title: Mitochondrial Superoxide Signaling Contributes to Norepinephrine-Mediated T-Lymphocyte Cytokine Profiles.
abstract: Norepinephrine (NE) produces multifaceted regulatory patterns in T-lymphocytes. Recently, we have shown that NE utilizes redox signaling as evidenced by increased superoxide (O2●-) causally linked to the observed changes in these cells; however, the source of this reactive oxygen species (ROS) remains elusive. Herein, we hypothesized that the source of increased O2●- in NE-stimulated T-lymphocytes is due to disruption of mitochondrial bioenergetics. To address this hypothesis, we utilized purified mouse splenic CD4+ and CD8+ T-lymphocytes stimulated with NE and assessed O2●- levels, mitochondrial metabolism, cellular proliferation, and cytokine profiles. We demonstrate that the increase in O2●- levels in response to NE is time-dependent and occurs at later points of T-lymphocyte activation. Moreover, the source of O2●- was indeed the mitochondria as evidenced by enhanced MitoSOX Red oxidation as well as abrogation of this signal by the addition of the mitochondrial-targeted O2●--scavenging antioxidant MitoTempol. NE-stimulated T-lymphocytes also demonstrated decreased mitochondrial respiratory capacity, which suggests disruption of mitochondrial metabolism and the potential source of increased mitochondrial O2●-. The effects of NE in regards to redox signaling appear to be adrenergic receptor-dependent as specific receptor antagonists could reverse the increase in O2●-; however, differential receptors regulating these processes were observed in CD4+ versus CD8+ T-lymphocytes. Finally, mitochondrial O2●- was shown to be mechanistic to the NE-mediated T-lymphocyte phenotype as supplementation of MitoTempol could reverse specific changes in cytokine expression observed with NE treatment. Overall, these studies indicate that mitochondrial metabolism and O2●--mediated redox signaling play a regulatory role in the T-lymphocyte response to NE.
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States of America.
authors.forename: Adam J
authors.identifier: http://orcid.org/0000-0003-3404-1428
authors.initials: AJ
authors.lastname: Case
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States of America.
authors.forename: Colton T
authors.initials: CT
authors.lastname: Roessner
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States of America.
authors.forename: Jun
authors.initials: J
authors.lastname: Tian
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States of America.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Zimmerman
mesh_terms: D000818:Animals; D000069445:Atomoxetine Hydrochloride / Q000494:pharmacology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology*; D010084:Oxidation-Reduction; D011941:Receptors, Adrenergic / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013481:Superoxides / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D016207:Cytokines; D011941:Receptors, Adrenergic; D013481:Superoxides; D000069445:Atomoxetine Hydrochloride; D009638:Norepinephrine