Is Low Serum Klotho Level Associated with Alterations in Coronary Flow Reserve?

Klotho is highly expressed in the chief sites of regulated potassium secretion, and it is stimulated by potassium intake

Klotho regulates many pathways in the aging process, but it remains unclear how it is physiologically regulated. Because Klotho is synthesized, cleaved, and released from the kidney; activates the chief urinary K+ secretion channel (ROMK) and stimulates urinary K+ secretion, we explored if Klotho protein is regulated by dietary K+ and the potassium-regulatory hormone, Aldosterone. Klotho protein along the nephron was evaluated in humans and in wild-type (WT) mice; and in mice lacking components of Aldosterone signaling, including the Aldosterone-Synthase KO (AS-KO) and the Mineralocorticoid-Receptor KO (MR-KO) mice. We found the specific cells of the distal nephron in humans and mice that are chief sites of regulated K+ secretion have the highest Klotho protein expression along the nephron. WT mice fed K+-rich diets increased Klotho expression in these cells. AS-KO mice exhibit normal Klotho under basal conditions but could not upregulate Klotho in response to high-K+ intake in the K+-secreting cells. Similarly, MR-KO mice exhibit decreased Klotho protein expression. Together, i) Klotho is highly expressed in the key sites of regulated K+ secretion in humans and mice, ii) In mice, K+-rich diets increase Klotho expression specifically in the potassium secretory cells of the distal nephron, iii) Aldosterone signaling is required for Klotho response to high K+ intake.

Circulating Biomarkers in Coronary Microvascular Dysfunction

Coronary microvascular dysfunction is an underdiagnosed pathologic process that is associated with adverse clinical outcomes. Biomarkers, molecules measurable in the blood, could inform the clinician by aiding in the diagnosis and management of coronary microvascular dysfunction. We present an updated review of circulating biomarkers in coronary microvascular dysfunction representing key pathologic processes, including inflammation, endothelial dysfunction, oxidative stress, coagulation, and other mechanisms.

Patients with Earlobe Crease May Associate with Lower Concentration of the Age-Suppressing Hormone Klotho

Objective

Earlobe crease (ELC) has been considered as a skin sign of atherosclerosis, and its pathophysiological mechanism is still unclear. Our study aims to test the hypothesis that ELC patients with lower serum levels of the age-suppressing hormone Klotho, which is not only associated with premature aging but also with endothelial dysfunction, may be associated with atherosclerosis.

Methods

A total of 135 patients aged 40–68 years underwent coronary angiography. According to the presence or absence of coronary heart disease (CAD) and ELC, they were divided into three groups: CAD group and ELC group (ELC group, n = 45); no ELC group (non-ELC group, n = 45). There was no ELC or CAD in the control group (control group, n = 45). Serum Klotho concentration was obtained by enzyme-linked immunosorbent assay (ELISA).

Results

The Klotho level in the ELC group was 365.6 ± 38.1 pg/mL, while the Klotho level in the non-ELC group was 568.8 ± 44.9 pg/mL. It is worth noting that the Klotho level of the ELC group was significantly lower than that of the non-ELC group (P < 0.001). The serum Klotho level of the control group was higher than that of the non-ELC group (593.3±45.3 vs 568.8±44.9 pg/mL, P = 0.702), but the difference was not statistically significant. Multiple logistic regression analysis showed that the Klotho level is a parameter that affects the appearance of ELC.

Conclusion

Serum Klotho levels were considerably lower in patients with ELC. We concluded that the perturbations of Klotho in patients might be associated with ELC and with CAD.

Increased Plasma Level of Longevity Protein Klotho as a Potential Indicator of Cognitive Function Preservation in Patients With Schizophrenia

Cognitive impairments are a core feature of schizophrenia. Klotho is an anti-aging protein with demonstrated cognitive-enhancing effects on the brain. The purpose of this study was to investigate the differences in levels of plasma klotho between patients with schizophrenia and healthy controls, as well as the relationship between klotho level and cognitive function in patients. Forty patients with schizophrenia and 40 gender- and age-matched healthy individuals were recruited. Positive and Negative Syndrome Scale (PANSS) was used to assess the psychopathology of patients. A neuropsychological battery was performed to evaluate the cognitive function of participants. Plasma klotho was measured using enzyme-linked immunosorbent assay. We show that patients with schizophrenia performed worse in the neurocognitive tests than the healthy controls. The levels of plasma klotho were significantly higher in schizophrenia patients than in healthy controls (p < 0.001). In patients, plasma klotho levels were positively correlated with cognitive function with regard to attention (p = 0.010), working memory (p < 0.001), verbal memory (p = 0.044), executive function (p < 0.001), and composite cognitive score (p < 0.001). Stepwise linear regression analysis shows that executive function had the highest correlation with plasma klotho levels (β = 0.896, t = 8.290, p < 0.001). Collectively, these results indicate that anti-aging protein klotho may be implicated in the pathogenesis of schizophrenia, and increased klotho may act as a compensatory factor for the preservation of cognitive function in schizophrenia. Further studies are needed to investigate the dynamic changes of klotho and the mechanisms by which klotho modulates cognition in schizophrenia.

Effects of aging on coronary flow reserve in patients with no evidence of myocardial perfusion abnormality

Coronary flow reserve (CFR) reflects the functional capacity of microcirculation to adapt to blood demand during increased cardiac work. We tested the hypothesis that aging had impacts on coronary flow velocities and CFR in patients with no evidence of myocardial perfusion abnormality on single photon emission computed tomography (SPECT). Seventy-six patients undergoing transthoracic Doppler echocardiography with no evidence of myocardial perfusion abnormality on SPECT were enrolled in this study. CFR was defined as the ratio of hyperemic to resting peak diastolic coronary flow velocity. Patients were divided into the three groups based on age: 17 patients aged less than 70 years (Group I), 38 patients aged 70-79 years (Group II), and 21 patients aged 80 years or more (Group III). Compared with Group I, CFR was significantly lower in Group II (p < 0.01) and Group III (p < 0.01). Multivariate linear regression analysis showed that female (β = - 0.26, p = 0.03), cigarette smoking (β = - 0.32, p = 0.004), hemoglobin level (β = - 0.40, p = 0.001) and LV mass index (β = 0.24, p = 0.03) were determinants for resting coronary flow velocity. On the other hand, age (β = -0.30, p = 0.008), hemoglobin level (β = -0.47, p < 0.001) and LV mass index (β = 0.24, p = 0.04) were determinants for hyperemic coronary flow velocity. Age was only determinant for CFR (β = -0.48, p < 0.001). Our data suggested that that aging had a decreased effect on hyperemic coronary flow velocity rather than resting coronary flow velocity, and was further associated with impaired CFR in patients with no evidence of myocardial perfusion abnormality.