Pulmonary hypertension in hemolytic anemias

Clinical challenges in the treatment of a patient with decompensated heart failure and glucose-6-phosphate dehydrogenase deficiency (G6PDd)

We present a case of a man in his 60s, known with glucose-6-phosphate dehydrogenase deficiency (G6PDd) and cor pulmonale, admitted to the department of cardiology due to cardiac decompensation and anaemia. The main complaint was dyspnoea. Echocardiography confirmed severe cor pulmonale with compression of the left ventricle. G6PDd has been linked with pulmonary hypertension which could contribute to aforementioned echocardiographic findings. Diuretics are the first line of treatment when it comes to cardiac decompensation, but sulfonamide diuretics can induce or exacerbate haemolysis in patients with G6PDd. Due to the respiratory distress of the patient, a treatment plan including sulfonamide diuretics was initiated in collaboration with the haematologists. Unfortunately, the patient died 2 days after admission. This case emphasises that not all cardiac patients can tolerate standard treatment with sulfonamide diuretics; despite this, they remain essential in the acute setting, and they are associated with foreseeable but only partly manageable complications in susceptible patients.

Heme: The Lord of the Iron Ring

Heme is an iron-protoporphyrin complex with an essential physiologic function for all cells, especially for those in which heme is a key prosthetic group of proteins such as hemoglobin, myoglobin, and cytochromes of the mitochondria. However, it is also known that heme can participate in pro-oxidant and pro-inflammatory responses, leading to cytotoxicity in various tissues and organs such as the kidney, brain, heart, liver, and in immune cells. Indeed, heme, released as a result of tissue damage, can stimulate local and remote inflammatory reactions. These can initiate innate immune responses that, if left uncontrolled, can compound primary injuries and promote organ failure. In contrast, a cadre of heme receptors are arrayed on the plasma membrane that is designed either for heme import into the cell, or for the purpose of activating specific signaling pathways. Thus, free heme can serve either as a deleterious molecule, or one that can traffic and initiate highly specific cellular responses that are teleologically important for survival. Herein, we review heme metabolism and signaling pathways, including heme synthesis, degradation, and scavenging. We will focus on trauma and inflammatory diseases, including traumatic brain injury, trauma-related sepsis, cancer, and cardiovascular diseases where current work suggests that heme may be most important.

Novel Compound Heterozygous PKLR Mutation Induced Pyruvate Kinase Deficiency With Persistent Pulmonary Hypertension in a Neonate: A Case Report

Background

Pulmonary hypertension could be associated with pyruvate kinase deficiency (PKD). There are few reported cases of PPHN as the first clinical manifestation of PKD. Herein we report a rare case of PKD in which the patient exhibited persistent pulmonary hypertension in the neonate (PPHN), and genetic testing helped to rapidly identify an potential association.

Case presentation

The patient was a newborn boy who suffered from severe dyspnea, extreme anemia, skin pallor, and hypoxemia. Repeated echocardiography indicated persistent severe pulmonary hypertension with a calculated pulmonary artery pressure of 75 mmHg, and right ventricular hypertrophy. The administration of nitric oxide significantly reduced the pulmonary artery pressure. Whole-exome sequencing revealed a compound heterozygous mutation consisting of c.707T > G and c.826_827insAGGAGCATGGGG. PolyPhen_2 and MutationTaster indicated that both the c.707T > G (probability 0.999) and c.826_827insAGGAGCATGGGG (probability 0.998) mutations were disease causing. PROVEAN protein batch analysis indicated that the associated p.L236R region was deleterious (score −4.71) and damaging (SIFT prediction 0.00), and this was also the case for p.G275_V276insEEHG (deleterious score −12.00, SIFT prediction 0.00). Substantial structural changes in the transport domain of the protein were predicted using SWISS-MODEL, and indicated that both mutations led to an unstable protein structure. Thus, a novel compound heterozygous mutation of PKLR-induced PKD with PPHN was diagnosed.

Conclusion

The current study suggests that molecular genetic screening is useful for identifying PPHN, particularly in children with metabolic disorders. In patients exhibiting unexplained hyperbilirubinemia combined with severe pulmonary hypertension, PKD might be a potential possible alternative explanation. Genetic screening is helpful for identifying genetic causes of pulmonary hypertension, especially in patients with PPHN. This report expands the mutation spectrum of the PKLR gene, and contributes to the genotype-phenotype map of PKD.

Heme stimulates platelet mitochondrial oxidant production to induce targeted granule secretion

Hemolysis, a pathological component of many diseases, is associated with thrombosis and vascular dysfunction. Hemolytic products, including cell-free hemoglobin and free heme directly activate platelets. However, the effect of hemolysis on platelet degranulation, a central process in not only thrombosis, but also inflammatory and mitogenic signaling, remains less clear. Our group showed that hemoglobin-induced platelet activation involved the production of mitochondrial reactive oxygen species (mtROS). However, the molecular mechanism by which extracellular hemolysis induces platelet mtROS production, and whether these mtROS regulate platelet degranulation remains unknown. Here, we demonstrate using isolated human platelets that cell free heme is a more potent agonist for platelet activation than hemoglobin, and stimulates the release of a specific set of molecules, including the glycoprotein thrombospondin-1 (TSP-1), from the α-granule of platelets. We uncover the mechanism of heme-mediated platelet mtROS production which is dependent on the activation of platelet toll-like receptor 4 (TLR4) signaling and leads to the downstream phosphorylation and inhibition of complex-V by the serine kinase Akt. Notably, inhibition of platelet TLR4 or Akt, or scavenging of mtROS prevents heme-induced granule release in vitro. Further, heme-dependent granule release is significantly attenuated in vivo in mice lacking TLR4 or those treated with the mtROS scavenger MitoTEMPO. These data elucidate a novel mechanism of TLR4-mediated mitochondrial regulation, establish the mechanistic link between hemolysis and platelet degranulation, and begin to define the heme and mtROS-dependent platelet secretome. These data have implications for hemolysis-induced thrombo-inflammatory signaling and for the consideration of platelet mitochondria as a therapeutic target in hemolytic disorders.

Hemolysis-induced Lung Vascular Leakage Contributes to the Development of Pulmonary Hypertension

Although hemolytic anemia-associated pulmonary hypertension (PH) and pulmonary arterial hypertension (PAH) are more common than the prevalence of idiopathic PAH alone, the role of hemolysis in the development of PAH is poorly characterized. We hypothesized that hemolysis independently contributes to PAH pathogenesis via endothelial barrier dysfunction with resulting perivascular edema and inflammation. Plasma samples from patients with and without PAH (both confirmed by right heart catheterization) were used to measure free hemoglobin (Hb) and its correlation with PAH severity. A sugen (50 mg/kg)/hypoxia (3 wk)/normoxia (2 wk) rat model was used to elucidate the role of free Hb/heme pathways in PAH. Human lung microvascular endothelial cells were used to study heme-mediated endothelial barrier effects. Our data indicate that patients with PAH have increased levels of free Hb in plasma that correlate with PAH severity. There is also a significant accumulation of free Hb and depletion of haptoglobin in the rat model. In rats, perivascular edema was observed at early time points concomitant with increased infiltration of inflammatory cells. Heme-induced endothelial permeability in human lung microvascular endothelial cells involved activation of the p38/HSP27 pathway. Indeed, the rat model also exhibited increased activation of p38/HSP27 during the initial phase of PH. Surprisingly, despite the increased levels of hemolysis and heme-mediated signaling, there was no heme oxygenase-1 activation. This can be explained by observed destabilization of HIF-1a during the first 2 weeks of PH regardless of hypoxic conditions. Our data suggest that hemolysis may play a significant role in PAH pathobiology.

A comparative cross-sectional study of some hematological parameters of hypertensive and normotensive individuals at the university of Gondar hospital, Northwest Ethiopia

Background

Hypertension is a major health problem worldwide. It can lead to cardiovascular disease and also leads to functional disturbances including hematological parameters. The abnormalities of haematological parameters may enhance an end-organ damage. Therefore, the aim of this study was to assess some hematological parameters of hypertensive individuals in comparison with normotensive individuals at University of Gondar hospital, northwest Ethiopia.

Methods

A cross sectional comparative study was conducted from October to November 2015 on a total of 126 hypertensive and 126 normotensive individuals at University of Gondar Hospital. All participants after taking informed consent were interviewed for detailed history and 3 ml of blood was collected for hematological test analysis. Independent t-test and the Mann Whitney u-test were used to find out significant difference and Pearson’s and Spearman’s correlation were used for correlation test. P values less than 0.05 was considered the level of significance.

Result

From a total of 252 study subjects, about 67.5% were females. The mean age of study subjects was 50.3 ± 11 years for hypertensive individuals and 49.8 ± 11.6 years for normotensive individuals with range of 18–65 years. In the present study, the median (IQR) value of WBC, RBC, Hgb, HCT, MCV and the mean value of MCHC, RDW, MPV and PDW were significantly higher in hypertensive group compared to apparently healthy normotensive groups. Additionally, WBC, RBC, Hgb, HCT and PLT showed statistically significant positive correlations with blood pressure indices. Platelet count and MCH did not show statistically significant difference between the two groups.

Conclusion

Hypertension has impact on hematological parameters. In this study, the mean and median values of haematological parameters in hypertensive individuals were significantly different compared to apparently healthy normotensive individuals. Hence, hematological parameters can be used to monitor the prognosis of the disease and manage hypertensive related complications, and it is important to assess hematological parameters for hypertensive individuals which may help to prevent complications associated hematological disorders.

Electronic supplementary material

The online version of this article (doi: 10.1186/s12878-017-0093-9) contains supplementary material, which is available to authorized users.

Modulatory effects of melatonin and vitamin C on oxidative stress-mediated haemolytic anaemia and associated cardiovascular dysfunctions in rats

Background Phenylhydrazine (PHE) in experimental animal models has been widely reported to cause haemolytic anaemia, via the induction of oxidative stress and thus causing deleterious cardiovascular complications. Hence, this study was designed to evaluate the possible modulatory role of melatonin (MLT) or vitamin C when co-administered with PHE. Methods Anaemia was established with PHE administration. MLT or vitamin C was co-administered with PHE. Haematological parameters, markers of oxidative stress, enzymic and non-enzymic antioxidants, blood pressure and electrocardiograms were assessed. Results PHE administration led to a significant (p<0.05) increase in malondialdehyde (MDA), and hydrogen peroxide (H2O2) generated in cardiac, renal and red blood cell (RBC) lysates. PHE also significantly reduced the activity of glutathione peroxidase (GPx), superoxide dismutase (SOD) and reduced glutathione (GSH) contents, respectively. The RBC counts, haemoglobin (Hb) concentration and packed cell volume (PCV) were also significantly reduced following the administration of PHE. Furthermore, the systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MABP) increased significantly in rats administered PHE alone. Similarly, PHE administration led to a significant drop in heart rate but prolonged QRS, QT and QTc interval. Pathology of the heart and kidney was also observed in PHE treated group. However, treatment with MLT and vitamin C improved enzymic and non-enzymic antioxidant system together with the restoration of SBP, DBP and MABP to near normal. The architectural anarchy observed in the heart and kidney of PHE administered rats was reversed to some extent. Conclusions Hence, MLT and vitamin C could be employed as therapeutic targets in various cardiovascular diseases and its complications.

Adding insult to injury: autoimmune haemolytic anaemia complicated by pulmonary embolism

Autoimmune haemolytic anaemia (AIHA) is a disease characterised by the production of pathological antibodies that attach to the surface of a patient's own red blood cells, resulting in haemolysis. It can present in either an acute or a chronic manner. In addition to the obvious consequence of anaemia, there are other potentially deadly complications that can arise from AIHA, such as venous thromboembolism (VTE) and pulmonary hypertension. We report a case of a 52-year-old woman who developed a pulmonary embolism (PE) soon after being diagnosed with AIHA. Despite having a very small pulmonary venous clot burden, she developed profound haemodynamic compromise with severe right ventricular dysfunction, which quickly reversed with inhaled nitric oxide treatment. This case makes an interesting observation of cell-free haemoglobin-associated nitric oxide scavenging as a mechanism of pulmonary hypertension and highlights the possible benefit of nitric oxide in treatment.

Pulmonary arterial hypertension in pediatric patients with hematopoietic stem cell transplant-associated thrombotic microangiopathy

Pulmonary arterial hypertension (PAH) is rarely included in the differential diagnosis of cardiorespiratory failure after pediatric hematopoietic stem cell transplant (HSCT) as the clinical presentation is nonspecific and may mimic other etiologies. The pathogenesis of PAH in HSCT is poorly understood and the diagnosis requires a high degree of suspicion. We describe 5 children diagnosed with PAH after allogeneic HSCT. All 5 patients had prolonged clinical signs of transplantation-associated thrombotic microangiopathy (TA-TMA) when they presented with hypoxemic respiratory failure and evidence of PAH. Four of the 5 patients had echocardiographic evidence of PAH, and 1 patient was diagnosed with PAH only on autopsy. PAH was diagnosed a median of 76 days (range, 56-101 days) after a diagnosis of TA-TMA. Despite aggressive medical management, including inhaled nitric oxide, 4 of the 5 patients died. One patient recovered from PAH after 11 months of sildenafil therapy. Three of the 4 deceased patients had an autopsy performed, demonstrating severe pulmonary vascular disease consistent with TA-TMA and severe PAH. We conclude that TA-TMA can be associated with significant pulmonary vascular injury presenting as hypoxemic respiratory failure with PAH after HSCT. Pediatric patients with unexplained hypoxemia after HSCT should be evaluated for both transplantation complications, TA-TMA and PAH, accordingly.

Effect of vasodilators in patient with pulmonary hypertension associated with hemolytic anemia

Pulmonary arterial hypertension (PAH) has been described to associate with hemolytic anemia in updated clinical classification of pulmonary hypertension. A 56-year-old woman, diagnosed with warm antibody autoimmune hemolytic anemia (AIHA), was treated with oral corticosteroids at the Department of Hematology, Osaka University Hospital for 30 years. Her AIHA worsened 3 months before the admission, and she was treated with rituximab and cyclosporine in combination with prednisolone. Soon after she left the hospital, she developed dyspnea on effort and leg edema, therefore she was re-admitted to the Department of Cardiovascular Medicine. Echocardiogram and cardiac catheterization demonstrated PAH associated with AIHA. She was treated with three types of vasodilatory agents, resulting in an improvement in pulmonary arterial pressure and pulmonary vascular resistance after 6 weeks. A few weeks after she left the hospital, her hemolytic anemia became in remission without intensifying AIHA therapy, and did not worsen for a year of follow-up. Although corticosteroids are the first-line treatment for AIHA, medications for PAH should be considered when the first-line therapy for AIHA failed to improve PAH.