Association of high IFN-gamma plasma levels with low B-cell counts in renal transplant recipients with stable long-term graft function

Acute Versus Chronic Administration of Calcineurin-Inhibitors Differentially Affect T-Cell Function

BACKGROUND

Calcineurin-inhibitors (CNI) are used in renal transplant patients (RTX) to prevent rejection. CNI mainly suppress T-cell mediated immunity but very little is known about the impact of long-term treatment with CNI on T-cell function.

OBJECTIVE

We investigated the immunological effects of long-term CNI intake in RTX patients in comparison to short-term CNI administration in healthy controls (HC).

METHODS

Blood was drawn from 30 RTX patients with long-term CNI treatment. In addition, blood was sampled from HC with short-term CNI treatment (four dosages) before the first and 2 hours after the last CsA intake. T-cells were analyzed for cytokine production, proliferation, and CD25 expression.

RESULTS

Short-term CNI reduced T-cell derived IL-2 and IFNγ as well as T-cell proliferation in HC. IFNγ was not suppressed in patients with long-term CNI treatment. IL-2 production, CD25 expression, and T-cell proliferation were enhanced in long-term CNI patients.

CONCLUSION

Suppression of IFNγ/IL-2 and T-cell proliferation is weaker during long-term CNI treatment in patients compared to short-term treatment in healthy subjects. Enhanced CD25 expression may lower the threshold for T-cell activation during long-term CNI treatment.

Lack of Association Between Elevated Urinary Levels of Interleukin-10 and Interferon Gamma With the Presence of Inflammation in Kidney Transplant Recipients

INTRODUCTION

A lot of evidence has demonstrated the importance of different cytokines in acute renal rejection. Previous studies have examined the presence or absence of interleukin (IL)-10 in related immunopathologic rejection grafts as well as other interleukins. Studies in human transplantation show elevated levels of IL-10 and gamma interferon (INF-γ) in inflammation and rejection.

OBJECTIVE

The objective of this study was to demonstrate the lack of association of elevated urinary levels of IL-10 and IFN in the presence of active inflammation.

METHODS

An observational, descriptive, cross-sectional study conducted in transplant recipients at 12 months of follow-up after renal transplantation. In those who were held biopsy after renal transplantation at one year follow-up, or allograft dysfunction, we also measured IL-10 and INF-γ in the urine. The following were considered as variables: age, body mass index (BMI), gender, transplant type, creatinine, chronic kidney disease epidemiology collaboration equation, (CKD-EPI), modification of diet in renal disease study equation (MDRD), Banff classification, and levels of IL-10 and INF-γ. Statistical analysis was performed calculating a sample size of 25 patients, with an alpha bias of 0.05%, yielding measures of central tendency and determining no association between levels of IL-10 and INF-γ with the presence of rejection using SPSS 21.0 program.

RESULTS

A total of 50 patients, 34 (68%) males, 16 (32%) females, with an average 31.7 ± 9.9 years, weight of 64.91 ± 13.84 kg, size 1.60 ± 0.10 m and 24.97 ± 4.07 BMI were included,39 (78%) living donor and 11 (22%) cadaveric. Twenty-six (52%) showed inflammation in the biopsy and 24 (48%) showed none. Mean creatinine was 1.81 ± 1.5, and the estimated glomerular filtration rate (eGFR) was 55.27 ± 22.46, 65.76 ± 26.7. (MDRD and CKD-EPI, respectively). No statistical difference was found in the levels of IL-10 and IFN-γ using analysis of variance. (ANOVA; P = .467 and P = .063, respectively) Based on Banff, the inflammation on biopsy score was 2.78 ± 2.84. There was statistical significance (P < .05) with respect to the Cr and eGFR by different equations. There were no significant interactions between cytokine levels and more than 1 factor. (as indicated by P < .2).

DISCUSSION AND CONCLUSIONS

No significant differences were observed in the level of interleukins in patients with and without inflammation, denoting an adequate immunosuppression in most of these patients. Determination of inflammatory cytokines in urine could be used as a determinant of a good immunosuppression status, rather than as an early marker of rejection.

Circulating lymphocyte subsets in different clinical situations after renal transplantation

Phenotypic characterization of T and B lymphocytes allows the discrimination of functionally different subsets. Here, we questioned whether changes in peripheral lymphocyte subset distribution reflect specific clinical and histopathological entities after renal transplantation. Sixty-five renal transplant recipients with either histologically proven (sub)clinical acute rejection or chronic allograft dysfunction, or without abnormalities were studied for their peripheral lymphocyte subset composition and compared with 15 healthy control individuals. Naive, memory and effector CD8(+) T-cell counts were measured by staining for CD27, CD28 and CD45RO/RA. In addition, we studied the CD25(+) CD4(+) T-cell population for its composition regarding regulatory Foxp3(+) CD45RO(+) CD127(-) cells and activated CD45RO(+) CD127(+) cells. Naive, non-switched and switched memory B cells were defined by staining for IgD and CD27. We found a severe decrease in circulating effector-type CD8(+) T cells in recipients with chronic allograft dysfunction at 5 years after transplantation. Percentages of circulating CD25(+) CD127(low) CD4(+) regulatory T cells after transplantation were reduced, but we could not detect any change in the percentage of CD127(+) CD45RO(+) CD4(+) activated T cells in patients at any time or condition after renal transplantation. Regardless of clinical events, all renal transplant recipients showed decreased total B-cell counts and a more differentiated circulating B-cell pool than healthy individuals. The changes in lymphocyte subset distribution probably reflect the chronic antigenic stimulation that occurs in these transplant recipients. To determine the usefulness of lymphocyte subset-typing in clinical practice, large cohort studies are necessary.

Transplant long-surviving induced by CD40-CD40 ligand costimulation blockade is dependent on IFN-γ through its effect on CD4(+)CD25(+) regulatory T cells

BACKGROUND

IFN-γ was documented to be commonly associated with acute rejection. In the present study, we investigated the role of IFN-γ in the transplant long-surviving induced by blocking CD40-CD40 ligand (CD40-CD40L) costimulation and its mechanisms.

METHODS

IFN-γ expression in cardiac allografts and spleens from syngeneic and allogeneic recipients with or without anti-CD40L monoclonal antibody (MR-1) treatment was examined by real-time RT-PCR. The grafts survival time in Wild type (IFN-γ(+/+)) and IFN-γ deficient (IFN-γ(-/-)) recipients was investigated. Mixed lymphocyte reaction (MLR) of CD4(+) T cells and cytotoxic T lymphocyte (CTL) assay of CD8(+) T cells were also studied. FoxP3 expression in allografts and spleens from IFN-γ(+/+) or IFN-γ(-/-) recipients with MR-1 treatment was examined. Furthermore, FoxP3, IL-10 and CTLA-4 expressions and the suppressive capability of CD4(+)CD25(+) regulatory T cells were examined.

RESULTS

Rejected allografts showed significantly higher IFN-γ expression than long-surviving allografts. Allograft survival was not prolonged in nonimmunosuppressed IFN-γ(-/-) mice. Administration of MR-1 induced long-term survival in 90.1% of IFN-γ(+/+) recipients (98±6.6 days) but failed to do so in IFN-γ(-/-) group (16.2±4.0 days). IFN-γ(-/-) recipients facilitated the proliferation and CTL generation of T cells. The allografts and spleens from IFN-γ(+/+) recipients contained higher FoxP3 expression than IFN-γ(-/-) recipients. Moreover, CD4(+)CD25(+) T cells from IFN-γ(+/+) recipients displayed a higher FoxP3 and IL-10 expression and suppressive capability.

CONCLUSION

IFN-γ plays an important role in the long-surviving induced by blocking CD40-CD40L through inhibiting the function of activated T cells and increasing suppressive capability of CD4(+)CD25(+) regulatory T cells.