Upfront rituximab therapy for thrombotic thrombocytopenic purpura in systemic lupus erythematosus: a case-based review.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of various autoantibodies and deposition of immune complexes on tissues. Acquired thrombotic thrombocytopenic purpura (TTP) is a life-threatening hematological disorder that rarely develops in SLE, mainly caused by inhibitory or clearing autoantibody against ADAMTS13. Although B cells play critical roles in the pathogenesis of two diseases, the role of B-cell depletion therapy using rituximab (RTX), a chimeric monoclonal antibody targeting CD20, in the management of TTP associated with SLE remains unclear. We present a 27-year-old woman who manifested TTP and nephritis simultaneously at diagnosis of SLE. This patient successfully responded to high-dose glucocorticoids combined with plasma exchange, and early administration of RTX-induced sustained remission of TTP without relapse over 16 months. This literature review in light of our case demonstrates relationship between early intervention with RTX and better treatment response despite the degree of ADAMTS13 activity. Moreover, we discuss the clinical features in TTP associated with SLE, risk factors for the development of TTP in SLE, and possible outcomes based on RTX dose. It is important to consider upfront RTX as a promising treatment strategy for SLE-associated secondary TTP to improve short-term response and long-term prognosis.

Establishment of a Screening System to Identify Novel GATA-2 Transcriptional Regulators.

Hematopoietic stem cells can self-renew and differentiate into all blood cell types. The transcription factor GATA-2 is expressed in hematopoietic stem and progenitor cells and is essential for cell proliferation and differentiation. Heterozygous germline GATA2 mutations induce GATA-2 deficiency syndrome, characterized by monocytopenia, a predisposition to myelodysplasia and acute myeloid leukemia, and a profoundly reduced dendritic cell (DC) population, which is associated with increased susceptibility to viral infections. Because patients with GATA-2 deficiency syndrome could retain a wild-type copy of GATA-2, boosting residual wild-type GATA-2 activity may represent a novel therapeutic strategy for the disease. Here, we sought to establish a screening system to identify GATA-2 activators using human U937 monocytic cells as a potential model of the DC progenitor. Enforced GATA-2 expression in U937 cells induces CD205 expression, a marker of DC differentiation, indicating U937 cells as a surrogate of human primary DC progenitors. Transient luciferase reporter assays in U937 cells reveals a high promoter activity of the -0.5 kb GATA-2 hematopoietic-specific promoter (1S promoter) fused with two tandemly connected GATA-2 +9.9 kb intronic enhancers. We thus established U937-derived cell lines stably expressing tandem +9.9 kb/-0.5 kb 1S-luciferase. Importantly, forced GATA-1 expression, a repressor for GATA-2 expression, in the stable clones caused significant decreases in the luciferase activities. In conclusion, our system represents a potential tool for identifying novel regulators of GATA-2, thereby contributing to the development of novel therapeutic approaches.

High-Throughput siRNA Screening to Reveal GATA-2 Upstream Transcriptional Mechanisms in Hematopoietic Cells.

Hematopoietic stem cells can self-renew and differentiate into all blood cell types. The transcription factor GATA-2 is expressed in both hematopoietic stem and progenitor cells and is essential for cell proliferation, survival, and differentiation. Recently, evidence from studies of aplastic anemia, MonoMAC syndrome, and lung cancer has demonstrated a mechanistic link between GATA-2 and human pathophysiology. GATA-2-dependent disease processes have been extensively analyzed; however, the transcriptional mechanisms upstream of GATA-2 remain less understood. Here, we conducted high-throughput small-interfering-RNA (siRNA) library screening and showed that YN-1, a human erythroleukemia cell line, expressed high levels of GATA-2 following the activation of the hematopoietic-specific 1S promoter. As transient luciferase reporter assay in YN-1 cells revealed the highest promoter activity in the 1S promoter fused with GATA-2 intronic enhancer (+9.9 kb/1S); therefore, we established a cell line capable of stably expressing +9.9 kb/1S-Luciferase. Subsequently, we screened 995 transcription factor genes and revealed that CITED2 acts as a GATA-2 activator in human hematopoietic cells. These results provide novel insights into and further identify the regulatory mechanism of GATA-2.

Fatal visceral varicella-zoster developing early after autologous hematopoietic stem cell transplantation for refractory diffuse large B-cell lymphoma.

A middle-aged woman who had undergone autologous hematopoietic stem cell transplantation (HSCT) 1 month previously suffered severe epigastralgia and relapse of lymphoma. The epigastralgia was not relieved by chemotherapy. Thereafter, her pancreatic and hepatic enzyme levels were markedly elevated and disseminated varicella emerged. Despite acyclovir administration, her general condition deteriorated rapidly and she died. Serum varicella zoster virus (VZV) DNA level was shown to be elevated and a diagnosis of disseminated VZV infection was established postmortem. In patients with severe abdominal pain following HSCT, early suspicion and therapeutic intervention for VZV are important, even in the absence of skin lesions.