Tore G. Abrahamsen

Clinical spectrum of X-linked hyper-IgM syndrome

We report the clinical and immunologic features and outcome in 56 patients with X-linked hyper-IgM syndrome, a disorder caused by mutations in the CD40 ligand gene. Upper and lower respiratory tract infections (the latter frequently caused by Pneumocystis carinii), chronic diarrhea, and liver involvement (both often associated with Cryptosporidium infection) were common. Many patients had chronic neutropenia associated with oral and rectal ulcers. The marked prevalence of infections caused by intracellular pathogens suggests some degree of impairment of cell-mediated immunity. Although lymphocyte counts and in vitro proliferation to mitogens were normal, a defective in vitro proliferative response to antigens was observed in some patients, and additional defects of cell-mediated immunity may be presumed on the basis of current knowledge of CD40-ligand function. All patients received regular infusions of immunoglobulins. Four patients underwent liver transplantation because of sclerosing cholangitis, which relapsed in there. Three patients underwent bone marrow transplantation. Thirteen patients (23%) died of infection and/or liver disease. X-linked hyper-IgM syndrome, once considered a clinical variant of hypogammaglobulinemia, is a severe immunodeficiency with significant cellular involvement and a high mortality rate.

Late-Onset Septicemia in a Norwegian National Cohort of Extremely Premature Infants Receiving Very Early Full Human Milk Feeding

Objectives. To investigate the occurrence of and risk factors for late-onset septicemia (LOS) in a national cohort of extremely premature infants who received very early full human milk feeding. Methods. A prospective study of all infants born in Norway in 1999 and 2000 with gestational age of <28 weeks or birth weight of <1000 g was performed. Extensive clinical information, including data on feeding practices and episodes of septicemia, was collected on predefined forms. LOS was defined as growth of bacteria or fungi in blood cultures in conjunction with clinical symptoms consistent with systemic infection occurring after day 6 of life. Cox regression models, including models allowing for time-dependent covariates, were applied in the analysis of LOS. Results. Of 464 eligible infants, 462 (99.6%) were enrolled and 405 (87.7%) survived until day 7. LOS was diagnosed for 80 (19.7%). The predominant pathogens were coagulase-negative staphylococci, followed by Candida spp. Case fatality rates associated with septicemia were 10% in general and 43% for Candida spp septicemia. Necrotizing enterocolitis or bowel perforation was diagnosed for 19 infants (4%). Enteral feeding with human milk was initiated within the third day for 98% of patients, and 92% were receiving full enteral feeding (FEF) with human milk within the third week. Both high Clinical Risk Index for Babies scores and an umbilical venous catheter in situ at 7 days of age significantly predicted LOS. However, the overall most influential risk factor for LOS was the number of days without establishment of FEF with human milk, with an adjusted relative risk of 3.7 (2.0–6.9) for LOS if FEF was not established within the second week of life. Conclusions. The incidence and case fatality rate of septicemia for this cohort of extremely preterm infants were lower than values in comparable studies. The main difference, compared with other studies, was the feeding practice, and the data suggest that very early FEF with human milk significantly reduces the risk of LOS among extremely premature infants.

Elution and Characterization of Lymphocytes from Rheumatoid Inflammatory Tissue

Lymphocytes were eluted from the synovial tissue of 19 patients with classical rheumatoid arthritis. The tissue was minced and dissociated by treatment with crude collagenase and DNase, The cell suspension obtained was filtered and incubated in plastic culture flasks overnight at 37°C, The cells that did not adhere to the plastic surface were harvested and the lymphocytes further purified by the Ficoll‐Isopaque gradient centrifugation technique. The lymphocyte yield varied from 0.64 to 32 × 106 cells. Differential counts showed on the average 85% lymphocytes, 12% macrophage‐like cells, and variable proportions of polymorphonuclear granulocytes, unclassified cells, and dead cells. An average of 77% of the cells were viable as assessed by the trypan blue exclusion test. This cell suspension was investigated for lymphocyte populations, T lymphocytes were predominant in all experiments (mean, 73.6%), The mean percentage of B lymphocytes was 9.7%, whereas the proportion of Fc‐receptor‐bearing lymphocytes was on the average 6.0%,

Primary Immunodeficiency Diseases in Norway

This study represents the first national epidemiological survey of primary immunodeficiency diseases in Norway. Uniform questionnaires were sent out in April 1998 to all hospital departments considered relevant. As of February 1999, a total of 372 patients have been registered, of whom 69 patients are deceased. With a population of 4.45 million people, the total prevalence of primary immunodeficiency diseases in Norway February 1, 1999 is 6.82 per 100.000 inhabitants. Distribution between the main immunodeficiency diagnoses is (a) antibody deficiencies 50.8%, (b) combined deficiencies included other immunodeficiency syndromes 12.4%, (c) complement deficiencies 21.0%, (d) phagocytic disorders 6.7%, (e) and immunodeficiency associated with other congenital diseases 9.1%. Compared to previous reports from other European countries, there is a smaller proportion of antibody deficiencies due to few IgA deficiencies registered and a large proportion of complement deficiencies due to many patients with hereditary angioedema.

Molecular Epidemiology of Aspergillus fumigatus Isolates Recovered from Water, Air, and Patients Shows Two Clusters of Genetically Distinct Strains

ABSTRACT There has been an increase in data suggesting that besides air, hospital water is a potential source of transmission of filamentous fungi, and in particular Aspergillus fumigatus. Molecular characterization of environmental and clinical A. fumigatus isolates, collected prospectively during an 18-month period, was performed to establish if waterborne fungi play a role in the pathogenesis of invasive aspergillosis. Isolates recovered from water (n = 54) and air (n = 21) at various locations inside and outside the hospital and from 15 patients (n = 21) with proven, probable, or possible invasive aspergillosis were genotyped by amplified fragment length polymorphism analysis. Based on genomic fingerprints, the environmental A. fumigatus isolates could be grouped into two major clusters primarily containing isolates recovered from either air or water. The genotypic relatedness between clinical and environmental isolates suggests that patients with invasive aspergillosis can be infected by strains originating from water or from air. In addition, 12 clusters with genetically indistinguishable or highly related strains were differentiated, each containing two to three isolates. In two clusters, clinical isolates recovered from patients matched those recovered from water sources, while in another cluster the clinical isolate was indistinguishable from one cultured from air. This observation might open new perspectives in the development of infection control measures to prevent invasive aspergillosis in high-risk patients. The genetic variability found between airborne and waterborne A. fumigatus strains might prove to be a powerful tool in understanding the transmission of invasive aspergillosis and in outbreak control.

Human genetic deficiencies reveal the roles of complement in the inflammatory network: Lessons from nature

Complement component C5 is crucial for experimental animal inflammatory tissue damage; however, its involvement in human inflammation is incompletely understood. The responses to Gram-negative bacteria were here studied taking advantage of human genetic complement-deficiencies—natures own knockouts—including a previously undescribed C5 defect. Such deficiencies provide a unique tool for investigating the biological role of proteins. The experimental conditions allowed cross-talk between the different inflammatory pathways using a whole blood model based on the anticoagulant lepirudin, which does not interfere with the complement system. Expression of tissue factor, cell adhesion molecules, and oxidative burst depended highly on C5, mediated through the activation product C5a, whereas granulocyte enzyme release relied mainly on C3 and was C5a-independent. Release of cytokines and chemokines was mediated to varying degrees by complement and CD14; for example, interleukin (IL)-1β and IL-8 were more dependent on complement than IFN-γ and IL-6, which were highly dependent on CD14. IL-1 receptor antagonist (IL-1ra) and IFN-γ inducible protein 10 (IP-10) were fully dependent on CD14 and inversely regulated by complement, that is, complement deficiency and complement inhibition enhanced their release. Granulocyte responses were mainly complement-dependent, whereas monocyte responses were more dependent on CD14. Notably, all responses were abolished by combined neutralization of complement and CD14. The present study provides important insight into the comprehensive role of complement in human inflammatory responses to Gram-negative bacteria.

Coagulase-negative staphylococcal sepsis in neonates. Association between antibiotic resistance, biofilm formation and the host inflammatory response.

Background: Coagulase-negative staphylococci (CoNS) are the most prevalent pathogens causing late onset sepsis in neonates. They are often multiresistant to antibiotics, and the ability to form biofilm is considered their main virulence determinant. Methods: During a 12-year period, we identified 150 neonates having 164 suspected septic episodes with growth of CoNS in blood culture. We examined the relationship between antibiotic resistance, phenotypic biofilm production and genetic determinants for biofilm formation in different CoNS species and their correlation with neonatal inflammatory response. Results: Eighty-five episodes were classified as true sepsis, and 79 episodes of CoNS growth in blood culture were considered contaminations. Sixty-one percent of Staphylococcus epidermidis isolates produced biofilm compared with 26% of CoNS non-epidermidis (P < 0.001). We observed no difference in phenotypic biofilm production or genetic determinants for biofilm formation between invasive isolates and contaminants. C-reactive protein levels as a marker of inflammatory response were higher in CoNS sepsis caused by methicillin and aminoglycoside resistant versus susceptible isolates (P = 0.031). In contrast, there was a significant association between a lower C-reactive protein response and biofilm-positive isolates (P = 0.018). Antibiotic resistance was significantly correlated with biofilm production in S. epidermidis, but not in other CoNS species. Conclusions: CoNS sepsis with biofilm-forming strains was associated with a decreased host inflammatory response, potentially limiting the immune system to counteract the infection. The impact of antibiotic resistance and virulence determinants on clinical outcome of neonatal CoNS sepsis warrants additional clinical studies.

Incidence and characteristics of arthritis in Norwegian children: a population-based study.

OBJECTIVE. The purpose of this work was to assess the annual incidence of arthritis in children and describe early disease and patient characteristics, microbiologic features, and immunogenetic factors in children with different subgroups of childhood arthritis. PATIENTS AND METHODS. A population-based multicenter study was performed in southeastern Norway between June 1, 2004, and May 31, 2005. The total population of children under 16 years of age was 255303. Physicians were asked to refer their patients with suspected arthritis to the local department of pediatrics or rheumatology. The children were assessed on the basis of clinical, radiologic, and laboratory examinations at inclusion and followed up at 6 weeks, 6 months, and thereafter as long as clinically indicated. A chart review was performed to identify patients with arthritis who had not been included prospectively. RESULTS. The total annual incidence of arthritis was 71 per 100000 children. Transient arthritis, juvenile idiopathic arthritis, postinfectious arthritis, and infectious arthritis were found in 43, 14, 9, and 5 of 100000 children, respectively. The incidence was higher in children under the age of 8 years than in older children (107 vs 34 per 100000). Arthritis occurred more frequently in boys than in girls before the age of 8 years but not thereafter. The median age of onset was lower in children with infectious arthritis than in those with other types of arthritis. Monarthritis was less frequent in patients with juvenile idiopathic arthritis than in the other subgroups (64% vs 83%–100%). Ten percent of the patients had poststreptococcal reactive arthritis, and only 1 had enteropathic arthritis. Autoantibodies and the presence of HLA-B27 were associated with juvenile idiopathic arthritis. CONCLUSIONS. The annual incidence of childhood arthritis was 71 per 100000 children. We found several factors that may help in differentiating between subgroups of arthritis.

Septicemia in the first week of life in a Norwegian national cohort of extremely premature infants.

Objectives. To investigate the incidence, causes, predictors, and outcomes of septicemia in the first week of life in a national cohort of extremely premature infants. Methods. A prospective study of survival of all infants with gestational age of <28 weeks or birth weight of <1000 g who were born in Norway in 1999–2000 was performed. Data on the maternal prenatal history, delivery, and neonatal course, including detailed information on episodes of microbiologically verified septicemia, were collected on predefined forms. Septicemia was reported in 2 groups, ie, episodes diagnosed on the day of delivery (ie, very early-onset septicemia [VEOS]) and episodes diagnosed from day 2 to day 7 of life (ie, early-onset septicemia [EOS]). Logistic regression models were used for the selection of variables for predictor analysis in each group. Results. Of 462 included infants, VEOS occurred for 15 (32.5 per 1000 population) and EOS for 15 (35.5 per 1000 population). The most prevalent bacteria were Escherichia coli in VEOS (n = 9) and staphylococci (coagulase-negative staphylococci and Staphylococcus aureus) (n = 15) in EOS. Case fatality rates were 40% and 13%, respectively. Independent predictive factors for VEOS were clinical chorioamnionitis (odds ratio [OR]: 10.5; 95% confidence interval [CI]: 3.3-33.4) and high maternal age (OR: 1.2; 95% CI: 1.0–1.3), whereas not receiving systemic antibiotic therapy within 2 days of age (OR: 13.6; 95% CI: 3.7–50.2) and receiving nasal continuous positive airway pressure (n-CPAP) support at 24 hours of age (OR: 9.8; 95% CI: 2.5–38.4) independently predicted septicemia after the first day of life. Conclusions. Whereas vertically transmitted septicemia was dominated by Gram-negative bacteria, with predictors being exclusively of maternal origin, EOS was dominated by typically nosocomial flora, with n-CPAP treatment at 24 hours of age being a powerful predictor. Early n-CPAP treatment, as opposed to mechanical ventilation, as a powerful predictor of septicemia in the early neonatal period, even with adjustment for early systemic antibiotic treatment, is a new observation among extremely premature infants that warrants additional study.

TTC7A mutations disrupt intestinal epithelial apicobasal polarity

Multiple intestinal atresia (MIA) is a rare cause of bowel obstruction that is sometimes associated with a combined immunodeficiency (CID), leading to increased susceptibility to infections. The factors underlying this rare disease are poorly understood. We characterized the immunological and intestinal features of 6 unrelated MIA-CID patients. All patients displayed a profound, generalized lymphocytopenia, with few lymphocytes present in the lymph nodes. The thymus was hypoplastic and exhibited an abnormal distribution of epithelial cells. Patients also had profound disruption of the epithelial barrier along the entire gastrointestinal tract. Using linkage analysis and whole-exome sequencing, we identified 10 mutations in tetratricopeptide repeat domain–7A (TTC7A), all of which potentially abrogate TTC7A expression. Intestinal organoid cultures from patient biopsies displayed an inversion of apicobasal polarity of the epithelial cells that was normalized by pharmacological inhibition of Rho kinase. Our data indicate that TTC7A deficiency results in increased Rho kinase activity, which disrupts polarity, growth, and differentiation of intestinal epithelial cells, and which impairs immune cell homeostasis, thereby promoting MIA-CID development.