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The article explores a specific type of paroxysmal nocturnal haemoglobinuria (PNH) known as ahemolytic PNH or white cell PNH. Unlike typical PNH, this subtype does not exhibit signs of hemolysis but is characterized by bone marrow failure and thrombophilia. The document suggests that this subtype may be caused by a PIGA mutation in a committed progenitor cell rather than a stem cell. The authors recommend considering screening for ahemolytic PNH in cases of thromboembolic events and bone marrow failure without hemolysis. [Extracted from the article]

The article examines the somatic mutations in benign disease. Topics discussed include the serious functional consequences of mutations such as altered organ development and aberrant immune function and disease, presence of somatic STAT3 mutations in expanded T-cell clones in immune-mediated bone marrow failure syndromes, and role of intrinsic errors in cell replication and repair in mutations.

Objectives: To determine fluorescently labeled aerolysin (FLAER) binding and glycophosphatidylinositol-anchored protein expression in bone marrow (BM) cells of healthy volunteers and patients with paroxysmal nocturnal hemoglobinuria (PNH) detected in peripheral blood (PB); compare PNH clone size in BM and PB; and detect PNH in BM by commonly used antibodies.Methods: Flow cytometry analysis of FLAER binding to leukocytes and expression of CD55/CD59 in erythrocytes. Analysis of CD16 in neutrophils and CD14 in monocytes in BM.Results: FLAER binds to all normal BM leukocytes, and binding increases with cell maturation. In PNH, lymphocytic clones are consistently smaller than clones of other BM cells. PNH clones are detectable in mature BM leukocytes with high specificity and sensitivity using common antibodies.Conclusions: PNH clone sizes measured in mature BM leukocytes and in PB are comparable, making BM suitable for PNH assessment. We further demonstrate that commonly used reagents (not FLAER or CD55/CD59) can reliably identify abnormalities of BM neutrophils and monocytes consistent with PNH cells. [ABSTRACT FROM AUTHOR]

The aetiology of paroxysmal nocturnal haemoglobinuria ( PNH) is a somatic mutation in the X-linked phosphatidylinositol glycan class A gene ( PIGA), resulting in global deficiency of glycosyl phosphatidylinositol-anchored proteins ( GPI- APs). This study applied RNA-sequencing to examine functional effects of the PIGA mutation in human granulocytes. CXCR2 expression was increased in GPI- AP- compared to GPI- AP+ granulocytes. Macrophage migration inhibitory factor, a CXCR2 agonist, was significantly higher in plasma of PNH patients. Nuclear factor-κB phosphorylation was upregulated in GPI- AP− compared with GPI- AP+ granulocytes. Our data suggest novel mechanisms in PNH, not obviously predicted by decreased production of the GPI moiety. [ABSTRACT FROM AUTHOR]

VEXAS is a heterogenous disease in its clinical manifestations, with multi-organ involvement and variable marrow dysfunction: responses to therapy will need to be carefully categorized across organ systems. While all included patients treated with azacytidine in this cohort met the criteria for MDS based on WHO 2016, the indication for treatment was uncontrolled inflammation despite chronic corticosteroid therapy in 8/11 cases. VEXAS is a new hematologic disease. [Extracted from the article]

Paroxysmal nocturnal hemoglobinuria ( PNH) is an acquired bone marrow disorder caused by expansion of a clone of hematopoietic cells lacking glycosylphosphatidylinositol ( GPI)-anchored membrane proteins. Multiple lines of evidence suggest immune attack on normal hematopoietic stem cells provides a selective growth advantage to PNH clones. Recently, frequent loss of HLA alleles associated with copy number-neutral loss of heterozygosity in chromosome 6p ( CN-6p LOH) in aplastic anemia ( AA) patients was reported, suggesting that AA hematopoiesis 'escaped' from immune attack by loss of HLA alleles. We report here the first case of CN-6p LOH in a Japanese PNH patient only in GPI-anchored protein positive (59%) granulocytes, but not in GPI-anchored protein negative (41%) granulocytes. CN-6p LOH resulted in loss of the alleles A*02:06- DRB1*15:01- DQB1*06:02, which have been reported to be dominant in Japanese PNH patients. Our patient had maintained nearly normal blood count for several years. Our case supports the hypothesis that a hostile immune environment drives selection of resistant hematopoietic cell clones and indicates that clonal evolution may occur also in normal phenotype (non- PNH) cells in some cases. [ABSTRACT FROM AUTHOR]

The article presents a case study of 24-year-old medical editor with persistent central epigastric pain accompanied by nausea and vomiting after returning from a business trip in Brazil in 2001. The patient was diagnosed with paroxysmal nocturnal hemoglobinuria (PNH) and was instructed to avoid oral contraceptives and pregnancy. She preferred to undergo immunosuppressive therapy instead of bone marrow transplantation after experiencing complications due to her unintended pregnancy.

In paroxysmal nocturnal haemoglobinuria (PNH), chronic destruction of PNH red blood cells (RBCs) by complement leads to anaemia and other serious morbidities. Eculizumab inhibits terminal complement-mediated PNH RBC destruction by targeting C5. In the phase III, double-blind, placebo-controlled, TRIUMPH study, eculizumab reduced haemolysis, stabilized haemoglobin levels, reduced transfusion requirements and improved fatigue in patients with PNH. Herein, we explored the effects of eculizumab on measures of anaemia in patients from the TRIUMPH study and the open-label SHEPHERD study, a more heterogeneous population. Eculizumab reduced haemolysis regardless of pretreatment transfusion requirements and regardless of whether or not patients became transfusion-dependent during treatment ( P < 0·001). Reduction in haemolysis was associated with increased PNH RBC counts ( P < 0·001) while reticulocyte counts remained elevated. Eculizumab-treated patients demonstrated significantly higher levels of haemoglobin as compared with placebo in TRIUMPH and relative to baseline levels in SHEPHERD ( P < 0·001 for each study). Eculizumab lowered transfusion requirement across multiple pretreatment transfusion strata and eliminated transfusion support in a majority of both TRIUMPH and SHEPHERD patients ( P < 0·001). Patients who required some transfusion support during treatment with eculizumab showed a reduction in haemolysis and transfusion requirements and an improvement in fatigue. Eculizumab reduces haemolysis and improves anaemia and fatigue, regardless of transfusion requirements. [ABSTRACT FROM AUTHOR]

We analysed endothelial cell membrane microparticles (ECMP) in the peripheral blood of patients with paroxysmal nocturnal haemoglobinuria (PNH) ( n = 9), aplastic anaemia (AA) ( n = 10), sickle cell disease (SCD) ( n = 8), and healthy donors (HD) ( n = 11). There was no clinically manifested thrombosis in the PNH or AA group, except one cured thrombophlebitis (PNH), while all SCD patients had a history of vaso-occlusive crises. We used three-colour flow cytometry with blood cell-specific antibodies and antibodies to endothelial antigens CD105 and CD144. Phosphatidylserine-positive microparticles were detected using the annexin V-binding (AVB) assay. The population of CD105+AVB+ ECMP was significantly ( P < 0·05) higher in SCD (median: 0·568 × 109/l; 25–75th percentile range: 0·351–0·976 × 109/l) and PNH (0·401 × 109/l ; 0·19–0·441 × 109/l) patients when compared with AA (0·122 × 109/l; 0·061–0·172 × 109/l) or HD (0·180 × 109/l; 0·137–0·217 × 109/l) group. Even more pronounced differences were observed in ECMP exhibiting a marker of inflammatory stimulation CD54 (CD105+CD54+). Similarly, ECMP that exhibited endothelial specific and proteolysis-sensitive antigen CD144 were increased in SCD and PNH, but not in AA. Elevated CD54+ ECMP may reflect the inflammatory status of endothelial cells in SCD and PNH, while CD144+ ECMP could indicate continuous endothelial stimulation and/or injury. Analysis of circulating ECMP appears promising to provide useful information on the status of the vascular endothelium in PNH and SCD. [ABSTRACT FROM AUTHOR]

Paroxysmal nocturnal haemoglobinuria (PNH) results from acquired mutations in the PIG-A gene of an haematopoietic stem cell, leading to defective biosynthesis of glycosylphosphatidylinositol (GPI) anchors and deficient expression of GPI-anchored proteins on the surface of the cell's progeny. Some laboratory and clinical findings have suggested genomic instability to be intrinsic in PNH; this possibility has been supported by mutation analysis of hypoxanthine-guanine phosphoribosyltransferase ( HPRT) gene abnormalities. However, the HPRT assay examines lymphocytes in peripheral blood (PB), and T cells may be related to the pathophysiology of PNH. We analysed the molecular and functional features of HPRT mutants in PB mononuclear cells from eleven PNH patients. CD8 T cells predominated in these samples; approximately half of the CD8 cells lacked GPI-anchored protein expression, while only a small proportion of CD4 cells appeared to derive from the PNH clone. The HPRT mutant frequency (Mf) in T lymphocytes from PNH patients was significantly higher than in healthy controls. The majority of the mutant T lymphocyte clones were of CD4 phenotype, and they had phenotypically normal GPI-anchored protein expression. In PNH patients, the majority of HPRT mutant clones were contained within the V β2 T cell receptor (TCR) subfamily, which was oligoclonal by complementarity-determining region three (CDR3) size analysis. Our results are more consistent with detection of uniform populations of expanded T cell clones, which presumably acquired HPRT mutations during antigen-driven cell proliferation, and not due to an increased Mf in PNH. HPRT mutant analysis does not support underlying genomic instability in PNH. [ABSTRACT FROM AUTHOR]

Background: We tested the safety and efficacy of eculizumab, a humanized monoclonal antibody against terminal complement protein C5 that inhibits terminal complement activation, in patients with paroxysmal nocturnal hemoglobinuria (PNH). Methods: We conducted a double-blind, randomized, placebo-controlled, multicenter, phase 3 trial. Patients received either placebo or eculizumab intravenously; eculizumab was given at a dose of 600 mg weekly for 4 weeks, followed 1 week later by a 900-mg dose and then 900 mg every other week through week 26. The two primary end points were the stabilization of hemoglobin levels and the number of units of packed red cells transfused. Biochemical indicators of intravascular hemolysis and the patients' quality of life were also assessed. Results: Eighty-seven patients underwent randomization. Stabilization of hemoglobin levels in the absence of transfusions was achieved in 49% (21 of 43) of the patients assigned to eculizumab and none (0 of 44) of those assigned to placebo (P<0.001). During the study, a median of 0 units of packed red cells was administered in the eculizumab group, as compared with 10 units in the placebo group (P<0.001). Eculizumab reduced intravascular hemolysis, as shown by the 85.8% lower median area under the curve for lactate dehydrogenase plotted against time (in days) in the eculizumab group, as compared with the placebo group (58,587 vs. 411,822 U per liter; P<0.001). Clinically significant improvements were also found in the quality of life, as measured by scores on the Functional Assessment of Chronic Illness Therapy-Fatigue instrument (P<0.001) and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire. Of the 87 patients, 4 in the eculizumab group and 9 in the placebo group had serious adverse events, none of which were considered to be treatment-related; all these patients recovered without sequelae. Conclusions: Eculizumab is an effective therapy for PNH. (ClinicalTrials.gov number, NCT00122330.) N Engl J Med 2006;355:1233-43. [ABSTRACT FROM AUTHOR]

Objective: To study if telomere length can be used as a surrogate marker for the mitotic history in normal and affected hematopoietic cells from patients with paroxysmal nocturnal hemoglobinuria (PNH). Methods: The telomere length was measured by automated multicolor flow fluorescence in situ hybridization in glycosyl-phosphatidyl-inositol anchored protein (GPI)–negative and GPI-positive peripheral blood leukocytes. Eleven patients were studied, two with predominantly hemolytic PNH and nine with PNH associated with marrow failure. Results: Telomere length in GPI-negative cells was significantly shorter than in GPI-positive cells of the same patient (p < 0.01, n = 11). The difference in telomere length (telomere length in GPI-positive minus telomere length in GPI-negative cells) correlated with the percentage of GPI-negative white blood cells. Conclusion: Our results support the hypothesis that telomere length is correlated to the replicative history of GPI-positive and GPI-negative cells and warrant further studies of telomere length in relation to disease progression in PNH. [Copyright &y& Elsevier]

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired disorder originating from hematopoietic stem cells and is a lifethreating disease characterized by intravascular hemolysis, bone marrow (BM) failure, and venous thrombosis. The etiology of PNH is a somatic mutation in the phosphatidylinositol glycan class A gene (PIG-A) on the X chromosome, which blocks synthesis of the glycolipid moiety and causes deficiency in GPI-anchored proteins. PNH is closely related to aplastic anemia, in which T cells mediate destruction of BM. To identify aberrant molecular mechanisms involved in immune targeting of hematopoietic stem cells in BM, we applied RNA-seq to examine the transcriptome of T cell subsets (CD4+ naive, CD4+ memory, CD8+ naive, and CD8+ memory) from PNH patients and healthy control subjects. Differentially expressed gene analysis in four different T cell subsets from PNH and healthy control subjects showed distinct transcriptional profiles, depending on the T cell subsets. By pathway analysis, we identified novel signaling pathways in T cell subsets from PNH, including increased gene expression involved in TNFR, IGF1, NOTCH, AP-1, and ATF2 pathways. Dysregulation of several candidate genes (JUN, TNFAIP3, TOB1, GIMAP4, GIMAP6, TRMT112, NR4A2, CD69, and TNFSF8) was validated by quantitative real-time RT-PCR and flow cytometry. We have demonstrated molecular signatures associated with positive and negative regulators in T cells, suggesting novel pathophysiologic mechanisms in PNH. These pathways may be targets for new strategies to modulate T cell immune responses in BM failure. [ABSTRACT FROM AUTHOR]

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by intravascular hemolysis, venous thrombosis, and bone marrow failure. Seventeen patients with debilitating PNH, including 8 who were HLA-alloimmunized, underwent a reduced-intensity allogeneic hematopoietic cell transplantation (HCT). All received cyclophosphamide/fludarabine +/- antithymocyte globulin followed by a granulocyte colony-stimulating factor-mobilized HCT from an HLA-matched relative. Glycosylphosphatidylinositol-negative neutrophils were detectable after engraftment but disappeared completely at a median 100 days after transplantation. With a median follow-up of nearly 6 years, 15 patients (87.8%) survived, all without any evidence of PNH, transfusion independent, and off anticoagulation. Allogeneic reduced-intensity HCT remains a curative therapeutic option for PNH patients who are not candidates for eculizumab treatment. [ABSTRACT FROM AUTHOR]

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired genetic disorder of the bone marrow that produces intravascular hemolysis, proclivity to venous thrombosis, and hematopoietic failure. Mutation in the PIG-A gene of a hematopoietic stem cell abrogates synthesis of glycosylphosphoinositol (GPI) anchors and expression of all GPI-anchored proteins on the surface of progeny erythrocytes, leukocytes, and platelets. Urokinase plasminogen activator receptor (uPAR), a GPI-linked protein expressed on neutrophils, mediates endogenous thrombolysis through a urokinase-dependent mechanism. Here we show that membrane GPI-anchored uPAR is decreased or absent on granulocytes and platelets of patients with PNH, while soluble uPAR (suPAR) levels are increased in patients’ plasma. Serum suPAR concentrations correlated with the number of GPI-negative neutrophils and were highest in patients who later develop thrombosis. In vitro, suPAR is released from PNH hematopoietic cells and from platelets upon activation, suggesting that these cells are the probable source of plasma suPAR in the absence of GPI anchor synthesis and trafficking of uPAR to the cell membrane. In vitro, the addition of recombinant suPAR results in a dose-dependent decrease in the activity of single-chain urokinase. We hypothesized that suPAR, prevents the interaction of urokinase with membrane-anchored uPAR on residual normal cells. [Copyright &y& Elsevier]

: ObjectiveCellular prion protein (PrPc) is a glycosylphosphatidylinositol (GPI)-anchored protein (GPI-AP) constitutively expressed by neurons but also in hematopoietic cells. In trasmissible spongiform encephalopathies, the protease-resistant form of prion (PrP s c) converts the host PrPc into the pathologic form. We have investigated PrPc expression in hematopoietic cells from paroxysmal nocturnal hemoglobinuria (PNH). In this disease, due to somatic mutations in PIG-A gene, biosynthesis of the (GPI)-anchor is impaired and affected cells lack membrane expression of all GPI-AP.: MethodsNormal and PNH hematopoietic progenitors and paired wild-type (WT) and PIG-A mutant cell lines were used for analysis of intracellular and surface PrPc expression using flow cytometry and Western blot.: ResultsBy flow cytometry, PrPc was constitutively present on normal CD34+ cells, including more immature CD38dim cells, as well as hematopoietic cell lines. Similar results were obtained in purified CD34+. Phospholipase C treatment confirmed that PrPc was expressed on the membrane via the GPI-anchor. In PNH patients, GPI-AP-deficient CD34+ cells lacked PrPc membrane expression. PIG-A-mutated cell lines (Jurkat, K562, CEBV, AEBV), in contrast to their normal counterparts, did not express surface PrPc. However, we detected intracellular PrPc at approximately equivalent levels in both normal and PIG-A-mutated cells using intracellular flow cytometry and Western blotting.: ConclusionCells and cell lines with PNH phenotype together with their normal counterparts may be a suitable system to explore the function of membrane PrPc in the hematopoietic system. Conversely, PrPc is a good model to elucidate the fate of GPI-AP in PIG-A-deficient cells. [Copyright &y& Elsevier]

: ObjectiveRecently, phenotypically normal CD34 cells from the marrow of patients with paroxysmal nocturnal hemoglobinuria (PNH) were reported to show impaired growth and elevated Fas receptor expression as compared to glycophosphatidylinositol-anchored protein (GPI-AP)-deficient CD34 cells and CD34 cells from normal individuals. These results are consistent with the theory that PNH cells have an intrinsic growth advantage, but their superior expansion in vitro could also be the outcome of selective extrinsic pressure in vivo.: Material and MethodsGrowth characteristics, competitive features, and susceptibility to apoptosis of sorted normal or GPI-AP–deficient CD34+ cells derived from PNH patients were assessed in suspension and methylcellulose cultures.: ResultsWhen we directly compared the growth of patients'' CD34 cells, separated based on expression of GPI-AP CD55 and CD59, in most of the patients studied, mutant CD34 cells showed higher progeny production and outgrew phenotypically normal CD34 cells derived from PNH patients in mixing experiments. However, their proliferation rate did not exceed that of control CD34 cells. To determine whether deficient growth of phenotypically normal CD34 cells in PNH was secondary to a pre-existing in vivo insult, we determined the fraction of apoptotic cells within fresh normal and PNH CD34 cells. Normal CD34 cells from PNH patients showed a high proportion of apoptotic cells and higher Fas expression, while GPI-AP–deficient and control CD34 cells showed similar, low rates of apoptosis. After correction for pre-existing apoptosis, the proliferation potential of normal and PNH CD34 cells was similar.: ConclusionsThese results strongly suggest that clonal expansion of GPI-AP–deficient progenitor cells from PNH patients is due to their selection in the hostile marrow environment of the patient. [Copyright &y& Elsevier]