Anemia is one of the most common health problems in the primary care setting. Macrocytosis in adults is defined as a red blood cell (RBC) mean corpuscular volume (MCV) >100 femtoliter (fL). ...Macrocytic anemias are generally classified into megaloblastic or nonmegaloblastic anemia. Megaloblastic anemia is caused by deficiency or impaired utilization of vitamin B12 and/or folate, whereas nonmegaloblastic macrocytic anemia is caused by various diseases such as myelodysplastic syndrome (MDS), liver dysfunction, alcoholism, hypothyroidism, certain drugs, and by less commonly inherited disorders of DNA synthesis. Macrocytic anemias are treated with cause‐specific therapies, and it is crucial to differentiate nonmegaloblastic from megaloblastic anemia. Because MDS and myeloid neoplasms commonly affect the elderly, primary care physicians may encounter more cases of macrocytic anemias in the near future, as the older population increases. When MDS is suspected along with leukocytopenia and/or thrombocytopenia with anemia, a hematology consultation may be appropriate.
Summary
Pure red cell aplasia (PRCA) is a syndrome characterized by a severe normocytic anaemia, reticulocytopenia, and absence of erythroblasts from an otherwise normal bone marrow. Primary PRCA, or ...secondary PRCA which has not responded to treatment of the underlying disease, is treated as an immunologically‐mediated disease. Although vigorous immunosuppressive treatments induce and maintain remissions in a majority of patients, they carry an increased risk of serious complications. Corticosteroids were used in the treatment of PRCA and this has been considered the treatment of first choice although relapse is not uncommon. Cyclosporine A (CsA) has become established as one of the leading drugs for treatment of PRCA. However, common concerns have been the number of patients treated with CsA who achieve sustained remissions and the number that relapse. This article reviews the current status of CsA therapy and compares it to other treatments for diverse PRCAs.
Background Activated human eosinophils, as well as neutrophils, can release extracellular chromatin to form DNA traps through cytolytic extracellular trap cell death (ETosis). Although formations of ...neutrophil DNA traps are recognized in patients with various inflammatory conditions, neither the presence of ETosis-derived eosinophil DNA traps in human allergic diseases nor the characteristics of these DNA traps have been studied. Objective We investigated the presence of ETosis-derived DNA traps in eosinophil-rich sinus and ear secretions and the functional attributes of ETosis DNA traps. Methods Eosinophil-rich secretions obtained from patients with eosinophilic chronic rhinosinusitis and eosinophilic otitis media were studied microscopically. In vitro studies of ETosis and DNA trap formation used blood-derived eosinophils and neutrophils, and studies of the binding capacities of DNA traps used labeled bacteria and fluorescent microbeads. Stabilities of DNA traps were evaluated by using fluorescence microscopy. Results Abundant nuclear histone H1–bearing DNA traps formed in vivo in the eosinophilic secretions and contributed to their increased viscosity. In vitro , after brief shear flow, eosinophil ETosis-elicited DNA traps assembled to form stable aggregates. Eosinophil DNA traps entrapped bacteria and fungi and, through hydrophobic interactions, microbeads. In comparison with neutrophil-derived DNA traps, eosinophil DNA traps ultrastructurally exhibited thicker fibers with globular structures and were less susceptible to leukocyte-derived proteolytic degradation, likely because of the lesser protease activities of eosinophils. Conclusions In human allergic diseases local cytolysis of eosinophils not only releases free eosinophil granules but also generates nuclear-derived DNA traps that are major extracellular structural components within eosinophil-rich secretions.
Dear Editor, Allergic bronchopulmonary aspergillosis (ABPA) is a pulmonary disorder caused by exaggerated hypersensitivity to Aspergillus species, namely Aspergillus fumigatus. It is characterized by ...poorly controlled asthma, recurrent pulmonary infiltrates, and bronchiectasis often with thick, viscous eosinophilic mucus plugging. Although the mechanism of this hyperdense mucus generation is poorly understood, the severity of this mucus plugging, which may represent severe inflammation, is associated with recurrent relapse. Extracellular trap cell death (ETosis) of human leucocytes, particularly neutrophils and eosinophils, is a distinct programmed cell death pathway. It is characterized by release of filamentous chromatin structures (DNA traps) in contrast to cell apoptosis. DNA trap formation is considered to be an innate immune reaction by ensnaring microorganisms, although its excess production could be pathogenic. For instance, in thick and viscous airway fluids from patients with cystic fibrosis, large numbers neutrophil-derived DNA traps are present (also called neutrophil extracellular traps; NETs).
Purpose of Review
Charcot-Leyden crystals (CLCs), slender bipyramidal hexagonal crystals, were first described by Jean-Martin Charcot in 1853, predating Paul Ehrlich’s “discovery” of eosinophils by ...26 years. To date, CLCs are known as a classical hallmark of eosinophilic inflammation. CLC protein expresses palmitate cleaving lysophospholipase activity and is a member of the family of S-type lectins, galectin-10. We summarize current knowledge regarding the pathological observations of CLCs and their mechanism of generation focusing on eosinophil cell death.
Recent Findings
The presence of CLCs in vivo has been consistently associated with lytic eosinophils. Recent evidence revealed that cytolysis represents the occurrence of extracellular trap cell death (ETosis), an active non-apoptotic cell death process releasing filamentous chromatin structure. Galectin-10 is a predominant protein present within the cytoplasm of eosinophils but not stored in secretory granules. Activated eosinophils undergo ETosis and loss of galectin-10 cytoplasmic localization results in intracellular CLC formation. Free galectin-10 released following plasma membrane disintegration forms extracellular CLCs. Of interest, galectin-10-containing extracellular vesicles are also released during ETosis. Mice models indicated that CLCs could be a novel therapeutic target for Th2-type airway inflammation.
Summary
The concept of ETosis, which represents a major fate of activated eosinophils, expands our current understanding by which cytoplasmic galectin-10 is crystalized/externalized. Besides CLCs and free galectin-10, cell-free granules, extracellular chromatin traps, extracellular vesicles, and other alarmins, all released through the process of ETosis, have novel implications in various eosinophilic disorders.
Idiopathic pure red cell aplasia (PRCA) and secondary PRCA associated with thymoma and large granular lymphocyte leukemia are generally considered to be immune-mediated. The PRCA2004/2006 study ...showed that poor responses to immunosuppression and anemia relapse were associated with death. PRCA may represent the prodrome to MDS. Thus, clonal hematopoiesis may be responsible for treatment failure. We investigated gene mutations in myeloid neoplasm-associated genes in acquired PRCA. We identified 21 mutations affecting amino acid sequences in 11 of the 38 adult PRCA patients (28.9%) using stringent filtering of the error-prone sequences and SNPs. Four PRCA patients showed 7 driver mutations in TET2, DNMT3A and KDM6A, and 2 PRCA patients carried multiple mutations in TET2. Five PRCA patients had mutations with high VAFs exceeding 0.3. These results suggest that clonal hematopoiesis by stem/progenitor cells might be related to the pathophysiology of chronic PRCA in certain adult patients.
Imatinib mesylate (IM) trough concentration varies among IM-treated chronic myeloid leukemia (CML) patients. Although IM pharmacokinetics is influenced by several enzymes and transporters, little is ...known about the role of pharmacogenetic variation in IM metabolism. In this study, associations between IM trough concentration, clinical response and 11 single-nucleotide polymorphisms in genes involved in IM pharmacokinetics (ABCB1, ABCC2, ABCG2 CYP3A5, SLC22A1 and SLCO1B3) were investigated among 67 Japanese chronic phase CML patients. IM trough concentration was significantly higher in patients with a major molecular response than in those without one (P=0.010). No significant correlations between IM trough concentration and age, weight, body mass index or biochemical data were observed. However, the dose-adjusted IM trough concentration was significantly higher in patients with ABCG2 421A than in those with 421C/C (P=0.015). By multivariate regression analysis, only ABCG2 421A was independently predictive of a higher dose-adjusted IM trough concentration (P=0.015). Moreover, previous studies have shown that the ABCG2 421C>A (p.Q141K) variant is prevalent among Japanese and Han Chinese individuals and less common among Africans and Caucasians. Together, these data indicate that plasma IM concentration monitoring and prospective ABCG2 421C>A genotyping may improve the efficacy of IM therapy, particularly among Asian CML patients.
The traditional paradigm of eosinophils as end-stage damaging cells has mainly relied on their release of cytotoxic proteins. Cytokine-induced cell survival and secretion of granular contents from ...tissue-dwelling eosinophil are thought to be important mechanisms for eosinophilic inflammatory disorders, although the occurrence of cytolysis and its products (i.e., free extracellular granules) has been observed in affected lesions. Recent evidence indicates that activated eosinophils can exhibit a non-apoptotic cell death pathway, namely extracellular trap cell death (ETosis) that mediates the eosinophil cytolytic degranulation. Here, we discuss the current concept of eosinophil ETosis which provides a new look at eosinophilic inflammation. Lessons from eosinophilic chronic rhinosinusitis revealed that ETosis-derived DNA traps, composed of stable web-like chromatin, contribute to the properties of highly viscous eosinophilic mucin and impairments in its clearance. Intact granules entrapped in DNA traps are causing long-lasting inflammation but also might have immunoregulatory roles. Eosinophils possess a way to have post-postmortem impacts on innate immunity, local immune response, sterile inflammation, and tissue damage.
Purpose of Review
Eosinophilic otitis media (EOM) is a refractory disease characterized by the accumulation of eosinophils in middle ear effusion and mucosa. We summarize current knowledge regarding ...the clinical characteristics and management of EOM. Although eosinophil activation in inflamed foci is involved in the pathogenesis of EOM, little is known about the fate of the eosinophils and aftermath of their cell death. We discuss the possibility that eosinophils undergo non-apoptotic cell death that worsens tissue damage and increases effusion viscosity.
Recent Findings
Unlike chronic otitis media, EOM is strongly associated with an allergic background. Corticosteroids are currently the only effective pharmacological treatment, and surgical intervention is often required. Mucosal eosinophils infiltrate extensively into the middle ear cavity where they are stimulated by locally produced activators including interleukin-5 and eotaxin. The eosinophils undergo cytolysis in the effusion, which represents a major fate of activated eosinophils in vivo. Recent data revealed cytolysis could be renamed as extracellular trap cell death (ETosis). ETosis represents suicidal cell death involving total cell degranulation and development of sticky chromatin structures (extracellular traps (ETs)). The characteristics of eosinophil- and neutrophil-derived ET polymers might contribute to the difference in viscosity of secretions between EOM and common chronic otitis media.
Summary
The extracellular products remaining after eosinophil ETosis are an important aspect of EOM pathology. The concept of ETosis also has novel implications for potential therapeutic modalities in various eosinophilic disorders.
Acquired chronic pure red cell aplasia (PRCA) develops idiopathically or in association with other medical conditions, including T cell large granular lymphocytic leukemia (T-LGLL) and thymoma. T ...cell dysregulation is considered a cardinal pathogenesis of PRCA, but genetic–phenotypic associations in T cell abnormalities are largely unclear. We evaluated an extended cohort of 90 patients with acquired PRCA, including 26 with idiopathic, 36 with T-LGLL-associated and 15 with thymoma-associated PRCA, for their T cell immuno-phenotypes, clonalities and
STAT3
mutations. TCR repertoire skewing of CD8
+
T cells was detected in 37.5% of idiopathic, 66.7% of T-LGLL-associated and 25% of thymoma-associated PRCA patients, and restriction to Vβ1 was most prominent (41%). Clonalities of TCRβ or γ chain and
STAT3
mutational status were statistically associated (
P
= 0.0398), and they were detected in all three subtypes. The overall response rate to cyclosporin A was 73.9%, without significant difference by subtypes nor
STAT3
mutational status. The T cell dysregulations, such as TCR repertoire skewing with predominant Vβ1 usage, clonality and
STAT3
mutations, were frequently found across the subtypes, and the close associations between them suggest that these T cell derangements reflect a common pathophysiological mechanism among these PRCA subtypes.
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