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categories: ["longevity"]categories: ["longevity"]tags: ["aging", "inflammation", "immunology", "senescence", "biomarkers", "mechanisms"]tags: ["aging", "inflammation", "immunology", "senescence", "biomarkers", "mechanisms"]summary: "The chronic, low-grade, sterile inflammation that develops with age in the absence of infection, and its disputed role in frailty and age-related disease."summary: "The chronic, low-grade, sterile inflammation that develops with age in the absence of infection, and its disputed role in frailty and age-related disease."updated: "2026-07-28"updated: "2026-10-29"humanEvidence: "Inflammatory markers rise with age in essentially every human population studied and predict mortality and frailty; the causal human evidence comes from cardiovascular trials of specific anti-inflammatory drugs, not from aging endpoints."humanEvidence: "Inflammatory markers rise with age in essentially every human population studied and predict mortality and frailty; the causal human evidence comes from cardiovascular trials of specific anti-inflammatory drugs, not from aging endpoints."issues: ["The colchicine cardiovascular trials are named but not cited.", "The IL-6 receptor genetic studies are described without a source."]issues: ["The colchicine cardiovascular trials are named but not cited.", "The IL-6 receptor genetic studies are described without a source."]------lines 30–36 → 30–3616 unchanged lines not shown
## The observation## The observation Inflammatory markers rise with age in essentially every population studied, and their level predicts outcomes. Interleukin-6 concentration in older adults is associated with subsequent disability, frailty, cognitive decline and all-cause mortality, robustly enough that it is sometimes described as the single most informative blood measure in geriatric epidemiology.[^ferrucci2018] Elevated C-reactive protein carries similar predictive weight for cardiovascular events.Inflammatory markers rise with age in essentially every population studied, and their level predicts outcomes. Interleukin-6 concentration in older adults is associated with subsequent disability, frailty, cognitive decline and all-cause mortality, consistently enough that it is sometimes described as the single most informative blood measure in geriatric epidemiology.[^ferrucci2018] Elevated C-reactive protein carries similar predictive weight for cardiovascular events. The elevation is small in absolute terms. It is chronic, not episodic; sterile, in that no pathogen is present; and heterogeneous, in that individuals of the same age differ widely. Some very old people show inflammatory profiles resembling those of middle-aged adults, and centenarian cohorts have been reported to combine high pro-inflammatory markers with high anti-inflammatory ones, which Franceschi interpreted as successful counter-regulation rather than absent inflammation.The elevation is small in absolute terms. It is chronic, not episodic; sterile, in that no pathogen is present; and heterogeneous, in that individuals of the same age differ widely. Some very old people show inflammatory profiles resembling those of middle-aged adults, and centenarian cohorts have been reported to combine high pro-inflammatory markers with high anti-inflammatory ones, which Franceschi interpreted as successful counter-regulation rather than absent inflammation. lines 44–65 → 44–657 unchanged lines not shown
**Retrotransposons.** LINE-1 elements, silenced by heterochromatin in young cells, become de-repressed in senescent and aged cells. Their reverse-transcribed cDNA is a cGAS substrate, and inhibiting reverse transcription reduces interferon signalling and age-associated inflammation in mice.[^dececco2019]**Retrotransposons.** LINE-1 elements, silenced by heterochromatin in young cells, become de-repressed in senescent and aged cells. Their reverse-transcribed cDNA is a cGAS substrate, and inhibiting reverse transcription reduces interferon signalling and age-associated inflammation in mice.[^dececco2019] **The gut.** Intestinal permeability increases with age in model organisms and, by indirect measures, in humans, allowing bacterial products such as lipopolysaccharide into the circulation. [[gut-microbiome|Microbiome]] composition shifts with age, though whether the shift causes inflammation or reflects it is unresolved — the same ambiguity that makes dysbiosis the least secure of the twelve hallmarks.**The gut.** Intestinal permeability increases with age in model organisms and, by indirect measures, in humans, allowing bacterial products such as lipopolysaccharide into the circulation. [[gut-microbiome|Microbiome]] composition shifts with age, though whether the shift causes inflammation or reflects it is unresolved, the same ambiguity that makes dysbiosis the least secure of the twelve hallmarks. **Immunosenescence.** The thymus involutes from childhood, shrinking the naive T-cell pool. Lifelong cytomegalovirus infection drives large expansions of memory T cells in most of the world's population. The remodelled immune system responds poorly to new antigens while maintaining chronic activation against old ones. Failing clearance of debris by aged macrophages compounds the effect, as does the clonal expansion of mutant blood stem cells described under [[stem-cell-exhaustion|stem cell exhaustion]].**Immunosenescence.** The thymus involutes from childhood, shrinking the naive T-cell pool. Lifelong cytomegalovirus infection drives large expansions of memory T cells in most of the world's population. The remodelled immune system responds poorly to new antigens while maintaining chronic activation against old ones. Failing clearance of debris by aged macrophages compounds the effect, as does the clonal expansion of mutant blood stem cells described under [[stem-cell-exhaustion|stem cell exhaustion]]. **Body composition and lifestyle.** Visceral adipose tissue is an endocrine organ that secretes IL-6 and recruits inflammatory macrophages, and adiposity increases with age in most populations. Physical inactivity, [[sleep-and-longevity|short or disrupted sleep]] and periodontal disease all raise inflammatory markers independently of age.**Body composition and lifestyle.** Visceral adipose tissue is an endocrine organ that secretes IL-6 and recruits inflammatory macrophages, and adiposity increases with age in most populations. Physical inactivity, [[sleep-and-longevity|short or disrupted sleep]] and periodontal disease all raise inflammatory markers independently of age. > [!debate] Cause or consequence> [!debate] Cause or consequence> The mechanistic case for inflammaging as a driver is strong in mice. In humans it rests largely on association, and inflammatory markers are downstream of nearly everything that goes wrong with an aging body. Sceptics argue that IL-6 is an excellent prognostic indicator precisely because it integrates many forms of damage, which is a different claim from saying that lowering it would help.> The mechanistic case for inflammaging as a driver is strong in mice. In humans it rests largely on association, and inflammatory markers are downstream of nearly everything that goes wrong with an aging body. Sceptics argue that IL-6 is an excellent prognostic indicator because it integrates many forms of damage, which is a different claim from saying that lowering it would help. ## Evidence that it is causal## Evidence that it is causal The best human evidence comes from cardiovascular medicine rather than from geroscience. Genetic studies of variants in the interleukin-6 receptor that mimic pharmacological blockade find lower coronary heart disease risk, supporting a causal role for IL-6 signalling in atherosclerosis. The CANTOS trial then tested this directly: canakinumab, an antibody against interleukin-1β, reduced recurrent cardiovascular events in patients with prior myocardial infarction and elevated CRP, without changing lipid levels.[^ridker2017] The same trial recorded an increase in fatal infection, which is the expected cost of suppressing innate immunity in an older population. Low-dose colchicine has since shown cardiovascular benefit in two large trials and has entered clinical use for that purpose.The best human evidence comes from cardiovascular medicine rather than from geroscience. Genetic studies of variants in the interleukin-6 receptor that mimic pharmacological blockade find lower coronary heart disease risk, supporting a causal role for IL-6 signalling in atherosclerosis. The CANTOS trial then tested this directly: canakinumab, an antibody against interleukin-1β, reduced recurrent cardiovascular events in patients with prior myocardial infarction and elevated CRP, without changing lipid levels.[^ridker2017] The same trial recorded an increase in fatal infection, which is the expected cost of suppressing innate immunity in an older population. Low-dose colchicine has since shown cardiovascular benefit in two large trials and has entered clinical use for that purpose. These results establish that a specific inflammatory pathway causes a specific age-related disease. They do not establish that inflammation drives aging in general. The counter-example is instructive: low-dose aspirin given to healthy older adults for primary prevention did not extend disability-free survival and increased major bleeding.[^mcneil2018] Broad anti-inflammatory prophylaxis in the well elderly has not been shown to help.These results establish that a specific inflammatory pathway causes a specific age-related disease. They do not establish that inflammation drives aging in general. Aspirin is the counter-example: given at low dose to healthy older adults for primary prevention, it did not extend disability-free survival and increased major bleeding.[^mcneil2018] Broad anti-inflammatory prophylaxis in the well elderly has not been shown to help. Animal work continues to produce larger effects than human work. Antibody blockade of interleukin-11 started in already-old mice extended median lifespan and improved several functional measures in a 2024 report — a substantial mouse result with no human counterpart, and one whose translation should be assumed uncertain until tested.[^widjaja2024]Animal work continues to produce larger effects than human work. Antibody blockade of interleukin-11 started in already-old mice extended median lifespan and improved several functional measures in a 2024 report, a substantial mouse result with no human counterpart, and one whose translation should be assumed uncertain until tested.[^widjaja2024] ## Measurement## Measurement lines 71–77 → 71–775 unchanged lines not shown
[[exercise-and-aging|Exercise]] lowers IL-6 and CRP modestly and reliably, and is the only intervention with strong human evidence on both inflammation and function. [[caloric-restriction|Caloric restriction]] lowers inflammatory markers in the human trials that have measured them. [[senolytics|Senolytic]] drugs reduce inflammatory markers in mice and in small uncontrolled human studies. [[rapamycin]] and [[metformin]] both have anti-inflammatory effects among their many actions.[[exercise-and-aging|Exercise]] lowers IL-6 and CRP modestly and reliably, and is the only intervention with strong human evidence on both inflammation and function. [[caloric-restriction|Caloric restriction]] lowers inflammatory markers in the human trials that have measured them. [[senolytics|Senolytic]] drugs reduce inflammatory markers in mice and in small uncontrolled human studies. [[rapamycin]] and [[metformin]] both have anti-inflammatory effects among their many actions. The design problem for all of them is that inflammation is not optional. It clears pathogens, resolves tissue damage, and supports repair; the CANTOS infection signal shows what happens when it is suppressed in an older population. Any intervention aimed at inflammaging must therefore target a specific source — senescent cells, cytosolic DNA sensing, a single cytokine — rather than inflammation as such. Which source dominates in an individual older human is, as of 2026, not measurable, and that is the practical obstacle to acting on the [[geroscience-hypothesis|geroscience]] version of the argument.The design problem for all of them is that inflammation is not optional. It clears pathogens, resolves tissue damage, and supports repair; the CANTOS infection signal shows what happens when it is suppressed in an older population. Any intervention aimed at inflammaging must therefore target a specific source (senescent cells, cytosolic DNA sensing, a single cytokine) rather than inflammation as such. Which source dominates in an individual older human is, as of 2026, not measurable, and that is the practical obstacle to acting on the [[geroscience-hypothesis|geroscience]] version of the argument. ## See also## See also removed, struck through added, underlinedLine numbers count the serialised markdown of each revision, frontmatter included.
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