Platelet - derived CD154 antigen in patients with chronic kidney disease

CD40/CD40L Signaling as a Promising Therapeutic Target for the Treatment of Renal Disease

The cluster of differentiation 40 (CD40) is activated by the CD40 ligand (CD40L) in a variety of diverse cells types and regulates important processes associated with kidney disease. The CD40/CD40L signaling cascade has been comprehensively studied for its roles in immune functions, whereas the signaling axis involved in local kidney injury has only drawn attention in recent years. Clinical studies have revealed that circulating levels of soluble CD40L (sCD40L) are associated with renal function in the setting of kidney disease. Levels of the circulating CD40 receptor (sCD40), sCD40L, and local CD40 expression are tightly related to renal injury in different types of kidney disease. Additionally, various kidney cell types have been identified as non-professional antigen-presenting cells (APCs) that express CD40 on the cell membrane, which contributes to the interactions between immune cells and local kidney cells during the development of kidney injury. Although the potential for adverse CD40 signaling in kidney cells has been reported in several studies, a summary of those studies focusing on the role of CD40 signaling in the development of kidney disease is lacking. In this review, we describe the outcomes of recent studies and summarize the potential therapeutic methods for kidney disease which target CD40.

Case studies of clinical hemodialysis membranes: influences of membrane morphology and biocompatibility on uremic blood-membrane interactions and inflammatory biomarkers

End stage renal disease (ESRD) patients depend on hemodialysis (HD) as a life-sustaining treatment, but HD membrane properties play a critical role in blood activation during HD and can lead to severe patient outcomes. This study reports on a series of investigations on the common clinical HD membranes available in Canadian hospitals to explore the key reasons behind their susceptibility to blood activation and unstable cytokine. Clinical HD membranes composed of cellulose triacetate (CTA) and polyvinylpyrrolidone: polyarylethersulfone (PAES: PVP) were thoroughly characterized in terms of morphology and chemical composition. Membrane-surface interactions with uremic blood samples after HD treatment were probed using Fourier Transform Infra-Red (FTIR) and Raman spectroscopic techniques in order to understand changes in chemistry on membrane fibers. In addition, as part of this innovative study, we utilized Molecular Modeling Docking to examine the interactions of human blood proteins and membrane models to gain an in-depth understanding of functional group types responsible for perceived interactions. In-vitro adsorption of fibrinogen on different clinical HD membranes was compared at similar clinical operating conditions. Samples were collected from dialysis patients to ascertain the extent of inflammatory biomarkers released, before, during (30 and 90 min) and after dialysis (4 h). Collected blood samples were analyzed using Luminex assays for the inflammatory biomarkers of Serpin/Antithrombin-III, Properdin, C5a, 1L-1α, 1L-1β, TNF-α, IL6, and vWF. We have likewise incubated uremic blood in vitro with the two membrane materials to determine the impact that membrane materials pose in favor of activation away from the hydrodynamics influences. The results of our morphological, chemical, spectroscopic, and in vitro incubation analyses indicate that CTA membranes have a smoother surface and higher biocompatibility than PAES: PVP membranes, however, it has smaller pore size distribution, which results in poor clearance of a broad spectrum of uremic toxins. However, the rougher surface and greater hydrophilicity of PAES: PVP membranes increases red blood cell rupture at the membrane surface, which promotes protein adsorption and biochemical cascade reactions. Molecular docking studies indicate sulfone functional groups play an important role in the adsorption of proteins and receptors. PAES: PVP membranes result in slower but greater adsorption of fibrinogen, but are more likely to experience reversible and irreversible fouling as well as backfiltration. Our major finding is that a single dialysis session, even with a more biocompatible membrane such as CTA, increases the levels of complement and inflammation factors, but to a milder extent than dialysis with a PAES membrane.

In Vitro Closure Times (PFA-100) Are Different Between Peritoneal Dialysis and Hemodialysis

INTRODUCTION

 Platelet dysfunction is not uncommon in patients with end-stage renal disease (ESRD). Type of renal replacement therapy may have an effect on platelet functions, which has not been well investigated. We evaluated in vitro closure time (CT) differences between peritoneal dialysis (PD) and hemodialysis (HD) patients using platelet function analyzer (PFA-100)and observed a significant difference between these renal replacement therapies.

METHODS

 Patients with ESRD undergoing PD (n = 24) or HD (n = 23) for more than 6 months were included. Blood samples for collagen/epinephrine (Col/EPI) and collagen/adenosine diphosphate (Col/ADP) measurements were obtained before HD at a mid-week session for HD patients and at an outpatient control time for PD patients.

RESULTS

 Three of 24 (12.5%) PD patients and 16 of 23 (69.5%) HD patients had prolonged PFA-100 Col/EPI, p< 0.001. Likewise, 4.2% of PD patients and 87.0% of HD patients had prolonged PFA-100 Col/ADP, p< 0.001. Moreover, the median times of PFA-Col/EPI and PFA-100 Col/ADP were significantly lower in PD patients compared with those of HD patients (p< 0.001). Multivariate analysis showed that the type of renal replacement was a risk factor for both elevated PFA-100 Col/ADP and PFA-100 Col/EPI after adjusted for platelets, hematocrit, and urea (p< 0.001).

CONCLUSIONS

 The type of renal replacement therapy may have an effect on in vitro CTs; therefore, studies including more patients with long-term follow-up are needed to investigate if the difference has any impact on clinical outcomes.