1,721,258 research outputs found
Aplastic anemia: Pathophysiology
No full textBone marrow failure (BMF) syndromes are a heterogeneous group of benign hematological conditions characterized by uni- or multi-lineage marrow and/or peripheral blood cytopenia(s), and can be classified in constitutional or acquired syndromes based on pathophysiology. In inherited diseases, germline mutations occur in the hematopoietic stem and progenitor cell (HSPC) compartment causing a progressive loss of normal hematopoiesis, while in acquired syndromes, HPSC compartment disruption can be caused by an extrinsic direct damage by external cytotoxic agents on the stem cell pool or by an autoimmune attack against HSPCs. Aplastic anemia is an acquired immune-mediated BMF syndrome where marrow disruption is driven by a cytotoxic T cell-mediated autoimmune attack against HSPCs sustained by type I interferons that polarize the immune system toward T helper 1 responses in early phases and then toward T helper 17 and effector memory CD8+ T cell in late stage and severe disease. Cytokines and chemokines also play a crucial role in driving immune responses and HSPC growth inhibition and apoptosis, as described for interferon-γ and tumor necrosis factor α. In this review, we summarize current knowledge on acquired aplastic anemia pathophysiology
Infectious Agents and Bone Marrow Failure: A Causal or a Casual Connection?
No full textAcquired bone marrow failure (BMF) syndromes are considered immune-mediated disorders because hematological recovery after immunosuppressive therapies is the strongest indirect evidence of the involvement of immune cells in marrow failure development. Among pathophysiology hypotheses, immune derangement after chronic antigen exposure or cross-reactivity between viral particles and cellular components are the most accepted; however, epitopes against whom these lymphocytes are directed to remain unknown. In this study, we showed that BMF-associated immunodominant clones, namely the most represented T cells carrying an antigen-specific T-cell receptor (TCR) sequence in a random pool, were frequently associated with those described in various infectious diseases, such as cytomegalovirus (CMV) and Mycobacterium tuberculosis infection. We hypothesize that these pathogens might elicit an autoimmune response triggered by cross-reactivity between pathogen-related components and proteins or might be expanded as an unspecific response to a global immune dysregulation during BMF. However, those frequent intracellular pathogens might not only be passengers in marrow failure development, while playing a central role in starting the autoimmune response against hematopoietic stem cells
Cardiotoxicity of Novel Targeted Hematological Therapies
No full textChemotherapy-related cardiac dysfunction, also known as cardiotoxicity, is a group of drug-related adverse events negatively affecting myocardial structure and functions in patients who received chemotherapy for cancer treatment. Clinical manifestations can vary from life-threatening arrythmias to chronic conditions, such as heart failure or hypertension, which dramatically reduce quality of life of cancer survivors. Standard chemotherapy exerts its toxic effect mainly by inducing oxidative stress and genomic instability, while new targeted therapies work by interfering with signaling pathways important not only in cancer cells but also in myocytes. For example, Bruton's tyrosine kinase (BTK) inhibitors interfere with class I phosphoinositide 3-kinase isoforms involved in cardiac hypertrophy, contractility, and regulation of various channel forming proteins; thus, off-target effects of BTK inhibitors are associated with increased frequency of arrhythmias, such as atrial fibrillation, compared to standard chemotherapy. In this review, we summarize current knowledge of cardiotoxic effects of targeted therapies used in hematology
Spleen sizing by ultrasound scan and risk of pneumococcal infection in patients with chronic GVHD: preliminary observations.
No full textEncapsulated bacteria infections (EBI) can cause severe complications after BMT, usually occurring in patients with chronic GVHD (cGVHD) and attributed to functional hyposplenism. Using ultrasound (US) scan, we measured spleen size in 22 patients transplanted from HLA identical siblings, with or without cGVHD. No patient had received TBI, spleen irradiation or penicillin prophylaxis. Results were correlated with occurrence of EBI during a mean follow-up of 55 months (range 7-93). In the group without cGVHD, the difference between pre- and post-BMT spleen longitudinal diameters was not significant, and no patient developed EBI. In the cGVHD group, post-BMT spleen longitudinal diameters were significantly smaller than those pre-BMT (9.1 ± 1.6 vs 12.3 ± 2.2; P = 0.0005). Out of four patients with cGVHD who showed a major spleen size reduction, two developed a severe infection (an overwhelming sepsis and a pneumococcal meningitis). In our small series, we found a borderline relationship between spleen size reduction and duration of cGVHD (P = 0.06), as well as an increased risk of life-threatening infection in patients with extensive cGVHD and hyposplenism as detected by US scan. We conclude that US scan may be useful to detect spleen size reduction following allogeneic BMT and that penicillin prophylaxis is to be strongly recommended in patients with extensive cGVHD and spleen size reduction, even in those who have not received total body or spleen irradiation
Spleen sizing by ultrasound scan and risk of pneumococcal infection in patients with chronic GvHD: preliminary observations
No full textThe urokinase-receptor in infectious diseases.
No full textCell migration through the extracellular matrix (ECM) or endothelial cells is a basic process in several physiological and pathological events, including the immune host response to pathogens, both in the case of innate and adaptive immunity. The urokinase-type plasminogen activator (uPA) receptor (uPAR) is a GPI-anchored cell-surface receptor largely expressed on most of leukocytes, including monocytes/macrophages, granulocytes, immature dendritic cells. uPAR has been detected also in soluble and cleaved forms, which are increased in several pathologies. uPAR focuses the proteolytic activity of its ligand, the serine-protease uPA, on the cell membrane, thus promoting localized plasminogen activation and allowing the cell to degrade surrounding ECM and to move across physical barriers. However, the discovery that uPAR can bind with high affinity a component of the ECM, vitronectin (VN), and associates to cell surface molecules to activate signalling pathways inside the cells, largely expanded the role that uPAR can play in cell proliferation/survival and adhesion/migration, which are crucial events for an efficient immune response to infectious agents. This review is focused on the expression and possible functions of the various forms of uPAR in infectious diseases
Spleen sizing by ultrasound scan and risk of pneumococcal infection in patients with chronic GvHD: preliminary observations
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All Roads Lead to Interferon-γ: From Known to Untraveled Pathways in Acquired Aplastic Anemia
No full textBone marrow failure (BMF) syndromes are a heterogeneous group of benign hematological conditions with common clinical features including reduced bone marrow cellularity and peripheral blood cytopenias. Acquired aplastic anemia (AA) is caused by T helper(Th)1-mediated immune responses and cytotoxic CD8+ T cell-mediated autologous immune attacks against hematopoietic stem and progenitor cells (HSPCs). Interferon-γ (IFNγ), tumor necrosis factor-α, and Fas-ligand are historically linked to AA pathogenesis because they drive Th1 and cytotoxic T cell-mediated responses and can directly induce HSPC apoptosis and differentiation block. The use of omics technologies has amplified the amount of data at the single-cell level, and knowledge on AA, and new scenarios, have been opened on “old” point of view. In this review, we summarize the current state-of-art of the pathogenic role of IFNγ in AA from initial findings to novel evidence, such as the involvement of the HIF-1α pathway, and how this knowledge can be translated in clinical practice
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