Infections and thalassaemia

Survival and causes of death in patients with alpha and beta-thalassemia in Northern Thailand

BACKGROUND

Thalassemia is the most prevalent hereditary anaemia worldwide. Severe forms of thalassemia can lead to reduced life expectancy due to disease-related complications.

OBJECTIVES

To investigate the survival of thalassemia patients across varying disease severity, causes of death and related clinical factors.

PATIENTS AND METHODS

We conducted a retrospective review of thalassemia patients who received medical care at Chiang Mai University Hospital. The analysis focused on survival outcomes, and potential associations between clinical factors and patient survival.

RESULTS

A total of 789 patients were included in our study cohort. Among them, 38.1% had Hb H disease, 35.4% had Hb E/beta-thalassemia and 26.5% had beta-thalassemia major. Half of the patients (50.1%) required regular transfusions. Sixty-five patients (8.2%) had deceased. The predominant causes of mortality were infection-related (36.9%) and cardiac complications (27.7%). Transfusion-dependent thalassemia (TDT) (adjusted HR 3.68, 95% CI 1.39-9.72, p = 0.008) and a mean serum ferritin level ≥3000 ng/mL (adjusted HR 4.18, 95% CI 2.20-7.92, p < 0.001) were independently associated with poorer survival.

CONCLUSIONS

Our study highlights the primary contributors to mortality in patients with thalassemia as infection-related issues and cardiac complications. It also underscores the significant impact of TDT and elevated serum ferritin levels on the survival of thalassemia patients.

Knowledge, attitude and acceptance regarding bone marrow transplantation in caregivers of beta-thalassemia major patients

OBJECTIVE

Knowledge, Attitude, and Acceptance regarding Bone marrow transplantation in caregivers of beta-thalassemia major patients.

METHODS

A cross-sectional study was conducted among the caregivers of pediatric patients with betathalassemia major in blood transfusion centres in Bangalore, India. Their knowledge, attitude, and acceptance regarding bone marrow transplantation were assessed using a validated questionnaire. The study aimed to identify factors that influence caregivers' decision about bone marrow transplantation.

RESULTS

The knowledge, attitude, and acceptance of the caregivers towards bone marrow transplantation are shown to depend on gender, education and socio-economic status. The results of this study reveal that male caregivers generally exhibited higher levels of knowledge and had a better attitude towards it as compared to their female counterparts. Higher education and socio-economic status were associated with better knowledge, more favourable attitudes and a higher acceptance towards the procedure.

Neutrophil Diversity (Immature, Aged, and Low-Density Neutrophils) and Functional Plasticity: Possible Impacts of Iron Overload in β-Thalassemia

Neutrophil dysfunction is a form of immune suppression in patients with β-thalassemia (Beta-thal), although data on this are limited. In this study, blood from patients and healthy volunteers was analyzed. Flow cytometry analysis demonstrated an increase in immature neutrophils (CD16- CD62L+) and aged (senescent) neutrophils (CD16+ CD62L-) in Beta-thal patients compared to healthy volunteers. The Beta-thal neutrophils demonstrated less prominent chemotaxis and phagocytosis than healthy neutrophils at the baseline. With phorbol myristate acetate (PMA) or lipopolysaccharide (LPS) stimulations, some of the indicators, including the flow cytometry markers (CD11b, CD62L, CD66b, CD63, apoptosis, and reactive oxygen species) and neutrophil extracellular traps (NETs; detected by anti-citrullinated histone 3 immunofluorescence), were lower than the control. Additionally, low-density neutrophils (LDNs), which are found in the peripheral blood mononuclear cell (PBMC) fraction, were observed in Beta-thal patients but not in the control group. The expression of CD11b, CD66b, CD63, arginase I, and ROS in LDNs was higher than the regular normal-density neutrophils (NDNs). The proliferation rate of CD3+ T cells isolated from the PBMC fraction of healthy volunteers was higher than that of the cells from patients with Beta-thal. The incubation of red blood cell (RBC) lysate plus ferric ions with healthy NDNs transformed the NDNs into the aged neutrophils (decreased CD62L) and LDNs. In conclusion, iron overload induces neutrophil diversity along with some dysfunctions.

Hypoferremia of inflammation: Innate host defense against infections

Iron is an essential nutrient for microbes, plants and animals. Multicellular organisms have evolved multiple strategies to control invading microbes by restricting microbial access to iron. Hypoferremia of inflammation is a rapidly-acting organismal response that prevents the formation of iron species that would be readily accessible to microbes. This review takes an evolutionary perspective to explore the mechanisms and host defense function of hypoferremia of inflammation and its clinical implications.

Understanding How Minerals Contribute to Optimal Immune Function

Sufficient mineral supply is vital not only for the innate immune system but also for the components of the adaptive immune defense, which encompass defense mechanisms against pathogens and the delicate balance of pro- and anti-inflammatory regulation in the long term. Generally, a well-balanced diet is capable of providing the necessary minerals to support the immune system. Nevertheless, specific vulnerable populations should be cautious about obtaining adequate amounts of minerals such as magnesium, zinc, copper, iron, and selenium. Inadequate levels of these minerals can temporarily impair immune competence and disrupt the long-term regulation of systemic inflammation. Therefore, comprehending the mechanisms and sources of these minerals is crucial. In exceptional circumstances, mineral deficiencies may necessitate supplementation; however, excessive intake of supplements can have adverse effects on the immune system and should be avoided. Consequently, any supplementation should be approved by medical professionals and administered in recommended doses. This review emphasizes the crucial significance of minerals in promoting optimal functioning of the immune system. It investigates the indispensable minerals required for immune system function and the regulation of inflammation. Moreover, it delves into the significance of maintaining an optimized intake of minerals from a nutritional standpoint.

Extensive systemic thrombo-embolism including intra-cardiac thrombosis mimicking an atrial myxoma in a patient with beta thalassaemia major - a case report

BACKGROUND

Sepsis and thrombo-embolic disease are well known complications of thalassemia major. Intracardiac thrombi are however rare and can lead to diagnostic dilemmas.

CASE PRESENTATION

We report the case of a 20-year-old female splenectomised thalassaemia major patient with severe iron overload, who presented with life threatening sepsis associated with a liver abscess. Discovery of a large oscillating intra cardiac lesion on 2D echocardiogram confirmed by Contrast Enhanced Computed Tomography (CECT) chest in the right atrium extending from the left hepatic vein through the inferior vena cava complicated the clinical course. After a prolonged Intensive Care Unit (ICU) stay supported with antibiotics and anticoagulation, she recovered with evidence of resolution of the intra cardiac thrombus.

CONCLUSIONS

Early recognition and prompt aggressive treatment of sepsis in patients with thalassemia is essential to prevent complications. Intracardiac thrombosis is a potentially treatable cause for an intra cardiac mass in patients with thalassemia major, which should not be missed.

Analysis of Hematological Indices and Splenectomy Rates in 2,130 Patients with Hemoglobin H Diseases or β-Thalassemia

INTRODUCTION

Splenomegaly and hypersplenism are common complications of thalassemia patients due to the excessive clearance of defective red blood cells from the spleen. To date, splenectomy has been considered one of the most effective treatments for splenomegaly, reducing clinical severity among thalassemia patients. Thus, we aim to investigate the differences in splenectomy rates and hematological indices among thalassemia patients with different genotypes.

METHOD

In this study, we analyzed the clinical data of thalassemia in 2,130 patients admitted to the 923rd Hospital of the People's Liberation Army from January 2006 to December 2020, and the statistical software SPSS 26.0 was applied to analyze the data.

RESULT

Of the 2,130 patients with thalassemia, 265 patients underwent splenectomy. It was determined that significantly more patients with hemoglobin H (HbH) disease, a form of α-thalassemia, have undergone splenectomy than β-thalassemia patients (20% vs. 7%). Further, HbH disease patients were diagnosed at a significantly older age than β-thalassemia patients.

CONCLUSION

The greater probability of HbH disease patients undergoing splenectomy is likely influenced by multiple factors, including their lower dependency on transfusion, leading to high spleen compensatory stress on the spleen, and the destruction of defective erythrocytes. In contrast, β-thalassemia is clinically more severe and less tolerant of hemoglobin fluctuations. Based on these findings, clinicians are suggested to pay more attention to HbH disease patients as many of them are still under-transfused, which could lead to chronic hemolysis and more severe hepatosplenomegaly. These results might offer insight for improving the clinical management of patients with different types of thalassemia.

Health-related quality of life among thalassemia patients in Bangladesh using the SF-36 questionnaire

Thalassemia is one of the most common autosomal recessive hereditary blood disorders worldwide, especially in developing countries, including Bangladesh. Thus, this study aimed to determine HRQoL and its determinants of thalassemia patients (TP) in Bangladesh. A cross-sectional survey was performed on 356 randomly selected thalassemia patients. Participants were invited to face-to-face interviews. Descriptive statistics (frequencies and percentages), independent t-test, ANOVA, and multivariate (linear and logistic regression) analysis was performed to analyze the data. Our demographic data showed that among 356 patients, 54% and 46% were male and female, respectively, with an average age of 19.75 (SD = 8.02) years. Most were transfusion-dependent (91%), 26% had comorbidities, and 52% were from low-income families. In the case of HRQoL, male patients showed significantly higher scores of bodily pains and physical health summaries than female patients. Lower income, high blood transfusion status, disease severity, comorbidities, and medical expenses (p < 0.05; CI 95%) are significantly associated with lower SF-36 scores. This study found an association between lower income, blood transfusion, disease severity, comorbidities, as well as medical expenses, and the deterioration of HRQoL among TP. Male patients experienced poorer HRQoL than females. National action plans are required to guarantee the holistic welfare of thalassemia patients.

Pathogenic Mechanisms in Thalassemia II: Iron Overload

Iron overload remains a lethal complication of β-thalassemia and other anemias caused by ineffective erythropoiesis. This review discusses the pathogenetic mechanisms of iron overload in thalassemia, at organismal, cellular, and molecular levels.

Intestinal barrier functions in hematologic and oncologic diseases

The intestinal barrier is a complex structure that not only regulates the influx of luminal contents into the systemic circulation but is also involved in immune, microbial, and metabolic homeostasis. Evidence implicating disruption in intestinal barrier functions in the development of many systemic diseases, ranging from non-alcoholic steatohepatitis to autism, or systemic complications of intestinal disorders has increased rapidly in recent years, raising the possibility of the intestinal barrier as a potential target for therapeutic intervention to alter the course and mitigate the complications associated with these diseases. In addition to the disease process being associated with a breach in the intestinal barrier functions, patients with hematologic and oncologic diseases are particularly at high risks for the development of increased intestinal permeability, due to the frequent use of broad-spectrum antibiotics and chemoradiation. They also face a distinct challenge of being intermittently severely neutropenic due to treatment of the underlying conditions. In this review, we will discuss how hematologic and oncologic diseases are associated with disruption in the intestinal barrier and highlight the complications associated with an increase in the intestinal permeability. We will explore methods to modulate the complication. To provide a background for our discussion, we will first examine the structure and appraise the methods of evaluation of the intestinal barrier.

The ultimate tradeoff: how red cell adaptations to malaria alter the host response during critical illness

The human immune system evolved in response to pathogens. Among these pathogens, malaria has proven to be one of the deadliest and has exerted the most potent selective pressures on its target cell, the red blood cell. Red blood cells have recently gained recognition for their immunomodulatory properties, yet how red cell adaptations contribute to the host response during critical illness remains understudied. This review will discuss how adaptations that may have been advantageous for host survival might influence immune responses in modern critical illness. We will highlight the current evidence for divergent host resilience arising from the adaptations to malaria and summarize how understanding evolutionary red cell adaptations to malaria may provide insight into the heterogeneity of the host response to critical illness, perhaps driving future precision medicine approaches to syndromes affecting the critically ill such as sepsis and acute respiratory distress syndrome (ARDS).

A comprehensive study of immune function and immunophenotyping of white blood cells from β-thalassaemia/HbE patients on hydroxyurea supports the safety of the drug

Hydroxyurea (HU) (hydroxycarbamide) is used as a therapeutic option in β-thalassaemia to increase fetal haemoglobin, which results in a reduced requirement for blood transfusion. However, a potential serious adverse effect of HU is neutropenia. Abnormal neutrophil maturation and function in β-thalassaemia/HbE patients are well documented. This raises questions about the effect of the drug with regards to the immune response these patients. This study investigated the effects of HU treatment on both innate and adaptive immunity in a cross-sectional study of 28 β-thalassaemia/HbE patients who had received HU treatment (BE+HU) as compared with 22 β-thalassaemia/HbE patients who had not received HU (BE-HU) and 26 normal subjects. The expression of PU.1 and C/EBPβ, transcription factors, which are associated with neutrophil maturation, was significantly reduced in BE+HU patients as compared with BE-HU patients and normal subjects. Interestingly, C3bR expression on neutrophils and their oxidative burst activity in BE+HU were restored to close to normal levels when compared with BE-HU. There was no observed effect of HU on monocytes, myeloid derived suppressor cells (both granulocytic and monocytic subsets), CD4⁺ T cells, CD8⁺ T cells, complement levels and serum immunoglobulin levels in this study. The full immunophenotyping analysis in this study indicates that HU therapy in β-thalassaemia/HbE patients does not significantly compromise the immune response.

Alteration of monocyte subsets and their functions in thalassemia patients

Infection is one of the leading causes of mortality in thalassemia patients. This study aimed to examine qualitative and quantitative changes in monocytes in thalassemia patients. Monocytes were isolated from peripheral blood mononuclear cells and separated into subpopulations by flow cytometry. Cytokine levels were measured using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and sandwich enzyme-linked immunosorbent assay (ELISA). The primary endpoint was monocyte-derived TNF-α expression. A total of 78 patients and 26 controls were included. The mean log (TNF-α fold-change) by qRT-PCR was significantly lower in all thalassemia groups, at 1.27 in controls, versus 0.97 (p = 0.0014) in non-transfusion-dependent thalassemia (NTDT), 0.96 (p = 0.0004) in non-splenectomized transfusion-dependent thalassemia (TDT-NS), and 0.87 (p < 0.0001) in splenectomized transfusion-dependent thalassemia (TDT-S). Similarly, the mean 2-h TNF-α level measured by sandwich ELISA assay was significantly lower in all thalassemia groups, at 98.16 pg/mL in controls, versus 56.45 pg/mL (p = 0.0093) in NTDT, 39.05 pg/mL (p = 0.0001) in TDT-NS and 32.37 pg/mL (p < 0.0001) in TDT-S. Likewise, TDT patients had a significantly decreased percentage of non-classical monocytes, by approximately half compared to controls. Our results show that thalassemia major patients have clearly impaired monocyte counts and function.

Role of iron in the treatment of sepsis

Iron is an important microelement in human and microbial life activities. During the pathophysiological process of sepsis, iron metabolism changes and the body undergoes a series of changes to fight microbial infection. Meanwhile, alterations in iron metabolism during sepsis lead to the development of some diseases, such as transfusion-induced siderosis and anemia. In recent years, several studies have demonstrated the use of iron-chelating agents to fight microbial infections, and new antimicrobial agents have been developed using "Trojan horse" and siderophores immunity. In addition, the use of iron-based nanomaterials as drug delivery systems for gene delivery may be applied to the treatment of sepsis in the future. In this review, we describe the pathophysiological changes in the development and course of sepsis, focusing on the potential of iron in the treatment of sepsis.

Modulation of immune cell function, IDO expression and kynurenine production by the quorum sensor 2-heptyl-3-hydroxy-4-quinolone (PQS)

Many invasive micro-organisms produce 'quorum sensor' molecules which regulate colony expansion and may modulate host immune responses. We have examined the ability of Pseudomonas Quorum Sensor (PQS) to influence cytokine expression under conditions of inflammatory stress. The administration of PQS in vivo to mice with collagen-induced arthritis (CIA) increased the severity of disease. Blood and inflamed paws from treated mice had fewer regulatory T cells (Tregs) but normal numbers of Th17 cells. However, PQS (1μM) treatment of antigen-stimulated lymph node cells from collagen-immunised mice in vitro inhibited the differentiation of CD4+IFNγ+ cells, with less effect on CD4+IL-17+ cells and no change in CD4+FoxP3+Tregs. PQS also inhibited T cell activation by anti-CD3/anti-CD28 antibodies. PQS reduced murine macrophage polarisation and inhibited expression of IL1B and IL6 genes in murine macrophages and human THP-1 cells. In human monocyte-derived macrophages, IDO1 gene, protein and enzyme activity were all inhibited by exposure to PQS. TNF gene expression was inhibited in THP-1 cells but not murine macrophages, while LPS-induced TNF protein release was increased by high PQS concentrations. PQS is known to have iron scavenging activity and its suppression of cytokine release was abrogated by iron supplementation. Unexpectedly, PQS decreased the expression of indoleamine-2, 3-dioxygenase genes (IDO1 and IDO2), IDO1 protein expression and enzyme activity in mouse and human macrophages. This is consistent with evidence that IDO1 inhibition or deletion exacerbates arthritis, while kynurenine reduces its severity. It is suggested that the inhibition of IDO1 and cytokine expression may contribute to the quorum sensor and invasive actions of PQS.

Complex differences in infection rates between ethnic groups in Scotland: a retrospective, national census-linked cohort study of 1.65 million cases

BACKGROUND

Ethnicity can influence susceptibility to infection, as COVID-19 has shown. Few countries have systematically investigated ethnic variations in infection.

METHODS

We linked the Scotland 2001 Census, including ethnic group, to national databases of hospitalizations/deaths and serological diagnoses of bloodborne viruses for 2001-2013. We calculated age-adjusted rate ratios (RRs) in 12 ethnic groups for all infections combined, 15 infection categories, and human immunodeficiency virus (HIV), hepatitis B (HBV) and hepatitis C (HCV) viruses.

RESULTS

We analysed over 1.65 million infection-related hospitalisations/deaths. Compared with White Scottish, RRs for all infections combined were 0.8 or lower for Other White British, Other White and Chinese males and females, and 1.2-1.4 for Pakistani and African males and females. Adjustment for socioeconomic status or birthplace had little effect. RRs for specific infection categories followed similar patterns with striking exceptions. For HIV, RRs were 136 in African females and 14 in males; for HBV, 125 in Chinese females and 59 in males, 55 in African females and 24 in males; and for HCV, 2.3-3.1 in Pakistanis and Africans.

CONCLUSIONS

Ethnic differences were found in overall rates and many infection categories, suggesting multiple causative pathways. We recommend census linkage as a powerful method for studying the disproportionate impact of COVID-19.

Bloodstream bacterial infections in thalassemic pediatric and adolescent patients after hematopoietic stem cell transplantation

BACKGROUND

Thalassemic patients usually require regular blood transfusions; however, HSCT can provide a cure. Incidence of IBI in pediatric patients post-HSCT is still scant.

OBJECTIVES

This study aimed to explore whether thalassemic patients had a different incidence of post-HSCT IBI compared with patients with other underlying diseases. Factors associated with IBI in the pediatric population undergoing HSCT were also investigated.

METHODS

In this retrospective cohort study, clinical data of pediatric patients who underwent HSCT during the period from 2011 to 2016 were reviewed and analyzed. The primary outcome was incidence of IBI within 1-year post-HSCT.

RESULTS

Of 123 patients, 53 were thalassemic. IBI was diagnosed in 23 patients within 1 year after HSCT (incidence: 19.5 episodes/1000 patients/month). The IBI incidence was lower in thalassemic patients than in patients with other underlying diseases (6.9 vs. 31.6 episodes/1000 patients/month). Having thalassemia as an underlying disease was the only factor associated with lower IBI in pediatric post-HSCT patients (hazard ratio: 0.245; 95% confidence interval, 0.080-0.748). In post-HSCT thalassemic patients, IBI mostly occurred within 100 days after HSCT, and most of these cases had catheter-related blood stream infection. The risk of IBI tended higher for haploidentical HSCT, but this difference was not statistically significantly different.

CONCLUSION

The IBI incidence after HSCT was lower in thalassemic patients than in those with other underlying diseases. Catheter-related blood stream infection was the major IBI in these patients. IBI was not a major complication in thalassemic pediatric patients undergoing HSCT.

Global Distribution and Clinical Features of Pythiosis in Humans and Animals

Pythiosis is a difficult-to-treat infectious disease caused by Pythium insidiosum. The condition is unfamiliar among healthcare workers. Manifestation of pythiosis is similar to other fungal infections, leading to misdiagnosis and delayed treatment. The geographical extent of pythiosis at a global scale is unclear. This study aimed to analyze the clinical information recorded in the scientific literature to comprehensively project epidemiological characteristics, clinical features, and future trends of pythiosis. From 1980 to 2021, 4203 cases of pythiosis in humans (n = 771; 18.3%) and animals (primarily horse, dog, and cow; n = 3432; 81.7%), with an average of 103 cases/year, were recruited. Pythiosis case reports significantly increased in the last decade. Pythiosis spanned 23 tropical, subtropical, and temperate countries worldwide. Some patients acquired pythiosis from a trip to an endemic country. Strikingly, 94.3% of human cases were in India and Thailand, while 79.2% of affected animals were in the U.S.A. and Brazil. Clinical features of pythiosis varied. Vascular and ocular pythiosis were only observed in humans, whereas cutaneous/subcutaneous and gastrointestinal infections were predominant in animals. Mortality depended on host species and clinical forms: for example, none in patients with ocular pythiosis, 0.7% in cows with a cutaneous lesion, 26.8% in humans with vascular disease, 86.4% in dogs with gastrointestinal pathology, and 100% in several animals with disseminated infection. In summary, this study reports up-to-date epidemiological and clinical features of pythiosis in humans and animals. It increases awareness of this life-threatening disease, as the illness or outbreak can exist in any country, not limited to the endemic areas.

Increased non-typhoidal Salmonella hospitalizations in transfusion-naïve thalassemia children: a nationwide population-based cohort study

INTRODUCTION

Although non-typhoidal Salmonella (NTS) infection usually causes self-limited enterocolitis, several risk factors have been found to predispose individuals to more severe NTS infections. However, few studies have discussed the association between NTS infection and pediatric thalassemia populations.

MATERIAL AND METHODS

A nationwide population-based retrospective cohort study was conducted using medical records of the selected children from the Taiwan National Health Insurance Research Database. Immunocompromised individuals or patients with a history of transfusion or splenectomy were excluded. One thalassemia patient was matched with four non-thalassemia patients based on their year of birth, sex, and urbanization level.

RESULTS

In this cohort, 912 patients with thalassemia and 3648 comparison cohort were analyzed. The mean age of NTS hospitalization was 2.0 ± 1.4 in thalassemia cohort and 2.6 ± 2.4 in non-thalassemia cohort. Transfusion-naïve thalassemia children were proved to have a higher rate of NTS hospitalization (6.90 vs 4.11 per 1000 person-year; p = 0.0004) than the non-thalassemia cohort, with an adjusted hazard ratio (HR) of 1.68 (95% confidence interval [CI] = 1.26-2.24).

CONCLUSION

Our research shows that transfusion-naïve thalassemia is associated with an increased risk of NTS hospitalization. Further prospective study comparing the incidence and severity of NTS infection among children with and without thalassemia is needed.

IMPACT

Pediatric transfusion-naïve thalassemia patients have an 1.68-fold increased risk for hospitalization due to non-typhoidal Salmonella (NTS) infection. This is the first nationwide population-based cohort study based on an extremely large database that shows pediatric transfusion-naïve thalassemia patients have an increased risk for NTS hospitalizations. Besides the previously known risk factors such as extremes of age, sickle cell disease, or immunosuppressing conditions, clinicians must also take thalassemia as a possible risk factor for more severe NTS disease.

The role of iron homeostasis in remodeling immune function and regulating inflammatory disease

The essential trace element iron regulates a wide range of biological processes in virtually all living organisms. Because both iron deficiency and iron overload can lead to various pathological conditions, iron homeostasis is tightly regulated, and understanding this complex process will help pave the way to developing new therapeutic strategies for inflammatory disease. In recent years, significant progress has been made with respect to elucidating the roles of iron and iron-related genes in the development and maintenance of the immune system. Here, we review the timing and mechanisms by which systemic and cellular iron metabolism are regulated during the inflammatory response and during infectious disease, processes in which both the host and the pathogen compete for iron. We also discuss the evidence and implications that immune cells such as macrophages, T cells, and B cells require sufficient amounts of iron for their proliferation and for mediating their effector functions, in which iron serves as a co-factor in toll-like receptor 4 (TLR4) signaling, mitochondrial respiration, posttranslational regulation, and epigenetic modification. In addition, we discuss the therapeutic implications of targeting ferroptosis, iron homeostasis and/or iron metabolism with respect to conferring protection against pathogen infection, controlling inflammation, and improving the efficacy of immunotherapy.

Pathomechanisms of Immunological Disturbances in β-Thalassemia

Thalassemia, a chronic disease with chronic anemia, is caused by mutations in the β-globin gene, leading to reduced levels or complete deficiency of β-globin chain synthesis. Patients with β-thalassemia display variable clinical severity which ranges from asymptomatic features to severe transfusion-dependent anemia and complications in multiple organs. They not only are at increased risk of blood-borne infections resulting from multiple transfusions, but they also show enhanced susceptibility to infections as a consequence of coexistent immune deficiency. Enhanced susceptibility to infections in β-thalassemia patients is associated with the interplay of several complex biological processes. β-thalassemia-related abnormalities of the innate immune system include decreased levels of complement, properdin, and lysozyme, reduced absorption and phagocytic ability of polymorphonuclear neutrophils, disturbed chemotaxis, and altered intracellular metabolism processes. According to available literature data, immunological abnormalities observed in patients with thalassemia can be caused by both the disease itself as well as therapies. The most important factors promoting such alterations involve iron overload, phenotypical and functional abnormalities of immune system cells resulting from chronic inflammation oxidative stress, multiple blood transfusion, iron chelation therapy, and splenectomy. Unravelling the mechanisms underlying immune deficiency in β-thalassemia patients may enable the designing of appropriate therapies for this group of patients.

Increased susceptibility to dextran sulfate-induced mucositis of iron-overload β-thalassemia mice, another endogenous cause of septicemia in thalassemia

Enterocyte damage and gut dysbiosis are caused by iron-overload in thalassemia (Thl), possibly making the gut vulnerable to additional injury. Hence, iron-overload in the heterozygous β-globin deficient (Hbb^th3/+) mice were tested with 3% dextran sulfate solution (DSS).

With 4 months of iron-gavage, iron accumulation, gut-leakage (fluorescein isothiocyanate dextran (FITC-dextran), endotoxemia, and tight junction injury) in Thl mice were more prominent than WT mice. Additionally, DSS-induced mucositis in iron-overloaded mice from Thl group was also more severe than the WT group as indicated by mortality, liver enzyme, colon injury (histology and tissue cytokines), serum cytokines, and gut-leakage (FITC-dextran, endotoxemia, bacteremia, and the detection of Green-Fluorescent Producing Escherichia coli in the internal organs after an oral administration). However, Lactobacillus rhamnosus GG attenuated the disease severity of DSS in iron-overloaded Thl mice as indicated by mortality, cytokines (colon tissue and serum), gut-leakage (FITC-dextran, endotoxemia, and bacteremia) and fecal dysbiosis (microbiome analysis). Likewise, Lactobacillus conditioned media (LCM) decreased inflammation (supernatant IL-8 and cell expression of TLR-4, nuclear factor κB (NFκB), and cyclooxygenase-2 (COX-2)) and increased transepithelial electrical resistance (TEER) in enterocytes (Caco-2 cells) stimulated by lipopolysaccharide (LPS) and LPS plus ferric ion.

In conclusion, in the case of iron-overloaded Thl, there was a pre-existing intestinal injury that wask more vulnerable to DSS-induced bacteremia (gut translocation). Hence, the prevention of gut-derived bacteremia and the monitoring on gut-leakage might be beneficial in patients with thalassemia.

Increased zinc and albumin but lowered copper in children with transfusion-dependent thalassemia

BACKGROUND

Measurements of copper and zinc in transfusion-dependent thalassemia (TDT) show contradictory results.

AIM OF THE STUDY

To examine serum levels of these minerals in TDT in relation to iron overload indices and erythron variables.

METHODS

This study recruited 60 children with TDT and 30 healthy controls aged 3-12 years old.

RESULTS

Zinc was significantly higher in TDT children than in controls, while copper and the copper to zinc ratio were significantly lowered in TDT. Serum zinc was significantly associated with the number of blood transfusions and iron overload variables (including serum iron and TS%) and negatively with erythron variables (including hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin). Serum copper was significantly and negatively associated with the same iron overload and erythron variables. The copper to zinc ratio was significantly correlated with iron, TS%, ferritin, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin. Albumin levels were significantly higher in TDT children than in control children.

CONCLUSION

Our results suggest that the increase in zinc in children with TDT may be explained by iron loading anemia and hemolysis and the consequent shedding of high amounts of intracellular zinc into the plasma. Increased albumin levels and treatment with Desferral may further contribute towards higher zinc levels in TDT. We suggest that the elevations in zinc in TDT are a compensatory mechanism protecting against infection, inflammation, and oxidative stress. Previous proposals for prophylactic use of zinc supplements in TDT may not be warranted.

The hypoferremic response to acute inflammation is maintained in thalassemia mice even under parenteral iron loading

Background

Hepcidin controls iron homeostasis by inducing the degradation of the iron efflux protein, ferroportin (FPN1), and subsequently reducing serum iron levels. Hepcidin expression is influenced by multiple factors, including iron stores, ineffective erythropoiesis, and inflammation. However, the interactions between these factors under thalassemic condition remain unclear. This study aimed to determine the hypoferremic and transcriptional responses of iron homeostasis to acute inflammatory induction by lipopolysaccharide (LPS) in thalassemic (Hbb^th3/+) mice with/without parenteral iron loading with iron dextran.

Methods

Wild type and Hbb^th3/+ mice were intramuscularly injected with 5 mg of iron dextran once daily for two consecutive days. After a 2-week equilibration, acute inflammation was induced by an intraperitoneal injection of a single dose of 1 µg/g body weight of LPS. Control groups for both iron loading and acute inflammation received equal volume(s) of saline solution. Blood and tissue samples were collected at 6 hours after LPS (or saline) injection. Iron parameters and mRNA expression of hepcidin as well as genes involved in iron transport and metabolism in wild type and Hbb^th3/+ mice were analyzed and compared by Kruskal–Wallis test with pairwise Mann–Whitney U test.

Results

We found the inductive effects of LPS on liver IL-6 mRNA expression to be more pronounced under parenteral iron loading. Upon LPS administration, splenic erythroferrone (ERFE) mRNA levels were reduced only in iron-treated mice, whereas, liver bone morphogenetic protein 6 (BMP6) mRNA levels were decreased under both control and parenteral iron loading conditions. Despite the altered expression of the aforementioned hepcidin regulators, the stimulatory effect of LPS on hepcidin mRNA expression was blunt in iron-treated Hbb^th3/+ mice. Contrary to the blunted hepcidin response, LPS treatment suppressed FPN1 mRNA expression in the liver, spleen, and duodenum, as well as reduced serum iron levels of Hbb^th3/+ mice with parenteral iron loading.

Conclusion

Our study suggests that a hypoferremic response to LPS-induced acute inflammation is maintained in thalassemic mice with parenteral iron loading in a hepcidin-independent manner.

Frequency of Hepatitis B, C and HIV Infections among Transfusion-Dependent Beta Thalassemia Patients in Dhaka

Transfusion transmitted infections have remained a major deterrent to public health, particularly among the patients with transfusion-dependent Beta thalassemia in developing countries. Although proper donor selection through adoption of WHO-advised infection panel has lowered the rate of infections, the multi-transfused patients are not free of risk. In this study, we screened 148 transfusion-dependent Beta thalassemia patients to determine the frequency of Hepatitis C Virus (HCV), Hepatitis B Virus (HBV) and Human Immunodeficiency Virus (HIV) using the ELISA method. Among them, infected cases with HCV, HBV and HIV were 13.51%, 3.37% and 0%, respectively. Moreover, 2% of the patients were found to be co-infected with both HBV and HCV. The percentage of infections in the patients with frequent transfusion interval (≤30 days) was significantly higher (p < 0.0005) than that in the patients with less frequent transfusion intervals (>30 days). Immunochromatography (ICT)-based rapid test kits are usually used to screen and confirm these infections in the blood of the patients. However, ICT-based tests are not sensitive enough to detect the infections. So, a combination of both Nucleic Acid testing (NAT) and serological testing are suggested to significantly reduce the risk of viral infections during blood transfusion.

Erythroferrone structure, function, and physiology: Iron homeostasis and beyond

Erythroferrone (ERFE) is the main erythroid regulator of hepcidin, the homeostatic hormone controlling plasma iron levels and total body iron. When the release of erythropoietin from the kidney stimulates the production of new red blood cells, it also increases the synthesis of ERFE in bone marrow erythroblasts. Increased ERFE then suppresses hepcidin synthesis, thereby mobilizing cellular iron stores for use in heme and hemoglobin synthesis. Recent mechanistic studies have shown that ERFE suppresses hepcidin transcription by inhibiting bone morphogenetic protein signaling in hepatocytes. In ineffective erythropoiesis, pathological overproduction of ERFE by an expanded population of erythroblasts suppresses hepcidin and causes iron overload, even in non-transfused patients. ERFE may be a useful biomarker of ineffective erythropoiesis and an attractive target for treating its systemic effects.

Pathogen-Associated Molecules from Gut Translocation Enhance Severity of Cecal Ligation and Puncture Sepsis in Iron-Overload β-Thalassemia Mice

Introduction

Systemic inflammation induced by gut translocation of lipopolysaccharide (LPS), a major component of Gram-negative bacteria, in thalassemia with iron-overload worsens sepsis. However, the impact of (1→3)-β-D-glucan (BG), a major fungal molecule, in iron-overload thalassemia is still unclear. Hence, the influence of BG was explored in 1) iron-overload mice with sepsis induced by cecal ligation and puncture (CLP) surgery; and 2) in bone marrow-derived macrophages (BMMs).

Methods

The heterozygous β-globin-deficient mice, Hbb^th3/+ mice, were used as representative thalassemia (TH) mice. Iron overload was generated by 6 months of oral iron administration before CLP surgery- induced sepsis in TH mice and wild-type (WT) mice. Additionally, BMMs from both mouse strains were used to explore the impact of BG.

Results

Without sepsis, iron-overload TH mice demonstrated more severe intestinal mucosal injury (gut leakage) with higher LPS and BG in serum, from gut translocation, when compared with WT mice. With CLP in iron-overload mice, sepsis severity in TH mice was more severe than WT as determined by survival analysis, organ injury (kidney and liver), bacteremia, endotoxemia, gut leakage (FITC-dextran) and serum BG. Activation by LPS plus BG (LPS+BG) in BMMs and in peripheral blood-derived neutrophils (both WT and TH cells) demonstrated more prominent cytokine production when compared with LPS activation alone. In parallel, LPS+BG also prominently induced genes expression of M1 macrophage polarization (iNOS, TNF-α and IL-1β) in both WT and TH cells in comparison with LPS activation alone. In addition, LPS+BG activated macrophage cytokine production was enhanced by a high dose of ferric ion (800 mM), more predominantly in TH macrophages compared with WT cells. Moreover, LPS+BG induced higher glycolysis activity with similar respiratory capacity in RAW264.7 (a macrophage cell line) compared with LPS activation alone. These data support an additive pro-inflammatory effect of BG upon LPS.

Conclusion

The enhanced-severity of sepsis in iron-overload TH mice was due to 1) increased LPS and BG in serum from iron-induced gut-mucosal injury; and 2) the pro-inflammatory amplification by ferric ion on LPS+BG activation.

Prevalence of Alpha(α)-Thalassemia in Southeast Asia (2010-2020): A Meta-Analysis Involving 83,674 Subjects

Alpha(α)-thalassemia is a blood disorder caused by many types of inheritable α-globin gene mutations which causes no-to-severe clinical symptoms, such as Hb Bart's hydrops fetalis that leads to early foetal death. Therefore, the aim of this meta-analysis was to provide an update from year 2010 to 2020 on the prevalence of α-thalassemia in Southeast Asia. A systematic literature search was performed using PubMed and SCOPUS databases for related studies published from 2010 to 2020, based on specified inclusion and exclusion criteria. Heterogeneity of included studies was examined with the I2 index and Q-test. Funnel plots and Egger's tests were performed in order to determine publication bias in this meta-analysis. Twenty-nine studies with 83,674 subjects were included and pooled prevalence rates in this meta-analysis were calculated using random effect models based on high observed heterogeneity (I2 > 99.5, p-value < 0.1). Overall, the prevalence of α-thalassemia is 22.6%. The highest α-thalassemia prevalence was observed in Vietnam (51.5%) followed by Cambodia (39.5%), Laos (26.8%), Thailand (20.1%), and Malaysia (17.3%). No publication bias was detected. Conclusions: This meta-analysis suggested that a high prevalence of α-thalassemia occurred in selected Southeast Asia countries. This meta-analysis data are useful for designing thalassemia screening programs and improve the disease management.

Iron in infection and immunity

Iron is an essential micronutrient for virtually all living cells. In infectious diseases, both invading pathogens and mammalian cells including those of the immune system require iron to sustain their function, metabolism and proliferation. On the one hand, microbial iron uptake is linked to the virulence of most human pathogens. On the other hand, the sequestration of iron from bacteria and other microorganisms is an efficient strategy of host defense in line with the principles of 'nutritional immunity'. In an acute infection, host-driven iron withdrawal inhibits the growth of pathogens. Chronic immune activation due to persistent infection, autoimmune disease or malignancy however, sequesters iron not only from infectious agents, autoreactive lymphocytes and neoplastic cells but also from erythroid progenitors. This is one of the key mechanisms which collectively result in the anemia of chronic inflammation. In this review, we highlight the most important interconnections between iron metabolism and immunity, focusing on host defense against relevant infections and on the clinical consequences of anemia of inflammation.

Phenotypical and functional abnormalities of circulating neutrophils in patients with β-thalassemia

β-Thalassemia is an inherited single gene disorder related to reduced synthesis of the β-globin chain of hemoglobin. Patients with β-thalassemia present variable clinical severity ranging from asymptomatic trait to severe transfusion-dependent anemia and multiple organs complications. Moreover, multiple immune abnormalities are a major concern in β-thalassemia patients. Aberrant neutrophil effector function plays a pivotal role in infection susceptibility in these patients. In severe and persistent inflammation, immature neutrophils are released from the bone marrow and are functionally different compared with mature ones. Despite some abnormalities reported for thalassemia patient's immune system, few data exist on the characterization of human neutrophils in β-thalassemia. The aim of this study was to investigate the phenotype and function of circulating neutrophil subsets in patients with β-thalassemia major and with β-thalassemia intermedia divided in transfusion-dependent and non-transfusion-dependent. By the use of immunochemical and cytofluorimetric analyses, we observed that patients' CD16+ neutrophils exhibit abnormalities in their phenotype and functions and the abnormalities vary according to the clinical form of the disease and to the neutrophil subset (CD16^bright and CD16^dim). Abnormalities include altered surface expression of the innate immune receptor CD45, Toll-like receptor 4, and CD32, reduced ability to produce an oxidative burst, and elevated levels of membrane lipid peroxidation, especially in patients with a more severe form of the disease. Overall, our results indicating the occurrence of an immuno-senescent phenotype on circulating neutrophils from thalassemia patients suggest the usefulness of neutrophil feature assessment as a tool for better clinical management of β-thalassemia.

Klebsiella pneumoniae Multiple Liver Abscesses and Bacteremia in a Transfusion-dependent β Thalassemia Major Patient

β thalassemia major is a common hemoglobinopathy in Sri Lanka. Klebsiella pneumoniae (KP) is a Gram-negative capsulated organism responsible for various nosocomial and community-acquired infections. Transfusion-dependent splenectomized thalassemia patients are at risk of infections. Liver abscess is an infection to suspect in such patients, and, among the organisms, KP is an organism to watch out for. Furthermore, KP could cause multiple liver abscesses, which makes it difficult to treat, as it cannot be drained. We report a 16-year-old splenectomized transfusion-dependent thalassemia major patient who presented with multiple liver abscesses with KP bacteremia.

Immune responses in beta-thalassaemia: heme oxygenase 1 reduces cytokine production and bactericidal activity of human leucocytes

Patients with beta-thalassaemia increase the risk of bacterial infections, particularly Burkholderia pseudomallei (Bp), the causative agent of melioidosis in Thailand. Impaired immune cell functions may be the cause of this susceptibility, but detailed mechanisms have not been defined. In this study, we observed impaired production of IFN-gamma and IL-10 by whole blood from beta-thalassaemia patients upon stimulation with a range of bacteria-derived stimuli. In contrast, IFN-gamma response via TCR and plasma IgG specific for Bp were still intact. Importantly, mRNA expression of heme oxygenase 1 (HO-1), a potential modulator of immune function, was increased in whole blood from beta-thalassaemia patients, either with or without stimulation with Bp in vitro. Induction of HO-1 by hemin or CoPP in vitro reduced production of IFN-gamma and IL-10 from healthy human PBMCs and decreased bacterial clearance activity of whole blood from healthy controls and beta-thalassaemia, while inhibition of HO-1 by SnPP enhanced both functions in healthy controls. These results were confirmed to some extent in purified human monocytes of healthy controls. Our results suggest a mechanism that excess hemin of beta-thalassaemia patients is a significant cause of immune suppression via HO-1 induction and may underlie the susceptibility of these individuals to severe bacterial infection.

Emphysematous osteomyelitis caused by Salmonella typhi in beta thalassemia major

There have been various cases of salmonella osteomyelitis reported in sickle cell anemia. We present a case of emphysematous osteomyelitis caused by Salmonella typhi in a 29-year-old beta thalassemia major patient. Diagnosis of emphysematous osteomyelitis was confirmed by computed tomography and magnetic resonance imaging, and culture of pus drained during surgical debridement confirmed the causative microorganism, Salmonella typhi. Antimicrobials were given according to microbiological sensitivity for a period of 8 weeks. Our patient also received hyperbaric oxygen therapy. At the end of therapy, he was afebrile and laboratory parameters normalized with a residual joint deformity which developed within 3 months.

Gut leakage enhances sepsis susceptibility in iron-overloaded β-thalassemia mice through macrophage hyperinflammatory responses

Iron overload induces intestinal-permeability defect (gut leakage), and gut translocation of organismal molecules might enhance systemic inflammation and sepsis severity in patients with thalassemia (Thal). Hence, iron administration in Hbb^th3/+ mice, heterozygous β-globin-deficient Thal mice, was explored. Oral iron administration induced more severe secondary hemochromatosis and gut leakage in Thal mice compared with wild-type (WT) mice. Gut leakage was determined by 1) FITC-dextran assay, 2) spontaneous serum elevation of endotoxin (LPS) and (1→3)-β-d-glucan (BG), molecular structures of gut-organisms, and 3) reduction of tight-junction molecules with increased enterocyte apoptosis (activated caspase-3) by immunofluorescent staining. Iron overload also enhanced serum cytokines and increased Bacteroides spp. (gram-negative bacteria) in feces as analyzed by microbiome analysis. LPS injection in iron-overloaded Thal mice produced higher mortality and prominent cytokine responses. Additionally, stimulation with LPS plus iron in macrophage from Thal mice induced higher cytokines production with lower β-globin gene expression compared with WT. Furthermore, possible gut leakage as determined by elevated LPS or BG (>60 pg/mL) in serum without systemic infection was demonstrated in 18 out of 41 patients with β-thalassemia major. Finally, enhanced LPS-induced cytokine responses of mononuclear cells from these patients compared with cells from healthy volunteers were demonstrated. In conclusion, oral iron administration in Thal mice induced more severe gut leakage and increased fecal gram-negative bacteria, resulting in higher levels of endotoxemia and serum inflammatory cytokines compared with WT. Preexisting hyperinflammatory cytokines in iron-overloaded Thal enhanced susceptibility toward infection.NEW & NOTEWORTHY Although the impact of iron accumulation in several organs of patients with thalassemia is well known, the adverse effect of iron accumulation in gut is not frequently mentioned. Here, we demonstrated iron-induced gut-permeability defect, impact of organismal molecules from gut translocation of, and macrophage functional defect upon the increased sepsis susceptibility in thalassemia mice.

Increased incidence of infection in patients with myelofibrosis and transfusion-associated iron overload in the clinical setting

Transfusion-associated iron overload may lead to increased risk of infection, but its role in myelofibrosis (MF) has been scarcely explored. We evaluated 106 consecutive patients with primary or secondary MF. Up to 38% of patients were transfusion-dependent (TD) with a median of 14 RBC units received. Median observation time was 36 months (range 3-203). Forty-five percent of patients experienced one or more infectious episodes for a total of 69 infectious events, 13 (19%) of which were severe. The 60-month cumulative incidence of infection was 64.1 ± 6.5%. TD patients showed a higher incidence of infection (HR = 2.13, p = 0.019). Transfusion burden was markedly greater in TD patients with infectious complication (median 24 RBC units vs 15 RBC units; p = 0.012). The 60-month overall survival was 40 ± 5.9%. Lower International Prognostic Scoring System (IPSS) risk (p < 0.0001) and ruxolitinib (p = 0.027) were significantly correlated with higher survival. This real-world study showed increased infections in patients with higher transfusion burden. It may therefore be interesting to further investigate the role of iron chelation in improving infection-free survival in MF patients.

Reproductive health issues in female patients with beta-thalassaemia major: a narrative literature review

β-thalassaemia major (BTM) has a high prevalence worldwide and is associated with considerable morbidity and mortality. The aim of this review is to provide an illustrative overview of the reproductive health and pregnancy related issues in females with β-thalassaemia. A literature search was performed in four international databases (1980-2018) to identify the potentially relevant articles. Common reproductive health disorders are hypo-gonadotrophic hypogonadism, infertility, delayed or absent sexual development, diabetes, hypothyroidism, hypoparathyroidism, osteopenia, preeclampsia, gestational hypertension, polyhydramnios, oligohydramnios, thrombosis, renal failure, peripheral vascular resistance, placenta previa, pleural effusion and pulmonary hypertension. Many of those aspects are related to iron overload and to ineffective erythropoiesis. Foetal complications include neural tube defects, abnormalities in different organs, spontaneous abortion, foetal loss, preterm birth, foetal growth restriction and low birth weight. Antenatal screening and accurate genetic prenatal examinations are effective measures to early diagnosis of thalassaemia and a detailed plan for management of pregnancies in BTM is important for favourable maternal and foetal outcome.

N-acetylcysteine Restored Heart Rate Variability and Prevented Serious Adverse Events in Transfusion-dependent Thalassemia Patients: a Double-blind Single Center Randomized Controlled Trial

Regular blood transfusions in transfusion-dependent thalassemia (TDT) patients can lead to iron overload, causing oxidative stress and sympathovagal imbalance, resulting in increased cardiac complications. We hypothesized that administrating of N-acetylcysteine (NAC) prevents serious adverse events including cardiac complications in TDT patients by reducing systemic oxidative stress and balancing cardiac sympathovagal control. This study was double-blind, randomized control trial, investigating in 59 Thai TDT patients. After randomization, the participants were divided into two groups. The control group received standard care of TDT patient plus placebo, whereas the intervention group received 600 mg of NAC orally for six months. Serum 8-isoprostane, TNF-alpha, IL-10, 24-hour ECG monitoring, echocardiograms and the incidence of thalassemia-related complications were collected. At baseline, no significant difference in any parameters between the control and the intervention groups. At the end of intervention, the incidence of serious adverse events (i.e. infection, worsening thalassemia) was significantly higher in the control group when compared with the intervention group (24.1% vs. 3.3%, p=0.019) (Chi-square test; absolute risk reduction=20.8%, number needed to treat=4.8). The control group also had significantly lower time-dependent HRV parameters, compared with the intervention group (p=0.025 and 0.030, independent t-test). Treatment with NAC restored HRV and reduced serious adverse event in TDT patients, however, no difference in cardiac complications could be demonstrated. NAC could prevent serious adverse events in TDT patients. The proposed mechanism might be the balancing of sympathovagal control.

Higher Hospitalization Rate for Lower Airway Infection in Transfusion-Naïve Thalassemia Children

Few studies have addressed the risk of infection in transfusion-naïve thalassemia patients. We aimed to investigate whether transfusion-naïve thalassemia population has higher hospitalization rates for lower airway infection-related diseases than non-thalassemia population in children. A nationwide population-based retrospective cohort study was conducted using detailed medical records of the Taiwan National Health Insurance Research Database. Transfusion-naïve thalassemia patients were compared with a matched cohort at a ratio of 1:4. Data of the selected patients were adjusted for age, sex, and related comorbidities. We recorded the frequency of admissions or outpatient clinic visits for patients with a diagnosis of pneumonia or acute bronchitis/bronchiolitis. Based on our results, the hospitalization rates and incidence rate ratios of bronchitis/bronchiolitis and pneumonia for transfusion-naïve thalassemia children were all higher than those for non-thalassemia controls. Therefore, we conclude that transfusion-naïve thalassemia children are more likely to experience lower airway infections and have a higher probability of hospitalization for these conditions.

Iron in Health and Disease: An Update

Iron is an essential micronutrient for oxygen transport, cellular energy metabolism, and many enzymatic reactions. Complex physiological processes have evolved for iron acquisition to meet metabolic needs while avoiding toxicity from iron-generated free radicals. Systemic iron homeostasis is centered around the regulation of iron absorption from duodenum and iron release from stores by hepcidin. Intracellular iron is maintained under tight control by iron regulatory proteins acting at post-transcriptional level. Despite these elaborate mechanisms, iron status is frequently altered by environmental or genetic influences. Iron deficiency anemia is the most common nutritional disorder affecting a quarter of the world population. Iron deficiency is associated with impaired cognitive development and reduced capacity for physical work, making it a high priority for public health initiatives. Chronic inflammation from infections or other causes limits iron availability and contributes to anemia of chronic disease. At the opposite end are conditions where iron overload leads to serious complications from organ damage. Mutations in HFE gene are the most frequent cause of hereditary hemochromatosis in European population, but rare elsewhere in the world. Iron overload develops in dyserythropoietic anemias from increased intestinal absorption. Transfusional iron overload, most often observed in thalassemia, is increasing among cancer survivors due to the use of protocols requiring intensive transfusion support. Tissue-specific brain iron overload is observed in some degenerative neurological diseases without an increase in systemic iron. New insights into iron metabolism are guiding the development of novel therapies for iron deficiency and iron overload.

Increased ferritin levels in non-transfusion-dependent β°-thalassaemia/HbE are associated with reduced CXCR2 expression and neutrophil migration

Severe bacterial infection is a major complication causing morbidity and mortality in β-thalassaemia/HbE patients. Innate immunity constitutes the first line of defence against bacterial infection. This study aimed to comprehensively investigate the innate immune phenotype and function related to factors predisposing to infection in non-transfusion-dependent (NTD) β°-thalassaemia/HbE patients. Twenty-six patients and 17 healthy subjects were recruited to determine complement activity (C3, C4, mannose-binding lectin and CH50) and surface receptor expression including markers of phagocytosis (CD11b, CD16 and C3bR), inflammation (C5aR) and migration (CD11b, CXCR1 and CXCR2) on neutrophils and monocytes. In addition, phagocytosis and oxidative burst activity of neutrophils and monocytes against Escherichia coli and neutrophil migration were examined. Decreased C3 and surface expression of CD11b and C3bR on neutrophils were found in patients. However, phagocytosis of neutrophils in patients was still in the normal range. Interestingly, patients displayed a significant reduction of surface expression of CXCR2 [1705 ± 217 mean fluorescent intensity (MFI)] on neutrophils, leading to impaired neutrophil migration (9·2 ± 7·7%) when compared to neutrophils from healthy subjects (2261 ± 627 MFI and 27·8 ± 9% respectively). Moreover, surface expression of CXCR2 on neutrophils was associated with splenectomy status, serum ferritin and haemoglobin levels. Therefore, impaired neutrophil migration could contribute to the increased susceptibility to infection seen in NTD β°-thalassaemia/HbE patients.

Bone marrow stromal cells from β-thalassemia patients have impaired hematopoietic supportive capacity

BACKGROUND. The human bone marrow (BM) niche contains a population of mesenchymal stromal cells (MSCs) that provide physical support and regulate hematopoietic stem cell (HSC) homeostasis. β-Thalassemia (BT) is a hereditary disorder characterized by altered hemoglobin beta-chain synthesis amenable to allogeneic HSC transplantation and HSC gene therapy. Iron overload (IO) is a common complication in BT patients affecting several organs. However, data on the BM stromal compartment are scarce.

METHODS. MSCs were isolated and characterized from BM aspirates of healthy donors (HDs) and BT patients. The state of IO was assessed and correlated with the presence of primitive MSCs in vitro and in vivo. Hematopoietic supportive capacity of MSCs was evaluated by transwell migration assay and 2D coculture of MSCs with human CD34⁺ HSCs. In vivo, the ability of MSCs to facilitate HSC engraftment was tested in a xenogenic transplant model, whereas the capacity to sustain human hematopoiesis was evaluated in humanized ossicle models.

RESULTS. We report that, despite iron chelation, BT BM contains high levels of iron and ferritin, indicative of iron accumulation in the BM niche. We found a pauperization of the most primitive MSC pool caused by increased ROS production in vitro which impaired MSC stemness properties. We confirmed a reduced frequency of primitive MSCs in vivo in BT patients. We also discovered a weakened antioxidative response and diminished expression of BM niche–associated genes in BT-MSCs. This caused a functional impairment in MSC hematopoietic supportive capacity in vitro and in cotransplantation models. In addition, BT-MSCs failed to form a proper BM niche in humanized ossicle models.

CONCLUSION. Our results suggest an impairment in the mesenchymal compartment of BT BM niche and highlight the need for novel strategies to target the niche to reduce IO and oxidative stress before transplantation.

FUNDING. This work was supported by the SR-TIGET Core grant from Fondazione Telethon and by Ricerca Corrente.

The Effect of Transfusion-Dependent Thalassemia Patient's Serum on Peripheral Blood Mononuclear Cell Viability

Iron overload is a major complication in transfusion-dependent thalassemia (TDT) patients. Chronic oxidative stress from iron overload may lead to cellular damage and viability. This is a cross-sectional study. Transfusion-dependent thalassemia patients aged ⩾18 years old were enrolled. Transfusion-dependent thalassemia patient’s serum and normal volunteer’s serum were separately incubated with healthy peripheral blood mononuclear cells (PBMCs). The cell viability was measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay at 24, 48, and 72 hours. Sixty-nine TDT patients and 22 healthy controls were enrolled. The mean of PBMCs viability after incubation with serum from TDT patients was lower than that with the controls (88.65% vs 103.56% at 24 hours, 78.77% vs 112.04%% at 48 hours, and 71.18% vs 132.16%% at 72 hours, respectively). High serum ferritin level (correlation −0.29, P < .05) and white blood cell (WBC) count negatively affected cell viability (correlation −2.86, P = .05). From multivariate analysis, serum ferritin level is the only significant risk factor that is independently associated with cell viability (correlation −11.42, P < .001). Our findings showed that TDT patient’s serum causes decreased cell viability. Serum ferritin level was a significant independent factor influencing cell viability.

Iron and innate antimicrobial immunity-Depriving the pathogen, defending the host

The acute-phase response is triggered by the presence of infectious agents and danger signals which indicate hazards for the integrity of the mammalian body. One central feature of this response is the sequestration of iron into storage compartments including macrophages. This limits the availability of this essential nutrient for circulating pathogens, a host defence strategy known as 'nutritional immunity'. Iron metabolism and the immune response are intimately linked. In infections, the availability of iron affects both the efficacy of antimicrobial immune pathways and pathogen proliferation. However, host strategies to withhold iron from microbes vary according to the localization of pathogens: Infections with extracellular bacteria such as Staphylococcus aureus, Streptococcus, Klebsiella or Yersinia stimulate the expression of the iron-regulatory hormone hepcidin which targets the cellular iron-exporter ferroportin-1 causing its internalization and blockade of iron egress from absorptive enterocytes in the duodenum and iron-recycling macrophages. This mechanism disrupts both routes of iron delivery to the circulation, contributes to iron sequestration in the mononuclear phagocyte system and mediates the hypoferraemia of the acute phase response subsequently resulting in the development of anaemia of inflammation. When intracellular microbes are present, other strategies of microbial iron withdrawal are needed. For instance, in macrophages harbouring intracellular pathogens such as Chlamydia, Mycobacterium tuberculosis, Listeria monocytogenes or Salmonella Typhimurium, ferroportin-1-mediated iron export is turned on for the removal of iron from infected cells. This also leads to reduced iron availability for intra-macrophage pathogens which inhibits their growth and in parallel strengthens anti-microbial effector pathways of macrophages including the formation of inducible nitric oxide synthase and tumour necrosis factor. Iron plays a key role in infectious diseases both as modulator of the innate immune response and as nutrient for microbes. We need to gain a more comprehensive understanding of how the body can differentially respond to infection by extra- or intracellular pathogens. This knowledge may allow us to modulate mammalian iron homeostasis pharmaceutically and to target iron-acquisition systems of pathogens, thus enabling us to treat infections with novel strategies that act independent of established antimicrobials.