Pub Date : 2024-08-23DOI: 10.1152/ajpheart.00240.2024
Ida Maiorov, Konstantin Bagrov, Roy Efraim, Galit Ankri Eliyahu, Amit Livneh, Amir Landesberg
Background: Septic cardiomyopathy (SCM) with diastolic dysfunction carries a poor prognosis, and the mechanisms underlying the development of diastolic dysfunction remain unclear. Matrix metalloproteinase-8 (MMP-8) is released from neutrophils and degrades collagen I. MMP-8 levels correlate with SCM severity.
Objectives: We scrutinized, for the first time, the direct impact of MMP-8 on cardiac systolic and diastolic functions.
Methods: Isolated rat hearts were perfused with Krebs-Henseleit solution in a Langendorff setup with computer-controlled filling pressures of both ventricles at isovolumetric regime. The end-diastolic pressure (EDP) varied periodically between 3 and 20 mmHg. After baseline recordings, MMP-8 (100 µg/ml) was added to the perfusion. Short-axis views of both ventricles were continuously acquired by echocardiography.
Results: MMP-8 perfusion resulted in progressive decline in peak systolic pressures (Psys) in both ventricles, but without significant changes in their end-systolic pressure-area relationships (ESPARs). Counterintuitively, conspicuous leftward shifts of the end-diastolic pressure-area relationships (EDPARs) were observed in both ventricles. The LV end-diastolic area (EDA) decreased by 32.8±5.7%, (p=0.008), at EDP of 10.5±0.4 mmHg, when LV Psys dropped by 20%. The decline of Psys was primarily due to the decrease in EDA and restoring the baseline EDA by increasing EDP recovered 81.33 ± 5.87% of the pressure drops.
Conclusion: Collagen I generates tensile (eccentric) stress, and its degradation by MMP-8 causes EDPVR leftward shift, resulting in diastolic and systolic dysfunctions. The diastolic dysfunction explains the clinically observed fluid unresponsiveness, while the decrease in EDV diminishes the systolic functions. MMP-8 can explain the development of SCM with diastolic dysfunction.
{"title":"MMP-8 causes leftward shift in end-diastolic pressure-volume relationship and may explain the development of diastolic dysfunction in septic cardiomyopathy.","authors":"Ida Maiorov, Konstantin Bagrov, Roy Efraim, Galit Ankri Eliyahu, Amit Livneh, Amir Landesberg","doi":"10.1152/ajpheart.00240.2024","DOIUrl":"https://doi.org/10.1152/ajpheart.00240.2024","url":null,"abstract":"<p><strong>Background: </strong>Septic cardiomyopathy (SCM) with diastolic dysfunction carries a poor prognosis, and the mechanisms underlying the development of diastolic dysfunction remain unclear. Matrix metalloproteinase-8 (MMP-8) is released from neutrophils and degrades collagen I. MMP-8 levels correlate with SCM severity.</p><p><strong>Objectives: </strong>We scrutinized, for the first time, the direct impact of MMP-8 on cardiac systolic and diastolic functions.</p><p><strong>Methods: </strong>Isolated rat hearts were perfused with Krebs-Henseleit solution in a Langendorff setup with computer-controlled filling pressures of both ventricles at isovolumetric regime. The end-diastolic pressure (EDP) varied periodically between 3 and 20 mmHg. After baseline recordings, MMP-8 (100 µg/ml) was added to the perfusion. Short-axis views of both ventricles were continuously acquired by echocardiography.</p><p><strong>Results: </strong>MMP-8 perfusion resulted in progressive decline in peak systolic pressures (Psys) in both ventricles, but without significant changes in their end-systolic pressure-area relationships (ESPARs). Counterintuitively, conspicuous leftward shifts of the end-diastolic pressure-area relationships (EDPARs) were observed in both ventricles. The LV end-diastolic area (EDA) decreased by 32.8±5.7%, (p=0.008), at EDP of 10.5±0.4 mmHg, when LV Psys dropped by 20%. The decline of Psys was primarily due to the decrease in EDA and restoring the baseline EDA by increasing EDP recovered 81.33 ± 5.87% of the pressure drops.</p><p><strong>Conclusion: </strong>Collagen I generates tensile (eccentric) stress, and its degradation by MMP-8 causes EDPVR leftward shift, resulting in diastolic and systolic dysfunctions. The diastolic dysfunction explains the clinically observed fluid unresponsiveness, while the decrease in EDV diminishes the systolic functions. MMP-8 can explain the development of SCM with diastolic dysfunction.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142034976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-16DOI: 10.1152/ajpheart.00557.2024
Tatum M Weishaar, Beth A Habecker
{"title":"Activation of IP3R in atrial cardiomyocytes leads to generation of cytosolic cAMP.","authors":"Tatum M Weishaar, Beth A Habecker","doi":"10.1152/ajpheart.00557.2024","DOIUrl":"https://doi.org/10.1152/ajpheart.00557.2024","url":null,"abstract":"","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141987292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-09DOI: 10.1152/ajpheart.00702.2023
Aida Rahimi Kahmini, Isela C Valera, Rhiannon Q Crawford, Luaye Samarah, Gisienne Reis, Salma Elsheikh, Rosemeire M Kanashiro-Takeuchi, Nazanin Mohammadipoor, Bolade S Olateju, Aaron R Matthews, Michelle S Parvatiyar
Numerous genes including sarcospan (SSPN) have been designated as obesity-susceptibility genes by human genome-wide association studies. Variants in the SSPN locus have been linked with sex-dependent obesity-associated traits, however this association has not been investigated in vivo. To delineate the role SSPN plays in regulating metabolism with potential to impact cardiac function we subjected young and aged global SSPN-deficient (SSPN-/-) male and female mice to obesogenic conditions (60% fat diet). We hypothesized that loss of SSPN combined with metabolic stress would increase susceptibility of mice to cardiometabolic disease. Baseline and endpoint assessments of several anthropometric parameters were performed including weight, glucose tolerance, and fat distribution of mice fed control (CD) and high fat diet (HFD). Doppler echocardiography was used to monitor cardiac function. White adipose and cardiac tissues were assessed for inflammation utilizing histological, gene expression and cytokine analysis. Overall, SSPN deficiency protected both sexes and ages from diet-induced obesity with a greater effect in females. While SSPN-/- HFD mice gained less weight than WT cohorts, SSPN-/- CD groups increased weight. Furthermore, aged SSPN-/- mice developed glucose intolerance regardless of diet. Echocardiography showed preserved systolic function for all groups, however aged SSPN-/- males (CD) exhibited significant increases in LVmass and (HFD) signs of diastolic dysfunction. Cytokine analysis revealed significantly increased IL-1α and IL-17A in white adipose tissue from young SSPN-/- male mice that may be protective from diet-induced obesity. Overall, these studies suggest several sex-dependent mechanisms influence the role SSPN plays in metabolic responses that become evident with age.
{"title":"Aging Reveals a Sex-Dependent Susceptibility of Sarcospan-Deficient Mice to Cardiometabolic Disease.","authors":"Aida Rahimi Kahmini, Isela C Valera, Rhiannon Q Crawford, Luaye Samarah, Gisienne Reis, Salma Elsheikh, Rosemeire M Kanashiro-Takeuchi, Nazanin Mohammadipoor, Bolade S Olateju, Aaron R Matthews, Michelle S Parvatiyar","doi":"10.1152/ajpheart.00702.2023","DOIUrl":"https://doi.org/10.1152/ajpheart.00702.2023","url":null,"abstract":"<p><p>Numerous genes including sarcospan (SSPN) have been designated as obesity-susceptibility genes by human genome-wide association studies. Variants in the <i>SSPN</i> locus have been linked with sex-dependent obesity-associated traits, however this association has not been investigated in vivo. To delineate the role SSPN plays in regulating metabolism with potential to impact cardiac function we subjected young and aged global SSPN-deficient (SSPN<sup>-/-</sup>) male and female mice to obesogenic conditions (60% fat diet). We hypothesized that loss of SSPN combined with metabolic stress would increase susceptibility of mice to cardiometabolic disease. Baseline and endpoint assessments of several anthropometric parameters were performed including weight, glucose tolerance, and fat distribution of mice fed control (CD) and high fat diet (HFD). Doppler echocardiography was used to monitor cardiac function. White adipose and cardiac tissues were assessed for inflammation utilizing histological, gene expression and cytokine analysis. Overall, SSPN deficiency protected both sexes and ages from diet-induced obesity with a greater effect in females. While SSPN<sup>-/-</sup> HFD mice gained less weight than WT cohorts, SSPN<sup>-/-</sup> CD groups increased weight. Furthermore, aged SSPN<sup>-/-</sup> mice developed glucose intolerance regardless of diet. Echocardiography showed preserved systolic function for all groups, however aged SSPN<sup>-/-</sup> males (CD) exhibited significant increases in LVmass and (HFD) signs of diastolic dysfunction. Cytokine analysis revealed significantly increased IL-1α and IL-17A in white adipose tissue from young SSPN<sup>-/-</sup> male mice that may be protective from diet-induced obesity. Overall, these studies suggest several sex-dependent mechanisms influence the role SSPN plays in metabolic responses that become evident with age.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141905579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-14DOI: 10.1152/ajpheart.00665.2023
Majd AlGhatrif, Christopher H Morrell, Jerome L Fleg, Paul D Chantler, Samer S Najjar, Lewis C Becker, Luigi Ferrucci, Gary Gerstenblith, Edward G Lakatta
Aging is associated with a significant decline in aerobic capacity assessed by maximal exercise oxygen consumption (V̇o2max). The relative contributions of the specific V̇o2 components driving this decline, namely cardiac output (CO) and arteriovenous oxygen difference (A - V)O2, remain unclear. We examined this issue by analyzing data from 99 community-dwelling participants (baseline age: 21-96 yr old; average follow-up: 12.6 yr old) from the Baltimore Longitudinal Study of Aging, free of clinical cardiovascular disease. V̇o2peak, a surrogate of V̇o2max, was used to assess aerobic capacity during upright cycle ergometry. Peak exercise left ventricular volumes, heart rate, and CO were estimated using repeated gated cardiac blood pool scans. The Fick equation was used to calculate (A - V)O2diff,peak from COpeak and V̇o2peak. In unadjusted models, V̇o2peak, (A - V)O2diff,peak, and COpeak declined longitudinally over time at steady rates with advancing age. In multiple linear regression models adjusting for baseline values and peak workload, however, steeper declines in V̇o2peak and (A - V)O2diff,peak were observed with advanced entry age but not in COpeak. The association between the declines in V̇o2peak and (A - V)O2diff,peak was stronger among those ≥50 yr old compared with their younger counterparts, but the difference between the two age groups did not reach statistical significance. These findings suggest that age-associated impairment of peripheral oxygen utilization during maximal exercise poses a stronger limitation on peak V̇o2 than that of CO. Future studies examining interventions targeting the structure and function of peripheral muscles and their vasculature to mitigate age-associated declines in (A - V)O2diff are warranted.NEW & NOTEWORTHY The age-associated decline in aerobic exercise performance over an average of 13 yr in community-dwelling healthy individuals is more closely associated with decreased peripheral oxygen utilization rather than decreased cardiac output. This association was more evident in older than younger individuals. These findings suggest that future studies with larger samples examine whether these associations vary across the age range and whether the decline in cardiac output plays a greater role earlier in life. In addition, studies focused on determinants of peripheral oxygen uptake by exercising muscle may guide the selection of preventive strategies designed to maintain physical fitness with advancing age.
根据最大运动耗氧量(VO2-max)评估,衰老与运动能力的显著下降有关。导致这一下降的最大运动氧耗量的具体成分,即心输出量(CO)和动静脉氧差(A-V)O2,仍不清楚。我们通过分析来自巴尔的摩老龄化纵向研究(Baltimore Longitudinal Study of Aging)的 99 名无临床心血管疾病的社区居民(基线年龄为 21-96 岁,平均随访 12.6 年)的数据,对这一问题进行了研究。VO2-峰值是VO2-最大值的代用指标,用于评估直立循环运动中的有氧能力。运动时左心室(LV)容积峰值、心率和心输出量是通过重复门控心血池扫描估算的。菲克方程用于根据 CO 峰值和 VO2 峰值计算 (A-V) O2-峰值。在未经调整的模型中,VO2-峰值、(A-V)O2-峰值和 CO-峰值随着年龄的增长以稳定的速率纵向下降。然而,在根据基线值和峰值工作量进行调整的多元线性回归模型中,观察到 VO2 峰值和(A-V)O2 峰值随着入选年龄的增加而急剧下降,但 CO 峰值却没有。VO2-peak 和(A-V)O2-peak 下降之间的联系在年龄大于等于 50 岁的人群中比年轻人更强,但两个年龄组之间的差异未达到统计学意义。这些研究结果表明,在最大运动量时,与年龄相关的外周氧利用障碍对峰值 VO2 的限制比 CO 的限制更大。今后有必要开展研究,针对外周肌肉及其血管的结构和功能采取干预措施,以缓解与年龄相关的(A-V)氧饱和度下降。
{"title":"Longitudinal decline in peak V̇o<sub>2</sub> with aging in a healthy population is associated with a reduction in peripheral oxygen utilization but not in cardiac output.","authors":"Majd AlGhatrif, Christopher H Morrell, Jerome L Fleg, Paul D Chantler, Samer S Najjar, Lewis C Becker, Luigi Ferrucci, Gary Gerstenblith, Edward G Lakatta","doi":"10.1152/ajpheart.00665.2023","DOIUrl":"10.1152/ajpheart.00665.2023","url":null,"abstract":"<p><p>Aging is associated with a significant decline in aerobic capacity assessed by maximal exercise oxygen consumption (V̇o<sub>2max</sub>). The relative contributions of the specific V̇o<sub>2</sub> components driving this decline, namely cardiac output (CO) and arteriovenous oxygen difference (A - V)O<sub>2</sub>, remain unclear. We examined this issue by analyzing data from 99 community-dwelling participants (baseline age: 21-96 yr old; average follow-up: 12.6 yr old) from the Baltimore Longitudinal Study of Aging, free of clinical cardiovascular disease. V̇o<sub>2peak</sub>, a surrogate of V̇o<sub>2max</sub>, was used to assess aerobic capacity during upright cycle ergometry. Peak exercise left ventricular volumes, heart rate, and CO were estimated using repeated gated cardiac blood pool scans. The Fick equation was used to calculate (A - V)O<sub>2</sub><sub>diff,peak</sub> from CO<sub>peak</sub> and V̇o<sub>2peak</sub>. In unadjusted models, V̇o<sub>2peak</sub>, (A - V)O<sub>2</sub><sub>diff,peak</sub>, and CO<sub>peak</sub> declined longitudinally over time at steady rates with advancing age. In multiple linear regression models adjusting for baseline values and peak workload, however, steeper declines in V̇o<sub>2peak</sub> and (A - V)O<sub>2</sub><sub>diff,peak</sub> were observed with advanced entry age but not in CO<sub>peak</sub>. The association between the declines in V̇o<sub>2peak</sub> and (A - V)O<sub>2</sub><sub>diff,peak</sub> was stronger among those ≥50 yr old compared with their younger counterparts, but the difference between the two age groups did not reach statistical significance. These findings suggest that age-associated impairment of peripheral oxygen utilization during maximal exercise poses a stronger limitation on peak V̇o<sub>2</sub> than that of CO. Future studies examining interventions targeting the structure and function of peripheral muscles and their vasculature to mitigate age-associated declines in (A - V)O<sub>2</sub><sub>diff</sub> are warranted.<b>NEW & NOTEWORTHY</b> The age-associated decline in aerobic exercise performance over an average of 13 yr in community-dwelling healthy individuals is more closely associated with decreased peripheral oxygen utilization rather than decreased cardiac output. This association was more evident in older than younger individuals. These findings suggest that future studies with larger samples examine whether these associations vary across the age range and whether the decline in cardiac output plays a greater role earlier in life. In addition, studies focused on determinants of peripheral oxygen uptake by exercising muscle may guide the selection of preventive strategies designed to maintain physical fitness with advancing age.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11442097/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141316583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-21DOI: 10.1152/ajpheart.00162.2024
Anna Dikalova, Mingfang Ao, Liliya Tkachuk, Sergey Dikalov
Almost one-half of adults have hypertension, and blood pressure is poorly controlled in a third of patients despite the use of multiple drugs, likely because of mechanisms that are not affected by current treatments. Hypertension is linked to oxidative stress; however, common antioxidants are ineffective. Hypertension is associated with inactivation of key intrinsic mitochondrial antioxidant, superoxide dismutase 2 (SOD2), due to hyperacetylation, but the role of specific SOD2 lysine residues has not been defined. Hypertension is associated with SOD2 acetylation at lysine 68, and we suggested that deacetylation mimetic mutation of K68 to arginine in SOD2 inhibits vascular oxidative stress and attenuates hypertension. To test this hypothesis, we have developed a new deacetylation mimetic SOD2-K68R mice. We performed in vivo studies in SOD2-K68R mice using angiotensin II (ANG II) model of vascular dysfunction and hypertension. ANG II infusion in wild-type mice induced vascular inflammation and oxidative stress and increased blood pressure to 160 mmHg. SOD2-K68R mutation completely prevented increase in mitochondrial superoxide, abrogated vascular oxidative stress, preserved endothelial nitric oxide production, protected vasorelaxation, and attenuated ANG II-induced hypertension. ANG II and cytokines contribute to vascular oxidative stress and hypertension. Treatment of wild-type aortas with ANG II and cytokines in organoid culture increased mitochondrial superoxide twofold, which was completely prevented in aortas isolated from SOD2-K68R mice. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and pathogenesis of hypertension. We conclude that strategies to reduce SOD2 acetylation may have therapeutic potential in the treatment of vascular dysfunction and hypertension.NEW & NOTEWORTHY Essential hypertension is associated with hyperacetylation of key mitochondrial antioxidant SOD2; however, the pathophysiological role of SOD2 acetylation has not been defined. Our animal study of angiotensin II hypertension model shows that deacetylation mimetic SOD2-K68R mutation prevents pathogenic increase in vascular mitochondrial superoxide, abrogates vascular oxidative stress, preserves endothelial nitric oxide, protects endothelial-dependent vasorelaxation, and attenuates hypertension. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and the pathogenesis of hypertension.
{"title":"Deacetylation mimetic mutation of mitochondrial SOD2 attenuates ANG II-induced hypertension by protecting against oxidative stress and inflammation.","authors":"Anna Dikalova, Mingfang Ao, Liliya Tkachuk, Sergey Dikalov","doi":"10.1152/ajpheart.00162.2024","DOIUrl":"10.1152/ajpheart.00162.2024","url":null,"abstract":"<p><p>Almost one-half of adults have hypertension, and blood pressure is poorly controlled in a third of patients despite the use of multiple drugs, likely because of mechanisms that are not affected by current treatments. Hypertension is linked to oxidative stress; however, common antioxidants are ineffective. Hypertension is associated with inactivation of key intrinsic mitochondrial antioxidant, superoxide dismutase 2 (SOD2), due to hyperacetylation, but the role of specific SOD2 lysine residues has not been defined. Hypertension is associated with SOD2 acetylation at lysine 68, and we suggested that deacetylation mimetic mutation of K68 to arginine in SOD2 inhibits vascular oxidative stress and attenuates hypertension. To test this hypothesis, we have developed a new deacetylation mimetic SOD2-K68R mice. We performed in vivo studies in SOD2-K68R mice using angiotensin II (ANG II) model of vascular dysfunction and hypertension. ANG II infusion in wild-type mice induced vascular inflammation and oxidative stress and increased blood pressure to 160 mmHg. SOD2-K68R mutation completely prevented increase in mitochondrial superoxide, abrogated vascular oxidative stress, preserved endothelial nitric oxide production, protected vasorelaxation, and attenuated ANG II-induced hypertension. ANG II and cytokines contribute to vascular oxidative stress and hypertension. Treatment of wild-type aortas with ANG II and cytokines in organoid culture increased mitochondrial superoxide twofold, which was completely prevented in aortas isolated from SOD2-K68R mice. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and pathogenesis of hypertension. We conclude that strategies to reduce SOD2 acetylation may have therapeutic potential in the treatment of vascular dysfunction and hypertension.<b>NEW & NOTEWORTHY</b> Essential hypertension is associated with hyperacetylation of key mitochondrial antioxidant SOD2; however, the pathophysiological role of SOD2 acetylation has not been defined. Our animal study of angiotensin II hypertension model shows that deacetylation mimetic SOD2-K68R mutation prevents pathogenic increase in vascular mitochondrial superoxide, abrogates vascular oxidative stress, preserves endothelial nitric oxide, protects endothelial-dependent vasorelaxation, and attenuates hypertension. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and the pathogenesis of hypertension.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11442025/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141431129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-21DOI: 10.1152/ajpheart.00601.2023
Brianna M Cathey, Anna Bellach, James Troendle, Kevin Smith, Sharon Osgood, Neelam Raja, Beth A Kozel, Mark D Levin
Williams-Beuren syndrome (WBS) is a rare genetic condition caused by a chromosomal microdeletion at 7q11.23. It is a multisystem disorder characterized by distinct facies, intellectual disability, and supravalvar aortic stenosis (SVAS). Those with WBS are at increased risk of sudden death, but mechanisms underlying this remain poorly understood. We recently demonstrated autonomic abnormalities in those with WBS that are associated with increased susceptibility to arrhythmia and sudden cardiac death (SCD). A recently introduced method for heart rate variability (HRV) analysis called "heart rate fragmentation" (HRF) correlates with adverse cardiovascular events (CVEs) and death in studies where heart rate variability (HRV) failed to identify high-risk subjects. Some argue that HRF quantifies nonautonomic cardiovascular modulators. We, therefore, sought to apply HRF analysis to a WBS cohort to determine 1) if those with WBS show differences in HRF compared with healthy controls and 2) if HRF helps characterize HRV abnormalities in those with WBS. Similar to studies of those with coronary artery disease (CAD) and atherosclerosis, we found significantly higher HRF (4 out of 7 metrics) in those with WBS compared with healthy controls. Multivariable analyses showed a weak-to-moderate association between HRF and HRV, suggesting that HRF may reflect HRV characteristics not fully captured by traditional HRV metrics (autonomic markers). We also introduce a new metric inspired by HRF methodology, significant acute rate drop (SARD), which may detect vagal activity more directly. HRF and SARD may improve on traditional HRV measures to identify those at greatest risk for SCD both in those with WBS and in other populations.NEW & NOTEWORTHY This work is the first to apply heart rate fragmentation analyses to individuals with Williams syndrome and posits that the heart rate fragmentation parameter W3 may enable detection and investigation of phenomena underlying the proarrhythmic short-long-short RR interval sequences paradigm known to precede ventricular fibrillation and ventricular tachycardia. It also forwards a novel method for quantifying sinus arrhythmia and sinus pauses that likely correlate with parasympathetic activity.
{"title":"Increased heart rate fragmentation in those with Williams-Beuren syndrome suggests nonautonomic mechanistic contributors to sudden death risk.","authors":"Brianna M Cathey, Anna Bellach, James Troendle, Kevin Smith, Sharon Osgood, Neelam Raja, Beth A Kozel, Mark D Levin","doi":"10.1152/ajpheart.00601.2023","DOIUrl":"10.1152/ajpheart.00601.2023","url":null,"abstract":"<p><p>Williams-Beuren syndrome (WBS) is a rare genetic condition caused by a chromosomal microdeletion at 7q11.23. It is a multisystem disorder characterized by distinct facies, intellectual disability, and supravalvar aortic stenosis (SVAS). Those with WBS are at increased risk of sudden death, but mechanisms underlying this remain poorly understood. We recently demonstrated autonomic abnormalities in those with WBS that are associated with increased susceptibility to arrhythmia and sudden cardiac death (SCD). A recently introduced method for heart rate variability (HRV) analysis called \"heart rate fragmentation\" (HRF) correlates with adverse cardiovascular events (CVEs) and death in studies where heart rate variability (HRV) failed to identify high-risk subjects. Some argue that HRF quantifies nonautonomic cardiovascular modulators. We, therefore, sought to apply HRF analysis to a WBS cohort to determine <i>1</i>) if those with WBS show differences in HRF compared with healthy controls and <i>2</i>) if HRF helps characterize HRV abnormalities in those with WBS. Similar to studies of those with coronary artery disease (CAD) and atherosclerosis, we found significantly higher HRF (4 out of 7 metrics) in those with WBS compared with healthy controls. Multivariable analyses showed a weak-to-moderate association between HRF and HRV, suggesting that HRF may reflect HRV characteristics not fully captured by traditional HRV metrics (autonomic markers). We also introduce a new metric inspired by HRF methodology, significant acute rate drop (SARD), which may detect vagal activity more directly. HRF and SARD may improve on traditional HRV measures to identify those at greatest risk for SCD both in those with WBS and in other populations.<b>NEW & NOTEWORTHY</b> This work is the first to apply heart rate fragmentation analyses to individuals with Williams syndrome and posits that the heart rate fragmentation parameter <i>W</i><sub>3</sub> may enable detection and investigation of phenomena underlying the proarrhythmic short-long-short RR interval sequences paradigm known to precede ventricular fibrillation and ventricular tachycardia. It also forwards a novel method for quantifying sinus arrhythmia and sinus pauses that likely correlate with parasympathetic activity.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11442095/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141431131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-07-12DOI: 10.1152/ajpheart.00195.2024
Danielle X Shane, Daria M Konovalova, Harishkumar Rajendran, Sarah Y Yuan, Yonggang Ma
The thymus, where T lymphocytes develop and mature, is sensitive to insults such as tissue ischemia or injury. The insults can cause thymic atrophy and compromise T-cell development, potentially impairing adaptive immunity. The objective of this study was to investigate whether myocardial infarction (MI) induces thymic injury to impair T lymphopoiesis and to uncover the underlying mechanisms. When compared with sham controls, MI mice at day 7 post-MI exhibited smaller thymus, lower cellularity, as well as less thymocytes at different developmental stages, indicative of T-lymphopoiesis impairment following MI. Accordingly, the spleen of MI mice has less T cells and recent thymic emigrants (RTEs), implying that the thymus of MI mice releases fewer mature thymocytes than sham controls. Interestingly, the secretory function of splenic T cells was not affected by MI. Further experiments showed that the reduction of thymocytes in MI mice was due to increased thymocyte apoptosis. Removal of adrenal glands by adrenalectomy (ADX) prevented MI-induced thymic injury and dysfunction, whereas corticosterone supplementation in ADX + MI mice reinduced thymic injury and dysfunction, indicating that glucocorticoids mediate thymic damage triggered by MI. Eosinophils play essential roles in thymic regeneration postirradiation, and eosinophil-deficient mice exhibit impaired thymic recovery after sublethal irradiation. Interestingly, the thymus was fully regenerated in both wild-type and eosinophil-deficient mice at day 14 post-MI, suggesting that eosinophils are not critical for thymus regeneration post-MI. In conclusion, our study demonstrates that MI-induced glucocorticoids trigger thymocyte apoptosis and impair T lymphopoiesis, resulting in less mature thymocyte release to the spleen.NEW & NOTEWORTHY The thymus is essential for maintaining whole body T-cell output. Thymic injury can adversely affect T lymphopoiesis and T-cell immune response. This study demonstrates that MI induces thymocyte apoptosis and compromises T lymphopoiesis, resulting in fewer releases of mature thymocytes to the spleen. This process is mediated by glucocorticoids secreted by adrenal glands. Therefore, targeting glucocorticoids represents a novel approach to attenuate post-MI thymic injury.
胸腺是 T 淋巴细胞发育和成熟的场所,对组织缺血或损伤等损伤非常敏感。这些损伤会导致胸腺萎缩,影响T细胞的发育,从而可能损害适应性免疫。本研究旨在探讨心肌梗死(MI)是否会诱发胸腺损伤,从而损害T淋巴细胞的生成,并揭示其潜在机制。与假对照组相比,心肌梗死后第7天的心肌梗死小鼠胸腺较小、细胞度较低,不同发育阶段的胸腺细胞也较少,表明心肌梗死后T淋巴细胞生成受损。相应地,MI 小鼠脾脏中的 T 细胞和近期胸腺移植物(RTE)较少,这意味着 MI 小鼠胸腺释放的成熟胸腺细胞比假对照组少。有趣的是,脾脏 T 细胞的分泌功能并未受到 MI 的影响。进一步的实验表明,MI 小鼠胸腺细胞的减少是由于胸腺细胞凋亡增加所致。通过肾上腺切除术(ADX)切除肾上腺可防止MI诱发的胸腺损伤和功能障碍,而在ADX+MI小鼠体内补充皮质酮可重新诱发胸腺损伤和功能障碍,这表明糖皮质激素介导了MI引发的胸腺损伤。嗜酸性粒细胞在辐照后胸腺再生中发挥着重要作用,嗜酸性粒细胞缺乏的小鼠在亚致死性辐照后胸腺恢复受损。有趣的是,野生型和嗜酸性粒细胞缺陷型小鼠的胸腺在辐照后第 14 天完全再生,这表明嗜酸性粒细胞对辐照后胸腺再生并不至关重要。总之,我们的研究表明,心肌梗死诱导的糖皮质激素会引发胸腺细胞凋亡并损害T淋巴细胞生成,从而导致向脾脏释放的成熟胸腺细胞减少。
{"title":"Glucocorticoids impair T lymphopoiesis after myocardial infarction.","authors":"Danielle X Shane, Daria M Konovalova, Harishkumar Rajendran, Sarah Y Yuan, Yonggang Ma","doi":"10.1152/ajpheart.00195.2024","DOIUrl":"10.1152/ajpheart.00195.2024","url":null,"abstract":"<p><p>The thymus, where T lymphocytes develop and mature, is sensitive to insults such as tissue ischemia or injury. The insults can cause thymic atrophy and compromise T-cell development, potentially impairing adaptive immunity. The objective of this study was to investigate whether myocardial infarction (MI) induces thymic injury to impair T lymphopoiesis and to uncover the underlying mechanisms. When compared with sham controls, MI mice at <i>day 7</i> post-MI exhibited smaller thymus, lower cellularity, as well as less thymocytes at different developmental stages, indicative of T-lymphopoiesis impairment following MI. Accordingly, the spleen of MI mice has less T cells and recent thymic emigrants (RTEs), implying that the thymus of MI mice releases fewer mature thymocytes than sham controls. Interestingly, the secretory function of splenic T cells was not affected by MI. Further experiments showed that the reduction of thymocytes in MI mice was due to increased thymocyte apoptosis. Removal of adrenal glands by adrenalectomy (ADX) prevented MI-induced thymic injury and dysfunction, whereas corticosterone supplementation in ADX + MI mice reinduced thymic injury and dysfunction, indicating that glucocorticoids mediate thymic damage triggered by MI. Eosinophils play essential roles in thymic regeneration postirradiation, and eosinophil-deficient mice exhibit impaired thymic recovery after sublethal irradiation. Interestingly, the thymus was fully regenerated in both wild-type and eosinophil-deficient mice at <i>day 14</i> post-MI, suggesting that eosinophils are not critical for thymus regeneration post-MI. In conclusion, our study demonstrates that MI-induced glucocorticoids trigger thymocyte apoptosis and impair T lymphopoiesis, resulting in less mature thymocyte release to the spleen.<b>NEW & NOTEWORTHY</b> The thymus is essential for maintaining whole body T-cell output. Thymic injury can adversely affect T lymphopoiesis and T-cell immune response. This study demonstrates that MI induces thymocyte apoptosis and compromises T lymphopoiesis, resulting in fewer releases of mature thymocytes to the spleen. This process is mediated by glucocorticoids secreted by adrenal glands. Therefore, targeting glucocorticoids represents a novel approach to attenuate post-MI thymic injury.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11442026/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141589382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-21DOI: 10.1152/ajpheart.00400.2024
Madeline G Burghaze, Matthew W Gorr
{"title":"Understanding the estrogen paradox of pulmonary arterial hypertension in the context of right ventricular function.","authors":"Madeline G Burghaze, Matthew W Gorr","doi":"10.1152/ajpheart.00400.2024","DOIUrl":"10.1152/ajpheart.00400.2024","url":null,"abstract":"","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141431132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-28DOI: 10.1152/ajpheart.00315.2024
Bert Bond, Harrison Hurlstone, David M Köditz, Alice B Lester, Harry Mould, Thomas Tennant, Amber Thorington
Brief, repeated cycles of limb ischemia and reperfusion [ischemic preconditioning (IPC)] can protect against vascular insult. Few papers have considered the effect of IPC on resting vascular function, and no single study has simultaneously considered the local (trained arm) and remote (untrained arm) effects of a single session of IPC and following repeated sessions. We determined macrovascular [allometrically scaled flow-mediated dilation (FMD)] and microvascular [cutaneous vascular conductance (CVC)] function in healthy adults before, immediately post, 20 min post, and 24 h post a single session of IPC (4 × 5 min of single arm ischemia). These outcomes also were remeasured 24 h after six IPC sessions, performed over 2 wk. FMD and CVC increased in both arms 20 min post [FMD mean difference (MD) 1.1%, P < 0.001; CVC MD 0.08 arbitrary units (AU), P = 0.004] but not 24 h post (FMD MD -0.2%, P = 0.459; CVC MD -0.02 AU, P = 0.526] a single session of IPC, with no differences between trained and untrained arms. Although FMD did not increase 24 h after one IPC session, it was elevated in both arms 24 h after the sixth session (MD 1.2%, P = 0.009). CVC was not altered in either arm 24 h after the last IPC session. These data indicate that the local and remote effects of IPC on vascular health may be equivalent and that the benefits to FMD may be greater with sustained training compared with a single IPC exposure.
{"title":"Remote and local effects of ischemic preconditioning on vascular function: a case for cumulative benefit.","authors":"Bert Bond, Harrison Hurlstone, David M Köditz, Alice B Lester, Harry Mould, Thomas Tennant, Amber Thorington","doi":"10.1152/ajpheart.00315.2024","DOIUrl":"10.1152/ajpheart.00315.2024","url":null,"abstract":"<p><p>Brief, repeated cycles of limb ischemia and reperfusion [ischemic preconditioning (IPC)] can protect against vascular insult. Few papers have considered the effect of IPC on resting vascular function, and no single study has simultaneously considered the local (trained arm) and remote (untrained arm) effects of a single session of IPC and following repeated sessions. We determined macrovascular [allometrically scaled flow-mediated dilation (FMD)] and microvascular [cutaneous vascular conductance (CVC)] function in healthy adults before, immediately post, 20 min post, and 24 h post a single session of IPC (4 × 5 min of single arm ischemia). These outcomes also were remeasured 24 h after six IPC sessions, performed over 2 wk. FMD and CVC increased in both arms 20 min post [FMD mean difference (MD) 1.1%, <i>P</i> < 0.001; CVC MD 0.08 arbitrary units (AU), <i>P</i> = 0.004] but not 24 h post (FMD MD -0.2%, <i>P</i> = 0.459; CVC MD -0.02 AU, <i>P</i> = 0.526] a single session of IPC, with no differences between trained and untrained arms. Although FMD did not increase 24 h after one IPC session, it was elevated in both arms 24 h after the sixth session (MD 1.2%, <i>P</i> = 0.009). CVC was not altered in either arm 24 h after the last IPC session. These data indicate that the local and remote effects of IPC on vascular health may be equivalent and that the benefits to FMD may be greater with sustained training compared with a single IPC exposure.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141465680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-14DOI: 10.1152/ajpheart.00390.2024
Anna Kosmach, Timothy M Sveeggen, Pooneh Bagher
{"title":"Sublingual microcirculatory function as a prognostic indicator of general microvascular health.","authors":"Anna Kosmach, Timothy M Sveeggen, Pooneh Bagher","doi":"10.1152/ajpheart.00390.2024","DOIUrl":"10.1152/ajpheart.00390.2024","url":null,"abstract":"","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141316582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}