Inflammation and Immunity

NOX1 Causes Ileitis in Mice Deficient in Glutathione Peroxidase-1 and -2 Steve Esworthy1, Byung-Wook Kim1, Joanna Wang1, Joni Chow1, James H. Doroshow2, and Fong-Fong Chu1 1City of Hope, United States, 2National Cancer Institute, NIH, United States We previously reported that mice deficient in two Se-dependent glutathione peroxidases, GPx1 and GPx2, have spontaneous ileocolitis. the disease severity depends on mouse genetic background, while C57BL/6J (B6) GPx1/2-DKO mice have moderate ileitis and mild colitis, when 129S1Svlm/J (129) DKO mice have severe ileocolitis. Since GPxs are antioxidant enzymes, we hypothesized that elevated reactive oxygen species (ROS) trigger inflammation in these DKO mice. to test whether NADPH oxidase 1 (Nox1), which is highly expressed in the colon, contributes to colitis, we generated B6 triple-KO (TKO) mice to study their phenotype. Since the Nox1 gene is X-linked, we analyzed NOX1 effect on in male B6 TKO and female B6 DKO with Nox1+/- (het-TKO) genotype. the male TKO mice have virtually abolished the disease signs in the ileum and colon exhibited in the DKO mice, while the female het-TKO mice have attenuated disease signs. the DKO mice have slower growth starting at 22 days of age for males and 31days for females; male TKO and female het-TKO mice have the same weight gain as non-DKO mice. the male TKO and female TKO mice have normal length of small and large intestine, while both male and female DKO mice have shorter small intestine and male DKO mice also have shorter large intestine measured at 50-51 days of age. Furthermore, the male TKO mice have ameliorated the pathology, including the high apoptosis in the crypt epithelium, which are characteristics of the DKO ileum. the female het-DKO mice have attenuated ileal pathology. the dramatic impact observed in the het-TKO mice is likely due to random or imprinted X-chromosome inactivation, which produces mosaic expression of Nox1. Thus, we conclude that NOX1 is the major source of ROS to induce ileocolitis.

Bacterial Antioxidants Restrict Immune Function by Limiting Actin Mobilization and Calcium Uptake Via the Transient Receptor Potential Ion Channels Nicole L Flaherty1, Judith a Stolwijk1, Mohamed Trebak1, and J. Andres Melendez1 1College of Nanoscale Science and Engineering, SUNY, United States As an innate defense mechanism, macrophages are capable of producing reactive oxygen species (ROS) including superoxide (O2

-) and hydrogen peroxide (H2O2). ROS serve as a means to weaken/kill pathogens, but can also act as secondary messengers by modifying host signaling responses involved in immune function. the gram negative bacterium F. tularensis utilizes its antioxidant armature to limit the host immune response but the mechanism behind this suppression has not been defined. Here we establish that F. tularensis limits Ca2+ entry thereby preventing actin polymerization and further bacterial entry in a

redox-dependent fashion. Wild-type (LVS) or catalase deficient F. tularensis in their H2O2 scavenging capacity, 1 pM/sec and 0.15 pM/sec, respectively. in vitro infection of murine macrophages with KatG augments actin polymerization and intracellular calcium as compared to its wild-type counterpart. Increases in infection can be abrogated by 2-Aminoethyl diphenylborinate (2APB), a TRP Ca2+ channel inhibitor. These data provide compelling evidence that bacterial antioxidants harness ROS to limit Ca2+ signaling and restrict host immune function.

The Cellular Distribution of Extracellular Superoxide Dismutase in Macrophages Is Altered by Cellular Activation Randi Heidemann Gottfredsen1, David Goldstrohm2, Ulrike Gabriele Larsen1, Russel Bowler2, and Steen Vang Petersen1 1Aarhus University, Denmark, 2National Jewish Health, Denver, United States The antioxidant extracellular superoxide dismutase (EC-SOD) is the only extracellular protein responsible for enzymatic dismutation of superoxide producing molecular oxygen and hydrogen peroxide. a number of pulmonary diseases are characterized by the influx of inflammatory cells including neutrophils and macrophages, which are known to express EC-SOD. Using a number of animal models of lung disease, it has been shown that over-expression of EC-SOD attenuates the inflammatory response by reducing the influx of neutrophils whereas the absence of EC-SOD exacerbate the response. Moreover, recent evidence suggests that EC-SOD may also play a role in the activity and maturation of the inflammatory response. to further characterize the role of EC-SOD in the inflammatory response, we have analyzed the expression of EC-SOD in bone marrow-derived macrophages isolated from both wild-type animals and animals expressing the natural occurring R213G variant. We show that whereas un-stimulated and resting macrophages express EC-SOD, the protein is not secreted into the culture medium, but remains associated to the cell surface. However, upon cellular activation induced by LPS, EC-SOD is redistributed and can be detected in culture medium as well as in in lipid rafts. Interestingly, we find that EC-SOD recovered from the culture medium had lost the affinity for heparin, albeit the recovered protein did not present an increased amount of cleaved protein lacking the ECM-binding region. These data suggest a dynamic role of EC-SOD in the inflammatory response mounted by macrophages.

Covalent Modification of the Pro-Inflammatory Cytokine MIF by Dietary and Endogenous Electrophiles Nina Dickerhof1, Anthony J Kettle1, and Mark B Hampton1 1University of Otago, Christchurch, New Zealand Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that plays an important role in promotion and

doi: 10.1016/j.freeradbiomed.2013.10.467

doi: 10.1016/j.freeradbiomed.2013.10.468

doi: 10.1016/j.freeradbiomed.2013.10.469