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Summary The novel immunosuppressant sotrastaurin is a selective inhibitor of protein kinase C isoforms that are critical in signalling pathways downstream of the T cell receptor. Sotrastaurin inhibits nuclear factor (NF)-κB, which directly promotes the transcription of forkhead box protein 3 (FoxP3), the key regulator for the development and function of regulatory T cells (Tregs). Our center participated in a randomized trial comparing sotrastaurin (n = 14) and the calcineurin inhibitor Neoral (n = 7) in renal transplant recipients. We conducted ex vivo mixed lymphocyte reaction (MLR) and flow cytometry studies on these patient samples, as well as in vitro studies on samples of blood bank volunteers (n = 38). Treg numbers remained stable after transplantation and correlated with higher trough levels of sotrastaurin (r = 0·68, P = 0·03). A dose-dependent effect of sotrastaurin on alloresponsiveness was observed: the half maximal inhibitory concentration (IC50) to inhibit alloactivated T cell proliferation was 45 ng/ml (90 nM). In contrast, Treg function was not affected by sotrastaurin: in the presence of in vitro-added sotrastaurin (50 ng/ml) Tregs suppressed the proliferation of alloactivated T effector cells at a 1:5 ratio by 35 versus 47% in the absence of the drug (P = 0·33). Signal transducer and activator of transcription 5 (STAT)-5 phosphorylation in Tregs remained intact after incubation with sotrastaurin. This potent Treg function was also found in cells of patients treated with sotrastaurin: Tregs inhibited the anti-donor response in MLR by 67% at month 6, which was comparable to pretransplantation (82%). Sotrastaurin is a potent inhibitor of alloreactivity in vitro, while it did not affect Treg function in patients after kidney transplantation.

BACKGROUND The common γ-chain (γ(c)) cytokines signal through the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway and play pivotal roles in lymphocyte activation. We investigated the effect of immunosuppressive drugs targeting this pathway, the JAK inhibitor tofacitinib (CP-690,550) and the anti-interleukin (IL)-2R antibody basiliximab, as part of a phase 2 study. METHODS After whole-blood activation with the γ(c) cytokines IL-2, IL-7, and IL-15, STAT5 phosphorylation was determined in T cells of de novo kidney transplantation patients treated with tofacitinib/basiliximab (n=5), calcineurin inhibitor (CNI) (cyclosporine A)/basiliximab (n=4) or CNI (tacrolimus)-based immunosuppression (n=6). The IC(50) for phosphorylated STAT (P-STAT) 5 inhibition by tofacitinib was determined in cytokine-activated CD4(+) and CD8(+) T cells from healthy individuals (n=4). RESULTS IC(50) was 26, 72, and 37 ng/mL for IL-2, IL-7, and IL-15 activation, in CD4(+) T cells, respectively; and 35, 61, and 76 ng/mL for IL-2, IL-7, and IL-15 activation, in CD8(+) T cells, respectively. In kidney transplantation patients, 7 days after starting tofacitinib/basiliximab treatment, cytokine-induced P-STAT5 was inhibited in CD4(+) T cells (92% for IL-2 activation, 60% for IL-7, and 75% for IL-15), which persisted for the 2-month study period. In contrast, CNI/basiliximab treatment did not affect IL-7-activated or IL-15-activated P-STAT5; only IL-2-activated P-STAT5 was reduced by 77% on day 7 and recovered to pretreatment levels within 2 months. CD8(+) T cells showed a comparable profile to CD4(+) T cells. P-STAT5 was not inhibited in CNI-treated control patients. CONCLUSIONS Tofacitinib therapy strongly inhibits γ(c) cytokine-induced JAK/STAT5 activation, whereas basiliximab suppresses IL-2-stimulated activation only. Pharmacodynamic monitoring offers a unique tool to evaluate the biologic effects of immunosuppressive drugs.

This article reports the case of a 57-year-old woman who was diagnosed with primary aldosteronism after renal transplantation. The authors discuss the challenges of diagnosing this syndrome in patients with chronic kidney disease, the importance of identifying this condition owing to its association with cardiovascular risk and renal function impairment, and available treatment options. Background. A 57-year-old woman was referred to a nephrology clinic because of chronic hypokalemia. She had a history of polycystic kidney disease, resistant hypertension, atrial fibrillation, type 2 diabetes, stroke, and end-stage renal disease, and had received a kidney transplant from a deceased donor at the age of 48 years. At presentation, the patient described symptoms of chronic fatigue and muscle aches, but she did not report pareses. Her medications included four antihypertensive agents, glucose-lowering drugs, immunosuppressants, digoxin, a coumarin derivative, and potassium chloride. Investigations. Full history, physical examination, laboratory testing of blood and urine, including aldosterone-torenin ratio, and a saline infusion test. Diagnosis. Primary aldosteronism. Management. Treatment with spironolactone resulted in prompt control of hypertension and hypokalemia, allowing discontinuation of potassium chloride and reduction in antihypertensive medication.

Summary Rabbit anti-thymocyte globulins (rATG) induce CD4+CD25+forkhead box P3 (FoxP3+) regulatory T cells that control alloreactivity. In the present study, we investigated whether rATG convert T cells into functional CD4+CD25+FoxP3+CD127−/low regulatory T cells in the presence of drugs that may hamper their induction and function, i.e. calcineurin inhibitors. CD25neg T cells were stimulated with rATG or control rabbit immunoglobulin G (rIgG) in the absence and presence of tacrolimus for 24 h. Flow cytometry was performed for CD4, CD25, FoxP3 and CD127 and the function of CD25+ T cells was examined in suppression assays. MRNA expression profiles were composed to study the underlying mechanisms. After stimulation, the percentage CD4+CD25+FoxP3+CD127−/low increased (from 2% to 30%, mean, P

Biopsy proven gastro-intestinal involvement of Varicella Zoster Virus (VZV) infection is rare and has not previously been reported in renal transplant recipients. This case report concerns a 65 year old, VZV seronegative, renal transplant recipient who presented with a non-vesicular rash and abdominal pain. Endoscopy revealed gastro-duodenal ulceration and in gastric biopsies VZV-DNA was detected by polymerase chain reaction assay. We conclude that abdominal pain in the absence of vesicular skin lesions may be the presenting symptom of visceral VZV infection, a potentially life threatening disease. To diminish the risk of VZV infection, patients on the waiting list for transplantation who are VZV seronegative or have non-protective VZV-IgG antibody titers, it is advised to vaccinate for VZV prior to transplantation.