Monocyte-derived macrophages (MoMacs) fail to mature in CGD mice, an effect driven more by the milieu than intrinsic absence of Nox2.
Prolonged recruitment of MoMacs in CGD peritonitis results in nascent granulomata within fibrin clots at ectopic sites (g. diaphragm).
Loss of NADPH oxidase activity leads to altered phagocyte responses and exaggerated inflammation in Chronic Granulomatous Disease (CGD). We sought to assess the effects of Nox2 absence on monocyte-derived macrophages (MoMacs) in gp91phox-/y mice during zymosan-induced peritonitis. MoMacs from CGD and wild type (WT) peritonea were characterized over time after zymosan injection. Though numbers lavaged from both genotypes were virtually identical, there were marked differences in maturation: newly recruited WT MoMacs rapidly enlarged and matured, losing Ly6C and gaining MHCII, CD206 and CD36, while CGD MoMacs remained small and were mostly Ly6C+MHCII-. RNAseq analyses showed few intrinsic differences between genotypes in newly recruited MoMacs but significant differences with time. WT MoMacs demonstrated changes in metabolism, adhesion and reparative functions, while CGD MoMacs remained inflammatory. PKH dye labeling demonstrated that while WT MoMacs were mostly recruited within the first 24h and remained in the peritoneum while maturing and enlarging, CGD monocytes streamed into the peritoneum for days with many migrating to the diaphragm where they were found in fibrin(ogen) clots surrounding clusters of neutrophils in nascent pyogranulomata. Importantly, these observations appeared to be driven by milieu: adoptive transfer of CGD MoMacs into inflamed peritonea of WT mice resulted in immunophenotypic maturation and normal behavior, whereas altered maturation/behavior of WT MoMacs resulted from transfer into inflamed peritonea of CGD mice. Additionally, Nox2-deficient MoMacs behaved similarly to their Nox2-sufficient counterparts within the largely WT milieu of mixed bone marrow chimeras. These data demonstrate persistent recruitment with fundamental failure of MoMac maturation in CGD.