Hypertension, RAS, and gender: what is the role of aminopeptidases?

Possible protective role of 17β-estradiol against COVID-19

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is the virus that causes coronavirus disease 2019 (COVID-19); a worldwide pandemic as declared by the World Health Organization (WHO). SARS-CoV-2 appears to infect cells by first binding and priming its viral-spike proteins with membrane-associated angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). Through the coordinated actions of ACE2 and TMPRSS2, SARS-CoV-2 spike proteins fuse with plasma membranes and ultimately the virus enters cells. ACE2 is integral to the renin-angiotensin-aldosterone system (RAAS), and SARS-CoV-2 down-regulates protein expression levels of ACE2. Once infected, patients typically develop acute respiratory distress syndrome (ARDS) and a number of other severe complications that result in a high rate of fatality, especially in older (>60 years) adults and in people with pre-existing medical conditions. Data now indicate clearly that among people of all age groups, COVID-19 fatalities are higher in men than women. Here, attention is focused on these sex differences and posit a role of estrogen in these differences as well as possible therapeutic and protective actions of 17β-estradiol against COVID-19.

Obesity parameters, physical activity, and physical fitness are correlated with serum dipeptidyl peptidase IV activity in a healthy population

Objective

To determine whether obesity, physical fitness, and physical activity parameters are associated with the enzymatic activity of serum dipeptidyl peptidase IV (sDPPIV) in a sample of healthy women and men.

Design and methods

We have correlated parameters of obesity, physical fitness, and physical activity with sDPPIV activity in 374 healthy subjects (age: 60.7 ± 6.9 years, body mass index: 26.1 ± 4.1 kg/m²). Enzymatic activity was analyzed using spectrofluorimetry, body composition was assessed by impedanciometry, physical fitness data were obtained using the Senior Fitness Test, and physical activity data were collected by accelerometer. Pearson's partial correlation analysis was applied to determine the relationship between DPPIV activity and the rest of parameters and significantly correlated variables were introduced into linear regression models to predict DPPIV.

Results

Serum DPPIV activity was negatively associated with obesity parameters such as body mass (r = -0.112), body mass index (BMI) (r = -0.147), waist circumference (r = -0.164), waist-to-hip ratio (-0.104), and percentage of fat mass (r = -0.185). Serum DPPIV activity was positively associated with cardiovascular fitness (r = 0.138), total amount of physical activity (r = 0.153), and time spent doing light exercise (r = 0.184). Regression models revealed sex differences in enzyme activity with overall activity higher in women than in men (β = 0.437, p < 0.001). Further, percent fat mass was an independent negative predictor of DPPIV activity (β = -0.184, p = 0.001). Serum DPPIV activity was positively predicted based on the amount of time spent doing light physical activity (β = 0.167, p = 0.001).

Conclusion

Our results demonstrate that sDPPIV activity is positively associated with healthier parameters regarding fatness, fitness and physical activity.

Sex differences in the aging pattern of renin-angiotensin system serum peptidases

Background

Serum peptidases, such as angiotensin-converting enzyme (ACE), angiotensin-converting enzyme-2 (ACE2), neutral endopeptidase (NEP), aminopeptidase N (APN), and aminopeptidase A (APA), are important elements of the renin–angiotensin system (RAS). Dysregulation of these enzymes has been associated with hypertension and cardiovascular risk. In the present study, serum activities of RAS peptidases were analyzed to evaluate the existence of sexual differences, with a possible different pattern in pre- and post-andropausal/post-menopausal participants.

Methods

One hundred and eighteen healthy men and women between 41 and 70 years of age (58 women and 60 men) were recruited to participate in the study. Serum RAS-regulating enzymes were measured by spectrofluorimetry. Enzymatic activity was recorded as units of enzyme per milliliter of serum (U/mL).

Results

Significantly lower serum APA activity was observed in men with respect to women; no sex differences were detected for ACE, ACE2, NEP, or APN. Significantly lower APA and ACE serum activity were observed in older men compared to older women. In contrast, younger (<55 years) men had significantly higher values of NEP serum activity than younger women. Significantly lower ACE serum activity was detected in older men compared to younger men. In women, significantly higher ACE2 serum activity was observed in older women compared to younger women.

Conclusions

These results suggest a differential effect of aging on the activity of RAS enzymes in men and women, especially with respect to the breakpoint of andropausia/menopausia, on the critical serum enzymatic activities of the RAS, which could correlate with sexual differences in cardiovascular risk.

Insufficient and excessive amounts of sleep increase the risk of premature death from cardiovascular and other diseases: the Multiethnic Cohort Study

OBJECTIVE

To explore an independent association between self-reported sleep duration and cause-specific mortality.

METHODS

Data were obtained from the Multiethnic Cohort Study conducted in Los Angeles and Hawaii.

RESULTS

Among 61,936 men and 73,749 women with no history of cancer, heart attack or stroke, 19,335 deaths occurred during an average 12.9year follow-up. Shorter (≤5h/day) and longer (≥9h/day) sleepers of both sexes (vs. 7h/day) had an increased risk of all-cause and cardiovascular disease (CVD) mortality, but not of cancer mortality. Multivariable hazard ratios for CVD mortality were 1.13 (95% CI 1.00-1.28) for ≤5h/day and 1.22 (95% CI 1.09-1.35) for ≥9h/day among men; and 1.20 (95% CI 1.05-1.36) for ≤5h/day and 1.29 (95% CI 1.13-1.47) for ≥9h/day among women. This risk pattern was not heterogeneous across specific causes of CVD death among men (Phetero 0.53) or among women (Phetero 0.72). The U-shape association for all-cause and CVD mortality was observed in all five ethnic groups included in the study and by subgroups of age, smoking status, and body mass index.

CONCLUSION

Insufficient or excessive amounts of sleep were associated with increased risk of mortality from CVD and other diseases in a multiethnic population.

Blunted blood pressure response and elevated plasma adiponectin levels in female Sprague Dawley rats

BACKGROUND

Premenopausal women have lower blood pressure (BP) levels than men of similar age. Adiponectin has been shown to play a role in the pathogenesis of hypertension. The aim of the present study was to compare the effect of various stress stimuli on BP and plasma adiponectin levels in male and female Sprague Dawley (SD) rats.

METHODS

In three experimental models of hypertension, fructose-enriched diet, high salt diet, or L-NAME, were administered for up to 4 weeks. BP, metabolic parameters, and plasma adiponectin were measured at baseline and during the studies. The fructose diet protocol was repeated in female rats for 2 weeks with the addition of testosterone injections or vehicle.

RESULTS

Females, in contrast to males, did not develop fructose-induced hypertension. Total plasma triglycerides (TGs) were half in females at baseline (P < 0.001) and a third at 4 weeks (P < 0.05). Plasma insulin levels were 23% lower in females than in males at baseline (P < 0.05) and 42% lower after 4 weeks of fructose-enriched diet (P = 0.001). Plasma adiponectin levels were 65% higher in females than in males at baseline (P = 0.001) and 45% higher after 4 weeks of fructose-enriched diet (P < 0.05). Furthermore, female rats showed blunted BP response and elevated plasma adiponectin in the salt-induced and L-NAME-induced hypertension models. Testosterone injection to female rats reduced plasma adiponectin and reversed the blunted BP response.

CONCLUSIONS

Elevated plasma adiponectin levels, perhaps due to lack of suppression by testosterone, are associated with a blunting of BP response in female compared to male SD rats.

Altered dipeptidyl peptidase IV and prolyl endopeptidase activities in chronic tonsillitis, tonsillar hyperplasia and adenoid hyperplasia

OBJECTIVE

To analyse peptidase activities in the removed tonsils and adenoids from patients with chronic tonsillitis, tonsillar hyperplasia and adenoid hyperplasia.

METHODS

We have analyzed 48 tissue samples from patients undergoing tonsillectomy and adenoidectomy for chronic tonsillitis, tonsillar hyperplasia or adenoid hyperplasia. Tonsillectomy and adenoidectomy samples were collected and frozen for later enzyme analysis. The catalytic activity of a pool of peptidases (dipeptidyl peptidase IV, prolyl endopeptidase, aminopeptidase A, aminopeptidase N, aspartyl aminopeptidase, aminopeptidase B, neutral endopeptidase, pyroglutamyl peptidase I, puromycin-sensitive aminopeptidase and cystinyl aminopeptidase) was measured fluorometrically.

RESULTS

The activity of prolyl endopeptidase was higher in tonsillar hyperplasia and adenoid hyperplasia than in chronic tonsillitis. On the contrary, dipeptidyl peptidase IV activity was higher in chronic tonsillitis than in hypertrophic tissues. When data were stratified by age and gender, dipeptidyl peptidase IV was also found to be more active in adult and male chronic tonsillitis tissues. Inversely, dipeptidyl peptidase IV activity was higher in tissues of females with tonsillar hyperplasia.

CONCLUSIONS

These data indicate the involvement of dipeptidyl peptidase IV and prolyl endopeptidase in the mechanisms underlying chronic tonsillitis, tonsillar hyperplasia and adenoid hyperplasia.

Women and heart disease

In the United States heart disease causes more than one-third of all deaths and most of these occur in women, not men, although women and health care professionals alike continue to view death from heart disease as a threat primarily to middle-aged men. The disparity between genders in the incidence of cardiovascular disease (CVD) may be the result of significant differences in both cardiovascular risk factors and presentation between men and women. This article reviews recent data regarding unique sex-specific characteristics of both risk for, and presentation of, CVD in women.

Cardiovascular disease in women

The rates of cardiovascular disease (CVD) have decreased significantly for men over the past few decades, but similar reductions have not occurred in women. Consequently, CVD remains the leading killer of women in the United States. Men usually develop heart disease earlier than women, but women develop heart disease more rapidly once menopause has occurred. A review of risk factors that are common between men and women demonstrates some notable sex-dependent differences. Many of these changes appear related to the hormonal changes that occur in menopause, such as the development of hypertension, changes in lipid concentrations, and central adiposity. In addition, diabetes is a more significant risk factor for CVD in women than men. Sociologic and physiologic factors need to be considered in treatment of risk factors, such as smoking, lack of exercise, obesity, and depression. Prevention is known to significantly reduce CVD risk, but new goals are being established for women as the sex-dependent differences have become apparent.