The role of thymosin-?4 in kidney disease

Therapies which modulate inflammation and fibrosis have the potential to reduce the morbidity and mortality associated with chronic kidney disease. A promising avenue may be manipulating thymosin-?4, a naturally-occurring peptide which is the major G-actin sequestering protein in mammalian cells and a regulator of inflammation and fibrosis. Thymosin-?4 is already being tested in clinical trials for heart disease and wound healing. In this editorial, we outline the evidence that thymosin-?4 may also have therapeutic benefit in chronic kidney disease

L-citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans

This is the author accepted manuscript. The final version is available from the American Physiological Society via the DOI in this record.The purpose of this study was to compare the effects of L-citrulline (CIT) and L-arginine (ARG) supplementation on nitric oxide (NO) biomarkers, pulmonary O2 uptake (VO2) kinetics and exercise performance. In a randomised, placebo-controlled, cross-over study, ten healthy adult males completed moderate- and severe-intensity cycling exercise on days 6 and 7 of a 7 day supplementation period with placebo (PLA), 6 g•day(-1) of ARG and 6 g•day(-1) of CIT. Compared to PLA, plasma [ARG] was increased by a similar magnitude with ARG and CIT supplementation, but plasma [CIT] was only increased (P0.05). In conclusion, these results suggest that short-term CIT, but not ARG, supplementation can improve blood pressure, VO2 kinetics and exercise performance in healthy adults

Frequency of Th17 CD20+ cells in the peripheral blood of rheumatoid arthritis patients is higher compared to healthy subjects

addresses: Peninsula Medical School, University of Exeter, Heavitree Road, Exeter EX1 2LU, UK. [email protected]: PMCID: PMC3334661types: Journal Article; Research Support, Non-U.S. Gov'tRheumatoid arthritis (RA) is considered a T cell driven autoimmune disease, therefore, the ability of B cell depleting biologics, e.g., anti-CD20 antibodies, to alleviate RA is unclear. This study examined the proportions of IL-17-secreting lymphocytes in the blood of healthy subjects and RA patients and determined if Th17 cells belong to a CD20+ subset of T cells

Myeloperoxidase and oxidative stress in rheumatoid arthritis

Objective. To determine whether MPO contributes to oxidative stress and disease activity in RA and whether it produces hypochlorous acid in SF. Methods. Plasma and where possible SF were collected from 77 RA patients while 120 healthy controls supplied plasma only. MPO and protein carbonyls were measured by ELISAs. 3-Chlorotyrosine in proteins and allantoin in plasma were measured by mass spectrometry. Results. Plasma MPO concentrations were significantly higher in patients with RA compared with healthy controls [10.8 ng/ml, inter-quartile range (IQR): 7.214.2; P < 0.05], but there was no significant difference in plasma MPO protein concentrations between RA patients with high disease activity (HDA; DAS-28 >3.2) and those with low disease activity (LDA; DAS-28 43.2) (HDA 27.9 ng/ml, 20.234.1 vs LDA 22.1 ng/ml, 16.934.9; P > 0.05). There was a significant relationship between plasma MPO and DAS-28 (r = 0.35; P = 0.005). Plasma protein carbonyls and allantoin were significantly higher in patients with RA compared with the healthy controls. MPO protein was significantly higher in SF compared with plasma (median 624.0 ng/ml, IQR 258.42433.0 vs 30.2 ng/ml, IQR 25.150.9; P < 0.0001). The MPO present in SF was mostly active. 3-Chlorotyrosine, a specific biomarker of hypochlorous acid, was present in proteins from SF and related to the concentration of MPO (r = 0.69; P = 0.001). Protein carbonyls in SF were associated with MPO protein concentration (r = 0.40; P = 0.019) and 3-chlorotyrosine (r = 0.66; P = 0.003). Conclusion. MPO is elevated in patients with RA and promotes oxidative stress through the production of hypochlorous acid

Improvement in blood pressure after short-term inorganic nitrate supplementation is attenuated in cigarette smokers compared to non-smoking controls

Dietary supplementation with inorganic nitrate (NO3-) has been reported to improve cardiovascular health indices in healthy adults. Cigarette smoking increases circulating thiocyanate (SCN-), which has been suggested to competitively inhibit salivary nitrate (NO3-) uptake, a rate-limiting step in dietary NO3 - metabolism. Therefore, this study tested the hypothesis that dietary NO3 - supplementation would be less effective at increasing the circulating plasma nitrite concnetration ([NO2-]) and lowering blood pressure in smokers (S)compared to non-smokers (NS). Nine healthy smokers and eight healthy non-smoking controls reported to the laboratory at baseline (CON) and following six day supplementation periods with 140 ml∙day-1 NO3--rich (8.4 mmol NO3 -∙day-1; NIT) and NO3--depleted (0.08mmol NO3 -∙day-1; PLA) beetroot juice in a cross-over experiment. Plasma and salivary [SCN-] were elevated in smokers compared to non-smokers in all experimental conditions (P<0.05). Plasma and salivary [NO3 -] and nitrite ([NO2-]) were elevated in the NIT condition compared to CON and PLA conditions in smokers and non-smokers (P<0.05). However, the change in salivary [NO3-] (S: 3.5 ± 2.1 vs. NS: 7.5 ± 4.4 mM), plasma [NO3-] (S: 484 ± 198 vs. NS: 802 ± 199 μM) and plasma [NO2-] (S: 218 ± 128 vs. NS: 559 ± 419 nM) between the CON and NIT conditions was lower in the smokers compared to the non-smokers (P<0.05). Salivary [NO2 -] increased above CON to a similar extent with NIT in smokers and nonsmokers (P>0.05). Systolic blood pressure was lowered compared to PLA with NIT in nonsmokers (P0.05). These findings suggest that dietary NO3- metabolism is compromised in smokers leading to an attenuated blood pressure reduction compared to non-smokers after NO3- supplementation. These observations may provide novel insights into the cardiovascular risks associated with cigarette smoking and suggest that this population may be less likely to benefit from improved cardiovascular health if they increase dietary NO3 - intake

Two weeks of watermelon juice supplementation improves nitric oxide bioavailability but not endurance exercise performance in humans

This study tested the hypothesis that watermelon juice supplementation would improve nitric oxide bioavailability and exercise performance. Eight healthy recreationally-active adult males reported to the laboratory on two occasions for initial testing without dietary supplementation (control condition). Thereafter, participants were randomly assigned, in a cross-over experimental design, to receive 16 days of supplementation with 300 mL·day-1 of a watermelon juice concentrate, which provided ~3.4g L-citrulline·day-1 and an apple juice concentrate as a placebo. Participants reported to the laboratory on days 14 and 16 of supplementation to assess the effects of the interventions on blood pressure, plasma [Lcitrulline], plasma [L-arginine], plasma [nitrite], muscle oxygenation and time-to-exhaustion during severe-intensity exercise. Compared to control and placebo, plasma [L-citrulline] (29 ± 4, 22 ± 6 and 101 ± 23 μM), [L-arginine] (74 ± 9, 67 ± 13 and 116 ± 9 μM) and [nitrite] (102 ± 29, 106 ± 21 and 201 ± 106 nM) were higher after watermelon juice supplementation (P<0.01). However, systolic blood pressure was higher in the watermelon juice (130 ± 11) and placebo (131 ± 9) conditions compared to the control condition (124 ± 8 mmHg; P<0.05). The skeletal muscle oxygenation index during moderate-intensity exercise was greater in the watermelon juice condition than the placebo and control conditions (P<0.05), but time-to-exhaustion during the severe-intensity exercise test (control: 478 ± 80, placebo: 539 ± 108, watermelon juice: 550 ± 143 s) was not significantly different between conditions (P<0.05). In conclusion, while watermelon juice supplementation increased baseline plasma [nitrite] and improved muscle oxygenation during moderate-intensity exercise, it increased resting blood pressure and did not improve time-to-exhaustion during severe-intensity exercise. These findings do not support the use of watermelon juice supplementation as a nutritional intervention to lower blood pressure or improve endurance exercise performance in healthy adults

Influence of iodide ingestion on nitrate metabolism and blood pressure following short-term dietary nitrate supplementation in healthy normotensive adults

Uptake of inorganic nitrate (NO3−) into the salivary circulation is a rate-limiting step for dietary NO3− metabolism in mammals. It has been suggested that salivary NO3− uptake occurs in competition with inorganic iodide (I−). Therefore, this study tested the hypothesis that I− supplementation would interfere with NO3− metabolism and blunt blood pressure reductions after dietary NO3− supplementation. Nine healthy adults (4 male, mean ± SD, age 20 ± 1 yr) reported to the laboratory for initial baseline assessment (control) and following six day supplementation periods with 140 mL·day−1 NO3−-rich beetroot juice (8.4 mmol NO3−·day−1) and 198 mg potassium gluconate·day−1 (nitrate), and 140 mL·day−1 NO3−-rich beetroot juice and 450 μg potassium iodide·day−1 (nitrate + iodide) in a randomized, cross-over experiment. Salivary [I−] was higher in the nitrate + iodide compared to the control and NIT trials (P 0.05). Systolic blood pressure was lower than control (112 ± 13 mmHg) in the nitrate (106 ± 13 mmHg) and nitrate + iodide (106 ± 11 mmHg) trials (P 0.05). In conclusion, co-ingesting NO3− and I− perturbed salivary NO3− uptake, but the increase in salivary and plasma [NO2−] and the lowering of blood pressure were similar compared to NO3− ingestion alone. Therefore, increased dietary I− intake, which is recommended in several countries worldwide as an initiative to offset hypothyroidism, does not appear to compromise the blood pressure reduction afforded by increased dietary NO3− intake

Lowering of blood pressure after nitrate-rich vegetable consumption is abolished with the co-ingestion of thiocyanate-rich vegetables in healthy normotensive males

A diet rich in vegetables is known to provide cardioprotection. However, it is unclear how the consumption of different vegetables might interact to influence vascular health. This study tested the hypothesis that nitrate-rich vegetable consumption would lower systolic blood pressure but that this effect would be abolished when nitrate-rich and thiocyanate-rich vegetables are co-ingested. On four separate occasions, and in a randomised cross-over design, eleven healthy males reported to the laboratory and consumed a 750 mL vegetable smoothie that was either: low in nitrate (~ 0.3 mmol) and thiocyanate (~ 5 μmol), low in nitrate and high in SCN- (~ 72 μmol), high in nitrate (~ 4 mmol) and low in SCN- and high in nitrate and SCN-. Blood pressure as well as plasma and salivary [thiocyanate], [nitrate] and [nitrite] were assessed before and 3 hours after smoothie consumption. Plasma [nitrate] and [nitrite] and salivary [nitrate] were not different after consuming the two high-nitrate smoothies, but salivary [nitrite] was higher after consuming the high-nitrate low-thiocyanate smoothie (1183 ± 625 µM) compared to the high-nitrate high-thiocyanate smoothie (941 ± 532 µM; P<0.001). Systolic blood pressure was only lowered after consuming the high-nitrate low-thiocyanate smoothie (-3 ± 5 mmHg; P<0.05). The acute consumption of vegetables high in nitrate and low in thiocyanate lowered systolic blood pressure. However, when the same dose of nitrate-rich vegetables was co-ingested with thiocyanate-rich vegetables the increase in salivary [nitrite] was smaller and systolic blood pressure was not lowered. These findings might have implications for optimising dietary guidelines aimed at improving cardiovascular health

A high-sensitivity electrochemiluminescence-based ELISA for the measurement of the oxidative stress biomarker, 3-nitrotyrosine, in human blood serum and cells

The generation of 3-nitrotyrosine, within proteins, is a post-translational modification resulting from oxidative or nitrative stress. It has been suggested that this modification could be used as a biomarker for inflammatory diseases. Despite the superiority of mass spectrometry-based determinations of nitrotyrosine, in a high-throughput clinical setting the measurement of nitrotyrosine by an enzyme-linked immunosorbent assay (ELISA) is likely to be more cost-effective. ELISAs offer an alternative means to detect nitrotyrosine, but many commercially available ELISAs are insufficiently sensitive to detect nitrotyrosine in healthy human serum. Here, we report the development, validation and clinical application of a novel electrochemiluminescence-based ELISA for nitrotyrosine which provides superior sensitivity (e.g. a 50-fold increase in sensitivity compared with one of the tested commercial colorimetric ELISAs). This nitrotyrosine ELISA has the following characteristics: a lower limit of quantitation of 0.04 nM nitrated albumin equivalents; intra- and inter-assay coefficients of variation of 6.5% and 11.3%, respectively; a mean recovery of 106 ± 3% and a mean linearity of 0.998 ± 0.001. Far higher nitration levels were measured in normal human blood cell populations when compared to plasma. Mass spectrometry was used to validate the new ELISA method. The analysis of the same set of chemically modified albumin samples using the ELISA method and mass spectrometry showed good agreement for the relative levels of nitration present in each sample. The assay was applied to serum samples from patients undergoing elective surgery which induces the human inflammatory response. Matched samples were collected before and one day after surgery. An increase in nitration was detected following surgery (median (IQR): 0.59 (0.00–1.34) and 0.97 (0.00–1.70) nitrotyrosine (fmol of nitrated albumin equivalents/mg protein) for pre- and post-surgery respectively. The reported assay is suitable for nitrotyrosine determination in patient serum samples, and may also be applicable as a means to determine oxidative stress in primary and cultured cell populations