Oxidative stress has been implicated in the pathogenesis of Alzheimer's disease (AD). Mitochondrial dysfunction is linked to oxidative stress and reactive oxygen species (ROS) in neurotoxicity during AD. Impaired mitochondrial metabolism has been associated with mitochondrial dysfunction in brain damage of AD. While the role of NADPH oxidase 4 (NOX4), a major source of ROS, has been identified in brain damage, the mechanism by which NOX4 regulates ferroptosis of astrocytes in AD remains unclear. Here, we show that the protein levels of NOX4 were significantly elevated in impaired astrocytes of cerebral cortex from patients with AD and APP/PS1 double-transgenic mouse model of AD. The levels of 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA), a marker of oxidative stress-induced lipid peroxidation, were significantly also elevated in impaired astrocytes of patients with AD and mouse AD. We demonstrate that the over-expression of NOX4 significantly increases the impairment of mitochondrial metabolism by inhibition of mitochondrial respiration and ATP production via the reduction of five protein complexes in the mitochondrial ETC in human astrocytes. Moreover, the elevation of NOX4 induces oxidative stress by mitochondrial ROS (mtROS) production, mitochondrial fragmentation, and inhibition of cellular antioxidant process in human astrocytes. Furthermore, the elevation of NOX4 increased ferroptosis-dependent cytotoxicity by the activation of oxidative stress-induced lipid peroxidation in human astrocytes. These results suggest that NOX4 promotes ferroptosis of astrocytes by oxidative stress-induced lipid peroxidation via the impairment of mitochondrial metabolism in AD.

Introduction: Interleukin (IL)-17 is a proinflammatory cytokine that is produced largely by a unique CD4⁺ T-helper (Th) subset called Th17 cells. The development of Th17 cells is suppressed by interferon (IFN)-γ produced by Th1 cells, suggesting cross-regulation between Th17 and Th1 cells. Thus, this study analyzed the balance of CD4⁺ Th17 and Th1 cell responses in peripheral blood from patients with systemic lupus erythematosus (SLE) and healthy subjects. Methods: Twenty-five adult patients with SLE and 26 healthy subjects matched for gender and age (± 2 years) were recruited. Peripheral blood mononuclear cells (PBMCs) from patients and healthy subjects were stimulated for 4 h ex vivo with phorbol myristate acetate (PMA) and ionomycin. The frequency of CD4⁺ T cells producing IL-17 and/or IFN-γ was measured by using flow cytometry. Expression of Th17-associated chemokine receptors CCR4 and CCR6 on CD4⁺ T cells as well as plasma levels of Th17-polarizing cytokines were assessed. Disease activity was evaluated by the SLE disease activity index score (SLEDAI). Unpaired t test and Pearson correlation were used for statistical analyses. Results: Patients with SLE had an increased frequency of CD4⁺IL-17⁺ T cells compared with healthy subjects. However, the frequency of CD4⁺IFN-γ⁺ T cells was similar between the two groups, indicating an altered balance of Th17 and Th1 cell responses in SLE. Patients with SLE also had an increased frequency of CD4⁺CCR4⁺CCR6⁺ T cells that are known to produce IL-17. The frequency of CD4⁺IL-17⁺ T cells and CD4⁺CCR4⁺CCR6⁺ T cells correlated with disease activity. In measuring plasma levels of the Th17-polarizing cytokines, levels of IL-6 were higher in patients with SLE than in healthy subjects, although levels of IL-1β, IL-21, IL-23, and transforming growth factor (TGF)-β were not different between the two groups. Conclusions: We demonstrate an enhanced Th17 cell response that correlates with disease activity in patients with SLE, suggesting a role for IL-17 in the pathogenesis of lupus. Our data indicate that the mechanisms involved in balancing Th1 and Th17 regulation, as well as in producing IL-6, are aberrant in SLE, leading to an increased Th17 response. We suggest that CCR4 and CCR6 expression on CD4⁺ T cells should be considered as markers of disease activity, and that IL-17 blocking may offer a therapeutic target in SLE.

Astrocytes are involved in various processes in the central nervous system (CNS). As the most abundant cell type in the CNS, astrocytes play an essential role in neuronal maintenance and support, synaptic activity, neuronal metabolism, and amyloid-beta (Aβ) clearance. Alzheimer’s disease (AD) is a neurodegenerative disorder associated with cognitive and behavioral impairment. The transformation of astrocytes is involved in various neurodegenerative diseases, such as AD. Since astrocytes have functional diversity and morphological and physiological heterogeneity in the CNS, AD-related astrocytes might show various pathological phenotypes during AD. Astrocytes developing pathological phenotypes could contribute to AD progression. In this review, we provide an overview of the pathological phenotypes of astrocytes in the context of AD, highlighting recent findings in human and mouse AD.

Mitochondrial dysfunction has been implicated in the pathogenesis of insulin resistance and type 2 diabetes. Damaged mitochondria DNA (mtDNA) may have a role in regulating hyperglycemia during type 2 diabetes. Circulating cell-free mitochondria DNA (ccf-mtDNA) was found in serum and plasma from patients and has been linked to the prognosis factors in various human diseases. However, the role of ccf-mtDNA in chronic inflammation in type 2 diabetes is unclear. In this study, we hypothesized that the ccf-mtDNA levels are associated with chronic inflammation in patients with type 2 diabetes. The mtDNA levels were elevated in the plasma from patients with type 2 diabetes compared to healthy subjects. The elevated mtDNA levels were associated with interleukin-1β (IL-1β) levels in patients with type 2 diabetes. The mtDNA, from patients with type 2 diabetes, induced absent in melanoma 2 (AIM2) inflammasome-dependent caspase-1 activation and IL-1β and IL-18 secretion in macrophages. Our results suggest that the ccf-mtDNA might contribute to AIM2 inflammasome-mediated chronic inflammation in type 2 diabetes.

Renal fibrosis is a common pathogenic response to injury in chronic kidney disease (CKD). The receptor-interacting protein kinase-3 (RIPK3), a regulator of necroptosis, has been implicated in disease pathogenesis. In mice subjected to unilateral ureteral obstruction–induced (UUO-induced) or adenine diet–induced (AD-induced) renal fibrosis, models of progressive kidney fibrosis, we demonstrate increased kidney expression of RIPK3. Mice genetically deficient in RIPK3 displayed decreased kidney fibrosis and improved kidney function relative to WT mice when challenged with UUO or AD. In contrast, mice genetically deficient in mixed-lineage kinase domain-like protein (MLKL), a downstream RIPK3 target, were not protected from UUO-induced kidney fibrosis. We demonstrate a pathway by which RIPK3 promotes fibrogenesis through the AKT-dependent activation of ATP citrate lyase (ACL). Genetic or chemical inhibition of RIPK3 suppressed the phosphorylation of AKT and ACL in response to TGF-β1 in fibroblasts. Inhibition of AKT or ACL suppressed TGF-β1–dependent extracellular matrix production and myofibroblast differentiation in fibroblasts. Pharmacological inhibition of ACL suppressed UUO-induced kidney fibrosis. RIPK3 expression was highly regulated in human CKD kidney. In conclusion, we identify a pathway by which RIPK3 promotes kidney fibrosis independently of MLKL-dependent necroptosis as a promising therapeutic target in CKD.

To clarify the effect of anaesthetic agents on cancer immunity, we evaluated the effects of propofol and sevoflurane on natural killer (NK) cell, cytotoxic T lymphocyte (CTL) counts and apoptosis rate in breast cancer and immune cells co-cultures from patients who underwent breast cancer surgery. Venous blood samples were collected after inducing anaesthesia and at 1 and 24 h postoperatively in patients who had undergone breast cancer surgery. The patients were allocated randomly to the propofol- or sevoflurane-based anaesthesia groups. We counted and detected apoptosis in cancer cell, NK cell and CTL of patients with breast cancer by co-culture with a breast cancer cell line in both groups. We also evaluated changes in the cytokines tumour necrosis factor-alpha, interleukin (IL)-6 and IL-10 during the perioperative period. Forty-four patients were included in the final analysis. No difference in NK cell count, CTL count or apoptosis rate was detected between the groups. Furthermore, the number of breast cancer cells undergoing apoptosis in the breast cancer cell co-cultures was not different between the groups. No changes in cytokines were detected between the groups. Although basic science studies have suggested the potential benefits of propofol over a volatile agent during cancer surgery, propofol was not superior to sevoflurane, on the aspects of NK and CTL cells counts with apoptosis rate including breast cancer cell, during anaesthesia for breast cancer surgery in a clinical environment. NCT02758249 on February 26, 2016.