title: Modulation of monocytes in septic patients: preserved phagocytic activity, increased ROS and NO generation, and decreased production of inflammatory cytokines.
abstract: BACKGROUND
  The nature of the inflammatory response underscoring the pathophysiology of sepsis has been extensively studied. We hypothesized that different cell functions would be differentially regulated in a patient with sepsis. We evaluated the modulation of monocyte functions during sepsis by simultaneously assessing their phagocytic activity, the generation of reactive oxygen species (ROS) and nitric oxide (NO), and the production of inflammatory cytokines (IL-6 and TNF-α).
  
  
  METHODS
  Whole blood was obtained from patients with severe sepsis and septic shock both at admission (D0, n = 34) and after seven days of therapy (D7, n = 15); 19 healthy volunteers were included as a control group. The cells were stimulated with LPS, Pseudomonas aeruginosa, and Staphylococcus aureus. The ROS and NO levels were quantified in monocytes in whole blood by measuring the oxidation of 2,7-dichlorofluorescein diacetate and 4-amino-5-methylamino-2,7-difluorofluorescein diacetate, respectively. Intracellular IL-6 and TNF-α were detected using fluorochrome-conjugated specific antibodies. Monocyte functions were also evaluated in CD163+ and CD163- monocyte subsets.
  
  
  RESULTS
  The monocytes from septic patients presented with preserved phagocytosis, enhanced ROS and NO generation, and decreased production of inflammatory cytokines compared with the monocytes from healthy volunteers. TNF-α and IL-6 increased and ROS generation decreased in D7 compared with D0 samples. In general, CD163+ monocytes produced higher amounts of IL-6 and TNF-α and lower amounts of ROS and NO than did CD163- monocytes.
  
  
  CONCLUSIONS
  We demonstrated that monocytes from septic patients, which are impaired to produce inflammatory cytokines, display potent phagocytic activity and increased ROS and NO generation.
authors.affiliation: Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, Sao Paulo, Brazil.
authors.forename: Sidnéia S
authors.initials: SS
authors.lastname: Santos
authors.affiliation: Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, Sao Paulo, Brazil.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Carmo
authors.affiliation: Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, Sao Paulo, Brazil.
authors.forename: Milena K C
authors.initials: MK
authors.lastname: Brunialti
authors.affiliation: Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, Sao Paulo, Brazil.
authors.forename: Flavia R
authors.initials: FR
authors.lastname: Machado
authors.affiliation: Hospital Sírio Libanes, Universidade de Sao Paulo, Ribeirao Preto, Brazil.
authors.forename: Luciano C
authors.initials: LC
authors.lastname: Azevedo
authors.affiliation: Hospital Israelita Albert Einstein, Universidade de Sao Paulo, Ribeirao Preto, Brazil.
authors.forename: Murillo
authors.initials: M
authors.lastname: Assunção
authors.affiliation: Faculdade de Medicina, Universidade de Sao Paulo, Ribeirao Preto, Brazil.
authors.forename: Sílvia C
authors.initials: SC
authors.lastname: Trevelin
authors.affiliation: Faculdade de Medicina, Universidade de Sao Paulo, Ribeirao Preto, Brazil.
authors.forename: Fernando Q
authors.initials: FQ
authors.lastname: Cunha
authors.affiliation: Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, Sao Paulo, Brazil. rsalomao@unifesp.br.
authors.forename: Reinaldo
authors.initials: R
authors.lastname: Salomao
keywords: IL-6; Monocytes; Nitric oxide; Phagocytosis; Reactive oxygen species; TNF-α