Functional NADPH oxidase 2 (NOX2) in T cells amplifies salt-sensitive hypertension and associated renal damage

Infiltrating T cells in the kidney amplify salt sensitive (SS) hypertension and renal damage, but the mechanisms are not known. Genetic deletion of T cells (SS^CD247-/-) or of the p67phox subunit of NOX2 (SS^p67phox-/-) attenuates salt-sensitive hypertension in the Dahl SS rat. We hypothesized that reactive oxygen species (ROS) produced by NOX2 in T-cells drive the SS phenotype and renal damage. T cells were reconstituted by adoptively transferring splenocytes (~10 million) from the Dahl SS (SS→CD247), the SS^p67phox-/- (p67phox→CD247) or of only PBS (PBS→CD247) into the SS^CD247-/- rat on postnatal day 5. Animals were instrumented with radiotelemeters and studied at 8 weeks of age. There were no detectable difference in mean arterial pressure (MAP) or albuminuria between groups when the rats were maintained on a low salt (LS, 0.4% NaCl) diet. After 21 days of high salt (HS, 4.0% NaCl), MAP and albuminuria were significantly greater in the SS→CD247 compared to the p67phox→CD247 rats and the PBS→CD247 rats. Interestingly, there was no difference between p67phox→CD247 and PBS→CD247 in albuminuria or MAP after 21 days. The lack of CD3+ cells in the PBS→CD247 but presence of CD3+ cells in rats receiving the T cell transfer demonstrated the effectiveness of the adoptive transfer. No differences in the number of CD3+, CD4+, or CD8+ cells were observed in the kidneys of the SS→CD247 and p67phox→CD247 rats. These results indicate that ROS production by T cells participates in the amplification of salt-sensitive hypertension and renal damage.

Impact of bedding on Dahl salt-sensitive hypertension and renal damage

Salt-sensitive hypertension, increases in blood pressure in response to increased salt intake, is associated with an increased risk of morbidity, mortality, and end-organ damage compared with salt-resistant hypertension. The Dahl salt-sensitive (SS) rat mimics the phenotypic characteristics observed in human hypertension when rats are challenged with a high-salt diet. Our previous work demonstrated that environmental factors, such as dietary protein, alter the severity of salt sensitivity in Dahl SS rats and should be an important consideration in experimental design. The present study investigated how the bedding on which animals were maintained (wood vs. corncob) could impact the SS phenotype in the Dahl SS rat. Animals that were maintained on corncob bedding exhibited a significant attenuation in blood pressure and renal end-organ damage in response to a high-salt diet compared with animals maintained on wood bedding. This attenuation was associated with an improvement in renal function and reduction in immune cell infiltration into the kidneys of Dahl SS rats maintained on corncob bedding. These results indicate that the type of bedding impacts the SS phenotype in the Dahl SS rat and that the bedding used in experiments can be a confounding factor to consider during data interpretation and experimental design.NEW & NOTEWORTHY Results from our present study demonstrate the profound effect of animal bedding on the severity of salt-sensitive hypertension, renal damage, and inflammation in Dahl salt-sensitive rats. This study highlights the important consideration that should be given to environmental factors, namely, the type of bedding in animal facilities, in experimental design and data interpretation.

Abstract 028: Toll-Like Receptor 4 Promotes Renal Immune Cell Infiltration And The Development Of Renal Damage During Dahl Salt-Sensitive Hypertension

Previous work in our laboratory has implicated a significant role for the immune system in potentiating the hypertensive and kidney damage phenotypes which occur in the Dahl Salt-Sensitive (SS) rat. Toll-like receptors (TLRs), usually expressed on macrophages, play a key role in the innate immune system. A number of TLRs have been implicated in cardiovascular disease and chronic kidney disease with particular interest in TLR4, which specifically binds gram-negative lipopolysaccharide or endogenous molecules produced as a result of tissue injury. We previously performed a transcriptomic analysis which demonstrated TLR4 upregulation in renal medullary tissue of Dahl SS rats fed a high salt (4.0% NaCl) diet. The present study tests the hypothesis that TLR4 influences high salt diet-induced hypertension and renal damage in the Dahl SS rat. Using CRISPR/Cas9 technology, a mutation was generated in the TLR4 gene on the Dahl SS background, creating a 1-bp frameshift deletion resulting in a premature stop codon. SS TLR4-/- males and parental Dahl SS males (SS TLR4+/+ ), maintained on a 0.4% NaCl chow, underwent carotid artery telemetry implantation at 7 weeks of age. After recovery and baseline mean arterial pressure (MAP) recordings (day 0: 125.6 ± 0.5 vs 124.2 ± 2 mmHg), animals were switched to a 4.0% NaCl chow for 3 weeks. Overnight urine collections occurred once during the low salt period and weekly throughout the high salt challenge. Kidneys were flushed prior to euthanasia. Although SS TLR4-/- MAP was not different from SS TLR4+/+ during the high salt challenge (day 21: 176.8 ± 14 mmHg, n=2 vs 172.3 ± 18 mmHg, n=4), high salt day 21 urinary albumin excretion was significantly reduced in SS TLR4-/- (272.7 ± 65 mg/day, n=5, p<0.01) compared to SS TLR4+/+ (427.5 ± 67 mg/day, n=7), indicating reduced renal damage in TLR4 absence. Furthermore, flow cytometric analysis of isolated renal immune cells indicated a 33% reduction in CD45+ total leukocytes (5.0 ± 1.2 vs 3.4 ± 0.9 x10 6 cells) and a 31% reduction in CD11bc+ monocytes/macrophages (3.9 ± 0.9 vs 2.6 ± 0.7 x10 6 cells) in SS TLR4-/- (n=5) vs SS TLR4+/+ (n=7) kidneys. Together, these data indicate that TLR4 may drive the immune response during the induction and progression of salt-sensitive hypertension and renal disease.

Identification of Enterococcus species and phenotypically similar Lactococcus and Vagococcus species by reverse checkerboard hybridization to chaperonin 60 gene sequences

Data from four recent studies (S. H. Goh et al., J. Clin. Microbiol. 36:2164-2166, 1998; S. H. Goh et al., J. Clin. Microbiol. 34:818-823, 1996; S. H. Goh et al., J. Clin. Microbiol. 35:3116-3121, 1997; A. Y. C. Kwok et al., Int. J. Syst. Bacteriol. 49:1181-1192, 1999) suggest that an approximately 600-bp region of the chaperonin 60 (Cpn60) gene, amplified by PCR with a single pair of degenerate primers, has utility as a potentially universal target for bacterial identification (ID). This Cpn60 gene ID method correctly identified isolates representative of numerous staphylococcal species and Streptococcus iniae, a human and animal pathogen. We report herein that this method enabled us to distinguish clearly between 17 Enterococcus species (Enterococcus asini, Enterococcus rattus, Enterococcus dispar, Enterococcus gallinarum, Enterococcus hirae, Enterococcus durans, Enterococcus cecorum, Enterococcus faecalis, Enterococcus mundtii, Enterococcus casseliflavus, Enterococcus faecium, Enterococcus malodoratus, Enterococcus raffinosus, Enterococcus avium, Enterococcus pseudoavium, Enterococcus new sp. strain Facklam, and Enterococcus saccharolyticus), and Vagococcus fluvialis, Lactococcus lactis, and Lactococcus garvieae. From 123 blind-tested samples, only two discrepancies were observed between the Facklam and Collins phenotyping method (R. R. Facklam and M. D. Collins, J. Clin. Microbiol. 27:731-734, 1989) and the Cpn60 ID method. In each case, the discrepancies were resolved in favor of the Cpn60 ID method. The species distributions of the 123 blind-tested isolates were Enterococcus new sp. strain Facklam (ATCC 700913), 3; E. asini, 1; E. rattus, 4; E. dispar, 2; E. gallinarum, 20; E. hirae, 9; E. durans, 9; E. faecalis, 12; E. mundtii, 3; E. casseliflavus, 8; E. faecium, 25; E. malodoratus, 3; E. raffinosus, 8; E. avium, 4; E. pseudoavium, 1; an unknown Enterococcus clinical isolate, sp. strain R871; Vagococcus fluvialis, 4; Lactococcus garvieae, 3; Lactococcus lactis, 3; Leuconostoc sp., 1; and Pediococcus sp., 1. The Cpn60 gene ID method, coupled with reverse checkerboard hybridization, is an effective method for the identification of Enterococcus and related organisms.

Long-term treatment with diazoxide in childhood hyperinsulinism

This paper reviews the outcome in 12 children with hyperinsulinaemic hypoglycaemia who first developed symptoms between the ages of 2 and 8 months and who were treated with diazoxide (5-20 mg/kg/day) for 2-13 years. Two cases required subtotal pancreatectomy at the ages of 5 and 10 years because of recurrent hypoglycaemia and one girl with severe retardation died at the age of 6 years while still on diazoxide therapy. Two patients aged 3.5 and 9 years are still on treatment and in 7 cases diazoxide was discontinued between the ages of 2.5 and 14 years, indicating that spontaneous remission can be expected in a high proportion of children with post-neonatal hyperinsulinaemic hypoglycaemia. Of the 9 children who started diazoxide within 3 months of the onset of symptoms, 5 are of normal intelligence and 4 are moderately retarded (IQs 63-71). In 3 children diazoxide was started 8 months to 3 years after the onset of symptoms; two are retarded (IQs 60-70) and the third was severely retarded and died aged 6 years.

Raynaud's disease

We report five children who presented with Raynaud's disease in whom we could find no clinical, haematological, or immunological evidence of a collagen disorder. Oral phenoxybenzamine proved useful for maintenance treatment in most, with infusions of prostacyclin, nitroprusside, and ketanserin during acute attacks.

Long term management of congenital cataracts

Presentation and outcome, particularly in terms of development, nursery, and school placement of 55 children with treated congenital cataracts was studied. Results indicate that although most children have satisfactory vision many of their parents would have welcomed more support at the time of the diagnosis, an opportunity to talk to parents of similarly affected children, and further advice on their child's early development and educational placement. It is suggested that improved communications between clinicians, therapists, and teachers, and parents' support groups would be helpful to these families.

Investigation of suspected growth hormone deficiency. On behalf of the Health Services Human Growth Hormone Committee

This paper describes views of the Health Services Human Growth Hormone Committee on how a child suspected of growth hormone deficiency should be investigated in a district general hospital or in a regional growth centre.

Growth hormone treatment in children with craniopharyngioma: final growth status

Twenty-seven out of thirty craniopharyngioma patients treated with human growth hormone (hGH) for 2 years or more (average 4.5 years) reached final adult heights above the population third centile, though none was above the fiftieth centile. However, only twelve of twenty-eight patients had final heights above the lower limits to be expected from their parents' heights. All patient eventually had long legs relative to sitting height (final mean subischial leg length SDS = + 0.2, final mean sitting height SDS = -3.0). Twenty-nine patients were TSH-deficient, twenty-two were ACTH-deficient, thirteen were deficient in ADH and all had total (85%) or partial (15%) gonadotrophin deficiency. Following the administration of testosterone or hCG the boys had, on average, only half the normal adolescent growth spurt. This may have been due to the lateness of starting androgens in these patients and we recommend, when considering height, that testosterone or hCG should be started when a bone age of 13.0 "years' is reached or when a lower bone age has remained unchanged for a year. The girls showed adolescent height spurt; the average increase after oestrogen treatment commended was 1.7 cm.