Correction of recurrent angioedema related to C1 esterase inhibitor deficiency as a secondary event following nonmyeloablative allogeneic stem cell transplantation in a patient with myelofibrosis

Hereditary angioedema with an acute attack resolved after bone marrow transplantation for acute myeloid leukemia: a case report

BACKGROUND

Hereditary angioedema (HAE), which is caused by C1-inhibitor (C1-INH) deficiency or dysfunction, is a rare and potentially life-threatening disease. In patients with HAE, excess production of bradykinin causes acute unpredictable recurrent attacks of angioedema in localized regions, including the larynx and intestines. Given the fact that HAE is an autosomal dominant disease, C1-INH produced in patients with HAE is 50% of that produced in healthy individuals. However, most patients with HAE present plasma C1-INH function of < 25% owing to the chronic consumption of C1-INH by kallikrein-kinin, contact, complement, coagulation, and fibrinolysis cascades. Recently, several therapeutic options have been developed for acute attacks and prophylaxis in the treatment of HAE; however, currently, there is no curative therapy for HAE.

CASE PRESENTATION

Here we report the case of a 48-year-old male patient who presented with a long-standing history of HAE and underwent bone marrow transplantation (BMT) for acute myeloid leukemia (AML) at the age of 39 years and has been in complete remission of AML and HAE thereafter. Notably, after BMT, his C1-INH function gradually increased as follows: < 25%, 29%, 37%, and 45.6%. Since his 20 s, he intermittently presented with an acute attack of HAE once every 3 months from the initial attack. Further, after undergoing BMT, the number of acute attacks decreased to twice within 4 years until the age of 45 years, and subsequently, the patient has been free of acute attacks. C1-INH is mainly synthesized by hepatocytes, but it is known to be partially produced and secreted from peripheral blood monocytes, macrophages, endothelial cells, and fibroblasts. We speculate that the C1-INH function may be increased by extrahepatic production of C1-INH, possibly synthesized by differentiated cells derived from hematopoietic and mesenchymal stem cells after BMT.

CONCLUSIONS

This case report supports efforts to focus on extrahepatic production of C1-INH in the next strategy of new treatment development for HAE.

European Society for Immunodeficiencies (ESID) and European Reference Network on Rare Primary Immunodeficiency, Autoinflammatory and Autoimmune Diseases (ERN RITA) Complement Guideline: Deficiencies, Diagnosis, and Management

This guideline aims to describe the complement system and the functions of the constituent pathways, with particular focus on primary immunodeficiencies (PIDs) and their diagnosis and management. The complement system is a crucial part of the innate immune system, with multiple membrane-bound and soluble components. There are three distinct enzymatic cascade pathways within the complement system, the classical, alternative and lectin pathways, which converge with the cleavage of central C3. Complement deficiencies account for ~5% of PIDs. The clinical consequences of inherited defects in the complement system are protean and include increased susceptibility to infection, autoimmune diseases (e.g., systemic lupus erythematosus), age-related macular degeneration, renal disorders (e.g., atypical hemolytic uremic syndrome) and angioedema. Modern complement analysis allows an in-depth insight into the functional and molecular basis of nearly all complement deficiencies. However, therapeutic options remain relatively limited for the majority of complement deficiencies with the exception of hereditary angioedema and inhibition of an overactivated complement system in regulation defects. Current management strategies for complement disorders associated with infection include education, family testing, vaccinations, antibiotics and emergency planning.

Haploidentical Hematopoietic Stem Cell Transplant Complicated by Atypical Hemolytic Uremic Syndrome and Kidney Transplant From the Same Donor With No Immunosuppression but C5 Inhibition

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is life-threatening condition particularly when complicating allograft hematopoietic stem cell transplant (HSCT). In the past, the outcome was very poor with the majority of patients reaching end-stage renal disease or dying with little or no chances of kidney transplant (KTx) due to the high risk of relapse. The availability of C5 inhibition has opened up significant therapeutic opportunities and has improved the outcome particularly if complement dysregulation (CD) is the underlying pathogenetic mechanism.

METHODS

We describe a peculiar case of a girl with aHUS complicating HSCT and her subsequent successful KTx received from the same donor thus performed without immunosuppression but anti-C5 inhibition.

RESULTS

Soon after HSCT performed for acute lymphoblastic leukemia, the patient developed a TMA due to CD and reached end-stage renal disease. After 2 years on dialysis, the patient received a KTx from her father who was already the HSCT donor. Given the full chimerism, no immunosuppressive agent was prescribed except a short (2 days) course of steroids and eculizumab to prevent aHUS relapse. Nine months after the KTx, the patient is well with normal renal function, no immunosuppression and continues eculizumab prevention of aHUS (1 infusion every 21 days).

CONCLUSIONS

All patients with transplant-associated thrombotic microangiopathy should be screened for the causes of CD. C5 inhibition with eculizumab is an important therapeutic resource to manage this complication. When KTx is necessary, immunosuppression can be safely withhold in case of same donor for both grafts and documented full chimerism.

Acquired Complement Regulatory Gene Mutations and Hematopoietic Stem Cell Transplant-Related Thrombotic Microangiopathy

Hematopoietic stem cell transplant-related thrombotic microangiopathy (HSCT-TMA) is a severe complication whose pathophysiology is unknown. We describe 6 patients in which the disease was associated with complement regulatory gene abnormalities received from their respective donors. It is suggested that mutated and transplanted monocyte-derived cells are responsible for production of abnormal proteins, complement dysregulation, and, ultimately, for the disease. This observation might have important drawbacks as far as HSCT-TMA pathophysiology and treatment are concerned.