We investigated erythropoietin (Epo) response in a cohort of diabetic patients with various types of anemia to approach the pathogenesis of some cases of "unexplained" anemia encountered among diabetics. Serum Epo levels were determined totally in 747 evaluable subjects with normal renal and hepatic function, of whom 694 had anemia. Among anemic patients, 237 were diabetics, while among the 53 nonanemic persons, there were also 21 diabetics. Diabetic and nondiabetic subjects were uniformly balanced in relation to their demographic features and were categorized according to the etiology of their anemia. Hemoglobin (Hb) did not differ between diabetic and nondiabetic subjects in all the etiological groups and in the whole population. Diabetic patients had significantly lower serum Epo levels as compared to nondiabetics (36.5+/-61 vs 69.4+/-191 IU/ml, p<0.0001), and this was true for all etiologic groups of anemia with the exception of patients with myeloproliferative disorders and those with megaloblastic anemia. The natural logarithmic (ln)-EpoxHb component was used as an index of response to anemia and was found to be significantly decreased in almost all subgroups of diabetic patients. Serum Epo levels were also negatively correlated with the percentage of glycosylated Hb, HbA1(C) (r=-0.446), and the correlation was stronger with the ln of serum Epo (r=-0.638, p<0.001). Inappropriately low serum Epo level is a uniform feature in patients with type II diabetes mellitus and may represent a constitutive blunted response to anemia or an altered metabolic rate of Epo, probably as a result of abnormal glycosylation of the cytokine.
Summary
Immune dysfunction, which leads to the suppression of haemopoiesis by cytokines that are secreted by activated T lymphocytes, is considered to play a key role in the pathogenesis of acquired aplastic anaemia (AAA).
We investigated the intracytoplasmic expression of type‐1 [interferon γ (IFN‐γ), interleukin (IL)‐2] and type‐2 (IL‐4, IL‐10) cytokines in CD4+ and CD8+ T cells before and after in vitro activation in 16 patients with AAA and 17 normal controls. Untreated or refractory patients had a significantly higher proportion of unstimulated CD4+ and CD8+ T cells that produced IFN‐γ and IL‐2 whereas the IL‐4 and IL‐10 producing T cells did not differ from that of controls, resulting in a shift of IFN‐γ/IL‐4 ratio towards a type‐1 response. Patients in remission had also increased proportion of IFN‐γ‐producing unstimulated CD4+ and CD8+ cells, with a parallel rise of IL‐4‐ and IL‐10‐producing cells and normal IFN‐γ/IL‐4 ratio. These data indicate that, in newly diagnosed and refractory patients with AAA, CD4+ cells are polarized towards a type‐1 response that in turn leads to activation of cytotoxic CD8+ cells and finally to haemopoietic stem cell destruction. The type‐1 response persists in patients in remission although this effect is compensated by the increase of IL‐4 and IL‐10 production.
Apoptosis has been implicated in the pathogenesis of marrow failure in MDS and the coexistence of marrow hypercellularity along with blood cytopenias was seen as evidence of extreme cell death of mainly mature cells in the marrow (ineffective hematopoiesis). We investigated apoptosis in 53 patients with MDS, by using single-step DNA extraction and gel electrophoresis and then by separating fresh marrow mononuclear cells in CD34+ and CD34 − populations and in situ single cell evaluation of the process. We also studied the expression of apoptosis-related genes, in total and separated mononuclear marrow cells and correlated the findings with clinical and laboratory characteristics. Patients with apoptosis had increased marrow cellularity, longer overall survival and a longer period for transformation to AML. In 'good' prognosis MDS patients, total mononuclear marrow cells, as well as isolated populations of CD34+ and CD34 − cells showed significant degrees of apoptosis; in 'poor' prognosis cases, however, apoptosis was evident only in a large percentage of CD34 + marrow cells and not in total or CD34 − cells. Absence of expression of both c-myc and p53 in total marrow cells was associated with significant degrees of apoptosis and in isolated CD34+ and CD34 − marrow cells the phenomenon was inversely correlated with the level of bcl-2 expression. In conclusion, marrow apoptosis is detected in both CD34+ and CD34 − cells in early MDS and seems to be restricted to CD34+ cells in advanced MDS cases.
Background/Aims: Disease-related anemia in chronic lymphocytic leukemia (CLL) occurs when the obvious causes are excluded while its pathogenesis is still obscure. We investigated its underlying mechanisms in 56 untreated patients with CLL. Methods: Bone marrow (BM) lymphocytic infiltration was estimated in trephine biopsies. Serum erythropoietin (EPO) and tumor necrosis factor-α (TNF-α) levels were measured by ELISA. The potential of BM CD34+ to differentiate into erythroid cells was evaluated by methylcellulose-based assays and in liquid cultures supplemented with EPO, SCF, IL-3 ± TNF-α. The response of erythroid precursors to EPO ± TNF-α was assessed by detecting activated key proteins of EPO-EPO receptor signalling pathway using Western Blot and EMSA. Results: Bone marrow lymphocytic infiltration was not exclusively responsible for disease-related anemia and CD34+ cells were intrinsically capable of generating erythroid precursors. Also, no deficiency of serum erythropoietin (EPO) or defective intracellular response of erythroid precursors to EPO ± TNF-α stimulation was observed. Serum TNF-α levels were found increased in anemic CLL patients and TNF-α appeared to directly inhibit the erythroid development in early stages of erythropoiesis. Conclusion: We concluded that CLL-related anemia was not due to intrinsic defects of erythroid precursors, but might result from the direct suppressive effect of TNF-α on the erythroid production.
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