title: Sera from patients with active systemic lupus erythematosus patients enhance the toll-like receptor 4 response in monocyte subsets.
abstract: BACKGROUND
  Systemic Lupus Erythematosus (SLE) is an auto-immune disease whose complex pathogenesis remains unraveled. Here we aim to explore the inflammatory ability of SLE patients' sera upon peripheral blood (PB) monocyte subsets and myeloid dendritic cells (mDCs) obtained from healthy donors.
  
  
  METHODS
  In this study we included 11 SLE patients with active disease (ASLE), 11 with inactive disease (ISLE) and 10 healthy controls (HC). PB from healthy donors was stimulated with patients' sera, toll-like receptor (TLR) 4 ligand - lipopolysaccharide or both. The intracellular production of TNF-α was evaluated in classical, non-classical monocytes and mDCs, using flow cytometry. TNF-α mRNA expression was assessed in all these purified cells, after sera treatment.
  
  
  RESULTS
  We found that sera of SLE patients did not change spontaneous TNF-α production by monocytes or dendritic cells. However, upon stimulation of TLR4, the presence of sera from ASLE patients, but not ISLE, significantly increased the intracellular expression of TNF-α in classical and non-classical monocytes. This ability was related to titers anti-double stranded DNA antibodies in the serum. High levels of anti-TNF-α in the patients' sera were associated with increased TNF-α expression by co-cultured mDCs. No relationship was found with the levels of a wide variety of other pro-inflammatory cytokines. A slight increase of TNF-α mRNA expression was observed in these purified cells when they were cultured only in the presence of SLE serum.
  
  
  CONCLUSIONS
  Our data suggest that SLE sera induce an abnormal in vitro TLR4 response in classical and non-classical monocytes, reflected by a higher TNF-α intracellular expression. These effects may be operative in the pathogenesis of SLE.
authors.affiliation: Blood and Transplantation Center of Coimbra, Portuguese Institute of Blood and Transplantation, Quinta da Vinha Moura, São Martinho do Bispo, 3041-861 Coimbra, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Carvalheiro
authors.affiliation: College of Health Technology of Coimbra, Rua 5 de Outubro, São Martinho do Bispo, 3046-854 Coimbra, Portugal.
authors.forename: Diane
authors.initials: D
authors.lastname: Gomes
authors.affiliation: HPV Immunology Laboratory, Frederick National Laboratory for Cancer Research, Building 469, 21702 Frederick, MD USA.
authors.forename: Ligia A
authors.initials: LA
authors.lastname: Pinto
authors.affiliation: Rheumatology Department, Centro Hospitalar e Universitário de Coimbra, Praceta Prof. Mota Pinto, 3000-075 Coimbra, Portugal ; Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, Portugal ; School of Health Sciences, University of Beira Interior, Avenida Infante D. Henrique, 6200-506 Covilhã, Portugal.
authors.forename: Luis
authors.initials: L
authors.lastname: Inês
authors.affiliation: Blood and Transplantation Center of Coimbra, Portuguese Institute of Blood and Transplantation, Quinta da Vinha Moura, São Martinho do Bispo, 3041-861 Coimbra, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Lopes
authors.affiliation: Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Henriques
authors.affiliation: Blood and Transplantation Center of Coimbra, Portuguese Institute of Blood and Transplantation, Quinta da Vinha Moura, São Martinho do Bispo, 3041-861 Coimbra, Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Pedreiro
authors.affiliation: Blood and Transplantation Center of Coimbra, Portuguese Institute of Blood and Transplantation, Quinta da Vinha Moura, São Martinho do Bispo, 3041-861 Coimbra, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Martinho
authors.affiliation: Blood and Transplantation Center of Coimbra, Portuguese Institute of Blood and Transplantation, Quinta da Vinha Moura, São Martinho do Bispo, 3041-861 Coimbra, Portugal.
authors.forename: Hélder
authors.initials: H
authors.lastname: Trindade
authors.affiliation: Laboratory of Experimental Immunology, Cancer and Inflammation Program, National Cancer Institute at Frederick, Building 560, 21702-1201 Frederick, MD USA.
authors.forename: Howard A
authors.initials: HA
authors.lastname: Young
authors.affiliation: Rheumatology Department, Centro Hospitalar e Universitário de Coimbra, Praceta Prof. Mota Pinto, 3000-075 Coimbra, Portugal ; Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, Celas, 3000-548 Coimbra, Portugal.
authors.forename: José António Pereira
authors.initials: JA
authors.lastname: da Silva
authors.affiliation: Blood and Transplantation Center of Coimbra, Portuguese Institute of Blood and Transplantation, Quinta da Vinha Moura, São Martinho do Bispo, 3041-861 Coimbra, Portugal ; College of Health Technology of Coimbra, Rua 5 de Outubro, São Martinho do Bispo, 3046-854 Coimbra, Portugal.
authors.forename: Artur
authors.initials: A
authors.lastname: Paiva
keywords: Classical monocytes; Cytokines; Myeloid dendritic cells; Non-classical monocytes; Serum; Systemic lupus erythematosus; Toll like receptor 4