Is chronic calcineurin inhibitor toxicity responsible for long-term deterioration of renal function in transplant recipients?

Different experimental multiple trauma models induce comparable inflammation and organ injury

Multiple injuries appear to be a decisive factor for experimental polytrauma. Therefore, our aim was to compare the inflammatory response and organ damage of five different monotrauma with three multiple trauma models. For this, mice were randomly assigned to 10 groups: Healthy control (Ctrl), Sham, hemorrhagic shock (HS), thoracic trauma (TxT), osteotomy with external fixation (Fx), bilateral soft tissue trauma (bsTT) or laparotomy (Lap); polytrauma I (PT I, TxT + HS + Fx), PT II (TxT + HS + Fx + Lap) and one multi-trauma group (MT, TxT + HS + bsTT + Lap). The inflammatory response and organ damage were quantified at 6 h by analyses of IL-6, IL-1β, IL-10, CXCL1, SAA1, HMGB1 and organ injury. Systemic IL-6 increased in all mono and multiple trauma groups, while CXCL1 increased only in HS, PT I, PT II and MT vs. control. Local inflammatory response was most prominent in HS, PT I, PT II and MT in the liver. Infiltration of inflammatory cells into lung and liver was significant in all multiple trauma groups vs. controls. Hepatic and pulmonary injury was prominent in HS, PT I, PT II and MT groups. These experimental multiple trauma models closely mimic the early post-traumatic inflammatory response in human. Though, the choice of read-out parameters is very important for therapeutic immune modulatory approaches.

Late calcineurin inhibitor withdrawal as a strategy to prevent graft loss in patients with suboptimal kidney transplant function

Chronic allograft nephropathy is a major cause of progressive renal failure in renal transplant recipients. Its etiology is multifactorial and may include both immunologic and nonimmunologic causes. In this observational cohort study we set out to see if calcineurin inhibitor withdrawal would reduce the likelihood of graft loss.

METHODS

One hundred and five renal transplant recipients with impaired kidney function (mean serum creatinine 3.0 +/- 0.1 mg/dl) and biopsy-proven chronic allograft nephropathy had the dose of their calcineurin inhibitors, cyclosporine (CSA), or tacrolimus (FK), reduced or discontinued with either the addition of, or continuation of mycophenolate mofetil and low-dose corticosteroids. This intervention occurred at a mean of 29.0 +/- 2.7 months after transplantation. Follow-up after intervention was 54.3 +/- 4.1 months in the reduced CSA group (n = 64), 41.6 +/- 3.2 months in the reduced FK group (n = 28), and 75.5 +/- 6.7 months in the calcineurin inhibitor withdrawal group (n = 13).

RESULTS

There were 24 graft failures in the reduced CSA group, 9 graft failures in the reduced FK group, and 1 graft lost in the calcineurin inhibitor withdrawal group. The unadjusted relative risk for graft failure in the CSA and FK groups combined (confidence interval 1.05-31.6), was 4.07 using the calcineurin inhibitor withdrawal group as the reference, p = 0.05. A Cox proportional hazards model adjusting for baseline covariates including age, gender, race, type of transplant, delayed graft function, baseline blood pressure and random serum glucose and cholesterol demonstrated that only calcineurin inhibitor dose reduction but not withdrawal, older age, delayed graft function, higher serum creatinine at the time of intervention, and higher diastolic blood pressure and serum glucose, correlated with graft loss. Only 6 of the 105 patients developed Banff grade acute rejection. All responded to steroid therapy. We conclude that although this observational cohort study may have a selection bias, late calcineurin inhibitor withdrawal in patients with chronic allograft nephropathy and impaired kidney function appears safe and durable as a treatment strategy to reduce the likelihood of graft failure.

Blood pressure management in the kidney transplant recipient

Hypertension is extremely common after kidney transplantation. It has been observed in up to 80% to 90% of patients. The etiologies are multifactorial but, in large part, rest with the native kidneys, concomitant immunosuppressant drugs, and behavioral factors that promote the development of higher levels of blood pressure, including obesity, salt intake, smoking, and alcohol consumption. There is a direct relationship between kidney allograft failure and level of systolic blood pressure during follow-up. Patients with a systolic blood pressure greater than 180 mmHg have 2-fold greater risk of loss of graft function compared with patients with systolics of less than 140 mmHg. A similar pattern exists for diastolic blood pressure. Some investigators have also demonstrated that higher levels of blood pressure also correlate with an increased risk of acute graft rejection, particularly in African Americans. What is not known is whether more effective control of arterial pressure in the transplant patient will reduce the likelihood of graft loss and improve survival. No prospective outcome trials have ever been performed. However, it is likely, given the marked success of better control of blood pressure in nontransplant patients in reducing cardiovascular death and the rate of progression of kidney disease, that similar benefits will be appreciated in the transplant patient. Given the greater cardiovascular burden in the kidney transplant recipient because of the presence, in many cases, of diabetes and hypertension, perhaps even more risk reduction may be realized with incremental reductions in blood pressure. Preferred treatment strategies for lowering blood pressure depends on the mechanism of action and medical comorbidity. Drugs that block the renin-angiotensin system should be preferentially considered because they may have similar advantages in delaying progressive loss of allograft function, much in the same way they have proven benefits in protecting native kidney function. Treating blood pressure in the kidney transplant recipient is a complicated process because patients are already on multiple medications and many will need 3 to 5 antihypertensive drugs to achieve optimal control of blood pressure, which should preferably be below 130/80 mmHg.