title: Patterns of circulating inflammatory biomarkers in older persons with varying levels of physical performance: a partial least squares-discriminant analysis approach.
abstract: BACKGROUND
  Chronic, low-grade inflammation and declining physical function are hallmarks of the aging process. However, previous attempts to correlate individual inflammatory biomarkers with physical performance in older people have produced mixed results. Given the complexity of the inflammatory response, the simultaneous analysis of an array of inflammatory mediators may provide more insights into the relationship between inflammation and age-related physical function decline. This study was designed to explore the association between a panel of inflammatory markers and physical performance in older adults through a multivariate statistical approach.
  
  
  METHODS
  Community-dwelling older persons were categorized into "normal walkers" (NWs; n = 27) or "slow walkers" (SWs; n = 11) groups using 0.8 m s(-1) as the 4-m gait speed cutoff. A panel of 14 circulating inflammatory biomarkers was assayed by multiplex analysis. Partial least squares-discriminant analysis (PLS-DA) was used to identify patterns of inflammatory mediators associated with gait speed categories.
  
  
  RESULTS
  The optimal complexity of the PLS-DA model was found to be five latent variables. The proportion of correct classification was 88.9% for NW subjects (74.1% in cross-validation) and 90.9% for SW individuals (81.8% in cross-validation). Discriminant biomarkers in the model were interleukin 8, myeloperoxidase, and tumor necrosis factor alpha (all higher in the SW group), and P-selectin, interferon gamma, and granulocyte-macrophage colony-stimulating factor (all higher in the NW group).
  
  
  CONCLUSIONS
  Distinct profiles of circulating inflammatory biomarkers characterize older subjects with different levels of physical performance. The dissection of these patterns may provide novel insights into the role played by inflammation in the disabling cascade and possible new targets for interventions.
authors.affiliation: Department of Geriatrics, Neurosciences and Orthopedics, Catholic University of the Sacred Heart , Rome , Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Marzetti
authors.affiliation: Department of Geriatrics, Neurosciences and Orthopedics, Catholic University of the Sacred Heart , Rome , Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Landi
authors.affiliation: Department of Chemistry, Sapienza University of Rome , Rome , Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Marini
authors.affiliation: Gérontopôle, Centre Hospitalier Universitaire de Toulouse , Toulouse , France ; INSERM UMR1027, Université de Toulouse III Paul Sabatier , Toulouse , France.
authors.forename: Matteo
authors.initials: M
authors.lastname: Cesari
authors.affiliation: Department of Aging and Geriatric Research, University of Florida , Gainesville, FL , USA.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Buford
authors.affiliation: Department of Aging and Geriatric Research, University of Florida , Gainesville, FL , USA.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Manini
authors.affiliation: Department of Geriatrics, Neurosciences and Orthopedics, Catholic University of the Sacred Heart , Rome , Italy.
authors.forename: Graziano
authors.initials: G
authors.lastname: Onder
authors.affiliation: Department of Aging and Geriatric Research, University of Florida , Gainesville, FL , USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Pahor
authors.affiliation: Department of Geriatrics, Neurosciences and Orthopedics, Catholic University of the Sacred Heart , Rome , Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bernabei
authors.affiliation: Department of Aging and Geriatric Research, University of Florida , Gainesville, FL , USA.
authors.forename: Christiaan
authors.initials: C
authors.lastname: Leeuwenburgh
authors.affiliation: Department of Geriatrics, Neurosciences and Orthopedics, Catholic University of the Sacred Heart , Rome , Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Calvani
keywords: aging; cytokines; disability; gait speed; immune senescence; inflammaging; interleukin; multiplex assay