Francis Jaubert

Evolution and expression of FOXL2

Mutations in the FOXL2 gene have recently been shown to cause the blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), a rare genetic disease (MIM 110100).1 In type I BPES eyelid abnormalities are associated with premature ovarian failure (POF), while in type II BPES only the eyelid malformation is observed.2 FOXL2 is the first human autosomal gene whose dominant mutations have been shown to be involved in POF. The eyelid malformation in both BPES types is inherited as a dominant trait and we have recently argued that ovarian failure in type II BPES is a recessive trait.3 FOXL2 is a single exon gene of 2.7 kb. The predicted protein of 376 amino acids belongs to the large family of forkhead/winged helix transcription factors, containing a characteristic 100 amino acid DNA binding forkhead domain. Many members are known to be involved in vertebrate embryogenesis4 and some have been implicated in inherited developmental human disorders.5 Apart from the forkhead domain, the FOXL2 protein also contains a polyalanine (poly-Ala) tract whose role has not yet been elucidated. Recurrent mutations leading to its expansion cause type II BPES and account for 30% of the deleterious alterations detected in the open reading frame (ORF).6,7 These alleles have been considered as hypomorphic (residual activity) in the context of the ovary.1,6 Northern blot analysis and RNA in situ hybridisation have shown that FOXL2 is expressed in developing mouse eyelids and in adult ovarian follicular cells.1 Here we have performed a comparative sequence analysis of FOXL2 in order to study the evolution of the FOXL2 coding region. We have estimated the synonymous (Ks) and non-synonymous (Ka) substitution rates in the ORF of several species, human, goat, mouse and pufferfish. In addition, to determine the subcellular localisation of the FOXL2 protein and its …

Dendritic cells are early cellular targets of Listeria monocytogenes after intestinal delivery and are involved in bacterial spread in the host

We studied the sequence of cellular events leading to the dissemination of Listeria monocytogenes from the gut to draining mesenteric lymph nodes (MLNs) by confocal microscopy of immunostained tissue sections from a rat ligated ileal loop system. OX‐62‐positive cells beneath the epithelial lining of Peyers patches (PPs) were the first Listeria targets identified after intestinal inoculation. These cells had other features typical of dendritic cells (DCs): they were large, pleiomorphic and major histocompatibility complex class IIhi. Listeria were detected by microscopy in draining MLNs as early as 6 h after inoculation. Some 80–90% of bacteria were located in the deep paracortical regions, and 100% of the bacteria were present in OX‐62‐positive cells. Most infected cells contained more than five bacteria each, suggesting that they had arrived already loaded with bacteria. At later stages, the bacteria in these areas were mostly present in ED1‐positive mononuclear phagocytes. These cells were also infected by an actA mutant defective in cell‐to‐cell spreading. This suggests that Listeria are transported by DCs from PPs to the deep paracortical regions of draining MLNs and are then transmitted to other cell populations by mechanisms independent of ActA. Another pathway of dissemination to MLNs was identified, probably involving free Listeria and leading to the infection of ED3‐positive mononuclear phagocytes in the subcapsular sinus and adjacent paracortical areas. This study provides evidence that DCs are major cellular targets of L. monocytogenes in PPs and that DCs may be involved in the early dissemination of this pathogen. DCs were not sites of active bacterial replication, making these cells ideal vectors of infection.

Attenuated virulence of Streptococcus agalactiae deficient in D-alanyl-lipoteichoic acid is due to an increased susceptibility to defensins and phagocytic cells

D‐alanylation of lipoteichoic acid (LTA), allows Gram‐positive bacteria to modulate their surface charge, regulate ligand binding and control the electromechanical properties of the cell wall. In this study, the role of D‐alanyl LTA in the virulence of the extracellular pathogen Streptococcus agalactiae was investigated. We demonstrate that a DltA– isogenic mutant displays an increased susceptibility to host defence peptides such as human defensins and animal‐derived cationic peptides. Accordingly, the mutant strain is more susceptible to killing by mice bone marrow‐derived macrophages and human neutrophils than the wild‐type strain. In addition, the virulence of the DltA– mutant is severely impaired in mouse and neonatal rat models. This mutant was eliminated more rapidly than the wild‐type strain from the lung of three‐week‐old mice inoculated intranasally and, consequently, is unable to induce a pneumonia. Finally, after intravenous injection of three‐week‐old mice, the survival of the DltA– mutant is markedly reduced in the blood in comparison to that of the wild‐type strain. We hypothesize that the decreased virulence of the DltA– mutant is a consequence of its increased susceptibility to cationic antimicrobial peptides and to killing by phagocytes. These results demonstrate that the D‐alanylation of LTA contributes to the virulence of S. agalactiae.

Aetiological diagnosis of male sex ambiguity: a collaborative study

Abstract. A collaborative study, supported by the Biomed2 Programme of the European Community, was initiated to optimise the aetiological diagnosis in genetic or gonadal males with intersex disorders, a total of 67 patients with external sexual ambiguity, testicular tissue and/or a XY karyotype. In patients with gonadal dysgenesis or true hermaphroditism, the incidence of vaginal development was 100%, a uterus was present in 60%; uni or bilateral cryptorchidism was seen in nearly all cases of testicular dysgenesis (99%) but in only 57% of true hermaphrodites. Mean serum levels of anti-müllerian hormone and of serum testosterone response to chorionic gonadotropin stimulation were significantly decreased in both conditions, by comparison with patients with unexplained male pseudohermaphroditism or partial androgen insensitivity (PAIS). Mutations in the androgen receptor, 90% within exons 2–8, were detected in patients with PAIS. Clinically, a vaginal pouch was present in 90%, cryptorchidism in 36%. In 52% of cases, no diagnosis could be reached, despite an exhaustive clinical and laboratory work-up, including routine sequencing of exons 2–8 of the androgen receptor. By comparison with PAIS, unexplained male pseudohermaphroditism was characterised by a lower incidence of vaginal pouch (55%) and cryptorchidism (22%) but a high incidence of prematurity/intrauterine growth retardation (30%) or mild malformations (14%). Conclusion: reaching an aetiological diagnosis in cases of male intersex is difficult because of the variability of individual cases. Hormonal tests may help to discriminate between partial androgen insensitivity and gonadal dysgenesis/true hermaphroditism but are of less use for differentiating from unexplained male pseudohermaphroditism. Sequencing of exons 2–8 of the androgen receptor after study of testosterone precursors following human chorionic gonadotrophin stimulation is recommended when gonadal dysgenesis and true hermaphroditism can be excluded.

Partial or near-total pancreatectomy for persistent neonatal hyperinsulinaemic hypoglycaemia: the pathologist's role.

Aims: To determine whether the presence of abnormal B‐cell nuclei predicts the existence of a focal or of a diffuse form of persistent neonatal and infantile hyperinsulinaemic hypoglycaemia in a series of 20 infants.

Contiguous Gene Deletion within Chromosome Arm 10q Is Associated with Juvenile Polyposis of Infancy, Reflecting Cooperation between the BMPR1A and PTEN Tumor-Suppressor Genes

We describe four unrelated children who were referred to two tertiary referral medical genetics units between 1991 and 2005 and who are affected with juvenile polyposis of infancy. We show that these children are heterozygous for a germline deletion encompassing two contiguous genes, PTEN and BMPR1A. We hypothesize that juvenile polyposis of infancy is caused by the deletion of these two genes and that the severity of the disease reflects cooperation between these two tumor-suppressor genes.

Airway remodeling is correlated with obstruction in children with severe asthma.

Background:  Severe asthma may involve an irreversible obstructive pattern, and structural changes in bronchial airways are believed to play a key role in this context. The aim of the present study was to compare airway remodeling in severe asthmatic children with or without obstructive pattern.

Expansion of Regulatory T Cells in Patients with Langerhans Cell Histiocytosis

Background Langerhans cell histiocytosis (LCH) is a rare clonal granulomatous disease that affects mainly children. LCH can involve various tissues such as bone, skin, lung, bone marrow, lymph nodes, and the central nervous system, and is frequently responsible for functional sequelae. The pathophysiology of LCH is unclear, but the uncontrolled proliferation of Langerhans cells (LCs) is believed to be the primary event in the formation of granulomas. The present study was designed to further investigate the nature of proliferating cells and the immune mechanisms involved in the LCH granulomas. Methods and Findings Biopsies (n = 24) and/or blood samples (n = 25) from 40 patients aged 0.25 to 13 y (mean 7.8 y), were studied to identify cells that proliferate in blood and granulomas. We found that the proliferating index of LCs was low (∼1.9%), and we did not observe expansion of a monocyte or dendritic cell compartment in patients. We found that LCH lesions were a site of active inflammation, tissue remodeling, and neo-angiogenesis, and the majority of proliferating cells were endothelial cells, fibroblasts, and polyclonal T lymphocytes. Within granulomas, interleukin 10 was abundant, LCs expressed the TNF receptor family member RANK, and CD4+ CD25high FoxP3high regulatory T cells (T-regs) represented 20% of T cells, and were found in close contact with LCs. FoxP3+ T-regs were also expanded compared to controls, in the blood of LCH patients with active disease, among whom seven out of seven tested exhibited an impaired skin delayed-type hypersensitivity response. In contrast, the number of blood T-regs were normal after remission of LCH. Conclusions These findings indicate that LC accumulation in LCH results from survival rather than uncontrolled proliferation, and is associated with the expansion of T-regs. These data suggest that LCs may be involved in the expansion of T-regs in vivo, resulting in the failure of the host immune system to eliminate LCH cells. Thus T-regs could be a therapeutic target in LCH.

Bronchial casts in children with cardiopathies: the role of pulmonary lymphatic abnormalities.

Expectoration of bronchial casts, a condition also called plastic bronchitis, is very rare in children. Bronchial casts may be associated with bronchopulmonary diseases associated with mucus hypersecretion, bronchopulmonary bacterial infections, congenital and acquired cardiopathies, or pulmonary lymphatic abnormalities. A classification based on anatomy and pathology has been proposed which identifies an “acellular” group associated with congenital cardiopathies and palliative surgery.

Mutational, functional, and expression studies of the TCF4 gene in Pitt-Hopkins syndrome.

Pitt‐Hopkins syndrome is a severe congenital encephalopathy recently ascribed to de novo heterozygous TCF4 gene mutations. We report a series of 13 novel PHS cases with a TCF4 mutation and show that EEG, brain magnetic resonance imagain (MRI), and immunological investigations provide valuable additional clues to the diagnosis. We confirm a mutational hot spot in the basic domain of the E‐protein. Functional studies illustrate that heterodimerisation of mutant TCF4 proteins with a tissue‐specific transcription factor is less effective than that homodimerisation in a luciferase reporter assay. We also show that the TCF4 expression pattern in human embryonic development is widespread but not ubiquitous. In summary, we further delineate an underdiagnosed mental retardation syndrome, highlighting TCF4 function during development and facilitating diagnosis within the first year of life. Hum Mutat 0, 1–8, 2009.