Abstract MP51: Isolevuglandins In Antigen-presenting Cells, A Biomarker For Salt Sensitivity Of Blood Pressure In Humans?

Background: High Na+ stimulates antigen-presenting cells (APCs) in an ENaC dependent manner, with formation of isolevuglandin (isoLG) adducts (neoantigen peptides) that promote T cell activation and salt sensitive (SS) hypertension in rodents. Methods: We studied this pathway in 9 subjects with essential hypertension who discontinued anti-hypertensive therapy for 2 weeks. Their SS was assessed by 24-hrs of salt loading (460 mmoL) and salt depletion (10 mmoL/24 hr, plus furosemide 40 mg x 3). Muscle and skin Na + were measured at baseline (BA) by 23 Na magnetic resonance imaging (NaMRI). The % of APCs containing isoLG adducts (flow cytometry), urine and serum electrolytes and epoxyeicosatrienoic acids (EETs 8-9, 11-12 and 14-15) were measured at BA, after salt-loading (HI) and after salt-depletion (LO). Results: Age was 54 years (48-56), with 23% female, BMI 30 kg/m 2 (28-40) and screening SBP 136 mmHg (120-144), and DBP 85 mmHg (75-99). BA 24-hr urine Na + excretion was 178 (143-212) mmoL, Hi 392 (229-421) and LO 27 (25-29). SBP response to salt-depletion varied from -13.8 to +5.6 mmHg. Muscle Na+ correlated with duration of hypertension (r=0.73, p<0.03) and with SBP, DBP and mean arterial pressure (MAP) during BA, HI and LO (r=0.66 to 0.87). Mean %isoLGs in APCs were not different among the three stages of the protocol but ΔisoLGs due to HI or LO had positive correlations with ΔSBP, ΔDBP and ΔMAP produced by the same interventions (r=0.46 to 0.70). A 10% change in dendritic cell isoLGs predicted a 1.45 mmHg change of SBP in the same direction. Urine (not plasma) EETs (sum of three isoforms) showed negative correlations with isoLGs on the three phases of the protocol (r=0.57 to 0.69), and ΔEETs by HI and LO correlated negatively with ΔisoLGs produced by the same interventions (r=0.58 to 0.77). Conclusions: Muscle Na+ increases with duration of hypertension and correlates with severity of BP elevation. Changes in APC isoLGs due to Na+ loading or depletion seem to be a biomarker of SS of BP in humans. Relations between urine EETs and ΔEETs with APC isoLGs and ΔisoLGs suggest that EETs might be inhibitors of APC ENaC as they are of renal ENaC. Relationships between isoLGs and urine but not plasma EETs suggest that activation of APCs by high salt may occur in the hyperosmolar renal medulla.

Abstract 11: Single Cell Eccite-seq Analysis Reveal An Important Role Of Monocyte-specific Nlrp3 Inflammasome For Salt-sensitivity Of Hypertension In Humans

Salt sensitivity of blood pressure is an independent predictor of death due to cardiovascular events. Diagnosis of salt-sensitivity is not feasible in the clinic, making it difficult to investigate therapeutic strategies. We hypothesized that NLRP3-inflammasome and IL-1β production in monocytes plays a role in salt-sensitive hypertension. We phenotyped salt-sensitivity of blood pressure using an acute inpatient Weinberger protocol of an isocaloric high salt diet and rapid intravenous salt-loading, followed by low salt diet and furosemide-induced salt-depletion. Ambulatory blood pressure was continuously monitored and averaged for the days of salt-loading and salt-depletion. Blood samples were obtained at baseline, salt-loading, and after salt-depletion. Median age was 54 years (44-55), 3 of the 5 subjects were female, screening systolic blood pressure was 140 mmHg (134-148), diastolic blood pressure was 88 mmHg (84-99), and BMI was 35 kg/m 2 (30-39). Using cell hashing and ECCITE-seq analysis, we profiled transcriptomes in multiple immune cell types using antibody-derived tags (ADTs). UMAP clustering of different cell types were identified by ADTs including monocyte markers CD14 and CD16. Interestingly, UMAP visualization of CD14+ and CD16+ clusters indicated a greater decrease in CD14+ clusters after salt-depletion in the salt-resistant subjects than the salt-sensitive; however the salt-sensitive subjects had a greater decrease in CD16+ clusters than the salt-resistant group after both salt-loading and salt-depletion. These data were confirmed using flow cytometry. Unlike in salt-resistant participants, we found that within monocyte clusters, salt-sensitivity was associated with down regulation of the inflammasome components NLRP3 (0.386 ± 1.18 vs. 0.197 ± 0.778) and IL-1β (0.858 ± 2.32 vs. 0.159 ± 0.925) following salt-depletion. Using flow cytometry, we found Δ% isoLG+ CD14+/CD16+ monocytes correlated with salt-sensitivity of blood pressure (r=0.88, 95% CI, p=0.05). These results suggest that the inflammasome and monocyte activation are dynamically regulated by dietary salt in vivo and can serve as a potential diagnostic biomarker for salt-sensitivity of blood pressure.

ASSESSMENT OF THE FREQUENCY OF DIFFERENT PATTERNS OF CLINICAL PRESENTATION OF CHILDREN PRESENTING WITH CONGENITAL ADRENAL HYPERPLASIA

Objective: To assess the frequency of different patterns of presentation of children presenting with congenital adrenal hyperplasia. Methodology:It was a cross sectional study conducted at the department of Pediatric, Fatima Memorial Hospital, Lahore, from19-12-2017 to 19-06-2018.92 infants who met the selectin criteria were recruited for the study. Then blood sample was obtained and if serum sodium <135mEq/L, then salt depletion was labeled. Then, infants underwent genital examination for assessment of genital virilization. All data is entered is specially designed Performa and analyzed in SPSS. Results: The mean age of patients was 6.52±3.56months. There were 49 (53.26%) male while 43 (46.74%) female infants. The mean weight of patients was 5.59±1.44kg. There were 21 (22.83%) cases of consanguineous marriage while 71 (77.17%) were other than cousin marriage. There were 63 (68.48%) had salt depletion while in 29 (31.52%) did not had salt depletion. There were 39 (42.39%) had genital virilization while in 53 (57.61%) did not had genital virilization. Conclusion: Thus the frequency of patterns (salt depletion and genital virilization) of Congenital adrenal hyperplasia are high in local population.

Abstract P139: The Relationship Between Tissue Sodium Storage, Immune Cell Activation And Salt-sensitive Hypertension

Introduction: Salt Sensitivity (SS) of blood pressure (BP) is an independent predictor of death due to cardiovascular disease, but its pathogenesis is poorly understood. Sodium (Na + ) is stored in the skin and muscle interstitium. This hyperosmolar Na + activates monocytes in vitro via oxidative stress with generation of isolevuglandin (isoLG) protein adducts that are immunogenic and activate the adaptive immune system. Methods: Five subjects with essential hypertension discontinued all anti-hypertensive therapy for two weeks before the study. SS was assessed by an inpatient protocol of salt loading (460 mmoL/24h) and salt depletion (10 mmoL/24h, plus furosemide 40 mg x 3). Muscle and skin Na + contents were measured at baseline (BA) by 23 Sodium magnetic resonance imaging ( 23 NaMRI). Urine and serum electrolytes, glomerular filtration rate and the % CD14 + monocytes containing isoLG adducts using flow cytometry were obtained at BA, after salt-loading (HI) and after salt-depletion (LO). All continuous data are displayed as median (interquartile range). Spearman’s correlation was used to test associations. Results: Median age was 54 years (44-55), 60% of subjects were female, screening systolic BP (SBP) was 140 mmHg (134-148), diastolic BP was 88 mmHg (84-99) and BMI was 35 kg/m 2 (30-39). SBP response to salt-depletion (salt-sensitivity index, SSI) varied from -13.8 to +1.8 mmHg. %isoLG + CD14 + cells were 48 (27-65) at BA, 55 (31-56) at HI, and 70 (33-72) at LO (p=0.594, by the Kruskal-Wallis test). The correlation between SSI and delta (Δ) %isoLG LO minus HI, was 0.86, [95% confidence interval (CI), -0.07-0.99] which may suggest conclusively as we gather more data that the greater the SSI, the larger the decrease in isoLGs by salt depletion. Muscle Na + content correlated with 24h urine Na + (BA) (r=0.90, 95% CI, 0.11-0.99), however, the correlation with BP, SSI or isoLGs was inconclusive, potentially due to the small sample size. Skin Na + content correlated with baseline %CD14IsoLG + (r=0.91; 95% CI, 0.12-0.99). Conclusions: Na + intake is a component of the determinants of muscle Na + . Skin Na + is associated with increased isoLGs in monocytes, a marker of immune cell activation. Variability in ΔCD14isoLG may serve as a biomarker for SS of BP in humans.

Long-Term Impacts of Partial Afforestation on Water and Salt Dynamics of an Intermittent Catchment under Climate Change

Soil salinization is a major environmental issue in arid and semi-arid regions, and has been accelerated in some areas by removal of native vegetation cover. Partial afforestation can be a practical mitigation strategy if efficiently integrated with farms and pastures. Using an integrated surface-subsurface hydrological model, this study evaluates the water and salt dynamics and soil salinization conditions of a rural intermittent catchment in the semi-arid climate of southeast Australia subjected to four different partial afforestation configurations under different climate change scenarios, as predicted by several general circulation models. The results show that the locations of afforested areas can induce a retarding effect in the outflow of groundwater salt, with tree planting at lower elevations showing the steadier salt depletion rates. Moreover, except for the configuration with trees planted near the outlet of the catchment, the streamflow is maintained under all other configurations. It appears that under both Representative Concentration Pathways considered (RCP 4.5 and RCP 8.5), the Hadley Centre Global Environmental Model represents the fastest salt export scheme, whereas the Canadian Earth System Model and the Model for Interdisciplinary Research on Climate represent the slowest salt export scheme. Overall, it is found that the location of partial afforestation generally plays a more significant role than the climate change scenarios.

Time-Domain Reflectometry (TDR) Monitoring at a Lab Scale of Aerobic Biological Processes in a Soil Contaminated by Diesel Oil

This study aims to monitor the biological processes ongoing in a hydrocarbon polluted soil. The experiments were carried out at a laboratory scale by measuring the evolution of its geophysical electromagnetic parameters. Time-domain reflectometry (TDR) probes were used to measure dielectric permittivity and electrical conductivity in columns of sandy soil artificially contaminated with diesel oil (Voil/Vtot = 0.19). To provide aerobic conditions suitable for the growth of microorganisms, they were hydrated with Mineral Salt Medium for Bacteria. One mesocosm was aerated by injecting air from the bottom of the column, while the other had only natural aeration due to diffusion of air through the soil itself. The monitoring lasted 105 days. Geophysical measurements were supported by microbiological, gas chromatographic analyses, and scanning electron microscope (SEM) images. Air injection heavily influenced the TDR monitoring, probably due to the generation of air bubbles around the probe that interfered with the probe–soil coupling. Therefore, the measurement accuracy of geophysical properties was dramatically reduced in the aerated system, although biological analyses showed that aeration strongly supports microbial activity. In the non-aerated system, a slight (2%) linear decrease of dielectric permittivity was observed over time. Meanwhile, the electrical conductivity initially decreased, then increased from day 20 to day 45, then decreased again by about 30%. We compared these results with other researches in recent literature to explain the complex biological phenomena that can induce variations in electrical parameters in a contaminated soil matrix, from salt depletion to pore clogging.

Prevention of Contrast-Induced Nephropathy through a Knowledge of Its Pathogenesis and Risk Factors

Contrast-induced nephropathy (CIN) is an iatrogenic acute renal failure (ARF) occurring after the intravascular injection of iodinated radiographic contrast media. During the past several years, in many patients undergoing computed tomography, iodinated contrast media have not been used for the fear of ARF, thereby compromising the diagnostic procedure. But recent studies have demonstrated that CIN is rarely occurring in patients with normal renal function and that preexisting chronic renal failure and/or diabetes mellitus represent(s) predisposing condition(s) for its occurrence. After the description of CIN and its epidemiology and pathophysiology, underlying the important role played by dehydration and salt depletion, precautions for prevention of CIN are listed, suggested, and discussed. Maximum priority has to be given to adequate hydration and volume expansion prior to radiographic procedures. Other important precautions include the need for monitoring renal function before, during, and after contrast media injection, discontinuation of potentially nephrotoxic drugs, use of either iodixanol or iopamidol at the lowest dosage possible, and administration of antioxidants. A long list of references is provided that will enable readers a deep evaluation of the topic.

Abstract 400: Angiotensin II Triggers the Same Pressor Mechanisms in Salt-sensitive Hypertension and During Salt Depletion

Salt restriction or blood volume decline activates the renin-angiotensin (Ang) system to protect against short- and long-term drops in blood pressure (BP). Excess dietary salt and salt retention, however, activates CNS Ang II-mediated mechanisms that elevate BP. We tested the idea that the same CNS-regulated downstream mechanisms modulate total peripheral vascular resistance (TPR) under both conditions. Protocol 1: normal Sprague-Dawley (SD) rats were fed either normal salt (NS, 0.4% NaCl) or low salt (LS, 0.1% NaCl) for 2 wks. Protocol 2: SD rats were infused subcutaneously with vehicle (V, saline) or Ang II (A, 150 ng/kg/min); some V and some A rats were fed NS, and the others were fed high salt (HS, 2% NaCl) for 2 wks. At the end of both protocols, intra-arterial BP was recorded and blood was drawn for endogenous ouabain (EO) determination by radioimmunoassay and multi-stage mass spectroscopy. Aortae and mesenteric arteries were harvested for protein immunoblots to determine arterial smooth muscle (ASM) expression of Na/Ca exchanger-1 (NCX1), a key Ca 2+ transporter. LS did not affect mean BP (87±2 vs 91±4 mm Hg, n =6 each), but did raise plasma EO (0.70±0.19 vs 0.21±0.02 nM, P < 0.05) and increase ASM NCX1 expression 1.52-fold. Ang II infusion and, especially, HS + Ang II, increased mean BP (110±4 and 124±3 mm Hg, P <0.05 and P <0.001, respectively, vs 100±4 mm Hg, n =5-8) and plasma EO (0.53±0.31 and 1.31±0.72 nM, respectively, both P<0.05, vs 0.07±0.02 nM, n =5-8). HS + Ang II also increased ASM NCX1 expression 1.91-fold. HS + Ang II, as well as LS also increased expression of SERCA2 and TRPC6, two other ASM Ca 2+ transporters. Intracerebroventricular Ang II also raises plasma EO and increases expression of the 3 Ca 2+ transporters in ASM; thus, the CNS controls this pressor pathway (Hamlyn et al., Hypertension 60 (3, Suppl.):e419, 2012). The new data reveal that both LS and HS activate the same downstream mechanisms: they elevate plasma EO and ASM Ca 2+ transporter expression. The increases in ASM Ca 2+ transporter expression, and enhanced sympathetic drive, should increase arterial tone and raise BP during salt excess, and minimize BP decline. We conclude that these fundamental mechanisms contribute to “whole body autoregulation” in the long-term control of TPR and BP.