The Burden of Gastrointestinal Complaints in Kidney Transplant Recipients Using Tacrolimus With and Without Mycophenolate Mofetil: A Randomized Controlled Study.

Background: Tacrolimus (TAC) combined with mycophenolate mofetil (MMF) is the immunosuppressive regimen in the majority of solid organ transplant recipients. Gastrointestinal complaints are frequent, which is considered predominantly a side effect of MMF. However, systematic research in this field is lacking. The aim of this study is to systematically investigate the burden of gastrointestinal complaints in TAC-treated kidney transplant recipients with and without MMF. Methods: In a single-center, open-label, randomized controlled trial, low immunological risk recipients were randomized to either TAC and MMF or to TAC monotherapy from 6 months after kidney transplantation onwards [NTR4672],. They filled in the Gastrointestinal Symptom Rating Scale questionnaire, which covers five dimensions (abdominal pain, reflux, indigestion, constipation, and diarrhea), 6, 12, and 15 months after transplantation. Results: Seventy-nine recipients were randomized and 72 completed all questionnaires (34 TACmono and 38 TAC/MMF). At baseline, the mean age was 59 years with 72% male, mean BMI 28 kg/m2, eGFR 55 ml/min/1.73m2, mean daily dose MMF 1200 mg and TAC 5.8 mg, with trough levels of 2.1 mg/L and 7.4 ug/L. Six months after transplantation, 75% of recipients reported troublesome symptoms (score ≥3). Diarrhea was the most troublesome (mean 3.3) and discontinuing MMF significantly reduced it (mean Δ score between month 6 and 15 TAC/MMF -0.9 vs. TACmono -1.8, p=0.03). In recipients with troublesome symptoms, abdominal pain (2.7 to 1.8, p=0.003), indigestion (2.8 to 2.3, p=0.012), and reflux (2.9 to 1.7, p=0.007) significantly decreased over time, independent of MMF use. Conclusion: The majority of kidney transplant recipients with TAC and MMF experienced troublesome gastrointestinal symptoms 6 months after transplantation. While constipation remained troublesome, indigestion, abdominal pain, and reflux improved over time by month 15. Diarrhea only improved after discontinuing MMF.

Uremia-Associated Ageing of the Thymus and Adaptive Immune Responses.

Progressive loss of renal function is associated with a series of changes of the adaptive immune system which collectively constitute premature immunological ageing. This phenomenon contributes significantly to the mortality and morbidity of end-stage renal disease (ESRD) patients. In this review, the effect of ESRD on the T cell part of the adaptive immune system is highlighted. Naïve T cell lymphopenia, in combination with the expansion of highly differentiated memory T cells, are the hallmarks of immunological ageing. The decreased production of newly formed T cells by the thymus is critically involved. This affects both the CD4 and CD8 T cell compartment and may contribute to the expansion of memory T cells. The expanding populations of memory T cells have a pro-inflammatory phenotype, add to low-grade inflammation already present in ESRD patients and destabilize atherosclerotic plaques. The effect of loss of renal function on the thymus is not reversed after restoring renal function by kidney transplantation and constitutes a long-term mortality risk factor. Promising results from animal experiments have shown that rejuvenation of the thymus is a possibility, although not yet applicable in humans.

T-cell ageing in end-stage renal disease patients: Assessment and clinical relevance.

End-stage renal disease (ESRD) patients have a defective T-cell-mediated immune system which is related to excessive premature ageing of the T-cell compartment. This is likely to be caused by the uremia-associated pro-inflammatory milieu, created by loss of renal function. Therefore, ESRD patients are highly susceptible for infections, have an increased risk for virus-associated cancers, respond poorly to vaccination and have an increased risk for atherosclerotic diseases. Three ageing parameters can be used to assess an immunological T-cell age. First, thymic output can be determined by assessing the T-cell receptor excision circles-content together with CD31 expression within the naïve T cells. Second, the telomere length of T cells and third the T-cell differentiation status are also indicators of T-cell ageing. Analyses based on these parameters in ESRD patients revealed that the immunological T-cell age is increased by on average 20 years compared to the chronological age. After kidney transplantation (KTx) the aged T-cell phenotype persists although the pro-inflammatory milieu is diminished. This might be explained by epigenetic modifications at hematopoietic stem cells level. Assessment of an immunological T-cell age could be an important tool to identify KTx recipients who are at risk for allograft rejection or to prevent over-immunosuppression.

Human Bone Marrow- and Adipose Tissue-derived Mesenchymal Stromal Cells are Immunosuppressive In vitro and in a Humanized Allograft Rejection Model.

BACKGROUND: Recent studies with bone marrow (BM)-derived Mesenchymal Stromal Cells (MSC) in transplant recipients demonstrate that treatment with MSC is safe and clinically feasible. While BM is currently the preferred source of MSC, adipose tissue is emerging as an alternative. To develop efficient therapies, there is a need for preclinical efficacy studies in transplantation. We used a unique humanized transplantation model to study the in vivo immunosuppressive effect of human BM-MSC and adipose tissue-derived MSC (ASC). METHODS: Gene expression of BM-MSC and ASC and their capacity to inhibit activated PBMC proliferation was evaluated. The in vivo immunosuppressive effect of BM-MSC and ASC was studied in a humanized mouse model. SCID mice were transplanted with human skin grafts and injected with human allogeneic PBMC with or without administration of BM-MSC or ASC. The effect of MSC on skin graft rejection was studied by immunohistochemistry and PCR. RESULTS: BM-MSC and ASC expressed TGFß, CXCL-10 and IDO. IDO expression and acitivity increased significantly in BM-MSC and ASC upon IFN-γ stimulation. IFN-γ stimulated BM-MSC and ASC inhibited the proliferation of activated PBMC in a significant and dose dependent manner. In our humanized mouse model, alloreactivity was marked by pronounced CD45+ T-cell infiltrates consisting of CD4+ and CD8+ T cells and increased IFN-γ expression in the skin grafts which were all significantly inhibited by both BM-MSC and ASC. CONCLUSION: BM-MSC and ASC are immunosuppressive in vitro and suppress alloreactivity in a preclinical humanized transplantation model.

Human Allogeneic Bone Marrow and Adipose Tissue Derived Mesenchymal Stromal Cells Induce CD8+ Cytotoxic T Cell Reactivity.

INTRODUCTION: For clinical applications, Mesenchymal Stromal Cells (MSC) can be isolated from bone marrow and adipose tissue of autologous or allogeneic origin. Allogeneic cell usage has advantages but may harbor the risk of sensitization against foreign HLA. Therefore, we evaluated whether bone marrow and adipose tissue-derived MSC are capable of inducing HLA-specific alloreactivity. METHODS: MSC were isolated from healthy human Bone Marrow (BM-MSC) and adipose tissue (ASC) donors. Peripheral Blood Mononuclear Cells (PBMC) were co-cultured with HLA-AB mismatched BM-MSC or ASC precultured with or without IFNy. After isolation via FACS sorting, the educated CD8+ T effector populations were exposed for 4 hours to Europium labeled MSC of the same HLA make up as in the co-cultures or with different HLA. Lysis of MSC was determined by spectrophotometric measurement of Europium release. RESULTS: CD8+ T cells educated with BM-MSC were capable of HLA specific lysis of BM-MSC. The maximum lysis was 24% in an effector:target (E:T) ratio of 40:1. Exposure to IFNγ increased HLA-I expression on BM-MSC and increased lysis to 48%. Co-culturing of PBMC with IFNγ-stimulated BM-MSC further increased lysis to 76%. Surprisingly, lysis induced by ASC was significantly lower. CD8+ T cells educated with ASC induced a maximum lysis of 13% and CD8+ T cells educated with IFNγ-stimulated ASC of only 31%. CONCLUSION: Allogeneic BM-MSC, and to a lesser extend ASC, are capable of inducing HLA specific reactivity. These results should be taken into consideration when using allogeneic MSC for clinical therapy.

Uremia causes premature ageing of the T cell compartment in end-stage renal disease patients.

BACKGROUND: End-stage renal disease (ESRD) patients treated with renal replacement therapy (RRT) have premature immunologically aged T cells which may underlie uremia-associated immune dysfunction. The aim of this study was to investigate whether uremia was able to induce premature ageing of the T cell compartment. For this purpose, we examined the degree of premature immunological T cell ageing by examining the T cell differentiation status, thymic output via T cell receptor excision circle (TREC) content and proliferative history via relative telomere length in ESRD patients not on RRT. RESULTS: Compared to healthy controls, these patients already had a lower TREC content and an increased T cell differentiation accompanied by shorter telomeres. RRT was able to enhance CD8+ T cell differentiation and to reduce CD8+ T cell telomere length in young dialysis patients. An increased differentiation status of memory CD4+ T cells was also noted in young dialysis patients. CONCLUSION: Based on these results we can conclude that uremia already causes premature immunological ageing of the T cell system and RRT further increases immunological ageing of the CD8+ T cell compartment in particular in young ESRD patients.

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

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+ naïve T cells. The age-related decrease in the number of CD8+ naïve T cells was CMV-independent. In contrast, all ESRD patients showed a profound naïve T-cell lymphopenia at every decade. CMV-seropositivity aggravated the contraction of CD4+ naïve 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.

Hyponatremia in acute brain disease: the cerebral salt wasting syndrome.

Hyponatremia in acute brain disease is a common occurrence, especially after an aneurysmal subarachnoid hemorrhage. Originally, excessive natriuresis, called cerebral salt wasting, and later the syndrome of inappropriate antidiuretic hormone secretion (SIADH), were considered to be the causes of hyponatremia. In recent years, it has become clear that most of these patients are volume-depleted and have a negative sodium balance, consistent with the original description of cerebral salt wasting. Elevated plasma concentrations of atrial or brain natriuretic peptide have been identified as the putative natriuretic factor. Hyponatremia and volume depletion may aggravate neurological symptoms, and timely treatment with adequate replacement of water and NaCl is essential. The use of fludrocortisone to increase sodium reabsorption by the renal tubules may be an alternative approach.