The impact of donor cytokine gene polymorphisms on the incidence of cytomegalovirus infection after kidney transplantation

Human genetic polymorphisms and risk of viral infection after solid organ transplantation

The immune system plays a key role in the host defense against viral pathogens. A signaling cascade is activated upon infection involving a variety of molecules such as pattern-recognition receptors (PRRs), interleukins or antiviral interferons. Long-term immunosuppression after solid organ transplantation (SOT) mainly abrogates adaptive T-cell-mediated responses, thus highlighting the relative contribution of innate immunity. Single-nucleotide polymorphisms (SNPs) within genes coding for PRRs or soluble mediators have been associated with differential susceptibility to viral infections among SOT recipients. A protective effect against cytomegalovirus (CMV) infection or disease has been attributed to certain SNPs in TLR9 or IFNL3 genes, whereas the opposite effect has been attributed to genetic polymorphisms in TLR2, MBL2, DC-SIGN, IL10 or IFNG. The presence of SNPs in other molecules not directly involved in innate or adaptive immune responses such as aquaporins or pregnane X appear to modulate the risk of CMV or BK polyomavirus infection, respectively. Little information is available on the genetic determinants of the post-transplant susceptibility to herpesviruses causing clinical infection (herpes simplex virus or varicella zoster virus) or the replication kinetics of components of the human blood virome used as immune surrogates (Torque teno virus). The present review critically summarizes the current knowledge on how SNP genotyping would be useful to stratify SOT recipients according to the individual risk of viral infection and proposes next research steps. Genetic susceptibility testing may improve personalized medicine and contribute to minimize the risk of viral infection after SOT.

The Interferon-Gamma +874 A/T Polymorphism Is Not Associated With CMV Infection After Kidney Transplantation

The +874 A/T polymorphism in the interferon gamma (IFNG) gene has been associated with Cytomegalovirus (CMV) infection risk in lung and kidney transplant recipients. To replicate this association, we performed a retrospective observational study of this polymorphism and immunosuppressive therapies considering the prophylactic treatment in 600 consecutive kidney transplanted recipients. We found no association of the aforementioned polymorphism with CMV infection in univariate and multivariate analyses regardless of the prophylactic treatment. In addition, the immunosuppressive treatment with mammalian target of rapamycin inhibitors (imTOR) showed a protective effect in all patients independently of prophylaxis. Moreover, in the adjusted model, we found interactions between prophylaxis with high-risk (Donor+/Recipient-, D+/R-) status (p-interaction = 0.01), with thymoglobulin induction therapy (p-interaction = 0.03) and with thymoglobulin anti-rejection therapy (p-interaction = 0.002). Data also revealed that prophylaxis was not an advantage in the not D+/R- and without thymoglobulin therapy group (HR = 0.98, p = 0.95). The benefit of prophylaxis was observed in all groups with thymoglobulin therapy, but it was maximal in the high-risk CMV infection group with both thymoglobulin induction therapy and thymoglobulin anti-rejection therapy (HR = 0.01, p < 0.001). In conclusion, the IFNG +874 polymorphism is not a predictive marker of CMV infection. The protective effect of imTOR is not improved with prophylaxis. Interestingly, the thymoglobulin therapy associated with prophylaxis is not a risk factor for CMV infection, and prophylaxis is not effective in recipients with no high-risk CMV status and without thymoglobulin therapy.

Host Genetics of Cytomegalovirus Pathogenesis

Human cytomegalovirus (HCMV) is a ubiquitous herpes virus (human herpes virus 5) with the highest morbidity and mortality rates compared to other herpes viruses. Risk groups include very young, elderly, transplant recipient, and immunocompromised individuals. HCMV may cause retinitis, encephalitis, hepatitis, esophagitis, colitis, pneumonia, neonatal infection sequelae, inflammatory, and age-related diseases. With an arsenal of genes in its large genome dedicated to host immune evasion, HCMV can block intrinsic cellular defenses and interfere with cellular immune responses. HCMV also encodes chemokines, chemokine receptors, and cytokines. Therefore, genes involved in human viral defense mechanisms and those encoding proteins targeted by the CMV proteins are candidates for host control of CMV infection and reactivation. Although still few in number, host genetic studies are producing valuable insights into biological processes involved in HCMV pathogenesis and HCMV-related diseases. For example, genetic variants in the immunoglobulin GM light chain can influence the antibody responsiveness to CMV glycoprotein B and modify risk of HCMV-related diseases. Moreover, CMV infection following organ transplantation has been associated with variants in genes encoding toll-like receptors (TLRs), programmed death-1 (PD-1), and interleukin-12p40 (IL-12B). A KIR haplotype (2DS4+) is proposed to be protective for CMV activation among hematopoietic stem cell transplant patients. Polymorphisms in the interferon lambda 3/4 (IFNL3/4) region are shown to influence susceptibility to CMV replication among solid organ transplant patients. Interestingly, the IFNL3/4 region is also associated with AIDS-related CMV retinitis susceptibility in HIV-infected patients. Likewise, interleukin-10 receptor 1 (IL-10R1) variants are shown to influence CMV retinitis development in patients with AIDS. Results from genome-wide association studies suggest a possible role for microtubule network and retinol metabolism in anti-CMV antibody response. Nevertheless, further genetic epidemiological studies with large cohorts, functional studies on the numerous HCMV genes, and immune response to chronic and latent states of infection that contribute to HCMV persistence are clearly necessary to elucidate the genetic mechanisms of CMV infection, reactivation, and pathogenesis.

The human cytomegalovirus glycoprotein pUL11 acts via CD45 to induce T cell IL-10 secretion

Human Cytomegalovirus (HCMV) is a widespread pathogen, infection with which can cause severe disease for immunocompromised individuals. The complex changes wrought on the host's immune system during both productive and latent HCMV infection are well known. Infected cells are masked and manipulated and uninfected immune cells are also affected; peripheral blood mononuclear cell (PBMC) proliferation is reduced and cytokine profiles altered. Levels increase of the anti-inflammatory cytokine IL-10, which may be important for the establishment of HCMV infections and is required for the development of high viral titres by murine cytomegalovirus. The mechanisms by which HCMV affects T cell IL-10 secretion are not understood. We show here that treatment of PBMC with purified pUL11 induces IL-10 producing T cells as a result of pUL11 binding to the CD45 phosphatase on T cells. IL-10 production induced by HCMV infection is also in part mediated by pUL11. Supernatants from pUL11 treated cells have anti-inflammatory effects on untreated PBMC. Considering the mechanism, CD45 can be a positive or negative regulator of TCR signalling, depending on its expression level, and we show that pUL11 also has concentration dependent activating or inhibitory effects on T cell proliferation and on the kinase function of the CD45 substrate Lck. pUL11 is therefore the first example of a viral protein that can target CD45 to induce T cells with anti-inflammatory properties. It is also the first HCMV protein shown to induce T cell IL-10 secretion. Understanding the mechanisms by which pUL11-induced changes in signal strength influence T cell development and function may provide the basis for the development of novel antiviral treatments and therapies against immune pathologies.

Can immune-related genotypes illuminate the immunopathogenesis of cytomegalovirus disease in human immunodeficiency virus-infected patients?

Most human immunodeficiency virus (HIV) patients are seropositive for cytomegalovirus (CMV) but a smaller proportion experience end-organ disease. This observation may reflect variations in genes affecting inflammatory and natural killer cell responses. DNA samples were collected from 240 HIV-infected patients followed at the University Hospitals/Case Medical Center (Cleveland, OH) between 1993 and 2008. Seventy-eight patients (African Americans = 41, Caucasians = 37) experienced CMV disease. Genotypes were determined using allele-specific fluorescent probes or multiplex polymerase chain reaction sequence-specific primers. IL12B3'UTR*(1) and SLC11A1 D543N*(1,2) were associated with CMV disease in African American patients (p = 0.04 and p = 0.02, respectively). IL10-1082*(1,2) and LILRB1 I142T*(1) were associated with CMV disease in Caucasians (p = 0.02 and p = 0.07, respectively). DARC T-46C*(1) and CD14 C-159T*(2) were associated with low nadir CD4(+) T cell counts in African American patients (p = 0.002 and p = 0.01, respectively). Caucasian patients carrying TNFA-308*2, TNFA-1031*(2), IL2-330*(1), CCL2-2518*(2), or LILRB1 I142T*(1) had significantly lower nadir CD4(+) T cells in a bootstrapped multivariable model (p = 0.006-0.02). In general, polymorphisms associated with CMV disease and CD4(+) T cell counts were distinct in Caucasian and African American patients in the United States. The LILRB1 I142T polymorphism was associated with both CMV disease and low nadir CD4(+) T cell counts in Caucasians, but the clearest determinant of low nadir CD4(+) T cell count in African American patients was DARC T-46C.

Primary response against cytomegalovirus during antiviral prophylaxis with valganciclovir, in solid organ transplant recipients

Antiviral prophylaxis has proved successful for prevention of cytomegalovirus (CMV) disease in solid organ transplant (SOT) patients; though emerging data suggest that antiviral agents interfere with immunity, and may inhibit immune priming. In this context, we investigated levels and phenotype of primary CMV-specific immune responses that developed during antiviral prophylaxis in a cohort of CMV seronegative recipients (R(-) ) of a SOT from a seropositive donor (D(+) ). We longitudinally monitored CMV viral load, antibodies and levels of the negative immuno-modulator IL-10. PBMC were stimulated with CMV-specific peptide libraries to measure CD137 activation marker on CMV-specific T-cells and levels of PD-1 receptor, which is over expressed on exhausted T-cells. Unexpectedly, the majority (13/18) of D(+) R(-) patients who developed a primary CMV response showed early post-transplant CMV-specific responses, though levels of PD-1 on CMV-specific T-cells remained elevated throughout prophylaxis. A strong inverse association was found between levels of plasma IL-10 and CMV-specific cellular immune responses. Our study suggests that during prophylaxis, subclinical CMV infection might have occurred in the D(+) R(-) patients, and primary CMV-specific responses were detected early post-transplant when levels of plasma IL-10 were low. Extended prophylaxis or antiviral treatment did not appear to suppress CMV-specific antibodies or T-cells, which, however, showed exhaustion phenotypes.

Interleukin-10 repletion suppresses pro-inflammatory cytokines and decreases liver pathology without altering viral replication in murine cytomegalovirus (MCMV)-infected IL-10 knockout mice

Objective and design

To determine the role of interleukin-10 (IL-10) in protecting against the deleterious pro-inflammatory cytokine response to murine cytomegalovirus (MCMV), we studied the impact of IL-10 repletion in MCMV-infected IL-10 knockout (KO) mice.

Materials and methods

IL-10 KO mice were infected with a sub-lethal dose of MCMV and treated daily with 5 μg of mouse recombinant IL-10 (mrIL-10). Cytokine transcription, viral load, cytokine expression and liver histopathology were assessed in IL-10 treated and untreated mice.

Results

mrIL-10 repletion suppressed the exaggerated pro-inflammatory cytokine response observed in IL-10 KO mice (vs. control) both systemically and at the organ level, without affecting viral load. Levels of IFN-γ and TNF-α mRNA in livers of treated mice were ~50–70-fold lower than in untreated mice at day 5 post-infection (p ≤ 0.05). In spleens and sera, levels of IFN-γ and IL-6 were significantly lower in treated mice than in untreated mice at day 5–7 post-infection (p ≤ 0.05). IL-10 blunting of cytokine responses was accompanied by attenuation of inflammation in livers of treated mice.

Conclusions

Repletion of IL-10 modulates the exaggerated pro-inflammatory cytokine responses that characterize IL-10 KO mice and protects against liver damage without altering viral load. IL-10 may be useful to control dysregulated pro-inflammatory cytokines responses during CMV infection.

Association between a polymorphism in the IL-12p40 gene and cytomegalovirus reactivation after kidney transplantation

BACKGROUND

Cytomegalovirus (CMV) infection is associated with a significant rate of morbidity after organ transplantation. The genetic factors influencing its occurrence have been little investigated. IL-12 plays a crucial role in anti-infectious immune responses, especially by stimulating IFNgamma production. An A-to-C single nucleotide polymorphism (SNP) within the 3'-untranslated region of the IL-12p40 gene has been characterized and was reported to be both functionally and clinically relevant. However, the impact of this single nucleotide polymorphism on events after organ transplantation has never been reported.

METHODS

In this study, we investigated the impact of the 3'-untranslated region polymorphism on the occurrence of CMV infection in 469 kidney recipients transplanted at the University Hospital of Tours between 1995 and 2005. The polymorphism was genotyped using the restriction fragment length polymorphism method and CMV infection was determined by pp65 antigenemia.

RESULTS

Multifactorial Cox regression analysis demonstrated that the presence of the C allele was an independent risk factor for CMV infection (OR=1.52, P=0.043), the risk being even higher when study was restricted to patients with positive CMV serological status before the graft and who did not receive any CMV prophylaxis (OR=1.88, P=0.028).

CONCLUSIONS

This study identified a new genetic risk factor for CMV reactivation after kidney transplantation. The results of our study suggest that C carriers might especially benefit from CMV prophylaxis.

Interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) levels and IL-6, TNF-polymorphisms in children with thrombosis

Infection has an important role in the pathogenesis of thrombosis and it becomes more prominent in childhood cases, in whom the infection frequency is higher. It has been suggested that patients with high tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 levels might be at increased risk of developing thrombotic complications owing to the effects of these cytokines on the coagulation pathway. Functional polymorphisms in the promoter regions of the genes coding for TNF-alpha and IL-6 are associated with increased plasma levels of these cytokines. The aims of this study were to evaluate the serum levels of acute phase reactants, such as C-reactive protein, and of cytokines (TNF-alpha and IL-6) and to investigate the association between the TNF-alpha-308 G/A and IL-6-174 G/C polymorphisms in Turkish pediatric patients with thrombosis. Fifty-eight children with thrombosis (group 1) and 89 controls (group 2) were included in the study. Patients who had a history of infection within the 15 days before thrombosis were classified as group 1a and those who had no infection history before thrombosis were classified as group 1b. Serum TNF-alpha did not differ significantly between the groups. However, the IL-6 level was higher in group 1a than in group 1b (P<0.05). The genotype distribution and allele frequencies of TNF-alpha G/A polymorphism were significantly higher in the thrombotic children without infection and in the control group than in the thrombotic children with an infection history (P<0.05). The IL-6-174 C/C genotype was significantly higher in thrombotic children with an infection history (P<0.05); there were no differences between the groups in mean allele frequency (Table 2). On the basis of our results, patients with a history of infection seem to have higher C-reactive protein and IL-6 levels and IL-6-174 C/C genotype. Furthermore, venous thrombosis is more frequent in this group than arterial thrombosis (P<0.05).

Autosomal dominant polycystic kidney disease is not a risk factor for post-transplant diabetes mellitus. Matched-pair design multicenter study

BACKGROUND

Post-transplant diabetes mellitus (PTDM) is a relatively common complication of kidney transplantation. The aim of our work was to compare the incidence of PTDM in kidney transplant recipients with and without autosomal dominant polycystic kidney disease (ADPKD) in a matched-pair design study.

METHODS

In total, 98 pairs of graft recipients, all of Caucasian origin and who received a kidney from the same cadaveric donor, were included in the study. The following clinical data were collected for statistical analysis: age, body mass index (BMI) before transplant, length and type of dialysis treatment, residual diuresis, and cold and warm graft ischemia time. Diabetes was diagnosed based on American Diabetes Association (ADA) criteria.

RESULTS

Incidence of PTDM was 19.4% in the ADPKD group and 18.4% in the non-ADPKD group, with no significant differences between groups. Multivariate logistic regression analysis of the PTDM risk in the ADPKD group including age, gender, BMI, and dialysis time as independent variables indicated that only higher residual diuresis is a significant independent risk factor (OR = 5.64 per every L/24 h, 95% CI = 1.31-24.33, p = 0.017). Similarly, logistic regression analysis adjusted for age and gender in the non-ADPKD group has shown that significant independent risk factors are BMI (OR = 1.30 per every kg/m(2), 95% CI = 1.06-1.59, p = 0.0094), longer dialysis time prior to transplant (OR = 1.036 per each month, 95% CI = 1.004-1.070, p = 0.025), and a history of arterial hypertension (OR = 9.09, 95% CI = 1.20-68.66, p = 0.030).

CONCLUSIONS

In this paired analysis, our results suggest that diagnosis of ADPKD does not increase risk of PTDM.

Cytokine Polymorphisms and Risk of Infection After Kidney Transplantation

INTRODUCTION

Infection remains a significant cause of morbidity and mortality after solid organ transplantation. Genetic background has an influence on the incidence of infection. The aim of our study was to analyze the relationship between cytokine polymorphisms and infection in our kidney transplant recipients.

METHODS

DNA from 255 kidney transplant recipients was isolated routinely. Polymerase chain reaction sequence-specific primer was performed using commercially available cytokine genotyping primer packs to determine polymorphisms of interleukin (IL)-10, transforming growth factor-beta, tumor necrosis factor-alpha, interferon-gamma, IL-6, IL-4, IL-2, IL-12, IL-4R alpha, IL-1RA, IL-1R, IL-1 beta, and IL-1 alpha. The appearance and number of infections within the first year after transplantation were identified retrospectively.

RESULTS

One hundred twenty-two patients experienced at least one episode of infection in the first year after transplant. The frequency of the -511 IL-1beta CC genotype and the frequencies of the -1188 IL-12 CA and CC genotypes were significantly higher among the infected patients compared with the noninfected patients. We failed to observe significant differences in the genotype distribution of the other analyzed cytokines regarding the incidence of infection. After adjusting, recipient IL-1beta (-511 CC) genotype (relative risk [RR] 2.67, 95% confidence interval (CI) 1.30 to 5.49, P = .007) and recipient IL-12 (-1188 CA and CC) genotypes (RR 2.57, 95% CI 1.22 to 5.38, P = .012) predicted independently the risk of infection in the first year after kidney transplantation.

CONCLUSION

Kidney transplant recipients with -511 IL-1beta CC genotype or with -1188 IL-12 CA and CC genotypes were at higher risk of developing infections in the first year after transplantation. Patients with genetic susceptibility to infection may benefit from less potent immunosuppressive therapy and more intense preventive measures.