Introduction

Transplantation is currently the treatment of choice for end-stage insufficiency of various organs and severe hematologic disorders. Cytokine gene polymorphisms have been extensively explored in transplantation because they are thought to possibly explain the heterogeneity of courses and outcomes and to help in immunosuppression individualization. Although many polymorphisms have been described in the IL-10 gene, the -1082 single nucleotide polymorphism is the most investigated in transplantation. Furthermore, acute rejection is the endpoint most frequently used in cytokine gene polymorphisms studies in organ transplantation. It appears that factors such as effect of HLA and minor histocompatibility mismatch, type of donor, and type of immunosuppression are important to determine the influence of IL-10 gene polymorphisms on transplant outcome. Although there are several discrepancies between the results of studies of IL-10 gene polymorphisms and transplant outcome, it seems that recipient's IL-10 polymorphisms may indicate the severity of acute graft versus host disease in bone marrow transplantation, frequency of acute rejection in organ transplantation and even could be associated with long-term renal graft outcome. In conclusion, data collected up to now demonstrate substantial evidence of IL-10 gene polymorphism involvement in post-transplant outcome. Multi-centric prospective studies using multi-locus approaches might ascertain when and how IL-10 genotype information should be considered in clinical transplant practice.

Transplantation and Cytokine Polymorphisms

Transplantation is currently the treatment of choice for end-stage insufficiency of various organs and severe hematologic disorders. Despite high short-term survival rates for most of the transplants, long-term results still need to be improved. Among different possibilities for improvement of transplant outcome, the individualization of immunosuppression therapy and tolerance induction seem to be the most promising ones.

Regulated by different cytokines, the post-transplant immune response is a very important variable influencing graft outcome. Thus, any variations in cytokine levels may directly influence the course of transplant. Therefore, cytokine gene polymorphisms have been extensively explored in transplantation because they are thought to possibly explain the heterogeneity of courses and outcomes and to help in immunosuppression adjustment.

Why Study Gene Polymorphisms of IL-10?

In studies with twins, it has been suggested that 50-75% of the variation in IL-10 production is genetically determined.^1,2 Although the basis for heritable differences has not been completely defined, the polymorphisms located within and around the IL-10 gene have been implicated. Indeed, variations in the distal and proximal IL-10 gene promoter regions were shown to be associated with transcriptional activity and/or production of IL-10.^3-8

Which IL-10 Polymorphisms Are Usually Analyzed in Transplantation?

Although many single nucleotide polymorphisms (SNPs) and microsatellites have been described in the IL-10 gene, the SNP at -1082 position is the polymorphism most frequently investigated in transplantation. SNPs at the -819, -592 positions and microsatellites at the -1064 position are also popular, while SNPs in the distal 5' promoter region and other microsatellites are rarely analyzed.

Which Follow-Up Parameters Are Usually Analyzed?

Several parameters are used to evaluate the transplant follow-up. They include incidence and severity of acute and chronic rejection, graft and patient survival, occurrence of infection episodes, and cancer. There are also particular parameters for a given type of transplantation, like Graft Versus Host Disease (GVHD) in hematopoietic stem cell transplantation, or functional characteristics specific for each organ. Acute rejection is the endpoint most frequently used in cytokine gene polymorphisms studies in organ transplantation.

IL-10 Polymorphisms in Different Transplant Models

Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation, which includes the use of bone marrow, cord blood, or peripheral blood stem cells, can cure many patients with a variety of hematologic malignancies and nonmalignant bone marrow failure syndromes. The major complication of this type of transplantation is acute GVHD (aGVHD), which is caused by the immune response of the injected allograft against the recipient's tissues and is characterized by the presence of dermatitis, hepatitis, and gastroenteritis developing within the first 100 days after transplantation. Lesions in the same organs, occurring more than 100 days after transplantation, are called chronic GVHD.⁹ The level of IL-10 was shown to be associated with the development of aGVHD and even demonstrated a predictive value. Indeed, two groups independently observed an association between increased pretransplant production of IL-10 and low incidence of aGVHD.^10,11 Furthermore, the therapeutic use of this cytokine has been suggested as an additional or alternative prophylaxis for GVHD.¹²

Promising results were obtained in the first study on IL-10 polymorphism in bone marrow transplantation with HLA-identical donors. The authors analyzed the -1064 dinucleotide CA repeat of the IL-10 gene. An increased frequency of alleles with 12 to 16 repeats was found in the group of recipients with more severe aGVHD.¹³ This finding was confirmed in two other independent groups of patients by the same investigators (Table 1).^14,15 In contrast, no similar association was observed in Japanese patients who received transplants from related or unrelated donors.¹⁶

Table 1

IL-10 gene polymorphisms in renal transplantation.

In a more recent study of transplants involving sibling and unrelated donors, Nordlander and collaborators¹⁷ reported that patients homozygous for the IL-10 -1064 allele 13 showed an increased risk of developing grade II-IV aGVHD compared to all other patients. Even though these investigators did not find exactly the same phenomenon as demonstrated previously, their results agreed with the initial studies. In contrast to HLA-identical sibling bone marrow transplantation, in mismatched unrelated cord blood transplantation IL-10 -1064 alleles were not associated with aGVHD (Table 1).¹⁸

Another widely explored IL-10 polymorphism is -1082 G/A. The data regarding this SNP are controversial. Although three studies did not show any relation of this SNP to aGVHD,^14,17,19 a group from France reported association between G/G genotype and severity of aGVHD (Table 1).^20,21 There is also no agreement between the results of three studies that analyzed chronic GVHD in relation to IL-10 polymorphisms.^14,16,21

Briefly, studies conducted on bone marrow transplantation have shown that factors such as effect of HLA mismatch, type of donor (siblings or unrelated subjects), type of GVHD prophylaxis, and minor histocompatibility are important to determine the influence of cytokine gene polymorphisms on transplant outcome. It seems that recipient's IL-10 -1064 alleles may indicate the severity of aGVHD in HLA-identical sibling bone marrow transplantation, while there is no consensus about other IL-10 polymorphisms.

Kidney

Renal transplantation is a widely used therapy for patients with end-stage renal insufficiency. An important cause of morbidity early after renal transplantation is acute allograft rejection, which is induced by the immune response of the recipient against the transplanted organ and leads to allograft deterioration and functional insufficiency.

Increased IL-10 intragraft expression was shown during acute rejection.^22,23 It is interesting to note that, although the strong candidates to produce IL-10 in the graft are cells from the mononuclear infiltrate, it is possible that graft cells could also contribute to the increased IL-10 levels during rejection. This raises the idea of the analysis not only of recipient's but also of donor's genotypes, as well as a combination of both. In contrast to bone marrow transplantation, the most frequently studied IL-10 polymorphism in renal transplantation is -1082 SNP. Table 2 summarizes the results of IL-10 polymorphisms genetic association studies in renal transplantation.

Table 2

IL-10 gene polymorphisms in renal transplantation.

The IL-10 -1082 G/G genotype (corresponding to the high producer phenotype in vitro) was associated with an increase in the incidence of multiple acute rejection episodes in recipients with HLA-DR-mismatched transplants.²⁴ In the cited study, the same genotype was associated with the severity of acute rejection in combination with TNF -308 high production genotype. Similar results were obtained by a Chinese group that observed a higher incidence of rejection in recipients with high/intermediate IL-10 producer genotypes.²⁵ In agreement, Pelletier and colleagues²⁶ reported that a combination of TNF low and IL-10 high producer genotypes was an indicator of increased frequency of acute rejection. On the other hand, in an African American population the -1082 A/A genotype (low producer) alone was associated with the absence of acute rejection.²⁷

In contrast, in another study, the -1082 A/A genotype was more frequent in the group of rejectors than in the group free of rejection.²⁸ A similar finding was also reported by Poole and colleagues,²⁹ who observed a tendency to a higher frequency of rejection in recipients with -1082 A/A and A/G genotypes. Other studies did not show any association between -1082 SNP and acute rejection. ^30,31,32,33

The only study of -1064 microsatellite in renal transplantation with living related haplo-identical donors demonstrated a marked difference in the frequencies of the allele with 12 repeats between rejectors and nonrejectors, with an increase in this difference observed in a subgroup of steroid-resistant rejections.³⁴

Some studies have explored the effect of donor (graft) polymorphisms on transplant outcome. Neither -1082 SNP nor -1064 repeat polymorphism was shown to be associated with acute renal rejection in three studies.^24,34,35 However, in the study of Poole and colleagues,²⁹ -1082 A donor allele frequency was decreased in multiple rejectors with HLA-DR mismatch. In addition, the combination of recipient -1082A negative/donor -1082A positive (recipient high producer/donor low producer) was also significantly decreased in multiple rejectors but independently of HLA match.²⁹

Other parameters whose evaluation could be even more important than incidence of acute rejection in renal transplants are long-term graft function and patient and graft survival. Unfortunately, up to now only a few studies have explored these endpoints. Three studies that analyzed 3 and/or 5 years graft survival did not observe any association with IL-10 polymorphisms at -1082.^24,32,36 However, an increased frequency of the -1082 A/A genotype was demonstrated in the group of patients with graft survival of more than 15 years compared to patients transplanted more recently.³³

Finally, it is worth citing an interesting single study that explored the relationship between skin cancer after renal transplantation and IL-10 SNPs.³⁷ In fact, the investigators demonstrated the association of skin squamous cell carcinoma with the presence of -1082, -819, -592 GCC haplotype, as well as with higher IL-10 production in vitro by the individuals that possessed this marker.

Discussion

Conclusion

In conclusion, data collected up to now demonstrate substantial evidence of IL-10 gene polymorphism involvement in post-transplant outcome. Multi-centric prospective studies using multi-locus approaches might ascertain when and how IL-10 genotype information should be considered in clinical transplant practice.

References

1.

Westendorp RG, Langermans JA, Huizinga TW. et al. Genetic influence on cytokine production and fatal meningococcal disease. Lancet. 1997:349–353. [PubMed: 9111542]

2.

Reuss E, Fimmers R, Kruger A. et al. Differential regulation of interleukin-10 production by genetic and environmental factors-a twin study. Genes Immun. 2002;3:407–413. [PubMed: 12424622]

3.

Turner DM, Williams DM, Sankaran D. et al. An investigation of polymorphism in the interleukin-10 gene promoter. Eur J Immunogenet. 1997;24:1–8. [PubMed: 9043871]

4.

Eskdale J, Gallagher G, Verweij CL. et al. Interleukin 10 secretion in relation to human IL-10 locus haplotypes. Proc Natl Acad Sci USA. 1998;95:9465–9470. [PMC free article: PMC21361] [PubMed: 9689103]

5.

Crawley E, Kay R, Sillibourne J. et al. Polymorphic haplotypes of the interleukin-10 5' flanking region determine variable interleukin-10 transcription and are associated with particular phenotypes of juvenile rheumatoid arthritis. Arthritis Rheum. 1999;42:1101–1108. [PubMed: 10366102]

6.

Lim S, Crawley E, Woo P. et al. Haplotype associated with low interleukin-10 production in patients with severe asthma. Lancet. 1998;352:113. [PubMed: 9672280]

7.

Gibson AW, Edberg JC, Wu J. et al. Novel single nucleotide polymorphisms in the distal IL-10 promoter affect IL-10 production and enhance the risk of systemic lupus erythematosus. J Immunol. 2001;166:3915–3922. [PubMed: 11238636]

8.

Suarez A, Castro P, Alonso R. et al. Interindividual variations in constitutive interleukin-10 messenger RNA and protein levels and their association with genetic polymorphisms. Transplantation. 2003;75:711–717. [PubMed: 12640314]

9.

Goker H, Haznedaroglu IC, Chao NJ. Acute graft-vs-host disease: Pathobiology and management. Exp Hematol. 2001;29:259–277. [PubMed: 11274753]

10.

Holler E, Roncarolo MG, Hintermeier-Knabe R. et al. Prognostic significance of increased IL-10 production in patients prior to allogeneic bone marrow transplantation. Bone Marrow Transplant. 2000;25:237–241. [PubMed: 10673693]

11.

Ju X, Wang J, Xu B. et al. Roles of interleukin-10 in acute graft-versus-host disease and graft rejection. Chin Med J. 2003;116:534–537. [PubMed: 12875717]

12.

Wang XN, Lange C, Schulz U. et al. Interleukin-10 modulation of alloreactivity and graft-versus-host reactions. Transplantation. 2002;74:772–778. [PubMed: 12364854]

13.

Middleton PG, Taylor PR, Jackson G. et al. Dickinson Cytokine gene polymorphisms associating with severe acute graft-versus-host disease in HLA-identical sibling transplants. Blood. 1998;92:3943–3948. [PubMed: 9808588]

14.

Cavet J, Middleton PG, Segall M. et al. Recipient tumor necrosis factor-alpha and interleukin-10 gene polymorphisms associate with early mortality and acute graft-versus-host disease severity in HLA-matched sibling bone marrow transplants. Blood. 1999;94:3941–3946. [PubMed: 10572111]

15.

Cavet J, Dickinson AM, Norden J. et al. Interferon-gamma and interleukin-6 gene polymorphisms associate with graft-versus-host disease in HLA-matched sibling bone marrow transplantation. Blood. 2001;98:1594–1600. [PubMed: 11520812]

16.

Takahashi H, Furukawa T, Hashimoto S. et al. Contribution of TNF-alpha and IL-10 gene polymorphisms to graft-versus-host disease following allo-hematopoietic stem cell transplantation. Bone Marrow Transplant. 2000;26:1317–1323. [PubMed: 11223972]

17.

Nordlander A, Uzunel M, Mattsson J. et al. The TNFd4 allele is correlated to moderate-to-severe acute graft-versus-host disease after allogeneic stem cell transplantation. Br J Haematol. 2002;119:1133–1136. [PubMed: 12472598]

18.

Kogler G, Middleton PG, Wilke M. et al. Recipient cytokine genotypes for TNF-alpha and IL-10 and the minor histocompatibility antigens HY and CD31 codon 125 are not associated with occurrence or severity of acute GVHD in unrelated cord blood transplantation: A retrospective analysis. Transplantation. 2002;74:1167–1175. [PubMed: 12438965]

19.

Tambur AR, Yaniv I, Stein J. et al. Cytokine gene polymorphism in patients with graft-versus-host disease. Transplant Proc. 2001;33:502–503. [PubMed: 11266928]

20.

Socie G, Loiseau P, Tamouza R. et al. Both genetic and clinical factors predict the development of graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. Transplantation. 2001;72:699–706. [PubMed: 11544434]

21.

Rocha V, Franco RF, Porcher R. et al. Host defense and inflammatory gene polymorphisms are associated with outcomes after HLA-identical sibling bone marrow transplantation. Blood. 2002;100:3908–3918. [PubMed: 12393699]

22.

Xu GP, Sharma VK, Li B. et al. Intragraft expression of IL-10 messenger RNA: A novel correlate of renal allograft rejection. Kidney Int. 1995;48:1504–1507. [PubMed: 8544407]

23.

Strehlau J, Pavlakis M, Mark Lipman. et al. Quantitative detection of immune activation transcripts as a diagnostic tool in kidney transplantation. Proc Natl Acad Sci USA. 1997;94:695–700. [PMC free article: PMC19576] [PubMed: 9012847]

24.

Sankaran D, Asderakis A, Ashraf S. et al. Cytokine gene polymorphisms predict acute graft rejection following renal transplantation. Kidney Int. 1999;56:281–288. [PubMed: 10411704]

25.

Tian Y, Ma W, Zhang Y. Influence of cytokine gene polymorphism on renal transplantation. Zhonghua Wai Ke Za Zhi. 2002;40:256–258. [PubMed: 12133353]

26.

Pelletier R, Pravica V, Perrey C. et al. Evidence for a genetic predisposition towards acute rejection after kidney and simultaneous kidney-pancreas transplantation. Transplantation. 2000;70:674–680. [PubMed: 10972228]

27.

Hutchings A, Guay-Woodford L, Thomas JM. et al. Association of cytokine single nucleotide polymorphisms with B7 costimulatory molecules in kidney allograft recipients. Pediatr Transplant. 2002;6:69–77. [PubMed: 11906646]

28.

George S, Turner D, Reynard M. et al. Significance of cytokine gene polymorphism in renal transplantation. Transplant Proc. 2001;33:483–484. [PubMed: 11266919]

29.

Poole KL, Gibbs PJ, Evans PR. et al. Influence of patient and donor cytokine genotypes on renal allograft rejection: Evidence from a single centre study. Transpl Immunol. 2001;8:259–265. [PubMed: 11316069]

30.

Marshall SE, McLaren AJ, Haldar NA. et al. The impact of recipient cytokine genotype on acute rejection after renal transplantation. Transplantation. 2000;70:1485–1491. [PubMed: 11118095]

31.

Hahn AB, Kasten-Jolly JC, Constantino DM. et al. TNF-alpha, IL-6, IFN-gamma, and IL-10 gene expression polymorphisms and the IL-4 receptor alpha-chain variant Q576R: Effects on renal allograft outcome. Transplantation. 2001;72:660–665. [PubMed: 11544427]

32.

Asderakis A, Sankaran D, Dyer P. et al. Association of polymorphisms in the human interferon-gamma and interleukin-10 gene with acute and chronic kidney transplant outcome: The cytokine effect on transplantation. Transplantation. 2001;71:674–677. [PubMed: 11292301]

33.

Poli F, Boschiero L, Giannoni F. et al. TNF-alpha IFN-gamma IL-6, IL-10, and TGF-beta1 gene polymorphisms in renal allografts. Transplant Proc. 2001;33:348–349. [PubMed: 11266855]

34.

Kobayashi T, Yokoyama I, Hayashi S. et al. Genetic polymorphism in the IL-10 promoter region in renal transplantation. Transplant Proc. 1999;31:755–756. [PubMed: 10083323]

35.

Marshall SE, McLaren AJ, McKinney EF. et al. Donor cytokine genotype influences the development of acute rejection after renal transplantation. Transplantation. 2001;71:469–476. [PubMed: 11233912]

36.

Mytilineos J, Opelz G. Impact of cytokine gene single nucleotide polymorphisms (SNP) in kidney transplant recipients. Transplantation. 2002;74:43.

37.

Alamartine E, Berthoux P, Mariat C. et al. Interleukin-10 promoter polymorphisms and susceptibility to skin squamous cell carcinoma after renal transplantation. J Invest Dermatol. 2003;120:99–103. [PubMed: 12535204]

38.

Shinozaki K, Yahata H, Tanji H. et al. Allograft transduction of IL-10 prolongs survival following orthotopic liver transplantation. Gene Ther. 1999;6:816–822. [PubMed: 10505106]

39.

Platz KP, Mueller AR, Rossaint R. et al. Cytokine pattern during rejection and infection after liver transplantation-improvements in postoperative monitoring? Transplantation. 1996;62:1441–1450. [PubMed: 8958270]

40.

Conti F, Boulland ML, Leroy-Viard K. et al. Low level of interleukin 10 synthesis during liver allograft rejection. Lab Invest. 1998;78:1281–1289. [PubMed: 9800954]

41.

Minguela A, Torio A, Marin L. et al. Implication of soluble and membrane HLA class I and serum IL-10 in liver graft acceptance. Hum Immunol. 1999;60:500–509. [PubMed: 10408799]

42.

Bathgate AJ, Pravica V, Perrey C. et al. Polymorphisms in tumour necrosis factor alpha, interleukin-10 and transforming growth factor beta1 genes and end-stage liver disease. Eur J Gastroenterol Hepatol. 2000;12:1329–1333. [PubMed: 11192323]

43.

Jonsson JR, Hong C, Purdie DM. et al. Role of cytokine gene polymorphisms in acute rejection and renal impairment after liver transplantation. Liver Transpl. 2001;7:255–263. [PubMed: 11244168]

44.

Fernandes H, Koneru B, Fernandes N. et al. Investigation of promoter polymorphisms in the tumor necrosis factor-alpha and interleukin-10 genes in liver transplant patients. Transplantation. 2002;73:1886–1891. [PubMed: 12131682]

45.

Warle MC, Farhan A, Metselaar HJ. et al. Cytokine gene polymorphisms and acute human liver graft rejection. Liver Transpl. 2002;8:603–611. [PubMed: 12089714]

46.

Tambur AR, Ortegel JW, Ben-Ari Z. et al. Role of cytokine gene polymorphism in hepatitis C recurrence and allograft rejection among liver transplant recipients. Transplantation. 2001;71:1475–1480. [PubMed: 11391238]

47.

Mazariegos GV, Reyes J, Webber SA. et al. Cytokine gene polymorphisms in children successfully withdrawn from immunosuppression after liver transplantation. Transplantation. 2002;73:1342–1345. [PubMed: 11981433]

48.

Turner DM, Grant SC, Lamb WR. et al. A genetic marker of high TNF-alpha production in heart transplant recipients. Transplantation. 1995;60:1113–1117. [PubMed: 7482718]

49.

Turner D, Grant SC, Yonan N. et al. Cytokine gene polymorphism and heart transplant rejection. Transplantation. 1997;64:776–779. [PubMed: 9311720]

50.

Awad MR, Webber S, Boyle G. et al. The effect of cytokine gene polymorphisms on pediatric heart allograft outcome. J Heart Lung Transplant. 2001;20:625–630. [PubMed: 11404167]

51.

Morgun A, Shulzhenko N, Rampim GF. et al. Influence of cytokine genetic polymorphisms on cardiac transplant outcome. In: Hansen JA, Dupont B, eds. HLA 2002, Immunobiology of the human MHC. Seattle, WA: IHWG press, in press.

52.

Bijlsma FJ, Bruggink AH, Hartman M. et al. No association between IL-10 promoter gene polymorphism and heart failure or rejection following cardiac transplantation. Tissue Antigens. 2001;57:151–153. [PubMed: 11260510]

53.

Densem CG, Hutchinson IV, Yonan N. et al. Influence of interleukin-10 polymorphism on the development of coronary vasculopathy following cardiac transplantation. Transpl Immunol. 2003;11:223–228. [PubMed: 12799207]

54.

Lu KC, Jaramillo A, Lecha RL. et al. Interleukin-6 and interferon-gamma gene polymorphisms in the development of bronchiolitis obliterans syndrome after lung transplantation. Transplantation. 2002;74:1297–12302. [PubMed: 12451269]

55.

Daly AK, Day CP. Candidate gene case-control association studies: Advantages and potential pitfalls. Br J Clin Pharmacol. 2001;52:489–499. [PMC free article: PMC2014606] [PubMed: 11736857]

56.

Cardon LR, Palmer LJ. Population stratification and spurious allelic association. Lancet. 2003;361:598–604. [PubMed: 12598158]

57.

Colhoun HM, McKeigue PM, Davey SmithG. Problems of reporting genetic associations with complex outcomes. Lancet. 2003;361:865–872. [PubMed: 12642066]

58.

Lio D, Scola L, Crivello A. et al. Gender-specific association between -1082 IL-10 promoter polymorphism and longevity. Genes Immun. 2002;3:30–33. [PubMed: 11857058]

59.

Hariharan S, McBride MA, Cohen EP. Evolution of endpoints for renal transplant outcome. Am J Transplant. 2003;3:933–941. [PubMed: 12859527]

60.

Hoh J, Ott J. Mathematical multi-locus approaches to localizing complex human trait genes. Nat Rev Genet. 2003;4:701–709. [PubMed: 12951571]

61.

Gasche C, Grundtner P, Zwirn P. et al. Novel variants of the IL-10 receptor 1 affect inhibition of monocyte TNF-alpha production. J Immunol. 2003;170:5578–5582. [PubMed: 12759436]