Premium
Inhibition of caspase‐dependent spontaneous apoptosis via a cAMP‐protein kinase A dependent pathway in neutrophils from sickle cell disease patients
Author(s) -
Conran Nicola,
Almeida Camila B.,
Lanaro Carolina,
Ferreira Renata Proença,
Traina Fabiola,
Saad Sara T. O.,
Costa Fernando F.
Publication year - 2007
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.2007.06748.x
Subject(s) - apoptosis , protein kinase a , inflammation , cytokine , kinase , immunology , endocrinology , medicine , biology , microbiology and biotechnology , biochemistry
Summary Sickle cell disease (SCD) is a chronic inflammatory condition characterized by high leucocyte counts, altered cytokine levels and endothelial cell injury. As the removal of inflammatory cells by apoptosis is fundamental for the resolution of inflammation, we aimed to determine whether the leucocyte apoptotic process is altered in SCD. Neutrophils from SCD individuals showed an inhibition of spontaneous apoptosis when cultured in vitro , in the presence of autologous serum for 20 h. Intracellular cyclic adenosine monophosphate (cAMP) levels were approximately twofold increased in SCD neutrophils; possible cAMP‐upregulating factors present in SCD serum include interleukin‐8, granulocyte‐macrophage colony‐stimulating factor and prostaglandin. Accordingly, co‐incubation of SCD neutrophils with KT5720, a cAMP‐dependent protein kinase (PKA) inhibitor, abrogated increased SCD neutrophil survival. Caspase‐3 activity was also significantly diminished in SCD neutrophils cultured for 16 h and this activity was restored when cells were co‐incubated with KT5720. BIRC2 (encoding cellular inhibitor of apoptosis protein 1, cIAP 1 ), MCL1 and BAX expression were unaltered in SCD neutrophils; however, BIRC3 (encoding the caspase inhibitor, cIAP 2 ), was expressed at significantly higher levels. Thus, we report an inhibition of spontaneous SCD neutrophil apoptosis that appears to be mediated by upregulated cAMP‐PKA signalling and decreased caspase activity. Increased neutrophil survival may have significant consequences in SCD; contributing to leucocytosis, tissue damage and exacerbation of the chronic inflammatory state.