OLIGODEOXINUCLEOTIDES CONTAINING CPG MOTIFS (CPG) INDUCE ARGINASE II ACTIVITY IN MURINE MACROPHAGES BY A MECHANISM DEPENDENT ON IFNg
Liscovsky M; Maletto B; Alignani D; Ranocchia R, Morón G; Pistoresi M.C
CIBICI-CONICET- Facultad de Ciencias Químicas–UNC-Córdoba-Argentina
cpistore@mail.fcq.unc.edu.ar
CpG generate a Th1 type response that may include feedback mechanisms. In this work we investigated the mechanism by which CpG modulate arginase activity (AA), an antinflamatory factor. Bone marrow-derived macrophages (BMMØ) were cultured with medium, CpG, IFNg or CpG+IFNg for 48h. CpG alone were unable to induce AA but CpG+IFNg augmented it (medium:78±13;CpG:83±7;CpG+IFNg:187±5 mU/mg protein). This effect was correlated with increased expression of arginase II isoform. Since IL10 has been implied in AA regulation, it was dosed in culture supernants. CpG alone augmented IL-10 secretion, but IL10 level dramatically diminished in presence of IFNg (medium: 272±113;CpG: 583±76;CpG+IFNg:70±30 pg/mL). Upon incubation of BMMØ with IFNg, washing and subsequent stimulation with CpG, AA was increased (medium: 56±2;CpG:183±59 mU/mg protein). However, BMMØ preincubated with CpG and then with IFNg did not exhibit this effect. Finally, we investigated the relationship between AA and iNOS. BMMØ with CpG+IFNg peaked NO accumulation at 48h and then remained stable while AA increased over 72h.
These observations suggest that increase in AA in response to CpG-ODN is dependent on IFNg priming, but independent on IL10 production. The increasing AA in time might be a regulatory mechanism of NO formation. To sum up, response of BMMØs to CpG is regulated by IFNg, a cytoquine produced in vivo in response to this stimulus.