Tumor-derived interleukin-1α and leukemia inhibitory factor promote extramedullary hematopoiesis.

Extramedullary hematopoiesis (EMH) expands hematopoietic capacity outside of the bone marrow in response to inflammatory conditions, including infections and cancer. Because of its inducible nature, EMH offers a unique opportunity to study the interaction between hematopoietic stem and progenitor cells (HSPCs) and their niche. In cancer patients, the spleen frequently serves as an EMH organ and provides myeloid cells that may worsen pathology. Here, we examined the relationship between HSPCs and their splenic niche in EMH in a mouse breast cancer model. We identify tumor produced IL-1α and leukemia inhibitory factor (LIF) acting on splenic HSPCs and splenic niche cells, respectively. IL-1α induced TNFα expression in splenic HSPCs, which then activated splenic niche activity, while LIF induced proliferation of splenic niche cells. IL-1α and LIF display cooperative effects in activating EMH and are both up-regulated in some human cancers. Together, these data expand avenues for developing niche-directed therapies and further exploring EMH accompanying inflammatory pathologies like cancer.

A Novel Model for Nephrotic Syndrome Reveals Associated Dysbiosis of the Gut Microbiome and Extramedullary Hematopoiesis.

Glomerular kidney disease causing nephrotic syndrome is a complex systemic disorder and is associated with significant morbidity in affected patient populations. Despite its clinical relevance, well-established models are largely missing to further elucidate the implications of uncontrolled urinary protein loss. To overcome this limitation, we generated a novel, inducible, podocyte-specific transgenic mouse model (Epb41l5fl/fl*Nphs1-rtTA-3G*tetOCre), developing nephrotic syndrome in adult mice. Animals were comprehensively characterized, including microbiome analysis and multiplexed immunofluorescence imaging. Induced knockout mice developed a phenotype consistent with focal segmental glomerular sclerosis (FSGS). Although these mice showed hallmark features of severe nephrotic syndrome (including proteinuria, hypoalbuminemia and dyslipidemia), they did not exhibit overt chronic kidney disease (CKD) phenotypes. Analysis of the gut microbiome demonstrated distinct dysbiosis and highly significant enrichment of the Alistipes genus. Moreover, Epb41l5-deficient mice developed marked organ pathologies, including extramedullary hematopoiesis of the spleen. Multiplex immunofluorescence imaging demonstrated red pulp macrophage proliferation and mTOR activation as driving factors of hematopoietic niche expansion. Thus, this novel mouse model for adult-onset nephrotic syndrome reveals the significant impact of proteinuria on extra-renal manifestations, demonstrating the versatility of this model for nephrotic syndrome-related research.

Novel findings of splenic extramedullary hematopoiesis during primary myelofibrosis, post-essential thrombocythemia, and post-polycythemia vera myelofibrosis.

BCR-ABL-fusion-negative myeloproliferative neoplasms (MPNs) with myelofibrosis (MF) include primary MF, post-polycythemia vera MF and post-essential thrombocythemia MF. Clonal extramedullary hematopoiesis (EMH) can occur during MPN pathogenesis. Although histopathological bone-marrow (BM) features during clonal EMH have been investigated, those of the spleen have been poorly described. We analyzed splenectomy samples from 28 patients with MF and BM samples from 20 of them. Slides were stained with hematoxylin and eosin, reticulin, and trichrome, with immunohistochemical labeling of glycophorin A, myeloperoxidase, CD61, CD34, and CD117. We also subjected splenectomy and BM samples from six patients and spleen samples from seven patients to next-generation sequencing (NGS). Megakaryocyte-rich spleen nodules (MRSNs), seen in seven of the 28 patients, were significantly associated with megakaryocyte proliferation in the spleen (p = 0.04). We devised a grading system for spleen fibrosis (SF) and found that SF was increased in 20 of 28 patients. Notably, patients with SF were more likely to have MRSNs, suggesting that megakaryocytes might participate in SF, as previously described in BM. Comparisons of spleen and BM NGS findings of six patients' specimens revealed identical mutational status in the two organs for half of the patients. We observed additional mutations in the spleen of two patients. However, the meaning of this finding remains unknown since there was a long interval between BM and spleen samplings (68 and 82 months, respectively).

Assessment of medullary and extramedullary myelopoiesis in cardiovascular diseases.

Recruitment of innate immune cells and their accumulation in the arterial wall and infarcted myocardium has been recognized as a central feature of atherosclerosis and cardiac ischemic injury, respectively. In both, steady state and under pathological conditions, majority of these cells have a finite life span and are continuously replenished from haematopoietic stem/progenitor cell pool residing in the bone marrow and extramedullary sites. While having a crucial role in the cardiovascular disease development, proliferation and differentiation of innate immune cells within haematopoietic compartments is greatly affected by the ongoing cardiovascular pathology. In the current review, we summarize key cells, processes and tissue compartments that are involved in myelopoiesis under the steady state, during atherosclerosis development and in myocardial infarction.

Extramedullary Hematopoiesis Causing Spinal Cord Compression.

Spinal cord compression due to extramedullary hematopoiesis is a rare neurosurgical problem that is successfully treated with urgent decompression. Here we report the case of a young man with hemoglobin Lepore disease and beta thalassemia who presented with 1 month of lower extremity weakness and urinary retention. The patient underwent urgent thoracic laminectomies and recovered fully. This pathology can be treated with multiple modalities; however, decompression must remain in the neurosurgeon's armamentarium in the acute setting.

Changes in histidine decarboxylase expression influence extramedullary hematopoiesis in postnatal mice.

Histidine decarboxylase (HDC), histamine synthase, is expressed in hematopoietic stem cells and in lineage-committed progenitors in the bone marrow (BM). However, the role of histamine in hematopoiesis is not well described. To evaluate the role of histamine in hematopoiesis, we analyzed the changes in HDC expression at hematopoietic sites, the BM, spleen, and liver of 2-, 3-, and 6-week-old wild-type mice. We also performed morphological analyses of the hematopoietic sites using HDC-deficient (HDC-KO) mice. In wild-type adults, HDC expression in the BM was higher than that in the spleen and liver and showed an age-dependent increase. Histological analysis showed no significant change in the adult BM and spleen of HDC-KO mice compared to wild-type mice. In the liver, HDC expression was temporarily increased at 3 weeks and decreased at 6 weeks of age. Morphological analysis of the liver revealed more numerous hematopoietic colonies and megakaryocytes in HDC-KO mice compared to wild-type mice at 2 and 3 weeks of age, whereas no changes were observed in adults. Most of these hematopoietic colonies consisted of B220-positive B-lymphocytes and TER119-positive erythroblasts and were positive for the cell proliferation marker PCNA. Notably, these hematopoietic colonies declined in HDC-KO mice upon N-acetyl histamine treatment. A significant increase in the expression of hematopoiesis-related cytokines, Il3, Il7, Epo, Gcsf, and Cxcl12 mRNA was observed in the liver of 3-week-old HDC-KO mice compared to wild-type mice. These results suggest that histamine-deficiency may maintain an microenvironment suitable for hematopoiesis by regulating hematopoiesis-related cytokine expression in the liver of postnatal mice.

Contribution of Extramedullary Hematopoiesis to Atherosclerosis. The Spleen as a Neglected Hub of Inflammatory Cells.

Cardiovascular diseases (CVDs) incidence is becoming higher. This fact is promoted by metabolic disorders such as obesity, and aging. Atherosclerosis is the underlying cause of most of these pathologies. It is a chronic inflammatory disease that begins with the progressive accumulation of lipids and fibrotic materials in the blood-vessel wall, which leads to massive leukocyte recruitment. Rupture of the fibrous cap of the atherogenic cusps is responsible for tissue ischemic events, among them myocardial infarction. Extramedullary hematopoiesis (EMH), or blood cell production outside the bone marrow (BM), occurs when the normal production of these cells is impaired (chronic hematological and genetic disorders, leukemia, etc.) or is altered by metabolic disorders, such as hypercholesterolemia, or after myocardial infarction. Recent studies indicate that the main EMH tissues (spleen, liver, adipose and lymph nodes) complement the hematopoietic function of the BM, producing circulating inflammatory cells that infiltrate into the atheroma. Indeed, the spleen, which is a secondary lymphopoietic organ with high metabolic activity, contains a reservoir of myeloid progenitors and monocytes, constituting an important source of inflammatory cells to the atherosclerotic lesion. Furthermore, the spleen also plays an important role in lipid homeostasis and immune-cell selection. Interestingly, clinical evidence from splenectomized subjects shows that they are more susceptible to developing pathologies, such as dyslipidemia and atherosclerosis due to the loss of immune selection. Although CVDs represent the leading cause of death worldwide, the mechanisms involving the spleen-atherosclerosis-heart axis cross-talk remain poorly characterized.

[Development of sarcoma on a ectopic extramedullary hematopoiesis secondary to hereditary spherocytosis: Case report and literature review]. / Développement d'un sarcome sur foyer ectopique hématopoïétique secondaire à une sphérocytose héréditaire : à propos d'un cas et revue de la littérature.

INTRODUCTION: Extramedullary hematopoiesis is a complication of myeloproliferative neoplasms or of chronic hemolysis. The more frequent localizations are splenic, ganglionic or paraspinal. Rarely, extramedullary hematopoiesis is associated with solid cancer. CASE REPORT: We report an original case of sarcoma located in an extramedullary hematopoiesis mass in a 72-year-old woman suffering from hereditary spherocytosis. An asymptomatic right paravertebral mass was found in 2004; the biopsy confirmed extramedullary hematopoiesis. In 2016, the patient was hospitalized due to paravertebral pain. Computed tomography showed the extension of the right paraspinal mass to pleura and mediastinum as well as vertebral bone lysis. Positron emission tomography showed an intense hypermetabolism. The biopsy showed undifferentiated sarcoma. CONCLUSION: This case report illustrates the risk of neoplastic transformation of extramedullary hematopoiesis, and the need for a biopsy when confronted to atypical aspect.

The role of AGK in thrombocytopoiesis and possible therapeutic strategies.

Abnormal megakaryocyte development and platelet production lead to thrombocytopenia or thrombocythemia and increase the risk of hemorrhage or thrombosis. Acylglycerol kinase (AGK) is a mitochondrial membrane kinase that catalyzes the formation of phosphatidic acid and lysophosphatidic acid. Mutation of AGK has been described as the major cause of Sengers syndrome, and the patients with Sengers syndrome have been reported to exhibit thrombocytopenia. In this study, we found that megakaryocyte/platelet-specific AGK-deficient mice developed thrombocytopenia and splenomegaly, mainly caused by inefficient bone marrow thrombocytopoiesis and excessive extramedullary hematopoiesis, but not by apoptosis of circulating platelets. It has been reported that the G126E mutation arrests the kinase activity of AGK. The AGK G126E mutation did not affect peripheral platelet counts or megakaryocyte differentiation, suggesting that the involvement of AGK in megakaryocyte development and platelet biogenesis was not dependent on its kinase activity. The Mpl/Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (Stat3) pathway is the major signaling pathway regulating megakaryocyte development. Our study confirmed that AGK can bind to JAK2 in megakaryocytes/platelets. More interestingly, we found that the JAK2 V617F mutation dramatically enhanced the binding of AGK to JAK2 and greatly facilitated JAK2/Stat3 signaling in megakaryocytes/platelets in response to thrombopoietin. We also found that the JAK2 JAK homology 2 domain peptide YGVCF617CGDENI enhanced the binding of AGK to JAK2 and that cell-permeable peptides containing YGVCF617CGDENI sequences accelerated proplatelet formation. Therefore, our study reveals critical roles of AGK in megakaryocyte differentiation and platelet biogenesis and suggests that targeting the interaction between AGK and JAK2 may be a novel strategy for the treatment of thrombocytopenia or thrombocythemia.

Marrow outside marrow: imaging of extramedullary haematopoiesis.

Extramedullary haematopoiesis (EMH) refers to the formation of non-neoplastic blood cell lines outside the bone marrow and is a common incidental finding when patients with haematological disorders are imaged. EMH presenting as mass (tumefactive EMH) has long been a radiological conundrum as it resembles neoplasms. Several imaging findings have been described in EMH, and these vary depending on the activity of the underlying haematopoiesis. The older lesions are easier to diagnose as they often demonstrate characteristic findings such as haemosiderin and fat deposition. In comparison, the newer, actively haematopoietic lesions often mimic neoplasms. Molecular imaging, particularly 99mTc labelled sulphur colloid scintigraphy, may be helpful in such cases. Although imaging is extremely useful in detecting and characterising EMH, imaging alone is often non-diagnostic as no single mass shows all the typical findings. Hence, a judgement based on the clinical background, combination of imaging findings, and slow interval growth may be more appropriate and practical in making the correct diagnosis. In every case, an effort has to be made in providing an imaging-based diagnosis as it may prevent a potentially risky biopsy. When confident differentiation is not possible, biopsy has to be resorted to. This article describes the causes, pathophysiology, and theories underlying the genesis of EMH, followed by the general and location-specific imaging findings. The purpose is to provide a thorough understanding of the condition as well as enable the clinical radiologist in making an imaging-based diagnosis whenever possible and identify the situations where biopsy has to be performed.

GM-CSF drives dysregulated hematopoietic stem cell activity and pathogenic extramedullary myelopoiesis in experimental spondyloarthritis.

Dysregulated hematopoiesis occurs in several chronic inflammatory diseases, but it remains unclear how hematopoietic stem cells (HSCs) in the bone marrow (BM) sense peripheral inflammation and contribute to tissue damage in arthritis. Here, we show the HSC gene expression program is biased toward myelopoiesis and differentiation skewed toward granulocyte-monocyte progenitors (GMP) during joint and intestinal inflammation in experimental spondyloarthritis (SpA). GM-CSF-receptor is increased on HSCs and multipotent progenitors, favoring a striking increase in myelopoiesis at the earliest hematopoietic stages. GMP accumulate in the BM in SpA and, unexpectedly, at extramedullary sites: in the inflamed joints and spleen. Furthermore, we show that GM-CSF promotes extramedullary myelopoiesis, tissue-toxic neutrophil accumulation in target organs, and GM-CSF prophylactic or therapeutic blockade substantially decreases SpA severity. Surprisingly, besides CD4+ T cells and innate lymphoid cells, mast cells are a source of GM-CSF in this model, and its pathogenic production is promoted by the alarmin IL-33.

Extramedullary hematopoiesis: Clinical and cytological features.

INTRODUCTION: Hematopoiesis usually occurs in bone marrow in adults and when it occurs at sites except for bone marrow, it is termed as extramedullary hematopoiesis (EMH). It is usually found in organs, which are vigorously involved in fetal hematopoiesis, including liver, spleen, and lymph nodes. FNAC is easy and rapid method to diagnose EMH. AIM: To study the spectrum of extramedullary hematopoiesis (EMH) on fine-needle aspiration cytology (FNAC). MATERIAL AND METHODS: A total of 10 patients who were diagnosed with EMH on FNAC were studied over a period of 5.5 years. Smears were stained with May Grunwald Giemsa (MGG) and Hematoxylin and Eosin (H and E). The detailed clinical and cytomorphological spectrum of EMH were studied. RESULTS: The mean age of the patient was 42.5 years, with age ranging between 14 and 78 years. The commonest site of EMH was lymph node (n = 8, 80%) followed by paravertebral area (n = 2, 20%). Clinical diagnosis was EMH in just one case. Mean hemoglobin of the patient was 7.9 g/L. Bone marrow examination was available in 6 cases. On FNAC, we saw variable mixture of bone marrow elements including megakaryocytes (2.6%, 0-6%), myelocytes and metamyelocytes (29.2%, 18-33%), erythroid precursors (3.2%, 0-7%), polymorphs (21.7%, 10-36%), blasts (1.1%, 0-4%), eosinophils (2.5%, 0-7%), and lymphocytes (39.7%, 21-60%). CONCLUSION: Cytopathologists must be alert of the clinical as well as cytological spectrum of extramedullary hematopoiesis for greater accuracy in diagnosis and to escape pitfalls in its diagnosis.

A large intrathoracic extramedullary hematopoiesis in alpha-thalassemia: A case report.

RATIONALE: Extramedullary hematopoiesis (EMH) is a rare disease characterized by the formation of hematopoietic elements outside the bone marrow driven by several hematological disease. To the best of our knowledge, EMH is relatively common in patient with beta-thalassemia or hereditary spherocytosis but rarely reported in patients with alpha-thalassemia. Here, we discuss a large intrathoracic EMH (measuring 95 mm × 66 mm) without presenting severe complications in alpha-thalassemia along with literature review. PATIENT CONCERNS: A 55-year-old Chinese female patient with alpha-thalassemia presented with ipsilateral pleural effusion and low hemoglobin level. DIAGNOSIS: Lung cancer was suspected at first and the mass was subjected to CT-guided percutaneous mediastinum biopsy and the pathology confirmed the final diagnosis of extramedullary hematopoiesis. INTERVENTIONS: Blood transfusion, thoracentesis and regular follow up were scheduled rather than surgical interventions or radiotherapy since our patient did not exhibit significant symptoms. OUTCOMES: After 6 months' regular follow up, the patient exhibited no evidence of disease progress. LESSONS: EMH is frequently misdiagnosed and should be differentiated from other masses in thoracic cavity, especially when the underlying hematological disease is discovered. Treatment methods of EMH include surgical resection, hyper-transfusion, hydroxyurea, low-dose radiation or a combination of them.

Compresión medular con paraparesia reversible en paciente con Beta-talasemia / Reversible paraparesis secondary to spinal cord compression in a patient with Beta-thalassaemia

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Erythropoiesis and Iron Homeostasis in Non-Transfusion-Dependent Thalassemia Patients with Extramedullary Hematopoiesis.

BACKGROUND: Extramedullary hematopoiesis (EMH) is common in non-transfusion-dependent thalassemia (NTDT) patients. Clinical presentations of EMH vary as MRI screening is not feasible. Hence, serum biomarkers are used to predict the risk of EMH. MATERIALS AND METHODS: 52 NTDT patients, including 26 EMH (+) and 26 EMH (-), together with 26 healthy controls, were enrolled in this case-control study from 2013 to 2016. EMH was confirmed by computed tomography or MRI. Demographic, transfusion, genetic, laboratory, and liver iron concentration (LIC) data, as well as clinical complications, were analyzed. RESULTS: EMH (+) patients had significantly higher serum ferritin (SF), growth differentiation factor 15 (GDF15), and erythropoietin (EPO) levels compared with EMH (-) patients and controls. The levels of erythroferrone (ERFE), hepcidin, and sTfR did not differ significantly between EMH (+) and EMH (-) patients (p>0.05). In NTDT patients, serum ERFE was not related to SF, LIC, hepcidin, sTfR, EPO, GDF15, and Hb levels. GDF15, EPO concentrations, and GDF15 to sTfR and GDF15 to EPO ratios are able to determine the presence of EMH with considerable sensitivity and specificity. CONCLUSIONS: GDF15, EPO, and GDF15 to EPO and GDF15 to sTfR ratios are potential biomarkers for the early prediction of NTDT in patients who are at risk for EMH.

α-Smooth muscle actin expression predicts the outcome of Kasai portoenterostomy in biliary atresia.

BACKGROUND/AIMS: Biliary atresia (BA) is a cholangio-destructive disease of the infant liver presenting with features of obstructive cholangiopathy. The Kasai portoenterostomy (KPE) is the first line of management. The aim of our study was to identify the characteristic features of liver histology in BA that impact the outcome of KPE. PATIENTS AND METHODS: Data from 30 consecutive children was retrieved from our prospectively maintained database of children undergoing KPE. This included basic demographics, laboratory values and histopathological data from liver biopsy. The stages of fibrosis, presence of ductal plate malformation (DPM), giant cell transformation, extramedullary hematopoiesis and area percentage of α-SMA (α-smooth muscle actin) expression was correlated with jaundice clearance after KPE using standard statistical tests. Native liver survival was computed. RESULTS: Overall, 13 (43%) children cleared jaundice in this series and 10 (33%) are alive with native liver. Lower area percent expression of α-SMA correlated with increased probability of jaundice clearance after KPE (P < 0.001). There was no correlation between stage of fibrosis and jaundice clearance (P = 0.52). DPM, giant cell transformation and extramedullary hematopoiesis did not correlate with outcome. All children who are alive with native liver had lower expression of α-SMA. CONCLUSION: α-SMA expression may be a potential predictor of jaundice clearance and native liver survival after KPE.

Hodgkin lymphoma with co-existing extramedullary haematopoiesis in a Thalasaemia Major patient: Killing two birds with one stone using PET-CT.

Hodgkin lymphoma is a high grade lymphoma which is usually confined to the lymphnodes. Extranodal involvement of the Hodgkin lymphoma is uncommon but any organ can be involved.. Extramedullary haematopoiesis is the production of red cells outside the medullary cavity in response to failure of erythrogenesis in bone marrow which can occur due to many diseases with thalassaemia and myelofibrosis being most common. We present a case of a 21 year old patient who underwent PET-CT scan for the staging of Hodgkin lymphoma and revealed co-existing extramedullary haematopoiesis secondary to known thalassaemia.

Extramedullary hematopoiesis of the sphenoid sinus associated with hereditary spherocytosis: A case report.

Extramedullary hematopoiesis is a rare cause of a sinonasal mass that presents unique diagnostic and treatment challenges. While there are numerous reports of patients with hereditary spherocytosis developing extramedullary hematopoiesis in the posterior mediastinum, involvement in the paranasal sinuses has not previously been described. Here, we present the first case of a patient with hereditary spherocytosis developing extramedullary hematopoiesis in the sphenoid sinus.