Litjens, N.H.R.

Systemic varicella zoster virus reactive effector memory T-cells impaired in the elderly and in kidney transplant recipients (Article)

2012-12-01T00:00:00Z

Varicella zoster virus (VZV) infections cause varicella and subsequently herpes zoster upon reactivation. Immune-compromised individuals and the elderly are at high risk of developing herpes zoster due to waning of VZV-specific T-cell immunity. In the present study, a novel functional T-cell assay was developed to test the correlation between age and VZV-specific T-cell responses in peripheral blood from healthy individuals. Secondly, VZV-specific T-cell responses from renal transplant recipients were compared with healthy individuals. Monocytes were differentiated into mature monocyte-derived dendritic cells (moDCs) and were infected with VZV. T-cells were co-cultured with autologous moDCs infected with VZV and subjected to flowcytometric analysis to identify the phenotype (i.e., naïve [NA: CCR7+CD45RO-], central [CM: CCR7+CD45RO+] and effector memory [EM: CCR7-CD45RO+] T-cells) and the frequency of VZV-reactive T-cell subsets by intra-cellular IFN-γ flowcytometry. In contrast to NA and CM T-cells, the frequency of VZV-reactive CD4 and CD8 EM T-cells was inversely correlated with age (P=0.0007 and P=0.01). No difference was found in the percentage of VZV-reactive CD4 NA, CM and EM T-cells between transplant recipients and controls. However, the percentage of VZV-reactive CD8 EM T-cells was significantly lower in transplant recipients compared to controls (P=0.02). In conclusion, moDCs infected with VZV are efficient antigen presenting cells applicable to enumerate and characterize the phenotype and differentiation status of the systemic VZV-specific T-cell response ex-vivo. The data suggest that VZV-reactive EM T-cells are impaired in the elderly and renal transplant recipients.

Premature aging of circulating T cells in patients with end-stage renal disease (Article)

2011-07-02T00:00:00Z

Progressive loss of renal function is associated with a dysregulation of circulating T cells that may underlie their impaired T-cell immunity. Here we tested whether end-stage renal disease (ESRD)-related T-cell alterations are compatible with the concept of premature immunological aging. Younger patients (25-45 years old) with ESRD were found to resemble older healthy controls (60-80 years old) as they had a significant loss of naive T cells and a relative increase of memory T cells showing progressive terminal differentiation. A significant decrease in the content of T-cell receptor excision circles and telomere length in patients with ESRD confirmed these phenotypic data. The loss of naive T cells in patients with ESRD was associated with an excessive age-related decrease of recent thymic emigrants, indicating a premature decline in thymic function. Additionally, increased homeostatic proliferation of naive T cells was found in patients with ESRD, similar to that of older healthy individuals, with an increased susceptibility for activation-induced apoptosis. Therefore, both decreased thymic output and increased susceptibility of naive T cells for apoptosis may play a role in the loss of naive T cells in ESRD patients. Thus, our results are compatible with premature aging of the T-cell system of patients with ESRD comparable with that of healthy individuals 20-30 years older.

Differential effects of age, cytomegalovirus-seropositivity and end-stage renal disease (ESRD) on circulating T lymphocyte subsets (Article)

2011-01-08T00:00:00Z

The age- and cytomegalovirus (CMV)-seropositivity-related changes in subsets and differentiation of circulating T cells were investigated in end-stage renal disease (ESRD) patients (n = 139) and age-matched healthy individuals. The results show that CMV-seropositivity is associated with expansion of both CD4+and CD8+memory T cells which is already observed in young healthy individuals. In addition, CMV-seropositive healthy individuals have a more differentiated memory T cell profile. Only CMV-seropositive healthy individuals showed an age-dependent decrease in CD4+näve T cells. The age-related decrease in the number of CD8+näve T cells was CMV-independent. In contrast, all ESRD patients showed a profound näve T-cell lymphopenia at every decade. CMV-seropositivity aggravated the contraction of CD4+näve T cells and increased the number of differentiated CD4+and CD8+memory T cells. In conclusion, CMV-seropositivity markedly alters the homeostasis of circulating T cells in healthy individuals and aggravates the T cell dysregulation observed in ESRD patients.

CMV seropositivity determines epoetin dose and hemoglobin levels in patients with CKD (Article)

2009-12-01T00:00:00Z

Cytomegalovirus (CMV)-seropositive patients with ESRD may have more CD4+T cells lacking the co-stimulatory molecule CD28 (CD4+CD28null) than CMV-seronegative patients. Increased numbers of CD28null T cells associates with epoetin nonresponsiveness in patients with ESRD, but whether expansion of CD4+CD28null T cells in CMV-seropositive patients associates with demand for epoetin is unknown. In a cohort of 129 stable patients with ESRD, CMV seropositivity significantly associated with a lower hemoglobin level in predialysis patients (12.5 versus 11.5 g/dl; P < 0.02). CMV seropositivity did not associate with average hemoglobin level in hemodialysis patients, but CMV-seropositive patients required significantly more epoetin (median 12,000 versus 6300 U/wk; P = 0.02). Multivariate linear regression analysis identified CMV seropositivity as the only variable significantly associated with hemoglobin levels in predialysis patients and epoetin dosages in hemodialysis patients. In CMV-seropositive hemodialysis patients, the number of circulating CD4+CD28null T cells positively correlated with epoetin dosage. These CD4+CD28null T cells were proinflammatory; they were capable of producing large amounts of IFN-γ and TNF-α. In conclusion, expansion of CD4+CD28null T cells in CMV-seropositive patients with ESRD associates with increased demand for epoetin. Copyright

The human alloreactive CD4+ T-cell repertoire is biased to a Th17 response and the frequency is inversely related to the number of HLA class II mismatches (Article)

2009-10-29T00:00:00Z

Estimates of precursor frequency and assessment of functional characteristics of alloreactive CD4+T cells are all biased by the need for long-term culture. In this study, direct visualization of human alloreactive CD4+T cells on the single-cell level was achieved using cell surface expression of CD154 as a tool for identification. The average frequency of alloreactive CD154+CD4+T cells among peripheral blood CD4+T cells was 0.1%, with half of the cells displaying a naive phenotype. The proliferation capacity and expression of cytokines after allogeneic stimulation resided in these CD154+CD4+T cells. The repertoire of alloreactive CD4+T cells was biased to a Th17 response, and on average 24% of alloreactive CD154+CD4+memory T cells produced interleukin-17 (IL-17) after polyclonal stimulation. Unexpectedly, mixed cell cultures from human leukocyte antigen (HLA)-identical donors also generated alloreactive CD154+CD4+T cells and yielded the highest frequency compared with HLA-nonidentical combinations. Therefore, reactivity to minor histocompatibility antigens between HLA-identical subjects appears to be relatively common. Alloreactive HLA-identical T cells did not proliferate or express cytokines, but were driven to proliferation in the presence of exogenous IL-2.

Expansion of cytolytic CD4+CD28- T cells in end-stage renal disease (Article)

2008-09-01T00:00:00Z

Cytomegalovirus (CMV) seropositivity is associated with increased risk for atherosclerotic disease in patients with end-stage renal disease. This association is due to a unique peripheral blood CD4+T cell population which lack CD28 (CD4+CD28-T cells). Here we found that this patient population has a significant age-dependent increase of CD4+CD28-T cells that comprise over half of the circulating CD4 T cells in some. Patients over 50 years of age have a 50-fold higher percentage of CD4+CD28-T cells compared to seronegative patients and a 5-fold higher percentage when compared to seropositive healthy controls. Stimulation by CMV-antigen or by polyclonal stimulation using PMA and ionomycin showed that CD4+CD28-cells in patients with end stage renal disease degranulated and secreted interferon γ thus indicating that they are cytolytic. The average anti-CMV IgG titer displayed a remarkable age-dependent increase only in patients with end stage renal disease. These findings are highly suggestive of repetitive antigenic stimulation of the immune system in patients with end stage disease by subclinical CMV reactivation which might contribute to increased atherosclerotic risk.

Impaired immune responses and antigen-specific memory CD4+ T cells in hemodialysis patients (Article)

2008-08-01T00:00:00Z

Serologic responses to T cell-dependent vaccinations are severely attenuated in patients with ESRD, but the reasons for this is unknown. In this study, a detailed analysis of antigen-specific T cell responses was performed. Patients on hemodialysis and age- and gender-matched healthy control subjects were vaccinated with hepatitis B surface antigen (HBsAg), antigen-specific CD4+T cells were monitored at regular intervals with intracellular cytokine staining and proliferation assays. IL-2- and IFN-γ-producing CD4+T cells were identified as either central or effector memory CD4+T cells using antibodies directed against CD45RO and the chemokine receptor CCR7. Control subjects mounted a memory T cell response comprising both central and effector memory CD4+T cells, with the central memory response occurring 1 wk before the effector memory response. IL-2+HBsAg-specific memory CD4+T cells were primarily detected within the effector population. Patients with ESRD showed a delayed response of IL-2- and IFN-γ-producing central memory CD4+T cells, but their maximal responses were similar to those of control subjects. In contrast, patients with ESRD produced only 6.3% of the IL-2+HBsAgspecific effector memory CD4+T cells produced by control subjects (0.5 ± 0.2 × 104/L versus 8 ± 3.5 × 104/L; P < 0.001), and this impaired response correlated with antigen-specific T cell proliferation and anti-HBsAg IgG titers. In conclusion, the production of antigen-specific effector memory CD4+T cells after vaccination, which is critical to achieve an adequate humoral response, is severely impaired in patients with ESRD. Copyright

Hepatitis B vaccine-specific CD4+ T cells can be detected and characterised at the single cell level: Limited usefulness of dendritic cells as signal enhancers (Article)

2008-01-31T00:00:00Z

Hepatitis B surface antigen (HBsAg)-specific T cells were analysed in 16 healthy individuals vaccinated against hepatitis B, using optimised protocols. HBsAg-specific IFN-γ producing CD4+T cells were found at a similar low frequency (0.01%) within the naive T cell subset, the central and the effector memory T cell subset. Overall, HBsAg-specific total CD4+T cells were detected in approximately 81% of the HBV vaccinees. The use of dendritic cells substantially increased the otherwise low proliferative responses but not the percentage of IFN-γ producing cells. The analysis of readily detectable CMV-specific CD4+T cell responses was used as a positive control and confirmed the adequacy of our assays. T cell responses associated with (in-) adequate hepatitis B vaccination can now be analysed in more detail.

Seropositivity for cytomegalovirus in patients with end-stage renal disease is strongly associated with atherosclerotic disease (Article)

2007-11-01T00:00:00Z

Background. Infection with cytomegalovirus (CMV) is considered a risk factor for progression of atherosclerotic disease. Patients with end-stage renal disease (ESRD) display signs of frequent CMV re-activation, which may be caused by the uraemia-associated defect in cellular immunity. The possible contribution of CMV seropositivity to the hugely increased risk for cardiovascular disease in patients with ESRD is not clear. Methods. In a retrospective study we analysed the clinical data of patients with ESRD that were evaluated for renal transplantation from January 2002 to March 2006. Classical cardiovascular risk factors and CMV seropositivity were related to the prevalence of atherosclerotic disease. Results. A total of 408 patients were evaluated with a median age of 52 years (range 18-81 years). Multivariate logistic regression identified age (odds ratio; OR 2.7 per decade), smoking (OR 2.2), hypertension (OR 1.9), C-reactive protein (CRP) (OR 2.6) and CMV seropositivity (OR 2.7) as independent variables that were significantly associated with a positive medical history of atherosclerotic disease. The average titre for anti-CMV immunoglobulin G was higher in patients with atherosclerotic disease (100 AU/ml vs 71 AU/ml, P < 0.05). CMV seropositivity was independently associated with an elevated CRP. In addition, patients with the combination of a high CRP and CMV seropositivity showed the highest prevalence of atherosclerotic disease. Conclusion. CMV seropositivity is significantly associated with atherosclerotic disease in ESRD patients. Our data suggest that the risk for progressive atherosclerosis is specifically increased in patients with an inflammatory response to CMV.