Chronic Inflammation & Inflammaging Research

Summary

Inflammaging describes the low-grade, sterile, chronic inflammation that develops with age in the absence of infection. It is one of the most consistent predictors of mortality and functional decline in human cohort studies, and it links several other hallmarks of ageing together.

Last reviewed 2026-09-01

What it is

Inflammaging is a chronic, low-grade, systemic pro-inflammatory state characterised by modestly elevated circulating IL-6, TNF-α and C-reactive protein in the absence of overt infection.

The term was introduced by Claudio Franceschi in 2000, drawing on observations that inflammatory markers predicted frailty and mortality in elderly cohorts better than most other measures.

Not a single source — contributors include senescent cell secretions, mitochondrial DNA released into the cytosol, gut barrier permeability, visceral adipose tissue and accumulated antigenic load.

IL-6 and CRP are inexpensive, standardised and predictive, making inflammaging one of the few ageing processes measurable in routine clinical practice.

How it works

In plain terms

Instead of flaring up and resolving, the immune system stays slightly switched on all the time. That constant background signal damages tissue slowly and interferes with repair.

Technical detail

Multiple upstream sources converge on NF-κB and inflammasome activation. Senescent cells secrete the SASP, a cocktail of IL-6, IL-8, matrix metalloproteinases and growth factors. Mitochondrial DNA escaping into the cytosol activates cGAS-STING as a damage-associated molecular pattern. Increased intestinal permeability allows lipopolysaccharide translocation, engaging TLR4. Visceral adipose tissue macrophages shift toward a pro-inflammatory phenotype. The resulting IL-6 elevation drives hepatic CRP production and contributes to muscle protein breakdown, insulin resistance and endothelial dysfunction.

Pathways involved

NF-κB and NLRP3 inflammasome activation
Senescence-associated secretory phenotype (SASP)
cGAS-STING activation by cytosolic mtDNA
TLR4 engagement by translocated LPS
Adipose tissue macrophage polarisation

Current research

Laboratory research

SASP composition and inflammasome activation are well characterised in cell models; senolytic clearance reduces SASP output in vitro.

Animal research

Senolytic treatment reduces inflammatory markers and improves physical function in aged mice. Germ-free and microbiome transplant experiments demonstrate a gut contribution.

Human research

Large cohort studies including InCHIANTI, the Health ABC study and the Framingham cohort consistently show IL-6 and CRP predicting mortality, frailty and disability. Interventional evidence is thinner: CANTOS demonstrated that IL-1β inhibition with canakinumab reduced cardiovascular events independently of lipid lowering, providing rare causal support that inflammation itself is a driver rather than only a marker. Exercise, weight reduction and improved sleep reduce inflammatory markers reliably in trials.

Ongoing research

Senolytics, IL-6 pathway inhibitors and microbiome interventions are the main clinical directions.

What is being investigated

IL-6 and CRP as predictors of frailty and mortality
Senescent cell clearance to reduce SASP burden
Gut permeability and microbiome contributions
Exercise, sleep and diet as inflammatory modifiers
Targeted cytokine inhibition (IL-1β, IL-6)

These are research directions reported in the literature, not established effects or recommendations.

Risks, limitations and unknowns

Read this section before the rest

Inflammation is protective as well as damaging; broad suppression increases infection risk, as seen in CANTOS
CRP and IL-6 are non-specific and fluctuate with acute illness, making single measurements unreliable
Most observational associations cannot separate cause from consequence
Anti-inflammatory supplements are widely marketed with weak or surrogate-only evidence
Lowering a biomarker does not automatically improve outcomes

Evidence ratings

Laboratory studies

Strong

SASP and inflammasome biology well established.

Animal studies

Strong

Senolytic and microbiome interventions reproducible.

Human observational

Strong

Consistent mortality prediction across large cohorts.

Human interventional

Moderate

CANTOS provides causal support; broader trials limited.

References

[1]Inflammaging reviews — PubMed, 2000–present
[2]IL-6 and mortality in ageing cohorts — PubMed, 1999–present
[3]CANTOS trial — PubMed / NEJM, 2017
Reference links open searches and records on PubMed and ClinicalTrials.gov so that every statement above can be traced to primary literature.

Frequently asked questions

What is inflammaging?+

Chronic, low-grade, sterile inflammation that develops with age and predicts frailty, disability and mortality in cohort studies.

Which markers indicate chronic inflammation?+

Most commonly high-sensitivity CRP, IL-6 and TNF-α. IL-6 has the strongest association with functional decline.

What causes inflammaging?+

Multiple sources: senescent cell secretions, cytosolic mitochondrial DNA, gut permeability, visceral fat and accumulated antigen exposure.

Did CANTOS prove inflammation causes heart disease?+

It provided strong causal support — IL-1β inhibition reduced cardiovascular events without changing lipids — while also increasing fatal infections.

Can exercise lower inflammation?+

Yes. Regular exercise reliably reduces CRP and IL-6 in trials, though acute exercise transiently raises them.

Is all inflammation bad?+

No. Acute inflammation is essential for defence and repair. The problem is the chronic, unresolved, low-grade form.

Do anti-inflammatory supplements help?+

Most have surrogate-marker evidence at best. Reducing a marker is not equivalent to improving health outcomes.

What is the SASP?+

The senescence-associated secretory phenotype — the inflammatory factors secreted by senescent cells that spread dysfunction to neighbouring tissue.

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