Rare SH2B3 coding variants in lupus patients impair B cell tolerance and predispose to autoimmunity

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with a clear genetic component. While most SLE patients carry rare gene variants in lupus risk genes, little is known about their contribution to disease pathogenesis. Amongst them, SH2B3-a negative regulator of cytokine and growth factor receptor signaling-harbors rare coding variants in over 5% of SLE patients. Here, we show that unlike the variant found exclusively in healthy controls, SH2B3 rare variants found in lupus patients are predominantly hypomorphic alleles, failing to suppress IFNGR signaling via JAK2-STAT1. The generation of two mouse lines carrying patients' variants revealed that SH2B3 is important in limiting the number of immature and transitional B cells. Furthermore, hypomorphic SH2B3 was shown to impair the negative selection of immature/transitional self-reactive B cells and accelerate autoimmunity in sensitized mice, at least in part due to increased IL-4R signaling and BAFF-R expression. This work identifies a previously unappreciated role for SH2B3 in human B cell tolerance and lupus risk.

Massively parallel sequencing and targeted exomes in familial kidney disease can diagnose underlying genetic disorders

Inherited kidney disease encompasses a broad range of disorders, with both multiple genes contributing to specific phenotypes and single gene defects having multiple clinical presentations. Advances in sequencing capacity may allow a genetic diagnosis for familial renal disease, by testing the increasing number of known causative genes. However, there has been limited translation of research findings of causative genes into clinical settings. Here, we report the results of a national accredited diagnostic genetic service for familial renal disease. An expert multidisciplinary team developed a targeted exomic sequencing approach with ten curated multigene panels (207 genes) and variant assessment individualized to the patient's phenotype. A genetic diagnosis (pathogenic genetic variant[s]) was identified in 58 of 135 families referred in two years. The genetic diagnosis rate was similar between families with a pediatric versus adult proband (46% vs 40%), although significant differences were found in certain panels such as atypical hemolytic uremic syndrome (88% vs 17%). High diagnostic rates were found for Alport syndrome (22 of 27) and tubular disorders (8 of 10), whereas the monogenic diagnostic rate for congenital anomalies of the kidney and urinary tract was one of 13. Quality reporting was aided by a strong clinical renal and genetic multidisciplinary committee review. Importantly, for a diagnostic service, few variants of uncertain significance were found with this targeted, phenotype-based approach. Thus, use of targeted massively parallel sequencing approaches in inherited kidney disease has a significant capacity to diagnose the underlying genetic disorder across most renal phenotypes.

Fungi isolated from tobacco leaves and brown-spot lesions before and after flue-curing

Discs of tissue excised from ripe nonflue-cured and flue-cured tobacco leaves, harvested on six dates and cultured on three selective media, yielded 21 and 24 genera of fungi, respectively. Of 5,094 fungi isolated from 3,240 pieces of nonfluecured leaf tissue, 89.5% comprised five genera, Alternaria, Cladosporium, Epicoccum, Trichoderma, and Nigrospora. Of 2,494 fungi isolated from 3,240 pieces of flue-cured leaf tissue, 70.9% were Alternaria, Cladosporium Epicoccum, Aspergillus, and Nigrospora. Flue-cured and nonflue-cured brown-spot lesions harvested at two locations yielded 12 and 14 genera of fungi, respectively. Alternaria, Penicillium, Phoma, and Stemphyllium comprised 91.5% of the 2,245 fungi isolated from noncured and 87.1% of the 1,118 fungi isolated from the cured lesions. The number and kinds of fungi obtained from diseased and healthy tissue were reduced but not eliminated by flue-curing.

Vesicoureteral reflux

Vesicoureteral reflux (VUR), the retrograde flow of urine from the bladder toward the kidney, is common in young children. About 30% of children with urinary tract infections will be diagnosed with VUR after a voiding cystourethrogram. For most, VUR will resolve spontaneously; 20% to 30% will have further infections, but few will experience long-term renal sequelae. Developmentally, VUR arises from disruption of complex signaling pathways and cellular differentiation. These mechanisms are probably genetically programmed but may be influenced by environmental exposures. Phenotypic expression of VUR is variable, ranging from asymptomatic forms to severe renal parenchymal disease and end-stage disease. VUR is often familial but is genetically heterogeneous with variability in mode of inheritance and in which gene, or the number of genes, that are involved. Numerous genetic studies that explore associations with VUR are available. The relative utility of these for understanding the genetics of VUR is often limited because of small sample size, poor methodology, and a diverse spectrum of patients. Much, if not all, of the renal parenchymal damage associated with end-stage disease is likely to be congenital, which limits the opportunity for intervention to familial cases where risk prediction may be available. Management of children with VUR remains controversial because there is no strong supportive evidence that prophylactic antibiotics or surgical intervention improve outcomes. Furthermore, well-designed genetic epidemiological studies focusing on the severe end of the VUR phenotype may help define the causal pathway and identify modifiable or disease predictive factors.

Nephrotoxicity with cyclooxygenase 2 inhibitor use in children

The nephrotoxic potential of anti-inflammatory drugs alone and in compound preparations has been known for over fifty years. Nephrotoxicity associated with selective cyclooxygenase 2 (COX-2) inhibitor use is reported in adult patients but not in children. We present here the first report of reversible acute renal failure associated with the COX-2 inhibitor rofecoxib (Vioxx) in three children. Patient 1, an 18 month old girl with neonatal Bartter syndrome, developed acute renal failure with a peak creatinine of 1.9 mg/dl (164 micromol/l) and severe hyperkalemic metabolic acidosis. Patient 2, a 14 year old boy with a history of rheumatic fever, developed acute renal failure with a peak creatinine of 2.7 mg/dl (240 micromol/l). While patient 3, a healthy 14 year old girl, developed acute renal failure and tubulointerstitial nephritis confirmed on renal biopsy with a peak creatinine of 3.3 mg/dl (287 micromol/L). All children had been taking non-selective non-steroidal anti-inflammatory drugs (NSAID's) immediately prior to rofecoxib use. Renal function returned to normal within one week in all three patients and has remained normal at follow-up. This paper highlights the nephrotoxic risk of COX-2 inhibitor use in the pediatric population.

Genesis of neurons in the retinal ganglion cell layer of the monkey

We have analyzed the genesis of various neuronal classes and subclasses in the ganglion cell layer of the primate retina. Neurons were classified according to their size and the time of their origin was determined by pulse labeling with 3H-thymidine administered to female monkeys 38 to 70 days pregnant. All offspring were sacrificed postnatally, and their retinas processed for autoradiography. The somata of cells in the retinal ganglion cell layer generated on embryonic day (E) 38 ranged from 9 to 14 microns in diameter. Between E40 and E56, the minimum soma diameter remained around 8-9 microns, while the maximum gradually increased to 22 microns. As a consequence, the means of the distributions of labeled cells also increased with age, from 11.8 microns diameter for cells generated on E38 to 14.6 microns diameter at E56. Over this period the percentage of labeled cells in the 10.5-16.5 microns and greater than 16.5 microns diameter range gradually increased. The proportion of the labeled cells in the less than 10.5 microns diameter range decreased from E38 to E45, but subsequently increased rapidly. At the end of neurogenesis in the retinal ganglion cell layer, around E70, most labeled cells were considerably smaller (7-9 microns) than those generated earlier. Our results indicate that within the ganglion cell layer of the macaque, neurons of small caliber are generated first, followed successively by medium sized cells. Large, putative P alpha cells are generated late. The production between E56 and E70 of cells with the smallest somata suggests that the last-generated neurons in the ganglion cell layer are predominantly displaced amacrine cells. Within the same sector of retina, different classes of neurons in the ganglion cell layer of the rhesus monkey appear to have a sequential schedule of production.

Antibody responses to experimental Brugia malayi infections in patas and rhesus monkeys

Humoral antibody responses in experimental infections with Brugia malayi (subperiodic strain) were compared in two primate species. Erythrocebus patas and Macaca mulatta. Antibody responses were related to the infection protocol and the duration and magnitude of microfilaremia. Patas monkeys were uniformly susceptible to infection and characteristically exhibited prolonged microfilaremia; infections in Rhesus monkeys produced low and usually microfilaremia. Antibody, measured by enzyme linked immunosorbent assay with extracts of adult Brugia and microfilariae as antigens, declined at patency in Patas monkeys and there was an inverse relationship between serum antibody concentration and the number of circulating microfilariae. Rhesus monkeys generally had high, sustained antibody levels relative to Patas monkeys, but antibody levels were comparable in the two species when the numbers of circulating microfilariae were similar. By fluorescent antibody technique, antibodies reactive with somatic antigens of microfilariae were detected in all infected monkeys; antibodies reactive with the cuticle of infective larvae were also present in both primates and were consistently detected in monkeys receiving multiple infections. Antibodies (IgG, IgM) reactive with the sheath of microfilariae were detected only in certain Rhesus monkeys which were essentially amicrofilaremic and sera with antibodies specific for microfilarial sheath promoted in vitro microfilarial agglutination and leukocyte adherence.

The identification of strains of tobacco mosaic virus from tomato crops in Southern Ontario

Two hundred and nine isolates of tobacco mosaic virus (TMV) were collected from the spring and fall greenhouse crops, and the field crop of Southern Ontario. Strains of the virus were identified on a series of differentials which included Pelham's four tomato lines heterozygous for the genes Tm-1, Tm-2, Tm-1 + Tm-2, and Tm-22 respectively. There were 164 isolates of TMV strain 0, 15 of strain 1, and 30 which were intermediate in character. Strains 2 and 1.2 were not found. The reactions of a number of lines of Tm-1 differentials of independent origin were compared and found to vary with some virus isolates. The recently introduced TMV-tolerant cultivar Vendor did not have any marked influence on the TMV strain situation in the commercial greenhouse crops either to reduce strain 0 types or to bulk-up strain 1 types which might find this cultivar a congenial host.