Generation of functional human T cell development in NOD/SCID/IL2rγnull humanized mice without using fetal tissue: Application as a model of HIV infection and persistence.

Humanization of mice with functional T cells currently relies on co-implantation of hematopoietic stem cells from fetal liver and autologous fetal thymic tissue (so-called BLT mouse model). Here, we show that NOD/SCID/IL2rγnull mice humanized with cord blood- derived CD34+ cells and implanted with allogeneic pediatric thymic tissues excised during cardiac surgeries (CCST) represent an alternative to BLT mice. CCST mice displayed a strong immune reconstitution, with functional T cells originating from CD34+ progenitor cells. They were equally susceptible to mucosal or intraperitoneal HIV infection and had significantly higher HIV-specific T cell responses. Antiretroviral therapy (ART) robustly suppressed viremia and reduced the frequencies of cells carrying integrated HIV DNA. As in BLT mice, we observed a complete viral rebound following ART interruption, suggesting the presence of HIV reservoirs. In conclusion, CCST mice represent a practical alternative to BLT mice, broadening the use of humanized mice for research.

Malignant Rhabdoid Tumor of Soft Tissue.

Introduction Malignant rhabdoid tumor (MRT) is defined as a high-grade sarcoma derived from an uncertain cell of origin. Its diagnosis is associated with poor prognosis and patient's life expectancy is greatly reduced. Material and method Here, we describe a unique case of 9-month-old boy who presented with a large MRT arising from the soft tissue of the neck. Following intensive multimodal treatment, the patient benefited from a 25 years' remission until the discovery of multiple liver metastases. Conclusion MRT of soft tissue needs to be distinguished from other soft tissue neoplasms, as MRT is highly aggressive and is usually associated with a poor outcome. In addition, this is the longest remission time reported in a patient with soft tissue MRT and this might be related to the use of early intensive multimodal treatments.

Pediatric Non-Alcoholic Fatty Liver Disease.

The rapidly increasing prevalence of childhood obesity and its associated co-morbidities such as hypertriglyceridemia, hyper-insulinemia, hypertension, early atherosclerosis, metabolic syndrome, and non-alcoholic fatty liver disease are major public health concerns in many countries. Therefore the trends in child and adolescent obesity should be closely monitored over time, as in the near future, we may anticipate a major increase of young adults with the stigmata of the metabolic syndrome, and of the related non-alcoholic fatty liver disease (NAFLD), that may lead to non-alcoholic steatohepatitis.

Involvement of the fractalkine pathway in the pathogenesis of childhood hemolytic uremic syndrome.

Thrombotic microangiopathy and acute renal failure are cardinal features of postdiarrheal hemolytic uremic syndrome (HUS). These conditions are related to endothelial and epithelial cell damage induced by Shiga toxin (Stx) through the interaction with its globotriaosyl ceramide receptor. However, inflammatory processes contribute to the pathogenesis of HUS by sensitizing cells to Stx fractalkine (FKN), a CX(3)C transmembrane chemokine expressed on epithelial and endothelial cells upon activation, is involved in the selective migration and adhesion of specific leukocyte subsets to tissues. Here, we demonstrated a selective depletion of circulating mononuclear leukocytes expressing the receptor for FKN (CX(3)CR1) in patients with HUS. We found a unique phenotype in children with HUS distinct from that seen in healthy, uremic, or infected controls, in which monocytes lost CX(3)CR1, down-modulated CD62L, and increased CD16. In addition, the CD56(dim) natural killer (NK) subpopulation was decreased, leading to an altered peripheral CD56(dim)/CD56(bright) ratio from 10.0 to 4.5. It is noteworthy that a negative correlation existed between the percentage of circulating CX(3)CR1(+) leukocytes and the severity of renal failure. Finally, CX(3)CR1(+) leukocytes were observed in renal biopsies from patients with HUS. We suggest that the interaction of CX(3)CR1(+) cells with FKN present on activated endothelial cells may contribute to renal injury in HUS.