title: Using cluster analysis of cytokines to identify patterns of inflammation in hospitalized patients with community-acquired pneumonia: a pilot study.
abstract: BACKGROUND
  Patients with severe community-acquired pneumonia (CAP) are believed to have an exaggerated inflammatory response to bacterial infection. Therapies aiming to modulate the inflammatory response have been largely unsuccessful, perhaps reflecting that CAP is a heterogeneous disorder that cannot be modulated by a single anti-inflammatory approach. We hypothesize that the host inflammatory response to pneumonia may be characterized by distinct cytokine patterns, which can be harnessed for personalized therapies.
  
  
  METHODS
  Here, we use hierarchical cluster analysis of cytokines to examine if patterns of inflammatory response in 13 hospitalized patients with CAP can be defined. This was a secondary data analysis of the Community-Acquired Pneumonia Inflammatory Study Group (CAPISG) database. The following cytokines were measured in plasma and sputum on the day of admission: interleukin (IL)-1β, IL-1 receptor antagonist (IL-1ra), IL-6, CXCL8 (IL-8), IL-10, IL-12p40, IL-17, interferon (IFN)γ, tumor necrosis factor (TNF)α, and CXCL10 (IP-10). Hierarchical agglomerative clustering algorithms were used to evaluate clusters of patients within plasma and sputum cytokine determinations.
  
  
  RESULTS
  A total of thirteen patients were included in this pilot study. Cluster analysis identified distinct inflammatory response patterns of cytokines in the plasma, sputum, and the ratio of plasma to sputum.
  
  
  CONCLUSIONS
  Inflammatory response patterns in plasma and sputum can be identified in hospitalized patients with CAP. Characterization of the local and systemic inflammatory response may help to better discriminate patients for enrollment into clinical trials of immunomodulatory therapies.
authors.affiliation: University of Louisville Division of Infectious Diseases, Louisville, Kentucky, USA.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Wiemken
authors.affiliation: University of Louisville Division of Infectious Diseases, Louisville, Kentucky, USA.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Kelley
authors.affiliation: University of Louisville Department of Pathology and Laboratory Medicine, Louisville, Kentucky, USA.
authors.forename: Rafael
authors.initials: R
authors.lastname: Fernandez-Botran
authors.affiliation: University of Louisville Division of Infectious Diseases, Louisville, Kentucky, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Mattingly
authors.affiliation: University of Louisville Division of Infectious Diseases, Louisville, Kentucky, USA.
authors.forename: Forest W
authors.initials: FW
authors.lastname: Arnold
authors.affiliation: University of Louisville Division of Infectious Diseases, Louisville, Kentucky, USA.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Furmanek
authors.affiliation: Department of Pulmonary Diseases, South Texas Veterans Health Care System and University of Texas at San Antonio, San Antonio, Texas, USA.
authors.forename: Marcos I
authors.initials: MI
authors.lastname: Restrepo
authors.affiliation: Department of Respiratory Medicine, Ninewells Hospital and Medical School, Dundee, United Kingdom.
authors.forename: James D
authors.initials: JD
authors.lastname: Chalmers
authors.affiliation: University of Louisville Division of Infectious Diseases, Louisville, Kentucky, USA.
authors.forename: Paula
authors.initials: P
authors.lastname: Peyrani
authors.affiliation: University of Louisville Division of Pulmonary, Critical Care, and Sleep Disorders Medicine, Louisville, Kentucky USA.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Cavallazzi
authors.affiliation: Providence Hospital Section of Infectious Diseases, Washington DC, USA.
authors.forename: Jose
authors.initials: J
authors.lastname: Bordon
authors.affiliation: Department of Health Sciences, University of Milano - Bicocca, Respiratory Unit, AO San Gerardo, Monza, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Aliberti
authors.affiliation: University of Louisville Division of Infectious Diseases, Louisville, Kentucky, USA.
authors.forename: Julio A
authors.initials: JA
authors.lastname: Ramirez
keywords: Cytokines; immunomodulation; inflammatory response; outcomes; pneumonia; steroids