Gerarda Navis

Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis

Severe acute respiratory syndrome (SARS) is an acute infectious disease that spreads mainly via the respiratory route. A distinct coronavirus (SARS‐CoV) has been identified as the aetiological agent of SARS. Recently, a metallopeptidase named angiotensin‐converting enzyme 2 (ACE2) has been identified as the functional receptor for SARS‐CoV. Although ACE2 mRNA is known to be present in virtually all organs, its protein expression is largely unknown. Since identifying the possible route of infection has major implications for understanding the pathogenesis and future treatment strategies for SARS, the present study investigated the localization of ACE2 protein in various human organs (oral and nasal mucosa, nasopharynx, lung, stomach, small intestine, colon, skin, lymph nodes, thymus, bone marrow, spleen, liver, kidney, and brain). The most remarkable finding was the surface expression of ACE2 protein on lung alveolar epithelial cells and enterocytes of the small intestine. Furthermore, ACE2 was present in arterial and venous endothelial cells and arterial smooth muscle cells in all organs studied. In conclusion, ACE2 is abundantly present in humans in the epithelia of the lung and small intestine, which might provide possible routes of entry for the SARS‐CoV. This epithelial expression, together with the presence of ACE2 in vascular endothelium, also provides a first step in understanding the pathogenesis of the main SARS disease manifestations. Copyright

Genome-wide association study of blood pressure extremes identifies variant near UMOD associated with hypertension

Hypertension is a heritable and major contributor to the global burden of disease. The sum of rare and common genetic variants robustly identified so far explain only 1%–2% of the population variation in BP and hypertension. This suggests the existence of more undiscovered common variants. We conducted a genome-wide association study in 1,621 hypertensive cases and 1,699 controls and follow-up validation analyses in 19,845 cases and 16,541 controls using an extreme case-control design. We identified a locus on chromosome 16 in the 5′ region of Uromodulin (UMOD; rs13333226, combined P value of 3.6×10−11). The minor G allele is associated with a lower risk of hypertension (OR [95%CI]: 0.87 [0.84–0.91]), reduced urinary uromodulin excretion, better renal function; and each copy of the G allele is associated with a 7.7% reduction in risk of CVD events after adjusting for age, sex, BMI, and smoking status (H.R. = 0.923, 95% CI 0.860–0.991; p = 0.027). In a subset of 13,446 individuals with estimated glomerular filtration rate (eGFR) measurements, we show that rs13333226 is independently associated with hypertension (unadjusted for eGFR: 0.89 [0.83–0.96], p = 0.004; after eGFR adjustment: 0.89 [0.83–0.96], p = 0.003). In clinical functional studies, we also consistently show the minor G allele is associated with lower urinary uromodulin excretion. The exclusive expression of uromodulin in the thick portion of the ascending limb of Henle suggests a putative role of this variant in hypertension through an effect on sodium homeostasis. The newly discovered UMOD locus for hypertension has the potential to give new insights into the role of uromodulin in BP regulation and to identify novel drugable targets for reducing cardiovascular risk.

Common variants near TERC are associated with mean telomere length.

We conducted genome-wide association analyses of mean leukocyte telomere length in 2,917 individuals, with follow-up replication in 9,492 individuals. We identified an association with telomere length on 3q26 (rs12696304, combined P = 3.72 × 10−14) at a locus that includes TERC, which encodes the telomerase RNA component. Each copy of the minor allele of rs12696304 was associated with an ∼75-base-pair reduction in mean telomere length, equivalent to ∼3.6 years of age-related telomere-length attrition.

Sodium intake affects urinary albumin excretion especially in overweight subjects

Objectives.  To examine the relationship between sodium intake and urinary albumin excretion, being an established risk marker for later cardiovascular morbidity and mortality.

Accelerated decline and prognostic impact of renal function after myocardial infarction and the benefits of ACE inhibition : the CATS randomized trial

AIMS Information regarding the cardiorenal axis in patients after a myocardial infarction (MI) is limited. We examined the change in renal function after a first MI, the protective effect of angiotensin converting enzyme (ACE) inhibition and the prognostic value of baseline renal function. METHODS AND RESULTS The study population consisted of 298 patients with a first anterior wall MI who were randomized to the ACE inhibitor captopril or placebo after completion of streptokinase infusion. Renal function, by means of glomerular filtration rate (GFR), was calculated using the Cockroft-Gault equation (GFR(c)). In the placebo group, renal function (GFR(c)) declined by 5.5 min(-1)within 1 year, vs only 0.5 ml min(-1)in the ACE inhibitor group (P<0.05). This beneficial effect of captopril was most pronounced in patients with the most compromised renal function at baseline. The incidence of chronic heart failure (CHF) within 1 year increased significantly with decreasing GFR(c)(divided into tertiles: 24.0, 28.9, and 41.2%; P<0.01). The risk-ratio for GFR(c)<81 ml min(-1)vs >103 mL min(-1)was 1.86 (95% CI 1.11-3.13; P=0.019). CONCLUSIONS Renal function markedly deteriorates after a first MI, but is significantly preserved by ACE inhibition. Furthermore, an impaired baseline renal function adds to the prognostic risk of developing CHF in patients after a first anterior MI.

Implementation of proteomic biomarkers: Making it work

Eur J Clin Invest 2012; 42 (9): 1027–1036

Renal ACE2 expression in human kidney disease

Angiotensin‐converting enzyme 2 (ACE2) is a recently discovered homologue of angiotensin‐converting enzyme (ACE) that is thought to counterbalance ACE. ACE2 cleaves angiotensin I and angiotensin II into the inactive angiotensin 1–9, and the vasodilator and anti‐proliferative angiotensin 1–7, respectively. ACE2 is known to be present in human kidney, but no data on renal disease are available to date. Renal biopsies from 58 patients with diverse primary and secondary renal diseases were studied (hypertensive nephropathy n = 5, IgA glomerulopathy n = 8, minimal change nephropathy n = 7, diabetic nephropathy n = 8, focal glomerulosclerosis n = 5, vasculitis n = 7, and membranous glomerulopathy n = 18) in addition to 17 renal transplants and 18 samples from normal renal tissue. Immunohistochemical staining for ACE2 was scored semi‐quantitatively. In control kidneys, ACE2 was present in tubular and glomerular epithelium and in vascular smooth muscle cells and the endothelium of interlobular arteries. In all primary and secondary renal diseases, and renal transplants, neo‐expression of ACE2 was found in glomerular and peritubular capillary endothelium. There were no differences between the various renal disorders, or between acute and chronic rejection and control transplants. ACE inhibitor treatment did not alter ACE2 expression. In primary and secondary renal disease, and in transplanted kidneys, neo‐expression of ACE2 occurs in glomerular and peritubular capillary endothelium. Further studies should elucidate the possible protective mechanisms involved in the de novo expression of ACE2 in renal disease. Copyright

The emerging role of ACE2 in physiology and disease

The renin–angiotensin–aldosterone system (RAAS) is a key regulator of systemic blood pressure and renal function and a key player in renal and cardiovascular disease. However, its (patho)physiological roles and its architecture are more complex than initially anticipated. Novel RAAS components that may add to our understanding have been discovered in recent years. In particular, the human homologue of ACE (ACE2) has added a higher level of complexity to the RAAS. In a short period of time, ACE2 has been cloned, purified, knocked‐out, knocked‐in; inhibitors have been developed; its 3D structure determined; and new functions have been identified. ACE2 is now implicated in cardiovascular and renal (patho)physiology, diabetes, pregnancy, lung disease and, remarkably, ACE2 serves as a receptor for SARS and NL63 coronaviruses. This review covers available information on the genetic, structural and functional properties of ACE2. Its role in a variety of (patho)physiological conditions and therapeutic options of modulation are discussed. Copyright

Equations to Estimate Creatinine Excretion Rate: The CKD Epidemiology Collaboration

BACKGROUND AND OBJECTIVES Creatinine excretion rate (CER) indicates timed urine collection accuracy. Although equations to estimate CER exist, their bias and precision are untested and none simultaneously include age, sex, race, and weight. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Participants (n = 2466) from three kidney disease trials were randomly allocated into equation development (2/3) and internal validation (1/3) data sets. CER served as the dependent variable in linear regression to develop new equations. Their stability was assessed within the internal validation data set. Among 987 individuals from three additional studies the equations were externally validated and compared with existing equations. RESULTS Mean age was 46 years, 42% were women, and 9% were black. Age, sex, race, weight, and serum phosphorus improved model fit. Two equations were developed, with or without serum phosphorus. In external validation, the new equations showed little bias (mean difference [measured - estimated CER] -0.7% [95% confidence interval -2.5% to 1.0%] and 0.3% [95% confidence interval -2.6% to 3.1%], respectively) and moderate precision (estimated CER within 30% of measured CER among 79% [76% to 81%] and 81% [77% to 85%], respectively). Corresponding numbers within 15% were 51% [48% to 54%] and 54% [50% to 59%]). Compared with existing equations, the new equations had similar accuracy but showed less bias in individuals with high measured CER. CONCLUSIONS CER can be estimated with commonly available variables with little bias and moderate precision, which may facilitate assessment of accuracy of timed urine collections.

Telomere length loss due to smoking and metabolic traits

Human age‐dependent telomere attrition and telomere shortening are associated with several age‐associated diseases and poorer overall survival. The aim of this study was to determine longitudinal leucocyte telomere length dynamics and identify factors associated with temporal changes in telomere length.