Blood consult: paroxysmal nocturnal hemoglobinuria and its complications

Interaction between Herpes Virus Infections and IL10 and Risk of Bone Marrow Suppression

BACKGROUND

Syndrome of transient bone marrow suppression may result from various extra-hematological diseases, such as immunological deregulations, and viral infectious diseases secondarily affecting the function of hematopoietic stem cells.

OBJECTIVE

To evaluate the pathogenic role of herpes viruses and their contraction with IL10 cytokine gene polymorphism, which can impair hematopoiesis in patients with transient bone marrow suppression.

METHODS

In a cross-sectional study 30 patients who admitted to Namazi Hospital, affiliated to Shiraz University of Medical Sciences, with transient bone marrow suppression were recruited. Diagnosis of the transient bone marrow suppression was made by expert hematologists. A control group consisting of 100 healthy unrelated individuals was also included. One EDTA-treated blood sample was collected from each studied patients and plasma was isolated. The molecular prevalence of cytomegalovirus and HHV8 evaluated was evaluated using real-time and nested PCR protocols, respectively. The SNPs of the IL10 (rs 1800896-1082G/A) cytokine gene was evaluated by PCR-RFLP method.

RESULTS

Cytomegalovirus and HHV8 infections were found in 2 and 3 of studied patients with transient bone marrow suppression. Significant higher frequency of IL10 G allele and GG genotype were found in HHV8-infected patients comparing to uninfected ones. Higher frequencies of A allele and AG and AA genotypes of IL10 were found in cytomegalovirus-uninfected patients comparing to infected ones, respectively. The significant higher frequencies of IL10 AA and AG genotypes were found in controls compared to bone marrow suppressed patients.

CONCLUSION

IL10 genetic polymorphism might have determinative role in resistance to the cytomegalovirus, especially HHV8 infections, in patients with bone marrow suppression. Focus in new interaction between HHV8 infection and IL10 genetics in bone marrow suppressed patients should be completed by the analysis of the anti-herpes virus immunity in future studies.

Eculizumab in the management of paroxysmal nocturnal hemoglobinuria: patient selection and special considerations

Paroxysmal nocturnal hemoglobinuria (PNH) is a nonmalignant clonal disorder resulting from somatic mutation in the PIG-A gene leading to a deficiency of the membrane-anchoring molecule glycosylphosphatidylinositol. The lack of expression of two glycosylphosphatidylinositol-anchored proteins involved in the regulation of the complement system renders PNH erythrocytes susceptible to complement-mediated lysis. Clinical manifestations include thromboembolic disease, chronic kidney injury, pulmonary hypertension, smooth muscle dysfunction, and chronic hemolysis. Until recently, treatment was mainly supportive with most patients suffering from significant morbidity and shortened survival compared to age-matched controls. The development of eculizumab, a humanized monoclonal antibody directed against the terminal complement protein C5, has resulted in dramatic improvements of survival and reduction in complications. In this paper, we review some special considerations pertaining to the use of eculizumab for PNH.

Successful pregnancy outcome in paroxysmal nocturnal hemoglobinuria (PNH) following escalated eculizumab dosing to control breakthrough hemolysis

Pregnancy in women with paroxysmal nocturnal hemoglobinuria (PNH) is associated with increased maternal and fetal morbidity and mortality. There is limited published experience regarding therapy of PNH during pregnancy. We describe a case of a 30 year old female with hypoplastic myelodysplastic syndrome and PNH. After two years of treatment with eculizumab, she became pregnant. She developed breakthrough hemolysis at 20 weeks gestation. Pharmacokinetic and pharmacodynamic studies demonstrated a subtherapeutic eculizumab level with absence of complement blockade. Escalation of her eculizumab dose successfully controlled hemolysis and restored therapeutic eculizumab level and activity. She delivered a healthy baby at 36 weeks.

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Pregnancy in PNH cause increased maternal and fetal morbidity & mortality.

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Limited published data regarding the use of eculizumab in pregnancy.

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Breakthrough hemolysis in pregnancy despite standard eculizumab administration.

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Escalated dose of eculizumab is required to achieve therapeutic eculizumab levels.

TNF-α -308 G>A polymorphism and risk of bone marrow failure syndrome: A meta-analysis

The influence of the TNF-α -308 G>A polymorphism on bone marrow failure syndrome susceptibility is unclear. We have conducted a meta-analysis of all relevant published studies. We searched PubMed, Chinese Biomedical Literature and China National Knowledge Infrastructure databases up to February 2015. Odds ratios (ORs) with 95% confidence intervals (CIs) were applied to assess the strength of associations. Eleven case-control studies with a total sample size of 909 cases and 1803 controls were eligible to assess the association between the TNF-α -308 G>A polymorphism and susceptibility to bone marrow failure syndrome. Overall, the TNF-α -308 G>A polymorphism was significantly associated with an increased risk of bone marrow failure syndrome in any genetic model. In stratified analysis by disease type, there was a significant association between the TNF-α -308 G>A polymorphism and increased risk of aplastic anemia but no significant association with myelodysplastic syndrome (AA vs. GG: OR=2.23, 95% CI=1.23-4.05, P=0.006; recessive model: OR=3.52, 95% CI=1.30-9.53, P=0.010). In subgroup analysis by ethnicity, there were significant associations between the TNF-α -308 G>A polymorphism and increased risk of bone marrow failure syndrome for Caucasians in two models, but not in Asian populations (AA vs. GG: OR=2.66, 95% CI=1.36-5.21, P=0.003; recessive model: OR=2.68, 95% CI=1.37-5.24, P=0.002). In conclusion, our meta-analysis suggests that the TNF-α -308 G>A polymorphism may contribute to the risk of bone marrow failure syndrome, particularly among Caucasian and aplastic anemia patients. Further investigations are needed to clarify the role of the TNF-α -308 G>A polymorphism in bone marrow failure syndrome.

Paroxysmal nocturnal hemoglobinuria: a complement-mediated hemolytic anemia

Paroxysmal nocturnal hemoglobinuria is manifests with a chronic hemolytic anemia from uncontrolled complement activation, a propensity for thrombosis and marrow failure. The hemolysis is largely mediated by the alternative pathway of complement. Clinical manifestations result from the lack of specific cell surface proteins, CD55 and CD59, on PNH cells. Complement inhibition by eculizumab leads to dramatic clinical improvement. While this therapeutic approach is effective, there is residual complement activity resulting from specific clinical scenarios as well as from upstream complement components that can account for suboptimal responses in some patients. Complement inhibition strategies are an area of active research.