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Year : 2017  |  Volume : 30  |  Issue : 3  |  Page : 940-945

Interleukin 10 gene polymorphism and lepra reactions: susceptibility and immunological correlation

1 Department of Dermatology, Andrology and STIs, Menoufia University, Menoufia, Egypt
2 Department of Biochemistry, Faculty of Medicine, Menoufia University, Menoufia, Egypt
3 Department of Dermatology, Albagoor General Hospital, Menoufia, Egypt

Date of Submission27-Sep-2016
Date of Acceptance23-Nov-2016
Date of Web Publication15-Nov-2017

Correspondence Address:
Shaimaa F. G. El-Sayed
Department of Dermatology, Albagoor General Hospital, Albagoor, Menoufia, 32821
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1110-2098.218295

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The aim of the study was to evaluate interleukin 10 (IL-10) gene single nucleotide polymorphisms (SNPs) as a susceptibility gene in lepra reactions.
Leprosy is a chronic dermatoneurological disease, caused by Mycobacterium leprae. Lepra reactions are immune inflammatory-related leprosy phenotypes that may occur before diagnosis of leprosy, during treatment, or after multiple drug therapy. IL-10 gene becomes widely used in studies of immune-mediated disease. It can be a marker of disease susceptibility as well as of disease severity. This work studies IL-10 gene polymorphisms as a susceptibility gene in lepra reactions which may be useful in preventing lepra reactions as a complication of leprosy.
Patients and methods
This study was conducted on 40 patients with leprosy (20 with reactions), who were recruited from the Menoufia Unit of Dermatology and Leprosy within a period of 1 year, in addition to 20 control subjects, without history of leprosy, from the same geographic area. SNPs –1082A/G, –819C/T, and –592 A/C were identified in cases and control groups by PCR-RFLP.
The genotype C/C in the SNP-819 was associated with lepra reaction (P < 0.01). There was no association between –592 A/C (P > 0.05) and 1082A/G (P > 0.05) and lepra reaction. The haplotype –1082A–819C–592C/–1082A–819T-592A is considered a risky haplotype category. The study documents that –1082A–819C–592C/–1082A–819C–592C and –1082A–819T–592A/–1082A–819T–592A are considered protective haplotypes. According to the study, the haplotype – 1082G–819C–592C/–1082A–819C–592C has no effect genetically.
IL-10 gene 819 SNP (C/C) is a risky polymorphism which increases susceptibility to lepra reaction, whereas IL-10 1082 SNP and IL-10 592 SNP are not associated with lepra reactions.

Keywords: haplotypes, interleukin 10, multiple drug therapy, single nucleotide polymorphism

How to cite this article:
Maraee AH, Antar AG, El-Shazly RM, El-Sayed SF. Interleukin 10 gene polymorphism and lepra reactions: susceptibility and immunological correlation. Menoufia Med J 2017;30:940-5

How to cite this URL:
Maraee AH, Antar AG, El-Shazly RM, El-Sayed SF. Interleukin 10 gene polymorphism and lepra reactions: susceptibility and immunological correlation. Menoufia Med J [serial online] 2017 [cited 2020 Jun 6];30:940-5. Available from: http://www.mmj.eg.net/text.asp?2017/30/3/940/218295

  Introduction Top

Leprosy is a contagious infectious disabling disease caused by Mycobacterium leprae that affects peripheral nerves; three forms may appear: tuberculoid (TT), lepromatous (LL), and borderline [1].

Leprosy reactions are defined as one of the acute episodes of chills, fever, malaise, and skin eruption occurring in the long-term course of leprosy. Leprosy reactions require immediate treatment to prevent permanent nerve impairment, motor disability, and deformity [2].

Genetic studies of M. leprae strains showed that there are differences in susceptibility to leprosy disease and its clinical manifestations, including lepra reaction episodes either type I or type II, and this difference is influenced by the host defense gene [3].

Interleukin 10 gene(IL-10) is one of the immunoregulatory cytokine genes that contribute to the immune response, which is translated in control or persistence of the pathogens including M. lepra [4].

IL-10 single nucleotide gene polymorphisms have been reported as a marker for leprosy and lepra reactions susceptibility, demonstrating an important gene-leprosy association, sometimes as risky gene or as a protective one [5].

  Patients and Methods Top

The study was conducted on 40 patients with leprosy, including 20 cases with lepra reactions, who were recruited from the Menoufia Unit of Dermatology and Leprosy from the period between February 2014 and February 2015, with an age ranged from 23 to 65 years. Diagnosis of cases was based on clinical and histopathological criteria of leprosy disease. In addition, 20 age-matched and sex-matched healthy volunteers, with negative family history of leprosy, from the same geographic area, were recruited in the study as well, as a control group.

After taking a written consent, all studied cases were subjected to complete history taking and clinical and dermatological examination, according to the Research Ethics Committee of Menoufia University.

Blood sample was taken from all subjects in the study, and then evaluation of IL-10 gene polymorphisms (genotyping) was done by polymerase chain reaction PCR-RFLP (i.e. peripheral blood mononuclear cells isolation was performed, and then DNA was extraction by commercially available spin column technique kit, after that PCR was done for IL-10 gene using primers: primer F and primer R, then detection of IL-10 gene was done by gel electrophoresis, and lastly, IL-10 gene typing was done by using restriction enzymes technique) [6].

Statistical analysis

The results were collected, tabulated, and analyzed by statistical package for social science (SPSS, version 17.0) on IBM compatible computer (SPSS, Chicago, Illinois, USA).

Two types of statistics were done: descriptive statistics (e.g. percentage, mean, and SD), and analytic statistics, which include the following tests:

  • χ2, which was used to study the association between two qualitative variables
  • Odds ratio (OR), which is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome occurring in a particular exposure compared with the odds of the outcome occurring in the absence of that exposure.

P value of less than 0.05 was considered statistically significant.

  Results Top

The results showed that IL-10 gene 819 T/C polymorphism was significantly associated with patients with lepra reaction than the control group [Table 1].
Table 1: Comparing total cases and controls regarding interleukin 10 819 T/C single nucleotide polymorphism

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There was no significant association between leprosy cases, lepra reaction, and control groups regarding IL-10 1082A/G polymorphisms [Table 2].
Table 2: Comparing total cases and controls regarding interleukin 10 1082A/G single nucleotide polymorphism

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There was no significant association between leprosy cases without reaction, lepra reaction cases, and control group regarding IL-10 592C/A gene polymorphisms [Table 3].
Table 3 Comparing total cases and controls regarding interleukin 10 592C/A single nucleotide polymorphism

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The haplotype –1082A–819C–592C/–1082A–819T–592A (ACC/ATA) was considered a risky one, with 2.5 folds risk to develop the disease in its carriers (OR = 2.5).

The haplotype –1082A–819C–592C/–1082A–819C–592C (ACC/ACC) was considered as protective, with OR of 0.37; moreover, –1082A–819T–592A/–1082A–819T–592A (ATA/ATA) and –1082G–819C–1082C/–1082G–819C–592C (GCC/GCC) were also considered protective haplotypes, with ORs of 0.30 and 0.38, respectively, according to this study [Table 4].
Table 4: Comparing between cases and controls regarding haplotypes

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  Discussion Top

Leprosy is a chronic granulomatous infectious disease caused by M. leprae. The disease predominantly affects the skin, nerves, and cooler parts of the body [7].

Leprosy reactions are immune inflammatory-related phenotypes; they are episodes of acute inflammation in leprosy lesions, in nerves, and other body parts and are characteristic aspects of Hansen's disease that may occur before diagnosis, during treatment, or after multiple drug therapy. Leprosy reactions require immediate treatment to prevent permanent nerve impairment, motor disability, and deformity. It is a common reason for patients to seek consultation [8].

IL-10 is one of the cytokines secreted by monocyte, macrophage, and T cells lineage. IL-10 induces the production of anti-inflammatory mediators. It inhibits the release of various chemokines by neutrophils, and it regulates T-helper 1 cytokines production, contributing to the immune response, which is translated into control or persistence of the pathogens, including M. leprae [9].

There are clinical and epidemiological evidences suggesting that leprosy does not occur in most of the exposed individuals; this fact can be partly explained by their genetic background, implicating the participation of immune response genes [10].

The aim of the present work was to study the association between IL-10 gene polymorphisms with leprosy including lepra reactions.

To elucidate this aim, 40 patients with leprosy (including lepra reactions) versus 20 control persons were enrolled in this study.

In this study, a higher prevalence of IL-10 819 T/C gene polymorphisms was detected in patients with lepra reaction compared with that in control group [Table 1], suggesting that carriers of this IL-10 gene single nucleotide polymorphism may have an increased risk of having leprosy disease and its reactions. This result coincides with the results of an earlier study done on Colombian population (100 cases and 100 controls) [11]. When the study was done on ethnic group from Brazilian population, different results appeared, which found that IL-10 819 T/C genotype polymorphisms were not associated with lepra reaction occurrence among patients [12]. The same results were found in other studies done on an Indian sample by Malhotra et al. [13] and on a Chinese sample by Pereira et al. [14].

This means that the genotypes of IL-10 and its single nucleotide polymorphisms are present at different frequencies in geographically separated populations, suggesting that genetic heterogeneity may be one of the reasons for the difficulty in drawing similar conclusions about susceptibility genes across populations [15].

Regarding IL-10 1082A/G gene polymorphism in the current study, it showed no significant difference between cases and control [Table 2]. These results are in agreement with the findings of the study performed by Alcaïs et al. [16] and found that the IL-10 1082A/G genotype has no significant association between cases and controls.

On the other hand, the current results were different from the findings of the study by Bleharsky et al. [17] done on Malawian population and that done by Arany et al. [18]; they found that there was a significant association between cases and controls regarding the IL-10 1082A/G genotype polymorphism, and this was a risky gene among patients in those studies.

Differences in genotypes prevalence in different studies may be because of different study design, different ethnic background of patients and controls, and different sample sizes or distribution of leprosy and lepra reaction subtypes [19].

In the current study, regarding IL-10 592C/A gene polymorphisms, no statistically significant association between cases and controls was found [Table 3].

In contrast to this study, there was an earlier study done by D'Alfonoso et al. [20] on South Indian population that found there was a significantly higher frequency of IL-10 592C/A polymorphisms in patients with leprosy compared with control group.

In the current study, comparison between leprosy cases and control groups regarding haplotypes, which are a group of genes in an organism that are inherited together from a single parent [Table 4], showed that –1082A–819C–592C/–1082A–819T–592A (ACC/ATA) is considered a risky haplotype category, which is associated with 2.5 folds greater risk of developing the disease and increases the disease susceptibility among people who carry this haplotype. This is because this haplotype is a high producer of IL-10 genes [21].

Also the current study recorded that –1082A–819C–592C/–1082A–819C–592C (ACC/ACC) and –1082A–819T–592A/–1082A–819T–592A (ATA/ATA) are protective haplotypes, and these haplotypes are low producers of IL-10 gene. Functionally, this low production of IL-10 may have an immune response consequences and clinical implications to protect from developing the disease, with an evidence to induce immune response toward the disease.

The same was recorded with –1082G–819C–1082C/–1082G–819C–592C (GCC/GCC), it is considered as a protective haplotype. But regarding –1082G–819C–592C/–1082A–819C–592C (GCC/ACC) haplotype, this study found that it has no effect genetically.

Conflicting with our data, earlier data reported by Fitness et al. [22] on the haplotypes study done on 45 patients with lepra reaction cases and 30 controls revealed that –1082T–819G–592A/–1082C–819T–592C (TGA/CTC) is the risky haplotype with 4.5 folds increase in the disease susceptibility and –1082T–819G–592C/–1082A–819T–592A (TGC/ATA) as a protective haplotype with resistance to develop the disease in people who produce this haplotype.

Also another study disagreed with this study, which was done by Pereira et al. [14] on a sample of Brazilian population (300 lepra reaction cases and 200 control); they found that –1082A–819C–592C/–1082A–819T–592A (ACC/ATA) was a risky haplotype with ~six-fold increase in the susceptibility of the lepra reaction disease. Also, they found that 1082T–819G–592A/–1082C–819T–592C (TGA/CTC) is a protective haplotype with low production of IL-10 and that immune response developed in people with that haplotype.

The variability in haplotypes of IL-10 associated with leprosy in different ethnic groups can be explained by genetic ancestry of the populations; because the African population shows a more widespread distribution of IL-10 haplotypes, they acquire a higher susceptibility to leprosy than the White and Asian populations [19]. Therefore, our hypothesis of a correlation between genetic factors and susceptibility suggests that an increased African component in the ancestry of patients with leprosy indicates a high frequency of genes that influence host susceptibility for disease.

Identification of the patients' genes that influence susceptibility/resistance of the people to leprosy and lepra reaction will enable a greater understanding of disease pathogenesis, and in turn, this will facilitate the development of more effective and specific therapeutics and vaccines and may play an important role in the global elimination of leprosy [23].

  Conclusion Top

IL-10 gene 819 T/C polymorphisms is a risky gene polymorphism for leprosy and lepra reactions, whereas 1082A/G and 592C/A are not associated with leprosy or lepra reaction.

Also the haplotype –1082A–819 C–592C/–1082A–819T-592A (ACC/ATA) is considered as a risky haplotype, whereas the haplotypes –1082A–819C–592C/–1082A–819C–592C (ACC/ACC), –1082A–819T–592A/–1082A–819T–592A (ATA/ATA), and –1082G–819C–1082C/–1082G–819C–592C (GCC/GCC) are considered protective haplotypes.

The study recommends further studies on larger scales and more extended samples to validate and expand the current findings in Egyptian patients with leprosy and lepra reaction, and also the possible role of other IL-10 gene polymorphisms in leprosy and its complication including reactions, so as to help in the eradication and prophylaxis of this disabling disease.

Also, clinical trials are needed to evaluate the value of IL-10 gene as a therapeutic target in leprosy and lepra reactions.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Table 1], [Table 2], [Table 3], [Table 4]


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