Cited by 594Genetics, Aging, and Longevity in Model OrganismsTelomeres, Telomerase, and SenescenceFrailty in Older Adults

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An inflammatory aging clock (iAge) based on deep learning tracks multimorbidity, immunosenescence, frailty and cardiovascular aging

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Abstract

While many diseases of aging have been linked to the immunological system, immune metrics capable of identifying the most at-risk individuals are lacking. From the blood immunome of 1,001 individuals aged 8–96 years, we developed a deep-learning method based on patterns of systemic age-related inflammation. The resulting inflammatory clock of aging (iAge) tracked with multimorbidity, immunosenescence, frailty and cardiovascular aging, and is also associated with exceptional longevity in centenarians. The strongest contributor to iAge was the chemokine CXCL9, which was involved in cardiac aging, adverse cardiac remodeling and poor vascular function. Furthermore, aging endothelial cells in human and mice show loss of function, cellular senescence and hallmark phenotypes of arterial stiffness, all of which are reversed by silencing CXCL9. In conclusion, we identify a key role of CXCL9 in age-related chronic inflammation and derive a metric for multimorbidity that can be utilized for the early detection of age-related clinical phenotypes. From the blood immunome of 1,001 individuals aged 8–96 years, the authors used deep learning to develop an inflammatory clock of aging (iAge) that tracks with multimorbidity, immunosenescence, frailty and cardiovascular aging, and is also associated with exceptional longevity in centenarians. The main contributor to iAge is the chemokine CXCL9, which is shown to control endothelial cell senescence and function.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

Using blood immune protein data from 1,001 people aged 8–96, the authors built a deep-learning inflammatory aging clock (iAge) that predicts chronological age and tracks multimorbidity, frailty, immunosenescence, and cardiovascular aging. CXCL9 emerged as the strongest positive contributor, and silencing it reversed endothelial dysfunction and senescence phenotypes in human and mouse models.

Key findings

  • iAge correlated with chronological age at R = 0.78 (P < 10−16); the guided auto-encoder outperformed linear methods (P < 0.05) except a classic neural network (P = 0.54), with average test reconstruction errors of 15.2 years for age and 0.26 normalized for protein data.
  • iAge was associated with multimorbidity in adults over 60 (n = 285, P < 0.01); Elastic Net prediction of multimorbidity had MAE = 0.41, with iAge, high cholesterol, and BMI among the largest coefficients. In 29 older adults, iAge in 2010 predicted 2017 frailty score (R² = 0.81, P < 0.001), stronger than calendar age. Among 19 centenarians and 18 controls, 13/19 centenarians were in the low iAge-index group (P = 0.028), and the iAge gene signature was associated with all-cause mortality in Framingham (P = 0.02, n = 2,290).
  • iAge correlated with immunosenescence markers: naive CD8+ T-cell frequency and phospho-STAT responses across 818 individuals and 96 conditions (combined P < 10−5).
  • CXCL9 was the top positive iAge contributor and rose with age (P < 10−15, starting around age 60). In 97 healthy adults aged 25–90, CXCL9 correlated with pulse wave velocity (R = 0.22) and relative wall thickness (R = 0.3) at P < 0.01, while LIF correlated negatively (R = −0.27 and −0.22). CXCL9 knockdown (~75% reduction) rescued tube formation, nitric oxide production, and Ac-LDL uptake in late-passage iPSC-ECs; RNA-seq showed ~fourfold CXCL9 increase at passage 8, inflammatory pathway upregulation, proliferation pathway downregulation, and reversal of arterial-stiffness-related CAM/MMP/COL gene changes.

Methods

  • The Stanford 1000 Immunomes Project enrolled 1,001 ambulatory participants (339 males, 662 females) aged 8–96 between 2007 and 2016; serum cytokines were measured in 1,001, CMV status in 748, gene expression in 397, cellular phenotypes in 935, in vitro cytokine stimulations in 818, and a 53-item clinical questionnaire in 902. Only healthy controls from the chronic fatigue syndrome study were used.
  • iAge was derived with a guided auto-encoder (GAE), a two-layer neural network balancing reconstruction and chronological-age prediction losses; fivefold cross-validation with nested threefold hyperparameter selection chose code length 5, depth 2, guidance ratio 0.2, and L2 = 0.001. Comparisons included Elastic Net, gradient boosting, PCA, plain auto-encoders, and neural networks.
  • Validation used 37 Italian centenarians/controls, a Framingham Heart Study gene-expression signature with Cox regression (n = 2,290), a 97-person cardiovascular cohort, human iPSC-derived endothelial cells, mouse aortic rings, RNA-seq, flow/CyTOF immunophenotyping, Luminex/SOMAscan assays, and isometric myography.

Limitations

  • The paper states that biological clocks generally do not directly reveal mechanism, so individual biomarkers require experimental testing; it also notes that the cytokine stimulation assay may not fully mirror in vivo stimuli and activates naive T cells and some helper T-cell subsets poorly. The authors also note that the iAge–chronological-age correlation (R = 0.78) is lower than a reported proteomic age metric (R = 0.92).
  • The paper states that no statistical method predetermined sample size, no data were excluded, and no randomization or blinding was used; mouse experiments were not blinded. The iAge model used cross-sectional baseline data even though some participants had longitudinal samples.
  • Evident from the text: several validation cohorts were modest in size (37 centenarian/control participants; 97 cardiovascular participants), and the Framingham analysis relied on a derived gene signature because sufficient proteomics data were unavailable, which may limit direct comparability and generalizability.

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Integrity signals

Registry

Crossref · 10.1038/s43587-021-00082-y

Cites

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86 Own result · 34 Own interpretation · 30 Own method · 22 Not checked yet · 3 No basis given · 2 Partly supported · accuracy not yet measured

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  • It may state two separate claims as one. 50
  • Probably not a substantial claim. 59
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94 of 94
  • The paper relies on this without support.

    The iAge gene expression signature derived from the Stanford cohort can serve as a proxy for iAge in the Framingham Heart Study cohort.

    “As there were no sufficient proteomics data to directly estimate iAge in the cohort, we derived a gene expression signature of iAge using available data from 397 participants in our study and performed an enrichment analysis of the derived gene signature on each sample in the Framingham Heart Study (Methods).”
  • The paper relies on this without support.

    CXCL9 attracts T cells, is induced by IFN-γ, and is primarily secreted by neutrophils, macrophages, and endothelial cells.

    “CXCL9 is a T-cell chemoattractant induced by IFN-γ and is mostly produced by neutrophils, macrophages and ECs.”
  • The paper relies on this without support.

    The Stanford 1KIP cohort reflects the general population for aging phenotypes.

    “This metric tracked with multiple aging phenotypes in the general population”
  • The paper relies on this without support.

    Chronological age serves as a valid benchmark for biological aging.

    “The correlation between chronological age and iAge was 0.78”
  • The paper relies on this without support.

    Auto-encoders can produce different results with different initialization (the re-parameterization problem).

    “One problem with auto-encoders is re-parameterization. With different initialization, it could have different results.”
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Metadata

Authors
Sayed, N., Huang, Y., Nguyen, K., Krejciova-Rajaniemi, Z., Grawe, A. P., Gao, T., Tibshirani, R., Hastie, T., Alpert, A., Cui, L., Kuznetsova, T., Rosenberg-Hasson, Y., Ostan, R., Monti, D., Lehallier, B., Shen-Orr, S. S., Maecker, H. T., Dekker, C. L., Wyss-Coray, T., Franceschi, C., Jojic, V., Haddad, F., Montoya, J. G., Wu, J. C., Davis, M. M., & Furman, D.
Affiliations
  • Stanford Medicine (US)
  • Buck Institute for Research on Aging (US)
  • University of North Carolina at Chapel Hill (US)
  • Technion – Israel Institute of Technology (IL)
  • KU Leuven (BE)
  • University of Bologna (IT)
  • University of Florence (IT)
  • N. I. Lobachevsky State University of Nizhny Novgorod (RU)
  • Howard Hughes Medical Institute (US)
Corresponding author
Furman, David
Venue
Nature Aging
Published
2021-07-12
Volume
1
Issue
7
Pages
598-615
ISSN
2662-8465 (ISSN-L)
OpenAlex
W3182997864
Cited by
572
References
124
Citations by year
2026: 118 · 2025: 117 · 2024: 159 · 2023: 86 · 2022: 71 · 2021: 21
FWCI
31.11
Type
journal article
Language
en
Open access
Locations
  • Nature Aging (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • Lirias (KU Leuven) (submittedVersion, other-oa)
  • Carolina Digital Repository (University of North Carolina at Chapel Hill) (submittedVersion)
  • Florence Research (University of Florence) (submittedVersion)
  • UNC Libraries
Funders
  • Glenn Foundation for Medical Research
  • European Commission
  • Ministry of Education and Science of the Russian Federation
  • National Institutes of Health (UL1TR003142)
  • National Institute on Aging (P50AG047366, P30AG059307, P30AG066515)
  • National Heart, Lung, and Blood Institute (K01HL135455)
  • National Institute of Allergy and Infectious Diseases (U19AI090019, U19AI057229)
  • National Institute of Diabetes and Digestive and Kidney Diseases (P30DK116074)
  • National Center for Research Resources (UL1RR025744)
  • National Center for Advancing Translational Sciences
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Aging › Genetics, Aging, and Longevity in Model Organisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Telomeres, Telomerase, and Senescence
  • Health Sciences › Medicine › Geriatrics and Gerontology › Frailty in Older Adults
Keywords
age-related inflammation, multimorbidity, immunosenescence, frailty, cardiovascular aging, centenarians, longevity, CXCL9, chemokines, endothelial cell senescence, arterial stiffness, cardiac remodeling, vascular function, deep learning
MeSH terms
Immunosenescence, Frailty, Multimorbidity, Deep Learning, Aged, 80 and over, Aging, Animals, Humans, Inflammation, Endothelial Cells, Mice

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