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El Kholy M.,Ain Shams University | Mella P.,Institute of Molecular Medicine Angelo Nocivelli | Rashad M.,Ain Shams University | Buzi F.,University of Brescia | And 3 more authors.
Hormone Research in Paediatrics | Year: 2011

Background/Aims: It was hypothesized that some children with idiopathic short stature (ISS) may have partial insensitivity to growth hormone (GH). In this study analysis of the GH/IGF-I axis as well as GH receptor (GHR) gene was done in children with ISS to determine the possible underlying factor(s) to their short stature. Methods: Forty-eight patients with a diagnosis of ISS were studied; 33 boys and 15 girls aged 13.6 ± 3.7 years. Molecular analysis of the GHR was performed and GH sensitivity was tested by the IGF-I generation test. Results: Basal IGF-I levels were <-2 SD in 22.9%, and 53.5% showed an IGF-I response below 40% (0-38%) to GH stimulation. GH-binding protein (GHBP) levels were below the normative mean in almost all patients. Mutations in the region of the GHR gene that codes for the extracellular domain of the receptor were found in 15.5%; one newly described mutation was recorded. Conclusion: With the possible exception of the novel G62V mutation, functional studies of the other 2 heterozygous mutations found in 6 of our patients are needed in order to prove their impact on short stature. © 2011 S. Karger AG, Basel.

Kallikourdis M.,Humanitas Clinical and Research Center | Kallikourdis M.,University of Milan | Trovato A.E.,Humanitas Clinical and Research Center | Anselmi F.,Humanitas Clinical and Research Center | And 7 more authors.
Blood | Year: 2013

WHIM (warts, hypogammaglobulinemia, infections, myelokathexis) syndrome is a rare disease characterized by diverse symptoms indicative of aberrantly functioning immunity. It is caused by mutations in the chemokine receptor CXCR4, which impair its intracellular trafficking, leading to increased responsiveness to chemokine ligand and retention of neutrophils in bone marrow. Yet WHIM symptoms related to adaptive immunity, such as delayed IgG switching and impaired memory B-cell function, remain largely unexplained. We hypothesized that the WHIM-associated mutations in CXCR4 may affect the formation of immunologic synapses between T cells and antigen-presenting cells (APCs). We show that, in the presence of competing external chemokine signals, the stability of T-APC conjugates from patients with WHIM-mutant CXCR4 is disrupted as a result of impaired recruitment of the mutant receptor to the immunologic synapse. Using retrogenic mice that develop WHIM-mutant T cells, we show that WHIM-mutant CXCR4 inhibits the formation of long-lasting T-APC interactions in ex vivo lymph node slice time-lapse microscopy. These findings demonstrate that chemokine receptors can affect T-APC synapse stability and allow us to propose a novel mechanism that contributes to the adaptive immune response defects in WHIM patients. © 2013 by The American Society of Hematology.

Tassone L.,Institute of Molecular Medicine Angelo Nocivelli | Moratto D.,Institute of Molecular Medicine Angelo Nocivelli | Vermi W.,University of Brescia | De Francesco M.,University of Brescia | And 6 more authors.
Blood | Year: 2010

Warts, hypogammaglobulinemia, infections, myelokathexis (WHIM) syndrome is a genetic disease that is caused by heterozygous mutations of the CXCR4 gene. These mutations confer an increased leukocyte response to the CXCR4-ligand CXCL12, resulting in abnormal homeostasis of many leukocyte types, including neutrophils and lymphocytes. Analysis of the myeloid and plasmacytoid dendritic cell blood counts in WHIM patients revealed a striking defect in the number of plasmacytoid dendritic cells as well as a partial reduction of the number of myeloid dendritic cells, compared with healthy subjects. Moreover, the production of interferon-α by mononuclear cells in response to herpes simplex infection, or after stimulation with the Toll-like receptor 9 ligand CpG, was undetectable in WHIM patients. Because plasmacytoid dendritic cells play a key role in the defense against viruses and their generation and motility are in part dependent on CXCR4, we hypothesized that the susceptibility of WHIM patients to warts is related to the abnormal homeostasis of plasmacytoid dendritic cells. © 2010 by The American Society of Hematology.

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