Inflammation-Accelerated Senescence and the Cardiovascular System: Mechanisms and Perspectives. Int J Mol Sci. 2018;19. [PMID: 30469478 PMCID: PMC6321367 DOI: 10.3390/ijms19123701]

Inflammation, Frailty and Cardiovascular Disease

Chronic inflammation, which is called "inflamm-aging" , is characterized by an increased level of inflammatory cytokines in response to physiological and environmental stressors, and causes the immune system to function consistently at a low level, even though it is not effective. Possible causes of inflammaging include genetic susceptibility, visceral obesity, changes in gut microbiota and permeability, chronic infections and cellular senescence. Inflammation has a role in the development of many age-related diseases, such as frailty. Low grade chronic inflammation can also increase the risk of atherosclerosis and insulin resistance which are the leading mechanisms in the development of cardiovascular diseases (CVD). As it is well known that the risk of CVD is higher in older people with frailty and the risk of frailty is higher in patients with CVD, there may be relationship between inflammation and the development of CVD and frailty. Therefore, this important issue will be discussed in this chapter.

Association between periodontal inflammation and hypertension using periodontal inflamed surface area and bleeding on probing

AIM

Periodontitis is a relapsing-remitting disease. Compared with bleeding on probing (BoP), expression of disease activity, periodontal inflamed surface area (PISA), incorporates chronic disease parameters. We tested the association of PISA and BoP with blood pressure (BP) in NHANES III.

MATERIALS AND METHODS

A total of 8,614 subjects (≥30 years) with complete periodontal and BP examinations were enrolled. PISA was derived from periodontal probing depth and BoP. The association of PISA and BoP with high/uncontrolled BP was examined by multiple-adjusted models. Inflammatory markers were tested as possible mediators. A machine learning (ML) approach was used to define the relative importance of PISA and BoP and estimate the power of BP status prediction.

RESULTS

Compared to no inflammation, severe PISA and BoP were associated with 43% (p < .001) and 32% (p = .006) higher odds of high/uncontrolled BP (≥130/80 mmHg), and with higher systolic BP by ≈4 (p < .001) and 5 (p < .001) mmHg, respectively. Inflammatory markers appeared to mediate this association with various extents, without threshold effect. BoP predicted high/uncontrolled BP more efficiently than PISA using ML.

CONCLUSION

PISA and BoP describe the association of periodontal inflammation and hypertension with subtle differences. The contribution of local inflammation to the global inflammatory burden might explain the observed findings.

Honokiol antagonizes doxorubicin‑induced cardiomyocyte senescence by inhibiting TXNIP‑mediated NLRP3 inflammasome activation

Senescence of cardiomyocytes is considered a key factor for the occurrence of doxorubicin (Dox)‑associated cardiomyopathy. The NOD‑like receptor family pyrin domain‑containing 3 (NLRP3) inflammasome is reported to be involved in the process of cellular senescence. Furthermore, thioredoxin‑interactive protein (TXNIP) is required for NLRP3 inflammasome activation and is considered to be a key component in the regulation of the pathogenesis of senescence. Studies have demonstrated that pretreatment with honokiol (Hnk) can alleviate Dox‑induced cardiotoxicity. However, the impact of Hnk on cardiomyocyte senescence elicited by Dox and the underlying mechanisms remain unclear. The present study demonstrated that Hnk was able to prevent Dox‑induced senescence of H9c2 cardiomyocytes, indicated by decreased senescence‑associated β‑galactosidase (SA‑β‑gal) staining, as well as decreased expression of p16INK4A and p21. Hnk also inhibited TXNIP expression and NLRP3 inflammasome activation in Dox‑stimulated H9c2 cardiomyocytes. When TXNIP expression was enforced by adenovirus‑mediated gene overexpression, the NLRP3 inflammasome was activated, which led to inhibition of the anti‑inflammation and anti‑senescence effects of Hnk on H9c2 cardiomyocytes under Dox treatment. Furthermore, adenovirus‑mediated TXNIP‑silencing inhibited the NLRP3 inflammasome. Consistently, TXNIP knockdown enhanced the anti‑inflammation and anti‑senescence effects of Hnk on H9c2 cardiomyocytes under Dox stimulation. In summary, Hnk was found to be effective in protecting cardiomyocytes against Dox‑stimulated senescence. This protective effect was mediated via the inhibition of TXNIP expression and the subsequent suppression of the NLRP3 inflammasome. These results demonstrated that Hnk may be of value as a cardioprotective drug by inhibiting cardiomyocyte senescence.

Dysfunctional stem and progenitor cells impair fracture healing with age

Successful fracture healing requires the simultaneous regeneration of both the bone and vasculature; mesenchymal stem cells (MSCs) are directed to replace the bone tissue, while endothelial progenitor cells (EPCs) form the new vasculature that supplies blood to the fracture site. In the elderly, the healing process is slowed, partly due to decreased regenerative function of these stem and progenitor cells. MSCs from older individuals are impaired with regard to cell number, proliferative capacity, ability to migrate, and osteochondrogenic differentiation potential. The proliferation, migration and function of EPCs are also compromised with advanced age. Although the reasons for cellular dysfunction with age are complex and multidimensional, reduced expression of growth factors, accumulation of oxidative damage from reactive oxygen species, and altered signaling of the Sirtuin-1 pathway are contributing factors to aging at the cellular level of both MSCs and EPCs. Because of these geriatric-specific issues, effective treatment for fracture repair may require new therapeutic techniques to restore cellular function. Some suggested directions for potential treatments include cellular therapies, pharmacological agents, treatments targeting age-related molecular mechanisms, and physical therapeutics. Advanced age is the primary risk factor for a fracture, due to the low bone mass and inferior bone quality associated with aging; a better understanding of the dysfunctional behavior of the aging cell will provide a foundation for new treatments to decrease healing time and reduce the development of complications during the extended recovery from fracture healing in the elderly.

Low Density Lipoprotein (LDL) Cholesterol as a Causal Role for Atherosclerotic Disease: Potential Role of PCSK9 Inhibitors

Proprotein convertase subtilisin/kexin type 9 (PCSK9)-related discoveries of the turn of the century have translated into substantial novelty in dyslipidemia treatment in the last 5 years. With chronic preventable atherosclerotic cardiovascular diseases (ASCVD) representing an epidemic of morbidity and mortality worldwide, low-density lipoprotein cholesterol (LDL-c) reduction represents a public health priority. By overcoming two major statin-related issues, namely intolerance and ineffectiveness, PCSK9 inhibitors have offered a safe and effective option in selected clinical settings where LDL-c reduction is required. Herein, we recapitulate recent findings, clinical applications, and ASCVD prevention potential of PCSK9 inhibition, with focus on anti-PCSK9 monoclonal antibodies, evolocumab and alirocumab.

STAT3 and Endothelial Cell-Cardiomyocyte Dialog in Cardiac Remodeling

This article presents an overview of the central role of STAT3 in the crosstalk between endothelial cells and cardiac myocytes in the heart. Endothelial cell STAT3 has a key role in inflammation that underlies cardiovascular disease and impacts on cardiac structure and function. STAT3 in endothelial cells contributes to adverse cardiomyocyte genetic reprograming, for instance, during peripartum cardiomyopathy. Conversely, cardiomyocyte STAT3 is important for maintaining endothelial cell function and capillary integrity with aging and hypertension. In addition, STAT3 serves as a sentinel for stress in the heart. Recent evidence has revealed that the redox nature of STAT3 is regulated, and STAT3 is responsive to oxidative stress (ischemia-reperfusion) so as to induce protective genes. At the level of the mitochondrion, STAT3 is important in regulating reactive oxygen species (ROS) formation, metabolism, and mitochondrial integrity. STAT3 may also control calcium release from the ER so as to limit its subsequent uptake by mitochondria and the induction of cell death. Under normal conditions, some STAT3 localizes to intercalated discs of cardiomyocytes and serves to transmit pro-fibrotic gene induction signals in the nucleus with increased blood pressure. Further research is needed to understand how the sentinel role of STAT3 in both endothelial cells and cardiomyocytes is integrated in order to coordinate the response of the heart to both physiological and pathological demands.