Steroid elimination is coming of age

Glucocorticoids Decrease Longitudinal Bone Growth in Pediatric Kidney Transplant Recipients by Stimulating the FGF23/FGFR3 Signaling Pathway

Renal transplantation (RTx) is an effective therapy to improve clinical outcomes in pediatric patients with terminal chronic kidney disease. However, chronic immunosuppression with glucocorticoids (GCs) reduces bone growth and BMD. The mechanisms causing GC-induced growth impairment have not been fully clarified. Fibroblast growth factor 23 (FGF23) is a peptide hormone that regulates phosphate homeostasis and bone growth. In pathological conditions, FGF23 excess or abnormal FGF receptors (FGFR) activity leads to bone growth impairment. Experimental data indicate that FGF23 expression is induced by chronic GC exposure. Therefore, we hypothesize that GCs impair bone growth by increasing FGF23 expression, which has direct effects on bone growth plate. In a post hoc analysis of a multicentric randomized clinical trial of prepubertal RTx children treated with early GC withdrawal or chronic GC treatment, we observed that GC withdrawal was associated with improvement in longitudinal growth and BMD, and lower plasma FGF23 levels as compared with a chronic GC group. In prepubertal rats, GC-induced bone growth retardation correlated with increased plasma FGF23 and bone FGF23 expression. Additionally, GC treatment decreased FGFR1 expression whereas it increased FGFR3 expression in mouse tibia explants. The GC-induced bone growth impairment in tibiae explants was prevented by blockade of FGF23 receptors using either a pan-FGFR antagonist (PD173074), a C-terminal FGF23 peptide (FGF23180-205) which blocks the binding of FGF23 to the FGFR-Klotho complex or a specific FGFR3 antagonist (P3). Finally, local administration of PD173074 into the tibia growth plate ameliorated cartilage growth impairment in GC-treated rats. These results show that GC treatment partially reduces longitudinal bone growth via upregulation of FGF23 and FGFR3 expression, thus suggesting that the FGF23/Klotho/FGFR3 axis at the growth plate could be a potential therapeutic target for the management of GC-induced growth impairment in children.

A study on strategies for improving growth and body composition after renal transplantation

Allograft function and metabolic effects of four treatment regimens, namely, methylprednisone (MP) standard dose (MP-STD), deflazacort (DFZ), MP-late steroid withdrawal (MP-LSW), and MP-very low dose (MP-VLD), were evaluated in prepubertal patients. MP was decreased by month 4 post-transplantation to 0.2 mg/kg/day in MP-STD and DFZ patients and to <0.1 mg/kg/day in MP-LSW and MP-VLD patients. Starting in month 16 post-transplant, MP was switched to DFZ in the DFZ group and totally withdrawn in the MP-LSW group. Creatinine clearance diminished in the MP-STD and MP-LSW groups from 77 +/- 6 to 63 +/- 6 ml/min/1.73 m(2)and from 103 +/- 5 to 78 +/- 3 ml/min/1.73 m(2), respectively (p < 0.01 and p < 0.001, respectively). Height increased >0.5 SDS only in the MP-LSW and MP-VLD groups. The body mass index and fat body mass for height-age increased only in the MP-STD patients (p < 0.05 and p < 0.01, respectively). Fat body mass decreased in the DFZ group (p < 0.05), total cholesterol and LDL-cholesterol increased in the MP-STD group, while LDL-cholesterol and total cholesterol/HDL-cholesterol ratio decreased in the DFZ group (p < 0.01). Lumbar spine bone mineral density (BMD) for height-age showed an increase in the MP-LSW and MP-VLD groups (p < 0.01). Our data suggest that MP-LSW and MP-VLD strategies improve linear growth, BMD, the peripheral distribution of fat, and preservation of the bone-muscle unit and maintain the normal lipid profile. The MP-LSW patients had a concerning rate of acute rejections and graft function deterioration in prepubertal patients.

Selective late steroid withdrawal after renal transplantation

Steroid withdrawal (SW) after paediatric renal transplantation (RTPL) is controversial. Selective late SW has been performed in our unit since 1995. The safety and effects of SW were analysed retrospectively in 47 patients undergoing RTPL between 1995 and 2004. Initial immunosuppression consisted of cyclosporine A, azathioprine or mycophenolate mofetil and steroids. Criteria for SW were: (1) stable renal function, (2) time interval after RTPL > or = 1 year, (3) no rejection or time interval after last rejection > or = 1 year and (4) good compliance. SW was performed in 30 patients at an age of 13.5 years (range 4.5-18.5) and 2.2 years (range 1-6.6) after RTPL. After SW, one patient experienced a steroid-sensitive rejection. Follow-up after SW (1.3 year; range 0.25-7.5) showed maintained renal function: glomerular filtration rate at SW and currently was 82 (65-128) and 82 (42-115) ml/min per 1.73 m(2), respectively. The number of patients on antihypertensive treatment did not significantly change (at SW: n = 15; currently: n = 11). Height and body mass index (BMI) remained stable: Median standard deviation score (SDS) for height/BMI at SW and currently was -1.1/0.2 and -0.8/0.1, respectively. Selective late SW was safe regarding renal function and had no significant effect on blood pressure and growth.

Avoiding steroids in pediatric renal transplantation: long-term experience from a single centre

We report our experience in pediatric renal transplantation avoiding steroids whenever possible. Immunosuppression consisted of an initial induction with antithymocyte globulin followed by maintenance therapy with a calcineurin inhibitor and MMF. Steroids were only given to selected patients because of the primary disease, recurrence, rejection, or PTLD. Thirty-four transplants grafted into 32 recipients between 1995 and 2005 were followed for a median of 3.5 yr (range 1-9.8). All patients survived. Graft rejection occurred in 10 cases during the first year post-transplantation and graft survival at one, five, and seven yr was 97, 88 and 88%, respectively. Steroids were given to half of the patients (n = 16); in nine cases due to rejection. Only four patients (13%) were continuously on steroids. Calculated GFR at one to five yr post-transplant were 73, 74, 68, 64, and 70 mL/min/1.73 m(2). Unfortunately PTLD occurred in three patients, but all survived with functioning grafts. Accordingly, our findings indicate that steroid avoidance in pediatric renal transplantation is possible with good results with respect to acute graft rejection as well as long-term graft survival.

Effects of deflazacort vs. methylprednisone: a randomized study in kidney transplant patients

Metabolic effects of deflazacort vs. methylprednisone were studied in prepubertal patients after kidney transplantation. Thirty-one patients participated: 15 received deflazacort and 16 remained on methylprednisone. The study started at a mean of 2.1 years after transplantation, when patients were randomized to either continue with methylprednisone or switch to deflazacort. Height velocity increased more in the deflazacort than in the methylprednisone group only during the first 2 years: 5.4 +/- 0.5 vs. 3.5 +/- 0.3 cm/year, and 4.2 +/- 0.8 vs. 2.2 +/- 0.4 cm/year p=0.007, [by two-way analysis of variance (ANOVA)]. After 2 and 3 years, the number of patients who were overweight increased in the methylprednisone group and decreased in the deflazacort group; p<0.01. Lean body mass increased more in the deflazacort than in the methylprednisone group (p=0.003). Fat body mass increased only in the methylprednisone group (p<0.01). Total cholesterol and low-density-lipoprotein (LDL) cholesterol increased in the methylprednisone group (p<0.05 and p<0.01, respectively). Total and LDL cholesterol were reduced (p<0.01 and p<0.001, respectively), whereas high-density-lipoprotein (HDL) cholesterol increased (p<0.001) during deflazacort therapy. Lumbar spine bone mineral density (BMD) decreased in both groups, but total skeleton BMD decreased only in the methylprednisone group (p<0.001). Finally, normal glucose/insulin ratio, defined as > 7, was associated (p<0.05) with the deflazacort group. Our data suggest that deflazacort therapy might improve linear growth and lean body mass and prevent excessive bone loss and fat accumulation. It also leads to an improvement in lipoprotein profile without reduction in insulin sensitivity.

Chronic allograft nephropathy in paediatric renal transplantation

Chronic allograft nephropathy (CAN) is now the leading cause of renal transplant loss in paediatric transplant recipients. Despite improvements in immunosuppression, which have significantly reduced the incidence of acute rejection, the rates of chronic kidney loss have remained unchanged in paediatric transplant patients over the last 20 years. Chronic allograft nephropathy is a pathological diagnosis of which the key features are tubular atrophy and interstitial fibrosis. More consistent definitions and grading of these through the Banff classification have allowed more rigorous study of the development of chronic allograft nephropathy along with further identification of specific lesions associated with the underlying aetiologies. While initially thought to be primarily due to immune injury, it is now evident that CAN is the end result of a variety of immune and non-immune injuries including ischaemia reperfusion injury, calcineurin inhibitor (CNI) toxicity and infections. Protocol biopsy studies have demonstrated rates of CAN development in children similar to those in adults with comparable underlying pathological processes. This review outlines the current knowledge of CAN within the context of paediatric renal transplantation.

Steroid preservation: the rationale for continued prescribing

Tailored immunosuppression according to risk stratification for optimal outcome for both immunological and non-immunological risk factors should be the ultimate objective for every child in whom renal transplantation is planned. Renal allograft survival is dependent on the appropriate use of immunosuppressive therapy to prevent acute rejection and chronic allograft nephropathy. Unfortunately, all immunosuppressive therapies, including corticosteroids, have unwanted side effects, including infections, malignancy, nephrotoxicity, hypertension, hyperlipidaemia and diabetes mellitus. However, the most worrying side effects of corticosteroids for children, adolescents and their parents are growth retardation and the cosmetic effects. Consequently, achieving immunosuppressive regimens without corticosteroids would be preferable. The major concern for paediatric nephrologists in the 21st century is no longer acute rejection, as the incidence appears to be decreasing, but infection, particularly EBV and the development of post-transplant lymphoproliferative disease (PTLD). With modern immunosuppressive agents in transplantation, rejection is being traded for infection. The long-term outcome data of PTLD with steroid-free and monoclonal antibody protocols is as yet unknown.