Eculizumab treatment modifies the immune profile of PNH patients

Paroxysmal Nocturnal Haemoglobinuria (PNH) is due to pathological expansion of a stem progenitor bearing a somatic mutation of PIG-A gene involved in the biosynthesis of the glycosyl-phosphatidyl-inositol (GPI) anchor. Numerous data suggest a role for immune-mediated mechanisms in the selection/expansion of GPI-defective clone. Haemolytic anaemia in PNH is dependent on the effect of complement against GPI-defective red cells. Eculizumab, an anti-C5 monoclonal antibody, is dramatically effective in controlling haemolysis and thrombosis, in reducing fatigue and in improving quality of life of patients. However, this therapy presents new challenges that need to be properly faced. Here, we report the decrease in B, Natural Killer (NK) and regulatory T cells (Treg), an altered cytokine profile of invariant-NKT cells (NKTi) and the increasing of C-X-C chemokine receptor type 4 (CXCR4) receptor in PNH patients before the Eculizumab therapy. Treatment significantly affects some of these alterations: after Eculizumab, the number of B lymphocytes, the cytokine secretion of NKTi and CXCR4 expression on CD8 T cells became similar to healthy donors. No effects were observed on NK and Treg. The amplitude of the GPI-defective compartment remained unchanged.

Thrombolytic therapy is effective in paroxysmal nocturnal hemoglobinuria: a series of nine patients and a review of the literature

BACKGROUND

Thrombosis is the major risk factor for death in patients with paroxysmal nocturnal hemoglobinuria. Previous case reports indicate that venous thrombosis in patients with paroxysmal nocturnal hemoglobinuria is amenable to thrombolysis.

DESIGN AND METHODS

We reviewed the outcome of thrombolytic therapy for patients with paroxysmal nocturnal hemoglobinuria who had thromboses refractory to anticoagulation at our institutions.

RESULTS

In this study of 41 patients who had at least one thrombotic event, we confirmed a very high incidence of recurrence despite anticoagulation. Nine patients with thrombosis were regarded as eligible for administration of intravenous tissue plasminogen activator, which was effective in reversing thrombi in all of 15 occasions in which it was given. Serious hemorrhagic complications developed in three cases. At last follow-up visit, of the nine patients treated, three had died, and six were in very good to excellent condition in terms of clinical outcome and radiological findings. The only patient in whom thrombolysis may have contributed to a fatal outcome also had complications of "heparin induced thrombocytopenia with thrombosis", which we diagnosed in three additional patients. In our review of the literature, nine out of 15 patients treated with thrombolysis have had a good outcome.

CONCLUSIONS

Although it is associated with a significant but manageable risk of bleeding, systemic thrombolysis is a highly effective treatment for reversing venous thromboses in patients with paroxysmal nocturnal hemoglobinuria.

Easy genotyping of complement C3 'slow' and 'fast' allotypes by tetra-primer amplification refractory mutation system PCR

Complement C3 'slow' and 'fast' allotypes are associated with immune-mediated disorders and may affect the outcome of renal transplantation. We report a tetra-primer amplification refractory mutation system PCR (T-ARMS-PCR) that provides a rapid, reproducible and cost-effective method to genotype both complement C3 'slow' and 'fast' alleles by a single tube reaction.

Excellent prognosis and prevalence of HCV infection of primary hepatic and splenic non-Hodgkin's lymphoma

BACKGROUND

Primary Hepatic (PHL) and Primary Splenic (PSL) non-Hodgkin's Lymphoma are rare entities. Small series of PHL and PSL have been reported, suggesting a non-fortuitous association with Hepatitis C Virus (HCV) infection. The prognosis is believed to be dismal, with early recurrence and short survival.

PATIENTS

We retrospectively reviewed all PHL and PSL patients diagnosed at our institution between 1990 and 2005.

RESULTS

Twenty-five adult patients were identified, six with PHL and 19 with PSL. Twenty-four patients had a B-cell lymphoma, defined as Diffuse Large B-cell lymphoma in 18. The prevalence of HCV infection was 68% among PSL and 66% among PHL. Combination chemotherapy was the mainstay of treatment for PHL and PSL; all but one patient with PSL underwent splenectomy before chemotherapy. Complete remission was achieved in all the cases after frontline therapy; only four patients relapsed but responded to additional chemotherapy courses. Most patients presented with aggressive histological subtypes; 92% were alive at a median follow up of 79 months. HCV infection did not appear to influence the results of therapy.

CONCLUSION

Our study confirms the rarity of PHL and PSL, shows a high prevalence of HCV infection, and demonstrates that the outcome of patients with PHL and PSL may be favourable.

Paroxysmal nocturnal hemoglobinuria: significant association with specific HLA-A, -B, -C, and -DR alleles in an Italian population

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by the expansion of a PIG-A mutated hematopoietic stem cell. An immune-mediated origin has been suggested for this disease. Because HLA genes represent a susceptibility factor for autoimmunity, we investigated HLA genotype in 42 Italian PNH patients compared with 301 control subjects of the same ethnic origin. A significantly increased frequency of the HLA class I alleles A*0201 (p < 0.05), B*1402 (p < 0.001), and Cw*0802 (p < 0.005), and of the HLA class II DRB1*1501 (p < 0.01) with the linked DQB1*0602 (p </= 0.05) and DRB1*01 (p </= 0.05) with the linked DQB1*0501 (p </= 0.01) alleles, has been observed. Notably, a fourfold increase of the haplotype B*1402, Cw*0802 (p < 0.0005) and a 15-fold increase of the Mediterranean haplotype A*33, B*1402, Cw*0802, DRB1*0102, DQB1*0501 (p < 0.005) was also revealed. This association may provide new insights into the autoimmune pathogenesis of PNH.

Association of -318 C/T and +49 A/G cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms with a clinical subset of Italian patients with systemic sclerosis

Systemic sclerosis (SSc) is a complex and heterogeneous autoimmune disorder with a multi-factorial pathogenesis. Like other autoimmune disorders, the possible role of specific cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms in predisposing to SSc has been hypothesized, but it remains controversial. CTLA-4 promoter (-318C/T) and exon 1 (+49 A/G) polymorphisms have been analysed in 43 Italian females with SSc and in 93 unrelated matched healthy controls by a newly designed tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) method. No significant association has been found with either polymorphisms.Nevertheless, SSc patients without concomitant Hashimoto's thyroiditis (HT) were carrying both the -318T allele (P = 0.031) and the +49 G allele (P = 0.076) more frequently than SSc patients with HT [defined by positivity for anti-thyroperoxidase (TPO) and anti-thyroglobulin (TGA) autoantibodies] than controls. Haplotype analysis confirms this association (P = 0.028), and suggests the predominant role of the -318T, whereas that of the +49 G, if any, seems weak. Thus, in Italian SSc patients the CTLA-4 -318C/T promoter polymorphism appears to be associated with the susceptibility to develop SSc without thyroid involvement. Larger studies are needed to confirm these findings and to clarify whether the -318C/T polymorphism is the functional responsible or whether it reflects the presence of another linked genetic element in the same chromosomal region.

Highly homologous T-cell receptor beta sequences support a common target for autoreactive T cells in most patients with paroxysmal nocturnal hemoglobinuria

Deficiency of glycosylphosphatidylinositol (GPI)-anchored molecules on blood cells accounts for most features of paroxysmal nocturnal hemoglobinuria (PNH) but not for the expansion of PNH (GPI(-)) clone(s). A plausible model is that PNH clones expand by escaping negative selection exerted by autoreactive T cells against normal (GPI(+)) hematopoiesis. By a systematic analysis of T-cell receptor beta (TCR-beta) clonotypes of the CD8+ CD57+ T-cell population, frequently deranged in PNH, we show recurrent clonotypes in PNH patients but not in healthy controls: 11 of 16 patients shared at least 1 of 5 clonotypes, and a set of closely related clonotypes was present in 9 patients. The presence of T-cell clones bearing a set of highly homologous TCR-beta molecules in most patients with hemolytic PNH is consistent with an immune process driven by the same (or similar) antigen(s)-probably a nonpeptide antigen, because patients sharing clonotypes do not all share identical HLA alleles. These data confirm that CD8+ CD57+ T cells play a role in PNH pathogenesis and provide strong new support to the hypothesis that the expansion of the GPI(-) blood cell population in PNH is due to selective damage to normal hematopoiesis mediated by an autoimmune attack against a nonpeptide antigen(s) that could be the GPI anchor itself.

CD157 plays a pivotal role in neutrophil transendothelial migration

Paracellular diapedesis, a key step in leukocyte recruitment to the site of inflammation, occurs at endothelial junctions and is regulated by highly coordinated interactions between leukocytes and endothelium. We found that CD157, a glycosylphosphatidylinositol-anchored ectoenzyme belonging to the NADase/ADP-ribosyl cyclase family, plays a crucial role for neutrophil diapedesis, because its ligation with specific monoclonal antibodies (both on neutrophils or endothelial cells) results in altered neutrophil movement on the apical surface of endothelium and, ultimately, in loss of diapedesis. Real-time microscopy revealed that CD157 behaves as a sort of compass during the interaction between neutrophils and endothelial cells; indeed, following CD157 ligation, neutrophils appear disoriented, meandering toward junctions where they eventually stop without transmigrating. These findings are relevant in vivo because CD157-deficient neutrophils obtained from patients with paroxysmal nocturnal hemoglobinuria are characterized by a severely impaired diapedesis.

Polymorphisms in UGT1A gene family and irinotecan toxicity in patients with advanced colorectal cancer

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Background: The irinotecan active metabolite, SN38, is inactivated through glucuronidation mainly by uridine diphosphate glucuronosyltransferase (UGT) 1A1. The (TA)7 allele of a polymorphism in UGT1A1 promoter has been associated with reduced SN38-glucuronidation rate and more severe toxicity. Since other UGT1A family isoforms, the extrahepatic UGT1A7 and the hepatic UGT1A9, are involved in SN38 glucuronidation, it has been suggested that also polymorphic variants of these genes may affect irinotecan toxicity. Methods: 84 patients with advanced colorectal cancer received an irinotecan-based (180 mg/m2 q.2wks) combination treatment. Polymorphisms of UGT1A1 [(TA)6>7], UGT1A7 [387T > G, 391–2CG > AA, 622T > C] and UGT1A9 [-118(T)9>10, -87G > A, 98T > C, I152G > A] were identified by sequencing on DNA from blood samples obtained under an IRB approved protocol. Toxicity has been graded according to NCI-CT criteria. Results: Patient median age was 64 y (range: 31–82); median PS was 0 (range: 0–2). Severe toxicity (diarrhea or/and neutropenia ≥G3) has been observed in 32 patients: diarrhea in 11, neutropenia in 25 (4 patients had both). The estimated allele frequencies were as follows: UGT1A1, (TA)7 (0.35); UGT1A7, 387T and the completely linked 391–2CG (0.39), 622C (0.39); UGT1A9, -118(T)10 (0.39), -87A (0.05), T98C (0.02), I152A (0.21). Severe toxicity was significantly associated only with: (a) the UGT1A1 (TA)7 allele [severe toxicity in 25% of (TA) 6/6, in 46% of (TA) 6/7, in 55% of (TA) 7/7 (Mantel-Haenszel trend test, P < 0.03)]; and (b) the low activity UGT1A7 622C allele [severe toxicity in 26% of 622 T/T, in 39% of 622 T/C, in 67% of 622 C/C (Mantel-Haenszel, P < 0.02)]. In addition, the analysis of the combined genotypes [(TA)6>7 and 622T > C] has shown severe toxicity in 21% of patients with none of (TA)7 and of 622C alleles, in 43% of patients in which the sum of the number of (TA)7 and of 622C alleles is 1 or 2, in 57% of patients in which this sum is ≥3 (the latter includes all patients with both toxicities) (Mantel-Haenszel, P < 0.02). Conclusions: These data show that both the low activity UGT1A1 (TA)7 and UGT1A7 622C alleles are significantly associated with irinotecan severe toxicity. It is to evaluate if their combined genotype may be a better predictor of toxicity.

No significant financial relationships to disclose.

Multiplex tetra-primer amplification refractory mutation system PCR to detect 6 common germline mutations of the MUTYH gene associated with polyposis and colorectal cancer

BACKGROUND

We describe a simple tetra-primer amplification refractory mutation system PCR (T-ARMS-PCR) for detecting MUTYH mutations, which are associated with colorectal adenomas and colorectal cancer.

METHODS

We designed specific T-ARMS-PCR assays for 6 mutations (Y165C, G382D, 1395_7delGGA, Y90X, 1103delC, and R231H) selected on the basis of the frequency of their occurrence. We also designed a set of 3 multiplex T-ARMS PCR assays, each for detection of 2 mutations. We tested DNA samples from patients with attenuated or classic adenomatous polyposis coli and no detectable APC germline mutations.

RESULTS

All mutations were easily detected with both the specific and multiplex T-ARMS-PCR assays. Results were confirmed by DNA HPLC analysis in all 54 patients, and each mutation was confirmed by direct DNA sequencing.

CONCLUSIONS

T-ARMS-PCR does not require any special equipment, and it provides rapid, reproducible, and cost-effective detection of common MUTYH mutations. Multiplex T-ARMS-PCR allows the detection of 6 common MUTYH mutations with use of as few as 3 single tube PCR reactions. It could be useful to carry out large population-based epidemiologic studies.

A quantitative measurement of the human somatic mutation rate

The mutation rate (mu) is a key biological feature of somatic cells that determines risk for malignant transformation, and it has been exceedingly difficult to measure in human cells. For this purpose, a potential sentinel is the X-linked PIG-A gene, because its inactivation causes lack of glycosylphosphatidylinositol-linked membrane proteins. We previously found that the frequency (f) of PIG-A mutant cells can be measured accurately by flow cytometry, even when f is very low. Here we measure both f and mu by culturing B-lymphoblastoid cell lines and first eliminating preexisting PIG-A mutants by flow sorting. After expansion in culture, the frequency of new mutants is determined by flow cytometry using antibodies specific for glycosylphosphatidylinositol-linked proteins (e.g., CD48, CD55, and CD59). The mutation rate is then calculated by the formula mu = f/d, where d is the number of cell divisions occurring in culture. The mean mu in cells from normal donors was 10.6 x 10(-7) mutations per cell division (range 2.4 to 29.6 x 10(-7)). The mean mu was elevated >30-fold in cells from patients with Fanconi anemia (P < 0.0001), and mu varied widely in ataxia-telangiectasia with a mean 4-fold elevation (P = 0.002). In contrast, mu was not significantly different from normal in cells from patients with Nijmegen breakage syndrome. Differences in mu could not be attributed to variations in plating efficiency. The mutation rate in man can now be measured routinely in B-lymphoblastoid cell lines, and it is elevated in cancer predisposition syndromes. This system should be useful in evaluating cancer risk and in the design of preventive strategies.

Patients with paroxysmal nocturnal hemoglobinuria have a high frequency of peripheral-blood T cells expressing activating isoforms of inhibiting superfamily receptors

Patients with paroxysmal nocturnal hemoglobinuria (PNH) have a large clonal population of blood cells deriving from hematopoietic stem cells (HSCs) deficient in glycosylphosphatidylinositol (GPI)-anchored surface molecules. A current model postulates that PNH arises through negative selection against normal HSCs exerted by autoreactive T cells, whereas PNH HSCs escape damage. We have investigated the inhibitory receptor superfamily (IRS) system in 13 patients with PNH. We found a slight increase in the proportion of T cells expressing IRS. In contrast to what applies to healthy donors, the engagement of IRS molecules on T cells from patients with PNH elicited a powerful cytolytic activity in a redirected killing assay, indicating that these IRSs belong to the activating type. This was confirmed by clonal analysis: 50% of IRS+ T-cell clones in patients with PNH were of the activating type, while only 5% were of the activating type in healthy donors. Moreover, the ligation of IRS induces (1) production of tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) and (2) brisk cytolytic activity against cells bearing appropriate IRS counter-ligands. In addition, these IRS+ T cells show natural killer (NK)-like cytolytic activity to which GPI- cells were less sensitive than GPI+ cells. Thus, T cells with NK-like features, expressing the activating isoforms of IRS, may include effector cells involved in the pathogenesis of PNH.

In vivo gene marking of rhesus macaque long-term repopulating hematopoietic cells using a VSV-G pseudotyped versus amphotropic oncoretroviral vector

BACKGROUND

Gene transfer efficiency into primitive hematopoietic cells may be limited by their expression of surface receptors allowing vector entry. Vectors pseudotyped with the vesicular stomatitis virus (VSV-G) envelope do not need receptors to enter cells, and therefore may provide superior transduction efficiency.

METHODS

Using a competitive repopulation model in the rhesus macaque, we examined in vivo gene marking levels of blood cells transduced with two vectors: (i) a VSV-G pseudotyped retrovirus and (ii) a conventional amphotropic retrovirus. The VSV-G vector, containing the human glucose-6-phosphate dehydrogenase (G6PD) gene, was constructed for treatment of severe hemolytic anemia caused by G6PD deficiency. Three myeloablated animals were transplanted with peripheral blood CD34+ cells, half of which were transduced with the VSV-G vector and the other half with the amphotropic vector.

RESULTS

In all animals post-transplantation, levels of in vivo marking in circulating granulocytes and mononuclear cells were similar: 1% or less with both vectors. In one animal, the human G6PD enzyme transferred by the VSV-G vector was expressed in erythrocytes, early after transplantation, at a level of 45% of the endogenous rhesus G6PD protein.

CONCLUSIONS

In a clinically relevant animal model, we found similar in vivo marking with a VSV-G pseudotyped and a standard amphotropic oncoretroviral vector. Amphotropic receptor expression may not be a limiting factor in transduction efficiency, but VSV-G pseudotypes possess other practical advantages that may make them advantageous for clinical use.

CD157 is an important mediator of neutrophil adhesion and migration

CD157, a glycosylphosphatidylinositol (GPI)-anchored protein encoded by a member of the CD38 NADase/ADP-ribosyl cyclase gene family, is expressed on the surface of most human circulating neutrophils. This work demonstrates that CD157 is a receptor that induces reorganization of the cytoskeleton and significant changes in cell shape, and that signals mediated by CD157 act through modulation of cytosolic Ca(2+) concentration. These signals are independent of the products of CD157's enzymatic activities (ie, cyclic adenosine diphosphate [ADP]-ribose and ADP-ribose). Indeed, the enzymatic activities of CD157 in circulating neutrophils as well as in dimethyl sulfoxide (DMSO)-differentiated (CD157(+)/CD38(-)) HL-60 cells, are hardly detectable. This work also shows that the receptorial activity relies on cross-talk between CD157 and beta(2) integrin. CD157 localizes in GM1-enriched lipid rafts and, upon activation, it migrates to the uropod, a structure specialized in motility and adhesive functions. Indeed, CD157 is involved in adhesion to extracellular matrix proteins and in chemotaxis induced in vitro by formyl-methionyl-leucyl-phenylalanine (fMLP). These findings were consistent with the results obtained in neutrophils from patients with paroxysmal nocturnal hemoglobinuria (PNH), in which CD157 is deficient. These neutrophils showed constant defects in adhesion and migration. Our data attribute specific and crucial roles to CD157 in the regulation of innate immunity during inflammation.

G6PD is indispensable for erythropoiesis after the embryonic-adult hemoglobin switch

Glucose 6-phosphate dehydrogenase (G6PD) (EC 1.1.1.42) is an essential enzyme for the rapid production of NADPH, as required on exposure to oxidative stress. Mouse embryonic stem (ES) cells can produce all embryonic and fetal/adult cell types. By studying the in vitro differentiation of embryoid bodies produced from G6pdDelta ES cells that are totally unable to produce G6PD protein, we found that these cells are able to differentiate into mesodermal cells, cardiomyocytes, hepatocytes, and primitive erythroid cells. However, we show here that, after the hemoglobin switch has taken place, definitive erythrocytes die by apoptosis. This apoptotic death is delayed by reducing agents and by a caspase inhibitor, but it is prevented only by the restoration of G6PD activity. Thus, G6PD proves indispensable for definitive erythropoiesis.

Severe telomere shortening in patients with paroxysmal nocturnal hemoglobinuria affects both GPI- and GPI+ hematopoiesis

A most distinctive feature of paroxysmal nocturnal hemoglobinuria (PNH) is that in each patient glycosylphosphatidylinositol-negative (GPI-) and GPI+ hematopoietic stem cells (HSCs) coexist, and both contribute to hematopoiesis. Telomere size correlates inversely with the cell division history of HSCs. In 10 patients with hemolytic PNH the telomeres in sorted GPI- granulocytes were shorter than in sorted GPI+ granulocytes in 4 cases, comparable in 2 cases, and longer in the remaining 4 cases. Furthermore, the telomeres of both GPI- and GPI+ hematopoietic cells were markedly shortened compared with age-matched controls. The short telomeres in the GPI- cells probably reflect the large number of cell divisions required for the progeny of a single cell to contribute a large proportion of hematopoiesis. The short telomeres of the GPI+ cells indicate that the residual hematopoiesis contributed by these cells is not normal. This epigenetic change is an additional feature shared by PNH and aplastic anemia.