Antioxidants improve antibacterial function in hyperoxia-exposed macrophages

Abstract

Hyperoxia and pulmonary infections are well known to increase the risk of acute and chronic lung injury in newborn infants, but it is not clear whether hyperoxia directly increases the risk of pneumonia. The purpose of this study was to examine: 1) the effects of hyperoxia and antioxidant enzymes on inflammation and bacterial clearance in mononuclear cells; and 2) developmental differences between adult and neonatal mononuclear cells in response to hyperoxia. Mouse macrophages were exposed to either room air (RA) or 95% O 2 for 24 h and then incubated with P. aeruginosa (PA). After 1 h, bacterial adherence, phagocytosis and macrophage inflammatory protein (MIP)-1α production were analyzed. Bacterial adherence increased 5.8 fold (P<0.0001), phagocytosis decreased 60% (P<0.05), and MIP-1α production increased 49% (P<0.05) in response to hyperoxia. Overexpression of MnSOD or catalase significantly decreased bacterial adherence by 30.5%, but only MnSOD significantly improved bacterial phagocytosis and attenuated MIP-1α production. When monocytes from newborns and adults were exposed to hyperoxia, phagocytosis was impaired in both groups. However, adult monocytes were significantly more impaired than neonatal monocytes. Data indicate that hyperoxia significantly increases bacterial adherence while impairing function of mononuclear cells, with adult cells more impaired than neonatal cells. MnSOD reduces bacterial adherence and inflammation and improves bacterial phagocytosis in mononuclear cells in response to hyperoxia, which should minimize the development of oxidant-induced lung injury as well as reduce nosocomial infections.

Hydrogen peroxide enhances phagocytosis ofPseudomonas aeruginosain hyperoxia

“…These results suggest that it is unlikely that H 2 O 2 contributes to hyperoxia-suppressed phagocytic activity unless the local concentration of H 2 O 2 exceeded 500 µM. Our finding is consistent with an early report showing that catalase did not exhibit a significant effect on macrophage phagocytosis in hyperoxia, although the effect of hyperoxia on bacterial adherence to mononuclear cells was ameliorated by catalase (Arita et al, 2007).…”

Genotoxic damage in polychaetes: A study of species and cell-type sensitivities

“…Amoebocytes are mainly involved in the immune functioning of the polychaete [17] whilst eleocytes have a mainly nutritive role for the developing gametes [18]. Antioxidants are known to improve antibacterial function in human leukocytes and mouse macrophages [38][39][40] and so are likely to be present in greater quantities in a cell with an immune function.…”

Ascorbic Acid Attenuates Hyperoxia-Compromised Host Defense against Pulmonary Bacterial Infection

“…Treatment of hyperoxia-exposed macrophages with antioxidants, such as superoxide dismutase and procysteine, can preserve actin cytoskeleton organization and increase the phagocytosis of bacteria (18,26). Hyperoxia-exposed cells overexpressing antioxidant enzyme, manganese superoxide dismutase, exhibit reduced bacterial adherence, increased phagocytic activity (26,27), and attenuated ROS-induced damage (28). These aforementioned findings suggest that antioxidants may be useful in attenuating ROS-induced cellular damage and impairment of macrophage functions.…”

“…Exposure of cultured macrophages to hyperoxia induces actin oxidation and subsequent cytoskeleton disorganization, resulting in a decrease in the ability to phagocytose bacteria (16,18). Treatment of hyperoxia-exposed macrophages with antioxidants, such as superoxide dismutase and procysteine, can preserve actin cytoskeleton organization and increase the phagocytosis of bacteria (18,26). Hyperoxia-exposed cells overexpressing antioxidant enzyme, manganese superoxide dismutase, exhibit reduced bacterial adherence, increased phagocytic activity (26,27), and attenuated ROS-induced damage (28).…”