D and mean persistence of direction were 1516647 calculated from the tracks generated in (A). ** = p,0.001. doi:10.1371/journal.pone.0054869.gNox2 and ChemotaxisFigure 5. Nox2KO BMMs have reduced ERK phosphorylation downstream of CSF-1. A) WT and Nox2KO BMMs were CSF-1 deprived, then re-stimulated with CSF-1for the times indicated. Cells were lysed 
and probed for pAKt, pERK and total protein.B) autoradiographs were analysed 
using AndorIQ and levels of pERK1, pERK2 and pAKT were normalised to loading controls. Data represents three independent experiments. * = p,0.05. doi:10.1371/journal.pone.0054869.gNADPH oxidase have also been shown to be involved in the RE-640 web migration of other cell types. Nox4 has also recently been found to be a key player in the regulation of stress fibre formation and focal adhesion turnover in VSMCs [11]. These findings suggest a potentially novel mechanism of local ROS production by which focal adhesion turnover is coordinated. Certainly a role of Nox2 in the regulation of such adhesion formation in BMM could explain the difference observed in their shape and then in their speed and persistence. Further studies of differences in the expression of integrins would increase the understanding of the exact underlying mechanism whereby the loss of Nox2 results in a reduction in the speed of migration in BMM. An important role for Nox1 in the migration of VSMC to bFGF agonist stimulation has also been identified [43] in rat SMC where inhibition of Nox1 significantly blocked migration. In summary in order to initiate inflammation and tissue repair, the migration of macrophages into tissue is an important initial step. However the loss of Nox2 results in significant reduction in the random migration of BMM. On interrogating the BMM towards a directed target we have shown that the loss of Nox2 proved crucial as its loss resulted in the complete loss of chemotaxis. Nox2 was also important in the BMM speed and persistence towards a CSF-1 gradient with significant reductions in both. This loss of Nox2 also manifested itself in a reduced ERK1/ 2 phosphorylation and spreading responses to CSF-1 stimulation.expression is necessary in response to CSF-1 stimulated migration. This in-vitro behaviour could in part be related to in vivo phenotypes associated with Nox2. A complete deficiency of Nox2, as in patients with chronic granulomatous disease (CGD), is associated with hyperinflammation, suggesting that the normal functions of Nox2 in macrophages and potentially other inflammatory cells are essential in restricting or resolving inflammation. On the other hand, Nox2KO mice are protected against fibrosis that accompanies inflammatory repair processes in the liver [44,45], heart [46,47,48] and kidneys [49,50]. Furthermore, specific inhibition of Nox2 reduces macrophage infiltration into vessels in a model of angiotensin II-induced hypertension [51] whilst macrophages lacking Nox2 oxidase activity are reported to infiltrate less efficiently into atherosclerotic lesions [52] and the aorta [53]. No mechanisms to explain these get 78919-13-8 observations were reported in these studies. Our current results suggest that Nox2dependent regulation of macrophage migration may underlie the effects on macrophage infiltration previously reported in experimental models of atherosclerosis and vascular disease. They further suggest that inhibition of Nox2 may be beneficial in such settings (all vascular disease) by inhibiting inflammatory infiltration. The development of no.D and mean persistence of direction were 1516647 calculated from the tracks generated in (A). ** = p,0.001. doi:10.1371/journal.pone.0054869.gNox2 and ChemotaxisFigure 5. Nox2KO BMMs have reduced ERK phosphorylation downstream of CSF-1. A) WT and Nox2KO BMMs were CSF-1 deprived, then re-stimulated with CSF-1for the times indicated. Cells were lysed and probed for pAKt, pERK and total protein.B) autoradiographs were analysed using AndorIQ and levels of pERK1, pERK2 and pAKT were normalised to loading controls. Data represents three independent experiments. * = p,0.05. doi:10.1371/journal.pone.0054869.gNADPH oxidase have also been shown to be involved in the migration of other cell types. Nox4 has also recently been found to be a key player in the regulation of stress fibre formation and focal adhesion turnover in VSMCs [11]. These findings suggest a potentially novel mechanism of local ROS production by which focal adhesion turnover is coordinated. Certainly a role of Nox2 in the regulation of such adhesion formation in BMM could explain the difference observed in their shape and then in their speed and persistence. Further studies of differences in the expression of integrins would increase the understanding of the exact underlying mechanism whereby the loss of Nox2 results in a reduction in the speed of migration in BMM. An important role for Nox1 in the migration of VSMC to bFGF agonist stimulation has also been identified [43] in rat SMC where inhibition of Nox1 significantly blocked migration. In summary in order to initiate inflammation and tissue repair, the migration of macrophages into tissue is an important initial step. However the loss of Nox2 results in significant reduction in the random migration of BMM. On interrogating the BMM towards a directed target we have shown that the loss of Nox2 proved crucial as its loss resulted in the complete loss of chemotaxis. Nox2 was also important in the BMM speed and persistence towards a CSF-1 gradient with significant reductions in both. This loss of Nox2 also manifested itself in a reduced ERK1/ 2 phosphorylation and spreading responses to CSF-1 stimulation.expression is necessary in response to CSF-1 stimulated migration. This in-vitro behaviour could in part be related to in vivo phenotypes associated with Nox2. A complete deficiency of Nox2, as in patients with chronic granulomatous disease (CGD), is associated with hyperinflammation, suggesting that the normal functions of Nox2 in macrophages and potentially other inflammatory cells are essential in restricting or resolving inflammation. On the other hand, Nox2KO mice are protected against fibrosis that accompanies inflammatory repair processes in the liver [44,45], heart [46,47,48] and kidneys [49,50]. Furthermore, specific inhibition of Nox2 reduces macrophage infiltration into vessels in a model of angiotensin II-induced hypertension [51] whilst macrophages lacking Nox2 oxidase activity are reported to infiltrate less efficiently into atherosclerotic lesions [52] and the aorta [53]. No mechanisms to explain these observations were reported in these studies. Our current results suggest that Nox2dependent regulation of macrophage migration may underlie the effects on macrophage infiltration previously reported in experimental models of atherosclerosis and vascular disease. They further suggest that inhibition of Nox2 may be beneficial in such settings (all vascular disease) by inhibiting inflammatory infiltration. The development of no.
