion

IL-1B-31 and IL-1Ra polymorphisms may significantly impact ITP risk, and they could be associated with disease severity, which may contribute to the pathogenesis of ITP.

Association of DNA Methyltransferase 3B Promotor Polymorphism With Childhood Chronic Immune Thrombocytopenia

BACKGROUND

DNA methylation is an epigenetic process that refers to chromatin-based mechanisms in the regulation of gene expression without DNA alternation. It is mediated by DNA methyltransferases (DNMTs). The DNA methyltransferase 3B (DNMT3B) gene contains a C-to-T single nucleotide polymorphism (SNP; rs2424913) in the Promotor region, 149 base pairs from the transcription start site, which is reported to significantly increase the Promotor activity.

OBJECTIVE

To investigate the prevalance of rs2424913 single nucleotide polymorphism located in the DNMT3B gene Promotor.

METHODS

In the present study, we investigated the prevalence of rs2424913 single nucleotide polymorphism located in DNMT3B gene Promotor by restriction fragment length polymorphism (PCR-RFLP) in Egyptian pediatric chronic immune thrombocytopenia (ITP) patients and controls.

RESULTS

The homozygous genotype (TT) was significantly higher in our patient and conferred almost 3-fold increased risk of chronic ITP when compared to controls.

CONCLUSION

The present study shows that DNMT3B rs2424913 promotor polymorphism represents a genetic risk factor that may play an important role in understanding the pathogenesis of chronic ITP.

Association of DNA methyltransferase polymorphisms with susceptibility to primary gouty arthritis

Gouty arthritis is the most common type of inflammatory and immune disease, and the prevalence and incidence of gout increases annually. Genetic variations in the DNA methyltransferases (DNMTs) gene have not, to the best of our knowledge, been reported to influence gene expression and to participate in the pathogenesis of gout. The aim of the present study was to investigate whether the DNMT1, DNMT3A and DNMT3B polymorphisms contribute to gout susceptibility. These polymorphisms were screened for in 336 gout patients and 306 healthy control subjects (from a South China population) for association with gout. The distribution frequencies of DNMT1 rs2228611 AA genotype (P=0.007) and A allele (P=0.002; odds ratio=1.508, 95% confidence interval=1.158-1.964) were found to be significantly increased in the gout patients when compared with those in the healthy control subjects. The rs1550117 in DNMT3A and rs2424913 in DNMT3B exhibited no significant associations with gout susceptibility between the patients and control subjects. These results demonstrated that the DNMT1 rs2228611 polymorphism may be involved in the pathogenesis of gout, while DNMT3A rs1550117 and DNMT3B rs2424913 did not show any obvious significance in the current study; thus, may not be used as risk factors to predict the susceptibility to gout. However, further studies are required to investigate the functions and regulatory mechanism of the polymorphisms of DNMTs in gout.

Advances in the pathophysiology of primary immune thrombocytopenia

OBJECTIVES

Classically, immune thrombocytopenia (ITP) was thought to be caused by the destruction and insufficient production of platelets, as mediated by autoantibodies. More recently other immune mechanisms that contribute to the disease have been discovered. This review attempts to address the main unresolved questions in ITP.

METHODS

We review the most current knowledge of the pathophysiology of ITP. Immunological effects of available therapies are also described.

DISCUSSION

The trigger may be a loss of tolerance due to molecular mimicry with cross-reaction of antibodies arising from infectious agents or drugs, genetic factors, and/or platelet Toll receptors. This loss of tolerance activates autoreactive effector B and T lymphocytes, which in turn initiates platelet destruction, mediated by cytotoxic T lymphocytes and the release of pro-inflammatory cytokines (IL-2/IL-17) by T helper (Th) cells (Th1/Th17). Th2 (anti-inflammatory) and regulatory B (Breg) and Treg cells are also inhibited (with decrease in IL-10/TGF-β), which leads to the disease becoming chronic. Some isotypes of autoantibodies may increase the bleeding risk. Corticosteroids, rituximab, and thrombopoietin receptor agonists (A-TPOs) all increase levels of Tregs and TGF-β. The A-TPOs also increase Breg levels, which could explain why complete remission has been seen in some cases.

CONCLUSION

A better understanding of the immunomodulatory effects of each ITP therapy is needed to best manage the disease.

Gene-gene and gene-sex epistatic interactions of DNMT1, DNMT3A and DNMT3B in autoimmune thyroid disease

The aim of this study was to investigate the associations of DNA methyltransferases (DNMTs) polymorphisms with susceptibility to autoimmune thyroid diseases (AITDs) and to test gene-gene/gene-sex epistasis interactions. Eight single-nucleotide polymorphisms (SNPs) in DNMT1, DNMT3A and DNMT3B were selected and genotyped by multiplex polymerase chain reaction combined with ligase detection reaction method (PCR-LDR). A total of 685 Graves' disease (GD) patients, 353 Hashimoto's thyroiditis (HT) patients and 909 healthy controls were included in the final analysis. Epistasis was tested by additive model, multiplicative model and general multifactor dimensionality reduction (general MDR). Rs2424913 (DNMT3B) and rs2228611 (DNMT1) were associated with susceptibility to AITD and GD in the dominant and overdominant model, respectively (rs2424913: P=0.009 for AITD, P=0.0041 for GD; rs2228611: P=0.035 for AITD, P=0.043 for GD). Multiplicative and multiple high dimensional gene-gene or gene-sex interactions were also observed in this study. We have found evidence for a potential role of rs2424913 (DNMT3B) and rs2228611 (DNMT1) in AITD susceptibility and identified novel gene-gene/gene-sex interactions in AITD. Our study may highlight sex and genes of DNMTs family as contributors to the pathogenesis of AITD.

Maternal risk for down syndrome and polymorphisms in the promoter region of the DNMT3B gene: a case-control study

BACKGROUND

Epigenetic changes leading to improper methylation of the pericentromeric region of chromosome 21 may contribute to the nondisjunction of this chromosome. Polymorphisms in the DNA Methyltransferase 3B (DNMT3B) gene, one of the crucial gene of the folate metabolism, affects the activity of the enzyme and increases the susceptibility of nondisjunction in mothers of Down syndrome children (MDS).

METHODS

Considering this hypothesis we investigated the association of single nucleotide polymorphisms in the promoter region of the DNMT3B gene (rs1569686 -579G>T; rs2424913 -149C>T) with a predisposition of mothers to deliver a Down syndrome (DS) child. The study was performed on DNA samples from 150 MDS and 172 control mothers. Transmission disequilibrium tests were performed on 103 DS trio families. Genotyping was done using a polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

With respect to the single nucleotide polymorphisms studied, no significant difference was observed in the genotypes and alleles frequency distributions between MDS and control mothers. The frequency of the DNMT3B-579G allele was, respectively, 0.34 in MDS and 0.33 in control mothers whereas the frequency of the DNMT3B-149C allele was respectively 0.31 in MDS and 0.26 in control mothers. No significant deviation in genotypic combinations as well as in transmission disequilibrium tests analysis was observed. However, a strong linkage disequilibrium was observed with significant differences in the distribution of G-T and G-C haplotypes among case and control mothers.

CONCLUSION

Although the above studied polymorphisms of DNMT3B may not be an independent risk factor it might be possible that certain allelic combinations (G-T) are. This finding suggests that DNMT3B might be a maternal risk factor for DS in our Indian cohort. Replication studies are required to confirm these findings.

Fatigue in immune thrombocytopenia

Fatigue is an important aspect of health-related quality of life from the patient perspective and can have significant socio-economic consequences. It is a common feature of chronic illnesses and a significant number of both adults and children with immune thrombocytopenia (ITP) suffer from fatigue. Reliable, validated fatigue scales have been developed for use in ITP. These will facilitate future investigation of its pathogenesis and the effectiveness of intervention. Acute inflammation acts on neural and endocrine systems resulting in 'sickness behaviour', an adaptive response to infection and injury. Inflammation is also thought to cause fatigue in chronic disease and immune dysregulation in ITP appears to have a number of pro-inflammatory components. Clinicians should consider fatigue when assessing the burden of disease. Although effective ITP-directed therapy can improve fatigue, a number of fatigue-directed strategies may also need to be considered.

Immune thrombocytopenia: serum cytokine levels in children and adults

Background

Immune thrombocytopenia (ITP) is an immune-mediated platelet disorder in which autoantibody-coated platelets are removed from the blood by monocytic phagocytes and there is impaired platelet production. There is a delicate balance of specific cytokine levels, which has an important role in the immune system and is known to be deregulated in autoimmune diseases. This study was designed to investigate the differences in Th cytokine levels between children and adults with newly diagnosed ITP and to compare these profiles to those found in healthy, age-matched controls.

Material/Methods

The concentration of IL-1α, IL-2, IL-3, IL-4, IL-6, IL-10, TNF-α, IFN-α, and IFN-γ in serum specimens was analyzed by enzyme-linked immunosorbent assay.

Results

At the time of ITP diagnosis, children showed significantly lower serum levels of interleukin IL-2 and tumor necrosis factor TNF-α and higher serum level of IL-3 than healthy controls. Serum level of IL-4 in adult ITP patients was higher than those in control subjects. When compared with adults, children with ITP had lower serum level of IL-4, IL-6 and IFN-γ, and higher level of IFN-α.

Conclusions

Significant differences in serum cytokine levels between pediatric patients and healthy controls indicate that cytokine disturbances – especially changes in IL-2, IL-3 and TNF-α – might be involved in the pathogenesis of newly diagnosed ITP. TNF-α is the most informative variable for discrimination between healthy children and those with ITP.

Immune thrombocytopenia: serum cytokine levels in children and adults

BACKGROUND

Immune thrombocytopenia (ITP) is an immune-mediated platelet disorder in which autoantibody-coated platelets are removed from the blood by monocytic phagocytes and there is impaired platelet production. There is a delicate balance of specific cytokine levels, which has an important role in the immune system and is known to be deregulated in autoimmune diseases. This study was designed to investigate the differences in Th cytokine levels between children and adults with newly diagnosed ITP and to compare these profiles to those found in healthy, age-matched controls.

MATERIAL/METHODS

The concentration of IL-1alpha, IL-2, IL-3, IL-4, IL-6, IL-10, TNF-alpha, IFN-alpha, and IFN-alpha in serum specimens was analyzed by enzyme-linked immunosorbent assay.

RESULTS

At the time of ITP diagnosis, children showed significantly lower serum levels of interleukin IL-2 and tumor necrosis factor TNF-alpha and higher serum level of IL-3 than healthy controls. Serum level of IL-4 in adult ITP patients was higher than those in control subjects. When compared with adults, children with ITP had lower serum level of IL-4, IL-6 and IFN-alpha, and higher level of IFN-alpha.

CONCLUSIONS

Significant differences in serum cytokine levels between pediatric patients and healthy controls indicate that cytokine disturbances--especially changes in IL-2, IL-3 and TNF-alpha--might be involved in the pathogenesis of newly diagnosed ITP. TNF-alpha is the most informative variable for discrimination between healthy children and those with ITP.