Gut leakage enhances sepsis susceptibility in iron-overloaded ß-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 Hbbth3/+ mice, heterozygous ß-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)-ß-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 ß-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 ß-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.

Differential gut microbiota composition in ß-Thalassemia patients and its correlation with iron overload.

Recent research highlights the significant impact of the gut microbiota on health and disease. Thalassemia, a hereditary blood disorder, requires regular blood transfusions, leading to an accumulation of iron in the body. Such changes could potentially alter the intestinal microbiota, thereby increasing the susceptibility of thalassemic patients to infection. In this study, we analyzed the fecal microbiota of 70 non-transfusion-dependent (NTDT) ß-thalassemia/HbE patients and 30 healthy controls. Our findings indicate that iron chelation intervention had no detectable effect on the microbiome profile of thalassemic patients. However, the cross-sectional analysis revealed that the bacterial diversity and community structure in patients were significantly less diverse and distinct compared to those of healthy subjects. Using reference frames, we were also able to demonstrate that bacterial taxa that are known to produce short chain fatty acids, from the genera Alistipes, Coprococcus, and Oscillospira, and those from the family Ruminococcaceae, were less prevalent in the patients. In contrast, bacterial taxa associated with an unhealthy gut, including the genus Clostridium and those from the families Fusobacteriaceae, Enterobacteriaceae, and Peptostrptococcaceae, were more prevalent in patients and found to be correlated with higher levels of ferritin. Collectively, these changes in the microbiota could be regarded as markers of raised ferritin levels, and therefore, awareness should be exercised as they could interfere, albeit indirectly, with the treatment of the co-morbidities of thalassemia.

Impaired neutrophil extracellular trap formation in ß-thalassaemia/HbE.

Neutrophil dysfunction contributes to a high susceptibility to severe bacterial infection which is a leading cause of morbidity and mortality in ß-thalassaemia/HbE, especially in splenectomised patients. This study demonstrated another abnormality of neutrophil function, namely neutrophil extracellular trap (NET) formation in splenectomised and non-splenectomised ß-thalassaemia/HbE patients who had iron overload. A classification system of morphological NET formation using confocal microscopy was developed, and samples were categorized into early and late phases which were subdivided into web-like and non-web structures. At baseline, neutrophils from non-splenectomised patients (58 ± 4%) and splenectomised patients (65 ± 3%) had higher early phase NETs than those from normal subjects (33 ± 1%). As a mimic of iron overload and infection, haemin/PMA/LPS treatment led to a significant reduction of early NETs and an increase of late NETs in neutrophils from normal and non-splenectomised patients. Interestingly, neutrophils from splenectomised patients had impaired development of late NETs. This suggests that during infection bacteria might not be trapped and may spread from the site of infection resulting in higher susceptibility to severe bacterial infection in splenectomised patients.

Pneumococcal vaccination for splenectomized patients with thalassemia major in Indonesia.

INTRODUCTION: Streptococcus pneumoniae is a capsulated bacterium that can cause severe infection in patients with thalassemia major, particularly those who have undergone splenectomy. The absence of the spleen as well as zinc deficiency in splenectomized patients with thalassemia major increases the possibility of developing invasive pneumococcal infection. The aims of this study are to evaluate pneumococcal IgG levels following PCV and PPV immunizations and the effect of zinc supplementation on qualitative specific immune responses in splenectomized patients with thalassemia. METHODS: Splenectomized patients with thalassemia major were administered a PCV pneumococcal vaccine (Prevenar 13®) at the start of the trial, after which they were randomly assigned to 2 groups (zinc and placebo group). After 8weeks, the patients received a PPV pneumococcal vaccine (Pneumovax®). Zinc syrup was provided to the zinc group at a dose of 1.5mg/kg/day (maximum of 50mg/day). Pneumococcal IgG examinations were conducted at the start of the trial and after 12weeks. RESULTS: In the group without PPV, the median initial pneumococcal IgG value was 315 (ranging from 65 to 1419) mU/mL for the zinc group and 338.5 (ranging from 82 to 1648) mU/mL for the placebo group. The median final pneumococcal IgG value was 1812.5 (ranging from 834 to 2444) mU/mL for the zinc group and 2857.5 (ranging from 834 to 2624) for the placebo group. The increase in the pneumococcal IgG value between the two groups was comparable (p=0.642). In the group with previous PPV, the median initial pneumococcal IgG value was 1333 (ranging from 793 to 2031) mU/mL for the zinc group and 880 (ranging from 74 to 1686) mU/mL for the placebo group. The median final pneumococcal IgG value was 1487 (ranging from 635 to 1757) mU/mL for the zinc group and 1012 (ranging from 292 to 1732) mU/mL for the placebo group. The increase in the pneumococcal IgG value between the two groups was comparable (p=0.528). CONCLUSION: There is no difference in the increase in pneumococcal IgG level in splenectomized patients with thalassemia major prior to and after receiving PPV. There were no differences observed in the development of pneumococcal IgG following zinc supplementation.

Fatal arteritis due to Pythium insidiosum infection in patients with thalassaemia.

Six thalassaemic patients had a distinct clinical syndrome characterized by progressive ischemia of the lower extremities, with ascending arteritis and thrombosis of the main arteries of the lower limbs. With periodic acid Schiff and Gomori's methenamine silver staining a large number of hyphae were revealed in the arterial wall and the outer part of the thrombus. Pythium insidiosum was isolated from 3 patients. The clinical course of the disease was progressive gangrene of the extremities and the patients invariably died when the infectious process reached the bifurcation of the aorta. There is no effective antimicrobial agent for the syndrome and radical amputation was the only method to ensure survival of the patients. P. insidiosum infection should be considered in thalassaemic patients with leg ulcers or arterial occlusion of the lower limbs.

Bacterial infection in patients with transfusion-dependent beta-thalassemia in central Taiwan.

The microorganisms, outcome of infections and the risk factors were evaluated in 39 patients with beta-thalassemia who received frequent blood transfusions. Among these patients, thirteen developed 22 episodes of infections, and bacteremia accounted for 72.7% (16/22) of all infections. Three patients developed meningitis, two patients had liver abscesses, three patients had soft tissue infections, one patient had a urinary tract infection and one patient had lobar pneumonia. Interestingly, a large proportion of the patients were infected by Gram-negative bacteria. Patients who were implanted with intravascular catheters were most susceptible to bacterial infection (1.70 episodes/patient) (P = 0.0069). So were patients with ferritin levels over 2,000 ng/mL (1.18 episodes/patient) (P = 0.028). The frequency of bacterial infections in patients with splenectomies (1.08 episode/patient) was also significantly higher than that of the average patient (P = 0.025). In conclusion, three major risk factors for bacterial infection were identified in this group of patients: intravascular catheterization, high serum ferritin levels (> or = 2,000 ng/mL) and splenectomy. The infection rate of these patients (0.45 episode/100 patient-year) is about 20-fold higher than that of general pediatric patients (0.023 episode/100 patient-year).

Oral Candida flora in a group of Jordanian patients with beta-thalassemia major.

OBJECTIVE: Thalassemic patients present with multiple immune abnormalities that may predispose them to oral Candida, however this has not been investigated. The aim of this study was to assess oral candidal colonization in a group of patients with beta-thalassemia major both qualitatively and quantitatively. STUDY DESIGN: The oral mycologic flora of 50 beta-thalassemia major patients and 50 age- and sex-matched control subjects was assessed using the concentrated oral rinse technique. Candida species were identified using the germ tube test and the Vitek yeast identification system. RESULTS: Oral Candida was isolated from 37 patients (74%) and 28 healthy subjects (56%; P = .04). The mean candidal count was significantly higher in thalassemic patients compared with the healthy group (P < .05) and in patients who had surgical splenectomy compared with nonsplenectomized patients (P = .04). CONCLUSION: Oral Candida colonization and candidal counts are significantly higher in beta-thalassemia major patients than in healthy subjects. Surgical splenectomy may increase the quantity of colonizing oral candidal organisms in thalassemic patients.

Infection due to Yersinia enterocolitica in a series of patients with beta-thalassemia: incidence and predisposing factors.

Over 15 years, 14 patients with yersiniosis in two North American comprehensive thalassemia clinics (0.6 cases per 100 patient-years) presented with fever (100%), diarrhea (86%), right-lower-quadrant abdominal pain (71%), bacteremia (57%), a palpable abdominal mass (36%), and pharyngitis (28%). Clinically apparent infection occurred within 10 days of blood transfusion in 57% of patients. Nine patients (64%) had only a modest elevation in serum level of ferritin (< 2,000 micrograms/L). Patients with focal abdominal findings had a higher body iron burden, as estimated by the serum ferritin level, and significant intraabdominal suppurative complications. Two patients were not receiving iron-chelating therapy with deferoxamine; one patient was receiving the experimental chelator deferiprone (L1). Iron-loaded patients with beta-thalassemia are at greatly increased risk for severe yersiniosis, even when their body iron burden (as indicated by the serum ferritin level) is only moderately elevated and they are not receiving iron-chelating therapy with deferoxamine.

Pneumococcal colonization in children with sickle cell disease [see comment].

OBJECTIVE: The goals of this prospective study were to define the Streptococcus pneumoniae colonization rate in children with sickle cell disease (SCD) at the Children's Hospital of Philadelphia and to determine the serotype and antibiotic susceptibility of all isolates. METHODS: Children with SCD followed at the hospital were sampled for colonization with S. pneumoniae by means of a throat or nasopharyngeal swab on one or two occasions. Patient information was obtained when the specimen was collected. Specimens were isolated on gentamicin-blood agar plates and modified Avery broth. Antibiotic susceptibility was determined by a commercially available test (E-test). Isolates were serotyped with the use of type-specific antisera. The relationship between the data noted above and certain clinical parameters was examined. RESULTS: A total of 490 specimens were obtained from 278 patients. Twenty-eight patients had a culture positive for S. pneumoniae, resulting in an overall colonization rate of 10%. Thirty-three percent (11/33) of all isolates were resistant to penicillin-seven intermediately resistant and four highly resistant. Twelve percent of isolates were also resistant to cefotaxime. Eight different serotypes were identified; all but one are included in the current 23-valent pneumococcal vaccine. Penicillin prophylaxis did not increase the rate of colonization with resistant strains of pneumococcus. CONCLUSION: Our results do not support a change in the current use of penicillin prophylaxis nor in the acute management of the febrile child with SCD.