Enhancing Immune Protection in Hemodialysis Patients: Role of the Polymethyl Methacrylate Membrane

End-stage renal disease (ESRD) is characterized by deep disorders in both innate and adaptive immune systems that imply unbalance deactivation and immunosuppression. The central, widely recognized factors responsible for this immune dysregulation are uremia, uremic toxin retention, hemodialysis membrane biocompatibility, and related cardiovascular complications. Recently, several studies strengthened the concept that dialysis membranes are not considered as a simple diffusive/adsorptive device but as a platform to personalize a dialysis approach to improve the quality of life of ESRD patients. Therefore, understanding of the molecules associated with altered immune response is crucial and could lead to therapeutically intervention or adaptation of the dialysis procedure itself for the management of immunological dysfunction of ESRD patients. The polymethyl methacrylate (PMMA)-based membrane is characterized by a symmetrical structure with large-sized pores, providing a better hydrophobic and cationic adsorption capacity compared to the other synthetic membranes. Together with hydrophobic interactions, the high adsorption rate of cytokines (i.e., IL-6) can also be enhanced by the size of nano-pores placed on the membrane surface. PMMA membranes exhibit adsorptive properties for a large amount of uremic toxins including p-cresol and indoxyl sulfate, as well as β2-microglobulin characterized by higher molecular weight, maintaining the diffusive clearance of small molecules like urea with a great biocompatibility. Besides exerting a strong anti-inflammatory effects in line with the improvement of immune responses in patients undergoing dialysis, PMMA also plays a role in modulating adaptive immune response, i.e., can clear blood from soluble CD40, a natural antagonist of the CD40/CD40L signaling that acts inhibiting immunoglobulin production by B cells. This review provides an overview of the main concepts and current understanding of immune dysfunction in hemodialysis and summarizes the recent findings regarding PMMA-based dialysis as potential strategy to restore immune balance in ESRD patients.

Pregnancy in end-stage renal disease patients on dialysis: how to achieve a successful delivery

Pregnancy in women with chronic kidney disease has always been considered as a challenging event both for the mother and the fetus. Over the years, several improvements have been achieved in the outcome of pregnant chronic renal patients with increasing rates of successful deliveries. To date, evidence suggests that the stage of renal failure is the main predictive factor of worsening residual kidney function and complications in pregnant women. Moreover, the possibility of success of the pregnancy depends on adequate depurative and pharmacological strategies in patients with end-stage renal disease. In this paper, we propose a review of the current literature about this topic presenting our experience as well.

Allograft nephrectomy: what is the best surgical technique?

BACKGROUND

The objective of this study was to evaluate differences in outcomes of allograft nephrectomies performed by extracapsular versus intracapsular techniques.

METHODS

From 1993 to 2010, we performed 89 allograft nephrectomies, including 57 by extracapsular techniques and 32 by intracapsular, chosen according to feasibility at the beginning of the surgery. Fisher exact test and logistic regression were used for statistical analysis. Survival estimates after allograft nephrectomy were calculated according to the Kaplan-Meier method.

RESULTS

After a mean graft survival of 49.7 months, the indications for transplant nephrectomy were chronic rejection (39.3%), acute rejection (22.5%), infection/sepsis (19.1%), gross hematuria (6.7%), renal vein thrombosis (6.7%), renal artery thrombosis (3.4%), and graft rupture (2.3%). Mean operative time, blood loss, transfusions, and complications were similar between the extracapsular and intracapsular groups. The only difference in surgical aspects between the 2 groups was the mean hospital stay, which was longer for the extracapsular group (13.8 vs 7.6 days; P = .01), a result that was confirmed by multivariate analysis (odds ratio, 1.05; 95% confidence interval, 1.0-1.1; P = .03).

CONCLUSIONS

Our experience showed no significant advantages in favor of the intracapsular technique except for a shorter length of hospital stay than after the extracapsular procedure.

Impact of transplant nephrectomy on retransplantation: a single-center retrospective study

PURPOSE

Kidney retransplantation is the best treatment option for transplanted patients returning to dialysis. The aim of this study was to explore the effect of removal of a failed graft on the outcome of a subsequent transplant.

METHODS

We identified 140 patients who underwent retransplantation at our institution. Retrospective comparison was performed between patients undergoing kidney retransplantation with (group A, n = 28) and without (group B, n = 112) preliminary nephrectomy. Graft and patient survival were calculated by the Kaplan-Meier method.

RESULTS

After a mean follow-up of 64.5 months, patients survival was comparable between the two groups (group A = 68.6 vs. group B = 63.5 months; p = 0.6). Mean graft survival was 65.5 versus 56.0 months in group A and B, respectively (p = 0.14). Surgical complications after retransplantation were significantly higher in group A compared to group B (57.1 vs. 19.6 %; p = 0.0002). There was no significant difference between the two groups in the panel reactive antibody level at the time of retransplantation (group A = 20 % vs. group B = 32 %; p = 0.22). The acute rejection rate was 35.7 % in group A and 25 % in group B (p = 0.36). The risk of delayed graft function was not significantly increased in group A (p = 0.63). Finally, 2 years after retransplantation, patients who had not undergone nephrectomy had lower serum creatinine concentrations (1.3 vs. 1.7 mg/dl; p = 0.01) and higher estimated GFR (77.9 vs. 59.3 ml/min/1.73 m(2); p = 0.02).

CONCLUSION

Our experience shows that there is no advantage in performing allograft nephrectomy before retransplantation, and that this procedure does not seem to significantly influence the survival of a subsequent graft.

Update on pregnancy in chronic kidney disease

The occurrence of pregnancy in patients with chronic kidney disease (CKD) has been considered a dangerous event both for the mother and for the fetus. However, increasing evidence shows that the stage of CKD is the leading factor that can predict possible acceleration in the declining of renal function and complications of pregnancy. This review summarizes recent data on pregnancy in patients with CKD, dialysis and kidney transplantation.