George Bourikas

Kinetics, function and bone marrow trafficking of CD4+CD25+FOXP3+ regulatory T cells in myelodysplastic syndromes (MDS).

CD4+CD25+FOXP3+ T regulatory cells (Tregs) prevent autoimmunity by restricting overexuberant immune responses, but the same subpopulation can incur detrimental effects on antitumor responses. In both cases, the suppressor potential of Tregs appears to be strongly influenced by their compartmentalization. In myelodysplastic syndromes (MDS), immune deregulation and autoimmunity in the early stages might lead to ineffective hematopoiesis and bone marrow (BM) failure, whereas late-stage disease is characterized by the immune escape of the malignant clone. We show that these two stages of MDS are associated with differential Treg activity. Specifically, we found that in early stage MDS, compared with normal hematopoiesis and late stage MDS, Tregs are dysfunctional and their BM homing through the CXCL12/CXCR4 axis is seriously impaired as a result of CXCR4 downregulation. Conversely, in late stage MDS, Tregs are systemically and locally expanded and retain their function and migratory capacity. Moreover, Treg levels follow the disease course and are significantly reduced in treatment responding patients. Our findings indicate Treg involvement in the pathophysiology of MDS; defective suppressor function and BM trafficking of Tregs may be important in the autoimmune process of early MDS, but increased Treg activity could favor leukemic clone progression in late stage disease.

Over 30% of patients with splenic marginal zone lymphoma express the same immunoglobulin heavy variable gene: ontogenetic implications

We performed an immunogenetic analysis of 345 IGHV-IGHD-IGHJ rearrangements from 337 cases with primary splenic small B-cell lymphomas of marginal-zone origin. Three immunoglobulin (IG) heavy variable (IGHV) genes accounted for 45.8% of the cases (IGHV1-2, 24.9%; IGHV4-34, 12.8%; IGHV3-23, 8.1%). Particularly for the IGHV1-2 gene, strong biases were evident regarding utilization of different alleles, with 79/86 rearrangements (92%) using allele (*)04. Among cases more stringently classified as splenic marginal-zone lymphoma (SMZL) thanks to the availability of splenic histopathological specimens, the frequency of IGHV1-2(*)04 peaked at 31%. The IGHV1-2(*)04 rearrangements carried significantly longer complementarity-determining region-3 (CDR3) than all other cases and showed biased IGHD gene usage, leading to CDR3s with common motifs. The great majority of analyzed rearrangements (299/345, 86.7%) carried IGHV genes with some impact of somatic hypermutation, from minimal to pronounced. Noticeably, 75/79 (95%) IGHV1-2(*)04 rearrangements were mutated; however, they mostly (56/75 cases; 74.6%) carried few mutations (97-99.9% germline identity) of conservative nature and restricted distribution. These distinctive features of the IG receptors indicate selection by (super)antigenic element(s) in the pathogenesis of SMZL. Furthermore, they raise the possibility that certain SMZL subtypes could derive from progenitor populations adapted to particular antigenic challenges through selection of VH domain specificities, in particular the IGHV1-2(*)04 allele.

Alterations of platelet function, number and indexes during acute pancreatitis

Background/Aims: Acute pancreatitis constitutes a systemic inflammatory process which is often accompanied by thrombosis and bleeding disorders. The role of platelets in the pathophysiology of the disease has not been elucidated yet. The present study focuses on two successive end-points: (1) the activation of platelets during acute pancreatitis and (2) the alterations of platelet number and indexes between onset and remission of the disease, which reflect the bone marrow response. Methods: A cohort of 54 patients with acute pancreatitis was enrolled. Cause and severity of the disease (APACHE II score) were estimated. Activated platelet ratio (APR) was estimated using flow cytometry at onset and remission. Platelet number (PLT), mean platelet volume (MPV), platelet large cell ratio (P-LCR) and platelet distribution width (PDW) were collected at onset and remission. Results: The first end-point was reached in patient 14 as APR was found elevated at onset of acute pancreatitis (p = 0.01). The second end-point was fulfilled in patient 12 for MPV, P-LCR and PDW, which were found elevated at remission of the disease (p < 0.01) but not for PLT until the last patient (p = 0.34). Conclusion: Platelets are directly involved in the systemic inflammatory process of acute pancreatitis, which leads to consumption, compensated by an immediate bone marrow response.

Th17 and Foxp3+ T regulatory cell dynamics and distribution in myelodysplastic syndromes

Foxp3(+) T regulatory cells (Tregs) and Th17 cells accumulate synchronously at tumor sites during cancer progression, where their interplay is apparently affecting the efficiency of the antitumor response. In myelodysplastic syndromes, a hematopoietic malignancy of myeloid origin, Tregs are highly increased in the late stages of the disease (L-MDS), but the mechanisms driving Treg expansion and the interaction between Treg and Th17 cell dynamics are still unknown. We demonstrate that the proliferative capacity of Tregs is deficient during the early MDS stages (E-MDS), while in L-MDS it returns to normal levels. In addition, synchronously to Treg expansion, L-MDS patients exhibit increased numbers of functionally competent bone marrow IL-17(+) and FOXP3(+)/IL-17(+) cells, in contrast to E-MDS patients, where Th17 cells are significantly decreased and hypofunctional. Our findings suggest similar kinetics of Treg and Th17 cells between MDS and solid tumors, indicating a common immune pathogenetic pathway between diverse cancer types.

Effect of 4 weeks of basic military training on peripheral blood leucocytes and urinary excretion of catecholamines and cortisol

In this study, we assessed the effects of a 4 week basic military physical training programme for male recruits of the Hellenic Air Force on the number and distribution of circulating immune cells and adrenergic and adrenocortical hormonal responses. One group of recruits (exercised, n  =  48) participated in moderate intermittent physical exercise, whereas a second group (non-exercised controls, n  =  9) performed only light work in the barracks. Both groups participated in the same non-physical, classroom-type training and testing. Military training by the exercised group resulted in significant increases in CD4 +  T-lymphocytes, renal cortisol excretion and the urinary noradrenaline/adrenaline ratio, together with reductions in neutrophils and the neutrophil/lymphocyte ratio. In the exercised group, the urinary noradrenaline/adrenaline ratio correlated positively with the training-induced changes in CD4 +  T-lymphocytes and negatively with changes in the neutrophil/lymphocyte ratio. No significant relationship was found between training-induced increases in cortisol excretion and any of the peripheral blood cell alterations. Our results indicate that 4 weeks of military training consisting of intermittent moderate exercise resulted in a significant increase in CD4 +  T-lymphocytes and reduction in neutrophils. These changes were probably driven by alterations in hormonal status, including the significant impact of sympathetic nervous system activation.

Dynamics of telomere's length and telomerase activity in Philadelphia chromosome negative myeloproliferative neoplasms

Telomere exhaustion and increased telomerase activity are associated with the acquisition of aggressive molecular events in a variety of haematological malignancies. In Philadelphia chromosome negative myeloproliferative neoplasms (Ph(neg)MPNs), telomere dynamics during clonal evolution of these diseases have not yet been fully elucidated. Herein we demonstrated that telomere shortening is a global phenomenon in Ph(neg)MPNs, irrespective of disease phenotype, treatment administration and JAK2V617F mutational status but the presence of additional cytogenetic abnormalities further affects them. Consistent with the above finding, TA was upregulated in CD34+ haemopoietic progenitors from almost all Ph(neg)MPN subgroups compared to healthy donors. Moreover, TL below the cut-off value of 27% could predict disease progression in Ph(neg)MPN patients (PFS at 5 years 39% vs 81%). Thus, TL emerges as a new prognostic marker in Ph(neg)MPN, reflecting probably the genetic instability of highly proliferating MPN clones.

Hydroxyurea (HU) is effective in reducing JAK2V617F mutated clone size in the peripheral blood of essential thrombocythemia (ET) and polycythemia vera (PV) patients

Ph-negative chronic myeloproliferative disorders (PhnegcMPD) are treated according to the estimated vascular risk. The recent discovery of V617F point mutation of the JAK2 kinase, which frequently occurs in these diseases, has not changed their management so far. However, emerging data tend to support a prothrombotic role for the mutation, along with a better response of JAK2V617F mutated patients to hydroxyurea treatment. Our data further support this notion.

Amifostine protects lymphocytes during radiotherapy and stimulates expansion of the CD95/Fas and CD31 expressing T-cells, in breast cancer patients.

Abstract. A large body of experimental research supports the anti-neoplastic activity of cellular and humoral immunity. Disease and therapy-related immune suppression may be important on the treatment outcome or on the subsequent course of the malignant disease. The aim of the study was to investigate the efficacy of amifostine in preventing the immunological toxicity of post-operative radiotherapy (RT) in breast cancer patients. Using flow-cytometry, we examined comparatively the peripheral blood lymphocytic subpopulations in breast cancer patients undergoing conventional post-operative RT versus a hypofractionated accelerated RT scheme combined with amifostine (HypoARC) administration. Despite the higher radiation dose intensity delivered in the HypoARC group, a significant protection of CD4, CD8, CD19 and CD56 subtypes by amifostine was noted. We further focused on two interesting CD4/CD8 subpopulations involved in cellular apoptosis and trans-endothelial migration, namely the CD95/Fas and CD31 positive lymphocytes. Amifostine protected and induced expansion of these subtypes, which could contribute to the maintenance of a high burden of tumor infiltrating lymphocytes during therapy. It is suggested that amifostine effectively protects lymphocytes against RT, which may enhance the efficacy of the latter. The clinical impact of the CD95+ and CD31+ T-cell immunological modulation induced by amifostine requires further investigation.

Oxidised low‐density lipoprotein and arterial function in β‐thalassemia major

Objectives:  Vascular abnormalities such as endothelial dysfunction and arterial stiffness have been described in patients with β‐thalassemia major (β‐TM). Increased concentrations of oxidised low‐density lipoprotein cholesterol (oxLDL) have been observed in those patients, but possible associations between oxLDL and arterial function in β‐TM have not been defined.

Splenectomy for Massive Splenic Infarction Unmasks Paroxysmal Nocturnal Hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disorder characterized by pancytopenia, hemolysis, and thrombosis. Abdominal vein thrombosis is a life-threatening manifestation of this disease. We present a patient with complete spleen necrosis due to thrombosis of the splenic vessels. After splenectomy, other causes of thrombophilia were excluded and the diagnosis of PNH was established. The patient was put on anticoagulation but despite the prophylactic international normalized ratio maintained over the last 18 months of follow-up, he had another episode of intrahepatic thrombosis which was treated with tissue plasminogen activator thrombolysis.