Increased Kinin Levels and Decreased Responsiveness to Kinins During Aging

Associations Between Plasma Kinin B1 Receptor Levels and the Presence and Severity of Coronary Artery Disease

Aim: Kinin B1 receptor (KB1R) was shown to be up-regulated in human carotid atherosclerotic lesions. Serum KB1R levels were also reported to be high in patients with stroke. However, KB1R deficiency increased atherosclerotic lesions. Therefore, the role of KB1R in atherosclerosis remains unclear. Moreover, no study has reported blood KB1R levels in patients with coronary artery disease (CAD).

Methods: We measured plasma KB1R levels in 375 patients undergoing coronary angiography. The severity of CAD was represented as the numbers of ＞50% stenotic vessels and segments and the severity score.

Results: CAD was found in 197 patients, of whom 89 had 1-vessel disease (1-VD), 62 had 2-VD, and 46 had 3-VD. Plasma KB1R levels were higher in 197 patients with CAD than in 178 without CAD (median 83.3 vs. 73.7 pg/mL, p ＜0.01). A stepwise increase in KB1R levels was found depending on the number of stenotic vessels: 77.1 in 1-VD, 87.8 in 2-VD, and 88.5 pg/mL in 3-VD ( p ＜0.025). A high KB1R level (＞90.0 pg/mL) was present in 30% of patients with CAD(-), 39% of 1-VD, 50% of 2-VD, and 48% of 3-VD ( p ＜0.025). KB1R levels correlated with the number of stenotic segments and the severity score (r=0.14 and r=0.17, p ＜0.01). In multivariate analysis, KB1R levels were an independent factor associated with CAD. Odds ratio for CAD was 1.62 (95%CI=1.02-2.58) for high KB1R level ＞90.0 pg/mL.

Conclusion: Plasma KB1R levels in patients with CAD were high and were associated with the presence and severity of CAD independent of atherosclerotic risk factors.

The natural course of hereditary angioedema in a Chinese cohort

Background

Hereditary angioedema (HAE) is a rare disease with potential life-threatening risks. To study the natural course of HAE under therapy-free conditions throughout patient life is essential for practitioners and patients to avoid possible risk factors and guide treatment.

Objectives

Describe the natural course of HAE and explore possible risk factors, providing new clues for guiding clinical prevention and treatment.

Methods

A web-based survey was conducted in 103 Chinese patients with type 1 HAE. Disease progression at different age stages was provided by each participant. The data for exploring the natural course of HAE composed of two parts: one came from the participants who had never adopted any prophylactic drug for HAE; the other was from the patients with a history of medication, but only the periods before they got confirmed diagnosis and received medications were analyzed. The demographic characteristics, lifestyles, disease severity, and family history were also collected.

Results

Among 103 patients, 14 (13.6%) had their first HAE attack before 10 years old and 51 (49.5%) between 10 and 19. The disease worsened in 83.3% of the patients in their twenties. The proportion of patients with symptoms alleviated increased after the age of 30 years old, but the disease maintained relatively severe in most cases before 50. The participants also reported 233 members shared similar symptoms of angioedema in their family and 30 had died of laryngeal edema with the median death age of 46 years old. The disease severity was not observed to be affected significantly by gender, BMI, alcohol or smoking.

Conclusions

We summarized HAE progression patterns under therapy-free conditions, showing the natural course of HAE development along with aging. Long-term prophylaxis and symptomatic treatment are recommended for all HAE patients, especially young and middle-aged and might be adjusted depending on the disease progression.

Identifying pathophysiological bases of disease in COVID-19

COVID-19 is an infectious disease caused by the SARS-CoV-2 virus that can affect lung physiology encompassing a wide spectrum of severities, ranging from asymptomatic and mild symptoms to severe and fatal cases; the latter including massive neutrophil infiltration, stroke and multiple organ failure. Despite many recents findings, a clear mechanistic description underlying symptomatology is lacking. In this article, we thoroughly review the available data involving risk factors, age, gender, comorbidities, symptoms of disease, cellular and molecular mechanisms and the details behind host/pathogen interaction that hints at the existence of different pathophysiological mechanisms of disease. There is clear evidence that, by targeting the angiotensin-converting enzyme II (ACE2) -its natural receptor-, SARS-CoV-2 would mainly affect the renin-angiotensin-aldosterone system (RAAS), whose imbalance triggers diverse symptomatology-associated pathological processes. Downstream actors of the RAAS cascade are identified, and their interaction with risk factors and comorbidities are presented, rationalizing why a specific subgroup of individuals that present already lower ACE2 levels is particularly more susceptible to severe forms of disease. Finally, the notion of endotype discovery in the context of COVID-19 is introduced. We hypothesize that COVID-19, and its associated spectrum of severities, is an umbrella term covering different pathophysiological mechanisms (endotypes). This approach should dramatically accelerate our understanding and treatment of disease(s), enabling further discovery of pathophysiological mechanisms and leading to the identification of specific groups of patients that may benefit from personalized treatments.

Bradykinin -induced vasodilatation: Role of age, ACE1-inhibitory peptide, mas- and bradykinin receptors

Bradykinin exerts its vascular actions via two types of receptors, the non-constitutively expressed bradykinin receptor type 1 (BR1) and the constitutive type 2 receptor (BR2). Bradykinin-induced vasorelaxation is age-dependent, a phenomenon related to the varying amounts of BR1 and BR2 in the vasculature. Isoleucine-proline-proline (Ile-Pro-Pro), a bioactive tripeptide, lowers elevated blood pressure and improves impaired endothelium-dependent vasorelaxation in hypertensive rats. It inhibits angiotensin converting enzyme 1 (ACE1). Other mechanisms of action have also been postulated. The aims of the study were to clarify the underlying mechanisms of the age-dependency of bradykinin-induced vasodilatation such as the roles of the two bradykinin receptors, the mas-receptor and synergism with Ile-Pro-Pro. The vascular response studies were conducted using mesenteric artery and aorta rings from normotensive 6 wk. (young) and 22 wk. (old) Wistar rats. Cumulative dosing of acetylcholine, bradykinin and angiotensin(1-7) (Ang(1-7))were tested in phenylephrine-induced vasoconstriction with or without 10min pre-incubation with antagonists against BR1-, BR2- or mas-receptors, Ang(1-7) or ACE1-inhibitors captopril and Ile-Pro-Pro. The bradykinin-induced vasorelaxation in vitro was age-dependent and it was improved by pre-incubation with Ile-Pro-Pro, especially in old rats with endothelial dysfunction. The mas-receptor antagonist, D-Pro₇-Ang(1-7) abolished bradykinin-induced relaxation totally. Interestingly, BR1 and BR2 antagonists only slightly reduced bradykinin-induced vasorelaxation, as an evidence for the involvement of other mechanisms in addition to receptor activation. In conclusion, bradykinin-induced vasorelaxation was age-dependent and Ile-Pro-Pro improved it. Mas receptor antagonist abolished relaxation while bradykinin receptor antagonist only slightly reduced it, suggesting that bradykinin-induced vasorelaxation is regulated also by other mechanisms than the classical BR1/BR2 pathway.

Unraveling the Pivotal Role of Bradykinin in ACE Inhibitor Activity

Historically, the first described effect of an angiotensin converting enzyme (ACE) inhibitor was an increased activity of bradykinin, one of the substrates of ACE. However, in the subsequent years, molecular models describing the mechanism of action of ACE inhibitors in decreasing blood pressure and cardiovascular risk have focused mostly on the renin-angiotensin system. Nonetheless, over the last 20 years, the importance of bradykinin in regulating vasodilation, natriuresis, oxidative stress, fibrinolysis, inflammation, and apoptosis has become clearer. The affinity of ACE appears to be higher for bradykinin than for angiotensin I, thereby suggesting that ACE inhibitors may be more effective inhibitors of bradykinin degradation than of angiotensin II production. Data describing the effect of ACE inhibition on bradykinin signaling support the hypothesis that the most cardioprotective benefits attributed to ACE inhibition may be due to increased bradykinin signaling rather than to decreased angiotensin II signaling, especially when high dosages of ACE inhibitors are considered. In particular, modulation of bradykinin in the endothelium appears to be a major target of ACE inhibition. These new mechanistic concepts may lead to further development of strategies enhancing the bradykinin signaling.

Cerebrovascular expression of proteins related to inflammation, oxidative stress and neurotoxicity is altered with aging

Background

Most neurodegenerative diseases are age-related disorders; however, how aging predisposes the brain to disease has not been adequately addressed. The objective of this study is to determine whether expression of proteins in the cerebromicrovasculature related to inflammation, oxidative stress and neurotoxicity is altered with aging.

Methods

Brain microvessels are isolated from Fischer 344 rats at 6, 12, 18 and 24 months of age. Levels of interleukin (IL)-1β and IL-6 RNA are determined by RT-PCR and release of cytokines into the media by ELISA. Vessel conditioned media are also screened by ELISA for IL-1α, monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α, (TNFα), and interferon γ (IFNγ). Immunofluorescent analysis of brain sections for IL-1β and IL-6 is performed.

Results

Expression of IL-1β and IL-6, both at RNA and protein levels, significantly (p < 0.01) decreases with age. Levels of MCP-1, TNFα, IL-1α, and IFNγ are significantly (p < 0.05-0.01) lower in 24 month old rats compared to 6 month old animals. Immunofluorescent analysis of brain vessels also shows a decline in IL-1β and IL-6 in aged rats. An increase in oxidative stress, assessed by increased carbonyl formation, as well as a decrease in the antioxidant protein manganese superoxide dismutase (MnSOD) is evident in vessels of aged animals. Finally, addition of microvessel conditioned media from aged rats to neuronal cultures evokes significant (p < 0.001) neurotoxicity.

Conclusions

These data demonstrate that cerebrovascular expression of proteins related to inflammation, oxidative stress and neurotoxicity is altered with aging and suggest that the microvasculature may contribute to functional changes in the aging brain.

Modulation of granulocyte functions by peptide YY in the rat: age-related differences in Y receptors expression and plasma dipeptidyl peptidase 4 activity

It has been acknowledged that aging exerts detrimental effects on cells of the innate immune system and that neuropeptides, including neuropeptide Y (NPY) and NPY-related peptides fine-tune the activity of these cells through a receptor specific mechanism. The present study investigated the age-dependent potential of peptide YY (PYY) to modulate different granulocyte functions. The PYY reduced the carrageenan-elicited granulocyte accumulation into the air-pouch of aged (24 months) rats, and markedly decreased the phagocytosis of zymosan, as well as the H(2)O(2) production, when applied in vivo (20 microg/air-pouch). The anti-inflammatory effect of PYY was less prominent in adult (8 months) and young (3 months) rats. However, the proportions of granulocytes expressing Y1, Y2 and Y5 receptor subtypes were significantly lower in both aged and young rats when compared to adult rats. Furthermore, the aging was found to be associated with the diminished dipeptidyl peptidase 4 (DP4, an enzyme converting the NPY and PYY to Y2/Y5 receptor selective agonists) activity in plasma. In conclusion, the diverse age-related anti-inflammatory effect of PYY in rats originates from different expression levels of Y1, Y2, and Y5 receptor subtypes in addition to different plasma DP4 activity.

Bradykinin protects against oxidative stress-induced endothelial cell senescence

Premature aging (senescence) of endothelial cells might play an important role in the development and progression of hypertension and atherosclerosis. We hypothesized that bradykinin, a hormone that mediates vasoprotective effects of angiotensin-converting enzyme inhibitors, protects endothelial cells from oxidative stress-induced senescence. Bradykinin treatment (0.001 to 1 nmol/L) dose-dependently decreased senescence induced by 25 micromol/L of H(2)O(2) in cultured bovine aortic endothelial cells, as witnessed by a complete inhibition of increased senescent cell numbers and a 34% reduction of the levels of the senescence-associated cell cycle protein p21. Because H(2)O(2) induces senescence through superoxide-induced DNA damage, single-cell DNA damage was measured by comet assay. Bradykinin reduced DNA damage to control levels. The protective effect of bradykinin also resulted in a significant increase in the migration of H(2)O(2)-treated bovine aorta endothelial cells in an in vitro endothelial injury model, or "scratch" assay. The protective effect of bradykinin was abolished by the bradykinin B2 receptor antagonist HOE-140 and the NO production inhibitor N(omega)-methyl-L-arginine acetate salt. Therefore, we conclude that bradykinin protects endothelial cells from superoxide-induced senescence through bradykinin B2 receptor- and NO-mediated inhibition of DNA damage.