Digestive histopathological presentation of IPEX syndrome.

Immunodysregulation, polyendocrinopathy, enteropathy, and X-linked inheritance (IPEX) syndrome is a well recognized and particularly severe form of autoimmune enteropathy. It has an X-linked recessive transmission, and is caused by mutations in the FOXP3 gene. We studied the intestinal morphological changes characterizing IPEX syndrome in a series of 12 children with a molecularly confirmed diagnosis. Histological examination of duodenal, gastric and colonic biopsies were retrospectively reviewed and compared by two independent experienced pathologists. In parallel, the presence of circulating anti-enterocyte antibodies was analysed using an indirect immunofluorescence technique and a quantitative radioligand assay against the 75-kDa autoantigen. The morphology of the inflammatory gut lesions could be categorized into three different entities, namely graft-vs-host disease-like changes (9/12 patients), a coeliac disease-like pattern (2/12) and an enteropathy with a complete depletion of goblet cells (1/12). Our results do not suggest any phenotype-genotype correlation. Circulating antibodies were detected in all 12 patients, with an anti-brush border pattern (11/12) and anti-goblet cell antibodies (1/12), as well as by a radioligand assay. The histological presentation of autoimmune enteropathy is rather variable. However, a graft-vs-host disease-like pattern associated with positive anti-enterocyte antibodies is the most frequent intestinal presentation of IPEX syndrome, and constitutes a very valuable tool for pathologists to suspect this diagnosis.

[Collagen alpha5 and alpha2 (IV) chain coexpression: The procedure of choice to diagnose Alport syndrome from skin biopsies]. / Coexpression des chaînes alpha5 et alpha2 (IV) : une technique de choix pour le diagnostic de syndrome d'Alport à partir d'une biopsie cutanée.

We describe a simple procedure to use skin biopsies for the diagnosis of Alport syndrome. The technique is based on the co-detection of alpha5 and alpha2 chains of collagen IV along the basal lamina of epidermis through an immunfluorescence technique. Eighty-five per cent of the cases of Alport syndrome are due to a mutation in the gene COL4A5, located on chromosome X, encoding the alpha5 chain of collagen IV. In this situation, the tissue expression of alpha5 chain is abnormal; in males, the absence of expression of alpha5 chain is pathognomonic for Alport syndrome; in females, the expression of alpha5 chain may be discontinuous because of X inactivation. The alpha2 chain is used as a positive control. We have studied skin biopsies from 55 patients (35 females, 20 males) with a suspicion of Alport syndrome, along with five controls. Immunofluorescence was performed on frozen tissue samples; for lecture, epifluorescence and confocal microscopy were compared. In controls, both chains were co-detected. In nine males out of 20, the expression of alpha5 was undetectable; it was preserved in the remaining cases. In female patients, the expression was discontinuous in 16 cases and undetectable in one. There was no difference in sensitivity between the two microscopic techniques. The co-detection of alpha5 and alpha2 chains of collagen IV in frozen skin biopsies is therefore proposed as a simple technique to diagnose Alport syndrome, but requires a good knowledge of the conditions of interpretation.

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 ( approximately 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(+) CD25(high) FoxP3(high) 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.

Gonad development in Drash and Frasier syndromes depends on WT1 mutations.

The study of the gonads of 8 cases of Drash syndrome (6 ambiguous males, 2 females) and of 2 Frasier syndrome shows that WT1 mutations gives a dysgenetic testis which is the cause of the genital ambiguity observed at birth. By contrast the same mutations have no effect on ovary development giving normal females. However intron mutations in KTS with isoforms imbalance of WT1 proteins cause streak gonads with a female phenotype in XY patients. In consequence WT1 mutations are the cause of a spectrum of male genital malformations associated with glomerulonephritis and tumors. The absence of WT1 protein detection in sertoli cells shown by immunohistochemistry for 3 cases suggests an imprinting effect of the normal WT1 allele promotor rather than a low level of protein production. A caryotype is mandatory for a correct diagnosis.

A t(17;22)(q21;q12) with partial ETV4 deletion in a soft tissue Ewing sarcoma.

Cytogenetic analysis of a lumbar soft tissue Ewing sarcoma (ES) in a 7-month-old female child showed a t(17;22)(q21;q12), a rare translocation leading to an EWSR1-ETV4 chimeric transcript. These findings were confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) techniques. The breakpoints were characterized by direct sequencing of the chimeric fusion gene. Tumor genotyping using the Affymetrix Genome-Wide Human single nucleotide polymorphism (SNP) array 6.0 Genechip identified deletions of both chromosomal regions involved in the translocation, resulting in partial deletion of ETV4, but an uninvolved EWSR1 gene. The creation of a fusion between EWSR1 and an ETS family gene consecutive to a chromosomal translocation is characteristic of the Ewing family of tumors (EFT). This is the first report of a deletion involving the two breakpoints in an EWS-ETS translocation. To date, only two cases of t(17;22)(q21;q12) in Ewing sarcoma have been reported, with no associated deletion. Interestingly, both cases had also occurred in soft tissue tumors, which are less common than their bone-involving counterparts.