Toward dual hematopoietic stem-cell transplantation and solid-organ transplantation for sickle-cell disease

The enigma of sickle cell hepatopathy: Pathophysiology, clinical manifestations and therapy

Sickle cell disease (SCD) is one of the most common genetic disorders in the world predominantly affecting economically disadvantaged populations. There is a notable discrepancy between the growing adult SCD population and available diagnostic and therapeutic interventions for SCD. Sickle cell hepatopathy (SCH) is an all-inclusive term to describe the acute and chronic liver manifestations of SCD. The pathophysiology of SCH follows no defined pattern or sequence that poses challenges to clinicians and researchers alike. Evidence is lacking for this underreported disease at various levels from diagnostic to therapeutic options. This paper reviews the basic pathophysiology, clinical features, biochemical and radiological findings of various SCH manifestations and outlines the management of each condition. Old and new therapy options in SCD including hydroxyurea, red blood cell exchange transfusion, ursodeoxycholic acid, voxelotor, l-glutamine and crizanlizumab have been reviewed to investigate the role of these options in treating SCH. The role of liver transplant, haematopoietic stem cell transplant and gene therapy in SCH patients have been reviewed.

Sickle Cell Disease and Kidney

Sickle cell disease causes several kidney manifestations. They include defects in urine concentration, impaired handling of potassium and hydrogen ion, albuminuria, acute kidney injury, and chronic kidney disease to name a few. Glomerular hyperfiltration, tubular hyperfunctioning, endothelial damage from repeated sickling and vaso-occlusive episodes, and iron-induced proinflammatory changes in the glomerular mesangium and tubulointerstitium are some of the mechanisms of kidney damage. Albuminuria is one of the most and common clinical features of kidney disease and progresses with age. Kidney disease in patients with sickle cell is associated with increased mortality. Annual screening for proteinuria starting at age 10 years and limiting the use of nonsteroidal anti-inflammatory agents and the use of angiotensin-converting enzyme inhibitors may help in early detection and delaying the progression of kidney disease. Adequate hydration, angiotensin-converting enzyme inhibitors, and adequate control of sickle cell are the main stay of treatment for albuminuria. The hemoglobin goal for patients with sickle cell nephropathy is lesser (10 g/dL) than that for patients with chronic kidney disease due to other causes given that a higher hemoglobin level increases viscosity and the risk of precipitating vaso-occlusive episodes. A multidisciplinary approach is recommended for managing patients with sickle cell and kidney diseases.

The Role of CTLA4 and Its Polymorphisms in Solid Organ and Haematopoietic Stem Cell Transplantation

HLA matching, transplantation technique, or underlying disease greatly influences the probability of long-term transplantation success. It has been hypothesised that genetic variation affecting antigen presentation also contributes to the outcomes of both solid organ transplantation and allogeneic haematopoietic stem cell transplantation (AHSCT). Those genes, along with those responsible for innate and adaptive immunity, have become targets of investigation. In this review, we focus on the role of CTLA4 in the process of acute graft rejection and summarise the progress in our understanding of its role in predicting the outcome. We present the results of the latest studies investigating the link between CTLA4 gene variability and AHSCT, as well as organ transplantation outcomes. While some studies found a link between +49 A/G and −318 C/T and transplantation outcomes, comprehensive meta-analyses have failed to present any association. The most recent field reviews suggest that the −1772 T/C (rs733618) CC genotype is weakly associated with a lower risk of acute graft rejection, while +49 A/G might be clinically meaningful when investigated in the context of combinations with other polymorphisms. Studies verifying associations between 12 CTLA4 gene SNPs and AHSCT outcomes present inexplicit results. Some of the most commonly studied polymorphisms in this context include +49 A/G (rs231775) and CT60 A/G (rs3087243). The results signify that, in order to understand the role of CTLA4 and its gene polymorphisms in transplantology, further studies must be conducted.

Tandem Orthotopic Living Donor Liver Transplantation Followed by Same Donor Haploidentical Hematopoietic Stem Cell Transplantation for DOCK8 Deficiency

BACKGROUND

An 11-year-old girl with dedicator of cytokinesis 8 (DOCK8) deficiency was proposed for potentially curative hematopoietic stem cell transplantation (HSCT), the donor being her haploidentical mother. However, end-stage liver disease caused by chronic Cryptosporidium infection required liver transplantation before HSCT.

METHODS

Consequently, a staged approach of a sequential liver transplant followed by a HSCT was planned with her mother as the donor for both liver and HSCT.

RESULTS

The patient successfully underwent a left-lobe orthotopic liver transplant; however, she developed a biliary leak delaying the HSCT. Notably, the recipient demonstrated 3% donor lymphocyte chimerism in her peripheral blood immediately before HSCT. Haploidentical-related donor HSCT performed 2 months after liver transplantation was complicated by the development of acyclovir-resistant herpes simplex virus viremia, primary graft failure, and sinusoidal obstruction syndrome. The patient died from sinusoidal obstruction syndrome-associated multiorgan failure with Candida sepsis on day +40 following HSCT.

CONCLUSIONS

We discuss the many considerations inherent to planning for HSCT preceded by liver transplant in patients with primary immunodeficiencies, including the role of prolonged immunosuppression and the risk of infection before immune reconstitution. We also discuss the implications of potential recipient sensitization against donor stem cells precipitated by exposure of the recipient to the donor lymphocytes from the transplanted organ.

Management of Sickle Cell Intrahepatic Cholestasis: An Argument in Favor of Automated Exchange Transfusion

Sickle cell disease patients are commonly treated at transfusion medicine services, and understanding of the hepatic manifestations of the disease is key for optimal management, specifically, in individuals presenting with sickle cell intrahepatic cholestasis (SCIC). SCIC represents a rare, severe hepatic crisis wherein sinusoidal red cell sickling leads to massive hepatocyte dysfunction and cholestatic laboratory findings. Acute SCIC is defined by abdominal pain with progressive hepatic injury associated with hyperbilirubinemia, renal failure, encephalopathy, and coagulopathy. Patients are generally managed with red blood cell exchange transfusion (RBCEx), when available, as this is a potentially fatal condition. Simple transfusion may be utilized in resource-poor environment or when patients refuse RBCEx. As less than 50 adult cases have been described in the literature, many of them with limited follow-up, randomized clinical trials comparing RBCEx with other treatments are currently unfeasible. Likewise, a chronic form exists, but is less well characterized, and is associated with persistent bilirubinemia and a variable course in terms of progressive hepatic disease. We undertake a brief review of the literature and discuss two cases of SCIC managed with RBCEx at our institution.