In short
Inflammaging is a state of chronic, low-grade, systemic inflammation that develops with advancing age, in the absence of overt infection, and is associated with most major age-related diseases.
The term was coined by Claudio Franceschi in 2000 to describe a pattern seen consistently in older adults: modestly but persistently elevated inflammatory markers like IL-6, TNF-alpha, and C-reactive protein, without any acute infection driving them. This differs from acute inflammation, which is a short, purposeful immune response to injury or infection that resolves once the threat is cleared.
Several of the hallmarks of aging feed into inflammaging: senescent cells secrete inflammatory factors through the SASP (senescence-associated secretory phenotype), immune system aging (immunosenescence) makes the immune response both less effective and more prone to low-grade activation, gut barrier changes can let bacterial products leak into circulation, and visceral fat is itself a source of inflammatory signaling.
Inflammaging is strongly associated in epidemiological studies with cardiovascular disease, type 2 diabetes, frailty, sarcopenia, and cognitive decline, and elevated hs-CRP is one of the most widely used clinical markers for it. However, association in observational data is not the same as a proven causal driver for any single disease — inflammaging is best understood as a marker of and probable contributor to the broader burden of age-related disease, alongside the other hallmarks, rather than a single treatable condition on its own.