Abstract-Angiotensin (Ang)-converting enzyme 2 (ACE2) cleaves Ang II to form Ang-(1-7). Here we examined whether soluble human recombinant ACE2 (rACE2) can efficiently lower Ang II and increase Ang-(1-7) and whether rACE2 can prevent hypertension caused by Ang II infusion as a result of systemic versus local mechanisms of ACE2 activity amplification. rACE2 was infused via osmotic minipumps for 3 days in conscious mice or acutely in anesthetized mice. rACE2 caused a dose-dependent increase in serum ACE2 activity but had no effect on kidney or cardiac ACE2 activity. After Ang II infusion (40 pmol/min), rACE2 (1 mg/kg per day) resulted in normalization of systolic blood pressure and plasma Ang II. In acute studies, rACE2 (1 mg/kg) prevented the rapid hypertensive effect of Ang II (0.2 mg/kg), and this was associated with both a decrease in Ang II and an increase in Ang-(1-7) in plasma. Moreover, during infusion of Ang II, the effect of rACE2 on blood pressure was unaffected by a specific Ang-(1-7) receptor blocker, A779 (0.2 mg/kg), and infusing supraphysiologic levels of Ang-(1-7) (0.2 mg/kg) had no effect on blood pressure. We conclude that, during Ang II infusion, rACE2 effectively degrades Ang II and, in the process, normalizes blood pressure. The mechanism of rACE2 action results from an increase in systemic, not tissue, ACE2 activity and the lowering of plasma Ang II rather than the attendant increase in Ang-(1-7). Increasing ACE2 activity may provide a new therapeutic target in states of Ang II overactivity by enhancing its degradation, an approach that differs from the current focus on blocking Ang II formation and action. (Hypertension. 2010;55:90-98.)A ngiotensin (Ang)-converting enzyme 2 (ACE2) is the only known enzymatically active homologue of Angconverting enzyme (ACE). 1-3 ACE2 is a monocarboxypeptidase that removes single amino acids from the C terminus of its substrates. 1-3 ACE, by contrast, is a peptidyl dipeptidase that removes C-terminal dipeptides. ACE promotes Ang II formation from Ang I, whereas ACE2 converts Ang I to Ang-(1-9) and Ang II to Ang-(1-7), respectively. 1-3 The catalytic efficiency of human ACE2 is 400-fold higher with Ang II than with Ang I as a substrate. 3 Moreover, because the product of Ang I cleavage by ACE2, Ang-(1-9), has no known biological action, it seems logical to postulate that cleavage of Ang II to Ang-(1-7) is a major action of ACE2.There is increasing interest in the possible renoprotective effects of ACE2. 4 -9 A protective effect of ACE2 against acute lung injury 10,11 and cardiovascular disease 12,13 has also been proposed. Ang-(1-7) is a blood-vessel dilator identified as an endogenous ligand for a G protein-coupled Mas receptor. 14 -16 Ang II, among its many other known biological effects, is a potent vasoconstrictor and promotes renal sodium retention, both of which lead to hypertension.The blockade of steps leading to Ang II formation using ACE inhibitors and renin inhibitors or blocking the action of Ang II on the Ang II type 1 receptor using specific an...

ObjectiveGlycans attached to the Fc portion of IgG are important modulators of IgG effector functions. Interindividual differences in IgG glycome composition are large and they associate strongly with different inflammatory and autoimmune diseases. IKZF1, HLA–DQ2A/B, and BACH2 genetic loci that affect IgG glycome composition show pleiotropy with systemic lupus erythematosus (SLE), indicating a potentially causative role of aberrant IgG glycosylation in SLE. We undertook this large multicenter case–control study to determine whether SLE is associated with altered IgG glycosylation.MethodsUsing ultra‐performance liquid chromatography analysis of released glycans, we analyzed the composition of the IgG glycome in 261 SLE patients and 247 matched controls of Latin American Mestizo origin (the discovery cohort) and in 2 independent replication cohorts of different ethnicity (108 SLE patients and 193 controls from Trinidad, and 106 SLE patients and 105 controls from China).ResultsMultiple statistically significant differences in IgG glycome composition were observed between patients and controls. The most significant changes included decreased galactosylation and sialylation of IgG (which regulate proinflammatory and antiinflammatory actions of IgG) as well as decreased core fucose and increased bisecting N‐acetylglucosamine (which affect antibody‐dependent cell‐mediated cytotoxicity).ConclusionThe IgG glycome in SLE patients is significantly altered in a way that decreases immunosuppressive action of circulating immunoglobulins. The magnitude of observed changes is associated with the intensity of the disease, indicating that aberrant IgG glycome composition or changes in IgG glycosylation may be an important molecular mechanism in SLE.

Small molecules are extensively metabolized and cleared by the kidney. Changes in serum metabolite concentrations may result from impaired kidney function and can be used to estimate filtration (e.g., the established marker creatinine) or may precede and potentially contribute to CKD development. Here, we applied a nontargeted metabolomics approach using gas and liquid chromatography coupled to mass spectrometry to quantify 493 small molecules in human serum. The associations of these molecules with GFR estimated on the basis of creatinine (eGFRcr) and cystatin C levels were assessed in #1735 participants in the KORA F4 study, followed by replication in 1164 individuals in the TwinsUK registry. After correction for multiple testing, 54 replicated metabolites significantly associated with eGFRcr, and six of these showed pairwise correlation (r$0.50) with established kidney function measures: C-mannosyltryptophan, pseudouridine, N-acetylalanine, erythronate, myo-inositol, and N-acetylcarnosine. Higher C-mannosyltryptophan, pseudouridine, and O-sulfo-L-tyrosine concentrations associated with incident CKD (eGFRcr ,60 ml/min per 1.73 m 2 ) in the KORA F4 study. In contrast with serum creatinine, C-mannosyltryptophan and pseudouridine concentrations showed little dependence on sex. Furthermore, correlation with measured GFR in 200 participants in the AASK study was 0.78 for both C-mannosyltryptophan and pseudouridine concentration, and highly significant associations of both metabolites with incident ESRD disappeared upon adjustment for measured GFR. Thus, these molecules may be alternative or complementary markers of kidney function. In conclusion, our study provides a comprehensive list of kidney function-associated metabolites and highlights potential novel filtration markers that may help to improve the estimation of GFR. 27: 117527: -118827: , 201627: . doi: 10.1681 Metabolites are small organic molecules involved in both systemic and organ-specific metabolic processes. The kidney receives about 20% of the cardiac output and is one of the most important excretory organs for a wide variety of metabolites, many of which are freely filtered as solutes of small molecular size. In addition, many metabolites are actively secreted into or reabsorbed from the tubular lumen. The kidney also has a role in the generation and metabolism of some metabolites such as amino acids. Changes in blood metabolite J Am Soc Nephrol

Patients with chronic kidney disease (CKD) are at an increased risk of premature mortality, mainly from cardiovascular causes. The association between CKD on hemodialysis and accelerated atherosclerosis was described >40 years ago. However, more recently, it has been suggested that the increase in atherosclerosis risk is actually observed in early CKD stages, remaining stable thereafter. In this regard, interventions targeting the pathogenesis of atherosclerosis, such as statins, successful in the general population, have failed to benefit patients with very advanced CKD. This raises the issue of the relative contribution of atherosclerosis versus other forms of cardiovascular injury such as arteriosclerosis or myocardial injury to the increased cardiovascular risk in CKD. In this review, the pathophysiogical contributors to atherosclerosis in CKD that are shared with the general population, or specific to CKD, are discussed. The NEFRONA study (Observatorio Nacional de Atherosclerosis en NEFrologia) prospectively assessed the prevalence and progression of subclinical atherosclerosis (plaque in vascular ultrasound), confirming an increased prevalence of atherosclerosis in patients with moderate CKD. However, the adjusted odds ratio for subclinical atherosclerosis increased with CKD stage, suggesting a contribution of CKD itself to subclinical atherosclerosis. Progression of atherosclerosis was closely related to CKD progression as well as to the baseline presence of atheroma plaque, and to higher phosphate, uric acid, and ferritin and lower 25(OH) vitamin D levels. These insights may help design future clinical trials of stratified personalized medicine targeting atherosclerosis in patients with CKD. Future primary prevention trials should enroll patients with evidence of subclinical atherosclerosis and should provide a comprehensive control of all known risk factors in addition to testing any additional intervention or placebo.

IntroductionSeveral circulating metabolites derived from bacterial protein fermentation have been found to be inversely associated with renal function but the timing and disease severity is unclear. The aim of this study is to explore the relationship between indoxyl-sulfate, p-cresyl-sulfate, phenylacetylglutamine and gut-microbial profiles in early renal function decline.ResultsIndoxyl-sulfate (Beta(SE) = -2.74(0.24); P = 8.8x10-29), p-cresyl-sulfate (-1.99(0.24), P = 4.6x10-16), and phenylacetylglutamine(-2.73 (0.25), P = 1.2x10-25) were inversely associated with eGFR in a large population base cohort (TwinsUK, n = 4439) with minimal renal function decline. In a sub-sample of 855 individuals, we analysed metabolite associations with 16S gut microbiome profiles (909 profiles, QIIME 1.7.0). Three Operational Taxonomic Units (OTUs) were significantly associated with indoxyl-sulfate and 52 with phenylacetylglutamine after multiple testing; while one OTU was nominally associated with p-cresyl sulfate. All 56 microbial members belong to the order Clostridiales and are represented by anaerobic Gram-positive families Christensenellaceae, Ruminococcaceae and Lachnospiraceae. Within these, three microbes were also associated with eGFR.ConclusionsOur data suggest that indoxyl-sulfate, p-cresyl-sulfate and phenylacetylglutamine are early markers of renal function decline. Changes in the intestinal flora associated with these metabolites are detectable in early kidney disease. Future efforts should dissect this relationship to improve early diagnostics and therapeutics strategies.

Circulating ACE2 and ACE activities can be measured in human EDTA-plasma samples with zinc added to recover enzymatic activity. In a CKD population without previous history of CV disease, ACE2 activity from human EDTA-plasma samples directly correlated with the classical CV risk factors namely older age, diabetes and male gender. Our data suggest that circulating ACE2 is altered in CKD patients at risk for CV event.

BackgroundAcute kidney injury (AKI) is a life-threatening complication of severe rhabdomyolysis. This study was conducted to assess risk factors for AKI and to develop a risk score for early prediction.MethodsRetrospective observational cohort study with a 9-year follow-up, carried out in an acute-care teaching-affiliated hospital. A total of 126 patients with severe rhabdomyolysis defined as serum creatine kinase (CK) > 5,000 IU/L fulfilled the inclusion criteria. Univariate and logistic regression analyses were performed to determine risk factors for AKI. Based on the values obtained for each variable, a risk score and prognostic probabilities were estimated to establish the risk for developing AKI.ResultsThe incidence of AKI was 58%. Death during hospitalization was significantly higher among patients with AKI, compared to patients without AKI (19.2% vs 3.6%, p = 0.008). The following variables were independently associated with AKI: peak CK (odds ratio [OR] 4.9, 95%CI 1.4-16.8), hypoalbuminemia (< 33 mg/dL, [OR 5.1, 95%CI 1.4-17-7]), metabolic acidosis (OR 5.3, 95%CI 1.4-20.3), and decreased prothrombin time (OR 4.4, 95% CI 1.3-14.5). A risk score for AKI was calculated for each patient, with an OR of 1.72 (95%CI 1.45-2.04). The discrimination value of the predictive model was established by means of a ROC curve, with the area under the curve of 0.871 (p<0.001).ConclusionsThe identification of independent factors associated with AKI and a risk score for early prediction of this complication in patients with severe rhabdomyolysis may be useful in clinical practice, particularly to implement early preventive measures.

The World Health Organization has declared the SARS-CoV-2 infection (COVID-19) outbreak as a Public Health Emergency of International Concern and characterized it as a pandemic. 1,2 Since early March, 2020, the Spanish cases curve started to rise, with more than 177 000 people infected in 6 weeks. 3 The reported fatality-rate in the general population with COVID-19 admitted to a large tertiary Spanish Hospital is 20.7%, 34% in the subgroup of age 70-79 years. 4