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A pinboard by
Marissa Fahlberg

Inflammation is the hallmark of aging, and I want to know why.

PINBOARD SUMMARY

The hallmark of aging is inflammation. Figuring out why - and how to slow it - is the challenge.

In 10 seconds? Scientists don’t know exactly why we age, but a critical factor in determining “biological age” and life expectancy is the degree of inflammation your body has.

What is biological age? Distinct from chronological age, which is marked by how many birthdays you’ve had, biological age is a measure of a person’s overall health that determines their chances of developing age-related diseases and predicts expected lifespan.

How do we determine biological age? Researchers have been able to calculate biological age by measuring exposure to factors such as smoking and drinking alcohol, the level of certain proteins circulating in the blood (inflammation), and how the function of DNA is modified (epigenetics).

How is inflammation related to biological age? Inflammation is consistently observed in elderly adults, so much so that some scientists have changed the term ‘aging’ to ‘inflammaging’. The degree of inflammation corresponds closely with the risk of developing diseases including heart attacks, diabetes, stroke, kidney function, and many other diseases that generally occur in older people.

What, exactly, is inflammation? Several different proteins circulate in our blood at all times. A certain class of proteins, called cytokines, are secreted by immune cells in response to infection or organ damage, and the term ‘inflammation’ is characterized by an increase of circulating cytokines. An increase of these cytokines after infection or organ damage is called 'acute' inflammation. ‘Chronic’ inflammation, which occurs during aging, is characterized by a modest increase of these cytokines in the absence of infection or organ damage. This increase of cytokines is continuous and does not go away, and researchers measure these cytokines to determine the degree of chronic inflammation.

Where does chronic inflammation come from? In short: we don’t know. We do know that certain immune cells constantly express low levels of inflammatory cytokines for no obvious reason in aging adults. In addition, certain viruses cannot be cured, including herpes and cytomegalovirus (CMV). It is thought that these viruses constantly replicate at low-levels and push the immune system to respond, and part of this response is secretion of inflammatory cytokines.

Do anti-inflammatory diets really help? Evidence suggests that foods such as green tea and leafy vegetables reduce and delay chronic inflammation in humans and model systems. Drink up!

43 ITEMS PINNED

Chronic inflammation as a determinant of future aging phenotypes.

Abstract: The importance of chronic inflammation as a determinant of aging phenotypes may have been underestimated in previous studies that used a single measurement of inflammatory markers. We assessed inflammatory markers twice over a 5-year exposure period to examine the association between chronic inflammation and future aging phenotypes in a large population of men and women.We obtained data for 3044 middle-aged adults (28.2% women) who were participating in the Whitehall II study and had no history of stroke, myocardial infarction or cancer at our study's baseline (1997-1999). Interleukin-6 was measured at baseline and 5 years earlier. Cause-specific mortality, chronic disease and functioning were ascertained from hospital data, register linkage and clinical examinations. We used these data to create 4 aging phenotypes at the 10-year follow-up (2007-2009): successful aging (free of major chronic disease and with optimal physical, mental and cognitive functioning), incident fatal or nonfatal cardiovascular disease, death from noncardiovascular causes and normal aging (all other participants).Of the 3044 participants, 721 (23.7%) met the criteria for successful aging at the 10-year follow-up, 321 (10.6%) had cardiovascular disease events, 147 (4.8%) died from noncardiovascular causes, and the remaining 1855 (60.9%) were included in the normal aging phenotype. After adjustment for potential confounders, having a high interleukin-6 level (> 2.0 ng/L) twice over the 5-year exposure period nearly halved the odds of successful aging at the 10-year follow-up (odds ratio [OR] 0.53, 95% confidence interval [CI] 0.38-0.74) and increased the risk of future cardiovascular events (OR 1.64, 95% CI 1.15-2.33) and noncardiovascular death (OR 2.43, 95% CI 1.58-3.80).Chronic inflammation, as ascertained by repeat measurements, was associated with a range of unhealthy aging phenotypes and a decreased likelihood of successful aging. Our results suggest that assessing long-term chronic inflammation by repeat measurement of interleukin-6 has the potential to guide clinical practice.

Pub.: 18 Sep '13, Pinned: 16 Apr '17

Aerobic exercise reverses arterial inflammation with aging in mice.

Abstract: We tested the hypothesis that regular aerobic exercise reverses arterial inflammation with aging. When compared with young controls (6.2 ± 0.4 mo; n = 7), old (31.3 ± 0.5 mo; n = 11) male B6D2F1 cage-restricted mice demonstrated increased arterial activation of the proinflammatory transcription factor NF-κB, as indicated by greater aortic phosphorylation of both the inhibitor of NF-κB kinase (IKK) and the p65 subunit of NF-κB (both P < 0.05). Similarly, aortic expression of the proinflammatory cytokines IL-1 and IL-6, IFN-γ, and TNF-α were greater in the old mice (all P < 0.05). Macrophage and T lymphocyte abundance was unchanged with age in the aortic intima and media but was markedly increased in the adventitia and perivascular fat tissue of old mice (all P < 0.05). This proinflammatory arterial phenotype with aging was associated with vascular dysfunction, as reflected by impaired nitric oxide-mediated endothelium-dependent dilation. Voluntary wheel running (10-14 wk) normalized aortic IKK-NF-κB activation, cytokine expression, adventitial and perivascular macrophage infiltration, and vascular function in old mice (32.4 ± 0.3 mo; n = 8) while having no consistent effects in young mice. Short-term voluntary wheel running started late in life reverses arterial inflammation with aging in mice possibly via outside-in actions. These anti-inflammatory effects may play an important role in the amelioration of age-associated vascular dysfunction by regular aerobic exercise.

Pub.: 31 May '11, Pinned: 16 Apr '17

Energy Metabolism and Inflammation in Brain Aging and Alzheimer’s Disease

Abstract: The high energy demand of the brain renders it sensitive to changes in energy fuel supply and mitochondrial function. Deficits in glucose availability and mitochondrial function are well-known hallmarks of brain aging and are particularly accentuated in neurodegenerative disorders such as Alzheimer’s disease. As important cellular sources of H2O2, mitochondrial dysfunction is usually associated with altered redox status. Bioenergetic deficits and chronic oxidative stress are both major contributors to cognitive decline associated with brain aging and Alzheimer’s disease. Neuroinflammatory changes, including microglial activation and production of inflammatory cytokines, are observed in neurodegenerative diseases and normal aging. The bioenergetic hypothesis advocates for sequential events from metabolic deficits to propagation of neuronal dysfunction, to aging, and to neurodegeneration, while the inflammatory hypothesis supports microglia activation as the driving force for neuroinflammation. Nevertheless, growing evidence suggests that these diverse mechanisms have redox dysregulation as a common denominator and connector. An independent view of the mechanisms underlying brain aging and neurodegeneration is being replaced by one that entails multiple mechanisms coordinating and interacting with each other. This review focuses on the alterations in energy metabolism and inflammatory responses and their connection via redox regulation in normal brain aging and Alzheimer’s disease. Interactions of these systems is reviewed based on basic research and clinical studies.

Pub.: 03 May '16, Pinned: 16 Apr '17

Para-inflammation in the aging retina.

Abstract: Para-inflammation is a tissue adaptive response to noxious stress or malfunction and has characteristics that are intermediate between basal and inflammatory states (Medzhitov, 2008). The physiological purpose of para-inflammation is to restore tissue functionality and homeostasis. Para-inflammation may become chronic or turn into inflammation if tissue stress or malfunction persists for a sustained period. Chronic para-inflammation contributes to the initiation and progression of many human diseases including obesity, type 2 diabetes, atherosclerosis, and age-related neurodegenerative diseases. Evidence from our studies and the studies of some others suggests that para-inflammation also exists in the aging retina in physiological conditions and might contribute to age-related retinal pathologies. The purpose of this review is to introduce the notion of "para-inflammation" as a state between frank, overt destructive inflammation and the non-inflammatory removal of dead or dying cells by apoptosis, to the retinal community. In diabetes and atherosclerosis, leukocytes particularly monocytes and vascular endothelial cells are constantly under noxious stress due to glycaemic and/or lipidaemic dysregulation. These blood-borne stresses trigger para-inflammatory responses in leukocytes and endothelial cells by up-regulating the expression of adhesion molecules or releasing cytokines/chemokines, which in turn cause abnormal leukocyte-endothelial interactions and ultimately vascular damage. In the aging retina, on the other hand, oxidized lipoproteins and free radicals are considered to be major causes of tissue stress and serve as local triggers for retinal para-inflammation. Microarray analysis has revealed the up-regulation of a large number of inflammatory genes, including genes involved in complement activation and inflammatory cytokine/chemokine production, in the aging retina. Para-inflammatory responses in the neuroretina of aged mice are characterized by microglial activation and subretinal migration, and breakdown of blood-retinal barrier. At the retinal/choroidal interface para-inflammation is manifested by complement activation in Bruch's membrane and RPE cells, and microglia accumulation in subretinal space. With age, para-inflammatory changes have also been observed in the choroidal tissue, evidenced by 1) increased thickness of choroid; 2) increased number of CD45(+)CRIg(+) macrophages; 3) morphological abnormalities in choroidal melanocytes; and 4) fibrosis in choroidal tissue. An increased knowledge of contribution of retinal para-inflammation to various pathological conditions is essential for the better understanding of the pathogenesis of various age-related retinal diseases including diabetic retinopathy, glaucoma and age-related macular degeneration.

Pub.: 30 Jun '09, Pinned: 16 Apr '17

Inflammation and the degenerative diseases of aging.

Abstract: Chronic inflammation is associated with a broad spectrum of neurodegenerative diseases of aging. Included are such disorders as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis, the Parkinson-dementia complex of Guam, all of the tauopathies, and age-related macular degeneration. Also included are such peripheral conditions as osteoarthritis, rheumatoid arthritis, atherosclerosis, and myocardial infarction. Inflammation is a two-edged sword. In acute situations, or at low levels, it deals with the abnormality and promotes healing. When chronically sustained at high levels, it can seriously damage viable host tissue. We describe this latter phenomenon as autotoxicity to distinguish it from autoimmunity. The latter involves a lymphocyte-directed attack against self proteins. Autotoxicity, on the other hand, is determined by the concentration and degree of activation of tissue-based monocytic phagocytes. Microglial cells are the brain representatives of the monocyte phagocytic system. Biochemically, the intensity of their activation is related to a spectrum of inflammatory mediators generated by a variety of local cells. The known spectrum includes, but is not limited to, prostaglandins, pentraxins, complement components, anaphylotoxins, cytokines, chemokines, proteases, protease inhibitors, adhesion molecules, and free radicals. This spectrum offers a huge variety of targets for new anti-inflammatory agents. It has been suggested, largely on the basis of transgenic mouse models, that stimulating inflammation rather than inhibiting it can be beneficial in such diseases as AD. If this were the case, administration of NSAIDs, or other anti-inflammatory drugs, would be expected to exacerbate conditions such as AD, PD, and atherosclerosis. However, epidemiological evidence overwhelmingly demonstrates that the reverse is true. This indicates that, at least in these diseases, the inflammation is harmful. So far, advantage has not been taken of opportunities indicated by these epidemiological studies to treat AD and PD with appropriate anti-inflammatory agents. Based on this evidence, classical NSAIDs are the most logical choice. Dosage, though, must be sufficient to combat the inflammation. Analysis of mRNA levels of inflammatory mediators indicates that the intensity of inflammation is considerably higher in AD hippocampus and in PD substantia nigra than in osteoarthritic joints. Thus, full therapeutic doses of NSAIDs, or combinations of anti-inflammatory agents, are needed to achieve the suggested neurological benefits.

Pub.: 01 Feb '05, Pinned: 16 Apr '17

Oxidative stress and vascular inflammation in aging.

Abstract: Vascular aging, a determinant factor for cardiovascular disease and health status in the elderly, is now viewed as a modifiable risk factor. Impaired endothelial vasodilation is a early hallmark of arterial aging that precedes the clinical manifestations of vascular dysfunction, the first step to cardiovascular disease and influencing vascular outcomes in the elderly. Accordingly, the preservation of endothelial function is thought to be an essential determinant of healthy aging. With special attention on the effects of aging on the endothelial function, this review is focused on the two main mechanisms of aging-related endothelial dysfunction: oxidative stress and inflammation. Aging vasculature generates an excess of the reactive oxygen species (ROS), superoxide and hydrogen peroxide, that compromise the vasodilatory activity of nitric oxide (NO) and facilitate the formation of the deleterious radical, peroxynitrite. Main sources of ROS are mitochondrial respiratory chain and NADPH oxidases, although NOS uncoupling could also account for ROS generation. In addition, reduced antioxidant response mediated by erythroid-2-related factor-2 (Nrf2) and downregulation of mitochondrial manganese superoxide dismutase (SOD2) contributes to the establishment of chronic oxidative stress in aged vessels. This is accompanied by a chronic low-grade inflammatory phenotype that participates in defective endothelial vasodilation. The redox-sensitive transcription factor, nuclear factor-κB (NF-κB), is upregulated in vascular cells from old subjects and drives a proinflammatory shift that feedbacks oxidative stress. This chronic NF-κB activation is contributed by increased angiotensin-II signaling and downregulated sirtuins and precludes adequate cellular response to acute ROS generation. Interventions targeted to recover endogenous antioxidant capacity and cellular stress response rather than exogenous antioxidants could reverse oxidative stress-inflammation vicious cycle in vascular aging. Lifestyle attitudes such as caloric restriction and exercise training appear as effective ways to overcome defective antioxidant response and inflammation, favoring successful vascular aging and decreasing the risk for cardiovascular disease.

Pub.: 16 Jul '13, Pinned: 16 Apr '17

Molecular mechanisms of aging-associated inflammation.

Abstract: A direct relationship exists between aging and increasing incidences of chronic diseases. In fact, with most age-associated diseases individuals manifest an underlying chronic inflammatory state as evidenced by local infiltration of inflammatory cells, such as macrophages, and higher circulatory levels of pro-inflammatory cytokines, complement components and adhesion molecules. Consequently, treatment with anti-inflammatory agents provide symptomatic relief to several aging-associated diseases, even as remote as Alzheimer's or Parkinson's disease, indicating that chronic inflammation may play a substantial role in the pathogenesis of these disease states. The molecular mechanisms underlying this chronic inflammatory condition during cellular senescence is presently unclear. Cellular damage by oxygen free radicals is a primary driving force for aging and increased activation of redox-regulated transcription factors, such as NF-kappaB that regulate the expression of pro-inflammatory molecules, has been documented in aged animals/individuals versus their young counterparts. Human polynucleotide phosphorylase (hPNPase(old-35)), a RNA degradation enzyme shown to be upregulated during differentiation and cellular senescence, may represent a molecular link between aging and its associated inflammation. hPNPase(old-35) promotes reactive oxygen species (ROS) production, activates the NF-kappaB pathway and initiates the production of pro-inflammatory cytokines, such as IL-6 and IL-8. In these contexts, inhibition of hPNPase(old-35) may represent a novel molecular target for intervening in aging-associated chronic diseases.

Pub.: 28 Jun '05, Pinned: 16 Apr '17

Aging-related inflammation in osteoarthritis.

Abstract: It is well accepted that aging is an important contributing factor to the development of osteoarthritis (OA). The mechanisms responsible appear to be multifactorial and may include an age-related pro-inflammatory state that has been termed "inflamm-aging." Age-related inflammation can be both systemic and local. Systemic inflammation can be promoted by aging changes in adipose tissue that result in increased production of cytokines such as interleukin (IL)-6 and tumor necrosis factor-α (TNFα). Numerous studies have shown an age-related increase in blood levels of IL-6 that has been associated with decreased physical function and frailty. Importantly, higher levels of IL-6 have been associated with an increased risk of knee OA progression. However, knockout of IL-6 in male mice resulted in worse age-related OA rather than less OA. Joint tissue cells, including chondrocytes and meniscal cells, as well as the neighboring infrapatellar fat in the knee joint, can be a local source of inflammatory mediators that increase with age and contribute to OA. An increased production of pro-inflammatory mediators that include cytokines and chemokines, as well as matrix-degrading enzymes important in joint tissue destruction, can be the result of cell senescence and the development of the senescence-associated secretory phenotype (SASP). Further studies are needed to better understand the basis for inflamm-aging and its role in OA with the hope that this work will lead to new interventions targeting inflammation to reduce not only joint tissue destruction but also pain and disability in older adults with OA.

Pub.: 03 Nov '15, Pinned: 16 Apr '17