Association of post-transplantation anellovirus viral load with kidney transplant rejection in children.

BACKGROUND: Post-transplantation immunosuppressive therapy reduces the risk of graft rejection but raises the risk of infection and malignancy. A biomarker of the level of immunosuppression can be helpful in monitoring immunosuppressive therapy. Inverse correlation between Torque teno virus (TTV) from the Anelloviridae (AV) family load and immune competence was described in previous studies. The aim of this study was to analyze the association between AV family viruses' kinetics and the risk for graft rejection in the first year after kidney transplantation in children. METHODS: The titers of three genera (TTV, TTMDV, and TTMV) from the AV family were monitored by real-time PCR in consecutive samples from children before and after kidney transplantation. RESULTS: Twenty-one children who underwent kidney transplantation were enrolled. Five out of 21 patients experienced acute graft rejection within a year from transplantation. We found that in patients who experienced graft rejection, the median titers of TTV and total AV titers at 5-6 months post-transplantation were lower than in those who did not. Using a threshold determined by ROC analysis, significant differences in TTV and total AV load were found between patients who had or did not have graft rejection (p = 0.002 and 0.004, respectively). No association was found between the dominance of any AV genus titer and the likelihood of rejection. CONCLUSION: This pilot study suggests that children after kidney transplantation with low TTV and total AV titers 5-6 months post-transplantation are at increased risk for graft rejection within a year after transplantation. A higher resolution version of the Graphical abstract is available as Supplementary information.

Dent's disease manifesting as focal glomerulosclerosis: Is it the tip of the iceberg?

Dent's disease is an X-linked proximal tubulopathy. It often manifests in childhood with symptoms of Fanconi syndrome and low-molecular-weight proteinuria. We describe four boys from three unrelated families whose only presenting symptoms of Dent's disease were nephrotic-range proteinuria and histological findings of focal segmental and/or global glomerulosclerosis. In all families, a causal mutation in the CLCN5 gene, encoding a voltage-gated chloride transporter and chloride-proton exchanger, was identified. All three mutations are pathogenic: two are novel (p.Asp727fs and p.Trp122X), and one is a recurrent mutation, p.R648X. Given the atypical phenotype of these patients with Dent's disease, it is possible that this clinical entity is markedly underdiagnosed and that our report represents only the tip of the iceberg. The diagnosis of Dent's disease should be considered in all patients with nephrotic-range proteinuria without hypoalbuminemia or edema. Establishing the diagnosis of Dent's disease will prevent the administration of unnecessary immunosuppressive medications with their undesirable side effects.

Mutations in DDR2 gene cause SMED with short limbs and abnormal calcifications.

The spondylo-meta-epiphyseal dysplasia [SMED] short limb-hand type [SMED-SL] is a rare autosomal-recessive disease, first reported by Borochowitz et al. in 1993.(1) Since then, 14 affected patients have been reported.(2-5) We diagnosed 6 patients from 5 different consanguineous Arab Muslim families from the Jerusalem area with SMED-SL. Additionally, we studied two patients from Algerian and Pakistani ancestry and the parents of the first Jewish patients reported.(1) Using a homozygosity mapping strategy, we located a candidate region on chromosome 1q23 spanning 2.4 Mb. The position of the Discoidin Domain Receptor 2 (DDR2) gene within the candidate region and the similarity of the ddr2 knockout mouse to the SMED patients' phenotype prompted us to study this gene(6). We identified three missense mutations c.2254 C > T [R752C], c. 2177 T > G [I726R], c.2138C > T [T713I] and one splice site mutation [IVS17+1g > a] in the conserved sequence encoding the tyrosine kinase domain of the DDR2 gene. The results of this study will permit an accurate early prenatal diagnosis and carrier screening for families at risk.

Utilizing a GnRH-based chimeric protein for the detection of adenocarcinoma.

Since early diagnosis of many types of cancer greatly improves the chances for successful treatment, high-quality methods for cancer detection are necessary. Our laboratory develops chimeric proteins for targeted therapy, such as gonadotropin releasing hormone (GnRH)-based chimeric proteins for the targeted therapy of adenocarcinomas in humans. For chimeric proteins to cause specific cell death, they must first recognize specific receptors/binding sites expressed on the surface of target cells. Thus, we examined whether we could exploit these binding sites not only as targets for the killing of specific cells but also as a diagnostic marker for identifying adenocarcinomas, using the same chimeric proteins. In this report, we show that one such GnRH-based chimeric protein, GnRH-Caspase3, can indeed serve as a diagnostic tool. GnRH-Caspase3 was able to specifically bind adenocarcinoma cells, as measured by FACS analysis and demonstrated with the aid of confocal microscopy and specific antibodies. Moreover, we found a correlation between cell sensitivity to treatment and the binding level of the chimeric protein to the cells. Hence, we suggest that in addition to their therapeutic potential, GnRH-based chimeric proteins can be used as a diagnostic tool for the detection of adenocarcinomas.

Utilizing chimeric proteins for exploring the cellular fate of endogenous proteins.

We recently designed and constructed chimeric proteins for the elimination of specific cell populations. These chimeric proteins are composed of a targeting component fused to an apoptotic protein as the killing moiety. However, chimeric proteins can serve not only to eliminate cell populations, but also as "biological tools" for studying the fate of endogenous proteins. We show here that upon entering their target cell, a variety of chimeric proteins composed of an endogenous protein as their killing moiety reach the subcellular location of their endogenous counterpart. In contrast, bacterial-based killing domains head for the subcellular site of their substrate. Moreover, the chimeric protein acts similarly to the endogenous protein, while causing the cell to die. Therefore, chimeric proteins may serve as a unique tool for investigating cellular proteins and their intracellular localization, without the need to overexpress them.