Identification, activation, and selective in vivo ablation of mouse NK cells via NKp46

Natural killer (NK) cells contribute to a variety of innate immune responses to viruses, tumors and allogeneic cells. However, our understanding of NK cell biology is severely limited by the lack of consensus phenotypic definition of these cells across species, by the lack of specific marker to visualize them in situ, and by the lack of a genetic model where NK cells may be selectively ablated. NKp46/CD335 is an Ig-like superfamily cell surface receptor involved in human NK cell activation. In addition to human, we show here that NKp46 is expressed by NK cells in all mouse strains analyzed, as well as in three common monkey species, prompting a unifying phenotypic definition of NK cells across species based on NKp46 cell surface expression. Mouse NKp46 triggers NK cell effector function and allows the detection of NK cells in situ. NKp46 expression parallels cell engagement into NK differentiation programs because it is detected on all NK cells from the immature CD122(+)NK1.1(+)DX5(-) stage and on a minute fraction of NK-like T cells, but not on CD1d-restricted NKT cells. Moreover, human NKp46 promoter drives NK cell selective expression both in vitro and in vivo. Using NKp46 promoter, we generated transgenic mice expressing EGFP and the diphtheria toxin (DT) receptor in NK cells. DT injection in these mice leads to a complete and selective NK cell ablation. This model paves a way for the in vivo characterization and preclinical assessment of NK cell biological function.

Nucleic acid agonists for Toll-like receptor 7 are defined by the presence of uridine ribonucleotides

Toll-like receptor 7 (TLR7) mediates innate responses by responding to viral RNA in endocytic compartments. However, the molecular pattern recognised by TLR7 and whether it differs between RNA of viral and self origin remains unclear. Here, we identify nucleic acids that act as TLR7 agonists for mouse and human cells. We show that uridine and ribose, the two defining features of RNA, are both necessary and sufficient for TLR7 stimulation, and that short single-stranded RNA (ssRNA) act as TLR7 agonists in a sequence-independent manner as long as they contain several uridines in close proximity. Consistent with the notion that TLR7 lacks specificity for sequence motifs, we show that it is triggered equally efficiently by viral or self RNA delivered to endosomes. Our results support the notion that TLR7 recognises uracil repeats in RNA and that it discriminates between viral and self ligands on the basis of endosomal accessibility rather than sequence.

Cosegregation of a novel homozygous CYP11B1 mutation with the phenotype of non-classical congenital adrenal hyperplasia in a consanguineous family

We report a novel missense mutation of CYP11B1 causing non-classical 11beta-hydroxylase deficiency in 3 members of a consanguineous Turkish family. Two siblings presented with clinical evidence of precocious pseudopubarche. Biochemistry suggested 11beta-hydroxylase deficiency and genetic analysis revealed that they were homozygous for the missense mutation L489S within exon 9 of the CYP11B1 gene. The unaffected parents were heterozygotes for the same mutation. In addition, a paternal aunt of the affected siblings presenting with primary infertility and mild hirsutism was found to have the same homozygous mutation. This is the first report of a homozygous mutation in non-classical congenital adrenal hyperplasia that cosegregates with clinical phenotype. The significance of the missense mutation L489S in CYP11B1 is further supported by the conservation of leucine at position 489 in CYP11 genes in eleven other species. Molecular modelling of the enzyme suggests that the mutation L489S in CYP11B1 may alter the enzyme's substrate-binding affinity. These findings suggest that this homozygous mutation affects 11beta-hydroxylase function, resulting in the clinical features of non-classical adrenal hyperplasia in this family.

Bilateral anorchia in infancy: occurence of micropenis and the effect of testosterone treatment

OBJECTIVE

To analyze the clinical and histological findings in boys with bilateral anorchia and the response to testosterone treatment on penis length.

STUDY DESIGN

Patients were divided into two groups according to the absence (group A, n = 29) or the presence (group B, n = 26) of palpable intrascrotal or inguinal mass at first clinical examination.

RESULTS

A micropenis was found in 46% of patients (n = 24) with a similar proportion in both groups. Testosterone treatment induced a mean penis length gain of 1.9 +/- 1.3 SDS (standard deviation score). However, micropenis persisted in six patients. Histological examination (n = 18) confirmed the absence of any testicular structure with deferent ducts being present unilaterally or bilaterally in all but three patients. In these three patients, a hemorrhagic testis, probably as a result of a mechanical torsion, was found.

CONCLUSIONS

The presence of isolated micropenis in almost half of patients with bilateral anorchia strongly suggests that the testicular damage frequently occurs during the second half of gestation after male sexual differentiation. In most cases, testosterone treatment stimulates the penile growth. Although the pathogenesis of bilateral anorchia may be heterogeneous, our study suggests that gonads may have been functionally abnormal before they disappeared, and suggests that some patients have an intrinsic endocrine disorder.

[Clinical and tomographic aspects of 29 cases of phakomatosis in Guinea]

The purpose of this report is to describe 29 cases of phakomatosis including 18 cases of tuberous sclerosis (Bourneville) and 11 cases of neurofibromatosis (von Recklinghausen) observed over a 10-year period at the Neurology Department of the University Hospital Centre in Conakry, Guinea. Findings during this period were consistent with those classically reported in the literature: high frequency of advanced skin lesions coalescing into massive tumours, occurrence of seizures of all types and development of a wide variety of complications as a result of late diagnosis. Our experience underscores the need for follow-up and surveillance of these patients by somatic studies based on neurological, ophthalmologic and tomographic data depending on clinical findings.

[Histological and molecular study of fetal human adrenal cortex (12-36 wk)]

Histological and functional characteristics of the fetal human adrenals was studied in 119 normal fetuses aged 12 to 36 weeks development (WD). Immunocytochemical detection of steroidogenesis enzyme (3beta-HSD and P450 c21) and evaluation of cell proliferation using two nuclear markers (Ki-67 and PCNA) were performed in 70 of them. The human fetal adrenal cortex is composed of two morphologically distinct zones: the definitive peripheral zone and the fetal inner zone. From the 12th WD, we observed expression of an adherence protein (NCAM) and two steroidogenesis enzymes (3beta-HSD and P450 c21) in the definitive zone cells, attesting to the capacity of these cells to synthesize mineralocorticoids and/or cortisol. In the fetal zone, only P450 c21 immunoreactivity was detected. From the 14th WD, a transitional zone between the definitive zone and the fetal zone was identified by immunocytochemistry, with expression of 3b-HSD from the 21st WD. Only cells of the definitive zone proliferated from the 12th to 25th WD. The indexes of proliferation of PCNA and Ki-67, 40% and 25% respectively, decreased gradually and were lower than 1% at the 25th WD.

[Adrenal hypoplasia congenita: four new cases in children]

Adrenal hypoplasia congenita (AHC) is an extremely uncommon disease of early onset. This condition can be lethal in the absence of adapted treatment. Some of these diseases are related to changes in the gene DAX1 that encodes a member of the superfamily of hormone nuclear receptors. It is a transcriptional repressor that is central in the morphogenesis of the adrenals and the gonadic differentiation. Here we report on four cases of X- linked AHC. In the first two familial cases, mutations were identified and mothers were heterozygotes. Abnormally low levels of estriol were evidenced during the pregnancy leading to an early diagnosis and adapted care of the affected male neonates. These children are doing well with a 21-and 20 months follow-up with hormone replacement at the present time. The two last cases corresponded to a contiguous gene syndrome associating AHC to glycerol-kinase deficiency that was revealed respectively at six days and seven years of age by acute adrenal insufficiency.

Le développement de la surrénale humaine

The human adrenal is an endocrine gland located at the superior part of the kidney. Composed of the adrenal cortex of mesoblastic origin and the adrenal medulla of neuroectoblastic origin, the human fetal adrenal grows considerably during the first three months of development. From 12 to 18 weeks of development (WD), the weight of the adrenals increases seven-fold. The gland's weight doubles from 18 to 28 WD and from 28 to 36 WD. At birth, the two adrenals weigh on average 10 g. At the 8th week, two zones are individualized in the adrenal cortex: the definitive zone and the fetal inner zone. At the second trimester, according to ultrastructural and biochemical studies, a third zone, called the transition zone, is individualized between the definitive zone and the fetal inner zone. The definitive zone persists, but the origin of the three zones (glomerular, fascicular and reticular) of adult adrenal cortex is not known. The fetal inner zone regresses from the 5th month of gestation and disappears totally one year after birth. At the 8th week, the immature neuroblasts migrate to the definitive zone, then to the fetal inner zone to compose the adrenal medulla, which develops essentially after birth and during the first year. Before the 10th week, the human fetal adrenal is able to produce steroid hormones, in particular dehydroepiandrosterone sulfate (DHEA-S); the secretion of cortisol remains discussed. The development of the human fetal adrenal is complex and is under the control of hormones (ACTH, LH and betaHCG), growth factors (ACTH essentially) and transcription factors (essentially SF1 and DAX-1). Knowledge of morphological and molecular phenomena of this development permits to understand the pathophisiology of congenital adrenal deficiencies.

21-hydroxylase deficiency: an exemplary model of the contribution of molecular biology in the understanding and management of the disease

Congenital adrenal hyperplasia (CAH) is a family of autosomal recessive disorders caused by mutations in genes encoding the enzymes involved in one of the various steps of adrenal steroid synthesis. Steroid 21-hydroxylase deficiency (21-OHD) is responsible for over 95% of the 5 forms of CAH, and results due to enzymatic defect owing to mutation in the CYP21 gene. The disease has two major clinical presentations. The "classical" form is severe, and divided into a salt wasting (SW) and simple virilizing (SV) subgroups. In both, affected female fetuses undergo virilization of the external genitalia prenatally and present at birth with sexual ambiguity. In addition, in both sexes infants with SW CAH are at risk of life-threatening adrenal crisis without treatment. This is why it is so important to make a diagnosis and to counsel the families. The diagnosis is easy by measuring the plasma levels of 17-hydroxyprogesterone (17-OHP) in antenatal (amniotic fluid), or perinatal samples (peripheral blood). Confirmation by molecular genetic analysis is advised. The second form of 21-OHD is called "non classical" because the presentation is much less severe and the onset of clinical expression occurs long after birth, often in the peripubertal period, as non-specific symptoms of hyperandrogeny. The unambiguous diagnosis of the latter requires a simple short ACTH test, with the measurement of 17-OHP at 60 min. In both forms, the mutations on the gene CYP21 responsible for the disease are now well known and can be identified by molecular biology techniques. There is a good correlation between phenotypes and genotypes, due to variable amount of the 21-hydroxylase-enzyme activity left (null to 50-60%). SW, SV and NC forms are associated with distinct mutations or combination of mutations. Nowadays, by combining hormonal and molecular tests, it is possible to predict the clinical form of the disease in a given family in the context of a prenatal diagnosis, which can lead to a prenatal treatment. Therefore, 21-OHD genotyping also appears essential for a new approach of genetic counseling, prediction of clinical form after postnatal screening and to define the post-ACTH 17-OHP values indicating the cut-off lines between NC, heterozygote and normal subjects.

Phosphostim-activated gamma delta T cells kill autologous metastatic renal cell carcinoma

Metastatic renal cell carcinoma, inherently resistant to conventional treatments, is considered immunogenic. Indeed, partial responses are obtained after treatment with cytokines such as IL-2 or IFN-alpha, suggesting that the immune system may control the tumor growth. In this study, we have investigated the ability of the main subset of peripheral gammadelta lymphocytes, the Vgamma9Vdelta2-TCR T lymphocytes, to induce an effective cytotoxic response against autologous primary renal cell carcinoma lines. These gammadelta T cells were expanded ex vivo using a Vgamma9Vdelta2 agonist, a synthetic phosphoantigen called Phosphostim. From 11 of 15 patients, the peripheral Vgamma9Vdelta2 T cells were amplified in vitro by stimulating PBMCs with IL-2 and Phosphostim molecule. These expanded Vgamma9Vdelta2 T cells express activation markers and exhibit an effector/memory phenotype. They display a selective lytic potential toward autologous primary renal tumor cells and not against renal NC. The lytic activity involves the perforin-granzyme pathway and is mainly TCR and NKG2D receptor dependent. Furthermore, an increased expression of MHC class I-related molecule A or B proteins, known ligands of NKG2D, are detected on primary renal tumor cells. Interestingly, from 2 of the 11 positive cultures in response to Phosphostim, expanded-Vgamma9Vdelta2 T cells present an expression of killer cell Ig-like receptors, suggesting their prior recruitment in vivo. Unexpectedly, on serial frozen sections from three tumors, we observe a gammadelta lymphocyte infiltrate that was mainly composed of Vgamma9Vdelta2 T cells. These results outline that Vgamma9Vdelta2-TCR effectors may represent a promising approach for the treatment of metastatic renal cell carcinoma.

[Wilson's disease: study of 6 neurologic forms observed at the University Hospital in Conakry]

This report describes 6 cases of Wilson's disease observed at the University Hospital Center in Conakry, Guinea. Presenting symptoms involved extrapyramidal syndrome in 4 cases, psychomotor epilepsy in 1, and confusional syndrome in 1 case. Diagnosis was based on neuropsychic manifestations, Kayser-Fleicher corneal ring, liver failure, and impaired copper metabolism. Brain CT-scan depicted normal features in 3 cases, symmetric hypodensity of the lenticular nucleus in one, discrete ventricular dilatation of in one a and cortico-subcoetical atrophy in one.

[Late occurrence of first epileptic seizures: a 42-case series]

Late occurrence of epilepsy is common in tropical areas. This report describes a series of 42 cases of late epilepsy collected over a three-year period. Findings were consistent with the literature: highest incidence in young age groups, predominance of partial symptomatic epilepsy, and wide spectrum of etiologies. The most frequent etiology was tumoral disease followed by vascular and infectious disease. Brain CT scan and electro-encephalography were highly useful for identification of clinical and etiological entities.

LIGHT, a new TNF superfamily member, is essential for memory T helper cell-mediated activation of dendritic cells

LIGHT is a recently identified member of the TNF superfamily that is up-regulated on activated T cells and can cooperate with CD40L to condition DC for the priming of CTL. In this report, we show that an intracellular pool of LIGHT is found selectively in some CD45RA-CD27+CD4+ "central" memory T cells and to a greater extent in some CD45RA-CD27-CD4+ effector memory T cells. LIGHT, like CD40L, is rapidly up-regulated on memory CD4+ T cells upon activation. Unlike CD40L, LIGHT up-regulation on naive T cells is delayed. Stimulation of DC with each subset of memory T cells in the presence of superantigen revealed that CD40L and LIGHT are required for optimal secretion of IL-12. Moreover, effector memory T cells, which can interact with DC in peripheral tissues, contribute to CCR7 induction on DC. LIGHT and CD40L can also regulate IL-12 production by CCR7+ DC capable of migration to lymph nodes. These data suggest that both LIGHT and CD40L may be involved in the maintenance or reactivation of secondary Th1 responses.

Follow-up of 68 children with congenital adrenal hyperplasia due to 21-hydroxylase deficiency: relevance of genotype for management

The phenotype of congenital adrenal hyperplasia (CAH) varies greatly. The purpose of this study was to optimize diagnosis and follow-up by comparing phenotype with genotype. Sixty-eight patients with CAH due to 21-hydroxylase deficiency were studied by clinical, hormonal, and molecular genetic methods. Patients were classified according to predicted mutation severity: group 0, null mutation (17.6%); group A, homozygous for IVS2 splice mutation or compound heterozygous for IVS2 and null mutations (33.8%); group B, homozygous or compound heterozygous for I172N mutation (14.7%); group C, homozygous or compound heterozygous for V281L or P30L mutations (26.5%); and group D, mutations with unknown enzyme activity (7.4%). All group 0 and A patients had the salt-wasting form, and group C had nonclassical forms. Group B included five salt-wasting and five simple virilizing forms. Groups 0 and A were younger at diagnosis (P < 0.02), and females were more virilized than those in group B. Group B had higher basal plasma 17-hydroxyprogesterone (564 +/- 162 nmol/liter) and testosterone (11 +/- 3 nmol/liter) levels than group C [59 +/- 13 nmol/liter (P < 0.001) and 1.4 +/- 0.2 nmol/liter (P < 0.005), respectively]. Hydrocortisone doses given to groups 0, A, and B were similar at all ages, but lower in group C (P < 0.01). Final height was below target height in classical (n = 16; -2 +/- 0.2 SD score; P < 0.02) and nonclassical (n = 11; -1.2 +/- 0.4 SD score; P < 0.03) forms. The severity of the genetic defects and the clinical-laboratory features are well correlated. Genotyping, combined with neonatal screening and optimal medical and surgical treatment, can help in the management of CAH.

Mechanisms regulating expression of the tumor necrosis factor-related light gene. Role of calcium-signaling pathway in the transcriptional control

LIGHT (TNFSF14) is a newly identified tumor necrosis factor superfamily member involved in the regulation of immune responses by control of activation, maturation, and survival of immune effector cells. Despite the immunological relevance of the LIGHT protein, little knowledge is available as to how light gene expression is regulated. In T-lymphocytes, most LIGHT surface expression and transcript accumulation occurs after T cell activation. In this study, we have shown that these events are blocked at the transcriptional level by cyclosporin A, an immuno-suppressive drug. Besides, we identified a role for Ca2+ -signaling pathways and NFAT transcription factors in T cell activation-induced LIGHT expression. To further investigate this process, we have identified, cloned, and characterized a 2.1-kilobase 5'-flanking DNA genomic fragment from the human light gene. We have shown the transcriptional activity of the herein-identified minimal 5' regulatory region of human light gene parallels the endogenous expression of light in T cells. Moreover, we demonstrated that induced LIGHT promoter activity can be equally blocked by cyclosporin A treatment or dominant negative NFAT overexpression and further identified by site-directed mutagenesis and electrophoretic mobility supershift analysis of a NFAT transcription factor binding site within the human light minimal promoter. Finally, Sp1 and Ets1 binding sites were identified and shown to regulate light basal promoter activity. Thus, the present study establishes a molecular basis to further understand the mechanisms governing human light gene expression and, consequently, could potentially lead to novel therapeutic manipulations that control the signaling cascade, resulting in LIGHT production in conditions characterized by immunopathologic activation of T cells.

[Atypical neurosyphilis: 28 cases observed at the University Hospital Center of Conakry]

This study describes a series of 28 cases of neurosyphylis presenting atypical oligosymptomatic syndromes involving epileptic attack, chronic headache, peripheral facial paralysis, deafness, isolated optic atrophy, and cerebral ataxia. Diagnosis was based on positive results (VDRL-TPHA) of serological reactions in blood samples and analysis of cerebrospinal fluid showing pleocytosis (mean lymphocyte level, 69%) and elevated protein levels. Epilepsy and chronic headache were the most common clinical manifestations. Brain scan demonstrated low-grade ventricular dilatation associated with nonspecific cerebral atrophy in 8 cases and isolated cerebral atrophy in three. In the remaining 17 cases brain scans were normal.

[Oxidative stress and gene expression]

Oxidative stress elicits cellular toxicity implicating various targets such as DNA, RNA, proteins, lipids.... Similarly to other stress conditions, it triggers cellular adaptation and the induction of defense mechanisms. Adaptation to this stress is ubiquitous but it displays cell specificity. Adaptation to stress requires the regulation of a large number of genes. Those encoding anti-oxidant and repair genes are induced while others are repressed. The activity of several transcription factors is altered by oxidative stress. Many transcription factors are inhibited because of the oxidation of cysteine residues in their DNA binding domains. In the case of NFI, a cysteine in the transactivating domain is oxidized which leads to inactivation. The mechanisms of transcription factor activation are often complex, as in the case of cJun. This factor is activated by a kinase signalling cascade. Paradoxically, it is also inhibited by stress since one of its cysteines is oxidized; however, this oxidation is repaired in the nucleus by the ref1-thioredoxine system. A similar mechanism is observed for NF kappa B. Alteration of the redox status is observed in several physiological pathological and toxic conditions. It is also provoked by other cellular stress, in particular endoplasmic reticulum stress, hypoxia, shear stress, osmotic and heat shocks. The actual role of oxidative stress during other stress conditions remains to be elucidated. This widespread implication of oxidative stress could account for its role in a variety of disease such as neurodegenerative diseases, cancer, atherosclerosis, and diabetes. The efficacy of anti-oxidant therapy depends on the actual contribution of oxidative stress to these diseases.