Reduced pro-inflammatory profile of γδT cells in pregnant patients with rheumatoid arthritis

BACKGROUND During pregnancy, many patients with rheumatoid arthritis (RA) experience disease improvement, whereas patients with ankylosing spondylitis often suffer from persistent active disease. Here we investigated whether pregnancy-related changes in disease activity were associated with changes in the proportion and function of γδT cells. METHODS The study population comprised 55 patients with RA, 31 patients with ankylosing spondylitis, and 35 healthy controls. Among these participants, 28 RA patients, 21 ankylosing spondylitis patients, and 23 healthy controls were investigated once before conception when possible, at each trimester of pregnancy, and at 8 weeks postpartum. Data were compared with age-matched non-pregnant patients to obtain disease-related background. In all subjects, peripheral Vδ1 and Vδ2 T cells were analyzed for cell frequencies, the activation marker CD69, the cytotoxicity markers NKG2D and NKG2A, and the intracellular cytokines tumor necrosis factor (TNF)α, interferon (IFN)γ, interleukin (IL)-17 and IL-10. RESULTS Pregnant patients showed a decreased Vδ2/Vδ1 ratio in the third trimester, which resulted from a slightly reduced proportion of Vδ2 cells. Changes in RA disease activity during pregnancy and postpartum were not associated with numerical proportions of γδT cells but with changes of the cell activation marker CD69 on Vδ1 and Vδ2 cells. Only RA patients showed reduced proportions of TNFα-positive Vδ1and Vδ2 cells and IFNγ-positive Vδ2 cells at the third trimester of pregnancy, a finding that was not apparent in the entire population of CD3 T cells. The proportions of IL-17-positive γδT cells and IL-10-positive γδT cells did not differ between pregnant and non-pregnant women of the different groups. CONCLUSIONS Changes of disease activity in pregnant RA patients were associated with functional changes in both γδT cell subsets. This reduced pro-inflammatory profile of γδT cells might contribute to the immunomodulation resulting in pregnancy-induced improvement of RA.

β2-microglobulin is a systemic pro-aging factor that impairs cognitive function and neurogenesis

Aging drives cognitive and regenerative impairments in the adult brain, increasing susceptibility to neurodegenerative disorders in healthy individuals. Experiments using heterochronic parabiosis, in which the circulatory systems of young and old animals are joined, indicate that circulating pro-aging factors in old blood drive aging phenotypes in the brain. Here we identify β2-microglobulin (B2M), a component of major histocompatibility complex class 1 (MHC I) molecules, as a circulating factor that negatively regulates cognitive and regenerative function in the adult hippocampus in an age-dependent manner. B2M is elevated in the blood of aging humans and mice, and it is increased within the hippocampus of aged mice and young heterochronic parabionts. Exogenous B2M injected systemically, or locally in the hippocampus, impairs hippocampal-dependent cognitive function and neurogenesis in young mice. The negative effects of B2M and heterochronic parabiosis are, in part, mitigated in the hippocampus of young transporter associated with antigen processing 1 (Tap1)-deficient mice with reduced cell surface expression of MHC I. The absence of endogenous B2M expression abrogates age-related cognitive decline and enhances neurogenesis in aged mice. Our data indicate that systemic B2M accumulation in aging blood promotes age-related cognitive dysfunction and impairs neurogenesis, in part via MHC I, suggesting that B2M may be targeted therapeutically in old age.

Bok Is Not Pro-Apoptotic But Suppresses Poly ADP-Ribose Polymerase-Dependent Cell Death Pathways and Protects against Excitotoxic and Seizure-Induced Neuronal Injury.

UNLABELLED Bok (Bcl-2-related ovarian killer) is a Bcl-2 family member that, because of its predicted structural homology to Bax and Bak, has been proposed to be a pro-apoptotic protein. In this study, we demonstrate that Bok is highly expressed in neurons of the mouse brain but thatbokwas not required for staurosporine-, proteasome inhibition-, or excitotoxicity-induced apoptosis of cultured cortical neurons. On the contrary, we found thatbok-deficient neurons were more sensitive to oxygen/glucose deprivation-induced injuryin vitroand seizure-induced neuronal injuryin vivo Deletion ofbokalso increased staurosporine-, excitotoxicity-, and oxygen/glucose deprivation-induced cell death inbax-deficient neurons. Single-cell imaging demonstrated thatbok-deficient neurons failed to maintain their neuronal Ca(2+)homeostasis in response to an excitotoxic stimulus; this was accompanied by a prolonged deregulation of mitochondrial bioenergetics.bokdeficiency led to a specific reduction in neuronal Mcl-1 protein levels, and deregulation of both mitochondrial bioenergetics and Ca(2+)homeostasis was rescued by Mcl-1 overexpression. Detailed analysis of cell death pathways demonstrated the activation of poly ADP-ribose polymerase-dependent cell death inbok-deficient neurons. Collectively, our data demonstrate that Bok acts as a neuroprotective factor rather than a pro-death effector during Ca(2+)- and seizure-induced neuronal injuryin vitroandin vivo SIGNIFICANCE STATEMENT Bcl-2 proteins are essential regulators of the mitochondrial apoptosis pathway. The Bcl-2 protein Bok is highly expressed in the CNS. Because of its sequence similarity to Bax and Bak, Bok has long been considered part of the pro-apoptotic Bax-like subfamily, but no studies have yet been performed in neurons to test this hypothesis. Our study provides important new insights into the functional role of Bok during neuronal apoptosis and specifically in the setting of Ca(2+)- and seizure-mediated neuronal injury. We show that Bok controls neuronal Ca(2+)homeostasis and bioenergetics and, contrary to previous assumptions, exerts neuroprotective activitiesin vitroandin vivo Our results demonstrate that Bok cannot be placed unambiguously into the Bax-like Bcl-2 subfamily of pro-apoptotic proteins.