Usefulness of the serum creatinine/cystatin C ratio as a blood biomarker for sarcopenia components among age groups in community-dwelling older people: The SONIC study.

AIM: The serum creatinine/cystatin C ratio (CCR) or sarcopenia index is considered a useful marker of muscle mass. However, its usefulness in late-stage older adults remains unclear. We aimed to determine the usefulness of CCR as an indicator of sarcopenia in community-dwelling Japanese adults aged >75 years. METHODS: Our study recruited participants aged 70, 80, and 90 ± 1 years during the baseline years, and included a 3-year follow-up in the Septuagenarians, Octogenarians, Nonagenarians, Investigation with Centenarians study. From 2015 to 2018, 955 participants were eligible: 367 in their 70s, 304 in their 80s, and 284 in their 90s. The diagnostic components of sarcopenia, including "low muscle mass, plus low muscle strength, and/or low physical performance," were evaluated using the bioelectrical impedance analysis-measured skeletal muscle mass index (SMI), handgrip strength, and short physical performance battery (SPPB) score, respectively, in accordance with the Asia Working Group for Sarcopenia 2019 criteria. Separate analyses were performed between each component and CCR, adjusting for sex, body mass index, and other blood biomarkers in each group. RESULTS: The relationship between CCR and sarcopenia components was significant for handgrip strength (ß = 0.21, 0.13, 0.19, and P < 0.0001, =0.0088, <0.0001, for the 70s, 80s, and 90s age groups, respectively); however, it was limited for SMI (ß = 0.14; P = 0.0022, only for the 90s) and not significant for the SPPB score. CONCLUSION: CCR is a limited indicator of sarcopenia in late-stage older adults. Although its association with muscle strength was significant, its relationship with muscle mass and physical performance was less pronounced. Geriatr Gerontol Int 2024; 24: 529-536.

Imaging Biomarker for Early-Stage Alzheimer Disease: Utility of Hippocampal Histogram Analysis of Diffusion Metrics.

BACKGROUND AND PURPOSE: Biomarkers have been required for diagnosing early Alzheimer disease. We assessed the utility of hippocampal diffusion parameters for diagnosing Alzheimer disease pathology in mild cognitive impairment. MATERIALS AND METHODS: Sixty-nine patients with mild cognitive impairment underwent both CSF measurement and multi-shell diffusion imaging at 3T. Based on the CSF biomarker level, patients were classified according to the presence (Alzheimer disease group, n = 35) or absence (non-Alzheimer disease group, n = 34) of Alzheimer disease pathology. Neurite orientation dispersion and density imaging and diffusion tensor imaging parametric maps were generated. Two observers independently created the hippocampal region of interest for calculating histogram features. Interobserver correlations were calculated. The statistical significance of intergroup differences was tested by using the Mann-Whitney U test. Logistic regression analyses, using both the clinical scale and the image data, were used to predict intergroup differences, after which group discriminations were performed. RESULTS: Most intraclass correlation coefficient values were between 0.59 and 0.91. In the regions of interest of both observers, there were statistically significant intergroup differences for the left-side neurite orientation dispersion and density imaging-derived intracellular volume fraction, right-side diffusion tensor imaging-derived mean diffusivity, left-side diffusion tensor imaging-derived mean diffusivity, axial diffusivity, and radial diffusivity (P < .05). Logistic regression models revealed that diffusion parameters contributed the most to discriminating between the groups. The areas under the receiver operating characteristic curve for the regions of interest of observers A/B were 0.69/0.68, 0.69/0.68, 0.73/0.68, 0.71/0.68, and 0.68/0.68 for the left-side intracellular volume fraction (mean), right-side mean diffusivity (mean), left-side mean diffusivity (10th percentile), axial diffusivity (10th percentile), and radial diffusivity (mean). CONCLUSIONS: Hippocampal diffusion parameters might be useful for the early diagnosis of Alzheimer disease.

Renal dysfunction, malignant neoplasms, atherosclerotic cardiovascular diseases, and sarcopenia as key outcomes observed in a three-year follow-up study using the Werner Syndrome Registry.

Werner syndrome is an adult-onset progeria syndrome that results in various complications. This study aimed to clarify the profile and secular variation of the disease. Fifty-one patients were enrolled and registered in the Werner Syndrome Registry. Their data were collected annually following registration. A cross-sectional analysis at registration and a longitudinal analysis between the baseline and each subsequent year was performed. Pearson's chi-squared and Wilcoxon signed-rank tests were used. Malignant neoplasms were observed from the fifth decade of life (mean onset: 49.7 years) and were observed in approximately 30% of patients during the 3-year survey period. Regarding renal function, the mean estimated glomerular filtration rate calculated from serum creatinine (eGFRcre) and eGFRcys, which were calculated from cystatin C in the first year, were 98.3 and 83.2 mL/min/1.73 m2, respectively, and differed depending on the index used. In longitudinal analysis, the average eGFRcre for the first and fourth years was 74.8 and 63.4 mL/min/1.73 m2, showing a rapid decline. Secular changes in Werner syndrome in multiple patients were identified. The prevalence of malignant neoplasms is high, and renal function may decline rapidly. It is, therefore, necessary to carry out active and detailed examinations and pay attention to the type and dose of the drugs used.

Effects of luseogliflozin treatment on hyperglycemia-induced muscle atrophy in rats.

Diabetes mellitus is recognized as a risk factor for sarcopenia. Luseogliflozin, a selective sodium-glucose cotransporter 2 (SGLT2) inhibitor, reduces inflammation and oxidative stress by improving hyperglycemia, subsequently improving hepatosteatosis or kidney dysfunction. However, the effects of SGLT2 inhibitor on the regulation of skeletal muscle mass or function in hyperglycemia are still unknown. In this study, we investigated the effects of luseogliflozin-mediated attenuation of hyperglycemia on the prevention of muscle atrophy. Twenty-four male Sprague-Dawley rats were randomly divided into four groups: control, control with SGLT2 inhibitor treatment, hyperglycemia, and hyperglycemia with SGLT2 inhibitor treatment. The hyperglycemic rodent model was established using a single injection of streptozotocin, a compound with preferential toxicity toward pancreatic beta cells. Muscle atrophy in streptozotocin-induced hyperglycemic model rats was inhibited by the suppression of hyperglycemia using luseogliflozin, which consequently suppressed hyperglycemia-mediated increase in the levels of advanced glycation end products (AGEs) and activated the protein degradation pathway in muscle cells. Treatment with luseogliflozin can restore the hyperglycemia-induced loss in the muscle mass to some degree partly through the inhibition of AGEs-induced or homeostatic disruption of mitochondria-induced activation of muscle degradation.

Longitudinal association of hypertension and dyslipidemia with cognitive function in community-dwelling older adults: the SONIC study.

The associations among cognitive function, hypertension, and dyslipidemia in older adults are controversial. Therefore, we investigated the associations among cognitive decline, hypertension, dyslipidemia, and their combination in community-dwelling older people in their 70s, 80s, and 90s in the long-term observational Septuagenarians, Octogenarians, Nonagenarians, Investigation with Centenarians (SONIC) study. We administered the Montreal Cognitive Assessment Japanese version (MoCA-J) by trained geriatricians and psychologists, and conducted blood testing and blood pressure (BP) measuring by medical staff involving 1186 participants. We performed multiple regression analysis to assess the relationships among hypertension, dyslipidemia, their combination, and lipid and BP levels with cognitive function at the 3-year follow-up after adjusting for covariate factors. At the baseline, the percentage of the combination of hypertension and dyslipidemia was 46.6% (n = 553), hypertension was 25.6% (n = 304), dyslipidemia was 15.0% (n = 178), and that without hypertension or dyslipidemia was 12.7% (n = 151). Conducting multiple regression analysis, no significant correlation was found between the combination of hypertension and dyslipidemia and MoCA-J score. In the group with the combination, high high-density lipoprotein cholesterol (HDL) levels resulted in higher MoCA-J scores at the follow-up (ß = 0.06; P < 0.05) and high diastolic BP (DBP) also resulted in higher MoCA-J scores (ß = 0.08; P < 0.05). The results suggest that high HDL and DBP levels of individuals with HT & DL and high SBP levels of individuals with HT were associated with cognitive function in community-dwelling older adults. In the SONIC study, which is an epidemiological study of Japanese older persons aged 70 years or older, a disease-specific examination suggested that high HDL and DBP levels of individuals with hypertension & dyslipidemia and high SBP levels of individuals with hypertension were associated with maintaining cognitive function in community-dwelling older adults.

Antiepileptic Drugs Modulate Alzheimer-Related Tau Aggregation in a Neuronal Activity-Independent Manner.

INTRODUCTION: A rapidly increasing number of patients with dementia present a serious social problem. Recently, the incidence of epilepsy in patients with Alzheimer's disease (AD) is increasing, drawing attention to the pathological relationship between the two conditions. Clinical studies have suggested the protective action of antiepileptic agents on dementia; however, the underlying mechanism remains unknown. We evaluated the effects of multiple antiepileptic drugs using tau aggregation assay systems to determine the effects of antiepileptic agents on tau aggregation, a major neuropathological finding associated with AD. METHODS: We evaluated the effects of seven antiepileptic agents on intracellular tau aggregation using a tau-biosensor cell-based high-throughput assay. Next, we tested these agents in a cell-free tau aggregation assay using thioflavin T (ThT). RESULTS: The assay results revealed that phenobarbital inhibited tau aggregation, whereas sodium valproate, gabapentin, and piracetam promoted tau aggregation. In the cell-free tau aggregation assay using ThT, we confirmed that phenobarbital significantly inhibited tau aggregation. CONCLUSION: Antiepileptic drugs may modify the tau pathology in AD in a neural activity-independent manner. Our finding may provide an important insight into the optimization of antiepileptic drug therapy in older adults with dementia.

Lower cognitive function as a risk factor for anemia among older Japanese women from the longitudinal observation in the SONIC study.

AIM: The aging-related increase in the incidence of anemia potentially affects the mortality risk. Lower cognitive function is common among older adults, and anemia is one of the causes of cognitive decline. However, to the best of our knowledge, no study has investigated whether cognitive decline is a risk factor for anemia in older people. Therefore, in this study, we used a 3-year longitudinal evaluation to examine the association of cognitive function with anemia in community-dwelling older adults. METHODS: This longitudinal study enrolled participants without anemia (diagnosed based on the World Health Organization's criteria) at baseline. Cognitive function was assessed using the Japanese version of the Montreal Cognitive Assessment. Multiple logistic regression models were used to examine the association between cognitive function at baseline and the presence of anemia 3 years later. RESULTS: Participants were in the 69-71 and 79-81 years age groups, and 974 older people (48.6% men) were enrolled, of whom 126 (12.9%) had anemia after 3 years. After adjusting, cognitive function at baseline was associated with anemia in women, but not in men. CONCLUSIONS: Older Japanese women with lower cognitive function have an increased risk for anemia 3 years later. The adoption of a lifestyle that utilizes or improves cognitive function might be important to prevent anemia in older women. Geriatr Gerontol Int 2023; 23: 334-340.

Novel pathophysiological roles of α-synuclein in age-related vascular endothelial dysfunction.

Although α-synuclein (SNCA) is a well-known pathological molecule involved in synucleinopathy in neurons, its physiological roles remain largely unknown. We reported that serum SNCA levels have a close inverse correlation with blood pressure and age, which indicates the involvement of SNCA in age-related endothelial dysfunction. Therefore, this study aimed to elucidate the molecular functions of SNCA in the endothelium. We confirmed that SNCA was expressed in and secreted from endothelial cells (ECs). Exogenous treatment with recombinant SNCA (rSNCA) activated the Akt-eNOS axis and increased nitric oxide production in ECs. Treatment with rSNCA also suppressed TNF-α- and palmitic acid-induced NF-κB activation, leading to the suppression of VCAM-1 upregulation and restoration of eNOS downregulation in ECs. As for endogenous SNCA expression, replicative senescence resulted in the attenuation of SNCA expression in cultured ECs, similar to the effects of physiological aging on mice aortas. The siRNA-mediated silencing of SNCA consistently resulted in senescent phenotypes, such as eNOS downregulation, increased ß-gal activity, decreased Sirt1 expression, and increased p53 expression, in ECs. Ex vivo assessment of endothelial functions using aortic rings revealed impaired endothelium-dependent acetylcholine-induced relaxation in SNCA knockout (KO) mice. Furthermore, SNCA KO mice, especially those on a high-fat diet, displayed elevated blood pressure compared with wild-type mice; this could be eNOS dysfunction-dependent because of the lower difference caused by L-NAME administration. These results indicate that exogenous and endogenous SNCA in ECs might physiologically maintain vascular integrity, and age-related endothelial dysfunction might be partially ascribed to loss-of-function of SNCA in ECs.

Self-Monitoring Home Blood Pressure in Community-Dwelling Older People: Age Differences in White-Coat and Masked Phenomena and Related Factors-The SONIC Study.

Some studies reported that home blood pressure (HBP) monitoring was conducted by community-dwelling older people themselves, but there have been few studies on HBP including very old populations aged over 90 years old. Thus, the aim of the present study was to clarify the current situation of white-coat and masked phenomena defined by on-site and home BP measurements in community-dwelling old and oldest-old populations. The study subjects were 380 participants from the SONIC study, a cohort study of a community-dwelling old population, who measured their HBP in a series of 3-5 days by themselves and brought their HBP records to the venue on the survey day. Study participants' characteristics were as follows: female, 185 (48.7%); male, 195 (51.3%); 70s, 95 (25.0%); 80s, 245 (64.5%); and 90s, 40 (10.5%). A total of 344 (90.5%) participants had hypertension. A total of 291 (76.6%) hypertensive participants taking antihypertensive medication were analyzed in the present study. Regarding the types of hypertension defined by home and on-site BP, they showed white-coat phenomenon, 183 (48.2%); masked phenomenon, 115 (30.3%); sustained hypertension, 130 (34.2%); and normotension, 82 (21.6%). On comparison of age groups, there was a tendency for the white-coat phenomenon to be common in young-old people in their 70s and the masked phenomenon to be common in very old people in their 90s. Therefore, since the detection of white-coat and masked phenomena is closely associated with appropriate BP management, it is very important for community-dwelling older populations to self-monitor HBP.

A novel chronic dural port platform for continuous collection of cerebrospinal fluid and intrathecal drug delivery in free-moving mice.

BACKGROUND: Cerebrospinal fluid (CSF) provides a close representation of pathophysiological changes occurring in the central nervous system (CNS); therefore, it has been employed in pathogenesis research and biomarker development for CNS disorders. CSF obtained from valid mouse models relevant to CNS disorders can be an important resource for successful biomarker and drug development. However, the limited volume of CSF that can be collected from tiny intrathecal spaces and the technical difficulties involved in CSF sampling has been a bottleneck that has hindered the detailed analysis of CSF in mouse models. METHODS: We developed a novel chronic dural port (CDP) method without cannulation for CSF collection of mice. This method enables easy and repeated access to the intrathecal space in a free-moving, unanesthetized mouse, thereby enabling continuous long-term CSF collection with minimal tissue damage and providing a large volume of high-quality CSF from a single mouse. When combined with chemical biosensors, the CDP method allows for real-time monitoring of the dynamic changes in neurochemicals in the CSF at a one-second temporal resolution in free-moving mice. Moreover, the CDP can serve as a direct access point for the intrathecal injection of CSF tracers and drugs. RESULTS: We established a CDP implantation and continuous CSF collection protocol. The CSF collected using CDP was not contaminated with blood and maintained physiological concentrations of basic electrolytes and proteins. The CDP method did not affect mouse's physiological behavior or induce tissue damage, thereby enabling a stable CSF collection for up to four weeks. The spatio-temporal distribution of CSF tracers delivered using CDP revealed that CSF metabolism in different brain areas is dynamic. The direct intrathecal delivery of centrally acting drugs using CDP enabled real-time behavioral assessments in free-moving mice. CONCLUSIONS: The CDP method enables the collection of a large volume of high-quality CSF and direct intrathecal drug administration with real-time behavioral assessment in free-moving mice. Combined with animal models relevant to CNS disorders, this method provides a unique and valuable platform for biomarker and therapeutic drug research.

Alcohol drinking patterns have a positive association with cognitive function among older people: a cross-sectional study.

BACKGROUND: The relationship between moderate alcohol drinking or other alcohol drinking patterns such as frequency, beverage type, and situation of drinking and cognitive function is not sufficiently clear in older people. The purpose of this study was to investigate the association between alcohol drinking patterns and cognitive function in community-dwelling Japanese people aged 75 and over. METHODS: This study was a cross-sectional design based on a prospective cohort study called the SONIC study. Subjects were older people aged 75-77 or 85-87 who voluntarily participated in 2016-2017. Drinking information was collected for daily drinking frequency, daily drinking intake, beverage type, and non-daily drinking opportunity. Cognitive function was measured using the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Other potential confounding factors evaluated were age, sex, medical factors, and psychosocial factors. An analysis of covariance was performed to evaluate the MoCA-J score relative to drinking frequency or alcohol intake. Multiple regression analysis was performed to investigate the association between beverage type or non-daily drinking opportunity and the MoCA-J score. RESULTS: The final number of participants analyzed was 1,226. The MoCA-J score for participants who reported drinking alcohol 1-6 days/week was significantly higher than that for those who reported drinking none or every day. No significant difference in the MoCA-J score was observed relative to daily alcohol intake. In terms of beverage type, wine was associated positively with the MoCA-J score. Non-daily drinking opportunity was also associated positively with the MoCA-J score. CONCLUSIONS: Moderate-frequency drinking, wine consumption, and non-daily drinking opportunities were associated with higher cognitive function in community-dwelling Japanese aged 75 and over. Further longitudinal studies are needed to clarify the causal relationships.

Clinical characteristics of older adults with hypertension and unrecognized cognitive impairment.

To treat older patients with hypertension, it is important to detect cognitive impairment at an early stage because of its potential influence on treatment efficacy and functional prognosis. In this study, we aimed to identify the incidence and determinants of cognitive impairment in hypertensive patients aged 65 years and above who visited our outpatient clinic and were not previously diagnosed with cognitive impairment. Among 312 patients with hypertension, we found that 35% (n = 109) and 7.7% (n = 24) had cognitive impairment and dementia, respectively, as defined by the Mini-Mental State Examination (≤27 or ≤23, respectively). Patients with cognitive impairment were older, had lower levels of education, and had lower instrumental activities of daily living (IADL) scores than those without cognitive impairment. Multiple regression analysis revealed that age and IADL were associated with cognitive impairment in patients with hypertension. Regarding the treatment of hypertension, the office and home blood pressure levels, number of antihypertensive medications prescribed, and proportion of the use of each antihypertensive drug was equivalent between patients with and without cognitive impairment. Finally, patients with unrecognized cognitive impairment showed distinct clinical characteristics, including high antihypertensive medication burden and preserved IADL, when compared to hypertensive patients in the different cohorts of definitive mild cognitive impairment of a similar age. These findings suggest that older hypertensive patients are at a high risk of masked cognitive decline, even if they are functionally independent.

Association between protein intake and changes in renal function among Japanese community-dwelling older people: The SONIC study.

AIM: The aim of this study was to clarify the association between dietary protein intake and decline in the estimated glomerular filtration rate (eGFR) among Japanese older adults. METHODS: We used the data of the Septuagenarians, Octogenarians and Nonagenarians Investigation with Centenarians (SONIC) study, an ongoing narrow-age range cohort study: 69-71 years, 79-81 years and 89-91 years. The outcome variable, change in eGFR, was estimated from serum creatinine measured at the baseline and 3-year follow up, and the exposure variable, protein intake, was calculated using the brief-type self-administered diet history questionnaire at the baseline. Associations between eGFR change and protein intake were determined by multiple linear regression analysis. RESULTS: The mean eGFR change per year was -1.89 mL/min/1.73 m2 . The mean protein intake was 1.50 g/kg/day. The results of this study showed that there was no significant association between protein or animal protein intake and change in eGFR per year in the entire population of participants, including the very elderly, but there was a significant positive association in those whose renal function fell into chronic kidney disease stage G3 or G4. CONCLUSIONS: Protein intake among community-dwelling older adults was not associated with lower eGFR, and for older chronic kidney disease patients, protein and animal protein intakes were more beneficial in maintaining eGFR. The results provide evidence that protein intake should not be restricted for older patients with chronic kidney disease, including the very elderly. Geriatr Gerontol Int 2022; 22: 286-291.

Interleukin-15 receptor subunit alpha regulates interleukin-15 localization and protein expression in skeletal muscle cells.

NEW FINDINGS: What is the central question of this study? How are the dynamics of interleukin (IL)-15 and its receptors altered during the differentiation of myoblasts into myotubes, and how is IL-15 regulated? What is the main finding and its importance? The mRNA levels of IL-15 and interleukin-2 receptor subunits beta and gamma increase during skeletal muscle differentiation, whereas interleukin-15 receptor subunit alpha (IL-15RA) exhibits different kinetics. IL-15RA regulates the localization and expression of IL-15 at the protein level. ABSTRACT: Interleukin-15 (IL-15) is a myokine in the interleukin-2 (IL-2) family that is generated in the skeletal muscle during exercise. The functional effect of IL-15 involves muscle regeneration and metabolic regulation in skeletal muscle. Reports have indicated that interleukin-15 receptor subunit alpha (IL-15RA) acts by regulating IL-15 localization in immune cells. However, the dynamics of IL-15 and its receptors, which regulate the IL-15 pathway in skeletal muscle differentiation, have not yet been clarified. In this study, we investigated the mechanism of IL-15 regulation using a mouse skeletal muscle cell line, C2C12 cells. We found that the mRNA expression of IL-15, interleukin-2 receptor subunit beta (IL-2RB; CD122) and interleukin-2 receptor subunit gamma (IL-2RG; CD132) increased, but that IL-15RA exhibited different kinetics as differentiation progressed. We also found that IL-15, mainly present in the cytosol, pre-assembled with IL-15RA in the cytosol and fused to the plasma membrane. Moreover, IL-15RA increased IL-15 protein levels. Our findings suggest that genes involved in the IL-15 signalling complex are enhanced with the differentiation of myotubes and that IL-15RA regulates the protein kinetics of IL-15 signalling in skeletal muscle.

The Association Between Longevity-Associated FOXO3 Allele and Heart Disease in Septuagenarians and Octogenarians: The SONIC Study.

The G allele of FOXO3 gene (single-nucleotide polymorphism; rs2802292) is strongly associated with human longevity. However, knowledge of the effect of FOXO3 in older populations, men or women, with heart disease is limited. This cross-sectional study in Japan included 1836 older adults in the 70- and 80-year-old groups. DNA samples isolated from buffy coat samples of peripheral blood were used to genotype FOXO3 (rs2802292). Self-reports were used to obtain heart disease data according to physician diagnosis. Multiple logistic regression was used to test the association by adjusting for the traditional risk factor of heart disease. The prevalence of heart disease in women FOXO3 G-allele carriers was higher than noncarriers (16.7% vs 11.6%, p = .022). The prevalence of coronary heart disease was lower for FOXO3 G carriers in the 70-year-old group for both sexes (men: 9.3% vs 4.3%, p = .042 and women: 10% vs 9%, p = .079, respectively). The G allele was negatively associated with heart disease after adjusting for diabetes, hypertension, dyslipidemia, and smoking in men (odds ratio [OR] = 0.70, 95% confidence intervals [CIs], 0.49-0.99, p = .046), although the association was weaker after full adjustment. In contrast, women carriers of the FOXO3 G allele showed a positive association with heart disease after total adjustment (OR = 1.49, 95% CI, 1.00-2.21, p = .049). In conclusion, the longevity-associated G allele of FOXO3 was observed to have contrasting associations with heart disease prevalence according to sex in older Japanese. To further confirm this association, a longitudinal study and a large sample size will be required.

Periodontal inflamed surface area is associated with hs-CRP in septuagenarian Japanese adults in cross-sectional findings from the SONIC study.

Periodontal disease is a chronic inflammatory condition that affects various peripheral organs. The periodontal inflamed surface area (PISA) quantifies periodontitis severity and the spread of inflammatory wounds. This study aimed to investigate the association between PISA and high-sensitivity C-reactive protein (hs-CRP), a systemic inflammation marker. This study included 250 community-dwelling septuagenarians (69-71 years). We collected information on their medical (e.g., diabetes and dyslipidemia) and dental examinations (e.g., measurement of the probing pocket depth). Generalized linear model analysis was used to explore the association between PISA and hs-CRP levels. There was a significant difference in hs-CRP levels between groups with PISA ≥ 500 and < 500 (p = 0.017). Moreover, the generalized linear model analysis revealed a significant association between PISA and hs-CRP levels (risk ratio = 1.77; p = 0.033) even after adjusting other factors. Further, we found a correlation between PISA and hs-CRP (Spearman's rank correlation coefficient, rs = 0.181; p = 0.023). Our findings suggest that PISA is an effective index for estimating the effect of periodontitis on the whole body, enabling medical-dental cooperation.

Double Deletion of Angiotensin II Type 2 and Mas Receptors Accelerates Aging-Related Muscle Weakness in Male Mice.

Background The activation of AT2 (angiotensin II type 2 receptor ) and Mas receptor by angiotensin II and angiotensin-(1-7), respectively, is the primary process that counteracts activation of the canonical renin-angiotensin system (RAS). Although inhibition of canonical RAS could delay the progression of physiological aging, we recently reported that deletion of Mas had no impact on the aging process in mice. Here, we used male mice with a deletion of only AT2 or a double deletion of AT2 and Mas to clarify whether these receptors contribute to the aging process in a complementary manner, primarily by focusing on aging-related muscle weakness. Methods and Results Serial changes in grip strength of these mice up to 24 months of age showed that AT2/Mas knockout mice, but not AT2 knockout mice, had significantly weaker grip strength than wild-type mice from the age of 18 months. AT2/Mas knockout mice exhibited larger sizes, but smaller numbers and increased frequency of central nucleation (a marker of aged muscle) of single skeletal muscle fibers than AT2 knockout mice. Canonical RAS-associated genes, inflammation-associated genes, and senescence-associated genes were highly expressed in skeletal muscles of AT2/Mas knockout mice. Muscle angiotensin II content increased in AT2/Mas knockout mice. Conclusions Double deletion of AT2 and Mas in mice exaggerated aging-associated muscle weakness, accompanied by signatures of activated RAS, inflammation, and aging in skeletal muscles. Because aging-associated phenotypes were absent in single deletions of the receptors, AT2 and Mas could complement each other in preventing local activation of RAS during aging.

RAGE ligands stimulate angiotensin II type I receptor (AT1) via RAGE/AT1 complex on the cell membrane.

The receptor for advanced glycation end-products (RAGE) and the G protein-coupled angiotensin II (AngII) type I receptor (AT1) play a central role in cardiovascular diseases. It was recently reported that RAGE modifies AngII-mediated AT1 activation via the membrane oligomeric complex of the two receptors. In this study, we investigated the presence of the different directional crosstalk in this phenomenon, that is, the RAGE/AT1 complex plays a role in the signal transduction pathway of RAGE ligands. We generated Chinese hamster ovary (CHO) cells stably expressing RAGE and AT1, mutated AT1, or AT2 receptor. The activation of two types of G protein α-subunit, Gq and Gi, was estimated through the accumulation of inositol monophosphate and the inhibition of forskolin-induced cAMP production, respectively. Rat kidney epithelial cells were used to assess RAGE ligand-induced cellular responses. We determined that RAGE ligands activated Gi, but not Gq, only in cells expressing RAGE and wildtype AT1. The activation was inhibited by an AT1 blocker (ARB) as well as a RAGE inhibitor. ARBs inhibited RAGE ligand-induced ERK phosphorylation, NF-κB activation, and epithelial-mesenchymal transition of rat renal epithelial cells. Our findings suggest that the activation of AT1 plays a central role in RAGE-mediated cellular responses and elucidate the role of a novel molecular mechanism in the development of cardiovascular diseases.

Association between physical function and onset of coronary heart disease in a cohort of community-dwelling older populations: The SONIC study.

BACKGROUND: Physical function is a strong predictor of the adverse outcomes of cardiovascular disease in older populations. However, studies of healthy older people on the prevention of coronary heart disease (CHD) are very limited. OBJECTIVES: We prospectively examined the association of walking speed and handgrip strength with CHD in the community-dwelling older populations. METHODS: The study cohort in Japan included 1272 older people free from heart disease at the baseline. Physical function was identified based on walking speed and handgrip strength assessment at the survey site. Any new case of CHD was identified based on a self-reported doctor's diagnosis. Cox-proportion hazard models were adjusted for covariate factors to examine the CHD risk. RESULTS: During the 7-year follow-up, 45 new cases of CHD (25 men and 20 women) were documented. Slow walking speed was strongly associated with CHD risk after adjusting for all confounding factors in the total participants and women (hazard ratio (HR)= 2.53, 95%confidence interval (CI), 1.20-5.33, p=0.015, and HR= 4.78, 95% CI,1.07-21.35, p=0.040, respectively), but not in men. Weak grip strength was associated with CHD after age-adjustment (HR= 2.45, 95%CI, 1.03-5.81, p=0.043) only in men. However, after additional multivariate adjustment, the associations were getting weaker.

The endocytosis of oxidized LDL via the activation of the angiotensin II type 1 receptor.

Arrestin-dependent activation of a G-protein-coupled receptor (GPCR) triggers endocytotic internalization of the receptor complex. We analyzed the interaction between the pattern recognition receptor (PRR) lectin-like oxidized low-density lipoprotein (oxLDL) receptor (LOX-1) and the GPCR angiotensin II type 1 receptor (AT1) to report a hitherto unidentified mechanism whereby internalization of the GPCR mediates cellular endocytosis of the PRR ligand. Using genetically modified Chinese hamster ovary cells, we found that oxLDL activates Gαi but not the Gαq pathway of AT1 in the presence of LOX-1. Endocytosis of the oxLDL-LOX-1 complex through the AT1-ß-arrestin pathway was demonstrated by real-time imaging of the membrane dynamics of LOX-1 and visualization of endocytosis of oxLDL. Finally, this endocytotic pathway involving GPCR kinases (GRKs), ß-arrestin, and clathrin is relevant in accumulating oxLDL in human vascular endothelial cells. Together, our findings indicate that oxLDL activates selective G proteins and ß-arrestin-dependent internalization of AT1, whereby the oxLDL-LOX-1 complex undergoes endocytosis.